U.S. patent application number 12/966852 was filed with the patent office on 2011-11-10 for filling structure for a graft system and methods of use.
This patent application is currently assigned to Nellix, Inc.. Invention is credited to Raj P. Ganpath, Anupama Karwa, Amy Lee, K.T. Venkateswara Rao.
Application Number | 20110276078 12/966852 |
Document ID | / |
Family ID | 44226769 |
Filed Date | 2011-11-10 |
United States Patent
Application |
20110276078 |
Kind Code |
A1 |
Rao; K.T. Venkateswara ; et
al. |
November 10, 2011 |
FILLING STRUCTURE FOR A GRAFT SYSTEM AND METHODS OF USE
Abstract
A system for treating an aneurysm includes a first double-walled
filling structure having an outer wall and an inner wall. The
filling structure is adapted to be filled with a hardenable fluid
filling medium so that the outer wall conforms to an inside surface
of the aneurysm and the inner wall forms a generally tubular lumen
to permit blood flow therethrough. The inner wall comprises a blood
contacting layer and a reinforcing layer. The reinforcing layer
prevents circumferential creep or elastic expansion of the
lumen.
Inventors: |
Rao; K.T. Venkateswara; (San
Jose, CA) ; Ganpath; Raj P.; (Chennai, IN) ;
Lee; Amy; (Sunnyvale, CA) ; Karwa; Anupama;
(San Francisco, CA) |
Assignee: |
Nellix, Inc.
Palo Alto
CA
|
Family ID: |
44226769 |
Appl. No.: |
12/966852 |
Filed: |
December 13, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61291279 |
Dec 30, 2009 |
|
|
|
Current U.S.
Class: |
606/194 |
Current CPC
Class: |
A61F 2002/075 20130101;
A61F 2/90 20130101; A61F 2230/0067 20130101; A61F 2002/077
20130101; A61F 2/07 20130101; A61F 2230/0008 20130101 |
Class at
Publication: |
606/194 |
International
Class: |
A61M 29/00 20060101
A61M029/00 |
Claims
1. A system for treating an aneurysm, said system comprising: a
first double-walled filling structure having an outer wall and an
inner wall, wherein the filling structure is adapted to be filled
with a hardenable fluid filling medium so that the outer wall
conforms to an inside surface of the aneurysm and the inner wall
forms a generally tubular lumen to permit blood flow therethrough,
and wherein the inner wall comprises a blood contacting layer and a
reinforcing layer, the reinforcing layer adapted to prevent
circumferential creep or elastic expansion of the lumen.
2. The system of claim 1, wherein the reinforcing layer comprises a
metal, textile, membrane, or polymer mesh.
3. The system of claim 1, wherein the reinforcing layer comprises
fibers or filaments circumferentially disposed around the
lumen.
4. The system of claim 1, wherein the reinforcing layer comprises
fibers or filaments disposed spirally around the lumen.
5. The system of claim 3, wherein the fibers or filaments comprise
a metal, a polymer, a membrane, or a textile.
6. The system of claim 1, wherein the reinforcing layer encircles
the inner lumen and is substantially noncompliant.
7. The system of claim 6, wherein the inner lumen has a
longitudinal length, and wherein the reinforcing layer has a
longitudinal length that is less than the longitudinal length of
the inner lumen.
8. The system of claim 7, wherein the inner lumen has proximal and
distal ends, and wherein the proximal and distal ends are
flared.
9. A system for treating an aneurysm, said system comprising: a
first double-walled filling structure having an outer wall and an
inner wall, wherein the filling structure is adapted to be filled
with a hardenable fluid filling medium so that the outer wall
conforms to an inside surface of the aneurysm and the inner wall
forms a generally tubular lumen to permit blood flow therethrough,
and wherein the inner wall is comprised of a material with
anisotropic stress properties oriented such that its greatest
tensile strength is circumferential.
10. A system for treating an aneurysm, said system comprising: a
first double-walled filling structure having an outer wall and an
inner wall, wherein the filling structure is adapted to be filled
with a hardenable fluid filling medium so that the outer wall
conforms to an inside surface of the aneurysm and the inner wall
forms a generally tubular lumen to permit blood flow, and wherein
the lumen has a first end and a second end opposite the first end,
and wherein a diameter at the first end or the second end is
greater than a diameter of the lumen at a point between the first
and the second ends.
11. A system for treating an aneurysm, said system comprising: a
first multi-walled filling structure having at least an outer wall
and an inner wall, wherein the filling structure is adapted to be
filled with a hardenable fluid filling medium so that the outer
wall conforms to an inside surface of the aneurysm and the inner
wall forms a generally tubular lumen to permit blood flow
therethrough, and wherein the filling structure comprises at least
one interior wall that divides the multi-walled filling structure
into at least a first compartment and a second compartment, each of
the compartments fillable with the hardenable fluid filling medium
or another filling medium.
12. The system of claim 11, further comprising a fill port in fluid
communication with the first compartment.
13. The system of claim 11, wherein the first compartment surrounds
the tubular lumen, and the second compartment surrounds the first
compartment.
14. The system of claim 11, wherein the first compartment is in
restricted fluid communication with the second compartment.
15. The system of claim 11, further comprising a first fill port in
fluid communication with the first compartment, and a second fill
port in fluid communication with the second compartment.
16. The system of claim 1, wherein the inner surface of the filling
structure is coated and modified to adhere with the filling
medium.
17. The system of claim 1, where the filling medium adheres to the
inner walls of the filling structure to maintain device shape over
time.
18. The system of claim 11, where the inner and outer compartments
are filled with filling media of varying mechanical properties to
withstand mechanical forces from blood flow and long-term aneurysm
remodeling.
19. A system for treating an aneurysm, said system comprising: a
first double-walled filling structure having a differential
functional construct including an toroidal outer surface with a
tubular inner lumen, wherein the filling structure is adapted to be
filled with a hardenable fluid filling medium so that the outer
surface wall conforms to an inside surface of the aneurysm and the
lumenal wall forms a generally tubular lumen to permit blood flow
therethrough, and wherein the lumenal wall withstands mechanical
forces from blood flow and long-term aneurismal remodeling.
20. A system for treating an aneurysm, said system comprising: a
first double-walled filling structure having an outer wall and an
inner wall, wherein the filling structure is adapted to be filled
with a hardenable fluid filling medium so that the outer wall
conforms to an inside surface of the aneurysm and the inner wall
forms a generally tubular lumen to permit blood flow therethrough,
and wherein the inner wall is comprised of a first material and the
outer wall is comprised of a second material that is different from
the first material, and wherein the inner wall material is adapted
to resist creep and expansion due to pulsatile blood flow, and the
outer wall is adapted to conform with the aneurismal sac.
21. A system for treating an aneurysm, said system comprising: a
first double-walled filling structure having an outer wall and an
inner wall, wherein the filling structure is adapted to be filled
with a hardenable fluid filling medium so that the outer wall
conforms to an inside surface of the aneurysm and the inner wall
forms a generally tubular lumen to permit blood flow therethrough,
and wherein the inner wall is has a first thickness and the outer
wall has a second thickness that is less than the first
thickness.
22. A method for treating an aneurysm, said method comprising:
providing a double-walled filling structure having an outer wall
and an inner wall; positioning the double-walled filling structure
adjacent the aneurysm; filling the filling structure with a
hardenable fluid filling medium so that the outer wall conforms to
an inside surface of the aneurysm and the inner wall forms a
generally tubular lumen to permit blood flow therethrough; and
constraining the lumen from creeping or elastically expanding due
to the blood flow through the lumen.
23. The method of claim 22, wherein the constraining step comprises
providing a reinforcing layer disposed at least partially around
the tubular lumen.
24. The method of claim 22, wherein the constraining step comprises
filling a compartment disposed at least partially around the
tubular lumen with the hardenable fluid filling medium.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] The present application is a non-provisional of, and claims
the benefit of U.S. Provisional Patent Application No. 61/291,279
(Attorney Docket No. 025925-004400US) filed Dec. 30, 2009, the
entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to medical systems
and methods for treatment. More particularly, the present invention
relates to apparatus and methods for treating aneurysms.
[0004] Previous patent applications have described an approach to
repairing an aneurysm by introducing a filling structure into the
aneurysm, supporting the structure with a support structure, and
filling the filling structure with a hardenable material that fills
the aneurysm sac. Removing the support structure leaves a lumen for
blood flow, and the hardenable material fills the sac and prevents
blood pressure from enlarging it further.
[0005] Once it is placed into service, the filling structure
experiences pulsatile pressure, and by design shields the aneurysm
from most of this pressure. As a result, the aneurysm itself may
change shape by reabsorption of thrombus between the filling
structure and the artery wall, and shrinkage or remodeling of the
artery wall itself. This may result in reduced pressure on the
exterior of the filling structure. In some designs this may cause
the inner lumen of the filling structure to grow through
time-dependent elastic deformation or creep. It is desirable to
prevent this change in the inner lumen as the aneurysm changes
shape.
[0006] Aneurysms can occur in a range of shapes and sizes depending
on the individual anatomy of the affected artery, the length of
time it took to detect the aneurysm, blood pressure, and other
factors. As a result, structures designed to repair aneurysms by
filling the aneurism sac must either be designed to be effective
across a range of sac shapes and sizes, or they must be supplied in
multiple stock sizes, or they must be custom-made for a specific
anatomy. Sometimes, the structures may have a combination of the
aforementioned properties.
[0007] A promising class of intraluminal aneurysm repair devices
employs a double walled filling structure to fill the aneurysm sac
while maintaining a lumen for continued blood flow in the artery.
In order to accommodate a range of aneurysm sizes, the double
walled filling structure may be chosen such that it is capable of
expanding to at least the size of the sac in all parts of the
aneurysm. This obviates the need to make a custom version of the
device for each aneurysm, and instead allows the surgeon to choose
among a limited number of stock sized devices. In this case the
filling structure is selected to be at least as large as the sac to
be filled. Some embodiments may have an elastic outer wall that
expands and conforms to the inner aneurysm wall, while other
filling structures use a substantially inelastic outer wall that is
thin and flexible so that as the filling structure is filled, the
outer wall expands partially to completely fill the sac, and any
remaining capacity takes the form of wrinkles or pleats in the
outer wall of the filling structure. An advantage of the elastic
outer wall is the potential absence of wrinkles, but a drawback is
that an elastic outer wall will not conform exactly to abrupt
changes in curvature of the sac.
[0008] When the device is deployed and filled with hardened filling
medium, pressure on the aneurysm wall is relieved. Over time,
thrombus in the aneurysm is reabsorbed and the aneurysm wall
slackens, relieving counterpressure on the filling structure.
Therefore, the filling structure and filling medium needs to be
stiff enough that its internal lumen does not change shape as this
happens. Discontinuities in the filling medium caused by wrinkles
and pleats on the walls of the filling structure reduce the
strength of the filled structure. It would be advantageous to have
a filling structure that can be filled in such a way that no
internal wrinkles remain in some of its parts. It would also be
advantageous to have a filling structure that is strong enough to
resist creep even in the absence of an uninterrupted fill, yet
still be thin enough to be percutaneously deliverable through the
vasculature, which typically requires a 14 Fr or less device.
[0009] In addition, it would also be desirable to have a filling
medium with a chemistry that also adheres to walls of the filling
structure during or after curing, so that the in-situ formed device
can withstand the biomechanical loads and accommodate long-term
remodeling of the aneurysm. This can be accomplished through
additives thereby modifying the chemistry of the filling medium or
modifying the chemistry or coating the inner layers of the filling
structure so that filling medium adheres to the filling structure
as the device forms in-situ.
[0010] In order to avoid device migration and leakage, it is also
desirable that the device, when filled with hardened filling
material, conform as closely as possible to the shape of the
aneurysm at its proximal and distal ends. It is also desirable to
provide means by which the filling structure may be made to conform
closely to the necks of the aneurysm, while being made of a thin,
inelastic material. It is also desirable to resist creep
deformation and remodeling caused by the pulsatile pressure of
blood against the device.
[0011] 2. Description of the Background Art
[0012] U.S. Patent Publication No. 2006/0025853 describes a
double-walled filling structure for treating aortic and other
aneurysms. Copending, commonly owned U.S. Patent Publication No.
2006/0212112, describes the use of liners and extenders to anchor
and seal such double-walled filling structures within the aorta.
The full disclosures of both these publications are incorporated
herein by reference. PCT Publication No. WO 01/21108 describes
expandable implants attached to a central graft for filling aortic
aneurysms. See also U.S. Pat. Nos. 5,330,528; 5,534,024; 5,843,160;
6,168,592; 6,190,402; 6,312,462; 6,312,463; U.S. Patent
Publications 2002/0045848; 2003/0014075; 2004/0204755;
2005/0004660; and PCT Publication No. WO 02/102282.
BRIEF SUMMARY OF THE INVENTION
[0013] In a first aspect of the present invention, a double-walled
filling structure comprises a thin, flexible, non-porous and
biocompatible outer material that prevents movement of fluids
across its boundary and that is flexible enough to fill and conform
to the irregular contours of the aneurysm wall. An inner lumen of
the filling structure may be made of the same or a different
material selected and oriented so as to have high resistance to
circumferential creep and elastic deflection. The inner lumen may
be reinforced by including a reinforcing member including fibers,
wires, strips, or a sleeve oriented circumferentially so as to
improve resistance to hoop stresses. The inner lumen may also be
reinforced by the use of multiple layers of material. The inner
lumen may be inserted into a tubular mesh or membrane of metal,
polymer, or fibers in order to provide resistance against creep. If
the inner lumen is tapered or contoured to provide a gradual change
in diameter from one end to the other, the reinforcing lumen may
also be tapered to match the lumen taper.
[0014] In a second aspect of the present invention, the inner lumen
of the filling structure is constructed of a material with
thickness and/or composition chosen to be capable of withstanding
the maximum pulsatile pressure exerted by blood flow, without
undergoing creep or significant elastic deformation. It is
generally desirable to minimize thickness of the filling structure,
so a variation on this aspect is to employ materials with
anisotropic stress properties oriented and processed so as to have
greatest strength in the circumferential direction. An example of
such a material is expanded polytetrafluoroethylene, or ePTFE,
which is typically stretched in one direction and may also be
calendared to reduce its thickness and decrease its porosity. The
ePTFE sheet exhibits anisotropic modulus with greatest value in the
pre-stress axis, and also exhibits a strain hardening property in
which the modulus increases with deformation along the axis of
pre-stress. Thus by constructing the inner lumen of ePTFE, with a
pre-stress axis oriented in the circumferential direction, it is
possible to resist creep caused by blood pressure. Other materials
may be employed in this capacity as well, provided they have
sufficient strength in at least one axis, and are biocompatible and
impervious to fluids.
[0015] A third aspect of the present invention involves attaching a
support structure to the inside of the inner lumen of the filling
structure. The internal support frame (endoframe) may be made of a
biocompatible superelastic material such as Nickel-Titanium alloy
(for example Nitinol), and may be used to support the inner lumen
of the filling structure while it is being filled with hardenable
material. The inner lumen of the filling structure may be contoured
so that it matches the diameter of the endoframe at every position
along its length to avoid wrinkles By attaching the lumen to the
frame at several points, the frame provides additional creep
resistance to the lumen. This may be involve suturing, heat
staking, solvent welding, or other methods well known in the art
for attaching dissimilar materials to each other. Alternatively,
the internal reinforcing elements may be made from
balloon-expandable materials like stainless steel, cobalt-chromium
alloys, etc. Ring shaped stiffeners may be sintered to either the
outside or the inside of the inner lumen of the filling structure
to provide support. In this case, the frame may comprise a set of
such rings. The rings may be made of a biocompatible metal or
polymer. The rings may be shaped such that they are compressible
and readily expandable in situ, for example by forming each ring
from an undulating or zigzag pattern.
[0016] In a fourth aspect of the present invention a reinforcing
tube surrounds an inner lumen of a filling structure to provide
additional reinforcement. This tube may be made of the same
material as the inner lumen, or it may differ. Because the
reinforcing tube does not contact blood or tissue, its
biocompatibility requirements are lessened. The reinforcing tube
may be of a continuous material, or it may be a mesh attached to
the inner lumen by one of several methods well known in the art,
including for example suturing, heat staking, solvent welding,
ultrasonic welding, or adhesives. The tube material is chosen to
have strength in the circumferential direction that, in combination
with the strength provided by the inner lumen, resists creep caused
by the peaks in blood pressure. Using Laplace's law:
hoop stress=pressure*vessel radius/wall thickness.
Using typical values for mean blood pressure=100 mmHg (healthy
80/120 mm Hg), radius R=7 mm (2-14 mm rounds to treat a 26 mm
aorta), and assuming wall thickness of 150 microns, the typical
stresses are about 600 MPa. Maximum stress is about 1100 MPa, and
minimum hoop stress is estimated to be about 300 MPa.
[0017] In another aspect of the present invention, the filling
medium may be modified through additives/covalent bonding so that
it adheres to the walls of the filling structure and keeps the
device intact and accommodates remodeling.
[0018] In still another aspect of the present invention, the inner
walls of the filling structure may be modified through additives,
coatings and covalent bonding so that the filling medium adheres to
the filling structure and maintains the shape of the device.
[0019] In yet another aspect of the present invention, the filling
structure includes two or more coaxial compartments, the inner of
which is a hollow cylinder surrounding the inner lumen, and the
outer of which is shaped to fill the aneurysm and conform to the
irregular contours of the aneurysm wall. The inner compartment may
be in fluid communication with the outer compartment. The inner and
outer compartments may have separate fill ports, or a valve or flap
may be provided to direct a flow of filling material first to one
region, and then to the other region. The filling material is
introduced to the inner region, and may flow to the outer region
when the inner region fills, thereby providing a continuous layer
of hardening medium surrounding the blood lumens of the filling
structure. This results in the inner region being completely filled
with a hollow cylinder of hardened filling medium reinforced by the
inner and middle layers of the filling structure itself, preventing
radial expansion. In addition, the inner compartment is sized such
that it may be fully expanded without wrinkles while the outer
compartment is sized to fill a wide range of aneurysm geometries
that may be encountered and therefore may be of an elastic
material, or of a flexible, substantially inelastic material such
as PTFE or ePTFE that is large enough to fill a range of aneurysm
cavities. In the latter case there may be wrinkles in the outer
section of the filling structure after filling depending on the
shape, size and pathophysiology of the aneurysm. These wrinkles may
interrupt the structure of the hardened filling medium so that it
may be broken into two or more sub-volumes, inhibiting its strength
and providing room to depressurize and allow for re-modeling as
part of the healing mechanism of the aneurysm.
[0020] The filling medium delivered to the inner region may be
selected to have material properties that enhance its resistance to
pulsatile pressure or creep. For example, the inner region material
may be a Polyethylene Glycol (PEG)-based Hydrogel with a higher
bulk modulus than the material delivered to the outer region. A
harder material in the inner compartment dampens pulsatile forces
and a softer material in the outer compartment allows ease of
shaping and remodeling.
[0021] Similarly, the material targeted to the outer region may for
example be selected to have lower viscosity before hardening so it
fills the sac more evenly, a different hardening time, or the
ability to bond with the wall of the filling structure. This may be
achieved for example through chemical/covalent bonding by adding
reactive functional groups to either the hydrogel or the inner wall
of the filling structure or both. Hydrogen bonding may be
preferentially used to create attachment of hydrogel to the inner
surface of the filling structure. This may entail imparting donor
hydrogen atoms and acceptor entity atoms in either the hydrogel or
the wall of the filling structure or both. Physical
adhesive/cohesive forces may be used to attach hydrogel to the
inner surface at various pre-determined locations on the interface.
The inner surface of the filling structure's outer wall may be
modified by surface derivitization or by lamination to allow the
filling material to bonds to it to improve overall strength.
[0022] In still another aspect of the invention, the filling
structure's outer surface is coated with substances that promote
the growth of epithelium on the outer surface, thus creating an
enclosure around the filling structure that serves to maintain
containment pressure over time. This approach may be combined with
other approaches described herein to add strength.
[0023] In another aspect of the present invention, a method for
treating an aneurysm comprises providing a double-walled filling
structure having an outer wall and an inner wall, and positioning
the double-walled filling structure adjacent the aneurysm. The
filling structure is filled with a hardenable fluid filling medium
so that the outer wall conforms to an inside surface of the
aneurysm and the inner wall forms a generally tubular lumen to
permit blood flow therethrough. The lumen is constrained from
creeping or elastically expanding due to the blood flow through the
lumen.
[0024] The constraining step may comprise providing a reinforcing
layer disposed at least partially around the tubular lumen, or
filling a compartment disposed at least partially around the
tubular lumen with the hardenable fluid filling medium.
[0025] These and other embodiments are described in further detail
in the following description related to the appended drawing
figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 illustrates the anatomy of an infrarenal abdominal
aortic aneurysm.
[0027] FIG. 2 illustrates a filling structure comprising a
multi-layer reinforced inner lumen.
[0028] FIG. 3 illustrates a filling structure comprising an inner
lumen with tapered ends.
[0029] FIG. 4 illustrates a filling structure comprising multiple
compartments.
[0030] FIGS. 5A-5D illustrate an exemplary method of deploying a
filling structure in an aneurysm.
DETAILED DESCRIPTION OF THE INVENTION
[0031] Referring to FIG. 1, the anatomy of an infrarenal abdominal
aortic aneurysm comprises the thoracic aorta (TA) having renal
arteries (RA) at its distal end above the iliac arteries (IA). The
abdominal aortic aneurysm (AAA) typically forms between the renal
arteries (RA) and the iliac arteries (IA) and may have regions of
mural thrombus (T) over portions of its inner surface (S).
[0032] FIG. 2 illustrates a filling structure 201 embodying aspects
of the invention. Filling structure 201 comprises central lumen 204
defined by luminal wall 202, outer wall 209, and reinforcing sleeve
203. Fill tube 208 is attached to a cannula during placement of the
device, and allows hardenable filling material to enter the
interior volume of the filling structure, then seals itself to
prevent backflow of filling material when the cannula is removed.
Fill tube 208 may comprise a tear line 210 created by a partial
perforation or notched edges. The tear line allows part or the
entire exterior portion of the fill tube to be removed when the
fill cannula is removed so that none of the fill tube protrudes
beyond the filling structure once the filling structure is placed.
This prevents contact between the fill tube and the artery wall,
reducing the risk of thrombosis.
[0033] Still referring to FIG. 2, reinforcing sleeve 203 may be
laminated, welded, sewn, or adhesively attached to central lumen
204, or may be a separate sleeve that is placed over central lumen
204 during the assembly process. Both reinforcing sleeve 203 and
central lumen 204 may vary in diameter in order to conform more
closely to the natural diameter of the target artery, particularly
at the ends. This may afford superior sealing by matching the
diameter of the filling structure more closely to the diameter of
the neck of the aneurysm.
[0034] As shown in FIG. 3, a filling structure 301 may be
constructed such that inner lumen 303 varies in diameter over the
length of the filling structure in order to increase filled volume
305 and improve sealing against one or more necks of the aneurysm.
In one aspect, the filling structure 301 has an exterior wall 302
and a lumen 303. The lumen 303 has a larger diameter 304 at each
end than at a point therebetween, and may comprise a cylindrical
middle portion 303a with one or more conical end portions 303b. The
slope of the shoulder of conical end portions 303b may be chosen to
control the shape of filling structure 301 after it is filled.
Choosing a maximum diameter of conical section 303b that is close
to the outside diameter of the filling structure results in a more
circular cross-section, while a smaller maximum diameter relative
to the outside diameter of filling structure 301 results in an oval
or eye-shaped cross-section. Other taper profiles for the inner
lumen may be selected; for example it is possible to use a
parabolic or hyperbolic profile to provide a continuous transition
from one inner diameter to another, which may reduce turbulent flow
in the lumen. Note that the foregoing description is for exemplary
purposes and is not meant to exclude other diameter profiles.
[0035] FIG. 4 illustrates a filling structure 401 comprising at
least two filling compartments. Endoframe 402 may be used to
support the filling structure while it is being filled, maintaining
a diameter of interior lumen 403 Inner compartment 404 may be
connected directly to a fill valve 407 such that filling material
enters compartment 404 forming an inner polymer jacket 405 before
flowing to outer compartment 406. In this aspect the two
compartments may be in fluid communication with each other,
optionally with a restriction between the two compartments such
that the viscosity of the filling medium inflates the inner
compartment fully before filling the outer compartment. U.S. patent
application Ser. No. 12/429,474 (Attorney Docket No.
025925-002610US) discloses various delivery system configurations
and methods for delivering and deploying a filling structure that
may be used for any of the filling structures disclosed herein, the
entire contents of which are incorporated herein by reference.
[0036] In an alternate aspect, inner compartment 404 may be
separated from outer compartment 406 and each compartment may have
a separate fill valve similar to fill valve 407. In this case valve
407 communicates with the inner compartment and another fill valve
(not shown) communicates with the outer compartment. This permits
the use of two different filling media, each with potentially
different material properties. For example, the inner
compartment-filling medium may be selected for a fast cure time to
allow rapid removal of the endoframe 402, or for a larger bulk
modulus to provide enhanced resistance to pulsatile pressure. The
outer compartment-filling medium may for example be selected for
enhanced adhesion to an inner wall of filling structure 401.
Separate fill valves also allow the compartments to be filled in a
controlled order. In one aspect, the inner compartment is filled
before the outer compartment to allow the inner compartment to be
fully filled, providing a solid structure for resisting pulsatile
pressure. The outer compartment is then filled sufficiently to fill
the aneurysm sac without overloading the artery wall.
[0037] Referring now to FIG. 5a, we describe an exemplary method of
placing and filling a multi-partition filling structure in an
aneurysm 500. Furled filling structure 501 is introduced to the
aneurysm on guidewire 503 and cannula 502. Sheath 504 is withdrawn
to release filling structure 501. Cannula 502 contains guidewire
503 as well as one or more optional lumens (not illustrated) for
filling the filling structure compartments, and possibly for
introducing an endoframe and expansion balloon, as well as lines
permitting detachment of the filling structure and other components
from the cannula for deployment.
[0038] Continuing to FIG. 5b, the unfurled filling structure may be
unfurled completely by filling with a solution containing contrast
agent, saline, combinations thereof, as well as other fluids. This
is advantageous since the walls of the filling structure may stick
against adjacent walls, especially after terminal sterilization and
storage. Once unfurled, the volume of solution required to unfurl
may be used as an estimate of the volume of hydrogel mix to
introduce in order to fill the aneurysm sac completely without
overpressure on the wall.
[0039] Continuing to FIG. 5c, endoframe 505 may be introduced into
the inner lumen of filling structure 501 to support the inner lumen
during the hydrogel filling step. Endoframe 505 may be
self-expanding, or may be expanded by an expandable member such as
a balloon (not illustrated) introduced via cannula 502. Endoframe
505 may be withdrawn after the filling step, or may be left in
place indefinitely.
[0040] Continuing to FIG. 5d, uncured liquid hydrogel is introduced
through cannula 502 into inner partition 506 of filling structure
501. In one aspect, inner partition 506 may be in restricted fluid
communication with outer partition 507 of filling structure 501. In
this case, once inner partition 506 is filled, hydrogel flows to
outer partition 507 via a passageway. The hydrogel's viscosity in
combination with the cross-section area of the passageway causes
inner partition 506 to stay inflated while outer partition 507
fills with the remaining volume of hydrogel until filling structure
501 completely fills the aneurysm sac. In another aspect, inner
partition 506 and outer partition 507 may be filled by independent
filling tubes (not illustrated) in cannula 502. In this aspect,
inner partition 506 is filled until a measured pressure of the
hydrogel reaches a threshold pressure, or until a dispensed volume
of hydrogel reaches a threshold volume indicating complete filling
of inner partition 506. Then outer partition 507 is filled with the
remaining volume of hydrogel as estimated in the pre-fill step
described previously. Note that the filling structure may comprise
more than two compartments, in which case the filling process
continues until all compartments are properly and completely
filled. Once the hydrogel cures--preferably in less than ten
minutes, and more preferably in less than five minutes, and even
more preferably in less than about 4 minutes, the filling tubes may
be detached from the filling structure and the cannula and
guidewire may be withdrawn. Note that this process may be conducted
on two filling structures simultaneously, with one filling
structure inserted through each iliac artery. Filling of the
filling structure may be performed with the endoframe expanded
fully or partially, or the endoframe may be unexpanded.
Additionally, the expandable member may be partially or fully
expanded, or unexpanded during the filling procedure. Filling may
also be visualized using fluoroscopy, ultrasound, or other methods
in order to ensure that the filling structure properly expands and
fills the aneurismal space.
[0041] While the above is a complete description of the preferred
embodiments of the invention, various alternatives, modifications,
and equivalents may be used. Therefore, the above description
should not be taken as limiting in scope of the invention which is
defined by the appended claims.
* * * * *