U.S. patent application number 12/001393 was filed with the patent office on 2008-06-05 for intravascular folded tubular endoprosthesis.
Invention is credited to William J. Drasler, Joseph M. Thielen.
Application Number | 20080132996 12/001393 |
Document ID | / |
Family ID | 23155132 |
Filed Date | 2008-06-05 |
United States Patent
Application |
20080132996 |
Kind Code |
A1 |
Drasler; William J. ; et
al. |
June 5, 2008 |
Intravascular folded tubular endoprosthesis
Abstract
A bifurcated or straight intravascular folded tubular member is
deliverable percutaneously or by small cutdown to the site of a
vascular lesion. Its inserted state has a smaller nondeployed
diameter and a shorter nondeployed length. The intravascular
tubular member has a folded tubular section that is unfolded
following insertion into the blood vessel. The length of the
intravascular folded tubular member is sized in situ to the length
of the vessel lesion without error associated with diagnostic
estimation of lesion length. The folded tubular member is
self-expandable or balloon-expandable to a larger deployed diameter
following delivery to the lesion site. An attachment anchor can be
positioned at the inlet or outlet ends of the intravascular folded
tubular member to prevent leakage between the tubular member and
the native vessel lumen and to prevent migration of the tubular
member. The attachment anchor has a short axial length to provide a
more focal line of attachment to the vessel wall. Such attachment
is valuable in attaching to a short aortic neck in the treatment of
abdominal aortic aneurysm. The attachment anchor can have barbs
which are held in a protected conformation during insertion of the
tubular member and are released upon deployment of the attachment
anchor. The intravascular tubular member can be formed of woven
multifilament polymeric strands with metallic strands interwoven
along with them. Double weaving is incorporated to prevent leakage
at crossover points.
Inventors: |
Drasler; William J.;
(Minnetonka, MN) ; Thielen; Joseph M.; (Buffalo,
MN) |
Correspondence
Address: |
WILLIAM J. DRASLER
4100 DYNASTY DRIVE
MINNETONKA
MN
55345
US
|
Family ID: |
23155132 |
Appl. No.: |
12/001393 |
Filed: |
December 11, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09299512 |
Apr 26, 1999 |
6287335 |
|
|
12001393 |
|
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Current U.S.
Class: |
623/1.15 |
Current CPC
Class: |
A61F 2/844 20130101;
A61F 2230/0054 20130101; A61F 2230/005 20130101; A61F 2/07
20130101; A61F 2002/075 20130101; A61F 2002/072 20130101; A61F
2002/8483 20130101; A61F 2/89 20130101; A61F 2002/065 20130101;
A61F 2250/0007 20130101 |
Class at
Publication: |
623/1.15 |
International
Class: |
A61F 2/82 20060101
A61F002/82 |
Claims
1-34. (canceled)
35. A wall structure for a cylindrical member that is deliverable
to the site of a lesion within a tubular vessel of the body, the
cylindrical member having a nondeployed state and capable of
undergoing an expansion deformation to a deployed state with a
larger diameter, said wall structure comprised of; A. one or more
hinges and one or more struts, B. said hinges being adapted to bend
substantially only in the direction of the hinge width, C. said
struts having a strut width that is greater than a strut radial
dimension wherein said strut is unable to bend substantially in the
direction of the strut width and is adapted to flex elastically and
not substantially plastically in the radial direction.
36. The wall structure of claim 35 wherein the said hinges provide
a plastic deformation of a material as said hinges deform during
the expansion deformation.
37. The wall structure of claim 36 wherein said struts formed of
said material are adapted to bend elastically in the radial
direction due to an external crush force and return to the original
shape upon removal of the crush force, thereby providing a
cylindrical member that is adapted to be balloon expandable but not
plastically crushable.
38. The wall structure of claim 35 wherein said hinges have an
expansion yield force in the direction of said hinge width and said
struts have an outward crush elastic force in the radial direction
that are uncoupled from each other thereby allowing these forces to
be adjusted independently from each other.
39. The wall structure of claim 35 wherein said hinges provide an
elastic expansion force in the direction of said hinge width that
is uncoupled from a crush elastic force provided by said struts in
a radial direction.
40. A cylindrical wall structure for use within a tubular vessel of
the body, deliverable to a site that requires a supporting
structure, said cylindrical wall structure having the ability to
exert an expansion force outward that is transmitted toward the
tubular vessel wall, said cylindrical wall structure further having
an independent ability to tolerate a temporarily applied external
crush force by becoming oval in shape and then returning back to
its approximate initial shape upon removal of the external force,
said tubular wall structure comprised of; A. hinges and struts that
are interconnected within said cylindrical wall structure, B. said
struts having a width enough greater than the width of said hinges
such that the struts do not contribute significantly to the
expansion force that is predominantly determined by said hinges, C.
said hinges having a radial dimension enough greater than the
radial dimension of said struts such that the hinges do not
contribute significantly to the elastic crush resistance force that
is predominantly determined by said struts.
41. The method of use for a cylindrical member that is deliverable
to the site of a lesion within a tubular vessel of the body, the
cylindrical member having a nondeployed state and capable of
undergoing an expansion deformation to a deployed state of larger
diameter, the method comprising; providing a wall structure with
hinges and struts, said hinges being adapted to be unable to bend
substantially in the radial direction; said struts being adapted to
be substantially unbendable in the direction of the strut width and
adapted to flex elastically and not significantly plastically in
the radial direction; whereby said cylindrical member is thereby
adapted to reversibly form an oval shape during a crush
deformation.
42. The method of use of claim 41 wherein at least some of said
hinges bend plastically in the direction of the hinge width during
the expansion deformation thereby adapting said cylindrical member
to be balloon expandable while said struts adapt said cylindrical
member to not be plastically crushable.
43. The method of claim 41 wherein the hinge width is made wider to
increase the force required to pivot the hinge.
44. The method of claim 41 wherein said hinge has a hinge length
that is decreased to cause a relatively elastic material to bend
plastically within a relatively small amount of rotation.
45. The method of claim 41 wherein said hinge has a hinge length
that is increased to cause a relatively plastic material to bend
elastically throughout a relatively large amount of rotation.
46. The method of claim 41 wherein the hinge radial dimension is
increased beyond that which is necessary to prevent the strut from
causing said hinge to flex in the radial direction, thereby
providing an increase the force required to pivot the hinge.
47. The method of claim 41 wherein the strut radial dimension is
made thicker to increase the force required to flex said strut in
the radial direction.
48. The method of claim 41 wherein the strut radial dimension is
decreased to reduce the force required to flex said strut in the
radial direction, and adapt said strut when formed from a
relatively plastic material to bend elastically throughout a
relatively large degree of flexing in the radial direction.
49. The method of claim 41 wherein said strut width is made wider
than that which is necessary to prevent bending in the direction
which said hinges pivot, thereby providing an increase in the force
required to flex said strut in the radial direction.
50. The method of claim 41 wherein said strut has a strut length
that is increased to cause said strut when formed from a relatively
plastic material to bend elastically throughout a relatively large
degree of flexing in the radial direction.
51. The method of claim 41 wherein the hinge width and hinge radial
dimension of any of said hinges, and the strut width and strut
radial dimension of any of said struts are adapted to have
different hinge width and hinge radial dimension than another of
said hinges and different strut width and strut radial dimension
than another of said struts.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of Invention
[0002] The present invention relates to a vascular implant that is
implanted into an artery for repair or bypass of arterial injury.
The vascular implant includes a stent-graft that is delivered
intraluminally into an artery for repair of a vascular lesion and
more specifically for repair of abdominal aortic aneurysm. The
vascular implant further includes an attachment means that provides
attachment of a stent-graft to a vessel wall.
[0003] 2. Description of Prior Art
[0004] An abdominal aortic aneurysm is an outpouching of the wall
of the aorta that can continue to expand over time possibly leading
to rupture and mortality. The outpouched wall is generally filled
with thrombus except for a generally tortuous pathway for blood
flow through an opening in the thrombus. This thrombus can become
organized over time as fibroblasts and other cell types infiltrate
and form a more organized matrix material containing collagen and
other tissue. Typically such aneurysms occur below or caudal to the
renal arteries or veins and can extend distally into the right or
left common iliac arteries or further distally into the right or
left femoral arteries. The right renal vein which crosses over the
ventral surface of the aorta can provide some support to the
ventral surface of the aorta an help resist aortic distention.
Aortic distention can occur very abruptly just distal to the renal
vessels reaching a diameter of six centimeters or greater and
causing the onset of accompanying symptoms and requiring repair.
Generally the blood flow pathway through the thrombus does not
follow these abrupt changes found in the vessel wall but rather
continues on in a more direct albeit tortuous path through the
thrombus found in the aneurysmal aorta. The abdominal aortic
aneurysm can sometimes have a proximal neck or region where the
aortic diameter appears to be of normal diameter. This proximal
neck region is sometimes found just caudal to the renal vessels.
The abdominal aortic aneurysm can sometimes also have a distal neck
region located just proximal to the aorto-iliac bifurcation. In
this minority of patients the abdominal aortic aneurysm does not
extend to the iliac arteries or further distally. Aortic distention
in the majority of patients can extend into one or both of the
iliac or femoral arteries; repair of this abdominal aortic aneurysm
can involve treatment of the iliac and femoral arteries as well.
The common iliac artery divides to form the external and internal
iliac arteries. The internal iliac artery (also called the
hypogastric artery) is important in providing a supply or blood to
the pelvic region, genital organs, and other areas and is most
often not aneurysmal. The external iliac artery is commonly
involved in the aneurysm and extends distally along an oftentimes
very tortuous path to form the common femoral artery.
[0005] Surgical repair of an abdominal aortic aneurysm is an
extensive procedure associated with a high incidence of morbidity
and mortality and requiring many days of hospital stay. Older
patients are often not capable of withstanding the trauma
associated with this surgery. Repair of abdominal aortic aneurysm
intraluminally through access from the common femoral artery can
provide the patient with an alternate method of treatment for
abdominal aortic aneurysm without the accompanying surgical trauma
and long hospital stay. Placement of an intraluminal stent-graft
can be performed by an interventionalist using a minimal surgical
cutdown to an ipsilateral common femoral artery for access of the
device to the arterial system of the body. Generally an additional
access site is placed percutaneously in the contralateral common
femoral artery. It is often preferred to place at least one more
access site cranial to the abdominal aortic aneurysm generally
through an axillary artery or other artery of the arm. Spiral
computed tomography, duel-plane angiography, intravascular
ultrasound, magnetic resonance imaging, and fluoroscopy provide
some of the diagnostic techniques used to determine the position,
diameter, and length of the aneurysm such that an appropriate
intraluminal prosthesis can be selected for intraluminal
implantation. Placement of the intraluminal stent-graft requires
that a leak tight seal be made between the stent-graft and the
aorta and between the stent-graft and each of the iliac or femoral
arteries if they are involved in the aneurysm. Failure to provide
such a leak tight seal will allow blood flow at arterial pressure
to access the space between the stent-graft and the outpouched
aorta. Continued exposure to arterial blood pressure can result in
further expansion of the aneurysmal sac and could lead to sac
rupture. Several intraluminal stent-grafts have been described for
use in treatment of abdominal aortic aneurysms.
[0006] Barone describes in U.S. Pat. No. 5,578,072 an apparatus for
repairing an abdominal aortic aneurysm. He describes a one-piece
bifurcated aortic graft having a balloon expandable stent at one
end to secure main trunk of the stent-graft to the aorta caudal to
the renal arteries. The one-piece aortic graft has additional
expandable stents positioned at the end of each leg of the
bifurcated graft to secure the stent-graft to the iliac arteries.
This design requires that the length of the main trunk and length
of each limb be established prior to implantation using the
diagnostic techniques described earlier. Due to the tortuous nature
of the blood flow pathway, it is impossible to properly size the
length of the graft using these diagnostic techniques prior to
implatation. If the stent-graft is sized too short, then a portion
of the aneurysm may be left unprotected. If the stent-graft is
sized too long for example, then the blood flow to one or both of
the internal iliac arteries may be compromised. The method of
securing the main trunk of the stent-graft to the aorta caudal to
the renal arteries described by Barone is also inadequate in many
situations. A balloon expandable stent placed caudal to the renal
vessels will very often be located within thrombus and will not
have the strength or stability of the aortic vessel wall to support
the stent or the stent-graft from migration caudally. Barone
teaches that a securing means that is expanded outwardly over an
axial length will hold the cranial end of the main trunk in
position near the renal vessels. Barone also does not describe any
means to prevent the stent-graft from being kinked or crushed as it
travels through the thrombus laden blood flow pathway within the
aortic aneurysm. Forces imposed upon the stent-graft due to the
surrounding thrombus or thrombus organization could easily cause
the stent-graft of Barone to become kinked or stenotic thereby
impairing its performance. Barone discusses the need to place a
stent proximal to the renal arteries for the case that the
abdominal aortic aneurysm extends through the aortic region
containing the renal arteries. He does not provide a suitable
stent-graft for treating infrarenal aortic aneurysm with abrupt
wall distension just distal to the renal vessels.
[0007] Parodi describes in U.S. Pat. No. 5,591,229 stent-graft
devices that are similar to those described by Barone in the above
patent. Additionally, Parodi describes a stent-graft for treatment
of an abdominal aortic aneurysm that does not extend into the iliac
region. This straight tubular stent-graft has a balloon expandable
stent positioned at its cranial end for placement into the proximal
neck of the aorta distal to the renal vessels. A balloon expandable
malleable wire is placed at the distal end of the stent-graft to
provide contact of the stent-graft with the aortic wall in the
distal neck of the aorta. This stent-graft has a similar problem
associated with estimating the graft length due to the tortuosity
associated with the blood flow pathway through the thrombus laden
aortic aneurysm. The other problem sited with the device described
by Barone are similarly shared by the Parodi device.
[0008] Chuter describes in U.S. Pat. No. 5,693,084 a one-piece
bifurcated stent-graft for treatment of abdominal aortic aneurysm
having self expanding springs positioned at the proximal end of the
main body and at the distal ends of each limb of the graft. The
springs expand radially upon release to conform the ends of the
stent-graft to the lumen of the aorta. This stent-graft suffers the
same problem described for Barone in determining the length of the
stent-graft prior to implant. Further, the stent-graft material is
not supported throughout the entire stent-graft length thereby
providing ample opportunity for stent-graft kinking and deformation
within the aneurysm. Chuter has positioned six barbs that extend
outward from the self expanding spring on the proximal end of the
stent-graft. Due to the geometry of the springs, the positioning of
the barbs into aortic wall rather than into the thrombus contained
within the aneurysmal wall is not very precise. This can lead to
stent-graft migration after a period of time post implant. Other
problems associated with the Barone device similarly apply to the
Chuter device.
[0009] McDonald describes in U.S. Pat. No. 5,676,697 a two-piece
component bifurcated intraluminal stent-graft for treatment of
abdominal aortic aneurysm. The first stent-graft component is a
flexible tubular member with a side cut near the middle of the
tubular member that opens up via a self expanding stent to form a
waist region that is seated in the aorto-iliac bifurcation region.
Two legs of the first stent-graft component are seated into each
iliac artery using stents attached to the distal end of each leg. A
second stent-graft component is introduced through one leg of the
first component and allowed to self expand in the main trunk of the
aorta and form a seal with the waist of the first component. The
proximal end of the second component extends proximally within the
aorta and makes a seal as it expands outwardly against the flow
lumen. This device would have difficulty with positioning the
proximal end of the second component within the proximal neck of
the aorta. Extreme tortuosity found in the flow lumen of the aortic
aneurysm would not allow this device to conform to its shape and
would not allow a tight seal to be formed between the proximal end
of the second component and the aorta. Difficulty in determining
the appropriate length for each of the two components would limit
the usefulness of this device.
[0010] Glastra describes in U.S. Pat. No. 5,632,763 a bifurcated
component stent-graft assembly for treatment of abdominal aortic
aneurysm. The assembly consists of a base stent-graft that is
introduced into the main trunk of the aorta from an intraluminal
approach. The base stent-graft has a generally cylindrical shape
with a conical region located at the distal end. Two secondary
cylindrical stents are introduced through two branching arteries,
one in each leg and are seated in the conical region of the base
stent-graft. This assembly has several potential problems
associated with it. Determining the appropriate length of the base
stent-graft and each of the secondary stent-grafts cannot be
accurately performed considering that all of the arteries involved
can be very tortuous and difficult to estimate in length. The seal
that is required at the junction of the main to the secondary
stent-grafts may have a tendency for leakage due to the geometry of
that junction. Glastra describes two cylindrically shaped secondary
stent-grafts that are placed adjacent to each other and are
required to expand out and seal against a larger cylindrical base
stent-graft; this seal would be difficult to form and maintain.
Glastra does not address specific means for attachment of the
proximal end of the base stent-graft to the aorta.
[0011] Marcade describes in U.S. Pat. No. 5,683,449 a modular
system for forming a bifurcated stent-graft for use in treating
abdominal aortic aneurysm. The system includes a number of
components that are delivered intraluminally to the site of the
aneurysm and brought into contact with each other within the
aneurysmal space. The primary graft member has a proximal stent at
one end and has an decreasing diameter as the stent-graft extends
towards its distal end. The base member has a Y-shaped structure
with a proximal end that contacts the distal end of the primary
graft member. The base member also forms two branches on its distal
end, each branch being brought into contact with a tubular graft
member that extends into an iliac artery. This modular system still
requires that each individual component be sized for length and
diameter in order to fit the vast differences found between
abdominal aortic aneurysm patients. Each junction between
individual components is also a site for potential leakage of blood
into the space between the stent-graft and the native arterial
conduit. Marcade shows approximately five barbs positioned on the
proximal stent. Due to the geometry of the stent it is not possible
to obtain precise positioning of the barbs into the aortic wall
tissue to ensure long term anchoring that would prevent stent-graft
migration and maintain an adequate leak tight seal.
[0012] Vorwerk describes in U.S. Pat. No. 5,562,724 describes a
component bifurcated device for treating abdominal aortic aneurysm
consisting of a main body and two tubular stent-grafts. The main
body has an open proximal end and a distal bag-shaped end with two
outlet openings formed in it. Two tubular stent-graft legs can be
introduced through the iliac arteries of the patient and attached
to the two outlet openings of the main body. Sizing the appropriate
length of the main body in addition to the two stent-graft legs is
difficult due to the tortuosity found in the blood flow pathway of
the aorta and iliac arteries. Leakage at the attachment site of the
stent-graft legs to the main body also is a major concern.
[0013] Palmaz describes in U.S. Pat. No. 5,683,453 and Marin in
U.S. Pat. No. 5,507,769 two tubular stent-grafts that travel in
parallel from the infrarenal aortic neck to each iliac artery. Each
stent-graft has a stent positioned at each end of the tube to form
a seal with the native artery. This system would also have
difficulty in determining the appropriate length of the stent-graft
due to vessel tortuosity. In addition, this system requires that
the two proximal stents deform against each other and with the
proximal neck of the aorta to form a leak tight seal; it is not
likely that an appropriate seal or attachment to the proximal
aortic neck would be made. Extending a plurality of stent tubular
members further within the length of stent-graft create a
stent-graft that is too stiff to pass through a tortuous iliac
artery to reach the site of the abdominal aortic aneurysm.
[0014] Egoda describes in U.S. Pat. No. 5,591,228 a method of
introducing a bifurcated stent-graft for abdominal aortic aneurysm
treatment using three access points into the arterial vasculature.
As with other intraluminal stent-graft procedures, two access sites
involve the common femoral arteries. Egoda describes a third access
site made in the left subclavian artery through which the
stent-graft can be introduced. This method may allow better control
over both ends of the stent-graft during implantation. The length
of the stent-graft must still be determined prior to implant and
estimation of the length of the blood flow pathway is difficult to
determine using standard diagnostic equipment due to the tortuosity
of the vessels involved in the aneurysmal dilation.
[0015] A one-piece endovascular graft is described by Piplani in
U.S. Pat. No. 5,824,039 for treating a bifurcated abdominal aortic
aneurysm lesion. This device has springs located at inlet and
outlet ends to hold the graft in place. The springs also have barbs
attached. The springs have a large zig zag appearance similar to
other prior art attachment means and the barbs are not well
protected from inappropriate snagging prior to deployment of the
endovascular graft.
[0016] Modular intraluminal prosthesis are described by Lauterjung
in U.S. Pat. No. 5,824,036 and by Fogarty in U.S. Pat. No.
5,824,037. Lauterjung describes a composite system using a magnetic
tipped guidewire to assist in the assembly of the prosthesis and
employs a stent at the ends of the prosthesis and elsewhere.
Fogarty describes a self-expanding or resilient frame with a
plastically deformable liner over the frame limiting the resilient
expansion. Each of these two composite or modular systems shares
similar problems to the composite systems described earlier,
including the potential for leakage at the junction sites as well
as leakage at the junction of the prosthesis with the vessel
lumen.
SUMMARY OF THE INVENTION
[0017] The present vascular implant overcomes the disadvantages of
prior art stent-grafts, attachment means, and vascular tubular
members used for endoprosthetic aortic or arterial aneruysmal
repair, or for arterial bypass or other arterial or venous
reconstruction. The vascular tubular member of the present
invention includes a vascular tubular member that can be
intravascularly delivered to the site of vessel injury such as an
aortic aneurysm where it is deployed in a manner that will exclude
the vessel injury or aneurysm. This intravascular tubular member
conveys blood flow from a proximal arterial region that is located
proximal to an arterial lesion or aneurysm to one or more distal
arterial vessels. One embodiment of the present invention is an
intravascular tubular member having a folded tubular section that
allows the length of the graft to be adjusted during the time of
deployment of the intravascular tubular member. This intravascular
tubular member allows the physician to deploy the exact correct
length of tubular member for each individual patient and allows the
intravascular tubular member to fit different patients that require
intravascular tubular members of different lengths. The
intravascular tubular member further can have a proximal attachment
anchor positioned at its proximal end that allows the proximal end
to be positioned accurately in the aortic wall tissue adjacent and
distal to the renal arteries. The attachment anchor of the present
invention is an attachment anchor that does not undergo significant
length change during deployment thereby allowing the position of
the attachment anchor within the aortic aneurysm to be accurately
determined. The intravascular tubular member can also be anchored
to the aorta proximal to the renal vessels for the condition that
the aortic aneurysm is abruptly distended adjacent and distal to
the renal arteries. The attachment anchor can include barbs to more
firmly anchor the intravascular tubular member to the vessel wall.
The intravascular tubular member can also include a distal
attachment anchor to anchor the distal end of the intravascular
tubular member to one or more distal vessels.
[0018] The structure of the vascular tubular member includes a
woven structure formed from either multifilament polymeric strands
or a composite of multifilament polymeric strands woven along with
metal strands. This structure of the vascular tubular member wall
is such that it can be supported in both the axial and
circumferential directions with metal strands. The
circumferentially oriented metal strands provide anti-kink and
anti-crush characteristics to the vascular tubular member. The
axially oriented metal strands can provide the vascular tubular
member with axial compression resistance and ensure that the folded
tubular section is maintained in a straight tubular form. These
characteristics will provide the tubular sections of the present
invention with a more stable pathway for the intravascular tubular
member through the thrombus found within a typical abdominal aortic
aneurysm. The one-piece construction of the intravascular tubular
member of this invention does not allow for leakage at modular
junctions such as that which can occur with prior art component or
modular intravascular tubular member systems described earlier. One
primary application for the intravascular tubular member of the
present invention is in the treatment of abdominal aortic
aneurysms. Although the description of the invention in this
disclosure is directed toward treatment of abdominal aortic
aneurysm, it is understood that the present invention is intended
for treatment of other vascular lesions both arterial and venous
including vessel bypass, traumatic injury, aneurysmal repair, and
other lesions.
[0019] The intravascular tubular member of the present invention
can be formed from a single straight tube having a proximal end and
a distal end. As the intravascular tubular member is being inserted
into the patient, it has a smaller nondeployed diameter and a
shorter nondeployed length. After the intravascular tubular member
is fully deployed, it has a larger deployed diameter and a longer
deployed axial length. The straight intravascular folded tubular
member is comprised of three sections, a proximal tubular section
that includes a proximal tube with an open inlet end, a folded
tubular section which includes a folded tube that is able to extend
in axial length, and a distal tubular section that includes a
distal tube with an open distal end. The proximal, folded, and
distal sections are of a length that allows ease of insertion and
implantation of the intravascular folded tubular member to vascular
application. Alternately, the distal section can be very short and
may only include the outlet end of the folded section. In the
folded tubular section the folded tube is folded back and forth
upon itself generating two circumferential fold lines and forming
the folded tubular section of the intravascular folded tubular
member. In the folded tubular section a portion of the outer
surface of the intravascular folded tubular member is in direct
contact with another portion of the outer surface, and a portion of
the inner surface is in direct contact with another portion of the
inner surface of the intravascular folded tubular member. The
nondeployed axial length of the intravascular folded tubular member
is shorter than the deployed axial length; the folded tubular
section length will shorten as the deployed axial length of the
intravascular folded tubular member gets longer. The folded tubular
section is positioned distal to the proximal tubular section which
can have a proximal attachment anchor attached at the proximal end.
Distal to the folded tubular section is a distal tubular section
that can have a distal attachment anchor attached at or near the
distal end.
[0020] The intravascular folded tubular member can be delivered
intraluminally by compressing the intravascular folded tubular
member radially to form a compressed conformation that can be
delivered to the abdominal aorta or other vessel through a sheath
or other delivery means placed in a common femoral artery. Upon
delivery of the intravascular folded tubular member into the aorta,
the intravascular folded tubular member expands to its deployed
diameter. For a self-expanding intravascular folded tubular member
the deployed diameter is between the nondeployed diameter and an
equilibrium diameter that the intravascular folded tubular member
would attain if fully deployed without a restricting force applied
from the vessel with which it is in contact. The deployed diameter
is generally approximately equal to the diameter of the native
vessel that is being repaired. The intravascular folded tubular
member can also be expanded by a catheter containing a mechanical
expansion means such as a balloon. A proximal attachment anchor can
be deployed to form an attachment that seals the proximal end of
the intravascular folded tubular member to the aortic wall adjacent
and distal to the renal vessels. The proximal attachment anchor
does not undergo a significant axial length change during its
deployment and as a result can be placed accurately in a position
adjacent to the renal vessels for a more reliable attachment to the
aortic wall. This reduces any chance for distal migration of the
intravascular folded tubular member over time. Attachment of the
intravascular folded tubular member to the attachment anchor of the
present invention occurs at significantly more sites than is found
with other prior art abdominal aortic aneurysm intravascular folded
tubular members with zig-zag wire attachment means. The increased
number of attachment sites provides a better seal of the attachment
anchor and the intravascular folded tubular member to the aortic
wall. Barbs can be located on the attachment anchor of the present
invention such that they are folded inward during insertion of the
device and extend outwards upon deployment of the intravascular
folded tubular member.
[0021] The distal end of the intravascular folded tubular member is
then positioned at an appropriate location within the abdominal
aorta, typically at the site of the distal aortic neck if such a
neck exists. It is common to position the distal end of the
intravascular folded tubular member into an iliac or femoral
artery. As the distal end of the intravascular folded tubular
member is being positioned, a portion of the folded tubular section
will be unfolded allowing intravascular folded tubular member
material contained within the folded tubular section to unfold
thereby allowing the intravascular folded tubular member to
lengthen to an appropriate deployed axial length that is required
to isolate an aneurysm, bypass an artery, or repair in some other
way an artery for that individual patient. The length of the
tortuous blood flow pathway through the thrombus in the aortic
aneurysm can be accurately and appropriately sized in situ when
using the intravascular folded tubular member of this
invention.
[0022] The material of construction for the wall of the vascular
tubular member with a folded tubular section as described
previously can be any material that is used in vascular grafts or a
combination of materials used in vascular grafts and endovascular
stents. Typical vascular graft materials include expanded
polytetrafluoroethylene, polyester, silicone, carbon,
polyurethanes, biological tissues, silk, composite materials, and
others. Some of these materials can be formed into a tube through
processing methods that include paste extrusion, electrostatic
spinning, spinning without electrostatics, salt leaching, and
others. Additionally, the vascular tubular member of this invention
which includes the intravascular folded tubular member can be
formed from fibers of the materials listed above that have been
woven, braided, knitted, or formed into a tubular member. The
fibers can preferably be formed of many filaments of a very small
diameter and which are wound to form a multifilament fiber or
strand Such a multifilament fiber can offer an enhanced sealing
capability at the crossover points of a woven or braided fabric
vascular tubular member material. It is therefore preferred that a
woven or braided tubular member be formed with multifilament yarn
or multifilament fibers to reduce blood leakage at crossover points
of polymer strand with polymer strand or polymer strand with
metallic strand. Typical materials used in the construction of
endovascular grafts and stents include Nitinol, stainless steel,
tantalum, titanium, platinum, and other metals, metal alloys, and
other suitable materials of large elastic modulus. Strands of these
and other materials can be interwoven or interbraided with the
polymeric materials used in vascular grafts to form a composite
wall structure of the present invention.
[0023] A tubular double weaving method can be applied to the
construction of the wall of the present vascular tubular member. A
construction that involves weaving both polymeric fiber and
metallic strands in both longitudinal and circumferential
directions can encounter crossover points of one metal strand with
another. At such crossover points, leakage or seepage of blood can
occur from inside the vascular tubular member to the space outside
the vascular tubular member. To reduce or eliminate small pores at
the crossover points a tubular double weave is preferred when a
metal strand is woven on both the axial and circumferential
directions. With this technique a metal strand in one direction is
brought out of the surface or the plane of the weave at the
crossover point. The woven polymeric material without the metal
strand forms a continuous plane of weave beneath the crossover
point with good sealing due to the multifilament strands. Thus,
leakage cannot occur at metallic strand to metallic strand
crossover points due to the elimination of the pores or leakage
sites due to the double weaving.
[0024] The attachment anchor that can be positioned at the proximal
and distal ends of the intravascular tubular member can be of the
self-expanding design or it can require an internal force
application to force it outward, such as that provided by a balloon
expandable means. The attachment anchor can be used with an
intravascular tubular member that has a folded tubular section or
it can be used with any other tubular member found in the prior art
or that is being used for intravascular treatment of vessel injury.
The metal strands that can be interwoven or interbraided into the
wall structure of the intravascular tubular member can preferably
be of a spring nature such that they self expand from the
compressed state to form the deployed diameter; the metal wires can
also undergo a plastic deformation as the intravascular tubular
member undergoes expansion from its compressed conformation to its
deployed diameter upon exposure to forces imposed by a balloon
catheter placed within its lumen.
[0025] One preferred embodiment the intravascular folded tubular
member of the present invention is a one-piece bifurcated tubular
structure or means that is used in the treatment of abdominal
aortic aneurysm. The intravascular folded tubular member has a
proximal tubular section with a single open inlet end and a
bifurcated main trunk that provides passage into two proximal leg
tubes. Each proximal leg tube is joined to a folded tubular
section, and each folded tubular section is joined to a distal
section. The proximal tubular section has a deployed diameter
approximately equal to the diameter of the aorta at the aortic
proximal neck immediately adjacent and distal to the renal vessels.
The two proximal leg tubes can have a diameter approximately equal
to the diameter of the iliac artery or femoral artery into which
they are to extend. The proximal end of the main trunk can have an
attachment anchor attached to provide accurate attachment of the
open proximal end within the proximal neck of the aorta. The
attachment anchor can include barbs or hooks that provide a more
definite attachment of the intravascular folded tubular member to
the wall of the aorta to prevent migration, provide a leak-tight
seal, and help support the aorta from further distension at that
location. The folded tubular sections each have two circumferential
fold lines and are folded back and forth in a manner similar to
that described earlier for the straight intravascular folded
tubular member. Each folded tubular section has a portion of the
outer surface of the intravascular folded tubular member in direct
contact with a another portion of the outer surface, and it has a
portion of the inner surface of the intravascular folded tubular
member in direct contact with another portion of the inner surface.
The folded tubular sections allow the bifurcated folded tubular
member to assume a shorter nondeployed axial length during the
delivery of the intravascular folded tubular member than its
deployed axial length. Each folded tubular section is attached to a
distal tubular section with an open distal end. The open distal end
of each distal tubular section can have an attachment anchor
attached to form a precise and leak-free attachment to the iliac or
femoral arteries.
[0026] A preferred bifurcated intravascular tubular structure or
member of the present invention consists of a proximal tubular
section or means with a proximal attachment anchor attached to its
inlet end, two folded tubular sections attached to the proximal
tubular section, two distal tubular sections attached to the two
folded tubular sections, and two distal attachment anchor attached
to each open distal end. The bifurcated intravascular tubular means
is generally introduced into the aneurysmal abdominal aorta
intraluminally through a surgical cut down or percutaneous access
made into one common femoral artery. A sheath or other introducing
means provides suitable access for the intravascular folded tubular
member into the blood flow pathway of the aorta. Attachment of the
proximal attachment anchor to the aorta is generally made adjacent
and distal to the renal vessels. This attachment anchor can be a
self-expanding attachment anchor or a balloon expandable attachment
anchor. The attachment anchor is preferably short in axial length,
has minimal length change upon deployment to allow more accurate
placement, and can have barbs extending outward upon deployment to
provide better attachment of the intravascular folded tubular
member to the vessel wall. The two distal sections of the
bifurcated tubular means are generally positioned in the right and
left iliac arteries, respectively. The distal ends of the two
distal section along with the two distal attachment anchor are
positioned at an appropriate location within the iliac or femoral
arteries so as to properly exclude the abdominal aortic aneurysm
and any additional iliac or femoral aneurysm. As these distal ends
are being positioned, the two folded tubular sections will unfold
an appropriate amount to allow the deployed axial length of the
bifurcated tubular means to be precisely sized to the individual
patient. Variations between patients can be accommodated with the
folded tubular sections as well as inaccuracies between
angiographic length estimations of the aortic aneurysm and the
actual length of the aneurysm.
[0027] Distal attachment anchor which are attached to the distal
ends of the distal tubular sections can be deployed to form a
secure and leak-tight attachment to each iliac artery or femoral
artery. The wall structure of the bifurcated folded tubular member
is similar to that described for the single straight tube. A woven
or braided composite of a polymeric multifilament fiber interwoven
or interbraided with a metal fiber can be formed into a one-piece
Y-shaped tubular means of the present invention for treatment of
abdominal aortic aneurysm with a bifurcated intravascular folded
tubular member. Tubular double weaving can be used to reduce
leakage sites at crossover points of the metal fibers or
strands.
[0028] Another embodiment for the abdominal aortic aneurysm
intravascular folded tubular member of the present invention has a
proximal section with a bifurcated main trunk having an open inlet
end and joined to two proximal leg tubes. In this embodiment only
one proximal leg tube is joined to a folded section. The other
proximal leg tube has an open distal end that is adapted to
accommodate a cylindrically shaped intravascular folded tubular
member that can be inserted into the open distal end and sealingly
engaged with the proximal leg tube using an engagement means
positioned on the cylindrically shaped intravascular folded tubular
member. This sealing engagement on one side of the proximal section
is similar to the modular systems shown for treatment of abdominal
aortic aneurysm in the prior art. This embodiment allows one part
of the bifurcated intravascular folded tubular member to be
unfolded and extended in length in a manner similar to previous
embodiments described in this invention, and the other part of the
bifurcated intravascular folded tubular member to be extended by
adding additional intravascular folded tubular member segments in a
modular fashion as described in the prior art.
[0029] The folded tubular section for the straight or bifurcated
intravascular folded tubular member of the present invention has
three layers of intravascular folded tubular member wall that lie
in direct contact with or in apposition with each other, an outer
wall, a center wall, and an inner wall. These three layers extend
from a proximal end to a distal end of the folded tubular section.
The length of the folded tubular section becomes shorter as the
intravascular folded tubular member becomes extended axially during
the deployment of the intravascular folded tubular member. In the
folded tubular section a portion of the outer surface of the
tubular means is in direct contact with the outer surface of
another portion of the tubular means, and a portion of the inner
surface is in direct contact with another portion of the inner
surface. As the folded tubular section becomes unfolded during the
deployment it is desirable for the center wall to not wrinkle
during the unfolding process. Such wrinkling can occur if the inner
and outer wall slide with respect to the center wall rather than
unfolding smoothly from the proximal or distal ends of the folded
section. One way of significantly reducing or preventing this
wrinkling from occurring is to apply a bonding agent or adhesive to
the outside surfaces of the folded tubular section. This adhesive
is preferably one that resists the shearing motion that is
associated with the relative sliding motion that can cause wrinkles
to form. The adhesive should also be capable of undergoing fracture
due to exposure to extensional or tension stresses that are
generated during the desirable unfolding from the proximal or
distal ends of the folded section.
[0030] Following deployment of the intravascular folded tubular
member of the present invention, it may be desirable to ensure that
further unfolding of the folded region does not occur. one or more
securing pins or other securing means can be placed through all
three walls of the folded tubular section to prevent any further
unfolding that may occur after implantation.
[0031] The vascular implant of the present invention includes an
attachment anchor that can be attached to the inlet or outlet ends
of the intravascular tubular member of this invention, the
intravascular folded tubular member of this invention, or of any
other prior art tubular means used for intravascular implant. The
attachment anchor is formed from a metal tube using machining
methods that include mechanical, laser, chemical, electrochemical,
or other machining methods to form a pattern of nodes and struts.
The nodes and struts are intended to provide independent adjustment
of expansion force provided by the attachment anchor uniformly
outward against the vessel wall due to its expansion deformation
and crush elastic force provided by the attachment anchor against
external forces that tend to cause the attachment anchor to form an
oval shape associated with crush deformation. The independent
adjustment of expansion forces due to deformation in the
cylindrical surface of the attachment anchor from the crush force
which produces a deformation to a smaller radius of curvature in
the radial direction of the attachment anchor such as forming an
oval shape, allows the attachment anchor of the present invention
to have a shorter axial length for a better focal line attachment
to the vessel wall.
[0032] The nodes are formed of at least one hinge and two
transition regions. The transition regions are each attached to a
strut. A series of struts and nodes are positioned such that the
struts are aligned adjacent to each other forming a single folded
ring of struts and nodes with a generally cylindrical shape in a
nondeployed state with a smaller nondeployed diameter. The
attachment anchor of the present invention can be a
balloon-expandable or a self-expanding attachment anchor. During
expansion of the balloon-expandable attachment anchor, an expanding
means such as a balloon dilitation catheter can be inserted along a
central axis of the attachment anchor and expanded. The hinges
undergo a plastic expansion deformation as the attachment anchor is
expanded to a deployed state with a larger deployed diameter. In a
deployed state the hinge exerts an outward expansion force through
the struts which in turn push against the blood vessel to hold the
vessel outwards and hold the intravascular tubular member against
the vessel wall without leakage. A self-expandable attachment
anchor is held, for example, within a deployment sheath at a
smaller nondeployed diameter for delivery into the vasculature. The
hinge is deformed elastically in its nondeployed state and exerts
an outward force against the sheath. Upon release from the sheath
the self-expandable attachment anchor expands outward until it
comes into contact with the vessel wall or the intravascular
tubular member. The hinge exerts an outward elastic expansion force
through the struts which in turn push against the blood vessel to
hold the vessel outwards and hold the intravascular tubular member
against the vessel wall without leakage.
[0033] Hinges of the present invention have a larger radial
dimension than the struts and a thinner width than the struts; the
hinge length further having a major role in establishing the
outward expansion forces generated by the hinges. The hinge length
can be short to focus the expansion deformation of the hinge into a
smaller area. For a balloon-expandable attachment anchor the
smaller hinge length increases the percentage of metal in the hinge
that undergoes a plastic deformation. The result is less rebound of
the attachment anchor back towards its nondeployed state following
balloon expansion. For a self-expandable attachment anchor the
smaller hinge length will generate a greater expansion force for a
smaller localized expansion deformation of the hinge. A longer
hinge for a self-expandable attachment anchor provides a smaller
drop-off of outward expansion force than a smaller hinge length for
a specific deployment angle of the attachment anchor. The larger
hinge length allows a similar outward force to be applied to the
blood vessel wall for a wider range of vessel diameters for the
same attachment anchor. For a balloon-expandable attachment anchor
an increase in hinge width causes a greater amount of plastic
deformation and provides a larger expansion force generated by the
hinge than a smaller hinge width. For a self-expandable attachment
anchor an increase in hinge width causes a larger outward expansion
elastic force to be exerted against the vessel wall. A hinge radial
dimension larger than the strut radial dimension produces a larger
outward expansion force for both the balloon-expandable or
self-expandable attachment anchor. The large hinge radial dimension
does not allow the hinge to bend in a radial direction to form an
oval such as would like to occur during exposure to a crush
deformation.
[0034] The struts of the attachment anchor have a larger width than
the hinge width such that the hinges can transfer their outward
force through the struts to the vessel wall without allowing any
bending of the struts in the cylindrical surface of the attachment
anchor. The struts have a small radial dimension in comparison to
the hinge radial dimension to allow the struts to deform
elastically to a smaller radius of curvature in the radial
direction of the attachment anchor upon exposure to a crush
deformation. The strut width allows the struts to deform
elastically at any prescribed crush force during exposure to a
crush deformation. A longer strut length allows a greater
percentage of the perimeter of the attachment anchor to be
associated with the struts in comparison to the hinges or nodes.
The longer struts provide the attachment anchor with an increased
flexibility in the radial direction when exposed to a crush
deformation. Conversely, a shorter strut provides the attachment
anchor with a greater stiffness in the crush deformation mode with
other attachment anchor dimensions remaining the same. The greater
stiffness associated with an attachment anchor with such a shorter
length strut allows the strut to be formed with a thinner radial
dimension or smaller width and still have the same flexibility in
crush deformation as a longer strut.
[0035] The attachment anchor of the present invention can be formed
out of a higher modulus metal that other attachment devices. Other
prior art attachment devices cannot be formed of the highest
modulus metal because their expansion force cannot be changed
without also affecting their crush force. With the present
attachment anchor the outward expansion force can be designed
independently from the crush force provided by the attachment
anchor. The present attachment anchor can be formed such that it is
short in axial length in order to provide a more focused line of
attachment to the vessel wall. Short stents formed with prior art
designs can be designed to provide an appropriate outward expansion
force, however this prior art stent would be too stiff or too
flexible in a crush deformation and would be without the ability to
adjust the crush deformation force with respect to the outward
expansion force. The present attachment anchor can be designed to
provide both an appropriate expansion force and an appropriate
crush force. The hinge of the present attachment anchor can also
provide more expansion force than other prior art attachment
devices due to the use of higher modulus metal and due to the
dimensions chosen for the hinge width, length, and radial
dimension. The close efficient packing of the struts parallel to
each other provides the present attachment anchor with a large
expansion ratio. The short strut length allows the strut width to
be minimized while still maintaining an appropriate flexibility in
crush deformation further maximizing the expansion ratio provided
by the present attachment anchor. The strong expansion force
provided by the hinge allows an appropriate expansion force to be
generated such that the attachment anchor of this invention with
short axial length can provide adequate expansion forces to hold a
large vessel such as the aorta outward and prevent leakage between
the intravascular tubular member and the vessel wall.
[0036] The vascular tubular member tubular wall structure can be
formed from a composite of polymeric and metallic strands that are
either woven or braided to provide different characteristics in its
axial and circumferential directions. In a weaving process for
tubular structures one or more strands have substantially a
circumferential direction and another group of strands have
generally an axial direction. In a weaving process the
substantially circumferential strands generally have a gradual
helical wind that is approximately perpendicular to the
longitudinal axis of the vascular tubular member but the strands
are continuous and actually form a helix. A polymeric strand can be
made up of substantially straight filaments to form a straight
polymeric strand. This straight polymeric strand can be woven in a
circumferential direction forming a straight circumferential
polymeric strand, or woven in an axial direction forming a straight
axial polymeric strand. The polymeric strand can also undergo a
thermal, mechanical, or chemical forming process that can heat set,
mechanically set, or chemically deform the polymer filaments or the
strand to have local bends, helical spirals, or curves in it. The
local bends can be spaced very close together with spacing
approximately equal to the diameter of the filament. Alternately,
the local bends can be spaced apart further than the diameter of a
fiber that is made up of many filaments. This curved polymeric
strand will have the characteristic that it can stretch or elongate
in its axial direction. This curved polymeric strand can be woven
in a circumferential direction forming a curved circumferential
polymeric strand, or it can be woven in an axial direction forming
a curved axial polymeric strand. The straight or curved polymeric
strand could be made from filaments of expanded
polytetrafluoroethylene, from filaments of Dacron polyester,
polyurethane, or from other suitable polymeric filaments.
[0037] The metallic strands that could be interwoven between the
polymeric strands could be formed from a straight metallic strands,
fibers, or wire formed from a metal such as Nitinol, stainless
steel, titanium, tantalum, or other suitable metal or alloy. The
wire can be round in cross section or it can be flat wire with a
more rectangular cross section. It is preferable for one embodiment
that the wire or metallic strand be of an elastic nature that does
not exceed its elastic limit during the deployment of the vascular
tubular member of the present invention. The wire in another
embodiment could undergo plastic deformation during the deployment
of the vascular tubular member. This straight metallic strand can
be woven in the circumferential direction forming a straight
circumferential metallic strand, or it can be woven in the axial
direction forming a straight axial metallic strand. The metallic
strand can also undergo a thermal, mechanical, or chemical forming
process that can heat set, mechanically set, or chemically set the
metallic strand to have local bends, helices, or curves in it. This
curved metallic strand will have the characteristic that it can
either stretch or compress in its overall axial direction. This
curved metallic strand can be woven in a circumferential direction
forming a curved circumferential metallic strand, or it can be
woven in an axial direction forming a curved axial metallic strand.
When woven in an axial direction, the curved wire is held under
tension and is therefore held in a straight conformation. Upon
release of the metallic strand, it forms the curved shape that was
formed into the metallic strand prior to weaving. Circumferentially
weaving a curved metallic strand requires additional effort due to
the tortuous pathway followed by the strand during the weave.
[0038] The vascular tubular member wall structure of the present
invention can include a woven tubular structure consisting of
curved and straight, polymeric and metallic strands in the
circumferential and axial directions. In one structure straight
circumferential polymeric strands and one or more straight
circumferential metallic strands are interwoven circumferentially
and straight axial polymeric strands are woven axially. This
structure is easy to form and has good hoop strength that will
resist kinking due to the metallic component. The folded tubular
section has good approximation between the inner, center, and outer
walls since only the polymeric strands are extending axially
allowing the circumferential fold lines to have a very small radius
of curvature.
[0039] In another vascular tubular member wall structure additional
straight axial metallic strands are interwoven with the straight
axial polymeric strands of the structure just presented above. The
additional straight axial metallic strands provide the folded
tubular section with the characteristic that resists wrinkling in
the folded tubular section. A tubular double weave can be used
whenever two metal strands form a crossover point. One of the metal
strands can be brought out of the plane of the weave prior to the
crossover point and reenter the plane of the weave after the
crossover point. The weaving plane is thus continuous without one
of the metal strands and leakage at that crossover point will not
occur. The additional straight axial metallic strands offer axial
strength against compressive deformation but can cause the vascular
tubular member to become stiff and more difficult to negotiate the
tortuous turns of the iliac and femoral arteries.
[0040] In still another vascular tubular member wall structure a
curved axial metallic strand is interwoven with straight axial
polymeric strands in the vascular tubular member wall structure
just presented above instead of straight axial metallic strands.
The curved axial metallic strands provide a benefit to the folded
tubular section to resist wrinkling during the unfolding process.
The curved axial metallic strands also provide the vascular tubular
member with good axial support against compressive forces generated
by the thrombus and other physiological forces that can be placed
upon the vascular tubular member. The curved axial metallic strands
can compress elastically and thereby will not provide this vascular
tubular member wall structure with good flexibility and will resist
vascular tubular member kinking.
[0041] In yet another vascular tubular member wall structure
straight circumferential polymeric strands are interwoven with one
or more curved circumferential metallic strands in the
circumferential direction and straight axial polymeric strands are
interwoven with curved axial metallic strands in the axial
direction. The curved circumferential metallic strands found in
this structure allows the folded tubular section to unfold with
greater ease due to their ability to elongate diametrically as, for
example, one curved circumferential metallic strand located in an
inner or outer wall passes adjacent to another curved
circumferential metallic strand located in the center wall. The
curves or bends in the curved circumferential metallic strands also
allows the vascular tubular member to expand out uniformly to its
deployed diameter which can be smaller than the equilibrium
diameter of the vascular tubular member and provide uniform contact
with the aortic wall.
[0042] In one more vascular tubular member wall structure curved
circumferential polymeric strands are interwoven with one or more
straight circumferential metallic strands in the circumferential
direction and straight axial polymeric strands are interwoven with
curved axial metallic strands in the axial direction. The curved
circumferential polymeric strands provide an amount of
circumferential stretch in the diametric direction. The other
components of the weave restrict excessive circumferential stretch.
This vascular tubular member structure can also be modified
slightly to provide an additional characteristic. Near the proximal
end of the tubular means the straight circumferential metallic
strands can be eliminated thereby allowing the vascular tubular
member to expand to a larger circumference. This circumferential
expansion allows the vascular tubular member of the present
invention to accommodate a reasonable tolerance in the estimated
aortic neck diameter of a few millimeters. Similar circumferential
accommodation also applies to the iliac artery.
[0043] Accommodation of the estimated aortic diameter with a
vascular tubular member of a fixed non-flexible wall material with
a maximum diameter can also be accomplished by ensuring that the
vascular tubular member chosen can expand to a slightly larger
diameter than the aortic diameter. Any embodiment of vascular
tubular member wall structure of this disclosure can provide this
characteristic. Any excess graft wall material will result in a
wrinkle or fold if the perimeter of the tubular member is slightly
larger than the perimeter of the aorta, for example. Provided that
this wrinkle or fold is held tightly against the aortic wall by the
proximal attachment anchor, leakage at the proximal site will not
occur.
[0044] In yet one more vascular tubular member wall structure
curved circumferential polymeric strands are interwoven with one or
more curved circumferential metallic strands in one direction and
the axial direction is the same as the vascular tubular member wall
structure just described above. This structure offers the ability
to stretch in the circumferential direction to a limited extent
controlled by the amount of curvature provided to the
circumferential strands. This vascular tubular member wall
structure provides good anti-kink characteristics, good axial
support against compression, good flexibility, and will accommodate
a reasonable tolerance in the aortic neck diameter, and a tolerance
on the iliac artery diameter.
[0045] In still one more vascular tubular member wall structure
curved circumferential polymeric strands are interwoven with one or
more curved circumferential metallic strands in one direction and
the axial direction contains curved axial polymeric strands
interwoven with curved axial metallic strands. This structure
offers the ability to stretch in the circumferential and axial
direction to a limited extent controlled by the amount of curvature
provided to the circumferential and axial strands, respectively.
This structure can extend in each direction throughout the entire
tubular means. This vascular tubular member wall structure provides
good anti-kink characteristics, good axial support against
compression, good flexibility, and will accommodate a reasonable
tolerance in the aortic neck diameter, and a tolerance on the iliac
artery diameter.
[0046] All of the vascular tubular member wall structures presented
in this disclosure can be formed with the axial metallic strands
being directed with an augmented amount of helical turn. This is
accomplished by taking metallic strand out of the weaving plane,
stepping over to a new site that is displaced circumferentially,
and inserting the metallic strand back into the plane of the weave.
This stepping over process allows the axial metallic strand to
assume a helical pathway along the axial direction of the vascular
tubular member. This augmented amount of helical turn is in
addition to the gradual helical turn naturally found in the axially
oriented metallic strands due to their natural desire to orient
perpendicular to the generally circumferential strands which also
have a slight helical turn since they are wound in a continuous
helix. The augmented helical turn of the metallic strands in the
generally axial direction provides the vascular tubular member with
an ability to bend without kinking even when straight metallic
strands are used in the axial direction. Enhanced helical turn in
the circumferential direction can also be accomplished by weaving
two or more metallic strands into the circumferential weave. This
can provide a steeper angel for the helical wind and provide
additional axial flexibility without kinking.
[0047] In a preferred embodiment curved polymeric strands are wound
in both the circumferential and axial direction to provide the
vascular tubular member with a supple feel and good bending
characteristics without kinking. For simplicity of manufacturing,
one or more straight metallic strands are wound in the
circumferential direction. Either curved metallic strands or
straight metallic strands with the step over characteristic
described above is used in the axial direction to provide the
necessary compressive strength as well as provide good flexibility
to the vascular tubular member. An entire straight or bifurcated
vascular tubular member can be formed from a single contiguous
woven material comprised of the polymeric and metallic strands
described above. The vascular tubular member is woven without seam
in its proximal, folded or distal section. For the bifurcated
tubular member this is accomplished by splitting the number of
strands that extend axially such that approximately half of those
present in the main trunk extend down one proximal leg and half
extend down the other proximal leg.
[0048] The vascular tubular member wall structure of the present
invention can also be formed from a braiding process wherein
straight polymeric and straight metallic strands are braided in a
right hand spiral forming straight right spiral polymeric strands
and straight right spiral metallic strands. These strands can be
made with localized bends or curves in them as described earlier,
and these strands can be braided into a right hand spiral to form
curved right spiral polymeric strands and curved right spiral
metallic strands. Similarly the straight and curved, polymeric and
metallic strands can be braided into a left hand spiral.
[0049] In one vascular tubular member wall braided structure a
straight right spiral polymeric strand and a straight right spiral
metallic strand are interbraided together in one direction and a
straight left spiral polymeric strand and a straight left spiral
metallic strand are interbraided in the opposite direction. The
braiding process provides some ability for this wall structure to
accommodate reasonable tolerances in the estimation of the proximal
aortic neck diameter in order to provide a good diametric fit
between the vascular tubular member and the proximal aortic neck.
The presence of the straight and curved metallic strands provides
good axial and circumferential strength and stability against
compression in the radial or axial direction in comparison to other
prior art materials of construction.
[0050] In other vascular tubular member embodiments the braided
structure can involve either curved metallic strands or curved
polymeric strands. These curved metallic or polymeric strands will
provide the vascular tubular member with a greater flexibility due
to the ability of these metallic strands to compress as the
vascular tubular member is exposed to a tortuous pathway.
[0051] It is understood that the woven and braided vascular tubular
member wall structures presented are not intended to be complete
and that other combinations of straight and curved, polymeric and
metallic strands can be used with weaving or braiding with the
associated characteristics and advantages that have been described
or taught in this disclosure.
[0052] The bifurcated tubular member used in the treatment of
abdominal aortic aneurysm described in this invention can have a
proximal attachment anchor attached at the proximal end of the
bifurcated main trunk. This attachment anchor provides a
circumferential expansion and attachment to the aorta without
significant change in axial length. This small axial length change
allows this attachment anchor to be placed very near to the renal
arteries with precision and reduce the likelihood for distal
migration of the vascular tubular member. A greater number of barbs
can be placed on the attachment anchor due to the geometry of the
attachment anchor which has a short axial length and involves a
hinge to supply the outward forces of the attachment anchor. The
increased number of barbs will better hold the vascular tubular
member to the aorta around the entire circumference.
[0053] The bifurcated folded tubular member of the present
invention can also have a proximal attachment anchor that is
displaced proximally from the proximal end of the main trunk. The
displaced attachment anchor can be joined to the bifurcated main
trunk by the metal strands that are woven axially or helically into
the vascular tubular member or by the metal strands that are
braided into the vascular tubular member. The displaced proximal
attachment anchor is intended in one embodiment to provide
attachment proximal to the renal arteries in a region of the aorta
that is significantly proximal to the aneurysmal region of the
aorta. Since many abdominal aortic aneurysms occur adjacent to the
renal vessels and generally distal to the renal vessels, it is
sometimes necessary to find a proximal attachment site that is
proximal to the renal arteries. The displaced proximal attachment
anchor will provide this attachment capability and prevent any
distal migration of the intravascular tubular member. The small
metallic strands that connect the displaced attachment anchor to
the main trunk of the intravascular tubular member can cross over a
renal artery without causing a significant thrombotic or occlusive
effect. The metallic strands are positioned around the
circumference to provide the main trunk with support from the
attachment anchor along its entire circumference. Only a minimal
number of metallic strands extend to the displaced attachment
anchor in order to reduce the chances for thrombus formation at the
entrances to the renal arteries. The number of strands can range
from two to approximately sixteen. An additional proximal
attachment anchor may be attached to the open proximal end of the
main trunk in addition to the displaced attachment anchor to
provide a tight leak-free seal with the aorta. The displaced
attachment anchor can have barbs to enhance attachment to the aorta
or it can be an attachment anchor without barbs as described
earlier. The metallic strands can be attached to selected securing
sites of the attachment anchor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0054] Other objects of the present invention and many of the
attendant advantages of the present invention will be readily
appreciated as the same becomes better understood by reference to
the following detailed description when considered in connection
with the accompanying drawings, in which like reference numerals
designate like parts throughout the figures thereof and
wherein:
[0055] FIG. 1A is a sectional view of a vascular tubular member
implanted within an abdominal aortic aneurysm;
[0056] FIG. 1B is a sectional view of an intravascular tubular
member implanted in a bifurcated abdominal aortic aneurysm;
[0057] FIG. 2A is a sectional view of a straight intravascular
folded tubular member in a partially deployed state;
[0058] FIG. 2B is a sectional view of a straight intravascular
folded tubular member in a fully deployed state;
[0059] FIG. 2C is a cross sectional view of a straight
intravascular folded tubular member near the inlet end in a
nondeployed state;
[0060] FIG. 2D is a cross sectional view of a straight
intravascular folded tubular member near the outlet end in a
nondeployed state;
[0061] FIG. 2E is a sectional view of a straight intravascular
folded tubular member in an unfolded state;
[0062] FIG. 3 is an isometric view of a straight intravascular
folded tubular member in a nondeployed state with an attachment
means at inlet and outlet ends;
[0063] FIG. 4A is a sectional view of a bifurcated intravascular
folded tubular member in a partially deployed state;
[0064] FIG. 4B is a sectional view of a bifurcated intravascular
folded tubular member in a fully deployed state;
[0065] FIG. 4C is a sectional view of a bifurcated intravascular
folded tubular member in a nondeployed state within a delivery
sheath near the inlet end;
[0066] FIG. 4D is a sectional view of a bifurcated intravascular
folded tubular member in a nondeployed state within a delivery
sheath near the outlet ends;
[0067] FIG. 4E is a sectional view of a bifurcated intravascular
folded tubular member in a nondeployed state on a balloon
dilitation catheter near the inlet end;
[0068] FIG. 4F is a sectional view of a bifurcated folded tubular
member in an unfolded state;
[0069] FIG. 5 is a partially sectioned view of a bifurcated folded
tubular member in a nondeployed state with attachment means at the
inlet and outlet ends;
[0070] FIG. 6 shows a sectional view of a folded tubular section in
a nondeployed state with a bonding agent applied;
[0071] FIG. 7A is a schematic sectional view of the folded tubular
section in a nondeployed state;
[0072] FIG. 7B is a schematic sectional view of the folded tubular
section unfolded from the circle to the point-down triangle;
[0073] FIG. 7C is a schematic sectional view of the folded tubular
section unfolded from the square to the point-up triangle;
[0074] FIG. 7D is a schematic sectional view of the folded tubular
section unfolded evenly;
[0075] FIG. 7E is a schematic sectional view of the folded tubular
section with wrinkling;
[0076] FIG. 8 is a sectional view of a folded tubular section with
holding pins;
[0077] FIG. 9A is an isometric view of an attachment anchor with
one hinge per node in a nondeployed state;
[0078] FIG. 9B is an isometric view of an attachment anchor with
one hinge per node in a deployed state;
[0079] FIG. 9C is an enlarged detailed isometric view of a node of
an attachment anchor with one hinge;
[0080] FIG. 9D is a perspective view of an attachment anchor with
an oval attachment anchor surface;
[0081] FIG. 10A is an isometric view of an attachment anchor with
two hinges per node in a nondeployed state;
[0082] FIG. 10B is an isometric view of an attachment anchor with
two hinges per node in a deployed state;
[0083] FIG. 10C is an enlarged detailed isometric view of a node of
an attachment anchor with two hinges;
[0084] FIG. 10D is a perspective view of an attachment anchor with
nodes and struts in a closed configuration in a nondeployed
state;
[0085] FIG. 10E is a perspective view of an attachment anchor with
nodes and struts in a closed configuration in a deployed state;
[0086] FIG. 11A is an isometric view of an attachment anchor with
barbs in a nondeployed state;
[0087] FIG. 11B is an enlarged view of a portion of an attachment
anchor with barbs in a nondeployed state;
[0088] FIG. 11C is an isometric view of an attachment anchor with
barbs in a deployed state;
[0089] FIG. 11D is an enlarged view of a portion of an attachment
anchor with barbs in a deployed state;
[0090] FIG. 12A is an isometric view of attachment anchors
positioned at an inlet end and an outlet end of an intravascular
tubular member;
[0091] FIG. 12B is an isometric view of attachment anchors
positioned at an inlet end and an outlet end of a straight
intravascular folded tubular member;
[0092] FIG. 12C is a partially sectioned view of attachment anchors
positioned an inlet and outlet ends of a bifurcated intravascular
folded tubular member;
[0093] FIG. 13A is a perspective view of a woven vascular tubular
member;
[0094] FIG. 13B is a perspective view of a woven multifilament
strand wall structure for a vascular tubular member;
[0095] FIG. 13C is a perspective view of a woven monofilament
strand wall structure;
[0096] FIG. 13D is a perspective view of a multifilament strand
formed of filaments;
[0097] FIG. 13E is a perspective view of an expanded
polytetrafluoroethylene filament;
[0098] FIG. 13F is a perspective view of a straight multifilament
strand formed of straight filaments;
[0099] FIG. 13G is a perspective view of a curved multifilament
strand formed of curved filaments;
[0100] FIG. 13H is a perspective view of a curved expanded
polytetrafluoroethylene filament formed of microfilaments;
[0101] FIG. 13I is a perspective view of a vascular tubular member
formed of expanded polytetrafluoroethylene strands;
[0102] FIG. 13J is a perspective view of a wall structure formed of
metallic strands woven along with polymeric multifilament
strands;
[0103] FIG. 13K is a perspective view of a straight monofilament
strand;
[0104] FIG. 13L is a perspective view of a curved monofilament
strand;
[0105] FIG. 13M is a perspective view of a woven wall structure of
flattened metallic strands;
[0106] FIG. 14 is a representation of a vascular tubular member
with a woven wall structure having straight axial metallic,
straight axial polymeric, straight circumferential metallic, and
straight circumferential polymeric strands;
[0107] FIG. 15 is a perspective view of double weaving at a metal
to metal crossover point;
[0108] FIG. 16A is a representation of a vascular tubular member
with a woven wall structure having straight axial polymeric,
straight circumferential polymeric, and straight circumferential
metallic strands;
[0109] FIG. 16B is a representation of a vascular tubular member
with a woven wall structure having straight axial polymeric, curved
axial metallic, straight circumferential polymeric, and straight
circumferential metallic strands;
[0110] FIG. 16C is a representation of a vascular tubular member
with a woven wall structure having straight axial polymeric, curved
axial metallic, straight circumferential polymeric, and curved
circumferential metallic strands;
[0111] FIG. 17A is a representation of a vascular tubular member
with a woven wall structure having straight axial polymeric, curved
axial metallic, curved circumferential polymeric, and straight
circumferential metallic strands;
[0112] FIG. 17B is a representation of a vascular tubular member
with a woven wall structure having straight axial polymeric, curved
axial metallic, curved circumferential polymeric, and curved
circumferential metallic strands;
[0113] FIG. 17C is a representation of a vascular tubular member
with a woven wall structure having curved axial polymeric, curved
axial metallic, curved circumferential polymeric, and curved
circumferential metallic strands;
[0114] FIG. 18A is a representation of a vascular tubular member
with a woven wall structure having curved circumferential
polymeric, straight circumferential metallic, curved axial
polymeric, and straight axial metallic strands having a
circumferential step-over;
[0115] FIG. 18B is a representation of a vascular tubular member
with a woven wall structure having curved circumferential
polymeric, curved axial polymeric, straight circumferential
metallic, and curved axial metallic strands with augmented helical
turn;
[0116] FIG. 19 is a representation of a vascular tubular member
with a braided wall structure having left and right spirals of
multifilament polymeric and monofilament metallic strands;
[0117] FIG. 20 is a partially sectioned view of an intravascular
tubular member formed of a woven wall structure with multifilament
polymeric strands and axially directed metallic strands interwoven
and a displaced attachment anchor;
[0118] FIG. 21 is an intravascular folded tubular member formed
with a woven wall structure of multifilament polymeric strands
interwoven along with monofilament metallic strands;
[0119] FIG. 22 is an intravascular folded tubular member formed
with a woven wall structure formed entirely of multifilament
polymeric strands;
[0120] FIG. 23 is a bifurcated intravascular folded tubular member
formed of a woven wall structure of multifilament polymeric strands
interwoven along with monofilament metallic strands and having
attachment anchors at the inlet and outlet ends.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0121] The present invention is a vascular implant intended for use
to repair injured arteries or veins of the body. Such injuries can
include aneurysms, stenoses, diffuse atherosclerosis, traumatic
injury, or other injury that requires vascular repair or bypassing
of the vessel. The vascular implant includes a vascular tubular
member that conveys blood flow from a region of the repaired blood
vessel proximal to the vessel injury to a region distal to the
vessel injury. The vascular tubular member is primarily intended to
be an intravascular tubular member for intravascular use using
percutaneous access to the interior of the vessel or a minimal
surgical cutdown to access a blood vessel either proximal or distal
to the injured vessel that is to be repaired. The intravascular
tubular member is entered into the proximal or distal blood vessel
in a smaller diameter nondeployed conformation and is delivered to
the site of the vessel injury where it enlarges to a larger
diameter providing a passage for blood flow. An embodiment of the
present invention is an intravascular folded tubular member that
also enlarges in length following delivery to the site of vessel
injury. One intravascular repair application that is in particular
need of improvement is the repair of aortic aneurysms and most
common the repair is one involving the abdominal aorta. The present
invention is well suited to provide improvements in treating
abdominal aortic aneurysms although it can also be used effectively
in the repair of vessels throughout the body. The intravascular
tubular member can include an attachment means attached to the
proximal end or distal end of the intravascular tubular member to
hold the intravascular tubular member firmly into contact with the
wall of the injured blood vessel, prevent blood leakage at the
proximal end or distal end, and prevent distal migration of the
intravascular tubular member. The vascular implant of the present
invention includes an attachment means that can be used with other
prior art intravascular devices in addition to the intravascular
tubular member of the present invention. The vascular tubular
member includes not only the intravascular tubular member but also
includes a surgical vascular graft that can be implanted surgically
for repair of vascular injury. A vascular tubular member can
include other tubular members that can have a generally tubular
shape and have application in the repair of blood vessels. A woven
and braided wall structure is presented that has application to
both surgical vascular grafts as well as intravascular tubular
members. It is understood that the present invention is not limited
to the embodiments presented in this disclosure. The present
invention can also be applied to other tubular organs of the body
besides blood vessels. Such tubular organs include but are not
limited to the intestines, esophagus, trachea, bile ducts, or other
ducts of the body.
[0122] FIGS. 1A and 1B show a side and frontal view of abdominal
aortic aneurysms 5. The abdominal aortic aneurysm 5 can be used as
an example of an arterial injury that can be treated with one or
more embodiments of the present invention. Distension of the
abdominal aorta 10 often extends from distal to the left renal vein
15 to the common iliac artery 20, external iliac artery 25, common
femoral artery 30 or to more than one artery. The left renal vein
15 follows a path anterior to the aorta from the left kidney 35 to
the inferior vena cava 40. The left renal vein 15 can provide some
support to assist the abdominal aorta 10 from further distension
proximal to the left renal artery 45 and right renal artery 50. A
blood flow native lumen 53 extends from the suprarenal aorta 55
through the distended abdominal aorta 10, through the aorto-iliac
bifurcation 57, and into each common iliac artery 20, each external
iliac artery 25, and each common femoral artery 30. Thrombus 60
fills the cavity that exists between the blood flow native lumen 53
and the abdominal aortic wall 70. Lumbar arteries 75 located on the
posterior side of the aorta and other arteries of the region can be
occluded due to the presence of thrombus 60 or may remain patent
depending upon the severity of the aneurysm. Each internal iliac
artery 80 is often patent and should be allowed to remain patent
when repairing an abdominal aortic aneurysm 5 if possible. An
embodiment of the vascular implant 82 of the present invention is
shown in FIG. 1A. The vascular implant 82 can include a vascular
tubular member 83 that can be placed surgically within the native
lumen or the vascular implant 82 can be an intravascular tubular
member 85 that could have a bifurcation and could be placed
percutaneously or with minimal surgical cutdown through a distal or
other connecting vessel to reach the site of vessel injury as shown
in FIG. 1B. In FIG. 1B the intravascular tubular member could have
been inserted by a sheath placed in one of the common femoral
arteries 30 and delivered to the abdominal aorta 10. The
intravascular tubular member 85 can have an attachment means 87
attached to it to help provide a seal between the intravascular
tubular member 85 and the native lumen 53 and help reduce migration
of the intravascular tubular member 85. The vascular implant 82 can
include the attachment means 87 which can be used with the
intravascular tubular member 85 of the present invention or it can
be used with other stent-graft devices. The intravascular tubular
member 85 can be bifurcated with a bifurcation that extends from a
proximal aortic neck 90 to each common iliac artery 20, common
femoral artery 30, or other distal artery. The intravascular
tubular member 85 can also have other configurations and
embodiments which will be explained further in this disclosure.
Folded Tubular Members
[0123] A first embodiment of the present invention (see FIGS.
2A-2D) is a straight intravascular folded tubular member 95 for
repairing an arterial lesion, an aneurysm, or other vascular injury
found in a blood vessel. The straight intravascular folded tubular
member 95 is intended to provide a blood flow passage 100 from a
region of the blood vessel proximal to the vascular injury to a
region of blood vessel distal to the vascular injury. The preferred
method of deploying the straight intravascular folded tubular
member 95 is to insert it through a percutaneous access through a
sheath as is well known in the industry or with a small surgical
cutdown to provide direct access to a blood vessel located either
proximal or distal to the vascular injury.
[0124] FIG. 2A shows the straight intravascular folded tubular
member 95 in a radially deployed state with a radially deployed
inlet end diameter 105, a radially deployed outlet end diameter
110, and a straight nondeployed tubular member length 115. The
straight intravascular folded tubular member 95 has a straight
proximal tubular section 120, a folded tubular section 125, a
distal tubular section 130, an inner surface 135 and an outer
surface 140. The inner surface 135 and outer surface 140, and
intravascular tubular member wall 143 each extend continuously from
an inlet end 145 through the straight proximal tubular section 120,
through the folded tubular section 125, and through the distal
tubular section 130 to an outlet end 148 of the folded tubular
section 125. The continuous intravascular tubular member wall 143
can have attachments between the straight proximal tubular section
120 and the folded tubular section 125 and between the folded
tubular section 125 and the distal tubular section 130 although it
is preferred to form the intravascular tubular member wall 143 with
each of these sections joined contiguously from the same material
without attachments between sections. The inner surface 135 of the
straight proximal tubular section 120 and the distal tubular
section 130 is a blood flow surface in contact with blood flow. A
portion of the inner surface of the folded tubular section 125 is a
blood flow surface in contact with blood flow. The straight
proximal tubular section 120 has inlet end 145 that provides
passage for blood flow into the straight proximal tubular section
120 and into the straight intravascular folded tubular member 95.
The straight proximal tubular section 120 has a straight
nondeployed proximal tubular section length 150. The straight
proximal tubular section 120 is joined either contiguously or with
an attachment to the folded tubular section 125. The folded tubular
section 125 is formed from a continuous tube that is folded back
and forth upon itself to form three separate walls, a folded
tubular section outer wall 155, a folded tubular section center
wall 160, and a folded tubular section inner wall 165. The folded
tubular section inner wall 165 is joined either contiguously or
with attachment to a straight proximal tubular section wall 170 to
form a continuous wall. The folded tubular section 125 has a
proximal circumferential fold line 175 and a distal circumferential
fold line 180 and has a nondeployed folded tubular section length
185 extending from the proximal circumferential fold line 175 to
the distal circumferential fold line 180. The portion of the
intravascular tubular member wall 143 that forms the folded tubular
section 125 has an upstream end 187 and a folded tubular section
downstream end 188. The straight proximal tubular section wall 170
is joined to the folded tubular section upstream end 187 and the
distal tubular section wall 190 is joined to the folded tubular
section downstream end 188. In the folded tubular section 125, a
portion of the inner surface 135 of the straight intravascular
folded tubular member 95 is in apposition with another adjoining
portion of the inner surface 135. Similarly, in the folded tubular
section 125 a portion of the outer surface 140 is in apposition
with another adjoining portion of the outer surface 140. The folded
tubular section outer wall 155 is joined either contiguously or
with an attachment to a distal tubular section wall 190 of the
distal tubular section 130 to form a continuous wall. The distal
tubular section 130 has an outlet end 148 to provide passage of
blood flow out of the distal tubular section 130 and out of the
straight intravascular folded tubular member 95. The distal tubular
section 130 has a nondeployed distal tubular section length 200
extending from the folded tubular section 125 to the outlet end
148. The straight intravascular folded tubular member 95 has a
straight nondeployed tubular member length 115 that extends from
the inlet end 145 to the outlet end 148. The straight intravascular
folded tubular member 95 has a blood flow passage 100 which
provides passage of blood flow from the inlet end 145 to the outlet
end 148. The distal circumferential fold line 180 is in contact
with the blood flow passage 100 such that shear forces acting by
the blood onto the inner surface 135 will not act to generate
separation between the three walls of the folded tubular section
125. The distal tubular section 130 has a nondeployed distal
tubular section length 200 that can provide significant length in
accordance with the length requirements for a specific vascular
application. Alternately, it is understood that the nondeployed
distal tubular section length 200 can be very short such that it
includes essentially only the outlet end 148 without any
significant length.
[0125] FIG. 2B shows the straight intravascular folded tubular
member 95 in a fully deployed state or in an implanted state with a
radially deployed inlet end diameter 105, a radially deployed
outlet end diameter 110, and a straight deployed tubular member
length 205. The inlet end 145 and outlet end 148 have been extended
in axial position with respect to each other. To accomplish the
longer straight deployed tubular member length 205 the folded
tubular section 125 has unfolded such that its deployed folded
tubular section length 210 is shorter in the fully deployed state
or implanted state (see FIG. 2B) than the nondeployed folded
tubular section length 185 in the non-axially deployed state shown
in FIG. 2A. The straight deployed proximal tubular section length
215 and the deployed distal tubular section length 220 are longer
in the deployed state as shown in FIG. 2B than the straight
nondeployed proximal tubular section length 150 and the nondeployed
distal tubular section length 200, respectively in the non-axially
deployed state. It is possible for the deployed distal tubular
section length 220 to have increased more in length than the
straight deployed proximal tubular section length 215 as the
straight intravascular folded tubular member 95 goes from a
partially deployed state to a fully deployed state. Alternately,
both the straight deployed proximal tubular section length 215 and
deployed distal tubular section length 220 could have increased the
same amount as the straight deployed tubular member length has
extended from a partially deployed state to a fully deployed state
as will be explained further later. All reference numerals
correspond to those elements previously or otherwise described.
[0126] FIGS. 2C and 2D show cross sectional views of the straight
intravascular folded tubular member 95 in a nondeployed state, a
non-radially deployed state, or insertion state. The length of the
straight intravascular folded tubular member in FIGS. 2C and 2D is
the same as in FIG. 2A. In one embodiment for delivering or
inserting a self-expanding straight intravascular folded tubular
member 95, for example, an outer delivery sheath 225 holds the
straight intravascular folded tubular member 95 with a smaller
insertion diameter or nondeployed inlet end diameter 230 and with a
smaller insertion diameter or nondeployed outlet end diameter 235.
To deliver the straight intravascular folded tubular member 95 to
the site of the vascular injury, the delivery sheath 225 containing
the straight intravascular folded tubular member 95 is entered into
a vessel either proximal or distal to the vascular lesion. Upon
removal from the delivery sheath 225, the straight intravascular
folded tubular member 95 expands from the nondeployed state to form
the partially deployed state with a larger radially deployed inlet
end diameter 105 and radially deployed outlet end diameter 110 as
shown in FIG. 2A. Following delivery of the straight intravascular
folded tubular member 95 to the site of the lesion, the straight
intravascular folded tubular member 95 is extended from a straight
nondeployed tubular member length 115 to an appropriate straight
deployed tubular member length 205 representative of an implanted
state. Mechanical dilitation of the tubular member can be further
employed if needed such as with a balloon dilitation catheter to
expand the straight intravascular folded tubular member 95 to its
radially deployed inlet end diameter 105 and radially deployed
outlet end diameter 110 to ensure that the straight intravascular
folded tubular member has attained a larger deployed diameter 237
(see FIGS. 2A and 2B). The delivery sheath 225, in addition to a
balloon dilitation catheter, or other delivery system means can be
used to deliver the straight intravascular folded tubular member 95
to the site of vascular injury and deploy it from a nondeployed
state or insertion state with a smaller insertion diameter or
nondeployed diameter to a deployed state or implanted state with a
larger deployed diameter 237 or implanted diameter. The straight
intravascular folded tubular member can also be a
balloon-expandable device. In this case the straight intravascular
folded tubular member, either with or without an attachment means
can be mounted in a nondeployed state onto the balloon of a balloon
dilitation catheter. Upon delivery to the site of the lesion, the
balloon can be expanded to cause the straight intravascular folded
tubular member to assume its radially deployed state.
[0127] FIG. 2E shows a straight intravascular folded tubular member
95 in an unfolded state with a straight unfolded tubular member
length 240 prior to forming the folded tubular section 125 shown in
FIGS. 2A and 2B. The straight intravascular folded tubular member
95 can be formed out of any material used in vascular grafts, in
stent-grafts, or implanted vascular conduits such as tubular
expanded polytetrafluoroethylene (ePTFE), woven expanded
polytetrafluoroethylene fibers, woven or knitted polyester,
polyurethane, silicone, or other materials such as composite woven
or braided materials presented later in this disclosure.
[0128] The straight intravascular folded tubular member 95 can have
but is not required to have an attachment means 87 at the inlet and
outlet end 148 as shown in FIG. 3. This attachment means can be a
prior art stent used for vascular implant. Such an attachment means
87 if present generally serves to hold the straight intravascular
folded tubular member 95 in place and ensure a leak free fit with
the native vessel proximal or distal to the vessel injury. The
straight intravascular folded tubular member 95 can be placed
within a blood vessel and with the inlet end 145 and outlet end 148
being attached to the native vessel using a separate prior art
stent or attachment means of any type that is placed near the inlet
end 145 and outlet end 148 to form an attachment with the native
vessel. If appropriate, a surgical cutdown could be conducted and
sutures used to hold the inlet end 145 and outlet end 148 of the
straight intravascular folded tubular member 95 in place with a
leak free seal. The straight intravascular folded tubular member 95
could also be formed from a material that maintained a tubular or
cylindrical shape with an outward extending force and did not
require an attachment means. Existing vascular graft materials
including polyurethane, silicone, and others are capable of
providing this characteristic and may not require an additional
attachment means in some implant situations. Such implant
situations include repair of blood vessels with luminal injury that
would benefit by a vascular graft but with adequate vessel
integrity and anatomy such that graft migration and sealing are not
of acute concern.
[0129] It is often times preferable to include an attachment means
87 to ensure a tight seal between the straight intravascular folded
tubular member 95 and the vessel wall and to prevent migration of
the straight intravascular folded tubular member 95. An attachment
anchor 245 which is included in the present invention and is
discussed in more detail later in this disclosure is shown attached
to the inlet end 145 and outlet end 148 of the straight folded
tubular member 95. FIG. 3 shows the straight intravascular folded
tubular member 95 in a deployed state with the attachment anchor
245 containing barbs 250 attached to the straight proximal tubular
section 120 near the inlet end 145 with securing fibers 255 or
other securing means. Almost any attachment means such as a stent
found in the prior art can be used as the attachment means for the
inlet end 145 and outlet end 148 of the straight intravascular
folded tubular member 95. The attachment anchor 245 of the present
invention shown in FIG. 3 can provide more enhanced anchoring
properties than found with other prior art attachment means and
will be discussed later in this disclosure. The attachment anchor
245 with barbs 250 is positioned on the inner surface 135 of the
straight intravascular folded tubular member 95 such that it
forcibly holds the straight intravascular folded tubular member 95
outward against the vessel wall after the attachment anchor 245 has
been deployed to a larger diameter. The attachment anchor 245 has
barbs 250 that extend outward to provide enhanced anchoring of the
straight intravascular folded tubular member 95 to the vessel wall.
This anchoring helps to prevent migration of the straight
intravascular folded tubular member 95 and in the case of abdominal
aortic aneurysm repair can help to support the aortic wall from
further aneurysmal dilitation. The attachment anchor 245 without
barbs 250 is shown attached to the distal tubular section 130 at or
near the outlet end 148 with securing fibers 255. The attachment
anchor 245 is positioned on the inside of the straight
intravascular folded tubular member 95 such that it forcibly holds
the straight intravascular folded tubular member 95 outward against
the vessel wall. For ease of description, the straight
intravascular folded tubular member 95 is shown with an attachment
anchor 245 with barbs 250 attached to the straight proximal tubular
section 120 and an attachment anchor 245 without barbs 250 attached
to the distal tubular section 130. Either the straight proximal
tubular section 120 or the distal tubular section 130 could have
the attachment anchor 245 with or without barbs 250 attached and
still be within the teachings of the present disclosure.
[0130] Another embodiment of the present invention is a bifurcated
intravascular folded tubular member 260 shown in FIGS. 4A-4D and
described collectively below. This embodiment is intended for
vascular repair of a blood vessel trunk that has a bifurcation
wherein one or both native vessel legs bifurcating off of the
vessel trunk are also in need of repair. Blood flow from the common
blood vessel trunk of the vessel proximal to the site of vessel
injury into the bifurcated intravascular folded tubular member 260.
The bifurcated intravascular folded tubular member 260 has an inlet
end 145 that provides passage for blood flow into the bifurcated
intravascular folded tubular member 260 (see FIG. 4B). The
bifurcated intravascular folded tubular member 260 has two outlet
ends 148 that provide passage for blood flow out of the bifurcated
intravascular folded tubular member 260 into two distal vessels
located distal to the vessel lesion. One common application for
this embodiment is in the repair of abdominal aortic aneurysms
where one or both common iliac, external iliac, or femoral arteries
are involved in the aneurysmal dilation of the vessel wall. The
bifurcated intravascular folded tubular member 260 has a bifurcated
proximal tubular section 265 with an inlet end 145, a bifurcated
main trunk 270 joined either contiguously or with an attachment to
two proximal leg tubes 275. The bifurcated intravascular folded
tubular member 260 has an inner surface 135 and an outer surface
140. Each of the proximal leg tubes 275 are joined either
contiguously or with an attachment to a folded tubular section 125.
Each folded tubular section 125 is joined either contiguously or
with an attachment to a distal tubular section 130. Each distal
tubular section 130 has an outlet end 148 that provides passage for
blood flow out of each distal tubular section 130 and out of the
bifurcated intravascular folded tubular member 260.
[0131] The bifurcated intravascular folded tubular member 260 is
shown in a partially deployed state in FIG. 4A. The inlet end 145
has a larger radially deployed inlet end diameter 105 and each
outlet end 148 has a larger radially deployed outlet end diameter
110. A continuous intravascular tubular member wall 143 extends
from the inlet end 145 to each outlet end 148. The continuous
intravascular tubular member wall 143 can have attachments between
the bifurcated proximal tubular section 265, the folded tubular
section 125, and the distal tubular section 130 of the
intravascular tubular member wall 143 or the intravascular tubular
member wall 143 can be contiguous without attachments. The radially
deployed bifurcated intravascular folded tubular member 260 has a
shorter bifurcated nondeployed tubular member length 280 than the
bifurcated deployed tubular member length 290. The bifurcated
intravascular folded tubular member 260 shown in this embodiment is
similar to the straight intravascular folded tubular member 95
shown in FIGS. 2A-2D except that the present embodiment has a
bifurcated proximal tubular section 265 that is bifurcated and it
has two folded tubular sections 125 joined to the bifurcated
proximal tubular section 265 instead of one, each folded tubular
section 125 being joined to a distal tubular section 130. The
structure of each folded tubular section 125 of the bifurcated
intravascular folded tubular member 260 is the same as the
structure of the folded tubular section 125 of the straight
intravascular folded tubular member 95 shown in FIGS. 2A-2E. Each
folded tubular section 125 has a continuous tubular wall that is
folded back and forth upon itself to form a folded tubular section
inner wall 165, a folded tubular section center wall 160, and a
folded tubular section outer wall 155. In the folded tubular
section 125 a portion of the inner surface 135 is in apposition
with another portion of the inner surface 135. In the folded
tubular section 125 a portion of the outer surface 140 is in
apposition with another portion of the outer surface 140. Each
folded tubular section 125 has a proximal circumferential fold line
175 to a distal circumferential fold line 180 and has a nondeployed
folded tubular section length 185 extending between the proximal
175 and distal 180 fold lines. Each folded tubular section 125 has
a wall with an upstream end 187 and a downstream end 188. The wall
of the bifurcated proximal tubular section 265 is joined to folded
tubular section upstream end 187, and the distal tubular section
wall 190 is joined to the folded tubular section downstream end
188. The bifurcated proximal tubular section 265 has a bifurcated
nondeployed proximal tubular section length 285 and the distal
tubular section 130 has a nondeployed distal tubular section length
200. The nondeployed distal tubular section length 200 can have
significant length to accommodate a variety of vascular
applications with varying lengths of vascular injury. Alternately,
the nondeployed distal tubular section 130 can have negligible
length and the distal tubular section 130 can consist of the outlet
end 148. All reference numerals correspond to those elements
previously or otherwise described.
[0132] FIG. 4B shows the bifurcated intravascular folded tubular
member 260 in a fully deployed state or implanted state, being
deployed to both a larger radially deployed inlet end diameter 105,
a larger radially deployed outlet end diameter 110, and a longer
bifurcated deployed tubular member length 290. During full
deployment to a bifurcated deployed tubular member length 290, the
bifurcated proximal tubular section 265 extends in length to a
bifurcated deployed proximal tubular section length 295, the distal
tubular section 130 extends in length to a deployed distal tubular
section length 220, and the folded tubular section 125 reduces in
length to a deployed folded tubular section length 210. This
extension in length from a shorter bifurcated nondeployed tubular
member length 280 to a longer bifurcated deployed tubular member
length 290 is accomplished as the folded tubular section 125
unfolds an appropriate amount to achieve an appropriate bifurcated
deployed tubular member length 290 for the bifurcated intravascular
folded tubular member 260. During the unfolding process it is
possible for either the bifurcated nondeployed proximal tubular
section length 285 or the nondeployed distal tubular section length
200 to extend more than the other tubular section length extends in
forming the bifurcated deployed tubular member length 290.
[0133] The bifurcated intravascular folded tubular member 260 is
generally intended to be delivered to the site of a lesion such as
an aortic aneurysm in a nondeployed or insertion state as shown in
cross section in FIGS. 4C and 4D. FIG. 4C shows a cross sectional
view of the bifurcated intravascular folded tubular member 260 near
the inlet end 145 in a nondeployed state; FIG. 4D shows a cross
sectional view of the bifurcated intravascular folded tubular
member 260 near the outlet end 148 in a nondeployed state. A
guidewire 298 is shown extending through one distal tubular section
130 of FIG. 4D and through the center of the bifurcated proximal
tubular section 265 in FIG. 4C. The bifurcated intravascular folded
tubular member 260 can also be mounted on a balloon dilitation
catheter 300 (see FIG. 4E) and delivery system capable of expanding
the bifurcated intravascular folded tubular member 260 from a
nondeployed state or insertion state to a larger deployed diameter
237 representative of the radially deployed state of FIG. 4A or
fully deployed state of FIG. 4B. As an intravascular tubular member
85 of the present invention the straight intravascular folded
tubular member 95 and the bifurcated intravascular folded tubular
member 260 are intended to be delivered to the site of vascular
injury with a smaller nondeployed diameter 305 that can easily fit
within a small surgical access or percutaneous access in a blood
vessel either proximal or distal to the vascular injury. Once the
intravascular tubular member is delivered to the site of vessel
injury it will expand out to larger deployed diameter 237 that is
approximately equal to the diameter of the native vessel that is to
be repaired. In one embodiment the bifurcated intravascular folded
tubular member 260 can be held with a smaller nondeployed inlet end
diameter 230 and nondeployed outlet end diameter 235 by a delivery
sheath 225. For treatment of abdominal aortic aneurysm 5 the
delivery sheath 225 containing the bifurcated intravascular folded
tubular member 260 is generally introduced into one common femoral
artery 30 and advanced proximally through the native lumen 53 of
the common iliac artery 20 and abdominal aorta 10 to the proximal
aortic neck 90 generally located just distal to the renal arteries
45 & 50 (see FIGS. 1A and 1B). The bifurcated intravascular
folded tubular member 260 is released from the delivery sheath 225
such that the inlet end 145 is positioned distal to the renal
arteries 45 & 50 and the bifurcated intravascular folded
tubular member 260 expands to the radially deployed inlet end
diameter 105. This can be accomplished, for example, for a
bifurcated intravascular folded tubular member that is
self-expandable or has an attachment means attached to the inlet or
outlet ends that is self-expandable. The delivery sheath 225 is
removed delivering the bifurcated intravascular folded tubular
member 260 to the abdominal aorta 10 in a partially deployed state
as shown in FIG. 4A. Alternately, the present invention can be made
to expand from a nondeployed state of smaller nondeployed inlet end
diameter 230 or nondeployed outlet end diameter 235 to a deployed
state of larger radially deployed inlet end diameter 105 or
radially deployed outlet end diameter 110 using a mechanical
expansion device such as a balloon dilitation catheter 300. In this
case the bifurcated intravascular folded tubular member or the
attachment means which can be attached thereto can be
balloon-expandable. Each outlet end 148 of the two distal tubular
sections is positioned at the appropriate location within the
common iliac artery 20, external iliac artery 25, or common femoral
artery 30. This positioning causes each of the folded tubular
sections to unfold to provide the appropriate lengths for each of
the two deployed folded tubular section lengths 210. The bifurcated
intravascular folded tubular member 260 is then fully deployed and
extends from a region of the abdominal aorta proximal to the vessel
injury or aneurysm to two distal iliac or femoral arteries. The
inlet end 145 of the bifurcated intravascular folded tubular member
260 provides passage for blood flow from the abdominal aorta
proximal to the vessel injury into the blood flow passage 100 and
each outlet end 148 providing passage for blood flow to each of two
distal arteries located distal to the vessel injury. FIG. 4F shows
the bifurcated intravascular folded tubular member 260 in an
unfolded state with a bifurcated unfolded tubular member length 315
as it might appear prior to forming each folded tubular section 125
found in FIGS. 4A and 4B. All reference numerals correspond to
those elements previously or otherwise discussed.
[0134] An additional preferred embodiment of a bifurcated
intravascular folded tubular member 260 is shown in FIG. 5 with an
attachment anchor 245 or other attachment means 87 at the inlet end
145 and at each outlet end 148. The attachment means 87 can be any
barbed or non-barbed attachment means found in the prior art or
device that can be used to anchor the ends of an intravascular
tubular member. The attachment means 87 serves to hold the
bifurcated intravascular folded tubular member 260 firmly against
the vessel wall at its inlet end 145 and outlet end 148 to prevent
migration, and reduce leakage between the bifurcated intravascular
folded tubular member 260 and the native lumen 53 (see FIGS. 1A and
1B). The bifurcated intravascular folded tubular member 260 is not
required to have an attachment means. A separate stent such as
found in the prior art placed on the inner surface 135 at the inlet
end 145 and outlet end 148 of the bifurcated intravascular folded
tubular member 260 can be used to prevent migration and leakage. At
the inlet end 145 an attachment anchor 245 of the present invention
with barbs 250 similar to that shown in FIG. 3 can be attached.
This attachment anchor 245 will be described in detail later in
this disclosure. Securing fibers 255 or other securing means attach
the attachment anchor 245 to the inner surface 135 of the
bifurcated proximal tubular section 265 near the inlet end 145. The
attachment anchor 245 with barbs 250 can be short to allow it to be
placed more accurately near the renal arteries without extending
distally beyond the aortic neck into the aneurysmal space. The
attachment anchor 245 shown allows an increased number of barbs 250
to be positioned along the circumference of the attachment anchor
245. This increased number of barbs 250 allows the bifurcated
intravascular folded tubular member 260 to be anchored well to the
aortic wall to prevent leakage of blood, prevent migration, and may
also provide some additional support to prevent further dilation of
the abdominal aorta. An attachment anchor 245 without barbs 250 is
attached to the inner surface 135 of each distal tubular section
130 at each outlet end 148 using securing fibers 255. Each
attachment anchor 245 either with or without barbs 250 can be
constructed out of an elastic metal such as Nitinol, stainless
steel, or other metal or metal alloy that provides the attachment
anchor 245 with a self expanding characteristic. Alternately, the
attachment anchor 245 can be formed out of a metal such as
stainless steel, titanium, tantalum, platinum, or other metal or
metal alloy that undergoes plastic deformation to attain a deployed
attachment anchor diameter 320.
Unfolding of Folded Tubular Section
[0135] It can be desirable for the folded tubular section 125 to
unfold evenly or in a controlled manner without wrinkling as it
moves from a nondeployed folded tubular section length 185 to a
deployed folded tubular section length 210. Furthermore it is
desirable for the folded tubular section 125 (see FIG. 4B) to
remain at a constant deployed folded tubular section length 210
with the straight or bifurcated intravascular folded tubular member
95 & 260 in a fully deployed state. FIG. 6 shows the
nondeployed state of the folded tubular section 125 including its
junction to the straight proximal tubular section 120 and its
junction to the distal tubular section 130. This discussion applies
equally well for the folded tubular section 125 joined to the
bifurcated proximal tubular section 265 (see FIGS. 4A and 4B). As
shown in FIG. 6 a bonding agent 325 can be applied to the portion
of the outer surface 140 of the folded tubular section 125 that is
in apposition with another portion of the outer surface 140 of the
folded tubular section 125. The bonding agent 325 can be an
adhesive such as cyanoacrylate, epoxy, polyurethane, or other
adhesive that would allow the bonded region to peel at the proximal
circumferential fold line 175 preferential to the distal
circumferential fold line 180 and allow expansion of the straight
intravascular folded tubular member 95 from a straight nondeployed
tubular member length 115 to a straight deployed tubular member
length 205 as described earlier in FIGS. 2A and 2B. The adhesive
would resist wrinkling of the folded tubular section center wall
160 due to relative movement or slippage of the folded tubular
section center wall 160 with respect to the folded tubular section
inner wall 165 or folded tubular section outer wall 155. Placement
of the bonding agent 325 on the portions of the outer surface 140
of the folded tubular section 125 which are in apposition would not
significantly affect thrombosis of the straight intravascular
folded tubular member 95 or bifurcated intravascular folded tubular
member 260 (see FIGS. 4A and 4B) since the outer surface 140 is not
in contact with blood flow. Placement of the bonding agent 325 on
the outer surface 140 of the folded tubular section 125 that is in
apposition can allow the distal tubular section 130 to elongate
preferentially to, or with a greater length change than, the
straight proximal tubular section 120 or bifurcated proximal
tubular section 265 (see FIGS. 4A and 4B) for the case of the
bifurcated intravascular folded tubular member 260. A bonding agent
325 that would not create thrombosis could also be applied to the
portions of the inner surface 135 of the folded tubular section 125
that were in apposition. This would further reduce wrinkling of the
folded tubular section center wall 160 and allow the folded tubular
section 125 to unfold in a controlled manner, with unfolding
providing for more even extension of the straight proximal tubular
section 120 with respect to the distal tubular section 130.
[0136] The unfolding of the folded tubular section inner wall 165,
folded tubular section center wall 160, and folded tubular section
outer wall 155 (see FIGS. 2A and 4A) can be seen more clearly in
the schematic sectional drawings of FIGS. 7A-7E which show folded
tubular section walls 330 along with their junction to the straight
proximal tubular section wall 170 and the distal tubular section
wall 190. It is understood that this teaching of unfolding applies
equally well to each folded tubular section 125 found in the
bifurcated intravascular folded tubular member 260 of FIGS. 4A and
4B. FIG. 7A shows the folded tubular section 125 having the folded
tubular section walls 330 with the outer surface 140 of the folded
tubular section inner wall 165 in apposition with the outer surface
140 of the folded tubular section center wall 160. The inner
surface 135 of the folded tubular section center wall 160 is in
apposition with the inner surface 135 of the folded tubular section
outer wall 155. Markers in the form of a circle 335, square 340,
point-up triangle 345 and point-down triangle 350, and rectangle
355 mark positions on the folded tubular section 125 of FIG. 7A
with a nondeployed folded tubular section length 185 for reference
purposes. In FIG. 7B the deployed folded tubular section length 210
has been reduced as the folded tubular section center wall 160 from
the circle 335 to the rectangle 355 has unfolded to become the
folded tubular section inner wall 165. The straight deployed
proximal tubular section length 215 has lengthened from the
straight nondeployed proximal tubular section length 150 more than
the deployed distal tubular section length 220 has increased from
the nondeployed distal tubular section length 200. This form of
unfolding can generally occur when bonding agent 325 is placed only
on portions of the inside surface of the folded tubular section 125
in apposition with another portion of inside surface. In FIG. 7C
the deployed folded tubular section length 210 has been reduced
from FIG. 7A as the folded tubular section center wall 160 from the
rectangle 355 to the square 340 has unfolded to become the folded
tubular section outer wall 155. The deployed distal tubular section
length 220 has lengthened more than the straight deployed proximal
tubular section length 215 has lengthened. This form of unfolding
can be generated by placement of a bonding agent 325 on portions or
the outer surface 140 of the folded tubular section 125 in
apposition with another portion of outside surface as described in
FIG. 6. In FIG. 7D the deployed folded tubular section length 210
has been reduced from the nondeployed folded tubular section length
185 shown in FIG. 7A as a portion of the folded tubular section
center wall 160 has unfolded to become a portion of both the folded
tubular section inner wall 165 and the folded tubular section outer
wall 155. The straight deployed proximal tubular section length 215
and the deployed distal tubular section length 220 have both
increased. This form of unfolding can occur if the folded tubular
section inner wall 165 and folded tubular section outer wall 155
unfold evenly. Placing an effectively similar bonding agent 325 on
both the inner surface 135 and outer surface 140 can result in this
even unfolding pattern. Similar results can occur with no bonding
agent placed on the folded tubular section 125. In FIG. 7E the
deployed folded wall section length has been reduced from FIG. 7A.
The folded tubular section center wall 160 has not unfolded but has
rather wrinkled to allow the straight deployed proximal tubular
section length 215 and the deployed distal tubular section length
220 to increase. The use of a bonding agent 325 as explained in
FIG. 6 can enhance the ability of the straight intravascular folded
tubular member 95 and bifurcated intravascular folded tubular
member 260 of the present invention to unfold in a manner similar
to the methods described in FIGS. 7A-7D and not wrinkle in an
uncontrolled manner as shown in FIG. 7E.
[0137] FIG. 8 shows a folded tubular section 125 with holding pins
360 extending through the folded tubular section inner wall 165,
folded tubular section center wall 160, and folded tubular section
outer wall 155. Following full deployment of the straight
intravascular folded tubular member 95 or bifurcated intravascular
folded tubular member 260 such holding pins 360 or other form of
holding means can be placed to ensure that further elongation of
the intravascular tubular member cannot occur. The holding pins 360
can be the same as the barbs 250 located on the attachment anchor
245 of the present invention.
Attachment Anchor
[0138] FIG. 9A is an isometric view of an embodiment of the
attachment anchor 245 of the present invention without barbs in a
nondeployed state. FIGS. 9A-9C will be discussed collectively. This
attachment anchor 245 is similar to the attachment anchor shown in
FIG. 5 except that the barbs 250 are not present. The attachment
anchor 245 of the present invention is comprised entirely out of
nodes 365 and struts 370 arranged in a ring structure. The
attachment anchor 245 of the present embodiment is comprised of a
series of nodes 365 and struts 370 arranged in a generally
cylindrical shape. The axially oriented struts 370 are separated by
interstrut openings 375. Each of the nodes 365 include at least one
hinge 380 and have an intranodal opening 385 that connects with one
of the interstrut openings 375. This attachment anchor 245 can be
machined from a metal cylinder using machining techniques including
mechanical machining, laser machining, chemical machining,
electrochemical etching, electric discharge machining, and other
machining methods. The metal used in the formation of the
attachment anchor 245 can include stainless steel, Nitinol,
tantalum, titanium, platinum, gold, or other metals or metal
alloys. Nitinol, some stainless steel compositions, or other metals
with elastic properties are suited to an attachment anchor 245 that
is self-expandable; other stainless steel compositions, titanium,
and other metals or metal alloys with plastic deformation
properties can be suited to an attachment anchor 245 that is
balloon-expandable. The metal can be chosen to provide a high yield
strength or have a high elastic modulus or Young's modulus that can
provide the attachment anchor 245 with a high expansion force while
maintaining a lower profile and a more supple feel in a crushing
deformation. A crushing deformation tends to deform the generally
cylindrically shaped attachment anchor 245 into an oval shape. The
design of the nodes 365 and the struts 370 can be chosen to provide
appropriate outward expansion forces by the attachment anchor 245
for a particular application. Typically a larger diameter and
thicker walled blood vessel would require an attachment anchor 245
with greater expansion forces outward against the blood vessel wall
than a smaller diameter, thinner walled blood vessel. The
attachment anchor 245 must provide adequate outward expansion force
to hold the intravascular tubular member of the present invention
outward against the blood vessel wall without leakage, it must
resist any compression forces offered by the blood vessel, and it
must prevent migration of the intravascular tubular member. The
attachment anchor 245 is a radially expandable vascular implant
that can be a self-expandable attachment anchor 245 or a
balloon-expandable attachment anchor 245. The design of the node
365 can be altered to provide for a completely elastic deformation
of the metal in the hinge 380 or to provide for plastic deformation
of the metal in the hinge 380. The intranodal openings 385 provide
sites for attachment of securing fibers 255 (see FIGS. 3 and 5) to
the attachment anchor 245 in order to hold the attachment anchor
245 to a straight intravascular folded tubular member 95, or to a
bifurcated intravascular folded tubular member 260 as described in
FIGS. 3 and 5, or to any other tubular member or tubular means that
is used as an intravascular graft or intravascular tubular member.
The attachment anchor 245 of the present invention can be used with
other prior art stent-graft devices to anchor such devices to a
blood vessel. In a nondeployed state, the struts 370 are adjacent
and parallel to each other and in direct apposition to each other
to provide the closest position of struts 370 with respect to each
other. This provides the attachment anchor 245 with an ability to
attain the largest expansion ratio of attachment anchor diameters
from a deployed state to a nondeployed state. The attachment anchor
has a hinge width radius of curvature 386 (FIG. 9B) which describes
the radius of curvature with the direction of the radius of
curvature aligned with the direction of the hinge width 420 (FIG.
9C). The attachment anchor 245 has a nondeployed attachment anchor
diameter 387.
[0139] FIG. 9A shows an isometric view of the attachment anchor 245
in a nondeployed state with a smaller nondeployed diameter 387 or
insertion diameter and FIG. 9B shows the attachment anchor 245 in a
deployed state with a larger deployed attachment anchor diameter
380. The strut length 390 remains constant from the nondeployed or
insertion state to the deployed or implanted state. A deployed
attachment anchor length 395 in an axial direction 398 is shorter
than the nondeployed attachment anchor length 400 but the amount of
length change is minimal due in part to the increased number of
deformation sites or nodes 365 found in the present attachment
anchor 245 in comparison to other prior art attachment devices.
Additionally, the greater number of deformation sites or nodes
allows each deformation site to undergo a smaller deformation with
less attachment anchor length change. The interstrut openings 375
between the struts 370 in a circumferential direction 403 in a
nondeployed state can be negligible and the struts 370 can be in
direct contact with each other. The generally cylindrical shape of
the attachment anchor has a generally cylindrical uniformly curved
attachment anchor surface 404 formed by the struts 370 and nodes
365. In addition, the attachment anchor can be deployed to a small
deployment angle 405 of less than 60 degrees which further reduces
the amount of attachment anchor length change in going from a
nondeployed state to a deployed state. The deployment of the
attachment anchor 245 to a smaller deployed angle 405 in comparison
to other prior art attachment devices can be accomplished due to
the greater number of nodes 365 found on the present attachment
anchor 245. Alternately, the attachment anchor 245 of the present
invention can be deployed to a larger deployment angle 405 than
other prior art attachment means formed with round wires due to the
greater force that can be generated by the hinge 380 of the present
invention in comparison to a round wire. This greater force can be
generated due to the hinge design and due to the higher modulus
material that can be used for the hinge. The larger deployment
angle 405 can provide the present attachment anchor 245 with a
greater expansion ratio of deployed attachment anchor diameter 320
to nondeployed attachment anchor diameter 387. The attachment
anchor 245 is deployed from a smaller insertion diameter or
nondeployed attachment anchor diameter 387 in its nondeployed or
insertion state to a larger deployed attachment anchor diameter 320
or insertion diameter in its deployed or implanted diameter. The
ratio of deployed attachment anchor diameter 320 to nondeployed
attachment anchor diameter 387 is maximized by positioning the
struts 370 parallel and in apposition to each other in the
nondeployed state.
[0140] FIG. 9C is an enlarged isometric view of a portion of the
attachment anchor 245 shown in FIG. 9A. Each of the nodes 365
comprises the hinge 380 and two transition regions 410. The hinge
380 has a hinge length 415, a hinge width 420, and a hinge radial
dimension 425. The strut 370 has a strut width 430, a strut radial
dimension 435, and a strut length 390 as shown in FIG. 9A. The
hinge 380 has a greater hinge radial dimension 425 than the strut
radial dimension 435 and the hinge 380 has a smaller hinge width
420 than the strut width 430. Each of the transition regions 410
extends from the hinge 380 to the strut 370. It has a transition
width 440 that varies from the smaller hinge width 420 to the
larger strut width 430 and a transition radial dimension 445 that
varies from the larger hinge radial dimension 425 to the smaller
strut radial dimension 435. The transition regions 410 provides a
smooth uniform transition of metal strength and conformation from
each hinge 380 to each of the struts 370. The struts 370 have a
strut cross sectional area 447 that can be different from and
varied independently from a hinge cross sectional area 448. As
shown in FIGS. 9A and 9B the attachment anchor 245 has a
nondeployed attachment anchor perimeter 449 and a deployed
attachment anchor perimeter 451. The transition regions 410 have an
abrupt transition region length 452 that is as short as possible
without causing a discontinuity in cross sectional area in order to
maximize the hinge length 415 and strut length 390. The cross
sectional areas of the transition regions are maintained to be
larger than either the strut cross sectional area 447 or the hinge
cross sectional area 448.
[0141] An embodiment of the attachment anchor 245 is a
self-expandable vascular implant that can be used with the straight
intravascular folded tubular member 95, bifurcated intravascular
folded tubular member 260 of the present invention, or with any
other intravascular tubular means that is used for intravascular
repair of blood vessels. The hinge length 415 can be long,
extending approximately from one of the transition regions 410 to
another as shown in FIG. 9C and having a hinge length 415 equal to
or greater than approximately twice the strut width 430. For a
self-expandable attachment anchor 245 with a long hinge length 415
several advantages are obtained over prior art attachment devices
such as those formed from zig zag shaped wire. The long hinge
length 415 provides a smaller drop-off of the expansion elastic
force exerted outward against the vessel wall by the attachment
anchor 245 as the attachment anchor 245 extends from a nondeployed
state to a deployed state with an elastic deformation. This smaller
drop-off of outward expansion force provides a similar outward
force over a variety of diameters for which the same attachment
anchor can be used. The attachment anchor 245 of the present
invention can therefore exert a greater outward force in a fully
deployed state as shown in FIG. 9C than one with a shorter hinge
length 415 and similar hinge width 420 and hinge radial dimension
425 and the same outward expansion force in a nondeployed state. In
addition, the hinge 380 of the present attachment anchor 245 is
responsible for generating the outward force, and the hinge 380 is
positioned with significant circumferential direction 403. The
strut 370 does not significantly contribute to generating the
outward expansion force generated by the attachment anchor 245. The
deployed or nondeployed attachment anchor length 395 & 400, in
substantially an axial direction 398, can be smaller than other
prior art or zig zag wire type attachment devices that provide
similar outward expansion forces. This allows the attachment anchor
245 to form a more focused line attachment to the vessel wall
consisting of a ring of small axial length in the axial direction
398 for contact between the attachment anchor 245 and the vessel
wall or a focused attachment between the attachment anchor 245 and
the vascular tubular member 85 that resides between the attachment
anchor 245 and the blood vessel wall. Prior art zig zag wire
attachment devices have a portion of the wire bent in a hair-pin
turn and another portion that is not bent as significantly forming
a wire strut. Prior art zig zag wire attachment devices generate a
majority of their elastic outward force from the portion that is
significantly bent. These prior art devices rely in part on the
bending of the wire that is not significantly bent to generate the
elastic force that is exerted outward against the vessel wall.
These bending wires from zig zag wire attachment devices extend in
significantly an axial direction 398 with a greater axial length
than the struts of an embodiment of the present invention. The
attachment anchor 245 of the present invention can be constructed
with a smaller deployed attachment anchor length 395 than prior art
devices and can be positioned closer to the renal vessels of the
aorta with less chance of distal migration.
[0142] Alternately, the attachment anchor 245 of the present
invention can be used with a mechanical expanding means such as the
dilitation balloon of a balloon expansion catheter. The attachment
anchor 245 can be forced to expand due to the dilitation balloon
causing the metal located in the hinge 380 to deform plastically
and hold the intravascular tubular member of the present invention
or other intravascular stent-graft out against the aortic wall. The
struts 370 for the balloon-expandable attachment anchor 245 do not
contribute significantly to the outward expansion force generated
by the hinge 380 of the attachment anchor 245. The struts 370
transfer the outward expansion force generated by the hinge 380
from one node to another to the vessel wall to hold the vessel wall
outward, provide a seal, and help prevent migration of the
intravascular tubular member. The hinge 380 of the attachment
anchor 245 can be adjusted in hinge length 415, hinge width 420, or
in hinge radial dimension 425 to provide the necessary outward
forces to hold the intravascular tubular member 85 of the present
invention or other prior art intravascular stent-graft outwards
against the aorta.
[0143] The attachment anchor 245 of this embodiment, whether a
balloon-expandable attachment anchor or a self-expandable
attachment anchor, has a single ring structure formed of nodes 356
and struts 370 with the struts 370 folded back and forth adjacent
to each other in the nondeployed state. The hinge length 415, width
420, and radial dimension 425 provide an expansion deformation in
the uniformly curved attachment anchor surface 404 that produces an
outward expansion force exerted against the vessel wall or the
intravascular tubular member wall 143 in its expanded state. The
struts 370 transfer the forces generated by the hinges 380 to the
vessel or intravascular tubular member wall 143. The struts 370 do
not deform within the uniformly curved attachment anchor surface
404 due to the larger strut width 430 in comparison to the hinge
width 420. If the attachment anchor 245 is subjected to a crush
deformation such that it forms an oval attachment anchor surface
453, the struts 370 will bend in a radial direction due to the
relatively small strut radial dimension 435 with an elastic
deformation. The strut length, width, and radial dimension all
provide the strut with an ability to flex elastically during the
crush deformation. The hinge will not deform in the radial
direction upon exposure to a crush deformation due to the large
hinge radial dimension 425 in comparison to the strut radial
dimension 435. A longer strut length 390 along with a fewer number
of nodes will allow the attachment anchor 245 to have a greater
percentage of the attachment anchor associated with the struts 370
in comparison to the hinges 380 and hence provide the attachment
anchor with a greater flexibility in bending due to a crush
deformation.
[0144] Other prior art attachment means including those with zig
zag designs have a long axial length to reduce the number of zig
zags that are used around their circumference and hence reduce the
amount of volume occupied by the attachment means per axial length
times the deployed diameter. Most zig zag designs in a nondeployed
state consist of a series of hair pin turns connected by straight
wire segments that are generally not parallel to each other. The
hair pin turns have a radius of curvature that limits the number of
hair pin turns that can be used or that will fit along a
circumference of an attachment means. The attachment anchor 245 of
the present invention has struts 370 that are generally parallel to
each other and can be in direct apposition or contact with each
other in a nondeployed state (see FIG. 9A) and each hinge 380 is
machined such that it is smaller in hinge length 415 than a
curvature diameter for the hair pin turn for the attachment means
of the prior art. The hinge length 415 can have a length of
approximately twice the strut width 430. The hinge conformation
allows it to generate a larger outward force than that generated by
prior art wire hair-pin turns formed with a similar curvature
diameter. Therefore, many more nodes 365 of the present invention
each with a hinge 380 can be placed around the circumference of the
nondeployed attachment anchor 245. This greater number of nodes 365
and accompanying struts 370 allows each of the struts 370 to be
shorter in length than other prior art attachment means in order to
achieve a specific expansion ratio of deployed diameter 237 to
nondeployed diameter 238 and a specific outward force. The presence
of the hinge 380 allows the outward expansion force provided by the
attachment anchor 245 within the uniformly curved attachment anchor
surface 404 to be controlled by setting the hinge radial dimension
425, hinge length 415, and hinge width 420. The expansion
deformation occurs with the hinges deforming within the uniformly
curved attachment anchor surface 404. A higher strength metal can
be used with the present hinge 380 allowing a greater outward
expansion force to be exerted with a thinner hinge width 420 or
with less metal volume per nondeployed hinge length 415 being used
in the attachment anchor 245. This provides a smaller attachment
anchor diameter in the nondeployed state which can fit into a
smaller diameter sheath. This outward expansion force is controlled
independently from the crush force which is controlled by the strut
dimensions.
[0145] A thin strut radial dimension 435 can provide the attachment
anchor 245 with a flexibility to form an oval attachment anchor
surface 453 when exposed to a crush deformation by allowing the
thin struts 370 to bend in the radial direction in forming an oval
shape as shown in FIG. 9D. The oval attachment anchor surface 453
of FIG. 9D that is found when the attachment anchor 245 is exposed
to crush deformation is not found in the uniformly curved
attachment anchor surface 404 which is maintained in a cylindrical
shape during normal expansion deformation of the attachment anchor
245. The result is that the attachment anchor 245 can fit into a
small diameter delivery sheath 225 in its nondeployed or
nonexpanded state yet has high expansion force and is flexible in
crush deformation. This combination of properties is not possible
with the round wire zig zag or other attachment means described in
the prior art in which the expansion force and crush force of the
attachment device are tied together. Alternately, it is further
understood that the strut radial dimension 435 can be formed large
enough such that the struts 370 will not flex easily if exposed to
a crush deformation. In this case the attachment anchor will retain
a substantially cylindrical shape with a uniformly curved
attachment anchor surface 404 and will be resistant to forming an
oval shape characteristic of crush deformation. The strut
deformation due to crush is always an elastic deformation and is
more easily deformed than the hinge in a radial direction.
[0146] The short attachment anchor length with a greater number of
nodes 365, and struts 370 allows the attachment anchor 245 to be
placed such that it is more firmly anchored into healthy blood
vessel with a more focal line of attachment to the vessel. For the
example of the abdominal aortic aneurysm 5, the attachment anchor
245 can be placed closer to the aortic neck and nearest to the
renal arteries 45 & 50 in order to get a more firm anchoring
into the aortic wall 70 and not into the thrombus 60 that lines the
native lumen 53 for most of the lumen of the abdominal aorta 10
(see FIGS. 1A and 1B). The shorter length also provides an
advantage for forming a better seal of the intravascular tubular
member with the vessel wall. The shorter length and increased
number of nodes 365 further allows more barbs 250 to be placed
along the circumference of the attachment anchor 245. This increase
in number of barbs 250 (see FIGS. 3 and 5) provides better
attachment at an increased number of sites. The result is an
increased ability to form a leak free seal between the native blood
vessel and the inlet end 145 or outlet end 148 of any intravascular
tubular member or other stent-graft device. Furthermore, the
attachment anchor 245 with short length and with the increase
number of barbs 250 is more likely to provide an intravascular
tubular member or other stent-graft device of any type a greater
resistance to distal migration.
[0147] For a self-expandable attachment anchor 245 an increase in
hinge width 420 or hinge radial dimension 425 will increase the
amount of outward force provided by the attachment anchor 245 for
the same deployment angle 405 or amount of expansion deformation.
Increasing the hinge length 415 will result in a smaller drop-off
in outward force provided by the attachment anchor 245 as it
expands from a nondeployed state to a deployed state. Therefore, by
changing the dimensions of the hinge 380, the outward force
delivery characteristics of the attachment anchor 245 can be
adjusted to provide the desired outward elastic expansion force.
The strut width 430 and strut radial dimension 435 can be adjusted
to provide struts 370 that will remain elastic during the expansion
of the attachment anchor 245 or during crush deformation with
greater flexibility due to bending to an arc with the radius of
curvature in the direction of the smaller strut radial dimension
435 and more rigidity in the direction of bending of the larger
strut width 430. The small strut radial dimension 435 allows the
attachment anchor 245 to be soft and pliable in a crushing type of
deformation while maintaining a large expansion force in the
circumferential direction 403 needed to hold the blood vessel
outward with appropriate force and without leakage between the
intravascular tubular member 85 and the vessel wall.
[0148] For a balloon-expandable attachment anchor 245 the
dimensions of the hinge 380 can affect its ability to yield under
the expansion force of the dilitation balloon and its ability not
to yield under the forces applied to it by the aorta. Increasing
the hinge width 420 and hinge radial dimension 425 will increase
the amount of yield force that is required to expand the attachment
anchor 245 from a nondeployed state to a deployed state; it will
also increase the amount of yield force that must be exceeded for
the aorta to collapse the attachment anchor 245. Increasing the
hinge width will reduce the amount of deployment angle 405 that is
required before plastic deformation will occur and the hinge 380
will no longer return to its original position or equilibrium
position with all external forces removed. Reducing the hinge
length 415 will cause the metal in the hinge 380 to deform a
greater extent during the expansion from the nondeployed state to
the deployed state. The hinge 380 with a smaller hinge length 415
will have a greater tendency to undergo a plastic deformation for a
smaller expansion deformation. The struts 370 for the
balloon-expandable attachment anchor 245 also remain elastic during
the expansion deformation as well as during crush deformation.
[0149] An increase in strut length 390 also increases the
flexibility of the attachment anchor 245 in undergoing a crush
deformation to an oval shape. Since the struts 370 are smaller in
the radial dimension 435 than the hinge 425 or the transition
region 445, the struts bend more easily in the radial direction.
Increasing the length 390 of the struts 370 provides a greater
percentage of the attachment anchor 245 that is associated with the
struts 370 in comparison with hinges 380 or transition regions 410
and therefore provides a greater flexibility in the radial
direction during crush deformation.
[0150] An alternate embodiment for the attachment anchor 245 is
shown in FIGS. 10A and 10B. FIG. 10A shows the attachment anchor
245 in a nondeployed state with the attachment anchor 245 not
expanded. FIG. 10B shows the attachment anchor 245 after it has
been expanded to a deployed state. The main difference between this
embodiment and the one presented in FIG. 9A-9C is the shape of the
nodes 365 and the presence of two hinges 455 on each of the nodes
365. The nodes 365 and struts 370 are aligned in series in the same
way as the embodiment shown in FIGS. 9A-9C. Each node 365 of this
embodiment is joined to two struts 370 and each strut 370 is joined
to two nodes 365 in a manner similar to that shown for the
embodiment of FIGS. 9A-9C. All reference numerals correspond to
those elements previously or otherwise described. A detailed
isometric view of one of the nodes 365 plus a portion of two struts
370 is shown in FIG. 10C. Each of the nodes 365 is comprised of a
hub 457, two hinges 455, and two transition regions 410. The hub
457 provides a less flexible portion of each node 365 to which the
two more flexible hinges 455 can be joined. Deformation is
substantially less or absent from the hub 457. The transition
regions 410 are similar in design and function to the transition
regions 410 described in FIG. 9C. The two hinges 455 perform a
similar function as the single hinge 380 described in FIG. 9C. Each
of the hinges 455 has a smaller hinge width 420 and a longer hinge
radial dimension 425 in comparison to the larger strut width 430
and shorter strut radial dimension 435, respectively. The length of
the transition region 410 is abrupt or short to conserve length
that can be used as length for the struts 370 or the hinge 380.
[0151] For a self-expandable attachment anchor 245 each of the
hinges 455 is designed to deform elastically during the expansion
of the attachment anchor 245 from a nondeployed state to a deployed
state. A metal of very high yield strength and high elastic modulus
can be used for the attachment anchor 245 of the present invention.
A higher strength metal provides the attachment anchor 245 of the
present invention with an ability to have all components or
elements have a smaller radial dimension than other prior art
attachment devices. Increasing the hinge radial dimension 425 and
the hinge width 420 will provide an increase in the outward elastic
expansion force provided by the attachment anchor 245 in holding
the intravascular tubular member 85 of the present invention or
other intravascular stent-graft against the aorta. Reducing the
hinge length 415 will provide a larger outward force of the
attachment anchor 245 against the vessel wall in the deployed state
with a specific deployment angle 405 and provided that the hinge
radial dimension 425 and hinge width 420 remain constant for
comparison purposes. The hinge length 415 defines the region of the
nodes 365 wherein the majority of the expansion deformation occurs.
The hinge length 415 includes the region of each node 365 having a
smaller hinge width 420 than the strut width 430 and that remains
approximately constant in strut width 430 for a distance. The hinge
length 415 can include a region of a minimum hinge width 420. The
hinge length 415 can be long such as the case shown in FIG. 9C or
it can be very short as the case shown in FIG. 10C. With two hinges
455 associated with each of the nodes 365 it is possible to provide
each of the hinges 455 of each of the nodes 365 with different
dimensions and different expansion characteristics. The hub 457 can
provide a site for forming a contiguous junction to a barb 250. The
two hinges 455 shown in FIG. 10C can be easier to machine than a
single hinge 380 as shown in FIG. 9C.
[0152] For a balloon-expandable attachment anchor 245 an increase
in the hinge radial dimension 425 will cause an increase in the
yield force needed by a dilitation balloon to cause the attachment
anchor 245 to expand and will increase the yield force necessary to
cause collapse of the attachment anchor 245 due to compressive
forces applied by the abdominal aorta or other treated artery on
the deployed attachment anchor 245. An increase in the hinge width
420 will cause the expansion deformation from a nondeployed state
to a deployed state to cause more plastic deformation of the metal
hinges 455 for a specific deployment angle 405 and will require a
larger expansion deformation force. Increasing the hinge length 415
will reduce the amount of plastic deformation and reduce the rate
of change in force for a particular expansion deformation or
deployment angle 405. Adjusting the hinge length 415, hinge width
420, and hinge radial dimension 425 allows the balloon-expandable
attachment anchor 245 to be specifically designed to provide
appropriate yield forces for a specific vascular application. This
is not able to be accomplished with the wire zig zag or other
attachment devices described by the prior art.
Stress Versus Strain
[0153] The stress versus strain relationship for a metal bar or
beam such as a strut 370 or a hinge 380 & 455 can in general be
estimated by Hooke's law which states that stress applied to the
metal bar is equal to an elastic modulus times the strain or
deformation to which the bar will deform. This elastic modulus or
Young's modulus is a material property characteristic of the
particular metal being used for the bar. The deformation can be a
bending deformation that is characteristic of the expansion
deformation encountered by the strut 370 or the hinge 380 &
455. A bar in an unstressed state that is exposed to an applied
stress below its elastic limit or yield stress will undergo an
elastic flexure or elastic deformation which is reversible and the
bar will return to its unstressed state upon removal of the applied
stress. If the bar is exposed to an applied stress that is larger
than its yield stress or if it is deformed to an inelastic flexure
that is greater than its elastic limit or proportional limit, or if
it is deformed beyond its yield point, plastic deformation will
occur and the bar will not return to its original unstressed state
with the original conformation or shape of the bar. The bar will
generally return part way back to its initial unstressed state due
to the elastic portion of the deformation.
[0154] Exposing a bar to a torque or moment can result in bending
the bar from a straight shape to a bent conformation with a radius
of curvature. The relationship between the applied moment and the
radius of curvature can be estimated by the equation that states
that moment is equal to Young's modulus times moment of inertia
divided by radius of curvature. The moment of inertia is different
for different cross sectional shapes of the bar that is being bent.
For a bar having a circular cross section and having a diameter,
the moment of inertia is given by Pi times the diameter to the
fourth power divided by 64. For a rectangular bar cross section
with one side of magnitude B and another side of magnitude H, where
B is the magnitude of the side in the radial direction of the
radius of curvature and H is the magnitude of the side
perpendicular to B, the moment of inertia is given by B to the
third power times H divided by 12. Similarly, the bar can be bent
from one radius of curvature to a second radius of curvature with a
similar type of analysis as described above by examining a change
in radius of curvature that is comparable to that of starting from
a flat surface as just described.
[0155] The hinge cross sectional area 448 is equal to the
multiplication product of the hinge width 420 and the hinge radial
dimension 425. Each hinge 380 & 455 has a large hinge radial
dimension 425 that does not allow for significant bending
deformation along a radius of curvature with a radius aligned along
the hinge radial dimension. Bending deformation for each hinge 380
& 455 occurs to form a radius of curvature with the radius
aligned with the hinge width 420, and this radius of curvature is
referred to as the hinge width radius of curvature 386. The hinge
can undergo an expansion deformation with bending occurring in the
uniformly curved attachment anchor surface 404. The moment of
inertia for the hinge 380 & 455 can be estimated by using the
hinge width 420 to correspond with the magnitude B and the hinge
radial dimension 425 to correspond with the magnitude H. The strut
cross sectional area 447 is equal to the multiplication product of
the strut width 430 and the strut radial dimension 435. The moment
of inertia for each of the struts 370 can be estimated using the
strut radial dimension 435 to correspond with the magnitude B and
the strut width 430 to correspond with the magnitude H. In the
attachment anchor 245 of the present invention the hinge cross
sectional area 448 can be varied independently of the strut cross
sectional area 447 to provide the attachment anchor 245 with a
variety of expansion force characteristics and other properties.
For example, the hinge width 420 and hinge radial dimension 425 can
be equal to the diameter of a round wire and produce a moment that
is 1.67 times larger than the round wire based on the equation for
moment stated earlier. Thus for a similar magnitude of hinge width
in comparison to the diameter of a round wire, the attachment
anchor 245 in a nondeployed state can provide a greater outward
extension force by the hinge 380 & 455 to the struts 370 than a
circular cross sectional or round wire. The hinge radial dimension
425 can also be increased in magnitude to provide an even greater
moment of inertia to the hinge 380 & 455 such that even larger
moment is generated to produce larger extensional forces by the
attachment anchor 245. Increasing the hinge radial dimension 425
such that it is significantly larger than the hinge width 420 will
also have a profound effect on increasing the moment of inertia for
bending to a radius of curvature with the radius in the radial
direction. Hence the hinges 380 will not allow bending to occur in
the radial direction such as found in the struts 370 in forming an
oval shape during crush deformation.
[0156] As another embodiment for the design of the attachment
anchor 245, the hinge radial dimension 425 can be formed such that
it is approximately equal to the diameter of a prior art zig zag
wire that is used as an attachment means and the hinge width 420
can be smaller that the diameter of the zig zag wire. In this
embodiment the hinge 380 & 455 would undergo a smaller amount
of localized deformation associated with a bend to a specific
radius of curvature than the zig zag wire. The attachment anchor
245 could be formed out of a metal with a higher elastic modulus
than the prior art zig zag wire attachment means without undergoing
plastic deformation. The hinge 380 & 455 of the present
attachment anchor 245 can thus produce an equal or greater moment
than a round wire with a diameter larger than the hinge width 420
and remain elastic. This embodiment is particularly useful for a
self expanding attachment anchor 245.
[0157] For a balloon-expandable attachment anchor 245 the hinge
length 415 can be shortened such that the bending deformation of
the hinge 380 & 455 associated with expansion from the
nondeployed state to the deployed state exceeds the yield point of
the metal used to form the attachment anchor 245. For a bending
deformation of the hinge 380 & 455 from one hinge width radius
of curvature 386 to another hinge width radius of curvature 386, an
increase in the hinge width 420 will also serve to increase the
amount of hinge 380 & 455 material exposed to deformation
beyond the yield point of the metal. Hence both hinge length 415
and hinge width 420 can be adjusted to provide inelastic flexure of
the metal and plastic deformation. The hinge radial dimension 425
can be further adjusted to control the amount of force that is
required to expand the attachment anchor 245 to a particular amount
of deformation during deployment of the attachment anchor 245 and
to control the amount of force exerted by the attachment anchor 245
against the vessel wall in its deployed attachment anchor diameter
320.
[0158] The strut cross sectional area 447 can be different than the
hinge cross sectional area 448 and can be varied independently from
it. The strut width 430 is designed to be large enough such that
during expansion of the attachment anchor 245 the struts 370 do not
bend or flex significantly within the uniformly curved attachment
anchor surface 404 of the attachment anchor 245 with a radius of
curvature in a radial direction aligned with the strut width 430.
The hinge 380 & 455 can therefore transfer its moment to the
strut 370 which then exerts an outward force upon the vessel wall
to hold it outwards. Since the strut width 430 and strut radial
dimension 435 provide a rectangular cross sectional shape for the
strut 370 the strut width 430 can be smaller than the diameter of a
round wire and provide a greater moment in resisting bending
deformation to a radius of curvature with a radius in the direction
of the strut width 430. The struts 370 will not bend in within the
uniformly curved attachment anchor surface 404 such as in the
direction of their strut width 430.
[0159] The strut radial dimension 435 is formed to be thinner than
the hinge radial dimension 425 such that it can flex to form a
radius of curvature with a radius aligned with the strut radial
dimension 435; this bending deformation is similar to a crush
deformation that would cause the attachment anchor 245 to form an
oval attachment anchor surface 453 rather than the cylindrical
uniformly curved attachment anchor surface 404 that it normally
has. The struts 370 would remain elastic due to its thin wall, due
to a choice of metal such that the struts 370 do not exceed the
elastic limit of the metal, and due to a longer strut length that
distributes the bending along a longer length. The metal chosen for
forming the attachment anchor 245 could be chosen from a high
modulus material and still remain flexible to allow this bending
deformation to form an oval shape due to the thin radial dimension.
The prior art attachment means formed of a round wire or other
prior art structures of high modulus could not provide a
combination of a large outward extension force and a low or soft
crushing force since the properties of the round wire or other
prior art structures affect both the extension force and the crush
force. With this embodiment of the present invention, an attachment
anchor 245 could be formed entirely out of a high modulus metal
with the hinge 380 & 455 providing a large moment for expansion
deformation in the uniformly curved attachment anchor surface 404
and the strut 370 allowing the attachment anchor 245 to be bent to
an oval shape to accommodate variations in the shape of the aorta
or other blood vessel. The hinge 380 & 455 does not allow
bending in the radial direction due to crush deformation forces and
the strut 370 does not bend in the uniformly curved attachment
anchor surface 404.
[0160] The struts 370 can be increased in their radial dimension
435 to provide additional resistance to bending in crush
deformation. The strut radial dimension is still maintained smaller
than the hinge radial dimension 425 and smaller than the strut
width 430. The strut radial dimension 435 is not as large as the
hinge radial dimension 425 such that the strut always flexes
preferentially to the hinge in a crush deformation and the strut
370 is designed to flex elastically. The strut cross sectional area
447 has been altered independently of the hinge cross sectional
area 448. An increase in strut radial dimension 435 will provide
the strut 370 with a resistance to additional bending to a radius
of curvature with a radius aligned with the direction of the strut
radial dimension 435. This embodiment of the attachment anchor 245
will be resistant to crush deformation that would cause the
attachment anchor 245 to form an oval shape. The strut radial
dimension 435 is still less than the hinge radial dimension 425 and
the strut remains elastic when exposed to crush deformation.
[0161] The strut length 390 for the attachment anchor 245 of the
present invention can be small and thereby require a greater number
of struts 370 with smaller strut length 390 in order to extend and
provide contact with the vessel wall with an adequate outward
expansion force. The increased number of struts 370 and shorter
strut length 390 provides a more focused line of attachment of the
attachment anchor 245 to the blood vessel wall. In the case of
abdominal aortic aneurysm repair, the attachment anchor 245 can be
placed closer to the renal arteries with a better attachment to the
vessel wall proximal to the thrombus lining. In an expanded state
of the attachment anchor 245, the moment exerted by each hinge 380
& 455 is transmitted to a torque exerted by the strut 370
outward against the vessel wall. This outward torque can be
resolved into a product of the outward force against the vessel
wall and the strut length 390. The hinge 380 & 455 can
therefore transfer its moment to the strut 370 which then exerts an
outward force upon the vessel wall to hold it outwards.
[0162] The present attachment anchor 245 can be optimally suited to
provide a smaller strut length 390 and a greater number of struts
370 and nodes 365 in order to apply a specific outward force
against the vessel or tubular member wall for a nondeployed
attachment anchor perimeter 449 and a deployed attachment anchor
perimeter 451. Strut length has an effect upon the flexibility
characteristics of the attachment anchor in a crush deformation
mode. A longer strut length provides the attachment anchor with a
greater percentage of the perimeter of the attachment anchor in a
deployed state that is associated with the struts in comparison to
the nodes. Since the struts are more flexible in a crush
deformation than the nodes, longer strut length provides a greater
flexibility in forming an oval shape. To provide an attachment
anchor having longer strut length with the same crush flexibility
as a shorter strut, the strut radial dimension would be increased
to provide the appropriate bending moment in the radial direction.
The strut width can be reduced to provide the appropriate
resistance to bending in the attachment anchor surface during
expansion deformation. The attachment anchor 245 has nodes with
hinges 380 & 455 that are machined into the metal rather than
having a wire formed into a loop such as found in prior art
attachment means. Each hinge 380 & 455 can be machined with a
smaller hinge width radius of curvature 386 than can be formed from
a round wire of diameter similar in magnitude to the hinge width
420. Furthermore the hinge 380 & 455 of the present invention
can generate a greater moment than can be generated by a round wire
as found in prior art attachment means. The struts 370 are
similarly formed by machining to form struts 370 of approximately
similar or smaller strut width 430 than the diameter of a round
wire of similar strength or moment of inertia allowing the struts
370 to be aligned adjacent to each other or touching each other and
parallel to each other in a close packed conformation in a
nondeployed state. In a deployed state the present attachment
anchor 245 can provide a greater outward force against the vessel
wall due to the greater moment generated by each hinge 380 &
455. The present attachment anchor 245 can be formed with a
nondeployed attachment anchor length 400 that is less than
approximately 0.20 to 0.30 inches for abdominal aortic aneurysm
repair of an aorta with a deployed diameter 237 of approximately 25
millimeters and less than approximately 0.10 to 0.20 inches for an
attachment anchor length 400 in vessels that are less than
approximately 6 millimeters in diameter. The number of struts 370
along the deployed attachment anchor perimeter 451 of the
attachment anchor 245 can be at least approximately 26 to 32 for
abdominal aortic aneurysm repair of an aorta with a 25 millimeter
diameter and at least approximately 14 to 20 for use in a vessel of
approximately 6 millimeter diameter.
[0163] Alternately, the attachment anchor 245 of the present
invention can be formed of large strut length 390 greater than
approximately 0.3 inches, a thinner strut width 430, and a larger
strut radial dimension 435 and having a lesser number of struts 370
than the approximately 14 struts stated for the previous
embodiment. The attachment anchor 245 of the present invention can
be formed with any number of struts 370 and with any strut length
390 that is suited to a particular application. The hinge 380 &
455 of the present invention can provide a greater moment than the
moment provided by prior art round wire zig zag attachment means
and other prior art attachment means. Therefore the hinge 380 &
455 of the present invention can transfer a large torque to a strut
370 of larger strut length 390 than the length of other prior art
round wire struts and provide a greater outward force against the
blood vessel to hold it outward than a round wire attachment means.
The attachment anchor 245 of the present invention can therefore be
used to provide a short or a long strut length 390 with varying
strut radial dimensions and strut widths. The number of struts 370
can similarly be varied such that an attachment anchor 245 with
longer struts 370 can be formed with less struts 370 than other
prior art attachment means.
[0164] The deployment angle 405 of the present attachment anchor
245 is generally intended to be small enough such that the change
in nondeployed attachment anchor length 400 in a nondeployed state
to a deployed attachment anchor length 395 in a deployed state does
not affect the positioning of the attachment anchor 245 within the
blood vessel prior to deploying it to a deployed state. A total
deployment angle 405 of less than 60 degrees results in a change in
the attachment anchor length from the nondeployed state to the
deployed state of approximately 15 percent. The present attachment
anchor 245 can be designed such that the hinge 380 & 455 will
provide any deployment angle 405 from 1 to 80 degrees. To maintain
a small change in attachment anchor length from a nondeployed state
to a deployed state a deployed angle of less than 45 degrees can be
attained by the present attachment anchor 245. Alternately, in
order to provide the attachment anchor 245 with the least number of
nodes 365 and struts 370 while still providing for the greatest
expanded deployed attachment anchor diameter 320, it is desirable
to provide a deployment angle 405 that is greater than 45 degrees.
The hinge 380 & 455 of the present invention can be formed from
a metal of large Young's modulus as stated earlier. The hinge 380
& 455 can be formed of a thin hinge width 420 and a long hinge
length 415 such that the moment maintained by the hinge 380 &
455 will still be adequate even at a large bending deformation
angle or deployment angle 405. Thus the hinge 380 & 455 of the
present invention can supply adequate outward force at a deployment
angle 405 greater than 45 degrees and up to 180 degrees.
[0165] The attachment anchor 245 of the present invention can have
one or two hinges 455 positioned on each node 365. For the
embodiment with two hinges 455, the hinges 455 can be equivalent to
each other in dimension and perform similarly to having one larger
hinge such as a single hinge 380 of another embodiment.
Alternately, each hinge 455 on a particular node can be formed with
a different hinge length 415 or hinge width 420 than the other. The
moment that is generated by each hinge 455 after exposure to a
similar bending deformation would therefore be different. The
struts 370 joined via transition regions to each of the hinges 455
can be adjusted such that the strut lengths 390 are different. This
embodiment of an attachment anchor 245 with struts 370 of different
strut length 390 connected to the same node can apply a uniform
force outward against the blood vessel wall although the longer
strut could undergo a greater amount of bending deformation in a
crush mode.
[0166] An alternate embodiment for the attachment anchor 245 of the
present invention is shown in a nondeployed state in FIG. 10D and
in a deployed state in FIG. 10E. The attachment anchor 245 is
formed entirely out of nodes 365 and struts 370 arranged to form a
ring with a cylindrical shape. The attachment anchor 245 of this
embodiment has a uniformly curved attachment anchor surface 404 in
its deployed state shown in FIG. 10D. The attachment anchor 245 of
this embodiment has the same description and function for the
hinges 455, hubs 457, and struts 370 as were described and shown in
FIGS. 10A-10C. The hinges 455 have hinge dimensions that allow the
hinges to undergo expansion deformation within the uniformly curved
attachment anchor surface 404 but will not deform in a radial
direction due to a crush deformation. The struts 370 have strut
dimensions that allow them to bend elastically as the attachment
anchor 245 bends to an oval shape during crush deformation but the
struts 370 will not bend in the uniformly curved attachment anchor
surface 404. Barbs 250 can be a component of any of the nodes 365
in a manner described for the embodiment shown in FIGS. 10A-10C.
This embodiment can be a balloon-expandable or a self-expandable
attachment anchor 245. The metal used to form the attachment anchor
245 along with the dimensions used for the hinge 455 determine
whether a plastic deformation or an elastic deformation of the
hinge 455 will occur during the expansion deformation from a
nondeployed state to a deployed state as described earlier for the
embodiment shown in FIGS. 10A-10C. This embodiment (see FIGS. 10D
and 10E) of the attachment anchor 245 provides an improved
stability in maintaining a cylindrical shape over the embodiment
shown in FIG. 10A-10C due to the closed diamond shaped structure or
closed configuration formed by the nodes 365 and struts 370 of the
present embodiment in comparison to the series alignment of nodes
and struts shown in the embodiment of FIGS. 10A-10C. All reference
numerals correspond to those elements previously or otherwise
described.
Attachment Anchor with Barbs
[0167] FIGS. 11A-11D shows another embodiment for the attachment
anchor 245 of the present invention with barbs 250 joined to nodes
365 along an attachment anchor outside end 458. The node 365 of
this embodiment as shown in FIGS. 11B and 11D include the hinge
380, the transition regions 410, and the barb 250. The barbs 250
can be contiguously joined to any portion of a node 365 including a
hub 457 or a hinge 380 & 455. FIG. 11A shows the attachment
anchor 245 of this embodiment in a nondeployed state or an
insertion state. An isometric view of a portion of the attachment
anchor 245 shown in FIG. 11A in a nondeployed state is shown in
FIG. 11B. The barb 250 has been folded over into the intranodal
opening 385 and is being held in a protected conformation by the
struts 370 and the transition regions 410. FIG. 11C shows the
attachment anchor 245 in a deployed or implanted state with barbs
250 extending outward to the side. An isometric view of a portion
of the attachment anchor 245 shown in FIG. 11C is shown in FIG.
11D. As the struts 370 expanded during the deployment of the
attachment anchor 245, they released the barb 250 allowing the barb
250 to extend outwards in its fully extended state. The barbs 250
of the present attachment anchor 245 are folded and protected when
the attachment anchor 245 is in a nondeployed state. As the
attachment anchor is expanded, the barbs 250 are completely
released by the struts 370 such that they extend outward to their
fullest extent. This is in contrast to the barbs of other prior art
attachment means that are deployed an increasing amount as the
attachment means is extended to a greater amount. The barbs 250 of
the present invention are designed to deploy fully and extend
outward once the attachment anchor 245 has been extended enough
such that the struts 370 allow the barbs 250 to be released from
its folded position as shown in FIG. 11B. When the attachment
anchor 245 is expanded by either allowing it to self-expand or
through expansion with a dilitation balloon, each of the barbs 250
is released by the struts 370 and transition regions 410 and the
intranodal opening 385 and allowed to extend outwards. The barbs
250 provide anchoring of the attachment anchor 245 and the
intravascular tubular member 85 of the present invention or other
intravascular stent-graft to the aortic vessel wall or other
arterial wall. Such anchoring can help to prevent migration of the
intravascular tubular member and help to prevent further aneurysmal
dilitation of the aorta. In a nondeployed state the barbs 250 are
folded up such that they cannot catch or snag on the intravascular
tubular member 85 or other intravascular stent-graft device or
tissue components. The barbs 250 can be machined using mechanical,
laser, electrochemical, or other machining techniques as described
for machining the attachment anchor into the same metal tube that
forms the attachment anchor 245. The barbs 250 can be machined such
that they are continuous and contiguous with each node 365 without
the need for an attachment of the barbs 250 to the nodes 365. The
barbs 250 can be contiguous with the hinges 380 or with the hubs
454 if such hubs are present on the node. Each barb 250 is
considered to be a component of the node 365. The strength of the
barbs 250 is therefore increased and their resistance to stress
cracking or fracture will be reduced. Attachment wires or barbs
used in other prior art attachment devices have been attached by
welding, brazing, or other techniques and have suffered problems
with metal failure and fracture of the attachment wires. The
present attachment anchor 245 does not have such welds, brazes, or
other forms of attachment of the barbs 250 to the attachment anchor
245.
[0168] FIG. 12A shows the attachment anchor 245 attached near the
inlet end 145 and near the outlet end 148 of an intravascular
tubular member 85. The intravascular tubular member can be any
surgical vascular graft, intravascular tubular member, other
intravascular stent-graft, or other vascular tubular member that is
in need of an attachment anchor 245 to hold either the inlet end
145 or the outlet end 148 of the vascular tubular member into
contact with a native artery or vein. The intravascular tubular
member 85 can be formed from ePTFE, knitted or woven polyester,
polyurethane, silicone or any other material use in surgical
vascular grafts, intravascular grafts, intravascular stent-grafts,
or vascular conduits. The intravascular tubular member 85 can be a
straight or bifurcated vascular graft, intravascular graft, or
intravascular stent-graft. The attachment anchor 245 holds the
intravascular tubular member outward against the native vessel
wall, prevents leakage of blood between the vascular tubular member
and the native lumen, and prevents distal migration of the vascular
tubular member. The attachment anchor 245 can be attached to the
intravascular tubular member with securing fibers 255. Such
securing fibers 255 can include sutures, polyester fiber,
polytetrafluoroethylene fiber, metal wire, staples, biocompatible
and biostable fiber, or other securing means. The securing fibers
255 can extend through and attach to any or all of the intranodal
openings 385 found in the nodes 365 of the attachment anchor 245.
The attachment anchor 245 positioned at the inlet end 145 can have
barbs 250 attached or the attachment anchor 245 can be one without
barbs 250 as shown on the outlet end 148. If the attachment anchor
245 has barbs 250, the wall of the intravascular tubular member 85
or other prior art intravascular stent-graft can be attached to the
attachment anchor 245 such that the barbs 250 can extend outward
without snagging the intravascular tubular member, or other device
component such as the delivery sheath 225 (see FIGS. 2C, 2D, 4C,
and 4D). If the attachment anchor 245 does not have barbs 250 such
as the attachment anchor 245 positioned, for example, at the outlet
end 148, the attachment anchor 245 can be attached to the wall of
the intravascular tubular member such that it does not protrude
beyond the outlet end 148. The securing fibers 255 can extend
through the intranodal openings 385 of the attachment anchor 245
without pinching or cutting the securing fibers 255.
[0169] FIG. 12B shows the attachment anchor 245 attached near the
inlet end 145 and near the outlet end 148 of the straight
intravascular folded tubular member 95. The straight intravascular
folded tubular member 95 can be the intravascular tubular member 85
shown in FIGS. 2A-2D that can be in need of an attachment anchor
245 to hold either the inlet end 145 or the outlet end 148 of the
straight folded intravascular tubular member 85 into contact with a
native artery such as the abdominal aorta or with a vein. The
attachment anchor 245 is held to the straight intravascular folded
tubular member 95 with securing fibers 255 as described in FIG.
12A. The attachment anchor 245 positioned at the inlet end 145 can
have barbs 250 attached or the attachment anchor 245 can be one
without barbs 250. If the attachment anchor 245 has barbs 250, the
straight proximal tubular section wall 170 can be attached to the
attachment anchor 245 such that the attachment anchor 245 extends
beyond the inlet end 145 of the straight intravascular folded
tubular member 95 and the barbs 250 can extend outward without
snagging the straight intravascular folded tubular member 95. If
the attachment anchor 245 does not have barbs 250 such as the
attachment anchor 245 positioned at the outlet end 148, the
attachment anchor 245 can be attached to the distal tubular section
wall 190 of the straight intravascular folded tubular member 95
such that it does not protrude beyond the outlet end 148. The
securing fibers 255 can extend through the intranodal opening 385
of the attachment anchor 245 without pinching or cutting the
securing fiber 255.
[0170] FIG. 12C shows the attachment anchor 245 attached near the
inlet end 145 and near each outlet end 148 of the bifurcated
intravascular folded tubular member 260. The bifurcated
intravascular folded tubular member 260 can be the bifurcated
intravascular folded tubular member 260 shown in FIG. 5 that is in
need of an attachment anchor 245 to hold either the inlet end 145
or the outlet end 148 of the bifurcated intravascular folded
tubular member 260 into contact with a native artery such as the
abdominal aorta. The attachment anchor 245 is held to the
bifurcated intravascular folded tubular member 260 with securing
fibers 255 as described in FIG. 12A. It is preferred that the
attachment anchor 245 positioned at the inlet end 145 may have
barbs 250 attached although the attachment anchor 245 can be one
without barbs 250. If the attachment anchor 245 has barbs 250, the
wall of the bifurcated intravascular folded tubular member 260 can
be attached to the attachment anchor 245 such that the attachment
anchor 245 extends beyond the inlet end 145 of the bifurcated
intravascular folded tubular member 260 and the barbs 250 can
extend outward without snagging the bifurcated intravascular folded
tubular member 260. If the attachment anchor 245 does not have
barbs 250 such as shown for each attachment anchor 245 that is
positioned at each outlet end 148, the attachment anchor 245 can be
attached to the distal tubular section wall 190 of the bifurcated
intravascular folded tubular member 260 such that it does not
protrude beyond the outlet end 148. The securing fibers 255 can
extend through the intranodal opening 385 of the attachment anchor
245 without pinching or cutting the securing fibers 255.
[0171] The straight intravascular folded tubular member 95 and
bifurcated intravascular folded tubular member 260 with the
attachment anchor 245 shown in FIGS. 12B and 12C have specific
advantages that provide these embodiments with distinct advantages
when used together. The straight intravascular folded tubular
member 95 and bifurcated intravascular folded tubular member 260
can be in need of an attachment means 87 that is attached to the
intravascular folded tubular member and provides for better
attachment than that provided by other prior art attachment means.
The straight intravascular folded tubular member 95 and bifurcated
intravascular folded tubular member 260 with the attachment anchor
245 of the present invention provides the inlet end 145 and outlet
end 148 with a more firm anchoring to the native vessel than with
other prior art attachment means. The short nondeployed attachment
anchor length 400 allows the attachment anchor 245 to be placed
precisely where it is needed. For example, in the treatment of
abdominal aortic aneurysm 5 it can be important to place the
attachment anchor 245 as close as possible to the left renal artery
45 and right renal artery 50 where the abdominal aortic wall 70 is
not distended (see FIGS. 1A and 1B). Other prior art attachment
means with a longer length often can extend into the thrombotic
lining of the aorta where it is not possible to provide a firm
attachment to the vessel wall. The short deployed attachment anchor
length 395 (see FIG. 9C) allows the attachment anchor 245 of the
present invention to have a greater number of nodes 365 positioned
around the circumference to allow for a better attachment to the
native vessel. The increased number of nodes 365 offers the
opportunity of the present attachment anchor 245 to have a greater
number of barbs 250 attached. In a nondeployed state, the barbs 250
are protected such that snagging of the barb 250 on the
intravascular folded tubular member or delivery sheath 225 (see
FIGS. 2C, 2D, 4C, and 4D) is not possible. Upon deployment the
increased number of barbs 250 provides an improved attachment to
the vessel wall that can further reduce the chances for further
aneurysm dilation and can reduce the chances for distal migration
of the intravascular folded tubular member. Once the inlet end 145
of the straight intravascular folded tubular member 95 (see FIG.
12B) or bifurcated intravascular folded tubular member 260 is
attached to the native vessel proximal to the vessel injury using
the attachment anchor 245 it is more likely to remain attached
without migration as the outlet end 148 of each distal tubular
section 130 is placed into appropriate location at a site distal to
the vessel injury. Placement of the outlet end 148 causes each
folded tubular section 125 to unfold and can place a force on the
attachment anchor 245 at the inlet end 145 to move distally.
Therefore the attachment anchor 245 of the present invention
provides the necessary advantages to specifically improve the
function of the straight intravascular folded tubular member 95 or
bifurcated intravascular folded tubular member 260. Furthermore,
since the straight intravascular folded tubular member 95 or
bifurcated intravascular folded tubular member 260 is a one-piece
construction and not a modular system such as many prior art
devices, blood leakage cannot occur except at an inlet end 145 or
outlet end 148. Placing the attachment anchor 245 at the inlet end
145 and at each outlet end 148 will provide a better seal of the
intravascular folded tubular member with the native lumen of the
blood vessel. This is due to the increased number of struts 370
(see FIG. 9A) and nodes 365 that provide a more uniform force along
the circumference of the intravascular folded tubular member. The
resulting straight intravascular folded tubular member 95 and
bifurcated intravascular folded tubular member 260 will provide a
leak free one-piece intravascular folded tubular member that can
isolate an aneurysm better than a multi-tubular modular system.
Other prior art one-piece systems that cannot provide a positive
length determination in situ as with the present intravascular
folded tubular member. These prior art one-piece systems require an
estimation of their length in comparison to the actual vessel
lesion length prior to implant. This often results in placing the
inlet end 245 or outlet end 148 in a vessel location that is either
thrombus 60 laden, blocks a side branch vessel such as an internal
iliac artery 80 in the case of abdominal aortic aneurysm repair
(see FIGS. 1A and 1B), or is of inappropriate vessel diameter to
match the diameter of the prior art device. The present straight
intravascular folded tubular member 95 (see FIG. 12B) or bifurcated
intravascular folded tubular member 260 (see FIG. 12C) can have its
inlet end 145 and each outlet end 148 placed precisely after the
intravascular folded tubular member has been delivered within the
blood vessel. The inlet end 145 and outlet end 148 of the present
intravascular folded tubular member can therefore be placed in a
vessel location that is better able to form a leak free seal if it
is combined with the improved attachment anchor 245 of the present
invention.
Wall Structure
[0172] The wall structure for a surgical vascular graft, an
intravascular tubular member, an intravascular folded tubular
member, or other vascular tubular member, can be formed by weaving
fibers or strands of polymeric material, metallic material, or
other material to form a woven vascular tubular member 460 as shown
in FIGS. 13A-13M. The description of these figures and reference to
individual components and their reference numerals will proceed
together. The woven vascular tubular member 460 can have a tight
tubular weave that will not leak blood serum or blood cellular
elements after implant. Generally one or more circumferential
fibers or circumferential strands 465 are woven with a gradual
helical wind in a generally circumferential direction 470 and a
plurality of axial fibers or axial strands 475 are woven in a
generally axial direction 398 and interface or cross over the
circumferential strands 465 as shown in FIG. 13A. The axial strands
475 or circumferential strands 465 can be formed of a single
filament or can be formed of many filaments 483 as shown in FIG.
13B. Following the formation of the woven vascular tubular member
460 the axial strands 475 tend to reorient slightly to become
perpendicular to the generally circumferential strands 465 and will
have a small helical wind to them. In the weave of the strands the
points where the generally circumferential strands 465 cross over
the generally axial strands 475 will be referred to as crossover
points 485 (see FIG. 13A). The woven vascular tubular member 460
can be used as a surgical vascular graft for surgical implant or
can be used as an intravascular tubular member 85 that can be
delivered and implanted percutaneously or delivered through a
delivery sheath 225 (see FIG. 4D) placed in a blood vessel that was
accessed through a small cutdown procedure to access the blood
vessel.
[0173] Polymeric strands used to weave a woven vascular tubular
member 460 can be formed of a single monofilament strand 490 and
are referred to as polymeric monofilament strands 490 or
monofilament fibers as shown in the woven monofilament wall
structure of FIG. 13C. A woven vascular tubular member 460 formed
from polymeric monofilament strands 490 will have small gaps or
leakage sites 495 for blood leakage at or near the monofilament
strand crossover points 498. The size of the leakage sites 495 is
dependent upon the monofilament strand diameter 500 as well as how
tightly they are packed. The size of the gaps or leakage sites 495
can be approximately as large as the monofilament strand diameter
500. To prevent blood cellular elements from passing through the
leakage sites 495, the gaps cannot be significantly larger than the
cellular elements found in the blood. With small leakage sites 495,
red blood cells and platelets can become trapped and create
thrombosis that will prevent leakage from that gap or leakage site.
Red blood cells are typically 8 micrometers in the larger diameter
of the red blood cell. Monofilament strands 490 with a monofilament
strand diameter 500 of only 8 micrometers would be too small, too
weak, and impractical to weave or braid into a vascular graft,
intravascular tubular member 460, or woven vascular tubular member
460. Fibers or strands formed from many smaller filaments 483 can
form a multifilament strand 510 that will provide the necessary
sealing at multifilament crossover points 513 of a multifilament
strands 510 in generally the axial direction 398 with multifilament
strands 510 in generally the circumferential direction 470; these
multifilament strands form a woven multifilament strand wall
structure shown in FIG. 13B.
[0174] A multifilament strand formed from approximately 3 to 100
filaments 483 will deform in the crossover points 485 and will seal
the gaps or leakage sites 495 at or near crossover points 485 in a
weave of the multifilament strands 510 as shown in FIG. 13B. A
filament diameter 515 can range from approximately 1 to 200
micrometers and the multifilament strand diameter 520 or fiber
diameter can range from approximately 0.001 to 0.040 inches (see
FIG. 13D). The multifilament strand 510 or fiber will have
significant flexibility due to the small filament diameter 515 and
the multifilament strand will have strength due to the presence of
many filaments 483. At the crossover points 485 the multifilament
strands 510 will spread the filaments 483 out to form a more
flattened cross section for the strand and this spreading out of
the filaments 483 will reduce the size of the gap or leakage site
495 such that leakage of blood will not occur as shown in FIG.
13B.
[0175] Polymeric strands can be formed from filaments 483 of
expanded polytetrafluoroethylene (ePTFE), polyester, polyethylene
terephthalate, polyurethane, silicone, or copolymers or block
copolymers involving these polymers or filaments 483 formed from
other polymeric materials that are suitable for implant within the
body from the standpoint of biocompatibility, biostability,
strength, flexibility, and other properties. An expanded
polytetrafluoroethylene filament 525 (ePTFE filament 525) as shown
in FIG. 13E is formed from paste extrusion and can be stretched
under high temperature, and sintered at very high sintering
temperature to increase the axial strength thereby forming an ePTFE
filament 525 that is well suited to forming an ePTFE multifilament
strand 510 that can be woven into the wall structure of the present
invention. The wall structure for a vascular tubular member 83
includes the general material of construction, such as polymeric or
metallic, and physical description of the wall such as woven or
braided. Each ePTFE filament 525 can include one or more expanded
polytetrafluoroethylene microfilaments 530 (ePTFE microfilaments
530) within a cross section; such microfilaments tend to contain
significant polymeric molecule orientation along its length which
contributes to its excellent axial strength. An ePTFE filament 525
can contain nodal regions 535 of polytetrafluoroethylene which can
provide sites of junction between ePTFE microfilaments 530 such
that ePTFE microfilaments 530 are connected together with
polytetrafluoroethylene to form a single ePTFE filament 525 that
cannot be easily divided into individual ePTFE microfilaments 530
throughout the length of the ePTFE filament 525. The expanded
polytetrafluoroethylene multifilament strand 510 (ePTFE
multifilament strand 510) for use in weaving surgical vascular
grafts, intravascular tubular members 85, or other vascular tubular
members 83 can have a multifilament strand diameter 520 (see FIG.
13D) that ranges from approximately 0.001 to 0.040 inches, an
expanded polytetrafluoroethylene filament diameter 540 (ePTFE
filament diameter 540) that ranges from approximately 1-200
micrometers, and an expanded polytetrafluoroethylene microfilament
diameter 545 (ePTFE microfilament diameter 545) that ranges from
approximately 0.01 to 200 micrometers. The ePTFE multifilament
strand 510 used in larger diameter surgical vascular grafts,
intravascular tubular members, or vascular tubular members ranging
in diameter from approximately 8 to 30 millimeters such as those
used in abdominal aortic aneurysm repair has a preferred
multifilament strand diameter 520 that ranges from approximately
0.003 to 0.040 inches, a preferred ePTFE filament diameter 540 that
ranges from approximately 2.5 to 200 micrometers, and a preferred
expanded polytetrafluoroethylene microfilament diameter 545 (ePTFE
microfilament diameter 545) that ranges from approximately 0.01 to
200 micrometers. In weaving a surgical vascular graft,
intravascular tubular member, or vascular tubular member for
coronary or other small diameter vascular applications with a
smaller vascular tubular member diameter ranging from approximately
a 3 to 6 millimeter diameter, for example, an ePTFE multifilament
strand 510 can have a preferred multifilament strand diameter 520
that ranges from 0.001 to 0.020 inches, a preferred ePTFE filament
diameter 540 that ranges from approximately 1 to 200 micrometers,
and a preferred ePTFE microfilament diameter 545 that ranges from
approximately 0.01 to 200 micrometers. An ePTFE multifilament
strand 510 of the preferred embodiments contains at least three
ePTFE filaments 525 or at least three ePTFE microfilaments 530 in
order to provide adequate sealing at multifilament strand crossover
points 513 and each filament is comprised of one or more
microfilaments.
[0176] A surgical vascular graft or vascular implant 82,
intravascular tubular member 85, or vascular tubular member 83
formed from weaving multifilament strands 510 of polyester or other
polymeric material could have a wall structure for the vascular
tubular member 83 of the present invention formed from
multifilament strands 510 and filaments 483 with diameters having a
similar range to that discussed above for the
polytetrafluoroethylene multifilament strands 510 and ePTFE
filaments 525.
[0177] Polymeric multifilament strands 510 used in forming the
woven wall structure of some embodiments of the present invention
can extend along their linear axis 550 with a generally linear or
straight shape forming straight multifilament strands 555 (see FIG.
13F). The strands can be formed of straight filaments 560 that also
have a linear or straight shape along their linear axis 550.
Polymeric multifilament strands 510 formed from such straight
filaments 560 that are straight will not in general have
significant stretch characteristics in the direction of their
linear axis 550. Alternately, polymeric multifilament strands 510
can be formed from curved filaments 570 that have a zig zag shape,
a sinusoidal shape, helical shape, or some other form of curved
shape extending in the direction of their linear axis 550 forming a
curved multifilament strand 573 as shown in FIG. 13G. A curved
multifilament strand 573 formed from such curved filaments 570 will
exhibit extension or stretch characteristics in the linear axis 550
direction of the fiber (see FIG. 13G). The amount of zig zag or
curved shape that can be formed into the curved filaments 570 is
such that it can provide the curved multifilament fiber or curved
multifilament strand 573 with a stretch amount ranging from
approximately one to fifty percent of its length along its linear
axis 550. Such curved filaments 570 can be formed by thermal,
chemical, or mechanical treatment of the filaments 483 of the
strand to form a set shape found in the curved filaments 570 with
at least some temporary memory of the set shape under normal
conditions of use for the vascular or intravascular graft. A
straight expanded polytetrafluoroethylene filament 575 (see FIG.
13E) containing straight expanded polytetrafluoroethylene
microfilaments 580 can be exposed to high temperature while fixing
or holding a specific length along its axis 550 to generate a
curved shape for the microfilaments as shown in FIG. 13H. This
specific length is shorter than its elongated length when exposed
to axial stress. This high temperature is lower than the very high
temperature used during the sintering step mentioned earlier. This
process results in a curved expanded polytetrafluoroethylene
filament 585 with curved expanded polytetrafluoroethylene
microfilaments 590. The curved shape for the curved ePTFE
microfilaments 590 and curved ePTFE filament 585 will not easily
return to a straight shape unless exposed to high temperature while
held under stress. Expanded polytetrafluoroethylene multifilament
strands 510 formed from curved ePTFE filaments 585 that have curved
ePTFE microfilaments 590 will provide significant axial stretch.
Thermal treatment can also be applied to polyester multifilament
strands 510 or to other polymeric multifilament strands 510 to form
a curved filaments 570 and curved multifilament strands 573 using
techniques known in the textile industry.
[0178] A surgical vascular graft, an intravascular tubular member
85, or other vascular tubular member can be formed by weaving ePTFE
multifilament strands 510 or other polymeric multifilament strands
510 into a tubular form. The multifilament strands 510 can either
have straight ePTFE filaments 575 or curved ePTFE filaments 585 and
weaving a vascular tubular member 83 out of curved multifilament
strands 573 will give stretch characteristics in the direction or
their linear axis 550 as they are woven in the axial direction 398,
circumferential direction 470, or both directions (see FIGS. 13B
and 13G). An embodiment of a vascular tubular member formed from
ePTFE multifilament strands 510 of curved ePTFE filaments 585 is
shown in FIG. 13I. Curved multifilament strands 573 formed from
curved ePTFE filaments 585 could be woven in the circumferential
direction 470 (see FIG. 13A) with straight multifilament strands
555 in the axial direction. Such a structure approximates the
radial compliance found in native blood vessels and can provide
improved healing at the junction sites of the vascular tubular
member with the native vessel. Expanded polytetrafluoroethylene
curved multifilament strands 573 can be woven in the axial
direction 398 with straight multifilament strands 555 in the
circumferential direction 470. Such a wall structure can provide
improved flexibility with excellent kink resistance. Curved
multifilament strands 573 formed from curved ePTFE filaments 585
can be woven in each direction to provide a woven vascular tubular
member 460 with stretch characteristics in both directions (see
FIG. 13I). Such a wall structure can have both radial and axial
compliance and be resistant to kinking. Such a woven vascular
tubular member 460 could be used for standard surgical arterial
reconstruction, as a component of a stent-graft, or a the wall
structure for and intravascular tubular member for treatment of
vascular injury such as abdominal aortic aneurysm repair. A similar
vascular tubular member can be woven from straight or curved
polymeric multifilament strands 510 of polyester or other polymer
to form a vascular tubular member similar to FIG. 13I.
[0179] Circumferential strands 465 and axial strands 475 formed of
metal material can be woven along with the multifilament polymeric
strands 595 formed of filaments 483 of polymeric material in the
generally circumferential direction 470, the generally axial
direction 398, or both directions as shown in FIG. 13J to form the
woven vascular tubular member 460 shown in FIG. 13A. Metallic
strands 600 woven along with the polymeric strands 595 can be a
metallic monofilament strand 490 of a circular cross section or
metallic multifilament strands 510 formed from a plurality of
smaller diameter metal filaments 483. The metallic strands 600 can
be formed out of stainless steel, Nitinol, tantalum, titanium, an
alloy of these metals, other metal used in the formation of
implanted stents, or other metal capable of being implanted and
having adequate strength to support the stresses found in a
surgical vascular graft, intravascular graft, or vascular tubular
member. The metallic strands 600 can have a generally linear or
straight shape in the direction of their linear axis 550 forming
metallic straight monofilament strands 605 or metallic straight
multifilament strands 555 (see FIGS. 13K and 13F). In a preferred
embodiment the metallic strands 600 are metallic monofilament
strands 490 and are woven along with the multifilament polymeric
strands 595 to form a wall structure for the woven vascular tubular
member 460 as shown in FIG. 13J. At the metal to metal crossover
points 610, leakage sites 495 can be created that could allow blood
leakage out of the woven vascular tubular member 460 formed of the
wall structure of this embodiment.
[0180] Alternately, the metallic strands 600 can be bent or formed
by mechanical, chemical, or thermal methods into a zig zag,
sinusoidal, helical, or other curved shape forming a metallic
curved monofilament strand 615 or a metallic curved multifilament
strand 570 as shown in FIGS. 13L and 13G. The metallic curved
monofilament strand 615 has a direction of its linear axis 550
determined by the overall direction of the curved monofilament
strand 615 along its length. The metallic curved monofilament
strand 615 is able to extend in a generally linear axis 550
direction by an amount that ranges from one to fifty percent of its
generally axial length. The metallic monofilament strand diameter
500 or multifilament strand diameter 520 can range from 0.001 to
0.020 inches. The metallic monofilament strand 490 can provide an
outward expansion force to the wall structure of the woven vascular
tubular member 460 and provide resistance to axial compressive
forces generated by the native tissue surrounding the woven
vascular tubular member 460.
[0181] The wall structure as shown in FIG. 13J for a surgical
vascular graft, intravascular graft, an intravascular folded
tubular member, or a vascular tubular member 83 used in the
treatment of abdominal aortic aneurysm or the treatment of other
large diameter vessels with a diameter of 8 to 30 millimeters, the
metallic monofilament strand diameter 500 (see FIG. 13C) is
preferably approximately 0.003 to 0.020 inches. For a vascular
graft or intravascular graft for treatment or coronary vessels or
vessels less than 6 millimeters, the preferred metallic
monofilament strand diameter 500 or metallic multifilament strand
diameter 520 is approximately 0.001 to 0.016 inches. The presence
of metallic strands 600 in the circumferential direction 470 (see
FIG. 13J) provides the surgical vascular graft, intravascular
tubular member 85, or vascular tubular member 83 made from this
wall structure with the property of exerting an outward force
against the native vessel, holding the native vessel outward in an
open and patent conformation, and resisting against vessel
contraction due to tissue scarring and healing. Due to the
circumferential direction 470 of some of the metallic strands 600,
the amount of outward extensional force generated by a metallic
strand 600 of smaller diameter is greater than that provided by a
larger diameter but more zig zag or bent metallic strands such as
those disclosed in prior art stent-graft devices. The metallic
strands 600 in the axial direction 398 provide the surgical
vascular graft, or intravascular graft formed from this wall
structure with resistance to compressive length changes. The
intravascular tubular member 85 or vascular tubular member 83 as
shown in FIGS. 2A, 2B, 4A, 4B, and in other embodiments can have a
woven wall structure as described in the embodiments of FIGS.
13A-13M and can undergo a change in diameter from a smaller or
nondeployed diameter 305 in its nondeployed state as it is being
inserted into the vascular system to a larger or deployed diameter
237 in its deployed state after it is implanted in the appropriate
location. The woven vascular tubular member 460 (see FIG. 13A) of
the present invention can be formed entirely out of woven metallic
strands 600.
[0182] In a preferred embodiment, metallic strands 600 formed of
straight 605 and curved 615 monofilaments of metallic material are
woven along with the multifilament polymeric strands 595 in either
the axial direction 398, the circumferential direction 470, or both
directions as shown in FIG. 13J. When metallic strands 600 are
woven along with the multifilament polymeric strands in the
circumferential direction 470 as shown in FIG. 13J, the number of
metallic strands per length of woven vascular tubular member 460
can range from one metallic strand 600 approximately every 0.060
inches to one metallic strand 600 every 1.5 inches. It is preferred
to place a metallic strand 600 in the circumferential direction 470
approximately every 0.10 to 0.90 inches along the length of the
woven vascular tubular member 460. For the metallic strands 600 in
the axial direction 398, the spacing range between metallic strands
600 in the circumferential direction 470 is the same as the spacing
range along the axial direction 398 of the woven vascular tubular
member 460 with a wall structure as shown in FIG. 13J. This spacing
for metallic strands applies to the wall structures which are shown
in FIGS. 14, 16A-16C, 17A-17C, 18A, and 18B.
[0183] The metallic strands 600 can be formed of a metal with a
high yield strength that will remain elastic during the deployment
of the intravascular tubular member from the nondeployed state to
the deployed state. The high yield strength metallic strands 600
will provide the intravascular graft with a self-expandable
property. Such an intravascular tubular member can be contained
completely within a delivery sheath 225 (see FIGS. 2C, 2D, 4C, and
4D) during the delivery of the intravascular tubular member 85 to
the site of the vessel lesion that is to be treated by the
intravascular tubular member. Upon release of the self-expandable
intravascular tubular member 85 from the delivery sheath 225, it
expands outward to its vascular tubular member deployed diameter
237 and the woven wall structure of the present invention is placed
into contact with the native vessel or thrombus.
[0184] Alternately, the metallic strands 600 shown in FIG. 13J can
be formed from a metal with a yield strength that will allow
plastic deformation to occur during the deployment of the woven
intravascular tubular member 460. This embodiment of the woven
intravascular tubular member 460 formed of this wall structure can
be expanded internally by a mechanical expanding means such as a
balloon of a balloon dilitation catheter to force the intravascular
tubular member 85 to expand from its smaller vascular tubular
member nondeployed diameter 238 to a larger vascular tubular member
deployed diameter 237. The metallic strands of this embodiment
undergo a plastic deformation during the deployment from the
vascular tubular member nondeployed diameter 238 to the vascular
tubular member deployed diameter 237 as shown in FIGS. 2B, 2C, 4B,
and 4D.
[0185] The metallic strands 600 used in the wall structure of the
present invention as shown in FIG. 13J can be flattened metallic
strands 620 with approximately a rectangular cross sectional shape
(see FIG. 13M). The advantages of this form of metallic strand is
that it provides a closer packing with another flattened metallic
strands 620 at a flattened crossover point 623 in a weave that
contains flattened metallic strands 620 with a smaller gap and
smaller leakage site 495. The flattened metallic strands 620 can be
woven along with multifilament polymeric strands 595 as shown in
FIG. 13J such that minimal blood leakage will occur at crossover
points. Flattened metallic strands 620 can be more difficult to
weave than round strands due to required orientation of the
flattened strands during weaving.
Woven Wall Structure
[0186] The woven wall structures shown in the embodiments shown in
the following figures, FIGS. 14, 15, 16A-C, 17A-C, 18A and 18B
apply to a vascular tubular member 83 that can be implanted as a
surgical vascular graft, as an intravascular tubular member 85
without a folded tubular section 125, as an intravascular folded
tubular member including a folded tubular section 125, or as any
other vascular tubular member. The intravascular tubular member can
be a straight intravascular folded tubular member 95, a bifurcated
intravascular folded tubular member 260, or a straight
intravascular tubular member, without a folded tubular section 125
or a bifurcated intravascular tubular member without a folded
tubular section 125. The woven tubular structures of the present
invention are intended to be formed without a seam and are
therefore seamless. It is further understood that a woven material
of the wall structure described in this invention could be formed
of a flat woven wall structure that is then formed into a straight
or bifurcated tube with a wall structure as described. These
figures are intended to represent various combinations of
multifilament strands 510 and monofilament strands 500 of metallic
material or polymeric material with a straight or curved
conformation used to form the wall structure of the present
vascular tubular member 83. The actual woven structures showing
woven strands of various types is shown in FIGS. 13A-13M. It is
further noted that the circumferentially oriented strands actually
are woven with a helical wind as discussed earlier. This helical
wind can be gradual so that it appears as a generally
circumferentially wound strand as shown in these figures. It is
understood that the circumferential strands 465 or
circumferentially oriented strands can have a significant helical
wind to them. This significant helical wind is accomplished by
winding more than one strand or several strands in the
circumferential direction 470 at the same time. An even greater
helical wind can be accomplished in the circumferential direction
by generating a double helical wind with each helix involving
several strands. A double helix can be formed, for example by
introducing circumferential strands into the tubular weave from two
positions located 180 degrees apart. Axial strands tend to orient
themselves such that they are perpendicular to the
circumferentially oriented strands giving the axial strands a
helical wind or turn to them.
[0187] The present invention for a vascular tubular member 83
includes the wall structure for the vascular tubular member. The
woven wall structures shown in FIGS. 14, 16A-16C, 17A-17C, 18A,
18B, 20A-20D, 21, 22A, 22B, and 23 are included in the preferred
embodiments of this invention. The strands that are of a polymeric
material used to form these wall structures are woven with only
multifilament strands 510 of polymer material. Polymer material can
be any of the polymers indicated including ePTFE, polyester, or
other suitable polymer material. The multifilament strands 510 can
be woven in either a generally axial direction 398 or a generally
circumferential direction 470. These multifilament strands of
polymeric material can be formed of filaments 483 that are either
curved filaments or straight filaments; and hence the multifilament
strands 510 of polymeric material will be referred to as curved
axial polymeric strands 625, curved circumferential polymeric
strands 630, straight axial polymeric strands 635, and straight
circumferential polymeric strands 640. The present invention for a
vascular tubular member 83 includes a wall structure that can be
formed from woven metallic strands 600. The metallic strands 600
can be metallic monofilament strands 490 or metallic multifilament
strands 510. In the preferred embodiments of the above indicated
figures, FIGS. 14, 16A-16C, 17A-17C, 18A, 18B, 19, 20A-20D, 21,
22A, 22B, and 23, the metallic strands are metallic monofilament
strands 490 woven along with the multifilament strands 510 of
polymeric material in either the axial direction 398,
circumferential direction 470, or both directions forming
monofilament strands 490 of metallic material. The monofilament
strands 490 of metallic material can be formed of straight
monofilament strands 605 or curved monofilament strands 615 and
hence the monofilament strands 490 of metallic material will be
referred to as curved axial metallic strands 645, curved
circumferential metallic strands 650, straight axial metallic
strands 655, and straight circumferential metallic strands 660.
[0188] The wall structures described in FIGS. 14, 16A-16C, 17A-17C,
18A, 18B, and 19 can all be applied as a vascular tubular member 83
that is suitable for vascular surgery, as an intravascular tubular
member 85 that is suitable for intravascular implant either with
percutaneous access or with a small surgical cutdown in an
adjoining vessel either proximal or distal to the site of vascular
injury. As an intravascular tubular member 85, it can be used
without an attachment means as shown in these drawings, or it can
be used with any attachment means found in the prior art, or with
the attachment anchor 245 disclosed earlier in this disclosure as a
part of this invention. The wall structures can be formed into a
straight intravascular folded tubular member 95, or a bifurcated
intravascular folded tubular member 260 as shown in FIGS. 2A, 2B,
4A, and 4B. Each vascular tubular member presented has an inlet end
145, an outlet end 148, an inner surface 135, an outer surface 140,
a vascular tubular member wall 662, and a wall thickness 663.
[0189] FIG. 14 shows an embodiment for the wall structure for the
surgical vascular graft, the intravascular tubular member 85, or
the vascular tubular member 83 of this invention. All reference
numerals correspond to those elements previously or otherwise
described. This structure has straight axial metallic strand 655
and straight circumferential metallic strands 660 woven along with
straight axial polymeric strands 635 and straight circumferential
polymeric strands 640. The straight axial polymeric strands 635 or
straight circumferential polymeric strands 640 tend to seal polymer
to polymer crossover points 665 between these strands and can
effectively seal polymer to metal crossover points 670 such as
between a straight axial polymeric strand 635 with a straight
circumferential metallic strand 660. The straight circumferential
metallic strands 660 provide outward force of this tubular member
against the aortic wall in it deployed state. The straight
circumferential metallic strands 660 help to resist kinking by
helping to maintain a round cross section. The straight axial
metallic strands 655 provide the tubular member with strength in
the axial direction 398 to overcome compressive forces that may act
to reduce its axial length. The straight axial metallic strands 655
enhance the ability of the folded tubular section 125 of a straight
95 or bifurcated 260 intravascular folded tubular member to unfold
easily without wrinkling of the folded tubular section center wall
160. The presence of the straight axial metallic strands 655
generates axial stiffness in the tubular member causing it to be
less flexible in negotiating tortuous turns found in the iliac,
femoral, and other arteries of the body.
[0190] FIGS. 14 and 13J show a metal to metal crossover point 610
of a straight circumferential metallic strand 660 with a straight
axial metallic strand 655. FIGS. 14 and 13J will be used as an
example to describe the process of forming a double weave. It is
understood that the double weave can be equally well applied to any
wall structure that involves a metallic strand 600 crossing over
another metallic strand 600. To prevent leakage from occurring at
gaps or leakage sites 495 of such metal to metal crossover points
610 a tubular double weave is created as shown in FIG. 15. For
example, in the axial direction 398 both the straight axial
polymeric strands 635 and the straight axial metallic strands 655
are woven together in the weave plane 675 to the left of the metal
to metal crossover point 610. Near the metal to metal crossover
point 610 the straight axial metallic strands 655 are brought out
of the weave plane 675 and above the straight circumferential
metallic strand 660 and back into the weave plane 675 to the right
of the metal to metal crossover point 610. Underneath the straight
axial metallic strands 655 at the crossover point the straight
axial polymeric strands 635 are woven with the straight
circumferential polymeric strands 640 and the straight
circumferential metallic strand 660 such that a continuous woven
layer 680 is located beneath the straight axial metallic strand 655
that was brought out of the weave plane 675. The result is a leak
free wall structure with metallic strands being woven in two
directions, axial direction 398 and circumferential direction
470.
[0191] FIG. 16A shows another embodiment for the wall structure of
the present invention. In this embodiment straight circumferential
polymeric strands 640 and straight circumferential metallic strands
660 are woven circumferentially and only straight axial polymeric
strands 635 are woven axially. This embodiment does not have the
axial compressive force capability described in the embodiment of
FIG. 14 but it has excellent kink resistance due to the straight
circumferential metallic strands 660 and has excellent flexibility
through tortuous turns since only the flexible polymeric strands
are positioned axially.
[0192] FIG. 16B shows still another vascular tubular member wall
structure with a curved axial metallic strand 645 woven along with
a straight axial polymeric strand 635 in the axial direction 398
instead of the straight axial metallic strand 655 as shown in FIG.
14. The curved axial metallic strand 645 also provides the vascular
graft, the intravascular graft, or the tubular member with good
axial support against compressive forces generated by the thrombus
60 and other physiological forces that can be placed upon the
tubular member. The curved axial metallic strand 645 can compress
elastically and thereby will provide this tubular member wall
structure with good axial flexibility to extend around tortuous
turns in a blood vessel. The curved axial metallic strand 645
provides a benefit to the folded tubular section 125 of a straight
intravascular folded tubular member 95 or bifurcated intravascular
folded tubular member 260 by resisting wrinkling during the
unfolding process. The curved axial metallic strand 645 can prevent
the center wall of the folded tubular section 125 from forming
wrinkles (see FIG. 7E) and can help the intravascular folded
tubular section 125 to unfold evenly during the deployment of the
folded tubular member.
[0193] FIG. 16C shows yet another wall structure for the surgical
vascular graft, intravascular tubular member 85, or vascular
tubular member 83 having a similar structure to that of FIG. 16B
only with a curved circumferential metallic strand 650 in the
circumferential direction instead of the straight circumferential
metallic strand 660. The axial strands 475 have remained the same
as in FIG. 16B. The curved circumferential metallic strand 650
found in this structure allows the folded tubular section 125 of a
straight intravascular folded tubular member 95 or bifurcated
intravascular folded tubular member 260 to unfold with greater ease
due to their ability to elongate diametrically as one curved
circumferential metallic strand 650 located in an folded tubular
section inner wall 165 or folded tubular section outer wall 155
passes adjacent to another curved circumferential metallic strand
650 located in the folded tubular section center wall 160. The
curves or bends in the curved circumferential metallic strands 650
also allows the intravascular folded tubular member to expand out
uniformly to its deployed diameter 237 and provide uniform contact
with the wall or the native vessel or aortic wall in the case of
abdominal aortic aneurysm. The deployed diameter 237 of the
vascular tubular member 83 used as an intravascular tubular member
85 (see FIG. 1B) of the present invention can be smaller than the
equilibrium diameter that the intravascular tubular member could
attain if not constrained by the native vessel in the deployed
state.
[0194] FIG. 17A shows one more vascular tubular member 83 wall
structure with a curved circumferential polymeric strand 630 woven
along with a straight circumferential metallic strand 660 in the
circumferential direction and a straight axial polymeric strand 635
is woven along with a curved axial metallic strand 645 in the axial
direction 398. The curved circumferential polymeric strand 630
provides an amount of circumferential stretch in the diametric
direction. The straight circumferential metallic strands 660 and
curved axial metallic strands 645 restrict excessive
circumferential stretch of the curved circumferential polymeric
strands 630. This wall structure can also be modified slightly to
provide an additional characteristic. Near the inlet portion 685 of
the tubular means the straight circumferential metallic strand 660
can be eliminated thereby allowing the vascular tubular member to
expand to a larger circumference. This circumferential expansion
allows the vascular tubular member of the present invention to
accommodate a reasonable tolerance in the estimated diameter of the
artery such as an estimation of the diameter of the aortic neck.
The inlet end 145 of the vascular tubular member 83 can accommodate
a tolerance in the estimation of the aortic neck diameter and
provide a leak free seal of the vascular tubular member with the
vessel wall without overlap of excess material at the inlet end 145
or outlet end 148 due to an oversized diameter of the vascular
tubular member 83. Similar circumferential accommodation also
applies to accommodating the estimated diameter of an artery or
blood vessel such as the iliac or femoral artery with the outlet
end 148 of the vascular tubular member 83.
[0195] Accommodation of the estimated aortic diameter or other
blood vessel diameter with a vascular tubular member 83 of a fixed
non-flexible wall material in the circumferential direction 470
with a maximum diameter can also be accomplished by ensuring that
the vascular tubular member chosen can expand to a larger maximum
deployed diameter 237 than the arterial diameter in which the
device is to be placed. For the abdominal aortic aneurysm
application this is accomplished by choosing a vascular tubular
member 83 with an equilibrium diameter or maximum dimension of the
deployed diameter 237 that is larger than the aortic diameter plus
any tolerance in diameter estimation associated with measuring
technique errors. Any excess intravascular tubular member wall
material due to a slight oversized tubular member diameter will
result in an overlap of excess wall material. Provided that this
overlap material is held tightly against the aortic wall by the
proximal attachment means 87, leakage at the proximal site will not
occur.
[0196] FIG. 17B shows yet one more vascular tubular member wall
structure which is the same as that of FIG. 17A except that a
curved circumferential metallic strand 650 has replaced the
straight circumferential metallic strand 660. This structure offers
the ability to stretch in the circumferential direction 470 to a
limited extent controlled by the amount of curvature provided to
the curved circumferential metallic strands 650 and curved
circumferential polymeric strands 630. This vascular tubular member
83 wall structure provides good anti-kink characteristics, good
axial support against compression, good flexibility, and will
accommodate a reasonable tolerance in the diameter of the proximal
aortic neck, and a tolerance on the iliac artery diameter.
[0197] FIG. 17C shows still one more vascular tubular member wall
structure with a curved circumferential polymeric strand 630, a
curved circumferential metallic strand 650, a curved axial
polymeric strand 625 interwoven, and a curved axial metallic strand
645. This structure offers the ability to stretch in the
circumferential direction 470 and axial direction 398 to a limited
extent controlled by the amount of curvature provided to the
strands. This structure can extend throughout the entire tubular
means. This vascular tubular member wall structure provides good
anti-kink characteristics, good axial support against compression,
good flexibility, and will accommodate a reasonable tolerance in
the aortic neck diameter, and a tolerance on the iliac artery
diameter.
[0198] FIGS. 18A and 18B show further embodiments of the wall
structure that can be applied to the vascular tubular member 83 of
the present invention. The vascular tubular member wall structures
presented in FIGS. 14, 16A-16C, 17A-17C that contain curved axial
metallic strands 645 or straight axial metallic strands 655 which
can be directed with an augmented amount of helical turn. This
augmented helical turn is accomplished by taking the straight axial
metallic strands 655 out of the weave plane 675, creating a
step-over 690 by stepping the straight axial metallic strands 655
over to a new site that is displaced circumferentially, and
inserting the strands 655 back into the plane of the weave 675 as
shown in FIG. 18A. This stepping over process allows the axial
metallic strand 655 to assume a helical pathway along the axial
direction 398 of the vascular tubular member 83. This augmented
amount of helical turn is in addition to the gradual helical turn
naturally found in the axially oriented metallic strands 600 due to
their natural desire to orient perpendicular to the generally
circumferential strands 465 such as the straight circumferential
metallic strands 660 and curved circumferential polymeric strands
630 which also have a slight helical turn since they are wound in a
continuous helix as shown in FIG. 18A. The augmented helical turn
of the metallic strand in the generally axial direction 398
provides the stent-graft with an ability to bend without kinking
even when straight metallic strands are used in the axial direction
398. In FIG. 18B two straight circumferential metallic strands 660
are wound in a double helix with a greater angle with respect to
the circumference. This induces the curved axial metallic strands
645 to orient at an angle with respect to the axial direction
480.
[0199] In the embodiments of the wall structure of the present
invention shown in FIGS. 18A and 18B curved circumferential
polymeric strands 630 and curved axial polymeric strands 625 are
wound in the circumferential 470 and axial direction 398 to provide
the vascular tubular member 83 with a supple feel and good bending
characteristics without kinking. For simplicity of manufacturing, a
straight circumferential metallic strand 660 is wound in the
circumferential direction 470. Either a curved axial metallic
strand 645 (see FIG. 18B) or a straight axial metallic strand 655
(see FIG. 18A) with the step over characteristic described above is
used in the axial direction 398 to provide the necessary
compressive strength as well as provide good flexibility to the
vascular tubular member 83.
[0200] An entire straight vascular tubular member or bifurcated
vascular tubular member can be formed from a single contiguous
woven material comprised of the polymeric multifilament strands 510
or the combined polymeric multifilament strands 510 and metallic
monofilament strands 490 described in FIGS. 14, 16A-16C, 17A-17C,
18A, and 18B. The bifurcated intravascular folded tubular member
260 can be woven without seam in its proximal tubular section,
folded tubular section 125, or distal tubular section 130. This is
accomplished by weaving the main trunk 270 with approximately twice
the number of polymeric multifilament strands 510 and metallic
monofilament strands 490 in the axial 398 and circumferential 470
directions as will be used in each proximal leg tube 275, folded
tubular section 125, or distal tubular section 130 (see FIGS. 13J
and 14). The weaving of two proximal leg tubes 275 from the main
trunk 270 can proceed continuously without seam as approximately
half of the strands in the axial direction 398 and circumferential
direction 470 are directed from the main trunk 270 to each proximal
leg tube. The weave plane 675 for each proximal leg tube 275 (see
FIG. 4A) is continued to form the weave plane 675 for the wall
structure for the folded tubular section 125 and the distal tubular
section 130. The wall thickness 663 of the woven vascular tubular
member 460 (see FIG. 13A) can be formed to minimal wall thickness
663 while maintaining strength of the vascular tubular member wall
662.
Braided Wall Structure
[0201] FIG. 19 shows a wall structure of the braided vascular
tubular member 705 of the present invention formed from a braiding
process with similar nomenclature being used as used for the woven
vascular tubular member 460. The braided vascular tubular member
705 has straight polymeric and straight metallic strands braided in
a right hand spiral forming a straight right spiral polymeric
strand 710 and a straight right spiral metallic strand 715, and in
a left hand spiral forming a straight left spiral polymeric strand
720 and a straight left spiral metallic strand 725. The braiding
process provides some ability for this wall structure to
accommodate reasonable tolerances in the estimation of the proximal
aortic neck diameter in order to provide a good diametric fit
between the braided vascular tubular member 705 and the proximal
aortic neck. The strands 710, 715, 720, and 725 can be made with
localized bends or curves in them as described earlier, and these
strands can be braided as described for the embodiments of FIGS.
14, 16A-16C, 17A-17C, 18A, and 18B, and these stands can be braided
as described in FIG. 19. The presence of the straight or curved
metallic monofilament strands 605 and 615 (see FIGS. 13L and 13K)
provides good axial and circumferential strength and stability
against compression in the radial or axial direction 398. The
metallic curved monofilament strands 615 or curved polymeric
multifilament strands 573 can provide the vascular tubular member
with a greater flexibility due to the ability of these strands to
compress or extend as the braided vascular tubular member 705 is
exposed to a tortuous pathway. The spacing between the right spiral
metallic strands 715 or the left spiral metallic strands 725
braided in either the right or left spiral to form a braided
vascular tubular member 705 is similar to the spacing ranges stated
for the woven vascular tubular member 460.
Applications of Wall Structure
[0202] The wall structure described in FIGS. 13A-13M, 14, 15,
16A-16C, 17A-17C, 18A, 18B, and 19 can be applied to a surgical
vascular graft, an intravascular tubular member 85, or other
vascular tubular member 83. As a surgical vascular graft with a
woven or braided wall structure, the metallic straight 605 and
curved 615 monofilament strands offer improved kink resistance and
can provide crush resistance to the vascular graft when placing the
graft across a knee joint or other vascular space that is exposed
to compressive forces. For the woven vascular tubular member 460
the curved circumferential polymeric strands 630 and curved
circumferential metallic strands 650 offer enhanced diametric
flexibility or diametric compliance which can lead to improved
healing at anastomoses of the vascular tubular member with the
native vessel. The curved axial metallic strands 645 or straight
axial metallic strands 655 of the woven tubular member offer
resistance to axial compressive forces which can also lead to
kinking and allow the vascular graft to be pulled through tunnels
during implantation without concern for damage to the vascular
graft due to excessive axial stretching. As an intravascular
tubular member the woven and braided wall structures offer the
benefit of a built-in stent. For the woven vascular tubular member
460 the straight circumferential metallic strands 660 and curved
circumferential metallic strands 650 offer a thin wall structure
with excellent expansion elastic forces acting outward against the
native vessel wall or native lumen. Since the straight 660 and
curved 650 circumferential metallic strands can be positioned
regularly within the wall structure throughout the weave, there can
be more of them and their diameter can be smaller than stent wires
for most prior art stents. For the woven vascular tubular members
460 the straight 660 and curved 650 circumferential metallic
strands are nearly circumferential; they exert a greater outward
force for a thinner strand diameter than a zig zag shaped stent or
as stent with large bends that require their struts 370 to extend
in a non-circumferential direction. The straight 655 and curved 645
axial metallic strands of the woven vascular tubular members 460
also provide a built-in structure onto which any attachment means
can be attached firmly to either the inlet 145 or outlet end 148.
The woven wall structures with curved circumferential metallic
strands 650 and curved circumferential polymeric strands 630 are
able to stretch circumferentially and accommodate errors in
estimated diameter of the native blood vessel. The woven wall
structures with curved circumferential polymeric strands 630 along
with straight or curved circumferential metallic strands 650 can
also accommodate errors in the estimation of native vessel diameter
by removing the straight 660 or curved 650 circumferential metallic
strands near the inlet end 145 or the outlet end 148 of the
intravascular tubular member. The curved circumferential polymeric
strands 630 of the woven wall structure will allow the
intravascular tubular member 85 to stretch and accommodate errors
in the diameter estimation such that any attachment means 87 placed
at the inlet end 145 or outlet end 148 can form a leak tight seal
with the artery either proximal or distal to the vessel injury. The
woven 460 or braided 705 vascular tubular member formed from
polymeric multifilament strands 510 can also be used as an
intravascular tubular member 85 and offers the strongest and safest
wall structure for the thinnest wall thickness 663. The safety
associated with weaving or braiding multifilament strands 510 of
ePTFE relates to its ability to avoid a catastrophic tear in the
wall structure. Standard tubular ePTFE vascular grafts can form an
axial or circumferential tear that can lead to significant
complications or possibly patient death. The woven vascular tubular
member 460 formed from multifilament strands 510 of ePTFE would not
allow a local defect found in the wall structure to extend in an
axial direction 398 or circumferential direction 470. The
multifilament strands allows the woven vascular tubular member 460
formed from the strands containing ePTFE filaments 525 to seal
against blood leakage at crossover points 485 of the ePTFE
strands.
[0203] The wall structure described in FIGS. 13A-13E, 14, 15,
16A-16C, 17A-17C, 18A, and 18B are well suited to the straight
intravascular folded tubular member 95 and bifurcated intravascular
folded tubular member 260 with associated advantages. The woven
wall structure, woven from polymeric multifilament strands 510 in
one embodiment and in other embodiments with metallic straight 605
or curved 615 monofilament strands also woven along with the
polymeric multifilament strands 510, offers the greatest strength
with one of the thinnest wall thicknesses 663. Since the folded
tubular section 125 of the straight intravascular folded tubular
member 95 or bifurcated intravascular folded tubular member 260 has
three folded tubular section walls 330, it is important that each
wall be of a minimum wall thickness 663. Also of importance is
ensuring that the straight or bifurcated proximal tubular section
wall 170, folded tubular section walls 330, and distal tubular
section wall 190 cannot be easily torn which can lead to a life
threatening sequalae for the patient. These safety and performance
characteristics can be obtained by weaving multifilament strands
510 of ePTFE or multifilament strands 510 of polyester as described
in FIGS. 13A-13M. The folded tubular section 125 requires that the
folded tubular section inner wall 165, folded tubular section outer
wall 155, and folded tubular section center wall 160 can slide with
respect to each other as the straight intravascular folded tubular
member 95 or bifurcated intravascular folded tubular member 260 is
deployed from a partially deployed state of smaller length to a
fully deployed state of greater length. The woven wall structures
with straight circumferential metallic strands 660 or curved
circumferential metallic strands 650 provide a substantially smooth
wall structure without significant protrusions that can provide
ease of unfolding in the folded tubular section 125. The weaving of
metallic straight 605 or curved 615 monofilament strands in the
circumferential direction 470 into the wall structure provides an
optimum way of providing a built-in metallic stent to provide
outward expansion forces while minimizing the thickness of the
three folded tubular section walls 330. Since the metallic straight
605 or curved 615 monofilament strands are acting in a nearly
circumferential direction 470, their strength to provide the
outward expansion forces is greatest for the least metallic strand
600 diameter.
[0204] FIG. 20 shows the inlet end 145 and outlet end 148 of an
intravascular tubular member 85 with a wall structure similar to an
embodiment shown in FIG. 14, 16A-16C, 17A-17C, 18A, or 18B. The
woven wall structure can be formed of any combination of weave
involving either straight multifilament strands, straight
monofilament strands, curved multifilament strands, or curved
monofilament strands used to weave generally circumferential
polymeric strands 740, generally circumferential metallic strands
745, generally axial polymeric strands 750, and generally axial
metallic strands 755 as described in the previous embodiments or
otherwise intended. Thus for example, a generally circumferential
polymeric strand 740 is understood to mean a straight 640 or curved
630 circumferential polymeric strand, a generally circumferential
metallic strand 745 means a straight 660 or curved 650
circumferential metallic strand, a generally axial polymeric strand
750 means a straight 635 or a curved 625 axial polymeric strand,
and a generally axial metallic strand 755 means a straight 655 or a
curved 645 axial metallic strand. This definition shall also be
applicable to FIGS. 21-23. Attached to the inlet end 145 is an
attachment means 87. The attachment means can be the attachment
anchor 245 described in FIGS. 9A, 9B, 10A-10C, and 11A-11D. A
displaced attachment anchor 760 is located at a position displaced
away from the inlet end 145 in a proximal direction and not in
contact with the woven wall structure. The displaced attachment
anchor 760 is the attachment anchor 245 that is located away from
the inlet end 145. The distance that the displaced attachment
anchor is located from the inlet end 145 can range from
approximately 5 millimeters to 40 millimeters. For an abdominal
aortic aneurysm application the displaced attachment anchor 760 can
be displaced approximately 10 to 25 millimeters away from the inlet
end 145. The displaced anchor is attached to the intravascular
tubular member with axially oriented attachment strands 765. The
attachment strands 765 can be attached to the displaced attachment
anchor 760 through selected intranodal openings 385 (see FIG. 9A)
of the displaced attachment anchor 760. The attachment strands 765
can be extensions of the generally axial metallic strands 755 or
generally axial polymeric strands 750. Preferably the attachment
strands 765 are generally axial metallic strands 755 which are
continuous with the generally axial metallic strands 755 found in
the weave of the intravascular tubular member 85. Thus, the woven
wall structure of the intravascular tubular member 85 with
generally axial metallic strands 755 has the structure inherent in
the woven intravascular tubular member to simply extend some or all
of the generally axial metallic strands 755 proximally beyond the
inlet end 145 and use them to attach to the displaced attachment
anchor 760. The displaced attachment anchor 760 provides a proximal
anchoring site that is positioned farther away proximally from the
vessel injury than the inlet end 145. Vessel side branches such as
the left renal artery 45 and right renal artery 50 in the case of
abdominal aortic aneurysm that can extend from the aorta adjacent
and proximal to the inlet end 145 of the intravascular tubular
member 85 are able to receive blood flow from the native vessel
between the inlet end 145 or the intravascular tubular member and
the displaced attachment anchor 760. In the case of treating
abdominal aortic aneurysm the right and left renal arteries 45
& 50 can be located between the displaced attachment anchor 760
and the inlet end 145 of the vascular tubular member. Only a
minimal number of attachment strands 765 are needed to attach the
displaced attachment anchor 760 to the inlet end 145 of the tubular
member, ranging from two to approximately sixteen. Preferably the
number of attachment strands 765 ranges from approximately three to
six. The likelihood of an attachment strand crossing over a vessel
side branch is reduced with a smaller number of attachment strands
765. A single attachment strand 765 extending from a generally
axial metallic strand 755 that crosses over an inlet to a vessel
branch will not significantly affect the flow rate of blood to that
side branch vessel. The displaced attachment anchor 760 can have
barbs 250 to help provide a more firm attachment to the vessel wall
such as the vessel wall of the aorta. Either the displaced anchor
760 or the attachment anchor 245 attached at or near the inlet end
145 of the tubular member can have barbs 250 or can be provided
without barbs 250.
[0205] The attachment anchor 245 positioned at the inlet end 145 or
outlet end 148 of the intravascular tubular member can also be
efficiently attached to any generally axial metallic strands 755 or
generally axial polymeric strands 750 of the wall structure
described in FIG. 14, 16A-16C, 17A-17C, 18A, 18B, or 20. Preferably
the attachment anchor 245 is attached to a plurality of generally
axial metallic strands 755 that can form a firm attachment to the
attachment anchor 245. The general axial metallic strands 755 can
efficiently attach to the attachment anchor 245 using the
intranodal openings 385 as sites for attachment. A generally
circumferential metallic strand 745 near the inlet end 145 or
outlet end 148 of the vascular tubular member can be removed to
provide the intravascular tubular member 85 formed with curved
circumferential polymeric strands 630 with stretchability with an
ability to accommodate error in the estimated diameter of the
native vessel as was discussed in FIG. 17A. This wall structure
allows the inlet end 145 or outlet end 148 to stretch and enlarge
in diameter by up to approximately fifty percent and provide a
better diametrical fit to the native vessel without leakage. The
attachment anchor 245 attached to the stretchable inlet end 145 or
outlet end 148 of the intravascular tubular member can make a
tighter seal with the native vessel wall without requiring overlap
of the wall structure near the inlet end 145 or outlet end 148
between the attachment anchor 245 and the native vessel wall or
native lumen. The braided wall structure of the vascular tubular
member shown in FIG. 19 can also be used with the displaced
attachment anchor 760. A plurality of right spiral metallic strands
715 or left spiral metallic strands 725 can be extended proximally
beyond the inlet end 145 and attached to the displaced attachment
anchor 760 in a manner similar to that described for the woven
vascular tubular member 460.
[0206] FIG. 21 shows a vascular tubular member 83 with a folded
tubular section 125 and with a woven wall structure as described in
FIGS. 14, 16A-16C, 17A-17C, 18A, and 18B. The woven wall structure
can be formed from generally circumferential metallic strands 745,
generally circumferential polymeric strands 740, generally axial
metallic strands 755 and generally axial polymeric strands 750 that
have been defined in the description of FIG. 20. The woven
structure containing metallic monofilament strands 490 and
polymeric multifilament strands 510 is well suited to forming the
folded tubular section 125 of the straight intravascular folded
tubular member 95 or the bifurcated intravascular folded tubular
member 260. The folded tubular section 125 can be formed with a
minimal triple wall thickness 770 for the folded tubular section
walls 330 due to the wall structure of the present invention.
Having the generally axial metallic strands 755 and generally
circumferential metallic strands 745 woven into the wall provides
the present invention with the advantage that a greater number of
smaller thickness metallic strands 600 can be used to provide the
outward force generated by the generally circumferential metallic
strands 745. Also the generally circumferential metallic strands
745 and generally axial metallic strands 755 do not require an
additional binding means to bind them to the vascular tubular
member 83 as required by other prior art devices. Providing the
general circumferential metallic strands 745 as part of the weave
also allows the folded tubular section 125 to unfold smoothly and
evenly without catching or snagging such as on a protruding metal
wire or stents attached to the outside of the walls of other prior
art stent-graft devices. The woven wall structure of the present
invention will allow the folded tubular section 125 to unfold with
a steady uniform force as the intravascular folded tubular member
extends in length from a partially deployed state to a deployed
state. It is understood that the woven structure described in this
invention can be applied to straight intravascular folded tubular
member 95 or bifurcated intravascular folded tubular member 260. In
addition, the woven structure can be applied to the straight
intravascular folded tubular member 95 or the bifurcated
intravascular folded tubular member 260 that do not contain a
folded tubular section 125 and are intended for intravascular use.
Also, the woven wall structure can be applied to straight or
bifurcated vascular tubular members 83 that can be used for
standard surgical implant for treatment of vascular injuries. The
straight 95 or bifurcated 260 intravascular folded tubular member
is also well suited to be formed entirely from only generally
circumferential polymeric strands 740 and generally axial polymeric
strands 750 as shown in FIG. 22. The thin wall thickness 663
provides the folded tubular section walls 330 with a thin overall
wall thickness for the three walls. The smooth wall structure
formed from the woven polymeric multifilament strands 510 will
allow for smooth and uniform unfolding of the folded tubular
section 125 without binding as it unfolds during deployment to a
fully deployed state. All reference numerals correspond to those
elements previously or otherwise described. The woven vascular
tubular member 460 shown in FIGS. 14, 16A-C, 17A-C, 18A, and 18B
are well suited to forming a straight 95 or bifurcated 260
intravascular folded tubular member. In placing the outlet end 148
in its appropriate position it is important that the woven vascular
tubular member 460 does not reduce in diameter as the outlet end
148 is being placed and the folded tubular section 125 is
unfolding. The woven vascular tubular member 460 does not reduce in
diameter if it is pulled from each end in tension. The woven
vascular tubular member 460 does not reduce in diameter when used
as a straight 95 or bifurcated 260 intravascular folded tubular
member that is being extended in length and forms a fully deployed
state. The presence of straight 660 or curved 650 circumferential
metallic strands further helps to maintain the deployed diameter
237 at a constant value without necking down or reducing in
diameter in extending to a fully deployed state. The woven wall
structure is also well suited to the straight 95 or bifurcated 260
intravascular folded tubular member because the axial strands 475
provide a significant resistance to axial length change in the
material itself. Thus during deployment from a partially deployed
state to a fully deployed state the extension to a deployed tubular
member length will occur primarily due to the unfolding of the
folded tubular section 125.
[0207] FIG. 23 shows a bifurcated intravascular folded tubular
member 260 formed with a woven wall structure. The woven wall
structure can be formed from generally circumferential metallic
strands 745, generally circumferential polymeric strands 740,
generally axial metallic strands 755 and generally axial polymeric
strands 750 that have been defined in the description of FIG. 20.
The folded tubular sections 125 are formed from the woven wall
structure. The inlet end 145 has an attachment anchor 245 attached,
the attachment anchor 245 having barbs 250. Each outlet end 148 has
an attachment anchor 245 attached, each attachment anchor 245 at
the outlet end 148 being without barbs 250. As shown in FIG. 23,
this bifurcated intravascular folded tubular member 260 is intended
as an intravascular tubular member 85 that is delivered to the site
of a vascular injury through a proximal or distal vessel adjacent
to and connecting to the injured vessel. One common application for
this intravascular tubular member is for the treatment of abdominal
aortic aneurysm. For this application, the tubular member is
generally delivered through a smaller diameter delivery sheath 225
(see FIG. 4C) that is capable of being introduced into one of the
common femoral arteries 30. Typically, a small surgical cutdown may
be required to access the femoral artery and provide access for a
delivery sheath 225 through which the bifurcated intravascular
folded tubular member 260 is delivered. The common femoral artery
30 which provides the main access for the intravascular tubular
member 85 including the access for the inlet end 145 of the
intravascular tubular member 85 will be referred to as the
ipsilateral artery or the ipsilateral side. The intravascular
tubular member 85 is delivered to the injury site in a nondeployed
state, with a smaller bifurcated nondeployed inlet end diameter 230
and nondeployed outlet end diameter 235, and a shorter bifurcated
nondeployed tubular member length 280 (see FIG. 4B). The bifurcated
intravascular folded tubular member 260 is preferred to have an
attachment anchor 245 at the inlet end 145 of the intravascular
tubular member to ensure a tight and leak free fit with the aorta
in a deployed state although the attachment anchor 245 is not
required of the present invention. It is understood that the
bifurcated intravascular folded tubular member 260 can have
generally circumferential metallic strands 745 woven within the
wall structure of the tubular member. Therefore, it is not a
requirement that the bifurcated intravascular folded tubular member
260 of the present invention have an attachment anchor 245 at the
inlet end 145 or at the outlet end 148. It is preferred to have an
attachment anchor 245 at the inlet end 145 to better and more
firmly attach the intravascular folded tubular member to the blood
vessel wall proximal to the vessel injury without blood leakage at
that site or migration of the intravascular folded tubular member.
The bifurcated intravascular folded tubular member 260 can be a
self-expandable tubular member that is contained within the smaller
diameter tubular delivery sheath 225 (see. FIGS. 4C and 4D) for
delivery and assist in deployment. Upon removal of the
intravascular tubular member from the delivery sheath 225, the
bifurcated intravascular folded tubular member 260 and each
attachment anchor 245 is capable of expanding outward and can exert
an outward force against the aortic or other arterial wall. The
bifurcated intravascular folded tubular member 260 can also be a
balloon-expandable tubular member that can be delivered to the site
of vessel injury mounted on a balloon catheter. Either the folded
tubular member 125, each attachment anchor 245, or both the folded
tubular member 125 and the attachment anchors 245 can require
expansion from a dilitation balloon to force them outward and into
close approximation with the aorta, the wall of the native lumen,
or to a radially deployed inlet end diameter 105 and deployed
attachment anchor diameter 320. Whether the intravascular tubular
member and attachment anchor 245 are self-expandable or
balloon-expandable, the attachment anchor 245 located at the inlet
end 145 of the tubular member is carefully placed such that it is
positioned adjacent and just distal to the renal arteries or within
the proximal aortic neck 90 prior to deployment (see FIG. 1B). For
treatment of abdominal aortic aneurysm the short axial length of
the attachment anchor 245, along with the understanding that the
attachment anchor 245 is formed of a metal such as tantalum or
contains metal that can be easily visualized under fluoroscopy,
allows the attachment anchor 245 to be positioned accurately and
close to the renal arteries. Barbs 250 can be located on the
attachment anchor 245 to ensure that the attachment anchor 245 is
well seated into the aorta and cannot migrate distally although
they are not required for all embodiments of this invention. It is
further understood that a displaced attachment anchor 760 can also
be located proximal to the renal arteries and attached to the
bifurcated intravascular folded tubular member 260 using attachment
strands 765 as described earlier.
[0208] After the inlet end 145 of the bifurcated intravascular
folded tubular member 260 has been deployed and attached to the
aorta for the case of abdominal aortic aneurysm repair with the
attachment anchor 245, each outlet end 148 of the tubular member is
moved into its appropriate location within the iliac 20 & 25 or
femoral 30 artery. As the outlet ends 148 of the bifurcated tubular
member are moved to their appropriate location, the folded tubular
sections 125 of each leg can be unfolded to allow the distal
tubular section 130 and bifurcated proximal tubular section 265 to
extend in length. An attachment anchor 245 can be located at each
outlet end 148 although it is not required for the present
invention to have any such attachment anchor 245. The attachment
anchor 245 located at each outlet end 148 of the bifurcated
intravascular folded tubular member 260 can be of a self-expandable
or balloon-expandable nature as described earlier for the
attachment anchor 245 that can be located at the inlet end 145. The
attachment anchor 245 at each outlet end 148 is then expanded or
allowed to expand placing the distal tubular section 130 into close
contact with the wall of the native vessel or the native lumen
wall. The bifurcated intravascular folded tubular member 260 has
then been fully deployed to its radially deployed inlet end
diameter 105 and radially deployed outlet end diameter 110 and to
its bifurcated deployed tubular member length 290 (see FIG. 4B).
Each outlet end 148 can be placed precisely in its desired position
in the iliac or femoral artery while observing or real time
fluoroscopy the placement of each outlet end 148.
[0209] The firm anchoring provided by the attachment anchor 245 of
this invention will ensure that the inlet end 145 of the bifurcated
intravascular folded tubular member 260 will not migrate during the
unfolding of the folded tubular section 125 and after the
bifurcated intravascular folded tubular member 260 is implanted.
The attachment anchor 245 combined with the one-piece construction
provides a leak free seal to completely isolate the aneurysmal
space from the blood flow passage 100 within the bifurcated
intravascular folded tubular member 260. The wall structure allows
a displaced attachment anchor 760 (see FIG. 20) to be attached to
the bifurcated intravascular folded tubular member 260. The
generally axial metallic strands 755 can extend proximally beyond
the inlet end 145 and form a direct attachment to the displaced
attachment anchor 760 (see FIG. 20) by attaching to the intranodal
openings 385. It is understood that a straight intravascular folded
tubular member 95 could have similarly been shown with the woven
wall structure and attachment anchor 245 described in this
embodiment. The present invention is intended to include both
straight 95 and bifurcated 260 intravascular folded tubular member
including all of the features described in this disclosure.
Delivery Procedure
[0210] It is further an additional embodiment of this invention to
provide a bifurcated intravascular folded tubular member 260 that
can be delivered and fully deployed either percutaneously or
through a small surgical cutdown in one common femoral artery 30
and placed within the aorta for treatment of abdominal aortic
aneurysm without the need for access to the contralateral artery
such as the contralateral common femoral artery 30. This can be
accomplished by first delivering the bifurcated intravascular
folded tubular member 260 to the abdominal aorta at the site of the
abdominal aortic aneurysm 5 between the renal arteries and the
aorto-iliac bifurcation 57 (see FIGS. 1A and 1B). After the inlet
end 145 of the bifurcated intravascular folded tubular member 260
has been placed proximal to the aortic injury, the entire
bifurcated intravascular folded tubular member as shown in FIG. 4B,
5, or 23 can be located entirely within the abdominal aorta and
proximal to aorto-iliac bifurcation 57 (see FIG. 1B). One outlet
end 148 of the bifurcated intravascular folded tubular member 260
on the ipsilateral side can be deployed to its appropriate position
in the iliac or femoral artery. The outlet end 148 of the
bifurcated intravascular folded tubular member 260 on the
contralateral side can then be placed into appropriate position
with a contralateral side outlet end placement means. This
contralateral side outlet end placement means is introduced through
the ipsilateral femoral artery and can move the outlet end 148 of
the bifurcated intravascular folded tubular member 260 such that
the folded tubular section 125 can unfold allowing the proximal or
distal section to extend and provide an extension of the tubular
member on the contralateral side so as to place the outlet end 148
in an appropriate position. The attachment anchor 245 located on
the contralateral side is expanded or allowed to expand to hold the
outlet end 148 of the bifurcated intravascular folded tubular
member 260 securely in contact with the arterial wall or the inside
of the vessel lumen.
[0211] The present invention includes a one piece bifurcated
intravascular folded tubular member 260 which is different than the
modular systems described in the prior art for treating abdominal
aortic aneurysm. The one piece construction of the present
invention cannot form leak pathways such as those that occur
between the union of various segments found in modular systems. The
present intravascular tubular member provides a device for treating
vascular injury such as abdominal aortic aneurysm where the axial
length of the native lumen extending through the aortic aneurysm is
very difficult to measure using angiographic means. Estimating the
length angiographically will very often lead to an incorrect
estimation of the length of intravascular graft that is needed. The
result can be the implantation or another prior art stent-graft
device that is too short and does not extend beyond the injured
artery to the region that is not injured or healthy. If the prior
art stent-graft is too long, it can extend beyond an appropriate
point in the iliac or femoral artery and can block a side branch
such as the internal iliac artery 80. With the intravascular
tubular member 85 of the present invention, the length of the
intravascular tubular member 85 or vascular tubular member 83 is
determined in situ or while it is being placed. Therefore, the
intravascular tubular member 85 of the present invention can be
extended precisely to the appropriate length without concern for
the inaccuracies associated with trying to estimate the length of
the tortuous path for the intravascular tubular member.
* * * * *