U.S. patent application number 10/201172 was filed with the patent office on 2004-01-22 for endoluminal expansion system.
Invention is credited to Armstrong, Joseph R., Cully, Edward H., Nordhausen, Craig T., Ulm, Mark J., Vonesh, Michael J..
Application Number | 20040015224 10/201172 |
Document ID | / |
Family ID | 30443596 |
Filed Date | 2004-01-22 |
United States Patent
Application |
20040015224 |
Kind Code |
A1 |
Armstrong, Joseph R. ; et
al. |
January 22, 2004 |
Endoluminal expansion system
Abstract
An endoprosthesis expansion system having, in combination, a
delivery component such as a length of catheter tubing having at
its distal end an intermediate sheath component, and an inner tube
within the full length of the delivery catheter and intermediate
sheath component. The inner tube has a protrusion affixed to its
distal end, and an expandable endoprosthesis is fitted in a
compacted state about the intermediate sheath, immediately proximal
to the protrusion. If the endoprosthesis is a self-expanding
endoprosthesis (as is preferred), an exterior constraining sheath
is required around the outer surface of the endoprosthesis.
Following insertion of the endoprosthesis and delivery system into
a body conduit (such as a blood vessel) and transport of the
endoprosthesis to the desired site within the body conduit, the
endoprosthesis is deployed by axially moving the protrusion against
the system, thereby applying a radially directed outward force and
causing simultaneous dilatation of the intermediate sheath and
disruption of the exterior constraining sheath. Disruption of the
exterior constraining sheath, in the case of a self-expanding
prosthesis, releases the stored energy in the formerly constrained
prosthesis, allowing it to expand and accomplish full deployment
against the luminal surface of the body conduit at the desired
site.
Inventors: |
Armstrong, Joseph R.;
(Flagstaff, AZ) ; Cully, Edward H.; (Flagstaff,
AZ) ; Nordhausen, Craig T.; (Flagstaff, AZ) ;
Ulm, Mark J.; (Flagstaff, AZ) ; Vonesh, Michael
J.; (Flagstaff, AZ) |
Correspondence
Address: |
W. L. Gore & Associates, Inc.
551 Paper Mill Road
P.O. Box 9206
Newark
DE
19714-9206
US
|
Family ID: |
30443596 |
Appl. No.: |
10/201172 |
Filed: |
July 22, 2002 |
Current U.S.
Class: |
623/1.12 |
Current CPC
Class: |
A61F 2/97 20130101; A61F
2002/9511 20130101; A61F 2/95 20130101; A61F 2/958 20130101 |
Class at
Publication: |
623/1.12 |
International
Class: |
A61F 002/06 |
Claims
We claim:
1. An endoluminal expansion system comprising: a) a protrusion
affixed to an elongate actuation member, said protrusion having a
maximum diameter of D.sub.2; b) a substantially tubular sheath
mounted coaxially about the elongate actuation member, said
elongate actuation member being axially movable with respect to the
substantially tubular sheath, said substantially tubular sheath
having an inside diameter of D.sub.1, wherein D.sub.2 is greater
than D.sub.1; and c) an expandable endoprosthesis affixed coaxially
about the substantially tubular sheath wherein one end of said
expandable endoprosthesis is adjacent to said protrusion.
2. An endoluminal expansion system according to claim 1 wherein
said endoprosthesis is a self-expanding endoprosthesis and is
contained within a disruptable constraining sheath.
3. An endoluminal expansion system according to claim 2 wherein
said constraining sheath is configured to be an implantable
constraining sheath.
4. An endoluminal expansion system according to claim 2 wherein
said constraining sheath is configured to be a removable
constraining sheath.
5. An endoluminal expansion system according to claim 2 wherein
said constraining sheath is disruptable via a row of
perforations.
6. An endoluminal expansion system according to claim 2 wherein
said constraining sheath comprises porous expanded
polytetrafluoroethylene.
7. An endoluminal expansion system according to claim 6 wherein
said constraining sheath comprises a delicate constraining sheath
contained within a packaging sheath that is removable prior to
insertion of the endoluminal expansion system into a body
conduit.
8. An endoluminal expansion system according to claim 1 wherein
said substantially tubular sheath includes at least one split along
its length.
9. An endoluminal expansion system according to claim 1 wherein
said substantially tubular sheath comprises a polymeric material
less than about 0.12 mm thick.
10. An endoluminal expansion system according to claim 1 wherein
said protrusion comprises a length of tubularly braided wire.
11. An endoluminal expansion system according to claim 1 wherein
said protrusion comprises an inflatable member.
12. An endoluminal expansion system according to claim 1 wherein
said elongate actuation member comprises a tube.
13. An endoluminal expansion system according to claim 1 wherein
said elongate actuation member comprises an elongate tensile
member
14. An endoluminal expansion system according to claim 13 wherein
said elongate tensile member comprises a guidewire.
15. An endoluminal expansion system according to claim 1 wherein
said system incorporates a tether element.
16. An endoluminal expansion system according to claim 1 wherein
said substantially tubular sheath includes an enlargement at its
distal end.
17. An endoluminal expansion system according to claim 16 wherein
said enlargement is a collar.
18. An endoluminal expansion system according to claim 1 wherein,
following the application of axial compression against an end of
the substantially tubular sheath by the protrusion, the
substantially tubular sheath assumes a corrugated shape.
19. An endoluminal expansion device comprising: a protrusion and an
associated actuation member, the protrusion having a maximum
diameter of D.sub.1; a substantially tubular sheath through which
the actuation member moves, the substantially tubular sheath having
a maximum diameter of D.sub.2, D.sub.2 being less than D.sub.1,
wherein when the protrusion is moved against the substantially
tubular sheath, the substantially tubular sheath is dilated to
cause an expansion force.
20. An endoluminal expansion device according to claim 19 wherein
the substantially tubular sheath includes at least one split along
at least a portion of its length.
21. An expandable endoprosthesis and delivery device comprising the
endoprosthesis mounted on a substantially tubular sheath; wherein
the delivery device comprises a protrusion and an associated
actuation member, the protrusion being proportioned to enlarge the
endoprosthesis when the protrusion is actuated against the
substantially tubular sheath and endoprosthesis.
22. An endoluminal expansion system according to claim 21 wherein
said endoprosthesis is a self-expanding endoprosthesis and is
contained within a disruptable constraining sheath.
23. An endoluminal expansion system according to claim 22 wherein
said constraining sheath is disruptable via a row of
perforations.
24. An endoluminal expansion system according to claim 23 wherein
said constraining sheath comprises porous expanded
polytetrafluoroethylene.
25. An endoluminal expansion system according to claim 24 wherein
said constraining sheath comprises a delicate constraining sheath
contained within a packaging sheath that is removable prior to
insertion of the endoluminal expansion system into a body
conduit.
26. An endoluminal expansion system according to claim 21 wherein
said substantially tubular sheath includes at least one split along
its length.
27. An endoluminal expansion system according to claim 21 wherein
said substantially tubular sheath comprises a polymeric material
less than about 0.12 mm thick.
28. A method of expanding an expandable endoluminal prosthesis
wherein said endoprosthesis is part of a delivery system
comprising: a) a protrusion affixed to an elongate actuation
member, said protrusion having a maximum diameter of D.sub.2; b) a
substantially tubular sheath mounted coaxially about the elongate
actuation member, said elongate actuation member being axially
movable with respect to the substantially tubular sheath, said
substantially tubular sheath having an inside diameter of D.sub.1,
wherein D.sub.2 is greater than D.sub.1; and c) an expandable
endoprosthesis affixed coaxially about the substantially tubular
sheath wherein one end of said expandable endoprosthesis is
adjacent said protrusion; said method comprising moving said
elongate actuation member and protrusion against said substantially
tubular sheath and expandable endoprosthesis, thereby applying a
radially outwardly directed force to the endoprosthesis and thereby
initiating expansion of the endoprosthesis.
29. A method according to claim 28 wherein said substantially
tubular sheath includes at least one split along its length.
30. A method according to claim 28 wherein said expandable
endoprosthesis is a self-expanding endoprosthesis contained within
a disruptable constraining sheath.
31. A method according to claim 30 wherein said constraining sheath
is configured as an implantable constraining sheath.
32. A method according to claim 30 wherein said constraining sheath
is configured as a removable constraining sheath.
33. A method according to claim 30 wherein said constraining sheath
comprises porous expanded polytetrafluoroethylene.
34. A method according to claim 30 wherein said constraining sheath
is disruptable via a row of perforations extending along a length
of the constraining sheath.
35. A method according to claim 34 wherein said constraining sheath
comprises porous expanded polytetrafluoroethylene.
36. A method according to claim 30 wherein said constraining sheath
comprises a delicate constraining sheath contained within a
packaging sheath that is removable prior to insertion of said
endoprosthesis into a body conduit.
37. An endoluminal expansion system comprising: a) an elongate
actuation member having a distal end; b) a substantially tubular
sheath mounted coaxially about the elongate actuation member, said
elongate actuation member being axially movable with respect to the
substantially tubular sheath, wherein the substantially tubular
sheath has a distal end that is secured to the distal end of the
elongate actuation member; and c) an expandable endoprosthesis
affixed coaxially about the substantially tubular sheath; wherein
the application of tension to the elongate actuation member applies
compression to the substantially tubular sheath whereby a radially
outward force is applied to the expandable endoprosthesis by the
substantially tubular sheath.
38. An endoluminal expansion system according to claim 37 wherein
said endoprosthesis is a self-expanding endoprosthesis and is
contained within a disruptable constraining sheath.
39. An endoluminal expansion system according to claim 38 wherein
said constraining sheath is disruptable via a row of
perforations.
40. An endoluminal expansion system according to claim 38 wherein
said constraining sheath comprises porous expanded
polytetrafluoroethylene.
41. An endoluminal expansion system according to claim 38 wherein
said constraining sheath comprises a delicate constraining sheath
contained within a packaging sheath that is removable prior to
insertion of the endoluminal expansion system into a body
conduit.
42. An endoluminal expansion system according to claim 37 wherein
said elongate actuation member comprises a tube.
43. An endoluminal expansion system according to claim 37 wherein
said elongate actuation member comprises an elongate tensile
member
44. An endoluminal expansion system according to claim 43 wherein
said elongate tensile member comprises a guidewire.
45. An endoluminal expansion system according to claim 37 wherein
said system incorporates a tether element.
46. An endoluminal expansion system according to claim 37 wherein
said substantially tubular sheath includes an enlargement at its
distal end.
47. An endoluminal expansion system according to claim 46 wherein
said enlargement is a collar.
48. An endoluminal expansion system according to claim 37 wherein
the application of compression to the substantially tubular sheath
causes the substantially tubular sheath to assume a corrugated
shape.
49. An endoluminal expansion system comprising an endoprosthesis
and a delivery catheter having a balloon affixed at a distal end
thereof, said system including a tether secured to the delivery
catheter, wherein said tether includes a length that is captive
between the balloon and the endoprosthesis.
50. An endoluminal expansion system according to claim 49 wherein
inflation of the balloon results in expansion and deployment of the
endoprosthesis and wherein said length of tether is not captive
following inflation and subsequent deflation of the balloon.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the transcatheter delivery
and remote deployment of implantable medical devices and more
particularly to a system for the expansion and deployment of
endoprostheses.
BACKGROUND OF THE INVENTION
[0002] Endoluminal therapies typically involve the insertion of a
delivery catheter that transports an implantable prosthetic device
into a body conduit through a small, often percutaneous, remote
access site. Once access to the body conduit is achieved, the
delivery catheter is used to mediate intraluminal delivery and
subsequent deployment of the prosthesis via one of several
techniques. In this fashion, the prosthesis can be remotely
implanted to achieve a therapeutic outcome. In contrast to
conventional surgical therapies, endoluminal treatments are
distinguished by their "minimally invasive" nature.
[0003] Self-expanding endoprostheses are generally comprised of a
stent component with or without a graft covering over the stent
interstices. They are designed to spontaneous dilate (i.e.,
elastically recover) from their delivery diameter, through a range
of intermediary diameters, up to a maximal, pre-determined
functional diameter. The endoluminal delivery and deployment of
self-expanding endoprostheses pose several unique problems. First,
the endoprosthesis itself must be radially compacted to a suitable
introductory size (or delivery diameter) to allow insertion into
the vasculature, then it must be constrained in that compacted
state and mounted onto a delivery device such as a catheter shaft.
Subsequently, the constraint must be removed in order to allow the
endoprosthesis to expand to its functional diameter and achieve the
desired therapeutic outcome. Preferably, the means of constraint
will not adversely affect the delivery catheter performance (e.g.,
detracting from the flexibility of the delivery system) or add
significantly to introductory profile. The constraint must also
incorporate some type of release mechanism or scheme that can be
remotely actuated by the implanting clinician. Consequently,
deployment methodologies that are consistent with conventional
interventional practices are preferred.
[0004] Delivery mechanisms for self-expanding endoprostheses of the
prior art may be generally classified into one of two general
categories, either coaxial sheaths or fiber-based constraints.
Delivery systems also exist that use both of these types of
mechanisms in combination.
[0005] Tubular coaxial sheaths are one approach used to constrain
the compacted self-expanding endoprosthesis. Normally, these
coaxial sheaths extend over the entire length of an inner delivery
catheter onto which the endoprosthesis is mounted near the catheter
tip (i.e., leading end). Deployment is typically initiated by
pulling on a handle or knob located near the hub (i.e., trailing
end) of the catheter, which retracts the constraining sheath and
allows the device to expand. During this procedure, the clinician
maintains the position of the device by holding the inner
(delivery) catheter in a stationary position. Existing problems
and/or complications with the tubular coaxial sheath type of
delivery system include friction between compacted device and
constraining sheath, friction between the constraining sheath and
delivery catheter, and friction between the delivery catheter and
constraining sheath hemostasis valve, all of which can hinder
deployment accuracy, speed and control. Additionally, a tubular
coaxial constraining sheath can also reduce flexibility and add
introductory profile due to the thickness of the constraining
sheath.
[0006] In the fiber-based delivery systems, the self-expanding
endoprosthesis is constrained in the delivery profile by one or
more removable fibrous strands, with or without an additional
implantable constraint element. The endoprosthesis is released from
its compacted-state through tension applied to a deployment "cord"
that normally runs through an additional lumen within the delivery
catheter. Typically, applying tension to the deployment cord
initiates the release of the fiber constraint by, for example,
unlacing linear slip knots (see Lau, et al., U.S. Pat. No.
5,919,225), removing circumferential croquet knots (e.g., Strecker,
U.S. Pat. No. 5,405,378), or detaching the interlocking loops of a
warp-knitted constraint (e.g., Armstrong et al., U.S. Pat. No.
6,224,627). Other fiber-based delivery systems are described by
Lindemann, U.S. Pat. No. 4,878,906, and Hillstead, U.S. Pat. No.
5,019,085.
[0007] Another variant of the fiber-based delivery systems is the
mechanism employed in the EXCLUDER.RTM. endoprosthesis marketed by
W. L. Gore and Associates, Inc (Flagstaff, Ariz.). This mechanism
entails a "chain-stitch" sewn into the seam of a biocompatible
constraining tube that contains the compacted endoprosthesis.
Applying tension to the fibrous constraint in this mechanism allows
the seam in the biocompatible constraining tube to be open, and the
self-expanding endoprosthesis to deploy. The biocompatible
constraining tube is implanted along with the endoprosthesis,
trapped between the abluminal surface of the device and the wall of
the host vessel. See WO98/27894.
[0008] Problems with fiber-based type of delivery systems include
possible premature deployment during introduction to the vascular
system through hemostasis valves, extra lumens required on the
delivery catheter which can increase profile, possible snagging of
fiber(s) on the compacted implantable device, the possibility of
emboli resulting from moving lines between the catheter and the
blood vessel, and possible breakage of the deployment cord
itself.
[0009] U.S. Pat. Nos. 5,755,769 and 6,019,787 to Richard et al.
teach another constraining sheath around a self-expanding stent.
The sheath is cut longitudinally into several segments by cutting
wires or fibers actuated by pulling a handle at the opposite end of
the delivery system. The sheath is attached to or integral to the
delivery catheter with the result that the segments are removed
with the catheter following stent deployment. No catheter balloon
or other means for exerting a circumferential disrupting force to
the sheath is suggested, nor are materials appropriate for the
sheath suggested. This design requires lines to run over the length
of the catheter.
[0010] U.S. Pat. No. 6,086,610 to Duerig et al. teaches a
self-expanding stent provided with a tubular constraining sheath
that is plastically deformable by a circumferential distending
force such as a catheter balloon. This sheath remains implanted
with the stent following deployment and fully covers the entire
circumference of the stent in the fashion of a conventional stent
covering, i.e., the tubular sheath is not disrupted. The Duerig et
al. device is delivered from a conventional balloon catheter, but
thought to have limitations, including radial recoil of the sheath
after the balloon is pressurized and deflated, which can compromise
luminal gain. Further, the presence of the cover may adversely
affect the ability of the stent to fully deploy, and the balloon
length must be equal to or longer than the stent, and this long
balloon can potentially damage the vessel.
SUMMARY OF THE INVENTION
[0011] The present invention relates to an endoprosthesis expansion
system comprising, in combination, a delivery component such as a
length of catheter tubing having at its distal end an intermediate
sheath component, and an inner elongate actuation member that is
preferably an inner tube located within the full length of the
delivery catheter and intermediate sheath component. The inner
elongate actuation member (e.g., inner tube) has a protrusion
affixed to its distal end, and an expandable endoprosthesis is
fitted in a compacted state about the intermediate sheath, proximal
to the protrusion. If the endoprosthesis is a self-expanding
endoprosthesis (as is preferred), an exterior constraining sheath
is required around the outer surface of the endoprosthesis to
contain the endoprosthesis in a compacted configuration. Following
insertion of the endoprosthesis and delivery system into a body
conduit (such as a blood vessel) and transport of the
endoprosthesis to the desired site within the body conduit, the
endoprosthesis is deployed by axially moving the protrusion through
the system, thereby applying a radially directed outward force and
causing simultaneous dilatation of the intermediate sheath and
disruption of the exterior constraining sheath. Alternatively,
axial movement of the elongate actuation member against the end of
the intermediate sheath, applying axial compression to the
intermediate sheath, may cause the intermediate sheath to shorten
and simultaneously increase in diameter, thereby initiating
expansion and deployment of the endoprosthesis. Disruption of the
exterior constraining sheath, in the case of a self-expanding
prosthesis, releases the stored energy in the formerly constrained
prosthesis, allowing it to spontaneously expand and accomplish full
deployment against the luminal surface of the body conduit at the
desired site.
[0012] The exterior constraining sheath is preferably made of an
implantable material and may be left captured between the
endoprosthesis and the luminal surface of the body conduit.
Alternatively, the exterior constraining sheath may be secured to
the adjacent delivery catheter and withdrawn from between the
endoprosthesis and the wall of the body conduit when the delivery
catheter is withdrawn.
[0013] If a non-self-expanding endoprosthesis is used (e.g., a
balloon-expandable stent), diametrical expansion may be
accomplished by moving the protrusion axially through the stent,
thereby enlarging the diameter by plastically deforming the stent.
Likewise, as described with the self-expanding stent embodiment,
the application of axial compression against one end of the
intermediate sheath by the protrusion can cause an increase in the
diameter of the intermediate sheath, forcing a corresponding
diametrical increase in the balloon expandable stent.
[0014] In addition to stent devices, the endoprostheses utilized
with the present invention may also be stent-grafts. The phrase
"stent-graft" is used herein to describe a stent provided with a
covering, typically of a vascular graft material such as porous
expanded polytetrafluoroethylene (ePTFE) or polyethylene
terephthalate (PET). The covering may be provided over either or
both of the inner and outer surfaces of the stent. The covering may
cover a portion of the otherwise open stent interstices or it may
cover all of the stent interstices.
[0015] While the system of the present invention is intended
primarily for stents and stent-grafts for use in vascular repairs,
it is also useful for expandable devices for other applications in
other body conduits, e.g., esophageal or biliary duct repairs.
[0016] While a protrusion can be used to initiate deployment
without an intermediate sheath inside the endoprosthesis, the use
of the intermediate sheath, made from a thin, strong and lubricious
material, prevents the protrusion from damaging the endoprosthesis
(particularly if the endoprosthesis is a stent-graft with a
covering on the luminal surface). It also reduces the likelihood of
"bunching" of the endoprosthesis due to the application of an axial
force. It can likewise reduce the amount of axial force required as
well as reducing the variability of the axial force (as the
protrusion moves along the internal length of the endoprosthesis),
by providing a uniform compression resistance against the
protrusion as opposed to the variable resistance provided by the
wire surface of the interior of an endoprosthesis.
[0017] Both the exterior constraining sheath and the intermediate
sheath may be made to be dilatable or disruptable by various and
similar means. For the exterior constraining sheath, it is
preferred to provide a line of perforations partially or entirely
through the wall of the tubular constraining sheath, parallel to
the longitudinal axis of the tubular constraining sheath. The
constraining sheath may be caused to disrupt by splitting along
this line of perforations, upon the application of an outwardly
directed radial force from within the sheath (and within the
contained endoprosthesis).
[0018] For the intermediate sheath located within the
endoprosthesis, it is preferred that it is of a substantially
tubular form and is dilatable via one or more, equally
radially-spaced apart splits are used along the length of that
sheath. Alternatively, the intermediate sheath may be elastically
or plastically deformable by the protrusion. In other alternatives,
the intermediate sheath may be caused to be split, ripped, torn or
otherwise changed in proportion by the movement of the protrusion
against and/or through the intermediate sheath. Any of these
mechanisms are considered to constitute dilatation of the
intermediate sheath. It is apparent that the tubular form of the
intermediate sheath includes various embodiments and as such is
considered to be a substantially tubular sheath.
[0019] The present invention also provides a means of controlling
the radial dynamics of device deployment. For example, the present
invention can be configured to `pop` open to allow rapid device
deployment, or alternatively to undergo more gradual, controlled,
stepwise release during device deployment, or a combination of
both.
[0020] The constraining sheath may be imbibed with various
pharmaceutical, biological, or genetic therapies for targeted
luminal delivery of these substances. Following deployment of the
endoprosthesis, these therapeutic agents can be released over time.
An advantage of this approach is that the loading of the sheath
with any of these therapeutic agents can be performed independent
of the endoprosthesis manufacture. Further, radiopaque elements may
be incorporated into the constraining sheath (or other system
components, notably the catheter tubes) to facilitate fluoroscopic
visualization.
[0021] The present invention may also be used to deliver and deploy
multiple devices positioned in sequential order on the delivery
catheter.
[0022] In a preferred embodiment, the constraining sheath can be
made to be extremely thin, or "delicate," for minimal implantation
profile. Such a delicate constraining sheath is not adequate,
without further exterior support, to constrain the endoprosthesis
assembly (particularly when the assembly includes a self-expanding
endoprosthesis) for very long periods of time or for shorter
periods when exposed to elevated temperatures. The use of such a
delicate constraining sheath is made practically possible when the
assembly is provided with an additional tubular packaging sheath
that prevents inadvertent disruption of the constraining sheath or
undesirable increase in diameter of the assembly (e.g., in an
amount of 0.15 mm or more). The tubular packaging sheath, fitted
coaxially about the exterior of the "delicate" constraining sheath,
is removed prior to implantation and accordingly is not required to
be made of an implantable material or a material with a thin wall.
Alternatively, the endoprosthesis assembly may incorporate such a
delicate constraining sheath without the use of a packaging sheath
if it is stored at reduced temperatures, such as 5.degree. C. or
less, prior to implantation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a longitudinal cross section of a compacted and
constrained endoprosthesis mounted on an intermediate sheath, which
is mounted upon an inner tube incorporating a protrusion at the
distal end that, when moved axially through or against the
intermediate sheath and endoprosthesis, applies a force directed
radially outward to initiate deployment of the endoprosthesis.
[0024] FIG. 2A is a transverse cross sectional view taken at
section A-A of FIG. 1.
[0025] FIG. 2B is a transverse cross sectional view taken at
section A-A of FIG. 1 wherein, in an alternative embodiment, the
intermediate sheath is split in one place, allowing it to enlarge
diametrically when the protrusion of FIG. 1 is passed through it or
applies compression against the end of the intermediate sheath.
[0026] FIG. 2C is a transverse cross sectional view taken at
section A-A of FIG. 1 wherein, in another alternative, the
intermediate sheath is split and coiled upon itself (in jelly-roll
fashion).
[0027] FIG. 2D is a transverse cross sectional view taken at
section A-A of FIG. 1 wherein, in another alternative, the
intermediate sheath is split in several places.
[0028] FIG. 2E is a transverse cross section of a preferred
constraining sheath construction.
[0029] FIG. 3 is a longitudinal cross section of a compacted and
constrained endoprosthesis describing a preferred embodiment of the
system of the present invention.
[0030] FIG. 4A is a longitudinal cross section of the
endoprosthesis being deployed within a body conduit.
[0031] FIG. 4B is an end view of endoprosthesis deployment depicted
in FIG. 4A.
[0032] FIGS. 5A and 5C-5H are longitudinal cross-sections of the
inner tube and protrusion, describing various embodiments of the
protrusion.
[0033] FIG. 5B is a transverse cross-sectional view taken at
section B-B of FIG. 5A of the protrusion of FIG. 1, describing an
embodiment wherein the transverse cross-section of the protrusion
is not round.
[0034] FIG. 6A is a longitudinal cross-section of the protrusion of
FIG. 1, wherein the protrusion is attached to a guide wire.
[0035] FIG. 6B is a longitudinal cross-section of the protrusion of
FIG. 1, wherein the protrusion is integral to a guide wire.
[0036] FIG. 6C is a longitudinal cross-section of the protrusion of
FIG. 1, wherein the protrusion is attached to an elongate tensile
member, such as a fiber, strand or wire.
[0037] FIG. 7A is a longitudinal cross section of a compacted and
constrained endoprosthesis incorporating a tether element with an
enlargement at the distal end of the tether element, intended to
prevent unintentional axial movement of the endoprosthesis.
[0038] FIG. 7B is a transverse cross-section taken at section C-C
of FIG. 7 describing the tether element.
[0039] FIGS. 8A-8C are longitudinal cross sections describing
alternative embodiments of the tether element.
[0040] FIG. 9 is a longitudinal cross section of a compacted and
constrained endoprosthesis incorporating a distensible collar
positioned at the end of the endoprosthesis and intended to prevent
unintentional axial movement of the endoprosthesis
[0041] FIG. 10 is a transverse cross sectional view taken at
section D-D of FIG. 9, describing the distensible collar
element.
[0042] FIGS. 11A-11C, 12A and 12B are perspective views describing
alternative embodiments of the present invention, primarily with
regard to variations of the substantially tubular, intermediate
sheath.
DETAILED DESCRIPTION OF THE INVENTION
[0043] FIG. 1 is a longitudinal cross section of the endoprosthesis
expansion system 10 of the present invention. The system 10 has a
proximal end 10a and a distal end 10b, wherein proximal end 10a is
considered to be the end from which a delivery catheter extends to
a site at which the system was originally inserted into a body
conduit. Endoprosthesis 11 is indicative of any type of endoluminal
medical device which might be usefully contained at a smaller
diameter for insertion into a body conduit and subsequently
deployed to a larger diameter at a desired location within the body
conduit. The endoprosthesis is preferably a self-expanding device,
and is most preferably a stent of the self-expanding type. While
these stents are most commonly used for repair of the vasculature
(e.g., repair of stenoses or aneurysmal repair), they are also used
for other applications in other body conduits (e.g., esophageal or
bile duct repairs). These self-expanding stents are typically of
nitinol wire although other materials may be used, e.g., stainless
steels or polymeric materials including resorbable polymers.
[0044] Alternatively, some balloon expandable devices may be
expanded with the present inventive system, without requiring an
exterior constraining sheath as do self-expanding devices.
[0045] According to the present invention, a self expanding device
in use as a part of the present endoprosthesis expansion system is
provided with an exterior constraining sheath to retain the
self-expanding endoprosthesis at its small, compacted diameter at
which it is intended to be inserted into a body conduit for
subsequent expansion and deployment. The constraining sheath is
disrupted by activation of the expansion and deployment mechanism
of the present invention. The constraining sheath is preferably
made from an implantable material, most preferably a tube of porous
expanded PTFE (hereinafter ePTFE), made generally as taught by U.S.
Pat. Nos. 3,953,566 and 4,187,390 to Gore. The tube is most
preferably provided with a line of perforations through the wall,
parallel to the length of the tube. The line of perforations
provides a yield point along which the constraining sheath will
disrupt by splitting. Forcibly expanding the endoprosthesis in a
radially outward direction, using force applied from within the
lumen of the endoprosthesis, causes the perforation line to
disrupt, initiating expansion and deployment of the self-expanding
endoprosthesis. The disrupted, now-split constraining sheath, being
of an implantable material such as ePTFE, preferably remains
implanted with the deployed endoprosthesis, held captive between
the endoprosthesis and the wall of the body conduit at the site of
deployment. As such, the implantable constraining sheath may
optionally be attached to the exterior surface of the
self-expanding stent, preferably along an axially-oriented line
that is 180.degree. opposite the line of perforations.
Alternatively, the constraining sheath can be configured to be
removable following deployment of the endoprosthesis, by having
previously secured it to a component of the delivery system such as
a catheter shaft and withdrawing it from between the endoprosthesis
and the wall of the body conduit when the catheter is
withdrawn.
[0046] The endoprosthesis may be a stent-graft having a stent
component and a covering over some or all of the open interstices
of the stent. The covering may be provided over either or both of
the inner and outer surfaces of the stent. It is preferably ePTFE,
and can be attached to the stent by any of various means known in
the art. Any such stent covering is in addition to and preferably
separate from the constraining sheath used with a self-expanding
endoprosthesis.
[0047] FIG. 1 shows a compacted and constrained endoprosthesis 11
mounted on an intermediate sheath 20, which is in turn mounted upon
inner tube 30. As a self-expanding endoprosthesis is described by
the figures, it is shown with a constraining sheath 13 about its
exterior surface. Constraining sheath 13, as will be described, is
disruptable to allow for expansion and deployment of endoprosthesis
11 at a desired site within a body conduit.
[0048] Inner tube 30 possesses at its distal end a protrusion 31
having a maximum diameter 32 (taken perpendicular to the
longitudinal axis 12 of the system 10) that is larger than the
inner diameter 22 of intermediate sheath 20 (also taken
perpendicular to longitudinal axis 12). Intermediate sheath 20 is
preferably an extension of a delivery catheter extending beyond the
insertion site at which endoprosthesis and associated delivery
system entered the body conduit. Intermediate sheath 20 is
preferably made from a thin, strong and lubricious polymeric
material such as PET. Intermediate sheath 20 is preferably as thin
or thinner than about 0.12 mm. In one alternative, the intermediate
sheath may be an integral part of the delivery catheter tube.
[0049] Most preferably, inner tube 30 comprises a composite tube
having an inner PTFE lining 24 of about 0.03 mm thickness, and an
outer jacket 25 of polyamide, about 0.18 mm thick, having a braided
stainless steel wire reinforcement (24 picks/cm, rectangular cross
section wire 0.01.times.0.07 mm, Fluorotek, Easton Pa.) embedded in
the wall of the jacket 25.
[0050] Protrusion 31 is preferably a separate component, also of
polyamide, that is melt-bonded to the exterior surface of the inner
tube at a desired location at one end of a length of the inner
tube. Melt bonding is accomplished by placing a mandrel inside
inner tube 30, fitting the protrusion 31 over the inner tube 30,
fitting a short length of fluorinated ethylene propylene shrink
tubing over the protrusion 31, and heating the assembly above the
melt temperature of polyamide thereby causing simultaneous
shrinking of the shrink-tubing. After heating, the shrink tubing is
carefully removed with the aid of a scalpel blade, taking care not
to damage the exterior surface of the protrusion 31 or the
polyamide tubing 30. Finally, the mandrel is removed from within
the tube. Multiple melt steps may be required to adequately
increase the protrusion diameter to the extent desired.
[0051] FIG. 2A is a transverse cross sectional view taken at
section A-A of FIG. 1 wherein the intermediate sheath 20 is
diametrically distensible when compressed axially and distended
diametrically when protrusion 31 is moved axially against one end
of the intermediate sheath or through its lumen. Endoprosthesis 11,
in this instance a self-expanding endoprosthesis, is shown enclosed
by constraining sheath 13. Constraining sheath 13 is provided with
a line of perforations 14 that extends for the length of the
constraining sheath 13, enabling it to subsequently disrupt along
this split line 14 when the endoprosthesis is deployed.
[0052] While it is possible to initiate expansion and deployment of
a constrained, self-expanding endoprosthesis without the use of
intermediate sheath 20, the use of this additional component has
been found to aid in the practical expansion of an endoprosthesis
via axial movement of a protrusion 31 against the end of the
intermediate sheath 20 or through the center of the intermediate
sheath 20 and endoprosthesis 11. Without the intermediate sheath
20, the direct contact of the protrusion 31 against the inner
surface of the endoprosthesis 11 may result in bunching up of the
prosthesis axially and possible damage to the endoprosthesis,
particularly if it is a stent-graft with a covering on the luminal
surface of the stent that is vulnerable to damage from the
protrusion 31. The use of intermediate sheath 20 provides for more
uniform axial compression resistance against the force exerted by
the protrusion 31, thereby improving uniformity of the expansion
and deployment of the endoprosthesis. Likewise, the use of a
lubricious material such as PET for the intermediate sheath 20 aids
in reducing and improving the uniformity of the axial effort that
must be applied via a guidewire and/or catheter shaft to cause
expansion and deployment of endoprosthesis 11.
[0053] FIG. 2B is a transverse cross sectional view taken at
section A-A of FIG. 1 showing an alternative embodiment of
intermediate sheath 20 wherein the intermediate sheath 20 is
provided with a longitudinally-oriented split 21 in one place, in a
direction parallel to longitudinal axis 12, allowing it to enlarge
when the protrusion 31 applies axial compression against one end or
is passed through it. While the intermediate sheath 20 is most
preferably split entirely through its thickness, it may also be
split through only a portion of the thickness if the remaining
unsplit thickness will yield reliably when the protrusion 31 is
forcibly pulled through the center of the intermediate sheath
20.
[0054] FIG. 2C is a transverse cross sectional view taken at the
same location with respect to FIG. 1, showing another alternative
embodiment of sheath 20 wherein sheath 20 is coiled upon itself (in
jelly-roll fashion), thereby allowing it to enlarge when the
protrusion 31 is passed through it or applies axial compression
against one end.
[0055] FIG. 2D is a transverse cross sectional view taken at
section A-A of FIG. 1 wherein the intermediate sheath 20 is
provided with multiple splits 21 in several places, thereby
enabling it to expand when the protrusion of FIG. 1 is passed
through it or applies axial compression against one end.
[0056] FIG. 2E is a transverse cross section describing a preferred
construction of a constraining sheath 13 for use around the
exterior surfaces of a self-expanding endoprosthesis 11.
Constraining sheath 13 comprises a wrap of a thin ePTFE film 26,
made as taught by U.S. Pat. No. 5,814,405 to Branca et al. The
particular ePTFE film used has a bulk density of about 0.25 g/cc
and is provided with a discontinuous, porous coating of fluorinated
ethylene propylene. It has a thickness of about 0.02 mm and a width
that is greater than the length of the endoprosthesis 11 intended
to be constrained. Four layers of this film 26 are sequentially
wrapped about the surface of a stainless steel mandrel having a
diameter equal to the outside diameter of the compacted
endoprosthesis 11 intended to be constrained, with the
circumferential wrapping of the mandrel accomplished in the machine
direction of the film. A line of perforations 14 are provided for
the full length of the tube through the thickness of this film 26
using a laser, after which the helical wrapping is completed with a
fifth layer of the film. The resulting five layer tube, still on
the mandrel, is restrained against the surface of the mandrel at
the tube ends and placed into an oven set at a temperature of about
320.degree. C. for about five minutes, after which it is removed
from the oven and allowed to cool. The end restraints are removed
and the five layer tube is then removed from the mandrel and
trimmed to the desired length equivalent to the length of the
endoprosthesis 11. The resulting constraining sheath 13 is ready to
be fitted about the exterior surface of compacted endoprosthesis
11. The endoprosthesis may be compacted by drawing it through a
funnel with the aid of a fiber temporarily attached to the
endoprosthesis. The endprosthesis is drawn through the funnel into
a length of metal or plastic tubing of constant diameter and
finally into the constraining sheath.
[0057] FIG. 3 is a longitudinal cross section of a preferred
embodiment wherein a separate intermediate sheath 20 is affixed to
the distal end of a delivery catheter tube 23. The delivery
catheter tube 23 preferably is a length of the composite tubing
described above having the PTFE lining within a wire-reinforced
polyamide jacket. The inside diameter of this tubing is such that
it provides a slight clearance for the outside diameter of the
inner tube 30. The PTFE liner of both tubes allows for smooth axial
operation of other components (tubes or wires) within the lumen of
either tube.
[0058] Intermediate sheath 20 comprises a length of heat shrinkable
PET tubing of about 0.03 mm thickness (Advanced Polymers Inc.,
Salem N.H.), fitted over the distal end of the delivery catheter
tube 23, and joined to that tube with cyanoacrylate adhesive. After
the adhesive has set, tension and heat are applied to the length of
thin PET tubing to cause it to shrink in diameter in an amount to
allow it to fit snugly over the outer surface of the inner tube 30.
An approximately 5 mm long length of the PET tubing is left
unshrunk to accommodate at least a portion of the protrusion 31
when it is subsequently drawn through the endoprosthesis 11. The
length of the intermediate sheath 20 is cut off transversely to a
length that allows it to extend beyond the distal end of
endoprosthesis 11. Preferably, the full length of inner sheath 20
extending beyond the end delivery catheter tube 23 is slit in a
direction parallel to longitudinal axis 12, forming intermediate
sheath split 21 (FIG. 2B). Compacted endoprosthesis 11 is fitted
around the slit intermediate sheath 20, and protrusion 31 is then
fitted about the distal end of inner tube 30 as previously
described.
[0059] FIG. 4A is a longitudinal cross section of the
endoprosthesis 11 being deployed within a body conduit 50; FIG. 4B
is an end view looking in a proximal direction of this deployment.
Protrusion 31 is moved axially through intermediate sheath 20 and
prosthesis 11 via tension applied to intermediate sheath 20.
Intermediate sheath 20 is preferably the distal end of a tubular
catheter shaft which supplies resistance compressively to the inner
tube 30 and protrusion 31 (affixed to the inner tube 30) when those
components are pulled axially through the endoprosthesis in a
proximal direction. The mechanical advantage offered by inclined
plane 33 on the leading edge or proximal side of protrusion 31, is
utilized to apply a radial force to intermediate sheath 20, thereby
causing disruption of the intermediate sheath 20. This radial force
is at first resisted compressively by intermediate sheath 20, and
quickly results in disruption of intermediate sheath 20, thereby
initiating deployment of the self-expanding endoprosthesis 11. The
expansion of endoprosthesis 11 progresses axially toward the
proximal end 10a of the system 10.
[0060] The embodiment described in FIGS. 4A and 4B is that of FIG.
2D, wherein intermediate sheath is provided with multiple splits 21
along its length, in this instance 4 parallel and equally spaced
splits. The end view of FIG. 4B shows the separation of these
splits as the deployment progresses toward the proximal end of the
system.
[0061] FIGS. 5A and 5C-5H are longitudinal cross sectional views of
the inner tube 30 showing various embodiments of protrusion 31.
These show that protrusion 31 may take any of various forms and are
intended as exemplary and are not therefore limiting. The
fundamental requirement is that the maximum diameter 32 of the
protrusion 31 (taken perpendicular to the longitudinal axis 12) is
larger than the inside diameter 22 of intermediate sheath 20,
necessary to enable the protrusion 31 to disrupt the intermediate
sheath 20.
[0062] FIG. 5A describes an embodiment wherein the protrusion 31 is
fundamentally spherical in shape. However, as shown by the
embodiment described in the end view of FIG. 5B, it is apparent
that the protrusion is not required to be symmetrical in transverse
cross section. As shown in FIG. 5B, the protrusion 31 may
optionally be eccentric, having a maximum diameter 32 that is
larger than a diameter taken through the longitudinal axis normal
to the maximum diameter. The protrusion 31 must have a maximum
diameter 32 that is larger than the inside diameter 22 of
intermediate sheath 20, and is thereby capable of disrupting
intermediate sheath 20 when an axial force is applied to the
protrusion 31 to cause it to move axially against and/or through
intermediate sheath 20 and endoprosthesis 11.
[0063] FIG. 5C is a longitudinal cross-section of the protrusion of
FIG. 1, wherein the protrusion is similar to the round shape of
FIG. 5A, but is provided with a more pronounced inclined plane 33,
wherein the protrusion 31 merges with the inner tube in a less
perpendicular fashion in order to reduce the axial force required
to initiate disruption of the intermediate sheath 20 and cause
expansion of the endoprosthesis 11.
[0064] FIGS. 5D and 5E are longitudinal cross-sections of
alternative embodiments of protrusion 31.
[0065] FIG. 5F is a longitudinal cross-section of an alternative
embodiment of protrusion 31 and inner tube 30, wherein the
protrusion is enlargable such as in axial compression of the
braided tubular form shown. Application of tension to a guidewire
used within the lumen of the tubular braid (guidewire omitted from
FIG. 5F for clarity) can be utilized to create the protrusion 31.
By pre-forming the protrusion at the desired site in the length of
braided wire, the location of the protrusion (along the length of
the braided wire) and its maximum diameter can be pre-determined.
In an alternative of this embodiment, the braided tubular form can
be of length about equal to or slightly greater than the length of
the constrained endoprosthesis. The entire length of this braided
tubular form (i.e., the entire length of the intermediate sheath)
can be caused to increase in diameter in a relatively uniform
fashion when axial compression is applied to the braided tubular
form by an elongate actuation member (e.g., inner tube 30) within
the tubular braided wire.
[0066] FIG. 5G is a longitudinal cross-section of the protrusion
31, wherein the protrusion is an enlargeable, inflatable member. In
another embodiment described by the longitudinal cross-section of
FIG. 5H, the protrusion of FIG. 1, the protrusion is made up of a
material dissolvable in body fluids.
[0067] FIGS. 6A and 6B are longitudinal cross-sections that show,
respectively, that protrusion 31 may be attached to, or made
integral with a guide wire 40, or other forms of elongate tensile
members such as wires of other types, cables, strands, etc. FIG. 6C
is a longitudinal cross-section indicating that protrusion 31 may
be attached to the very end of an elongate tensile member if
appropriate for particular applications.
[0068] FIG. 7A is a longitudinal cross section of a compacted and
constrained endoprosthesis incorporating a tether element 60 having
enlargement 70 at the distal end of the tether element 60, intended
to prevent unintentional axial movement of the endoprosthesis.
Enlargement 70 aids in holding the various components in the
desired axial relationship until it is desired to actually expand
and deploy endoprosthesis 11 by the use of relative tension applied
to the inner tube 30 and protrusion 31.
[0069] FIG. 7B is a transverse cross-section taken at section C-C
of FIG. 7A describing the tether element.
[0070] FIGS. 8A and 8B are longitudinal cross sections describing
alternative tethers 60 wherein the tether 60 is used to secure an
endoprosthesis 11 to another device such as a delivery catheter 25.
One or both ends of tether 60 are secured to delivery catheter 25.
One or more enlargements 70 are provided as restraints resisting
any inadvertent displacement between the catheter 25 and the
endoprosthesis 11. Tether 60 is held captive between endoprosthesis
11 and balloon 81. When balloon 81 is inflated to expand and deploy
endoprosthesis 11, the tether 60 remains captive. When balloon 81
is subsequently deflated, tether 61 is freed from endoprosthesis 11
and may be withdrawn from the body conduit into which the
endoprosthesis 11 has been inserted along with catheter 25 and
attached balloon 81.
[0071] FIG. 8C is a longitudinal cross section of a tether 60
passed through an endoprosthesis 11 that is compacted onto a
catheter balloon 81. FIG. 8C includes a side view of a hub 82 at
the proximal end of the system, showing the tether 60 having both
ends extending out of hub 82 wherein following inflation of balloon
81 and deployment of endoprosthesis 11, tether 60 may be withdrawn
by pulling on one end.
[0072] FIG. 9 is a longitudinal cross section of a compacted and
constrained endoprosthesis 11 incorporating a distensible collar 80
preferably positioned at the distal end of the endoprosthesis 11,
intended to prevent unintentional axial movement of endoprosthesis
11. Collar 80 may be a separate component affixed to the exterior
of intermediate sheath 20 at the distal end thereof, immediately
proximal to protrusion 31, or may be made to be integral to the
intermediate sheath 20. It is also apparent that the collar 80 may
simply be of the form of any sort of enlargement in the diameter of
the distal end of the intermediate sheath 20 that interferes with
axial movement of the endoprosthesis 11 and thus prevents an
unintentional movement of the endoprosthesis. As such, the
enlargement is not required to extend entirely around the
circumference of the distal end of intermediate sheath 20 in the
fashion of collar 80. Such an enlargement may be integral with the
distal end of intermediate sheath 20 or separately affixed. In an
alternative, either the collar or another form of enlargement may
be positioned beneath the endoprosthesis anywhere within the length
of the endoprosthesis, thereby making difficult any unintended
movement of the endoprosthesis with respect to the elongate tensile
member 30.
[0073] FIG. 10 is a transverse cross section taken at section D-D
of FIG. 9, describing the distensible collar 80.
[0074] FIGS. 11A and 11B are perspective views of an alternative
embodiment of the present invention wherein the substantially
tubular sheath 20 contains multiple parallel splits adjacent to its
distal end that do not extend entirely to the end. As shown by FIG.
11B, this form of the intermediate sheath 20 would increase in
diameter when the protrusion 31 is pulled against its distal end by
elongate actuation member 30, thereby exerting a radially outward
directed force against endoprosthesis 11 (not shown) and initiating
expansion and deployment of the endoprosthesis. In an alternative
embodiment shown by FIG. 11C, protrusion 31 is no longer required
and the distal end of the substantially tubular sheath is secured
to the distal end of the elongate actuation member 30, whereby
axial movement of the elongate tensile member 30 with respect to
the substantially tubular sheath 20 results in a compressive force
applied to the substantially tubular sheath 20, causing it to
deform outwardly and exert a radially outward force against the
endoprosthesis 11 (not shown) to initiate expansion and deployment
of the endoprosthesis. The distal end of elongate actuation member
30 may be secured to the distal end of the substantially tubular
sheath 20 by any of various means including compression ring 111,
or by the use of an adhesive, welding, etc.
[0075] FIGS. 12A and 12B are alternative embodiments to those of
FIGS. 11A and 11B wherein the substantially tubular sheath 20 is
made to increase in diameter in a corrugated or accordion-fashion
when protrusion 31 is moved axially against the substantially
tubular sheath 20 by the application of tension to the elongate
actuation member 30. As with the embodiment of FIG. 11C, this can
also be accomplished without requiring a protrusion 31 by securing
the distal end of the substantially tubular sheath 20 to the distal
end of the elongate actuation member 30.
[0076] While the principles of the invention have been made clear
in the illustrative embodiments set forth herein, it will be
obvious to those skilled in the art to make various modifications
to the structure, arrangement, proportion, elements, materials and
components used in the practice of the invention. For example, the
protrusion may be fitted at the proximal end of the system and
moved axially in a distal direction to initiate endoprosthesis
expansion in a proximal-to-distal direction. To the extent that
these various modifications do not depart from the spirit and scope
of the appended claims, they are intended to be encompassed
therein.
* * * * *