U.S. patent application number 12/491051 was filed with the patent office on 2010-01-07 for embolic filtering devices for bifurcated vessels.
This patent application is currently assigned to ADVANCED CARDIOVASCULAR SYSTEMS, INC.. Invention is credited to William J. Boyle, ANDY E. DENISON.
Application Number | 20100004673 12/491051 |
Document ID | / |
Family ID | 29778905 |
Filed Date | 2010-01-07 |
United States Patent
Application |
20100004673 |
Kind Code |
A1 |
DENISON; ANDY E. ; et
al. |
January 7, 2010 |
EMBOLIC FILTERING DEVICES FOR BIFURCATED VESSELS
Abstract
An embolic filtering device for use in a bifurcated vessel
includes delivery device having a first guide wire and a second
guide wire. The second guide wire diverges from the distal-end
region of the first guide wire. The filter device also includes a
filter support having a first deployment member and a second
deployment member. These deployment members can be formed as a
first loop and a second loop. A bifurcated filter element is
coupled to the filter support. The distal-end region of the first
guide wire extends through a first leg of the filter element and
the second guide wire extends through a second leg of the filter
element. During use, the first leg of the filter element is
deployed within a first branch of the bifurcated vessel and the
second leg of the filter element is deployed within a second branch
of the bifurcated vessel.
Inventors: |
DENISON; ANDY E.; (Temecula,
CA) ; Boyle; William J.; (Fallbrook, CA) |
Correspondence
Address: |
FULWIDER PATTON, LLP (ABBOTT)
6060 CENTER DRIVE, 10TH FLOOR
LOS ANGELES
CA
90045
US
|
Assignee: |
ADVANCED CARDIOVASCULAR SYSTEMS,
INC.
Santa Clara
CA
|
Family ID: |
29778905 |
Appl. No.: |
12/491051 |
Filed: |
June 24, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11108309 |
Apr 18, 2005 |
7572272 |
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12491051 |
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10180287 |
Jun 26, 2002 |
6887258 |
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11108309 |
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Current U.S.
Class: |
606/200 |
Current CPC
Class: |
A61F 2002/018 20130101;
A61F 2230/001 20130101; A61F 2230/008 20130101; A61F 2/013
20130101; A61F 2002/065 20130101; A61F 2230/0008 20130101 |
Class at
Publication: |
606/200 |
International
Class: |
A61F 2/01 20060101
A61F002/01 |
Claims
1-57. (canceled)
58. A dual guide wire system, comprising: a first guide wire having
a proximal end and a distal end; and a second guide wire having a
proximal end and a distal end, the second guide wire being coupled
to the first guide wire and projecting distally from a distal-end
region of the first guide wire.
59. The dual guide wire system of claim 58, wherein the second
guide wire is made from a nickel-titanium alloy.
60. The dual guide wire system of claim 58, wherein the second
guide wire is made from a nickel-titanium alloy.
61. The dual guide wire system of claim 58, wherein the second
guide wire is made from a nickel-titanium alloy.
62. A dual guide wire system, comprising: a first guide wire made
from a hollow tubular member having a lumen throughout its length
and an aperture within a wall of the tubular member positioned
within the distal-end region; and a second guide wire having a
proximal end and a distal end, the second guide wire being slidable
within the lumen of the first guide wire, the distal end of the
second guide wire extending through the aperture in the first guide
wire.
63. The dual guide wire system of claim 62, wherein the aperture in
the first guide wire is a slot.
64. The dual guide wire system of claim 62, wherein the aperture in
the first guide wire directs the distal end of the second guide
wire in a particular direction relative to the position of the
distal end portion of the first guide wire.
65. The dual guide wire system of claim 62, wherein the second
guide wire is made from a nickel-titanium alloy.
66. The dual guide wire system of claim 62, wherein the first guide
wire includes a structure for holding a filter device.
67. The dual guide wire system of claim 66, wherein the structure
is movable between a collapsed position and an expanded
position.
68. The dual guide wire system of claim 62, wherein the distal
portion of the second guide wire is biased to move away from the
first guide wire.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to filtering devices
used when an interventional procedure is being performed in a
stenosed or occluded region of a biological vessel to capture
embolic material that may be created and released into the vessel
during the procedure. The present invention is more particularly
directed to an embolic filtering device for use in a bifurcated
vessel, such as, for example, a renal artery or carotid artery.
[0002] Numerous procedures have been developed for treating
occluded blood vessels to allow blood to flow without obstruction.
Such procedures usually involve the percutaneous introduction of an
interventional device into the lumen of the artery, usually by a
catheter. One widely known and medically accepted procedure is
balloon angioplasty in which an inflatable balloon is introduced
within the stenosed region of the blood vessel to dilate the
occluded vessel. The balloon dilatation catheter is initially
inserted into the patient's arterial system and is advanced and
manipulated into the area of stenosis in the artery. The balloon is
inflated to compress the plaque and press the vessel wall radially
outward to increase the diameter of the blood vessel, resulting in
increased blood flow. The balloon is then deflated to a small
profile so that the dilatation catheter can be withdrawn from the
patient's vasculature and the blood flow resumed through the
dilated artery. As should be appreciated by those skilled in the
art, while the above-described procedure is typical, it is not the
only method used in angioplasty.
[0003] Another procedure is laser angioplasty which utilizes a
laser to ablate the stenosis by super heating and vaporizing the
deposited plaque. Atherectomy is yet another method of treating a
stenosed biological vessel in which cutting blades are rotated to
shave the deposited plaque from the arterial wall. A vacuum
catheter during this procedure.
[0004] In the procedures of the kind referenced above, abrupt
reclosure may occur or restenosis of the artery may develop over
time, which may require another angioplasty procedure, a surgical
bypass operation, or some other method of repairing or
strengthening the area. To reduce the likelihood of the occurrence
of abrupt reclosure and to strengthen the area, a physician can
implant an intravascular prosthesis for maintaining vascular
patency, commonly known as a stent, inside the artery across the
lesion. The stent can be crimped tightly onto the balloon portion
of the catheter and transported in its delivery diameter through
the patient's vasculature. At the deployment site, the stent is
expanded to a larger diameter, often by inflating the balloon
portion of the catheter.
[0005] The above non-surgical interventional procedures, when
successful, avoid the necessity of major surgical operations.
However, there is one common problem which can become associated
with all of these non-surgical procedures, namely, the potential
release of embolic debris into the bloodstream that can occlude
distal vasculature and cause significant health problems to the
patient. For example, during deployment of a stent, it is possible
that the metal struts of the stent can cut into the stenosis and
shear off pieces of plaque that can travel downstream and lodge
somewhere in the patient's vascular system. Pieces of plaque
material are sometimes generated during a balloon angioplasty
procedure and become released into the bloodstream. Additionally,
while complete vaporization of plaque is the intended goal during
laser angioplasty, sometimes particles are not fully vaporized and
enter the bloodstream. Likewise, not all of the emboli created
during an atherectomy procedure may be drawn into the vacuum
catheter and, as a result, enter the bloodstream as well.
[0006] When any of the above-described procedures are performed in
the carotid arteries, the release of emboli into the circulatory
system can be extremely dangerous and sometimes fatal to the
patient. Debris carried by the bloodstream to distal vessels of the
brain can cause cerebral vessels to occlude, resulting in a stroke,
and in some cases, death. Therefore, although cerebral percutaneous
transluminal angioplasty has been performed in the past, the number
of procedures performed has been somewhat limited due to the
justifiable fear of an embolic stroke occurring should embolic
debris enter the bloodstream and block vital downstream blood
passages.
[0007] Medical devices have been developed to attempt to deal with
the problem created when debris or fragments enter the circulatory
system following vessel treatment utilizing any one of the
above-identified procedures. One approach which has been attempted
is the cutting of any debris into minute sizes which pose little
chance of becoming occluded in major vessels within the patient's
vasculature. However, it is often difficult to control the size of
the fragments which are formed, and the potential risk of vessel
occlusion still exists, making such a procedure in the carotid
arteries a high-risk proposition.
[0008] Other techniques include the use of catheters with a vacuum
source which provides temporary suction to remove embolic debris
from the bloodstream. However, as mentioned above, there can be
complications associated with such systems if the vacuum catheter
does not remove all of the embolic material from the bloodstream.
Also, a powerful suction could cause trauma to the patient's
vasculature.
[0009] Another technique which has had some success utilizes a
filter or trap downstream from the treatment site to capture
embolic debris before it reaches the smaller blood vessels
downstream. The placement of a filter in the patient's vasculature
during treatment of the vascular lesion can reduce the presence of
the embolic debris in the bloodstream. Such embolic filters are
usually delivered in a collapsed position through the patient's
vasculature and then expanded to trap the embolic debris. Some of
these embolic filters are self expanding and utilize a restraining
sheath which maintains the expandable filter in a collapsed
position until it is ready to be expanded within the patient's
vasculature. The physician can causing the filter to expand at the
desired location. Once the procedure is completed, the filter can
be collapsed, and the filter, with the trapped embolic debris, can
then be removed from the vessel. While a filter can be effective in
capturing embolic material, the filter still needs to be collapsed
and removed from the vessel. During this step, there is a
possibility that trapped embolic debris can backflow through the
inlet opening of the filter and enter the bloodstream as the
filtering system is being collapsed and removed from the patient.
Therefore, it is important that any captured embolic debris remain
trapped within this filter so that particles are not released back
into the biological vessel.
[0010] Some prior art expandable filters are attached to the distal
end of a guide wire or guide wire-like member which allows the
filtering device to be steered in the patient's vasculature as the
guide wire is positioned by the physician. Once the guide wire is
in proper position in the vasculature, the embolic filter can be
deployed to capture embolic debris. The guide wire can then be used
by the physician to deliver interventional devices, such as a
balloon angioplasty dilatation catheter or a stent delivery
catheter, to perform the interventional procedure in the area of
treatment. After the procedure is completed, a recovery sheath can
be delivered over the guide wire using over-the-wire techniques to
collapse the expanded filter for removal from the patient's
vasculature.
[0011] When the treatment area is positioned proximate and upstream
to a vessel bifurcation, it is sometimes necessary to place a
single embolic filter in each of the branches of the bifurcated
vessel. Utilizing a separate filter for each branch of the artery,
however, can require the use of a larger delivery catheter and may
occupy more space within the treatment site. As the filter for each
branch of the vessel must be delivered and deployed individually,
the use of multiple filters requires additional time to route and
deploy the filters. Also, as the embolic filters are being removed
from the branch vessels, captured embolic particles may be released
from the filters and flow downstream through voids between the
filters and a special interventional device which has a large lumen
in order to cross over both wires.
[0012] What has been needed is an expandable filter assembly for
use in bifurcated vessels which can be deployed within, and
retrieved from, each branch of the vessel simultaneously. An
expandable filter also is needed which reduces the voids
encountered between the individual filters and the vessel wall
during retrieval of individual filters from the branches of a
bifurcated vessel. The present invention satisfies these and other
needs.
SUMMARY OF THE INVENTION
[0013] The present invention provides a bifurcated embolic
protection device which is designed to remove emboli from
bifurcated biological vessels. The present invention includes a
bifurcated embolic filter having legs which may be dispersed into
individual branches of a bifurcated vessel while minimizing voids
between the filter and the bifurcated vessel. In this manner, the
possibility of emboli floating downstream through either of the
branch vessels is minimized.
[0014] In one aspect of the present invention, an embolic filtering
device for use in a bifurcated biological vessel includes a
delivery device having a first guide wire for directing the embolic
filtering device to a first branch of the bifurcated vessel. The
first guide wire has a proximal end and a distal end. The delivery
device also has a second guide wire for directing the embolic
filtering device to a second branch of the bifurcated vessel. This
second guide wire also has a proximal end and a distal end. The
second guide wire is coupled to the first guide wire and projects
distally from a distal-end region of the first guide wire. The
intersection between the first guide wire and the second guide wire
forms a junction.
[0015] The embolic filtering device includes a filter support
having a first deployment member and a second deployment member. In
one aspect of the present invention, the first deployment member
can be formed an expandable first loop and the second deployment
member formed as an expandable second loop. Each of the first and
second loops includes a first end, a second end and an apex
positioned between the first end and the second end. The first and
second ends of the first and second loops are coupled to the first
guide wire at a position proximate to the junction between the
first guide wire and the second guide wire and proximal to the
junction. Each of the first and second loops includes a preset
deflection proximate the first end and second end of the loop to
permit the loop to diverge from a longitudinal axis of the first
guide wire at the deflection of the loop.
[0016] The embolic filtering device further includes a filter
element having an opening at a proximal end coupled to the filter
support. The filter element includes a first leg which extends
distally toward the distal end of the first guide wire from the
first loop of the filter support. The first leg tapers toward a
distal end of the first leg. The filter element includes a second
leg which extends distally toward the distal end of the second
guide wire from the second loop of the filter support. The second
leg tapers toward a distal end of the second leg. The distal ends
of the first leg and the second leg each include an aperture. The
filter element further includes a crotch at a junction between the
first leg and the second leg. With the filter element coupled to
the filter support, the crotch of the filter element is positioned
distal to the junction between the first guide wire and the second
guide wire. The distal-end region of the first guide wire extends
through the first leg of the filter element and through the
aperture at the distal end of the first leg of the filter element
while the second guide wire extends through the second leg of the
filter element and through the aperture at the distal end of the
second leg of the filter element.
[0017] In a detailed aspect of the invention, the distal end of the
first guide wire and the distal end of the second guide wire each
includes a coil tip. In another detailed aspect, the first guide
wire and the second guide wire form a plane. A center of the first
loop is positioned substantially on the plane between the first
guide wire and the second guide wire on a side opposite from the
second guide wire. A center of the second loop is positioned
substantially on the plane between the first guide wire and the
second guide wire, but on the same side as the second guide wire.
In one particular embodiment of the present invention, the first
loop and the second loop are positioned substantially
longitudinally aligned along the first guide wire, while in another
embodiment the first loop and the second loop are positioned
longitudinally offset along the first guide wire. In a further
aspect, the size of the perimeter of the first loop and the size of
the perimeter of the second loop are nonequal. The opening at the
proximal end of the filter element is coupled to the first loop and
to the second loop. The opening of the filter element is coupled to
a portion of the perimeter of the first loop of the filter support
defined by a first position on the perimeter of the first loop and
a second position on the perimeter of the first loop. Likewise, the
opening of the filter element can be coupled to a portion of the
perimeter of the second loop of the filter support defined by a
first position on the perimeter of the second loop and a second
position on the perimeter of the second loop. The first position on
each of the first and second loops is located between the first end
of the loop and the center of the loop, while the second position
on each of the first and second loops is located between the second
end of the loop and the center of the loop. In another detailed
aspect of the first and second guide wires, the proximal end of the
second guide wire is coupled to the first guide wire within the
distal-end region of the first guide wire. In another detailed
aspect of the first and second guide wires, the first guide wire
further includes a hollow wire having a lumen throughout its length
and an aperture within a wall of the wire positioned within the
distal-end region of the first guide wire. In this aspect, the
second guide wire is slidably coupled to the first guide wire and
contained within the lumen of the first guide wire. The proximal
end of the second guide wire extends beyond the proximal end of the
first guide wire and the distal-end region of the second guide wire
projects from the aperture of the first guide wire. In an
additional detailed aspect of the invention, the length of the
first leg of the filter element and the length of the second leg of
the filtering element are nonequal.
[0018] In another aspect of the invention, an apparatus for
filtering embolic material from a bifurcated biological vessel
includes the embolic filtering device described above and a handle
and a restraining sheath. The handle includes extending and
retracting means. The restraining sheath includes a proximal end, a
distal end and a lumen therebetween. The proximal end of the sheath
is coupled to a distal end of the handle. The delivery device is
contained within the lumen of the sheath and has a clearance fit
with the sheath lumen. The filter support is extendible beyond the
distal end of the sheath and retractable into the sheath by the
means for extending and retracting the delivery device which
correspondingly extends and retracts the filter support within the
sheath. The first loop and the second loop are contracted and
substantially parallel to the first guide wire upon retraction of
the delivery device into the sheath, and the first loop and the
second loop being expanded and project away from the first guide
wire upon extension beyond the distal end of the sheath. The
opening of the filter element is opened and closed when the first
loop and second loop of the filter support are extended from and
retracted into the sheath.
[0019] It is to be understood that the present invention is not
limited by the embodiments described herein. The present invention
can be used in arteries and other biological vessels. Other
features and advantages of the present invention will become more
apparent from the following detailed description of the invention,
when taken in conjunction with the accompanying exemplary
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a perspective view of a particular embodiment of
an apparatus for filtering emboli in a bifurcated biological vessel
embodying features of the present invention.
[0021] FIG. 2 is an elevational view, partially in cross section,
of the apparatus for filtering emboli of FIG. 1 as it is being
delivered to the location of a bifurcated biological vessel
downstream from an area to be treated.
[0022] FIG. 3 is an elevational view, partially in cross section,
similar to that shown in FIG. 2, wherein the embolic filtering
device is deployed within the bifurcated biological vessel.
[0023] FIG. 4 is an elevational view, partially in cross section,
of an alternative embodiment of the guide wires of the embolic
filtering device.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] Turning now to the drawings, in which like reference
numerals represent like or corresponding elements in the drawings,
FIG. 1 illustrates one particular embodiment of an apparatus 20 for
filtering embolic material from a bifurcated vessel incorporating
features of the present invention. The apparatus includes an
embolic filtering device 21 designed to capture embolic debris
which may be created and released into a bifurcated biological
vessel during an interventional procedure. The embolic filtering
device 21 includes an expandable bifurcated filter assembly 22
having a self-expanding filter support 24 and a bifurcated filter
element 26 attached thereto. In this particular embodiment, the
expandable filter assembly 22 is mounted onto the distal portion of
a bifurcated delivery device 27 including a first elongated (solid
or hollow) cylindrical shaft, such as a first guide wire 28, and a
second elongated (solid or hollow) cylindrical shaft, such as a
second guide wire 29. The first guide wire has a proximal end which
extends outside the patient and is manipulated by the physician to
deliver the filter assembly into the target area in the patient's
vasculature. A restraining or delivery sheath 30 extends coaxially
along the delivery device 27 in order to maintain the expandable
filter assembly 22 in its collapsed position until it is ready to
be deployed within the patient's vasculature. The expandable filter
assembly may be deployed by the physician by simply extending the
filter assembly 22 beyond the distal end of the restraining sheath
30. Alternatively, the expandable filter assembly is deployed by
retracting the sheath proximally to expose the expandable filter
assembly. Once the filter assembly is extended, the self-expanding
filter support 24 immediately begins to expand within the
biological vessel (see FIG. 3), causing the filter element 26 to
expand as well.
[0025] The delivery device 27 extends through the filter support 24
and to the coil tips 32, 34 of the first 28 and second 29 guide
wires. The full-length delivery device allows the physician to
control the proximal end 35 of the first guide wire in order to
steer the distal coil tips 32, 34 into the desired branches of the
bifurcated vessel when delivering the embolic filtering device 21
through the patient's vasculature.
[0026] In FIGS. 2 and 3, the embolic filtering device 21 is shown
as it is being delivered within an artery 36 or other biological
vessel of the patient. More particularly, FIG. 3 shows the embolic
filtering device 21 in its expanded position within the patient's
artery 36. This portion of the artery 36 has a treatment site 38 in
which atherosclerotic plaque 40 has built up against the inside
wall 42 of an artery 36 of the patient. The filter assembly 22 is
to be placed at the bifurcation 37 of the vessel which is distal
to, and downstream from, the treatment site 38. For example, the
therapeutic interventional procedure may include the implantation
of a stent (not shown) to increase the diameter of an occluded
artery and increase the flow of blood therethrough. It should be
appreciated that the embodiments of the apparatus 20 described
herein are illustrated and described by way of example only and not
by way of limitation. Also, while the present invention is
described in detail as applied to a bifurcated artery of the
patient, those skilled in the art will appreciate that it can also
be used in other bifurcated biological vessels. Additionally, the
present invention can be utilized when a physician performs any one
of a number of interventional procedures which generally require an
embolic filtering device to capture embolic debris created during
the procedure, such as balloon angioplasty, laser angioplasty or
atherectomy.
[0027] The filter support 24 includes a first deployment member
shown as a first loop 44 and a second deployment member shown as a
second loop 45 which, upon release from the restraining sheath 30,
expand the filter element 26 into its deployed position within the
artery 36 (FIG. 3). While the deployment members are shown as
self-expanding loops of wire in the present embodiment, those
skilled in the art will appreciate that the deployment members can
take on many shapes and sizes. Embolic particles 46 created during
the interventional procedure and released into the bloodstream are
captured within the deployed filter element 26. The filter element
may include perfusion openings 48, or other suitable perfusion
means, for allowing blood flow through the filter element 26. The
filter element will capture embolic particles which are larger than
the perfusion openings while allowing some blood to perfuse
downstream to vital organs. Although not shown, a balloon
angioplasty catheter can be initially introduced within the
patient's vasculature in a conventional SELDINGER technique through
a guiding catheter (not shown).
[0028] The delivery device 27 is disposed through the area of
treatment and the dilatation catheter can be advanced over the
first guide wire 28 within the artery 36 until the balloon portion
is directly in the area of treatment 38. The balloon of the
dilatation catheter can be expanded, expanding the plaque 40
against the wall position of the plaque. After the dilatation
catheter is removed from the patient's vasculature, a stent (not
shown) could be implanted at the treatment site 38 using
over-the-wire or rapid exchange techniques to help hold and
maintain this portion of the artery 36 and help prevent restenosis
from occurring in the area of treatment. The stent could be
delivered to the treatment site on a stent delivery catheter (not
shown) which is advanced from the proximal end of the first guide
wire to the area of treatment.
[0029] The filtering device 21 is shown mounted to the distal
portion of the delivery device 27 with the proximal portion of the
bifurcated filter element 26 disposed in a branching portion of a
trunk vessel 50 of a bifurcated biological vessel. First 52 and
second 54 legs of the filter element are shown disposed within a
first 56 and second 58 branch, respectively, of the bifurcated
vessel. Any embolic debris 46 created during the interventional
procedure will be released into the bloodstream and should enter
the filter element 26. Once the procedure is completed, the
interventional device may be removed from the patient, along with
the filters. The filter assembly 22 can also be collapsed and
removed from the artery 36, taking with it any embolic debris
trapped within the filter element 26. A recovery sheath (not shown)
can be delivered over the first guide wire 28 to collapse the
filter assembly 22 for removal from the patient's vasculature.
[0030] Referring again to FIG. 1, the apparatus 20 for filtering
embolic material from a bifurcated biological vessel may include a
handle 60 which functions to manipulate the embolic filtering
device 21. The handle may be of any type known in the art, such as
pistol-like grip or syringe-type handles. FIG. 1 shows a
syringe-type handle which includes a plunger 62 and a cylinder 64.
The handle may include means for extending and retracting the
delivery device 27 which is coupled to the handle. For instance, in
the embodiment shown the delivery device may be extended and
retracted by respectively pushing and drawing the plunger.
[0031] The elongate sheath 30 includes a first end 66 (proximal
end), a second end 68 (distal end) and a lumen 70 therebetween. The
proximal end 66 of the sheath may be coupled to a distal end 72 of
the handle 60, such as at the cylinder 64, via means which are well
known in the art, such as with an adhesive or by mechanical means.
The lumen of the sheath is sized to contain the delivery device 27
and the filter assembly 22 with a clearance fit such that the
delivery device and the filter assembly can be translated through
the lumen by the extending and retracting means of the handle.
[0032] The materials which can be utilized for the restraining
sheath 30 can be made from polymeric material such as cross-linked
HDPE. The sheath can alternatively be made from a material such as
polyolefin which has sufficient strength to hold the compressed
filter support and has relatively low frictional characteristics to
minimize any friction between the filtering assembly and the
sheath. Friction can be further reduced by applying a coat of
silicone lubricant, such as Microglide.RTM., to the inside surface
of the restraining sheath before the sheath is placed over the
filtering assembly.
[0033] With further reference to FIGS. 2 and 3, the delivery device
27 is contained within the lumen 70 of the sheath 30. The delivery
device includes the first guide wire 28 and the second guide wire
29. The first guide wire 28 may be used to direct the embolic
filtering device 21 to the first branch 56 of the bifurcated vessel
36. As is specifically shown in FIG. 1, the first guide wire 28
includes a first end 35 (proximal end) and a second end 74 (distal
end). The distal end of the first guide wire may include a coil
shape 32 (coil tip) which facilitates in guiding the first guide
wire through the vasculature and preventing injury to the
vasculature. The proximal end 35 (FIG. 1) of the first guide wire
may be coupled to the extending means of the handle 60, such as a
distal end of the plunger 62 portion of the handle. A distal-end
region 76 of the first guide wire may be extendible beyond the
distal end 68 of the sheath 30 and retractable into the sheath by
the means for extending and retracting the delivery device.
[0034] The second guide wire 29 may be used to direct the embolic
filtering device 21 to the second branch 58 of the bifurcated
vessel 36. The second guide wire 29 includes a first end 78
(proximal end) and a second end 80 (distal end). The distal end 80
of the second guide wire may include a coil shape 34 (coil tip)
which facilitates in guiding the second guide wire through the
vasculature and preventing injury to the vasculature. The second
guide wire is coupled to the first guide wire 28 and projects
distally from the distal-end region 76 of the first guide wire with
the intersection between the first guide wire and the second guide
wire forming a junction 82. A plane is also formed between the
first guide wire and the second guide wire. Being coupled to the
first guide wire, the second guide wire may be extendible beyond
the distal end 68 of the sheath 30 and retractable into the sheath
by the means for extending and retracting the delivery device 27.
Upon retraction of the delivery device into the sheath, the second
guide wire is forced to be substantially parallel to the first
guide wire. The second guide wire projects away from the distal-end
region of the first guide wire upon extension of the distal-end
region of the first guide wire beyond the distal end 68 of the
sheath.
[0035] With continued reference to FIGS. 2 and 3, the delivery
device 27 may also include a filter support 24 having an expandable
first loop 44 and an expandable second loop 45. The first 44 and
second 45 loops may each be formed from a wire having a first end
84, 86 and a second end 88, 90. The dimensions of the first 44 and
second 45 loops are determined in most cases by the size of the
lumen of the vessel 36 in which embolic material 46 is sought to be
filtered. The first and second ends of the first and second loops
may be coupled to the first guide wire 28 through methods which are
well known in the art, such as soldering or sandwiching the ends of
the loops between the first guide wire and an annular sleeve (not
shown). The first and second loops may be coupled to the first
guide wire at a position proximate, or alternatively, distal to the
junction 82 between the first guide wire and the second guide wire
29, proximal to the junction and proximate each other. The first
and second loops each diverge from a longitudinal axis of the first
guide wire. The first and second loops may each include a preset
deflection proximate the first and second ends to facilitate the
divergence of the first and second loops from the first guide wire.
The first loop may be positioned such that a center of the first
loop is located substantially on the plane between the first guide
wire and the second guide wire on a side opposite the second guide
wire. Similarly, the second loop may be positioned such that a
center of the second loop is located substantially on the plane
between the first guide wire and the second guide wire on the same
side as the second guide wire.
[0036] The first 44 and second 45 loops may be extendible beyond
the distal end 68 of the sheath 30 and retractable into the sheath
by the means for extending and retracting the delivery device 27
which correspondingly extends and retracts the first and second
loops. When the delivery device 27 is retracted within the sheath
30 (FIG. 2), the first loop 44 and the second loop 45 are
mechanically stressed within their elastic limits to each form a
long narrow loop, with the axis of each loop being substantially
parallel to the longitudinal axis of the first guide wire 28 as
shown in FIG. 2. While in this state, an apex 92 of the first loop
44 and an apex 94 of the second loop 45 each include a tight bend
and consume large areas of a cross-section of the lumen 70 of the
sheath.
[0037] If the apices 92, 94 of the first 44 and second 45 loops are
positioned substantially longitudinally aligned with each other, it
may cause difficulty in retracting the delivery device 27 into the
sheath 30. To facilitate retraction of the delivery device 27 into
the sheath, the first loop and the second loop may be positioned
longitudinally offset along the first guide wire 28. For example,
the second loop may be positioned either proximal or distal to the
first loop along the first guide wire. By having the first and
second loops positioned offset longitudinally, the apices of the
first and second loops enter the sheath at different times and are
longitudinally offset from each other when the first and second
loops are contracted within the lumen of the sheath. Another means
to longitudinally offset the apices of the first and second loops
when the loops are contracted within example, the second loop may
have either a larger or a smaller periphery than the first
loop.
[0038] A suitable composition of nickel-titanium which can be used
to manufacture the first loop 44 and the second loop 45 of the
filter support 24 of the present invention is approximately 55%
nickel and 45% titanium (by weight) with trace amounts of other
elements making up about 0.5% of the composition. The austenite
transformation temperature is between about 0.degree. C. and
20.degree. C. in order to achieve superelasticity at human body
temperature. The austenite temperature is measured by the bend and
free recovery tangent method. The upper plateau strength is about a
minimum of 60,000 psi with an ultimate tensile strength of a
minimum of about 155,000 psi. The permanent set (after applying 8%
strain and unloading), is less than approximately 0.5%. The
breaking elongation is a minimum of 10%. It should be appreciated
that other compositions of nickel-titanium can be utilized, as can
other self-expanding alloys, to obtain the same features of a
self-expanding filter support made in accordance with the present
invention.
[0039] In one example, the first 44 and second 45 loops of the
filter support of the present invention can be fabricated from a
tube or solid wire of nickel-titanium (Nitinol) whose
transformation temperature is below body temperature. After the
loop is formed, the loop is heat treated to be stable at the
desired final shape. The heat treatment also controls the
transformation temperature of the filter support such that it is
super elastic at body temperature. The transformation temperature
is at or below body temperature so that the filter support is
superelastic at body temperature. The filter support is usually
implanted into the target vessel which is smaller than the
perimeter of the filter support in the expanded position so that
the loops of the filter support apply a force to the vessel wall to
maintain the filter support in its expanded position. It should be
appreciated that the filter support can be made from either
superelastic, stress-induced martensite NiTi or shape-memory
NiTi.
[0040] The embolic filtering device 21 may also include a filter
element 26. The filter element may include an opening 96 at a first
end 98 (proximal end) which is coupled to the filter support 24,
such as to the first 44 and second 45 loops. The opening of the
filter element may be coupled to a portion of the perimeter of the
first loop defined by a first position 100 on the perimeter of the
first loop and a second position 102 on the perimeter of the first
loop. The first position on the first loop may be located between
the first end 84 of the first loop and the center of the first
loop. The second position on the first loop may be located between
the second end 88 of the first loop and the center of the first
loop. Likewise, the opening of the filter element may also be
coupled to a portion of the perimeter of the second loop defined by
a first position 104 on the perimeter of the second loop and a
second position 106 on the perimeter of the second loop. The first
position on the second loop may be located between the first end 86
of the second loop and the center of the second loop. The second
position on the second loop may be located between the second end
90 of the second loop and the center of the second loop. As
discussed earlier, the opening of the filter element may be opened
and closed when the first loop and second loop of the filter
support are extended from and retracted into the sheath 30.
[0041] The filter element 26 also includes at least a first leg 52
and a second leg 54 which extend distally from the opening 96 of
the filter element. With the filter element coupled to the filter
support 24, the first leg extends distally from the first loop 44
of the filter support and tapers toward a distal end 108 of the
first leg. The second leg extends distally from the second loop 45
of the filter support and tapers toward a distal end 110 of the
second leg. The distal ends 108, 110 of the first and second legs
may each include an aperture 112, 114. The filter element further
includes a crotch 116 positioned between the first leg and the
second leg. With the filter element coupled to the filter support,
the crotch is positioned distal to the junction 82 between the
first guide wire 28 and the second guide wire 29. The distal-end
region 76 of the first guide wire extends through the first leg 52
of the filter element and projects through the aperture 112 at the
distal end of the first leg. The second guide wire 29 extends
through the second leg 54 of the filter element and projects
through the aperture 114 at the distal end of the second leg. To
facilitate wear resistance between the filter element and the first
and second guide wires, the apertures 112, 114 at the distal ends
of the first and second legs of the filter element may each be
lined with a sleeve 118 and the first and second guide wires may
each extend through the respective sleeve. The ends of the sleeves
can be made from a radiopaque material, such as gold or platinum,
to increase visualization under fluoroscopy. The distal ends of the
first and second legs of the filter element may be positioned
longitudinally offset from each other to reduce the cross profile
of the filter having captured embolic material therein to
facilitate retraction of the embolic filter into the sheath.
[0042] In one embodiment of the present invention, the perimeter of
the opening 96 of the filter element 26 is bonded to the first 44
and second 45 loops to secure the filter element to the filter
support 24 through methods which are well known in the art, such as
with adhesives, heat based bonding, or both. In an alternative
embodiment (not shown), the filter element may be formed with a
series of tab-like projections about the opening. The tab-like
projections may be wrapped around the first and second loops of the
filter support and bonded thereto through the methods
described.
[0043] Polymeric materials which can be utilized to create the
filtering element include, but are not limited to, polyurethane and
Gortex, a commercially available material. Other possible suitable
materials include ePTFE. The material can be elastic or
non-elastic. The wall thickness of the filtering element can be
about 0.00050-0.0050 inches. The wall thickness may vary depending
on the particular material selected. The material can be made into
a pair of legs or similarly sized shapes utilizing blow-mold
technology or dip technology. The other process can be utilized to
create the perfusion openings in the filter material. The perfusion
openings would, of course, be properly sized to catch the
particular size of embolic debris of interest. Holes can be lazed
in a spinal pattern or some similar pattern which will aid in the
re-wrapping of the media during closure of the device.
Additionally, the filter material can have a "set" put in it much
like the "set" used in dilatation balloons to make the filter
element re-wrap more easily when placed in the collapsed
position.
[0044] Referring again to the delivery device 27, FIG. 1 depicts
the first guide wire 28 as a solid wire. The second guide wire 29
is also depicted as a solid wire which is coupled to the distal-end
region 76 of the first guide wire, such as by soldering. In this
embodiment, the first and second guide wires are delivered to the
first 56 and second 58 branches, respectively, of the bifurcated
vessel 36 by advancing the distal end 68 of the sheath 30 to a
position distal to the treatment site 38 and proximal to the vessel
bifurcation 37. The delivery device may be partially extended,
thereby partially extending the filter device 21, and rotated from
the proximal end until the first and second guide wires are aligned
with the first and second branches of the bifurcated vessel. The
delivery device and first and second guide wires can then be
further extended beyond the distal end of the sheath with the
distal-end region 76 (FIG. 4) of the first guide wire 28 entering
the first vessel branch and the distal-end region 120 of the second
guide wire entering the second vessel branch. The first 52 and
second 54 legs of the filter element 26 also enter the first and
second vessel branches with the first and second guide wires,
respectively. Further extension of the delivery device causes
expansion of the filter support 24 within the trunk portion 50 of
the vessel, thereby causing opening of the proximal end 98 of the
filter element and completing deployment of the filter element.
[0045] In an alternative embodiment, FIG. 4 depicts the first guide
wire 28 as a hollow tubular member which acts as a guide wire, such
as a hypotube or polymeric tubing, having a lumen 121 throughout
its length. The second guide wire 29 may include a solid or hollow
wire which is slidably coupled to the first guide wire and
contained within the lumen of the first guide wire. The proximal
end 78 of the second guide wire 29 extends beyond the proximal end
35 of the first guide wire and the distal-end region 120 of the
second guide wire projects from an aperture 122 within the wall of
the distal-end region 76 of the first guide wire. Delivery of the
first and second guide wires of this embodiment is similar to the
method described above. However, the second guide wire may be
translated proximally or distally from the proximal end to
facilitate insertion of the distal-end region of the second guide
wire and the second leg 54 of the filter element 26 into the second
vessel branch 58.
[0046] The bifurcated filter of the present invention permits
filtering of each of the branches of the bifurcated vessel and the
branching portion of the trunk vessel with a single filter without
any open voids between the filter and the vessel. As a result, the
possibility of embolic material floating downstream through either
of the branch vessels is minimized.
[0047] Further modifications and improvements may additionally be
made to the device and method disclosed herein without departing
from the scope of the present invention. Accordingly, it is not
intended that the invention be limited, except as by the appended
claims.
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