U.S. patent application number 11/384999 was filed with the patent office on 2006-07-20 for tubular prosthesis for external agent delivery.
This patent application is currently assigned to Scimed Life Systems, Inc.. Invention is credited to John E. Sherry.
Application Number | 20060161247 11/384999 |
Document ID | / |
Family ID | 25526588 |
Filed Date | 2006-07-20 |
United States Patent
Application |
20060161247 |
Kind Code |
A1 |
Sherry; John E. |
July 20, 2006 |
Tubular prosthesis for external agent delivery
Abstract
A tubular prosthesis, which may be an endovascular prothesis, is
provided which includes a tubular member (stent or stent/graft
combination) and an outer covering having portions sealed to the
tubular member. The tubular member is impervious to a
pre-determined fluid, particularly an occluding fluid, while the
outer cover is pervious to the pre-determined fluid. In one aspect
of the present invention, the implantation of the prosthesis allows
for occluding fluid to weep from the prosthesis and into a sac of
an aneurysm to cause occlusion thereof without introducing the
occluding fluid into the blood stream. In this manner, a Type II
failure of the prosthesis may be avoided. In other aspects of the
invention, therapeutic agents may be delivered and/or a seal may be
formed about the prosthesis to prevent a Type I failure.
Inventors: |
Sherry; John E.; (Needham,
MA) |
Correspondence
Address: |
HOFFMANN & BARON, LLP
6900 JERICHO TURNPIKE
SYOSSET
NY
11791
US
|
Assignee: |
Scimed Life Systems, Inc.
|
Family ID: |
25526588 |
Appl. No.: |
11/384999 |
Filed: |
March 20, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09978988 |
Oct 16, 2001 |
7033389 |
|
|
11384999 |
Mar 20, 2006 |
|
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Current U.S.
Class: |
623/1.44 |
Current CPC
Class: |
A61F 2/07 20130101; A61F
2250/0067 20130101; A61F 2002/065 20130101; A61F 2250/0003
20130101; A61F 2/89 20130101; A61F 2250/0068 20130101 |
Class at
Publication: |
623/001.44 |
International
Class: |
A61F 2/06 20060101
A61F002/06 |
Claims
1. A method of occluding a sac of an aneurysm, the method
comprising the steps of: implanting endovascularly an endovascular
prosthesis which by-passes the aneurysm, said endovascular
prosthesis including a tubular member having a wall, said wall
being impervious to transmission therethrough of an occluding
fluid, and an outer covering having portions sealed to said tubular
member, said outer covering being pervious to transmission
therethrough of said occluding fluid; and conveying a dose of
occluding fluid into a pocket at least partially defined between
said tubular member and said outer covering, said dose being an
effective amount to at least partially occlude the sac of the
aneurysm, whereby said occluding fluid transmits through said outer
covering to at least partially occlude the sac of the aneurysm.
2. A method as in claim 1 further comprising the step of placing a
fluid conduit into fluid communication with said pocket.
3. A method as in claim 2, wherein the step of conveying a dose of
occluding fluid includes conveying said occluding fluid via said
fluid conduit.
4. A method as in claim 2, wherein the step of placing a fluid
conduit is performed before the step of implanting
endovascularly.
5. A method as in claim 4, further comprising the step of detaching
said fluid conduit from said endovascular prosthesis after the step
of conveying a dose of occluding fluid.
6. A method as in claim 1, wherein said occluding fluid is an
embolic liquid selected from the group consisting of alginates,
hyaluronic acid, cyanoacrylates, and admixtures thereof.
7. A method as in claim 1, wherein said occluding fluid is selected
from the group consisting of sclerosing agents, polyurethanes,
silicones, and admixtures thereof.
8. A method as in claim 1, wherein said occluding fluid includes
thrombin.
9. A method as in claim 1, wherein said occluding fluid includes an
autologous clot.
10. A method of forming an endovascular prosthesis, the method
comprising the steps of: providing a tubular member which includes
a wall, said wall being impervious to transmission therethrough of
a pre-determined fluid; and sealing portions of an outer covering
to said tubular member, said outer covering being pervious to
transmission therethrough of said pre-determined fluid.
11. A method as in claim 10, further comprising the step of placing
a fluid conduit in direct fluid communication with a pocket at
least partially defined between said tubular member and said outer
covering.
12. A method as in claim 10, further comprising the step of placing
a fluid conduit in indirect fluid communication with a pocket at
least partially defined between said tubular member and said outer
covering.
13. A method as in claim 12, wherein the step of placing a fluid
conduit includes mounting a valve in fluid communication with said
pocket, and connecting said fluid conduit to said valve.
14. A method as in claim 10, further comprising the step of making
said outer covering be pervious to transmission therethrough of
said pre-determined fluid.
15. A method as in claim 14, wherein the step of making includes
cutting apertures in said outer covering.
16. A method as in claim 14, wherein the step of making includes
forming said outer covering with porosity.
17. A method as in claim 10, wherein the step of sealing includes
fusing portions of said outer covering to said tubular member.
18. A method as in claim 10, wherein the step of sealing includes
bonding portions of said outer covering to said tubular member.
19. A method of administering a therapeutic agent, the method
comprising the steps of: implanting a tubular prosthesis, said
prosthesis including a tubular member having a wall, said wall
being impervious to transmission therethrough of a pre-determined
therapeutic agent, and an outer covering having portions sealed to
said tubular member, said outer covering being pervious to
transmission therethrough of said pre-determined therapeutic agent;
and conveying a dose of said pre-determined therapeutic agent into
a pocket at least partially defined between said tubular member and
said outer covering.
20. A method as in claim 19, further comprising the step of placing
a fluid conduit into fluid communication with said pocket.
21. A method as in claim 20, wherein the step of conveying a dose
of pre-determined therapeutic agent includes conveying said
pre-determined therapeutic agent via said fluid conduit.
22. A method as in claim 20, wherein the step of placing a fluid
conduit is performed before the step of implanting
endovascularly.
23. A method as in claim 22, further comprising the step of
detaching said fluid conduit from said prosthesis after the step of
conveying a dose of pre-determined therapeutic agent.
24. A method of at least partially forming a seal between a tubular
prosthesis and a bodily passageway, the method comprising the steps
of: implanting a tubular prosthesis into a bodily passageway, said
prosthesis including a tubular member having a wall, said wall
being impervious to transmission therethrough of an occluding
fluid, and an outer covering having portions sealed to said tubular
member, said outer covering being pervious to transmission
therethrough of said occluding fluid; and conveying a dose of
occluding fluid into a pocket at least partially defined between
said tubular member and said outer covering, said dose being an
effective amount to at least partially occlude an area about said
tubular member so as to at least partially form a seal between said
prosthesis and portions of the bodily passageway.
25. A method as in claim 24, wherein said occluding fluid is an
embolic liquid selected from the group consisting of alginates,
hyaluronic acid, cyanoacrylates, and admixtures thereof.
26. A method as in claim 24, wherein said occluding fluid is
selected from the group consisting of sclerosing agents,
polyurethanes, silicones, and admixtures thereof.
27. A method as in claim 24, wherein said occluding fluid includes
thrombin.
28. A method as in claim 24, wherein said occluding fluid includes
an autologous clot.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional application of U.S.
application Ser. No. 09/978,988, filed on Oct. 16, 2001, now
allowed, the entire contents of which are hereby incorporated by
reference.
FIELD OF THE INVENTION
[0002] This invention relates to tubular prostheses, including, but
not limited to, endovascular grafts and stent/grafts, for
maintaining patency of blood vessels and treating aortic artery
aneurysms, and tubular conduits for maintaining patency in other
bodily passageways.
BACKGROUND OF THE PRIOR ART
[0003] It is known in the prior art to use endovascular prostheses
to treat aortic artery aneurysms ("AAA"). Such treatment includes
implanting a stent, or stent/graft, within the diseased vessel to
by-pass the anomaly. An aneurysm is a sac formed by the dilation of
the wall of the artery, which may be congenital, but usually is
caused by disease and, occasionally, by trauma. With reference to
FIG. 1, sac 1 of aneurysm A is defined by dilated portions 2 of
aortic artery AA. With the collection of blood and other embolic
material in the sac 1, and being subjected to hemodynamic pressure,
the aneurysm A may rupture, if untreated, causing internal
bleeding.
[0004] Techniques had been developed in the prior art where
diseased portions of a blood vessel, such as with an aneurysm, were
ablated and replaced with a prosthetic member, such as that shown
in U.S. Pat. No. 4,938,740 to Melbin. This technique, however,
required open surgery. As an improvement over this technique,
endovascular emplacement techniques have been developed to implant
grafts and stent/grafts into a vessel from a remote puncture site,
thereby obviating the need for open surgery. For example, as shown
in FIG. 1, an endovascular prosthesis 3 (stent or stent/graft) is
positioned to by-pass the aneurysm A with ends 4, 5 of the
prosthesis being in contiguous contact with healthy portions of the
aortic artery AA, the prosthesis 3 having been introduced
endovascularly (e.g. with a catheter). Accordingly, if the aneurysm
A was to rupture, blood flow through the aortic artery AA would be
uninterrupted, and internal bleeding generally avoided.
[0005] Although considerable success has been enjoyed with stent
and stent/graft performance, failures have been noted and
predominantly classified in four classes: Types I-IV. Type I
failures relate to leaks (referred to as endoleaks) between the
vascular prosthesis and the vessel wall. For example, with
reference to FIG. 1, a Type I failure would be blood weeping about
the end 4 of the prosthesis 3 into the sac 1.
[0006] A Type II failure involves blood flowing into the aneurysm
sac through collateral arteries. Again, with reference to FIG. 1,
the sac 1 may be in fluid communication with blood vessels BV,
other than the aortic artery AA. Typically, lumbar arteries are in
fluid communication (directly or indirectly) with an aneurysm sac.
Because blood flow out of the sac 1 is prevented, hemodynamic
pressure away from the sac 1 is not present. However, because of
hemodynamic pressure within blood vessels in communication with the
sac 1, blood flow, nevertheless, is directed into the sac 1 (as
shown by arrows). A technique has been developed in the prior art
which calls for embolizing the blood vessels BV, such as with
embolus coils, thereby isolating the sac 1 from collateral blood
flow. However, an additional procedure would be required for
embolization.
[0007] A Type III failure is a mechanical failure, wherein a hole
may be ripped into the prosthesis (e.g., excessive wear at a
metal/non-metal (fabric or polymer) interface) or poor integrity
exists at a connection, or connections, between modular components
of a prosthesis, (e.g., extensions may be connected to the
prosthesis to obtain improved securement in one or both of the
iliac arteries.) For example, as shown in FIG. 1, a hole 6 may be
torn into the prosthesis 2, or poor sealing is obtained at the
connection between the prosthesis 3 and an extension 7.
[0008] A Type IV failure relates to excessive prosthesis porosity,
wherein blood seeps through the prosthesis regardless of the
integrity of sealing and mechanical connections.
[0009] As can be readily appreciated, even with the successful
implantation of an endovascular prosthesis, failures may occur
thereafter. It has been found that Type II failures are most
prevalent, and may effect up to 30% of all implanted prostheses.
Accordingly, there is a clear need for an endovascular prosthesis
which can reduce the likelihood, and ideally eliminate, Type II
failures.
SUMMARY OF THE INVENTION
[0010] To overcome deficiencies in the prior art, a tubular
prosthesis is provided that includes a tubular member, which is
impervious to a pre-determined fluid, and an outer covering, which
is pervious to the pre-determined fluid. Accordingly, in one aspect
of the invention, the prosthesis may be an endovascular prosthesis,
and a fluid, which is effective for occluding the sac of an
aneurysm, may be introduced by the prosthesis into a space between
the tubular member and the outer covering. The fluid will transmit
through the outer covering and weep into the sac to cause at least
partial occlusion thereof without the occluding fluid being
introduced into the blood stream. In this manner, collateral blood
flow may be prevented from flowing into the aneurysm sac and
collecting therein.
[0011] A fluid conduit, preferably a microcatheter, is connected to
the endovascular prosthesis so as to be in fluid communication with
the space defined between the tubular member and the outer
covering. It is preferred that the fluid conduit be connected to
the prosthesis prior to introduction into the body, with such
connection continuing through deployment of the prosthesis and
engagement with the vessel. Prior to withdrawal of the deployment
device used to implant the prosthesis (e.g. an introducer
catheter), occluding fluid is injected through the fluid conduit
and between the tubular member and the outer cover with an
effective amount of fluid being introduced to achieve at least
partial occlusion of the aneurysm sac. With the outer cover being
pervious to the fluid, the fluid transmits therethrough. Upon the
effective dose having been injected into the space, the fluid
conduit is caused to detach from the prosthesis, and withdrawn with
any deployment device, such as a guidewire.
[0012] The tubular member may be of any endovascular prosthetic
construction known in the prior art, including graft and
stent/graft configurations (including single layer and multi-layer
grafts and stent/grafts). The tubular member may be a textile
graft, a polymeric graft, or a combination thereof. In addition,
the tubular member may have a stent reinforcement (single stent or
multiple stents), such stent being self-expanding or expandable by
a distensible member, such as a balloon.
[0013] The outer covering may be formed of a textile, a polymeric
film, or a combination thereof. In addition, the outer covering may
be made pervious to the occluding fluid through inherent porosity
of the constituent material of the outer covering (e.g., porosity
of expanded polytetrafluoroethylene (ePTFE)), and/or, more
preferably, through cut apertures physically defined in the outer
covering. To attempt to achieve even distribution of the occluding
fluid, it is desired to make the outer covering increasingly
pervious to the fluid at locations further from the fluid
conduit.
[0014] The occluding fluid is preferably a liquid embolic, which
may be an alginate, an hyaluronic acid, and/or a cyanoacrylate, or
an admixture thereof. Alternatively, a sclerosing agent may be
used, as well as cross-linking polymers (polyurethanes, silicones),
thrombin, and autologous clot(s). The occluding fluid may be in a
liquid state or a gel, and may be formed with solids in a
suspension of either state (liquid or gel).
[0015] In another aspect of the invention, therapeutic agents, with
or without the occluding fluid, may be transmitted via the subject
invention.
[0016] The tubular prosthesis may be used as an endovascular
prosthesis, as well as, in other applications to maintain patency
of a bodily passageway, such as the esophagus, trachea, colon,
biliary tract, urinary tract, prostate, and brain.
[0017] These and other features of the invention would be better
understood through a study of the following detailed description
and accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0018] FIG. 1 is a schematic of an aortic artery aneurysm with an
endovascular prosthesis by-passing thereby;
[0019] FIG. 2 shows a first embodiment of a tubular prosthesis of
the subject invention;
[0020] FIG. 3 shows a tubular member for use with the first
embodiment of the subject invention;
[0021] FIG. 4 shows a second embodiment of a tubular prosthesis of
the subject invention;
[0022] FIG. 5 shows a bifurcated Y-shaped tubular member for use
with the second embodiment of the subject invention; and
[0023] FIGS. 6A and 6B are schematics depicting the connections of
a fluid conduit to the prosthesis.
DETAILED DESCRIPTION OF THE INVENTION
[0024] With reference to FIGS. 2 and 4, first and second
embodiments of a prosthesis 10 are respectively depicted therein.
Reference will be made herein to the prosthesis being endovascular,
although as pointed out above, the prosthesis may be used in other
applications. In each embodiment, the endovascular prosthesis 10
includes a tubular member 12, 12a and an outer covering 14. The
tubular member 12, 12a is impervious to the transmission
therethrough of a pre-determined fluid, particularly an occluding
fluid, while the outer covering 14 is pervious to the transmission
therethrough of the pre-determined fluid. Accordingly, the
prosthesis 10 can be utilized to at least partially occlude the sac
of an aneurysm, as described below. The endovascular prosthesis 10
may take any shape or form as required, although commonly, the
prosthesis 10 will have a cylindrical shape (as shown in FIG. 2),
or a bifurcated Y-shape (as shown in FIG. 4). Although only these
two shapes are shown, other shapes are possible.
[0025] The tubular member 12, 12a may be of any endovascular
prosthetic construction known in the prior art, including graft and
stent/graft configurations. With reference to FIG. 3, in the first
embodiment, the tubular member 12 has a cylindrical shape with a
tubular wall 16 having an outer surface 18 and an inner surface 20
defining a single lumen 22. The tubular member 12 need not be
formed as a right cylinder, and may be irregularly formed (e.g.
bent; eccentric). In a second embodiment, as shown in FIG. 5, the
tubular member 12a has a bifurcated Y-shape with a first tubular
portion 16a, defining a lumen 22a, from which extend branches 24a,
24b, each defining a lumen 26 in fluid communication with the lumen
22a. As is readily apparent, the tubular member 12, 12a defines the
general shape of the endovascular prosthesis 10, and thus, the
tubular member 12, 12a is formed to any desired shape of the
endovascular prosthesis 10.
[0026] The tubular member 12, 12a may be a textile graft, a
polymeric graft, or a combination thereof (including single layer
and multi-layer configurations). In addition, the tubular member
12, 12a may have a stent reinforcement, such stent being
self-expanding or expandable by a distensible member, such as a
balloon (stents S are shown in FIG. 5) (a single stent or multiple
stents may be used). Graft and stent/graft designs are well known
in the art, and any design compatible with the invention may be
used. The tubular member 12, 12a is shown in each embodiment as a
unitary member, regardless of shape. As an alternative, the tubular
member 12, 12a may be formed from modular components and/or have
the shape as shown, but connected to extensions as known in the
prior art (e.g. the extension 7 shown in FIG. 1).
[0027] The outer covering 14 is disposed on, and preferably sealed
to, portions of the outer surface of the tubular member 12, 12a. In
a preferred embodiment, as shown in FIGS. 2 and 4, the outer
covering 14 is generally coextensive with the tubular member 12,
12a. The outer covering 27 is sealed to the tubular member 14 using
any technique known to those skilled in the art, including, but not
limited to, fusing and bonding. Sealed portions 27 of the outer
covering 14 are preferably spaced-apart so that unsealed portions
of the outer covering 14 are bounded by the sealed portions 27. In
this manner, entrapped space between the tubular member 12, 12a and
the outer covering 14 which is at least partially bounded by the
sealed portions 27 of the outer covering 14 defines a pocket 15 for
receiving occluding fluid. Optionally, the outer covering 14 can be
sealed at multiple locations to define multiple pockets 15. Because
of the impervious nature of the tubular member 12, 12a and the
sealed portions 27, the fluid can only escape from the pocket 15
via transmission through the outer covering 14. As shown in FIG. 2,
it is preferred to seal the outer covering 14 at portions in
proximity to the ends 28 and 30 of the tubular member 12. With
respect to the tubular member 12a, as shown in FIG. 4, it is
preferred that the outer covering 14 have sealed portions 27 in
proximity to all ends 28a and 30a. Accordingly, the pocket 15 is
generally coextensive with the tubular member 12, 12a.
[0028] As a variation, the outer covering 14 may be formed as a
patch which covers only a portion of the tubular member 12, 12a, as
shown in dashed lines in FIG. 2. Although not shown, the outer
covering 14 may form an annular band about the tubular member 12,
12a. Furthermore, multiple outer coverings 14 may be used as
patches to form a discontinuous or regular pattern.
[0029] The outer covering 14 may be formed of a textile, a
polymeric film, or a combination thereof. The critical aspect of
the outer covering 14 is for it to be pervious to the occluding
fluid. The outer covering 14 may be made pervious through inherent
porosity of the constituent material of the outer covering, for
example due to the porosity of expanded polytetrafluoroethylene
(ePTFE). In addition, in a preferred manner of achieving the
pervious nature of the outer covering 14, cut apertures 32 may be
physically defined in the outer covering 14, as shown in FIG. 4. It
is also possible to combine these two approaches.
[0030] In a preferred embodiment, a fluid conduit 34, preferably a
microcatheter, is connected to the endovascular prosthesis 10 so as
to convey the occluding fluid thereto. With reference to FIGS. 6a
and 6b, the fluid conduit 34 may be in direct fluid communication
with the pocket 15, with an end 36 of the fluid conduit 34 being
located therein. As can be appreciated, to achieve this result, the
fluid conduit 34 must breach the sealed portions 27. This can be
readily done during manufacturing by causing the sealed portions 27
to be formed about the fluid conduit 34. However, upon removal of
the fluid conduit 34, an open passage will be defined through the
sealed portions 27. Thus, it is preferred to only use the technique
where inherent viscosity of the occluding fluid will prevent
leakage of the occluding fluid through the open passage.
[0031] As a preferred alternative, a valve 38 (preferably one-way)
is disposed in communication with the pocket 15, so that the fluid
conduit 34 is in indirect communication with the pocket 15 via the
valve 38. The construction of the valve 38 and the fluid conduit 34
may be the same as that used with silicone balloon distension,
(e.g., the system sold under the trademark "APOLLO" by Target
Therapeutics of Fremont, Calif.).
[0032] In a preferred embodiment, the fluid conduit 34 is connected
to the endovascular prosthesis 10 prior to insertion into the human
body. After deployment of the endovascular prosthesis 10, using any
technique and device known, the fluid conduit 34 preferably remains
connected to the prosthesis 10. It is envisioned that a Strecker
pull-string type deployment device or a pull-back sheath deployment
device would operate well with the subject invention. An effective
amount of occluding fluid is conveyed through the fluid conduit 34
into the pocket 15 to at least partially occlude the sac of the
aneurysm being treated. With the effective dose having been
conveyed, the fluid conduit 34 is caused to be detached, preferably
with a sufficiently strong pull of the fluid conduit 34. With the
aforementioned prior art silicone balloon distension systems,
minimum threshold forces have been developed to achieve such
detachment and it is contemplated herein to use similar methodology
to require minimum threshold forces for detachment. Once detached,
the fluid conduit 34 is removed with any other deployment devices,
such as an introducer catheter.
[0033] The occluding fluid is preferably a liquid embolic, which
may be an alginate, an hyaluronic acid, and/or a cyanoacrylate, or
an admixture thereof. Alternatively, a sclerosing agent may be
used, as well as cross-linking polymers (polyurethanes, silicones),
thrombin and autologous clot(s). The occluding fluid may be in a
liquid state or gel, and may be formed with solids in a suspension
of either state (liquid or gel).
[0034] With the occluding fluid being disposed within the pocket
15, the fluid may transmit through the outer covering 14 to at
least partially occlude the sac of the aneurysm being treated
without the fluid being introduced into the blood stream.
[0035] In another aspect of the invention, therapeutic agents, with
or without the occluding fluid, may be transmitted via the subject
invention in the same manner described with respect to the
occluding fluid, including: anti-thrombogenic agents (such as
heparin, heparin derivatives, urokinase, and PPack
(dextrophenylalanine proline arginine chloromethylketone);
anti-proliferative agents (such as enoxaprin, angiopeptin, or
monoclonal antibodies capable of blocking smooth muscle cell
proliferation, hirudin, and acetylsalicylic acid);
anti-inflammatory agents (such as dexamethasone, prednisolone,
corticosterone, budesonide, estrogen, sulfasalazine, and
mesalamine); antineoplastic/antiproliferative/anti-miotic agents
(such as paclitaxel, 5-fluorouracil, cisplatin, vinblastine,
vincristine, epothilones, endostatin, angiostatin and thymidine
kinase inhibitors); anesthetic agents (such as lidocaine,
bupivacaine, and ropivacaine); anti-coagulants (such as
D-Phe-Pro-Arg chloromethyl keton, an RGD peptide-containing
compound, heparin, antithrombin compounds, platelet receptor
antagonists, anti-thrombin antibodies, anti-platelet receptor
antibodies, aspirin, prostaglandin inhibitors, platelet inhibitors
and tick antiplatelet peptides); vascular cell growth promotors
(such as growth factor inhibitors, growth factor receptor
antagonists, transcriptional activators, and translational
promotors); vascular cell growth inhibitors (such as growth factor
inhibitors, growth factor receptor antagonists, transcriptional
repressors, translational repressors, replication inhibitors,
inhibitory antibodies, antibodies directed against growth factors,
bifunctional molecules consisting of a growth factor and a
cytotoxin, bifunctional molecules consisting of an antibody and a
cytotoxin); cholesterol-lowering agents; vasodilating agents; and
agents which interfere with endogenous vascoactive mechanisms.
[0036] In a further aspect of the subject invention, the occluding
fluid may be introduced via the endovascular prosthesis 10 between
the blood vessel wall and the endovascular prosthesis 10 so as to
at least partially seal against endoleaks about the prosthesis 10
(i.e., Type I failure). (With other applications of the subject
invention, the occluding fluid is disposed between the wall of the
bodily passageway and the prostheis 10.) The occluding fluid may
create a blood-vessel seal (in whole or in part) with or without
occluding the sac of the aneurysm. Preferably, a ring-shaped pocket
15 may be provided in proximity to an end of endovascular
prosthesis 10 through which the occluding fluid may be delivered to
form the seal; as such, an annular seal may be desirably defined
about the prosthesis 10 in proximity to an end so as to restrict
endoleaks. The ability to seal against endoleaks is particularly
desirable where a blood vessel has an irregularly formed blood
vessel.
[0037] In a further enhancement of the invention, it is preferred
that the outer covering 14 be increasingly pervious to the
occluding fluid and/or therapeutic agents at further distances from
the fluid conduit 34. For example, with reference to FIG. 4, the
cut apertures 32 are formed increasingly larger further from the
fluid conduit 35 (i.e., as approaching the end 28A) and/or an
increasingly greater number of cut apertures 32 is provided further
from the fluid conduit 34 (i.e., the density of cut apertures 32
increases with distance from the fluid conduit 34) to provide less
resistance to the distribution of the occluding fluid and/or
therapeutics being conveyed via the fluid conduit 34. Likewise, the
cut apertures 32 are formed increasingly larger and/or greater in
number as located further down the branch portion 24b, to which the
fluid conduit 34 is not attached. As an alternative, or as an
additional option, the porosity of the constituent material may be
gradually increased at further locations from the source of the
occluding fluid and/or therapeutic agents to also provide less
fluid resistance.
[0038] Various changes and modifications can be made to the present
invention. It is intended that all such changes and modifications
come within the scope of the invention as set forth in the
following claims.
* * * * *