U.S. patent application number 09/918991 was filed with the patent office on 2003-02-06 for expandable body cavity liner device.
Invention is credited to Barry, David C., Eder, Joseph C., Porter, Stephen C., Teoh, Clifford, Wallace, Michael P..
Application Number | 20030028209 09/918991 |
Document ID | / |
Family ID | 25441296 |
Filed Date | 2003-02-06 |
United States Patent
Application |
20030028209 |
Kind Code |
A1 |
Teoh, Clifford ; et
al. |
February 6, 2003 |
Expandable body cavity liner device
Abstract
The present invention is an aneurysm treatment device for
treating aneurysms of various shapes and sizes.
Inventors: |
Teoh, Clifford; (Los Altos,
CA) ; Eder, Joseph C.; (Los Altos Hills, CA) ;
Wallace, Michael P.; (Fremont, CA) ; Porter, Stephen
C.; (Fremont, CA) ; Barry, David C.; (Fremont,
CA) |
Correspondence
Address: |
WESTMAN, CHAMPLIN AND KELLY
900 SECOND AVENUE SOUTH
SUITE 1600- INTERNATIONAL CENTRE
MINNEAPOLIS
MN
55402-3319
US
|
Family ID: |
25441296 |
Appl. No.: |
09/918991 |
Filed: |
July 31, 2001 |
Current U.S.
Class: |
606/191 |
Current CPC
Class: |
A61B 17/12172 20130101;
A61B 17/12022 20130101; A61B 17/12113 20130101 |
Class at
Publication: |
606/191 |
International
Class: |
A61M 029/00 |
Claims
What is claimed is:
1. An aneurysm liner for treating an aneurysm in a parent vessel,
the aneurysm liner comprising: a liner sac made of an inelastic
material having a sac and folded or pleated expansion zones, the
sac, under ambient external pressure being expandable to a first
peripheral dimension under influence of a first internal pressure
and the expansion zones being expandable to a second, larger
peripheral dimension, under influence of a second internal pressure
greater than the first internal pressure.
2. The aneurysm liner of claim 1 wherein the one or more folded or
pleated expansion zones are disposed on the liner sac and remain in
an unexpanded configuration at the first internal pressure and
assume an expanded configuration at the second internal
pressure.
3. The aneurysm liner of claim 2 wherein the one or more expansion
zones each comprise a pleated portion of the inelastic material
folded upon itself in an accordion-like configuration and remaining
folded under the first internal pressure.
4. The aneurysm liner of claim 3 wherein the folded portion unfolds
when subjected to the second internal pressure.
5. The aneurysm liner of claim 4 wherein the liner sac is
perforated to permeate blood from the aneurysm to the parent
vessel.
6. An aneurysm liner, comprising: a structure having a proximal
portion and a distal portion, the proximal portion and distal
portion being configured to preferentially permeate embolics
introduced therein through the distal portion.
7. The aneurysm liner of claim 6 wherein the distal portion has
perforations sized to permeate embolics.
8. The aneurysm liner of claim 7 wherein the proximal portion has
perforations sized to permeate blood but to inhibit permeation of
embolics.
9. The aneurysm liner of claim 8 wherein the proximal portion
comprises a liner portion supported by expandable struts.
10. The aneurysm liner of claim 9 wherein the distal portion is
formed of the struts, free of any covering.
11. The aneurysm liner of claim 10 wherein the distal portion is
comprised of a liner portion supported by the struts.
12. The aneurysm liner of claim 9 wherein the liner portion
comprises a shape memory polymer material.
13. The aneurysm liner of claim 12 wherein the shape memory polymer
is actuable between a first low profile delivery configuration in
which it confines the struts to a low profile configuration and a
relaxed, expanded configuration.
14. An aneurysm treatment device, comprising: an expandable liner
sac; and a retaining member within the liner sac, the retaining
member releasably retaining therein a retained portion of the liner
sac under a first internal pressure within the liner sac and
releasing at least part of the retained portion under a second
internal pressure, higher than the first pressure.
15. The aneurysm treatment device of claim 14 wherein the retaining
member is oriented in the liner sac such that when the retained
portion is released, it increases a deployed axial length of the
liner sac.
16. The aneurysm treatment device of claim 14 wherein the retaining
member comprises: a coil disposed within the liner sac and having
the retained portion of the liner sac tucked within an interior of
the coil.
17. The aneurysm treatment device of claim 15 wherein the coil is
configured such that when it releases the retained portion, the
coil floats within the liner sac.
18. The aneurysm treatment device of claim 15 wherein the coil
remains connected to the liner sac after it has released the
retained portion of the liner sac.
19. An aneurysm treatment device, comprising: a sac configured to
receive internal pressure therein and to increase a radial
dimension thereof and decrease an axial dimension thereof with
increases in the internal pressure.
20. The aneurysm treatment device of claim 19 wherein the sac is
formed of an axially oriented polymer material.
21. The aneurysm treatment device of claim 20 wherein the sac is
releasably connected to an elongate delivery member.
22. The aneurysm treatment device of claim 19 wherein the sac is
perforated.
23. The aneurysm treatment device of claim 19 wherein the sac has
an expanded radial dimension sufficient to bridge a neck of an
aneurysm.
24. An aneurysm treatment device, comprising: an elongate delivery
member; and a liner formed of shape memory polymer material.
25. The aneurysm treatment device of claim 24 wherein the liner has
a compressed, low profile configuration and a relaxed expanded
configuration.
26. The aneurysm treatment device of claim 25 wherein the liner is
configured to maintain its compressed configuration during delivery
to a treatment site and to assume the relaxed configuration upon
being subjected to an elevated temperature above that during
delivery.
27. The aneurysm treatment device of claim 24 wherein the liner
comprises a mesh.
28. The aneurysm treatment device of claim 24 wherein the liner
comprises a weave.
29. An aneurysm treatment device, comprising: an expandable liner
having a medial portion formed of a fabric material and proximal
and distal portions formed of a thin material relative to the
fabric material in the medial portion.
30. The aneurysm treatment device of claim 29 wherein the proximal
and distal portions comprise a flowable material, flowed around
proximal and distal ends of the medial portion, respectively.
31. The aneurysm treatment device of claim 30 wherein the flowable
material comprises urethane.
32. The aneurysm treatment device of claim 29 wherein the fabric
material forms an expandable braid.
33. The aneurysm treatment device of claim 29 wherein the fabric
material forms an expandable mesh.
34. The aneurysm treatment device of claim 29 wherein the medial
portion terminates in substantially constant diameter, unfolded,
proximal and distal ends.
35. The aneurysm treatment device of claim 34 wherein the proximal
and distal ends are covered by the thin material.
36. The aneurysm treatment device of claim 35 wherein the thin
material forming the proximal portion has an outer diameter that
tapers proximally.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention deals with a system for treating a
vascular cavity. More specifically, the present invention is
directed to vascular cavity liners and vascular cavity neck
bridges.
[0002] While the present discussion proceeds with respect to
aneurysms, it will be appreciated that it can be applied to other
vascular cavities (such as vessels, lumens, etc.) as well. An
aneurysm is a localized stretching or distension of an artery due
to a weakening of the vessel wall. For example, "berry"aneurysms,
i.e., small spherical distensions, occur in the vessels of the
brain. The distension--often referred to as the aneurysm sac--is
related to defects in the muscular coating of the artery and is
probably degenerative in origin. Rupture of aneurysms account for
the majority of spontaneous hemorrhages. Approximately 25,000
intracranial aneurysms rupture every year in North America.
[0003] Several methods of treating aneurysms have been attempted,
with varying degrees of success. At present, the treatment of
aneurysms with drugs is substantially ineffective. Also,
extra-vascular surgery, referred to as open craniotomy, for the
purpose of preserving the parent artery is replete with
disadvantages. A patient subject to open craniotomy for
intercranial aneurysms typically must undergo general anesthesia,
surgical removal of part of the skull, brain retraction, dissection
around the neck of the sac, and placement of a clip on the parent
artery to prevent bleeding or rebleeding.
[0004] Alternative treatments include endovascular occlusion where
the interior of the aneurysm is entered with a guidewire or a
microcatheter. An occlusion is formed within the sac with an
intention to preserve the parent artery. One means for forming a
mass is through the introduction of an embolic agent within the
sac. Examples of embolic agents include a detachable coil, which is
detached from the end of a guidewire, a liquid polymer which
polymerizes rapidly on contact with blood to form a firm mass, and
embolic particles.
[0005] Endovascular occlusion is not without drawbacks. For
example, there is a risk of overfilling the sac and consequent
embolic agent migration into the parent vessel. Overfilling of the
sac also generates additional pressure in the aneurysm.
[0006] Another means for forming a mass in the aneurysm sac
involves the placement of an expandable balloon or liner in the
aneurysm. Detachable occlusion balloons have been used for a number
of medical procedures. These balloons are carried at the end of a
catheter and, once inflated can be detached from the catheter. Such
a balloon may be positioned within an aneurysm, filled and then
detached from the catheter. Deploying the balloon within the
aneurysm can be rather difficult due to the high rates of blood
flow through the aneurysm. Elastic balloons have exhibited problems
with respect to performance and have not been used endovascularly
in some time.
[0007] This aneurysm filling technique also has its problems. As
the balloon is filled, the operator must be very careful not to
overfill the balloon due to possible risk of rupturing the
aneurysm. Accordingly, the balloon may be too small, potentially
resulting in the release of the balloon from the aneurysm into the
blood stream. Furthermore, the balloon often does not mold or shape
to the odd-shaped contours of the aneurysm leaving room for blood
to continue flowing through the aneurysm, or generating undesired
pressure on the aneurysm wall.
[0008] Aneurysm liners are composed of a permeable liner sac which
is placed in the aneurysm and filled to occlude the aneurysm. A
guidewire is inserted in the liner. The guidewire carries the liner
through the vasculature to deploy the liner in the aneurysm.
[0009] All of the present systems for treating aneurysms have
disadvantages as well. For example, while the aneurysm liner
concept is intuitively attractive, it has posed a number of
technical challenges. One primary challenge involves the difficulty
in producing a material that is robust enough to contain embolic
material without inhibiting the ability of the embolics to conform
to the aneurysm geometry itself, rather than the geometry of the
liner. For example, the elastic materials discussed above generally
require to much force to deform, and inelastic materials that
deform readily do not have adequate memory to conform to the
aneurysmal wall.
[0010] Different types of aneurysms also present different
challenges. For example, aneurysms which have a particularly wide
opening between the aneurysm sac and the parent vessel ("wide neck
aneurysms") present difficulties concerning the retention of
embolic materials. Specifically, wide neck aneurysms make it very
difficult to maintain the embolics, or occlusive materials, within
the aneurysmal sac. This is especially true of liquid embolic
materials. Of course, should the embolic material enter the parent
vessel, it poses an undesirable risk of occlusion in the parent
vessel.
[0011] Some current aneurysm liner concepts are inadequate in
treating larger aneurysms. For example, some liner concepts involve
forming the aneurysm liner of a woven or braided polymeric material
such as polypropylene, polyester, nylon, urethane, teflon, etc.
However, these mesh materials are difficult to use in treating
aneurysms larger than, for example, twelve millimeters in diameter.
Such mesh materials result in an assembly which is too bulky when
collapsed down onto the catheter for delivery. In other words, the
amount of materials required to fill a relatively large aneurysm is
very difficult to collapse down into a constrained, low profile,
delivery configuration small enough to be delivered and deployed
without excess friction on the walls of the delivery catheter or
other delivery lumen.
SUMMARY OF THE INVENTION
[0012] The present invention is a vascular cavity treatment device
for treating vascular cavities of various shapes and sizes and will
be discussed by way of example as an aneurysm treatment device.
[0013] In one embodiment, the aneurysm treatment device is formed
as an aneurysm liner having portions folded over on itself when
deployed at ambient internal pressure. However, when the pressure
increases, the folded over portions unfold to increase the size of
the aneurysm liner in the direction of unfilled portions of the
aneurysmal sac.
[0014] The liner can be deployed using other means such as struts
or shape memory polymer as well. The device itself can also be
formed of shape memory polymer material.
[0015] In another embodiment, the aneurysm treatment device is
formed to allow embolic material to preferentially exit the distal
end of the aneurysm treatment device. This allows the embolic
material to fill irregularly shaped portions of the aneurysm sac,
without escaping though the neck of the aneurysmal sac.
[0016] In yet another embodiment, the present invention includes a
shape memory polymer woven or braided with a density sufficient to
inhibit movement of embolic material, once introduced into the
liner, through the neck portion of the liner. Similarly, the shape
memory polymer can be disposed on an aneurysm neck bridge.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIGS. 1A-1C illustrate the deployment of an aneurysm liner
in an aneurysm.
[0018] FIGS. 2A-2D illustrate deployment of an aneurysm liner
having folded or pleated portions that unfold into irregularly
shaped areas of the aneurysm sac.
[0019] FIG. 2E shows the embodiment of an aneurysm liner
illustrated in FIGS. 2A-2D with perforations therein.
[0020] FIGS. 3A and 3B illustrate an aneurysm treatment device
which allows embolic material to preferentially exit the distal end
thereof, wherein FIG. 3A shows the treatment device in a collapsed
position and FIG. 3B shows the device in a deployed position.
[0021] FIGS. 4 and 5 illustrate two different embodiments of an
aneurysm treatment device that allows embolic material to
preferentially exit the distal end thereof.
[0022] FIGS. 6A-6D illustrate a shape memory polymer mesh aneurysm
liner connected to a catheter (FIGS. 6A and 6B) and connected to a
delivery wire (FIGS. 6C and 6D).
[0023] FIGS. 7A-7C illustrate an aneurysm treatment device that
includes a shape memory polymer connected to a neck bridge
device.
[0024] FIGS. 8A and 8B show an aneurysm treatment device made of a
plurality of different materials.
[0025] FIGS. 9A-9C show another embodiment of the present
invention.
[0026] FIGS. 10A-10D show still another embodiment of the present
invention.
[0027] FIG. 10E shows the device of FIGS. 10A-10D in a small, or
narrow, neck aneurysm.
DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS
[0028] FIGS. 1A-1C illustrate a portion of an aneurysm treatment
device 10 in a vessel 12 which has an aneurysm 14 therein, and thus
illustrate the general context of the present invention. Though the
embodiments discussed herein are discussed in conjunction with an
aneurysm, it will be appreciated that they can be used in
substantially any vascular cavity. Aneurysm 14 is defined by
aneurysmal sac 16 and neck 18. Device 10 includes, in the
embodiment illustrated, delivery catheter 20, a pair of extender
coils 21 and 22 and an expandable liner 24. Delivery catheter 20
has a proximal end that extends proximally to a position where it
is manipulable by an operator. The distal end of catheter 20 is
releaseably connected to the liner 24 and coil 21. Coils 21 and 22
can either be attached to the liner or catheter, or unattached.
[0029] When in the insertion position shown in FIG. 1A, coils 21
and 22 are axially aligned with one another, their length is
sufficient to substantially hold liner 24 in a low profile position
for insertion and manipulation within the vasculature. In one
embodiment, coils 21 and 22 are axially aligned with one another
and with catheter 20 through the use of a guidewire 26 which is
disposed within the lumen of catheter 20, through coils 21 and 22
and liner 24, and out the distal end of coil 22 and liner 24. Coils
21 and 22 are held in an axially aligned conformation by guidewire
26 such that coils 21 and 22 substantially conform to the curvature
of guidewire 26. Coils 21 and 22, rather than guidewire 26, can act
to extend and even tension liner 24.
[0030] FIG. 1B shows that treatment device 10 has been positioned
through vessel 12 and neck 18 into the sac 16 of aneurysm 14.
Similar items are similarly numbered to those shown in FIG. 1A. In
use, aneurysm treatment device 10 can be preloaded or back loaded
onto guidewire 26. Guidewire 26 is manipulated through the
vasculature from the entry site (such as the femoral artery) to the
region of vessel 12 containing the aneurysm. The distal tip of
guidewire 26 is advanced across the neck 18 of aneurysm 14 and into
the aneurysm sac 16. This can be done using any desirable
visualization technique. In one embodiment, catheter 20 is placed
over guidewire 26 prior to positioning guidewire 26 in the
vasculature, with several centimeters of guidewire 26 extending
distal of the distal tip of catheter 20. Therefore, when the distal
end of guidewire 26 has passed the aneurysm neck 18, catheter 20 is
positioned just proximal of neck 18. Treatment device 10 is then
advanced into the aneurysm sac 16.
[0031] In another embodiment, guidewire 26 is placed in the
vasculature first. Once the distal end of guidewire 26 is moved
past the aneurysm neck 18, into the aneurysm sac 16, catheter 20 is
advanced over guidewire 26 such that the extender coils 21 and 22
are pushed distally along the guidewire by the catheter 20 until
the aneurysm treatment device 10 is in place in the aneurysm sac
16.
[0032] FIG. 1C illustrates treatment device 10 deployed in aneurysm
sac 16 in accordance with one embodiment. Similar items are
similarly numbered to those shown in FIGS. 1A and 1B. Once device
10 is substantially fully within aneurysm sac 16, guidewire 26 is
retracted proximally, but liner 24 remains connected to delivery
catheter 20. The distal end of delivery catheter 20 holds
expandable liner 24 in position within the aneurysm sac 16 while
expandable liner 24 is filled with embolics. Expansion of liner 24
occurs after the distal end of guidewire 26 is retracted from the
coils 21 and 22.
[0033] As shown in FIG. 1C, once guidewire 26 has been retracted,
coils 21 and 22 recoil away from axial alignment with one another
toward the periphery of liner 24. In one illustrative embodiment,
coils 21 and 22 are biased to extend in opposite directions to
enhance deployment of, and expansion of, liner 24 within aneurysm
sac 16. In another embodiment, one or more intermediate coils are
aligned over guidewire 26, and, as guidewire 26 is retracted, the
intermediate coil(s) fall away and float freely within the
liner.
[0034] Embolic material can now be introduced into liner 24 through
catheter 20 using substantially any desired method. Such methods
include, for example, advancing coils or particles into liner 24,
pushing the embolic material into catheter 20 with guidewire 26
completely removed, or infusing or injecting embolic material
through catheter 20 into liner 24. Liner 24 is thus filled with a
common embolic agent, such as detachable coils, particles, etc.
[0035] Once liner 24 is filled, it is unable to be removed through
aneurysm neck 18. Therefore, it is released from delivery catheter
20 and delivery catheter 20 is removed from the treatment site.
Detachment of liner 24 from catheter 20 can be accomplished using
any desired method, such as using electrolytic detachment,
traction-based detachment, or other mechanical, electrical,
heat-based, magnetic, chemical or other detachment.
[0036] FIGS. 1A-1C illustrate that device 10 is configured for
convenient treatment of aneurysm 14, and in particular, a generally
symmetrically shaped aneurysm. However, asymmetrically shaped
aneurysm sacs, or those having an otherwise irregular geometrical
shape present other problems. For example, if aneurysm sac 16 had a
cavity extending out one side thereof, it may be difficult for
liner 24 to fill that portion of the aneurysm sac.
[0037] FIGS. 2A-2D illustrate another embodiment of an aneurysm
treatment device 30 in accordance with another embodiment of the
present invention. Device 30 is similar to device 10 in that it is
illustratively connected to a delivery catheter 20 and has coils 21
and 22 disposed within a liner 24, and is configured for
advancement over guidewire 26. However, in the embodiment
illustrated in FIGS. 2A-2D, liner 24 is also provided with a
plurality of expansion zones designated by numerals 32, 34 and 36
in the Figures. Expansion zones 32-36 help to enable liner 24 to
fill asymmetric portions (irregular portions) of an aneurysm sac.
For example, in FIGS. 2A-2D, aneurysm sac 16 has an asymmetric lobe
38. The expansion zones 32, 34 and 36 on aneurysm treatment device
30 enable it to more completely fill the asymmetrically shaped
aneurysm sac 16.
[0038] FIG. 2A shows aneurysm treatment device 30 in vessel 12
located proximal to neck 18 of aneurysm sac 16. FIG. 2B shows
aneurysm treatment device 30 disposed within aneurysm sac 16, still
in its collapsed, insertion position.
[0039] FIG. 2C shows liner 24 expanded somewhat to a first
peripheral dimension, in which none of the expansion zones 32, 34
or 36 have yet been expanded. It can be seen that, in this
conformation, aneurysm liner 24 is illustratively a substantially
symmetrically shaped aneurysm liner under a first internal
pressure, only slightly elevated over ambient pressure. However,
expansion zones 32, 34 and 36 enable liner 24 to expand in an
asymmetrical fashion, when additional internal pressure (e.g., 0-5
atmospheres and illustratively greater than zero atmosphere and
less than two atmosphere or in a range of approximately 1-2
atmospheres) is applied within liner 24.
[0040] In one illustrative embodiment, liner 24 is an inelastic
polymer film (either with or without perforations or openings
therein). Expansion zones 32, 34 and 36 are illustratively formed
as accordion-like sections where the liner material 24 is pleated
or folded over on itself, and is slightly biased in that position,
but readily and permanently unravels or opens to conform to an
aneurysm perimeter when exposed to minimal additional radial forces
from internal pressure (e.g., 0-5 ATM and illustratively 0-2 ATM or
1-2 ATM). Such forces can be generated, for example, by the
introduction of embolic coils or particles, liquid embolics, or
other embolic materials into the interior of aneurysm liner 24.
[0041] For example, FIG. 2D shows that expansion zone 36 has
totally expanded under increased internal pressure within liner 24.
FIG. 2D also illustrates that expansion zone 32 has expanded
partially, but expansion zone 34 remains unexpanded. This allows
liner 24 to expand in an asymmetrical, or irregular geometry to
fill the irregular lobe 38 of aneurysm sac 16. Catheter 20 is then
detached and removed, leaving aneurysm liner 24 in place within
aneurysm sac 16.
[0042] FIG. 2E illustrates another embodiment of treatment device
30, in which treatment device 30 has a plurality of perforations
therein. Of course, the perforations can be made mechanically or
through the use of laser drilling or any other desired mechanism or
method of forming perforations. The perforations provide for
efficient blood displacement in that they hold embolic material
within liner 24, but allow blood previously residing in aneurysm
sac 16 to exit through neck 18 as liner 24 is expanded to fill the
aneurysm sac 16.
[0043] FIGS. 3A and 3B illustrate another embodiment of an aneurysm
treatment device 50 in accordance with another embodiment of the
present invention. FIG. 3A shows treatment device 50 in the
collapsed, insertion position, while FIG. 3B shows it in the
deployed position, having embolic material delivered thereto. In
one illustrative embodiment, treatment device 50 includes an
aneurysm liner portion 52 supported by a network of expandable
struts 54. Struts 54 are illustratively super elastic alloys, such
as nickel titanium (Nitinol), or shape memory polymers, which are
connected to liner portion 52. While FIGS. 3A and 3B show struts 54
connected to the interior of liner portion 52, they could certainly
be connected to the exterior portion thereof, by braiding or
weaving them into the material of liner portion 52 or by utilizing
adhesive, stitching, or other bonding, etc.
[0044] FIG. 3A shows that, in the collapsed position, struts 54 are
substantially collapsed into a linear position, and they thus drive
collapse of liner portion 52 around them as well. In another
embodiment coils 21 and 22 can be used, as in previous embodiments,
to hold device 50 in its collapsed position. In this low profile
position, device 50 can be advanced into the aneurysm sac 16. In
one illustrative embodiment, device 50 is maintained in its
collapsed low profile position within a delivery catheter, or
confined by delivery wire 26. Delivery wire 26 is advanced such
that its distal tip is located within neck 18 of aneurysm sac 16.
Device 50 is then extended past the distal end of delivery wire 26
and struts 54 self deploy. In doing that, struts 54 expand
outwardly to the position shown in FIG. 3B, and thus deploy liner
portion 52 outwardly as well.
[0045] Embolic material is then introduced through catheter 20 and
through the interior of device 50. Since the distal portion of
struts 54 are not covered by liner material, the embolic material
being delivered occupies substantially the entire portion of
aneurysm sac 16, no matter how irregular in shape it may be. Once
the aneurysm sac 16 is filled with embolics, catheter 20 is
detached from device 50 and device 50 remains within aneurysm sac
16. FIGS. 3A and 3B also show that liner portion 52 can have
optional perforations therein to enhance the ability of blood to
flow from within aneurysm sac 16 as the aneurysm sac 16 is being
filled with embolic material. Such perforations are small enough to
inhibit the flow of embolic material from aneurysm sac 16 into
parent vessel 12. The distally located perforations may be larger
than those located proximally to facilitate distal permeation of
embolics, although this is optional.
[0046] FIGS. 4 and 5 illustrate additional embodiments of aneurysm
treatment devices 60 and 70, respectively. Device 60 is similar to
device 50 shown in FIGS. 3A and 3B, except that liner portion 52
extends to substantially cover struts 54. However, the distal end
of liner material 52 is provided with apertures that are of
sufficient size (or are distributed with sufficient density) to
allow embolic material to escape therethrough while the proximal
side of liner material 52 is provided with perforations which are
sufficiently small to retain the embolic material therein. For
example, spherical PVA embolics may traditionally be 500 microns in
size and may be used to fill a conventional aneurysm liner. The
distal portion of device 60 can thus be perforated with 750 micron
holes whereas the proximal portion near the neck 18 of aneurysm sac
16 can illustratively be perforated with 350 micron sized,
irregularly distributed, holes. Therefore, as the embolics are
introduced into liner portion 52, they are sized to be able to
escape the distal end thereof and or occupy the irregular spaces in
the aneurysm sac 16, without escaping back into the parent vessel
12.
[0047] It should also be noted that the embodiments shown in FIGS.
3A-5 need not include separate struts but can instead be formed of
the liner material which is simply thicker, harder or coated with a
stiffer material. Similarly, if struts are used, they can be formed
of a relatively stiff fabric material as well.
[0048] The device 70 in FIG. 5 is similar to device 60 in FIG. 4,
except that liner portion 52 is actually formed of two portions, a
proximal portion 72 and a distal portion 74, which are formed of
materials having different characteristics from one another.
Proximal portion 72 has material properties that allow permeation
of blood therethrough, but not embolics. However, distal portion 74
has material properties that allow permeation of both blood and
embolics therethrough. This allows the embolic materials, once
introduced through catheter 20, to escape through distal liner
portion 74 into the irregularly shaped lobes of the aneurysm sac
16. It also allows blood to exit the aneurysm sac 16 into the
parent vessel, without also allowing the embolics to escape.
[0049] In one embodiment, the properties of proximal portion 72
physically obstruct passage of embolics therethrough. For example,
portions 72 and 74 can be provided with holes of the same size.
However, when portions 72 and 74 are wet with embolics, portion 72
illustratively swells to reduce the size of holes therein (or
portion 74 shrinks to increase the size or the holes therein) so
that blood can flow through both portions 72 and 74 but embolics
can only pass through distal portion 74. The hole sizes can also be
controlled using coatings. Coatings on different portions 72 and 74
can swell at different rates. Similarly, if the liner portions 72
and 74 are formed of braided material, the size of the holes can be
controlled by the thickness of coatings used to coat the braid
material. The hole size can also be controlled based on the braided
pitch and tightness etc . . .
[0050] It should also be noted that the embodiments shown in FIGS.
4 and 5 can be made using struts that do not self-deploy, or using
no struts at all. In such an embodiment, the liner is expanded (or
deployed) merely by introducing embolics therein.
[0051] FIGS. 6A-6D illustrate further embodiments in accordance
with the present invention. FIGS. 6A and 6B show an aneurysm
treatment device 80 attached to a catheter 20, much as the previous
embodiments have been attached. FIGS. 6C and 6D show treatment
device 80 attached to a guidewire. Device 80 is formed of a shape
memory polymer that is weaved or braided to an appropriate mesh
density. Such shape memory polymers can tolerate up to 300-500
percent elastic deformation.
[0052] In use, the shape memory polymer, once weaved or braided to
its desired conformation, is cooled and compressed to its low
profile position shown in FIGS. 6A and 6C. Once the device 80 is
positioned within aneurysm sac 16 (as shown in FIGS. 6B and 6D) a
warm bolus of fluid, such as saline, is injected to locally heat
the environment of device 80. This increase in temperature causes
the shape memory polymer to assume its relaxed shape, such as a
sphere or other weaved or braided shape shown in FIGS. 6B or 6D.
Because the shape memory polymers allow up to 300-500 percent
elastic deformation, the expansion ratio (between its constrained
and relaxed sizes) allows the device to be collapsed down to a
small enough configuration to easily be manipulated within the
vasculature, but to still be expanded sufficiently to fill fairly
large aneurysms, even those in excess of 12 millimeters in
diameter.
[0053] It should also be noted that heating the environment can be
accomplished in any other desired way as well, such as maintaining
the shape memory polymer in a cooled state through injection of
cooled saline and then simply allowing body heat to warm the
device, or generating heat by any electrical, magnetic, chemical or
other means.
[0054] FIGS. 7A-7C illustrate yet another embodiment of an aneurysm
treatment device 90 in accordance with an embodiment of the present
invention. Treatment device 90 illustratively includes an aneurysm
neck bridge element, for example, formed of loops 92 of nickel
titanium or shape memory polymer material. The aneurysm neck bridge
includes, at its proximal end, a woven or braided shape memory
polymer liner section 94. The loops 92 are maintained in a low
profile (or constrained) position within a delivery catheter 96 for
delivery to the aneurysm treatment site.
[0055] In one illustrative embodiment, loops 92 are held in the
constrained position by compressing shape memory polymer 94 into a
constrained position. Then, device 90 is advanced through delivery
catheter 96 into the aneurysm sac 16. After it has been advanced
into the aneurysm sac, a warm bolus of fluid, such as saline, is
injected through delivery catheter 96 to warm the local environment
of shape memory polymer 94. This causes shape memory polymer 94 to
assume its relaxed position allowing loops 92 to open into the neck
bridging position shown in FIG. 7B. Because the loops 92 are held
in their low profile position by the shape memory polymer material
94 during delivery, this reduces the tendency of the loops to "pop"
or "spring" open and thus reduces the friction within catheter 96,
and enhances the ability to place the device quickly and
accurately. Device 90 can be placed in neck 18 and embolics can be
delivered through catheter 96. FIG. 7C shows that aneurysm sac 16
can also be filled with embolics through a separate catheter 93
placed through mesh 94.
[0056] FIGS. 8A and 8B illustrate yet another embodiment of a
treatment device (or liner) 100 in accordance with the present
invention. FIG. 8A shows device 100 in its collapsed, delivery
position while FIG. 8B shows device 100 in its deployed position.
Treatment device 100 is formed of two different types of material
at desired locations, based on the properties of the material. The
composite treatment device 100 is constructed, illustratively, of
an expandable fabric liner type material 102 which forms the bodice
of liner 100 and a polymer material such as wound urethane which
forms the ends or poles of liner 100. The fabric type material is
illustratively a material that is suitable for creating a spun,
wound, mesh, weave or braided fabric, such as nylon, polyethylene,
polypropylene, polyglycolic acid material, polylactic acid
material, etc.
[0057] Due to the excessive volume created by gathering such
materials to create the poles 104 and 106 of device 100, these
areas are illustratively constructed from thinner material that can
be material pre-shaped into three dimensional forms. Such materials
can include, for example, polymers such as urethane, which is
flowable over the ends of bodice portion 102 to form the poles
thereof. To form the poles, the bodice can be formed, or placed,
over a mandrel and the pole material is flowed thereover or form a
sandwich thereabout. The pole material can also be placed over
marker pole coils to enhance manufacturability and
fluoro-visibility. This eliminates the need to gather the bodice
material and form pleats, which yields an undesirably large
volume.
[0058] FIGS. 9A-9C illustrate yet another embodiment of the present
invention. FIG. 9A is a side, partial sectional view of a treatment
device 200. It should be noted that while device 200 is shown over
a guidewire 26, it need not be delivered over a guidewire but can
be delivered using any technique suitable to the task. Device 200
includes a liner portion 202, and a detachment zone 204. The
detachment zone 204 is connected to a proximal catheter 206 which
can optionally be delivered within a delivery catheter 208 or by
wire 26 alone. Within liner portion 202 is a coil 210. Coil 210
has, received therein, a folded section 212 of liner portion 202.
In other words, the distal portion of liner 202 is tucked within,
and frictionally retained within, coil 210.
[0059] FIG. 9B shows device 200 being deployed within an aneurysm
16 that has a distal lobe 214. In an initial stage of deployment,
device 200 is placed within aneurysm 16, across neck 18. Embolic
material is then inserted into liner portion 202 which causes it to
move radially outwardly to fill the outer sides of aneurysm 16.
However, this still leaves the distal lobe 214 of aneurysm 16
unfilled. Continued pressure within liner portion 202, (by the
introduction of additional embolics, for instance) causes folded
portion 212 to unfold distally, or to move in the direction
indicated by arrow 216, out from within coil 210.
[0060] This adds additional axial length to device 200 such that it
can better fill the distal lobe 214 of aneurysm 16. This is better
illustrated in FIG. 9C. It can be seen in FIG. 9C that a majority
of the folded portion 212 has now unfolded to become exposed to the
aneurysm wall and thus fill distal lobe 214 of aneurysm 16.
[0061] Coil 210 can illustratively simply be a floating coil,
within liner portion 202, having portion 212 folded or tucked in
its interior such that it frictionally engages and lightly holds
folded portion 212 within its interior until the force of embolics
introduced into liner portion 202 causes portion 212 to unfold in
the distal direction. Alternatively, coil 210 can be adhesively
engaged to the surface of folded portion 212, with a weak adhesive
that dissolves or can be broken simply by the force of introducing
embolic material into liner portion 202.
[0062] Once device 200 is deployed within aneurysm 16, it is
detached at detachment zone 204 using any suitable detachment
technique and the remainder of the system is withdrawn from the
vasculature.
[0063] FIGS. 10A-10D illustrate another embodiment of the present
invention. FIG. 10A illustrates a treatment device 250 for
deployment in an aneurysm. Device 250 includes a catheter portion
252 and an aneurysm liner portion 254. In one illustrative
embodiment, liner portion 254 is configured to expand radially, but
to shrink axially, when internal pressure is created through, for
example, the introduction of embolics therein. Thus, device 250 may
be suitable to treating wide neck aneurysms. Liner portion 254 is
illustratively attached to catheter 252 at detachment zone 256.
[0064] In one illustrative embodiment, liner portion 254 is
constructed of a highly linear porous polymer such as ePTFE. The
orientation of the polymer chain in liner portion 254 is along the
length of the device as indicated by arrow 258. This orientation
configures device 250 to distend radially as coils or other
embolics are introduced into the liner portion 254. This radial
expansion results in the device shrinking axially.
[0065] For example, FIG. 10B shows device 250 deployed within
aneurysm 16. Embolics (such as coils 260) are being introduced into
liner portion 254. It can be seen that liner portion 254 begins to
expand radially in the direction indicated by arrows 262 and beings
to shrink axially.
[0066] FIG. 10C illustrates further deployment of device 250 within
aneurysm 16. Continued introduction of embolic material 260 within
liner portion 254 causes a continued increase in the radial
dimension of liner portion 254 and a continued reduction in the
axial dimension of liner portion 254. Once liner portion 254 is
filled to a desired extent with embolic material, it has expanded
radially to such a dimension to bridge neck 18 of aneurysm 16. This
is better indicated in FIG. 10D. Liner portion 254 is then detached
from catheter 252 at detachment zone 256 and the remainder of the
system is withdrawn from the vasculature. Of course, it should be
noted that an additional microcatheter or other delivery device can
be inserted into aneurysm 16 either prior to, or after deployment
of liner portion 254. Additional embolics can be introduced distal
of liner portion 254 to completely fill the aneurysm.
[0067] FIG. 10E shows device 250 deployed in a small neck aneurysm.
It can be seen that device 250 may be particularly well suited to
this type of aneurysm as it easily seals the neck 18.
[0068] It should also be noted, of course, that the embodiments
shown in FIGS. 9A-10D can be provided with features of the other
embodiments as well, such as perforations, internal deployment
coils, expansion zones, different elasticity materials, etc.
[0069] It should further be noted that all of the embodiments
discussed herein can optionally have biodegradable, cell growth
enhancing material such as polyglycolic acid (PGA) or polylactic
acid (PLA) disposed thereon in a region that will illustratively be
deployed in a neck region of the aneurysm. Of course, other
material or combinations of these materials may be used as
well.
[0070] It can thus be seen that the present invention provides a
number of different embodiments for treating aneurysms. These
embodiments address many of the various deficiencies and
disadvantages associated with prior aneurysm treatment devices.
[0071] Although the present invention has been described with
reference to illustrative embodiments, workers skilled in the art
will recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention.
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