U.S. patent application number 13/425712 was filed with the patent office on 2012-07-12 for device and system for transcatheter mitral valve replacement.
This patent application is currently assigned to Avalon Medical, Ltd.. Invention is credited to E. Christopher Orton, Kemal Schankereli.
Application Number | 20120179244 13/425712 |
Document ID | / |
Family ID | 44146171 |
Filed Date | 2012-07-12 |
United States Patent
Application |
20120179244 |
Kind Code |
A1 |
Schankereli; Kemal ; et
al. |
July 12, 2012 |
Device and System for Transcatheter Mitral Valve Replacement
Abstract
This invention relates to the design and function of a
compressible valve replacement prosthesis which can be deployed
into a beating heart without extracorporeal circulation using a
transcatheter delivery system. The design as discussed focuses on
the deployment of a device via a minimally invasive fashion and by
way of example considers a minimally invasive surgical procedure
preferably utilizing the intercostal or subxyphoid space for valve
introduction. In order to accomplish this, the valve is formed in
such a manner that it can be compressed to fit within a delivery
system and secondarily ejected from the delivery system into the
annulus of a target valve such as a mitral valve or tricuspid
valve.
Inventors: |
Schankereli; Kemal;
(Stillwater, MN) ; Orton; E. Christopher; (Fort
Collins, CO) |
Assignee: |
Avalon Medical, Ltd.
Colorado State University Research Foundation
|
Family ID: |
44146171 |
Appl. No.: |
13/425712 |
Filed: |
March 21, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12963596 |
Dec 8, 2010 |
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13425712 |
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Current U.S.
Class: |
623/2.11 ;
623/2.18 |
Current CPC
Class: |
A61F 2230/0078 20130101;
A61F 2/848 20130101; A61F 2250/0069 20130101; A61F 2/2418 20130101;
A61F 2220/0016 20130101; A61F 2250/0018 20130101; A61F 2/2457
20130101; A61F 2230/005 20130101; A61F 2310/00023 20130101; A61F
2250/0039 20130101; A61F 2/2436 20130101; A61F 2210/0014 20130101;
A61F 2230/0054 20130101; A61F 2220/0075 20130101; A61F 2/9522
20200501 |
Class at
Publication: |
623/2.11 ;
623/2.18 |
International
Class: |
A61F 2/24 20060101
A61F002/24 |
Claims
1. A prosthetic heart valve which comprises an expandable tubular
stent having a cuff and an expandable internal leaflet assembly,
wherein said cuff is comprised of wire covered with stabilized
tissue or synthetic material, wherein said leaflet assembly is
disposed within the stent and is comprised of stabilized tissue or
synthetic material, wherein one or more tethers are attached to the
prosthetic heart valve and wherein one of such tethers is attached
to an epicardial tether securing device.
2. The prosthetic heart valve of claim 1, wherein the prosthetic
heart valve is elastic and is compressed into a delivery catheter
for deployment within a patient, and whereby upon expelling the
prosthetic heart valve from the delivery catheter, the valve
expands to its functional shape.
3. The prosthetic heart valve of claim 1, wherein the cuff wire
comprises wire from one end of the stent, wherein the cuff wire is
formed as a series of radially extending loops.
4. The prosthetic heart valve of claim 3, wherein the stent and/or
the radially extending loops of the cuff are made from
nickel-titanium alloy or a similar superelastic metal and
articulate to locally contour to the valve annulus.
5. The prosthetic heart valve of claim 4, wherein one or more of
the radially extending loops extend outwardly in various
lengths.
6. The prosthetic heart valve of claim 1, wherein the stent and
cuff are formed from the same piece of superelastic metal.
7. The prosthetic heart valve of claim 6, wherein the stent and
cuff are laser cut with pre-determined shapes to facilitate
collapsing into a catheter delivery system.
8. The prosthetic heart valve of claim 1, wherein the stabilized
tissue is derived from bovine, ovine, equine or porcine
pericardium, or from animal small intestine submucosa.
9. The prosthetic heart valve of claim 1, wherein the stabilized
tissue is derived from 30 day old bovine, ovine, equine or porcine
pericardium, or from animal small intestine submucosa.
10. The prosthetic heart valve of claim 1, wherein the synthetic
material is selected from the group consisting of polyester,
polyurethane, and polytetrafluoroethylene.
11. The prosthetic heart valve of claim 1, wherein the stabilized
tissue or synthetic material is treated with anticoagulant.
12. The prosthetic heart valve of claim 1, wherein the stabilized
tissue or synthetic material is heparinized.
13. The prosthetic heart valve of claim 1, wherein the angle of the
cuff to the stent comprises a range of between about 60 and about
150 degrees.
14. The prosthetic heart valve of claim 1, wherein the ratio of the
relationship between the height of the expanded deployed stent (h)
and the lateral distance that the cuff extends onto the cardiac
tissue (l) ranges from about 1:10 to about 10:1.
15. The prosthetic heart valve of claim 1, wherein the cuff extends
laterally beyond the wall of the expanded tubular stent between
about 8 and about 20 millimeters.
16. The prosthetic heart valve of claim 1, wherein the epicardial
securing device is a pledget, button or similar device located on
the outer surface of the apical epicardium, to which one or more
tethers are attached.
17. The prosthetic heart valve of claim 1, wherein the tubular
stent has a first end and a second end, wherein the cuff is
connected to the tubular stent at the first end of the tubular
stent, and the second end of the tubular stent has a plurality of
tether attachment structures.
18. The prosthetic heart valve of claim 1, further comprising a
plurality of tethers attached to the prosthetic heart valve for
anchoring the prosthetic heart valve to native tissue.
19. The prosthetic heart valve of claim 18, wherein at least one of
the plurality of tethers is an elastic tether.
20. The prosthetic heart valve of claim 18, wherein at least one of
the plurality of tethers is a bioresorbable tether.
21. The prosthetic heart valve of claim 18, wherein at least one of
the plurality of tethers is a positioning tether and at least one
of the plurality of tethers is an anchoring tether.
22. The prosthetic heart valve of claim 1, wherein the cuff is
connected to a plurality of tethers.
23. The prosthetic heart valve of claim 22, wherein at least one of
the plurality of tethers is an elastic tether.
24. The prosthetic heart valve of claim 22, wherein at least one of
the plurality of tethers is a bioresorbable tether.
25. The prosthetic heart valve of claim 22, wherein at least one of
the plurality of tethers is a positioning tether and at least one
of the plurality of tethers is an anchoring tether.
26. The prosthetic heart valve of claim 1, further comprising at
least one tether attached to the cuff and/or at least one tether
attached to the stent body.
27. The prosthetic heart valve of claim 26, wherein at least one of
the plurality of tethers is an elastic tether.
28. The prosthetic heart valve of claim 26, wherein at least one of
the plurality of tethers is a bioresorbable tether.
29. The prosthetic heart valve of claim 26, wherein at least one of
the plurality of tethers is a positioning tether and at least one
of the plurality of tethers is an anchoring tether.
30. The prosthetic heart valve of claim 29, wherein at least one of
the plurality of tethers is an elastic tether.
31. The prosthetic heart valve of claim 29, wherein at least one of
the plurality of tethers is a bioresorbable tether.
32. The prosthetic heart valve of claim 1, further comprising a
plurality of anchoring barbs attached to the prosthetic heart valve
for anchoring the valve into local tissue.
33. The prosthetic heart valve of claim 1, wherein the leaflet
assembly is constructed solely of stabilized tissue or synthetic
material without a separate wire support structure, wherein the
leaflet assembly comprises a plurality of valve leaflets attached
to a leaflet housing, wherein the leaflet assembly is disposed
within the lumen of the stent and is attached to the stent to
provide a sealed joint between the leaflet assembly and the inner
wall of the stent.
34. The prosthetic heart valve of claim 1, wherein the leaflet
assembly comprises a leaflet wire support structure to which a
plurality of valve leaflets are attached and the entire leaflet
assembly is housed within the stent body, wherein the leaflets are
made from stabilized tissue or synthetic material, wherein the
leaflet wire support is made from a superelastic metal, and wherein
the leaflet assembly is disposed within the lumen of the stent and
is attached to the stent to provide a sealed joint between the
leaflet assembly and the inner wall of the stent.
35. The leaflet assembly according to claim 33, wherein the leaflet
assembly is shaped to have a hyperbolic paraboloid shape defining
commissural points.
36. A cuff for a prosthetic heart valve wherein the cuff has an
articulating structure made of a superelastic metal that is covered
with stabilized tissue or synthetic material.
37. The cuff of claim 36, wherein the articulating structure
comprises a plurality of radially extending loops.
38. The cuff of claim 37, wherein the radially extending loops
extend outwardly in various lengths.
39. The cuff of claim 36, wherein the superelastic metal is a
nickel-titanium alloy.
40. The cuff of claim 36, wherein the stabilized tissue is derived
from bovine, ovine, equine or porcine pericardium, or from animal
small intestine submucosa.
41. The cuff of claim 36, wherein the stabilized tissue is derived
from 30 day old bovine, ovine, equine or porcine pericardium, or
from animal small intestine submucosa.
42. The cuff of claim 36, wherein the synthetic material is
selected from the group consisting of polyester, polyurethane, and
polytetrafluoroethylene.
43. The cuff of claim 36, wherein the stabilized tissue or
synthetic material is treated with anticoagulant.
44. The cuff of claim 36, wherein the stabilized tissue or
synthetic material is heparinized.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
application Ser. No. 61/267,739, filed Dec. 8, 2009, which is
incorporated herein by reference in its entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] No federal government funds were used in researching or
developing this invention.
NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT
[0003] Not applicable.
SEQUENCE LISTING INCLUDED AND INCORPORATED BY REFERENCE HEREIN
[0004] Not applicable.
BACKGROUND
[0005] 1. Field of the Invention
[0006] This invention relates to a transcatheter mitral valve
replacement and a delivery system therefor.
[0007] 2. Background of the Invention
[0008] The current state of knowledge is as follows.
[0009] Valvular heart disease and specifically aortic and mitral
valve disease is a significant health issue in the US Annually
approximately 90,000 valve replacements are conducted in the US.
Traditional valve replacement surgery, the orthotopic replacement
of a heart valve, is an "open heart" surgical procedure. Briefly,
the procedure necessitates surgical opening of the thorax, the
initiation of extra-corporeal circulation with a heart-lung
machine, stopping and opening the heart, excision and replacement
of the diseased valve, and re-starting of the heart. While valve
replacement surgery typically carries a 1-4% mortality risk in
otherwise healthy persons, a significantly higher morbidity is
associated to the procedure largely due to the necessity for
extra-corporeal circulation. Further, open heart surgery is often
poorly tolerated in elderly patients.
[0010] Thus if the extra-corporeal component of the procedure could
be eliminated, morbidities and cost of valve replacement therapies
would be significantly reduced.
[0011] While replacement of the aortic valve in a transcatheter
manner is the subject of intense investigation, lesser attention
has been focused on the mitral valve. This is in part reflective of
the greater level of complexity associated to the native mitral
valve apparatus and thus a greater level of difficulty with regards
to inserting and anchoring the replacement prosthesis.
[0012] Several designs for catheter-deployed (transcatheter) aortic
valve replacement are under various stages of development. The
Edwards SAPIEN transcatheter heart valve is currently undergoing
clinical trial in patients with calcific aortic valve disease who
are considered high-risk for conventional open-heart valve surgery.
This valve is deployable via a retrograde transarterial
(transfemoral) approach or an antegrade transapical
(trans-ventricular) approach. A key aspect of the Edwards SAPIEN
and other transcatheter aortic valve replacement designs is their
dependence on lateral fixation (e.g. tines) that engages the valve
tissues as the primary anchoring mechanism. Such a design basically
relies on circumferential friction around the valve housing or
stent to prevent dislodgement during the cardiac cycle. This
anchoring mechanism is facilitated by, and may somewhat depend on,
a calcified aortic valve annulus. This design also requires that
the valve housing or stent have a certain degree of rigidity.
[0013] At least one transcatheter mitral valve design is currently
in development. The Endovalve uses a folding tripod-like design
that delivers a tri-leaflet bioprosthetic valve. It is designed to
be deployed from a minimally invasive transatrial approach, and
could eventually be adapted to a transvenous atrial septotomy
delivery. This design uses "proprietary gripping features" designed
to engage the valve annulus and leaflets tissues. Thus the
anchoring mechanism of this device is essentially equivalent to
that used by transcatheter aortic valve replacement designs.
BRIEF SUMMARY OF THE INVENTION
[0014] The present invention relates to the design and function of
a compressible prosthetic heart valve replacement which can be
deployed into a closed beating heart using a transcatheter delivery
system. The design as discussed focuses on the deployment of a
device via a minimally invasive fashion and by way of example
considers a minimally invasive surgical procedure utilizing the
intercostal or subxyphoid space for valve introduction. In order to
accomplish this, the valve is formed in such a manner that it can
be compressed to fit within a delivery system and secondarily
ejected from the delivery system into the target location, for
example the mitral or tricuspid valve annulus.
[0015] In a preferred embodiment, there is provided a prosthetic
mitral valve containing a cuff which locally contours to the mitral
annulus.
[0016] In another preferred embodiment, there is provided a
prosthetic heart valve with a cuff that has a tissue or synthetic
covering.
[0017] In another preferred embodiment, there is provided a
prosthetic heart valve with a cuff that has articulating wire loops
of various lengths.
[0018] In another preferred embodiment, there is provided a
prosthetic heart valve containing at least one elastic tether to
provide compliance during the physiologic movement or
conformational changes associated with heart contraction.
[0019] In another preferred embodiment, there is provided a
prosthetic heart valve having a stent body and cuff that are made
from a superelastic metal.
[0020] In another preferred embodiment, there is provided a
prosthetic heart valve having a stent body and cuff that are made
from a superelastic metal that is laser cut with predetermined
shapes to facilitate collapsing into the catheter delivery
system.
[0021] In another preferred embodiment, there is provided a
prosthetic heart valve having a stent body constructed from ductile
metal, for example stainless steel, so as to require a balloon for
expansion once located at the annulus, but capable of deformation
without fracture.
[0022] In another preferred embodiment, there is provided a
prosthetic heart valve constructed from superelastic wire made from
a shape memory alloy such as nickel-titanium alloy (Naval Ordinance
Lab) Nitinol.TM..
[0023] In another preferred embodiment, there is provided a laser
cut prosthetic heart valve containing tethers for anchoring.
[0024] In another preferred embodiment, there is provided a valve
constructed from wire containing tethers for anchoring.
[0025] In another preferred embodiment, there is provided a valve
containing tether which are used to position the valve cuff into
the mitral annulus to prevent perivalvular leak.
[0026] In another preferred embodiment, there are tethers that are
bioabsorbable and provide temporary anchoring until biological
fixation of the prosthesis occurs. Biological fixation consisting
of fibrous adhesions between the leaflet tissues and prosthesis or
compression on the prosthesis by reversal of heart dilation, or
both.
[0027] In another preferred embodiment, there is provided a
prosthetic heart valve constructed from wire or laser-formed
demonstrating a compliant body and cuff such that the two
components accommodate the movement of the heart throughout the
cardiac cycle.
[0028] In another preferred embodiment, there is provided a cuff
for a prosthetic heart valve, said cuff being covered with
tissue.
[0029] In another preferred embodiment, there is provided a cuff
for a prosthetic heart valve, said cuff being covered with a
synthetic polymer selected from expandable polytetrafluoroethylene
(ePTFE) or polyester.
[0030] In another preferred embodiment, there is provided a
prosthetic heart valve that has leaflet material constructed from a
material selected from the group consisting of polyurethane,
polytetrafluoroethylene, pericardium, and small intestine
submucosa.
[0031] In another preferred embodiment, there is provided a
prosthetic heart valve having surfaces that are treated with
anticoagulant.
[0032] In another preferred embodiment, there is provided a
prosthetic heart valve having a cuff and containing anchoring
tethers which are attached to the cuff.
[0033] In another preferred embodiment, there is provided a
prosthetic heart valve having a cuff and containing anchoring
tethers which are attached to the cuff and at both commissural
tips.
[0034] In another preferred embodiment, there is provided a
prosthetic heart valve having a cuff where the cuff attachment
relative to the body is within the angles of about 60 degrees to
about 150 degrees.
[0035] In another preferred embodiment, there is provided a
prosthetic heart valve containing a combination of tethers and
barbs useful for anchoring the device into the mitral annulus.
[0036] In a preferred embodiment, there is provided a prosthetic
heart valve which comprises an expandable tubular stent having a
cuff and an expandable internal leaflet assembly, said leaflet
assembly may or may not have a structural wire support, wherein
said cuff is comprised of wire covered with stabilized tissue, and
wherein said leaflet assembly is disposed within the stent and is
comprised of stabilized tissue in the form of leaflets.
[0037] In another embodiment, there is provided a feature wherein
the wire of the cuff is formed as a series of radially extending
loops of equal or variable length.
[0038] In another embodiment, there is provided a feature wherein
the cuff extends laterally beyond the expanded tubular stent
according to a ratio of the relationship between the height of the
expanded deployed stent (h) and the lateral distance that the cuff
extends onto the tissue (1). Preferably, the h/1 ratio can range
from 1:10 to 10:1, and more preferably includes without limitation
1:3, 1:2, 1:1, 2:1, and fractional ranges there between such as
1.25:2.0, 1.5:2.0, and so forth. It is contemplated in one
non-limiting example that the cuff can extend laterally (1) between
about 3 and about 30 millimeters.
[0039] In another embodiment, there is provided a feature wherein
the tubular stent has a first end and a second end, wherein the
cuff is formed from the stent itself, or in the alternative is
formed separately and wherein the cuff is located at the first end
of the stent, and the second end of the tubular stent has a
plurality of tether attachment structures.
[0040] In another embodiment, there is provided a feature further
comprising a plurality of tethers for anchoring the prosthetic
heart valve to tissue and/or for positioning the prosthetic heart
valve.
[0041] In another embodiment, there is provided a feature further
comprising an epicardial tether securing device, wherein the
tethers extend between about 3 and about 8 cm in length, and are
fastened to an epicardial tether securing device.
[0042] In another embodiment, there is provided a catheter delivery
system for delivery of a prosthetic heart valve which comprises a
delivery catheter having the prosthetic heart valve disposed
therein, and an obturator for expelling the prosthetic heart
valve.
[0043] In another embodiment, there is provided an assembly kit for
preparing the catheter delivery system which comprises a
compression funnel, an introducer, a wire snare, an obturator, a
delivery catheter, and a prosthetic heart valve, wherein the
compression funnel has an aperture for attaching to the introducer,
wherein said introducer is comprised of a tube having a diameter
that fits within the diameter of the delivery catheter, whereinsaid
obturator is comprised of a tube fitted with a handle at one end
and a cap at the other end, whereinhere said cap has an opening to
allow the wire snare to travel therethrough, and said obturator has
a diameter that fits within the diameter of the introducer, and
wherein said prosthetic heart valve is compressible and fits within
the delivery catheter.
[0044] In another embodiment, there is provided a method of
treating mitral regurgitation and/or tricuspid regurgitation in a
patient, which comprises the step of surgically deploying the
prosthetic heart valve into the annulus of the target valve
structure, e.g. mitral valve annulus and tricuspid valve annulus of
the patient.
[0045] In another embodiment, there is provided a feature wherein
the prosthetic heart valve is deployed by directly accessing the
heart through an intercostal space, using an apical approach to
enter the left (or right) ventricle, and deploying the prosthetic
heart valve into the valvular annulus using the catheter delivery
system.
[0046] In another embodiment, there is provided a feature wherein
the prosthetic heart valve is deployed by directly accessing the
heart through a thoracotomy, sternotomy, or minimally-invasive
thoracic, thorascopic, or transdiaphragmatic approach to enter the
left (or right) ventricle, and deploying the prosthetic heart valve
into the valvular annulus using the catheter delivery system.
[0047] In another embodiment, there is provided a feature wherein
the prosthetic heart valve is deployed by directly accessing the
heart through the intercostal space, using a lateral approach to
enter the left or right ventricle, and deploying the prosthetic
heart valve into the valvular annulus using the catheter delivery
system.
[0048] In another embodiment, there is provided a feature wherein
the prosthetic heart valve is deployed by accessing the left heart
using either an antegrade-trans(atrial)septal
(transvenous-trans(atrial)septal) approach or a retrograde
(transarterial-transaortic) catheter approach to enter the left
heart, and deploying the prosthetic heart valve into the mitral
annulus using the catheter delivery system.
[0049] In another embodiment, there is provided a feature wherein
the prosthetic heart valve is deployed into the mitral annulus from
a retrograde approach by accessing the left ventricle through the
apex of the ventricular septum
(transvenous-trans(ventricular)septal approach).
[0050] In another embodiment, there is a feature wherein the
prosthetic heart valve is deployed into the mitral position using a
retrograde transventricular septal approach and the tethers are
anchored into or on the right ventricular side of the ventricular
septum.
[0051] In another embodiment, there is provided a feature further
comprising tethering the prosthetic heart valve to tissue within
the left ventricle.
[0052] In another embodiment, there is provided a feature wherein
the prosthetic heart valve is tethered to the apex of the left
ventricle using an epicardial tether securing device. In another
embodiment, such device is fashioned as a pledget, button or
similar article.
[0053] In another embodiment, there is provided a retrieval method
for quickly removing a prosthetic heart valve having one or more
tethers from a patient using minimally invasive cardiac catheter
techniques, which comprises the steps of, capturing the one or more
tethers with a catheter having a snare attachment, guiding the
captured tethers into a collapsible funnel attachment connected to
the removal catheter, pulling the tethers to conform the prosthetic
heart valve into a collapsed, compressed conformation, and pulling
the now compressed prosthetic heart valve into the removal catheter
for subsequent extraction. The retrieval method is contemplated for
use for capturing the prosthetic heart valve as described herein or
any suitable tethered, collapsible medical device. In a preferred
embodiment, the method is used to extract a prosthetic heart valve
from either the left or right ventricle. The method may be
particularly useful to extract the prosthetic appliance during an
aborted surgical deployment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0054] FIG. 1 is a perspective view of one embodiment of a
prosthetic valve according to the present invention.
[0055] FIG. 2 A-D is a perspective exploded view of one embodiment
of a prosthetic valve according to the present invention that does
not use a structural wire support for the valve cusps/leaflets.
[0056] FIG. 3 A-E is a perspective exploded view of one embodiment
of a prosthetic valve according to the present invention that
incorporates a structural wire support for the valve
cusps/leaflets.
[0057] FIG. 4 is a top view of on embodiment of a prosthetic valve
according to the present invention and shows a two-leaflet
structure.
[0058] FIG. 5 is a side view from slightly below the horizontal
plane of one embodiment of a prosthetic valve according to the
present invention to show the bottom surface of the cuff. FIG. 5
shows the tethers without the structural wire support for the
leaflets.
[0059] FIG. 6 is a top view from slightly above the horizontal
plane of one embodiment of a prosthetic valve according to the
present invention and shows the top surface of the cuff and
structural wire support loops extending beyond the length of the
stent.
[0060] FIG. 7 is a view of one embodiment of a prosthetic valve
according to the present invention showing that the cuff spindles
may optionally have variable lengths and sizes.
[0061] FIG. 8 is a view of one embodiment of a prosthetic valve
according to the present invention showing that the cuff spindles
may optionally have variable lengths and sizes. Here they are shown
to create an elongated cuff.
[0062] FIG. 9 is a top view of one embodiment of a prosthetic valve
according to the present invention showing a three-leaflet
structure.
[0063] FIG. 10 A-C is a series of side views of one embodiment of a
prosthetic valve according to the present invention illustrating
that the cuff may be formed to have an original configuration
whereby the cuffs disposition relative to the stent body has an
acute, right, or obtuse angle.
[0064] FIG. 11 is a side view of one embodiment of a prosthetic
valve according to the present invention illustrating the use of a
barb component to assist seating the prosthetic valve in the
valvular annulus.
[0065] FIG. 12 A-B is a pair of side views of one embodiment of a
prosthetic valve according to the present invention illustrating
the use of a barb component which is open but then closes upon or
into the annular tissue when the stent body is expanded to assist
seating the prosthetic valve in the valvular annulus.
[0066] FIG. 13 is a side view of one embodiment of a prosthetic
valve according to the present invention showing tethers attached
to the cuff portion in addition to attachment on the stent
body.
[0067] FIG. 14 is a drawing of one embodiment of the delivery
system equipment according to the present invention used to
compress and deploy the prosthetic valve.
[0068] FIG. 15 A-F is a series of drawings of one embodiment of the
delivery system according to the present invention.
[0069] FIG. 16 is a detailed sectional view of an embodiment of a
delivery catheter, and one embodiment of a compressed prosthetic
valve according to the present invention disposed within the
delivery catheter.
[0070] FIG. 17 is a cut-away view of a heart with a delivery
catheter containing a prosthetic valve according to the present
invention and accessing the heart using an apical approach. FIG. 17
shows the delivery catheter advanced to through the mitral valve
and into the left atrium for deployment of the prosthetic
valve.
[0071] FIG. 18 A-D is a series of views of the tip of one
embodiment of a delivery catheter according to the present
invention containing a pre-loaded prosthetic valve which is being
pushed out of the delivery catheter, i.e. by an obturator, starting
with (A) the valve completely within the catheter, (B) the cuff
portion being in view, (C) the stent body following, and (D) the
prosthetic valve with attached tethers for positioning and/or
adjustment and/or securing the valve to tissue.
[0072] FIG. 19 is a detailed sectional view of one embodiment of a
prosthetic valve according to the present invention deployed within
the annulus of the mitral valve of the heart and shows that it is
anchored using (a) the atrial cuff and (b) the ventricular tethers
connected to the apex, which are shown secured by a securing
pledget.
[0073] FIG. 20 is a detailed side-perspective view of one
embodiment of a prosthetic valve according to the present invention
deployed within the annulus of the mitral valve of the heart and
anchored using (a) the atrial cuff and (b) the ventricular tethers
connected to papillary muscles and/or ventricular wall and/or
septum, which are each secured by one or more securing tissue
anchors.
[0074] FIG. 21 A-B is a pair of drawings showing one embodiment of
a ventricular tether attachment according to the present invention.
FIG. 21 A is a detailed drawing of the flexible delivery catheter
inserted into the left ventricular apex along with four sutures
having partially installed apical-closure/tissue-buttressing
material. FIG. 21 B is a detailed drawing of the anchoring system
of the prosthetic valve in which the ventricular tethers are shown
treaded through the left ventricle apex and through a partially
installed pledget; also shown are fully installed apical-closure
material.
[0075] FIG. 22 A-B is a pair of drawings of the lateral deployment
of one embodiment of a prosthetic valve according to the present
invention. FIG. 22B is a detail view of an illustration of the
prosthetic valve seated within the mitral annulus and tethered to
the papillary muscles of the left ventricle.
[0076] FIG. 23 is a cut-away view of a heart with a delivery
catheter containing a prosthetic valve according to the present
invention and accessing the right ventricle of the heart using an
apical approach. FIG. 23 shows the delivery catheter advanced
through to the tricuspid valve and into the right atrium for
deployment of the prosthetic valve.
[0077] FIG. 24 A-B shows an embodiment of a prosthetic valve having
a ring or halo feature. FIG. 24A is a bottom view from slightly
above the horizontal plane of one embodiment of a prosthetic valve
according to the present invention to show the bottom surface of
the cuff and the halo feature. FIG. 24B is a top view from slightly
above the horizontal plane of one embodiment of a prosthetic valve
according to the present invention to show the top surface of the
cuff.
DETAILED DESCRIPTION OF THE INVENTION
[0078] The present invention provides in one embodiment a
prosthetic heart valve that comprises a self-expanding valve
assembly that is anchored within the mitral valve of the heart
using an integral cuff to anchor the valve and using one or more
tethers anchored to the heart. It is contemplated as within the
scope of the invention to provide a prosthetic heart valve having
as an anchoring system both an integral cuff or collar and one or
more tethers for tissue anchoring.
[0079] The prosthetic heart valve comprises a self-expanding
tubular stent having a cuff at one end and tether loops for
attaching tethers at the other end, and disposed within the tubular
stent is a leaflet assembly that contains the valve leaflets, the
valve leaflets being formed from stabilized tissue or other
suitable biological or synthetic material. In one embodiment, the
leaflet assembly comprises a wire form where a formed wire
structure is used in conjunction with stabilized tissue to create a
leaflet support structure which can have anywhere from 1, 2, 3 or 4
leaflets, or valve cusps disposed therein. In another embodiment,
the leaflet assembly is wireless and uses only the stabilized
tissue and stent body to provide the leaflet support structure,
without using wire, and which can also have anywhere from 1, 2, 3
or 4 leaflets, or valve cusps disposed therein.
Functions of the Cuff
[0080] The cuff functions in a variety of ways. The first function
of the cuff is to inhibit perivalvular leak/regurgitation of blood
around the prosthesis. By flexing and sealing across the irregular
contours of the annulus and atrium, leaking is minimized and/or
prevented.
[0081] The second function of the cuff is to provide an adjustable
and/or compliant bioprosthetic valve. The heart and its structures
undergo complex conformational changes during the cardiac cycle.
For example, the mitral valve annulus has a complex geometric shape
known as a hyperbolic parabloid much like a saddle, with the horn
being anterior, the seat back being posterior, and the left and
right valleys located medially and laterally. Beyond this
complexity, the area of the mitral annulus changes over the course
of the cardiac cycle. Further, the geometry of the tricuspid valve
and tricuspid annulus continues to be a topic of research, posing
its own particular problems. Accordingly, compliance is a very
important but unfortunately often overlooked requirement of cardiac
devices. Compliance here refers to the ability of the valve to
maintain structural position and integrity during the cardiac
cycle. Compliance with the motion of the heart is a particularly
important feature, especially the ability to provide localized
compliance where the underlying surfaces are acting differently
from the adjacent surfaces. This ability to vary throughout the
cardiac cycle allows the valve to remain seated and properly
deployed in a manner not heretofore provided.
[0082] Additionally, compliance may be achieved through the use of
the tethers where the tethers are preferably made from an elastic
material. Tether-based compliance may be used alone, or in
combination with the cuff-based compliance.
[0083] The third function of the cuff valve is to provide a valve
that, during surgery, is able to be seated and be able to contour
to the irregular surfaces of the atrium. The use of independent
tethers allows for side to side fitting of the valve within the
annulus. For example, where three tethers are used, they are
located circumferentially about 120 degrees relative to each other
which allows the surgeon to observe whether or where perivalvular
leaking might be occurring and to pull on one side or the other to
create localized pressure and reduce or eliminate the leaking.
[0084] The forth function of the cuff is to counter the forces that
act to displace the prosthesis toward/into the ventricle (i.e.
atrial pressure and flow-generated shear stress) during ventricular
filling.
[0085] Additional features of the cuff include that it functions to
strengthen the leaflet assembly/stent combination by providing
additional structure. Further, during deployment, the cuff
functions to guide the entire structure, the prosthetic valve, into
place at the mitral annulus during deployment and to keep the valve
in place once it is deployed.
Cuff Structure
[0086] The cuff is a substantially flat plate that projects beyond
the diameter of the tubular stent to form a rim or border. As used
herein, the term cuff, flange, collar, bonnet, apron, or skirting
are considered to be functionally equivalent. When the tubular
stent is pulled through the mitral valve aperture, the mitral
annulus, by the tether loops in the direction of the left
ventricle, the cuff acts as a collar to stop the tubular stent from
traveling any further through the mitral valve aperture. The entire
prosthetic valve is held by longitudinal forces between the cuff
which is seated in the left atrium and mitral annulus, and the
ventricular tethers attached to the left ventricle.
[0087] The cuff is formed from a stiff, flexible shape-memory
material such as the nickel-titanium alloy material Nitinol.TM.
wire that is covered by stabilized tissue or other suitable
biocompatible or synthetic material. In one embodiment, the cuff
wire form is constructed from independent loops of wire that create
lobes or segments extending axially around the circumference of the
bend or seam where the cuff transitions to the tubular stent (in an
integral cuff) or where the cuff is attached to the stent (where
they are separate, but joined components).
[0088] Once covered by stabilized tissue or material, the loops
provide the cuff the ability to travel up and down, to articulate,
along the longitudinal axis that runs through the center of the
tubular stent. In other words, the individual spindles or loops can
independently move up and down, and can spring back to their
original position due to the relative stiffness of the wire. The
tissue or material that covers the cuff wire has a certain modulus
of elasticity such that, when attached to the wire of the cuff, is
able to allow the wire spindles to move. This flexibility gives the
cuff, upon being deployed within a patient's heart, the ability to
conform to the anatomical shape necessary for a particular
application. In the example of a prosthetic mitral valve, the cuff
is able to conform to the irregularities of the left atrium and
shape of the mitral annulus, and to provide a tight seal against
the atrial tissue adjacent the mitral annulus and the tissue within
the mitral annulus. As stated previously, this feature importantly
provides a degree of flexibility in sizing the a mitral valve and
prevents blood from leaking around the implanted prosthetic heart
valve.
[0089] An additional important aspect of the cuff dimension and
shape is that, when fully seated and secured, the edge of the cuff
preferably should not be oriented laterally into the atrial wall
such that it can produce a penetrating or cutting action on the
atrial wall. In one preferred embodiment, the wire spindles of the
cuff are substantially uniform in shape and size. In another
preferred embodiment of the present invention, each loop or spindle
may be of varying shapes and sizes. In this example, it is
contemplated that the loops may form a pattern of alternating large
and small loops, depending on where the valve is being deployed. In
the case of a prosthetic mitral valve, pre-operative imaging may
allow for customizing the structure of the cuff depending on a
particular patient's anatomical geometry in the vicinity of the
mitral annulus.
[0090] The cuff wire form is constructed so as to provide
sufficient structural integrity to withstand the intracardiac
forces without collapsing. The cuff wire form is preferably
constructed of a superelastic metal, such as Nitinol.TM..RTM. and
is capable of maintaining its function as a sealing collar for the
tubular stent while under longitudinal forces that might cause a
structural deformation or valve displacement. It is contemplated as
within the scope of the invention to optionally use other shape
memory alloys such as Cu--Zn--Al--Ni alloys, and Cu--Al--Ni alloys.
The heart is known to generate an average left atrial pressure
between about 8 and 30 mm Hg (about 0.15 to 0.6 psi). This left
atrial filling pressure is the expected approximate pressure that
would be exerted in the direction of the left ventricle when the
prosthesis is open against the outer face of the cuff as an
anchoring force holding the cuff against the atrial tissue that is
adjacent the mitral valve. The cuff counteracts this longitudinal
pressure against the prosthesis in the direction of the left
ventricle to keep the valve from being displaced or slipping into
the ventricle. In contrast, left ventricular systolic pressure,
normally about 120 mm Hg, exerts a force on the closed prosthesis
in the direction of the left atrium. The tethers counteract this
force and are used to maintain the valve position and withstand the
ventricular force during ventricular contraction or systole.
Accordingly, the cuff has sufficient structural integrity to
provide the necessary tension against the tethers without being
dislodged and pulled into the left ventricle. After a period of
time, changes in the geometry of the heart and/or fibrous adhesion
between prosthesis and surrounding cardiac tissues may assist or
replace the function of the ventricular tethers in resisting
longitudinal forces on the valve prosthesis during ventricular
contraction.
Stent Structure
[0091] Preferably, superelastic metal wire, such as Nitinol.TM.
wire, is used for the stent, for the inner wire-based leaflet
assembly that is disposed within the stent, and for the cuff wire
form. As stated, it is contemplated as within the scope of the
invention to optionally use other shape memory alloys such as
Cu--Zn--Al--Ni alloys, and Cu--Al--Ni alloys. It is contemplated
that the stent may be constructed as a braided stent or as a laser
cut stent. Such stents are available from any number of commercial
manufacturers, such as Pulse Systems. Laser cut stents are
preferably made from Nickel-Titanium (Nitinol.TM.), but also
without limitation made from stainless steel, cobalt chromium,
titanium, and other functionally equivalent metals and alloys, or
Pulse Systems braided stent that is shape-set by heat treating on a
fixture or mandrel.
[0092] One key aspect of the stent design is that it be
compressible and when released have the stated property that it
return to its original (uncompressed) shape. This requirement
limits the potential material selections to metals and plastics
that have shape memory properties. With regards to metals, Nitinol
has been found to be especially useful since it can be processed to
be austhenitic, martensitic or super elastic. Martensitic and super
elastic alloys can be processed to demonstrate the required
compression features.
Laser Cut Stent
[0093] One possible construction of the stent envisions the laser
cutting of a thin, isodiametric Nitinol tube. The laser cuts form
regular cutouts in the thin Nitinol tube. Secondarily the tube is
placed on a mold of the desired shape, heated to the Martensitic
temperature and quenched. The treatment of the stent in this manner
will form a stent or stent/cuff that has shape memory properties
and will readily revert to the memory shape at the calibrated
temperature.
Braided Wire Stent
[0094] A stent can be constructed utilizing simple braiding
techniques. Using a Nitinol wire--for example a 0.012'' wire--and a
simple braiding fixture, the wire is wound on the braiding fixture
in a simple over/under braiding pattern until an isodiametric tube
is formed from a single wire. The two loose ends of the wire are
coupled using a stainless steel or Nitinol coupling tube into which
the loose ends are placed and crimped. Angular braids of
approximately 60 degrees have been found to be particularly useful.
Secondarily, the braided stent is placed on a shaping fixture and
placed in a muffle furnace at a specified temperature to set the
stent to the desired shape and to develop the martensitic or super
elastic properties desired.
[0095] The stent as envisioned in one preferred embodiment is
designed such that the ventricular aspect of the stent comes to 2-5
points onto which anchoring sutures are affixed. The anchoring
sutures (tethers) will traverse the ventricle and ultimately be
anchored to the epicardial surface of the heart approximately at
the level of the apex. The tethers when installed under slight
tension will serve to hold the valve in place, i.e. inhibit
paravalvular leakage during systole.
Leaflet and Assembly Structure
[0096] The valve leaflets are held by, or within, a leaflet
assembly. In one preferred embodiment of the invention, the leaflet
assembly comprises a leaflet wire support structure to which the
leaflets are attached and the entire leaflet assembly is housed
within the stent body. In this embodiment, the assembly is
constructed of wire and stabilized tissue to form a suitable
platform for attaching the leaflets. In this aspect, the wire and
stabilized tissue allow for the leaflet structure to be compressed
when the prosthetic valve is compressed within the deployment
catheter, and to spring open into the proper functional shape when
the prosthetic valve is opened during deployment. In this
embodiment, the leaflet assembly may optionally be attached to and
housed within a separate cylindrical liner made of stabilized
tissue or material, and the liner is then attached to line the
interior of the stent body.
[0097] In this embodiment, the leaflet wire support structure is
constructed to have a collapsible/expandable geometry. In a
preferred embodiment, the structure is a single piece of wire. The
wireform is, in one embodiment, constructed from a shape memory
alloy such as Nitinol. The structure may optionally be made of a
plurality of wires, including between 2 to 10 wires. Further, the
geometry of the wire form is without limitation, and may optionally
be a series of parabolic inverted collapsible arches to mimic the
saddle-like shape of the native annulus when the leaflets are
attached. Alternatively, it may optionally be constructed as
collapsible concentric rings, or other similar geometric forms that
are able to collapse/compress which is followed by an expansion to
its functional shape. In certain preferred embodiments, there may
be 2, 3 or 4 arches. In another embodiment, closed circular or
ellipsoid structure designs are contemplated. In another
embodiment, the wire form may be an umbrella-type structure, or
other similar unfold-and-lock-open designs. A preferred embodiment
utilizes super elastic Nitinol wire approximately 0.015'' in
diameter. In this embodiment, the wire is wound around a shaping
fixture in such a manner that 2-3 commissural posts are formed. The
fixture containing the wrapped wire is placed in a muffle furnace
at a pre-determined temperature to set the shape of the wire form
and to impart it's super elastic properties. Secondarily, the loose
ends of the wireform are joined with a stainless steel or Nitinol
tube and crimped to form a continuous shape. In another preferred
embodiment, the commissural posts of the wireform are adjoined at
their tips by a circular connecting ring, or halo, whose purpose is
to minimize inward deflection of the post(s).
[0098] In another preferred embodiment, the leaflet assembly is
constructed solely of stabilized tissue or other suitable material
without a separate wire support structure. The leaflet assembly in
this embodiment is also disposed within the lumen of the stent and
is attached to the stent to provide a sealed joint between the
leaflet assembly and the inner wall of the stent. By definition, it
is contemplated within the scope of the invention that any
structure made from stabilized tissue and/or wire(s) related to
supporting the leaflets within the stent constitute a leaflet
assembly.
[0099] In this embodiment, stabilized tissue or suitable material
may also optionally be used as a liner for the inner wall of the
stent and is considered part of the leaflet assembly. Liner tissue
or biocompatible material may be processed to have the same or
different mechanical qualities, e.g. thickness, durability, etc.
from the leaflet tissue.
Deployment within the Valvular Annulus
[0100] The prosthetic heart valve is, in one embodiment, apically
delivered through the apex of the left ventricle of the heart using
a catheter system. In one aspect of the apical delivery, the
catheter system accesses the heart and pericardial space by
intercostal delivery. In another delivery approach, the catheter
system delivers the prosthetic heart valve using either an
antegrade or retrograde delivery approach using a flexible catheter
system, and without requiring the rigid tube system commonly used.
In another embodiment, the catheter system accesses the heart via a
trans-septal approach.
[0101] In one non-limiting preferred embodiment, the stent body
extends into the ventricle about to the edge of the open mitral
valve leaflets (approximately 25% of the distance between the
annulus and the ventricular apex). The open native leaflets lay
against the outside stent wall and parallel to the long axis of the
stent (i.e. the stent holds the native mitral valve open).
[0102] In one non-limiting preferred embodiment, the diameter
should approximately match the diameter of the mitral annulus.
Optionally, the valve may be positioned to sit in the mitral
annulus at a slight angle directed away from the aortic valve such
that it is not obstructing flow through the aortic valve.
Optionally, the outflow portion (bottom) of the stent should not be
too close to the lateral wall of the ventricle or papillary muscle
as this position may interfere with flow through the prosthesis. As
these options relate to the tricuspid, the position of the
tricuspid valve may be very similar to that of the mitral
valve.
[0103] In another embodiment, the prosthetic valve is sized and
configured for use in areas other than the mitral annulus,
including, without limitation, the tricuspid valve between the
right atrium and right ventricle. Alternative embodiments may
optionally include variations to the cuff structure to accommodate
deployment to the pulmonary valve between the right ventricle and
pulmonary artery, and the aortic valve between the left ventricle
and the aorta. In one embodiment, the prosthetic valve is
optionally used as a venous backflow valve for the venous system,
including without limitation the vena cava, femoral, subclavian,
pulmonary, hepatic, renal and cardiac. In this aspect, the cuff
feature is utilized to provide additional protection against
leaking
Tethers
[0104] In one preferred embodiment, there are tethers attached to
the prosthetic heart valve that extend to one or more tissue anchor
locations within the heart. In one preferred embodiment, the
tethers extend downward through the left ventricle, exiting the
left ventricle at the apex of the heart to be fastened on the
epicardial surface outside of the heart. Similar anchoring is
contemplated herein as it regards the tricuspid, or other valve
structure requiring a prosthetic. There may be from 2 to 8 tethers
which are preferably attached to the stent.
[0105] In another preferred embodiment, the tethers may optionally
be attached to the cuff to provide additional control over
position, adjustment, and compliance. In this preferred embodiment,
one or more tethers are optionally attached to the cuff, in
addition to, or optionally, in place of, the tethers attached to
the stent. By attaching to the cuff and/or the stent, an even
higher degree of control over positioning, adjustment, and
compliance is provided to the operator during deployment.
[0106] During deployment, the operator is able to adjust or
customize the tethers to the correct length for a particular
patient's anatomy. The tethers also allow the operator to tighten
the cuff onto the tissue around the valvular annulus by pulling the
tethers, which creates a leak-free seal.
[0107] In another preferred embodiment, the tethers are optionally
anchored to other tissue locations depending on the particular
application of the prosthetic heart valve. In the case of a mitral
valve, or the tricuspid valve, there are optionally one or more
tethers anchored to one or both papillary muscles, septum, and/or
ventricular wall.
[0108] The tethers, in conjunction with the cuff, provide for a
compliant valve which has heretofore not been available. The
tethers are made from surgical-grade materials such as
biocompatible polymer suture material. Examples of such material
include 2-0 exPFTE (polytetrafluoroethylene) or 2-0 polypropylene.
In one embodiment the tethers are inelastic. It is also
contemplated that one or more of the tethers may optionally be
elastic to provide an even further degree of compliance of the
valve during the cardiac cycle. Upon being drawn to and through the
apex of the heart, the tethers may be fastened by a suitable
mechanism such as tying off to a pledget or similar adjustable
button-type anchoring device to inhibit retraction of the tether
back into the ventricle. It is also contemplated that the tethers
might be bioresorbable/bioabsorbable and thereby provide temporary
fixation until other types of fixation take hold such a biological
fibrous adhesion between the tissues and prosthesis and/or radial
compression from a reduction in the degree of heart chamber
dilation.
[0109] Further, it is contemplated that the prosthetic heart valve
may optionally be deployed with a combination of installation
tethers and permanent tethers, attached to either the stent or
cuff, or both, the installation tethers being removed after the
valve is successfully deployed. It is also contemplated that
combinations of inelastic and elastic tethers may optionally be
used for deployment and to provide structural and positional
compliance of the valve during the cardiac cycle.
Pledget
[0110] In one embodiment, to control the potential tearing of
tissue at the apical entry point of the delivery system, a
circular, semi-circular, or multi-part pledget is employed. The
pledget may be constructed from a semi-rigid material such as PFTE
felt. Prior to puncturing of the apex by the delivery system, the
felt is firmly attached to the heart such that the apex is
centrally located. Secondarily, the delivery system is introduced
through the central area, or orifice as it may be, of the pledget.
Positioned and attached in this manner, the pledget acts to control
any potential tearing at the apex.
Tines/Barbs
[0111] In another embodiment the valve can be seated within the
valvular annulus through the use of tines or barbs. These may be
used in conjunction with, or in place of one or more tethers. The
tines or barbs are located to provide attachment to adjacent
tissue. In one preferred embodiment, the tines are optionally
circumferentially located around the bend/transition area between
the stent and the cuff. Such tines are forced into the annular
tissue by mechanical means such as using a balloon catheter. In one
non-limiting embodiment, the tines may optionally be semi-circular
hooks that upon expansion of the stent body, pierce, rotate into,
and hold annular tissue securely.
Stabilized Tissue or Biocompatible Material
[0112] In one embodiment, it is contemplated that multiple types of
tissue and biocompatible material may be used to cover the cuff, to
form the valve leaflets, to form a wireless leaflet assembly,
and/or to line both the inner and/or outer lateral walls of the
stent. As stated previously, the leaflet component may be
constructed solely from stabilized tissue, without using wire, to
create a leaflet assembly and valve leaflets. In this aspect, the
tissue-only leaflet component may be attached to the stent with or
without the use of the wire form. In a preferred embodiment, there
can be anywhere from 1, 2, 3 or 4 leaflets, or valve cusps.
[0113] It is contemplated that the tissue may be used to cover the
inside of the stent body, the outside of the stent body, and the
top and/or bottom side of the cuff wire form, or any combination
thereof.
[0114] In one preferred embodiment, the tissue used herein is
optionally a biological tissue and may be a chemically stabilized
valve of an animal, such as a pig. In another preferred embodiment,
the biological tissue is used to make leaflets that are sewn or
attached to a metal frame. This tissue is chemically stabilized
pericardial tissue of an animal, such as a cow (bovine pericardium)
or sheep (ovine pericardium) or pig (porcine pericardium) or horse
(equine pericardium).
[0115] Preferably, the tissue is bovine pericardial tissue.
Examples of suitable tissue include that used in the products
Duraguard.RTM., Peri-Guard.RTM., and Vascu-Guard.RTM., all products
currently used in surgical procedures, and which are marketed as
being harvested generally from cattle less than 30 months old.
Other patents and publications disclose the surgical use of
harvested, biocompatible animal thin tissues suitable herein as
biocompatible "jackets" or sleeves for implantable stents,
including for example, U.S. Pat. No. 5,554,185 to Block, U.S. Pat.
No. 7,108,717 to Design & Performance-Cyprus Limited disclosing
a covered stent assembly, U.S. Pat. No. 6,440,164 to Scimed Life
Systems, Inc. disclosing a bioprosthetic valve for implantation,
and U.S. Pat. No. 5,336,616 to LifeCell Corporation discloses
acellular collagen-based tissue matrix for transplantation.
[0116] In one preferred embodiment, the valve leaflets may
optionally be made from a synthetic material such a polyurethane or
polytetrafluoroethylene. Where a thin, durable synthetic material
is contemplated, e.g. for covering the cuff, synthetic polymer
materials such expanded polytetrafluoroethylene or polyester may
optionally be used. Other suitable materials may optionally include
thermoplastic polycarbonate urethane, polyether urethane, segmented
polyether urethane, silicone polyether urethane,
silicone-polycarbonate urethane, and ultra-high molecular weight
polyethylene. Additional biocompatible polymers may optionally
include polyolefins, elastomers, polyethyleneglycols,
polyethersulphones, polysulphones, polyvinylpyrrolidones,
polyvinylchlorides, other fluoropolymers, silicone polyesters,
siloxane polymers and/or oligomers, and/or polylactones, and block
co-polymers using the same.
[0117] In another embodiment, the valve leaflets may optionally
have a surface that has been treated with (or reacted with) an
anti-coagulant, such as, without limitation, immobilized heparin.
Such currently available heparinized polymers are known and
available to a person of ordinary skill in the art.
[0118] Alternatively, the valve leaflets may optionally be made
from pericardial tissue or small intestine submucosal tissue.
[0119] Manufacture of Ultra-Thin Stabilized Tissue
[0120] In a preferred embodiment, ultra-thin vapor-cross linked
stabilized bioprosthetic or implant tissue material is
contemplated. Tissue having a 0.003.degree. (0.0762 mm) to about
0.010'' (0.254 mm) may be made using a process comprising the steps
of: (a) vapor cross-linking a pre-digested compressed tissue
specimen by exposing the tissue specimen to a vapor of a
cross-linking agent selected from the group consisting of
aldehydes, epoxides, isocyanates, carbodiimides, isothiocyanates,
glycidalethers, and acyl azides; and (b) chemically cross-linking
the vapor-cross-linked tissue specimen by exposing the
vapor-crosslinked tissue specimen to an aqueous crosslinking bath
for a predetermined time, such crosslinking bath containing a
liquid phase of a crosslinking agent selected from the group
consisting of aldehydes, epoxides, isocyanates, carbodiimides,
isothiocyanates, glycidalethers, and acyl azides. [para 15] Such
tissue may be porcine, ovine, equine or bovine in origin and
preferably the initial material is taken from a bovine animal 30
days old or less, although tissue from older animals is
contemplated as within the scope of the invention. In one preferred
embodiment, the tissue specimen is subjected to chemical
dehydration/compression and mechanical compression before
cross-linking.
[0121] Pre-digestion is provided by digesting a harvested, cleaned
pericardial tissue in a solution containing a surfactant, such as
1% sodium laurel sulfate. The chemical dehydration/compression step
comprises subjecting the tissue specimen to hyperosmotic salt
solution. And, the mechanical compression may be performed by
subjecting the tissue specimen to a roller apparatus capable of
compressing the tissue specimen to a thickness ranging from about
0.003.degree. (0.0762 mm) to about 0.010'' (0.254 mm).
[0122] The animal collagen tissue specimen is then chemically
cross-linked first by exposing the tissue to formaldehyde vapor for
approximately 10 minutes, and second by immersing the tissue in a
glutaraldehyde solution for two consecutive sessions of
approximately 24 hours each.
Retrieval System
[0123] In another embodiment, a retrieval system is contemplated
for quickly removing the prosthetic valve during an aborted
surgical deployment using minimally invasive cardiac catheter
techniques. In this embodiment, the tethers would be captured by a
catheter having a snare attachment. Once the tethers were captured,
an intra-ventricular funnel attachment would guide the prosthetic
valve into a collapsed, compressed conformation by pulling on the
tethers, thus pulling the compressed prosthetic valve into the
removal catheter for subsequent extraction.
[0124] To better assist understanding of the inventive subject
matter, the following terms are given a more detailed
definition.
DESCRIPTION OF FIGURES
[0125] Referring now to the FIGURES, FIG. 1 shows one embodiment of
a prosthetic heart valve 110 according to the present invention,
comprising tubular stent 112 having tether attachment structures
114 at one end and tubular stent 112 is attached to cuff 116 at the
other end. Leaflet assembly 118 (not shown) is disposed within
stent 112 and supports leaflets 120 (also not shown). Cuff 116 has
independent articulating loops of wire 122 and covering 124.
[0126] As stated, tubular stent 112 may be an expandable laser cut
stent or an expandable braided stent. Tubular stent 112 may be
constructed of Martensitic or super elastic metal alloys. Tubular
stent 112 may be compressed along its longitudinal axis and will
fit into a catheter-based stent delivery system. When the tubular
stent 112 is delivered to the location where it is to be installed,
it is expelled from the catheter by an obturator and deposited at
the site where it is to be deployed.
[0127] Tubular stent 112 includes a plurality of tether attachments
114 upon which a tether (not shown) may be connected. FIG. 1 shows
an embodiment having three tether attachments which are integrated
into the distal portion of the stent 112. Leaflet assembly 118 is a
separate but integrated structure that is disposed within the stent
112. Leaflet assembly 118 functions to provide the structure upon
which the valve leaflets or cusps 120 are located. Leaflet assembly
118 may be made entirely of stabilized tissue or it may be a
combination wire and tissue structure. Where leaflet assembly 118
is composed entirely of tissue, it is contemplated that the leaflet
assembly, leaflet support structure, and leaflets or cusps 120 are
made from tissue. It is contemplated as within the scope of the
invention that different qualities of stabilized tissue, i.e. thin
or thick, structurally rigid or flexible as it may be, may be used
for the different components of the cuff covering 124, the stent
covering, the leaflet assembly 118 and the leaflets 120. Where
leaflet assembly 118 is composed of wire and tissue, it
contemplated that assembly or support(s), or both, may be made from
wire, and the cusps 120 would necessarily be made from tissue.
[0128] Prosthetic heart valve 110 also includes cuff 116. FIG. 1
shows cuff 116 formed from a cuff wire form 122 that is covered by,
in one embodiment, stabilized tissue 124. In one embodiment, the
cuff wire form is an extension of the stent itself, where the stent
has been heated and manipulated upon a form to create the extended
spindles of the flat, collar plate of the cuff. In another
embodiment, the cuff wire form 122 is made separate from the stent
112 and attached as a flat collar plate constructed to include an
inner rim 130 and an outer rim 132, with independent loops of wire
122 that create lobes or segments extending axially around the
circumference of the inner rim, the joint 130 where the cuff 116
meets the tubular stent 112.
[0129] Referring now to FIG. 2, an exploded component view is
provided that shows cuff covering 124 in FIG. 2A. In FIG. 2B, the
wire cuff loops, or spindles, 122, is illustrated along with stent
body 112 and tether attachments 114. The combination of the
stabilized tissue of the cuff covering 124 and wire cuff spindles,
make up a cuff structure and provide a semi-rigid form that assists
in the sealing of the cuff against the atrial trabeculations and
tissue within and adjacent to the mitral annulus. Referring to the
stent body, it is contemplated as within the scope of the invention
to include both laser cut stent technology and/or the braided stent
technology. Where the cuff wire form 122 is merely an extension of
a braided stent and forms a unitary stent-cuff construction, the
spindles are formed by heating a Nitinol.TM. stent on a mold to
create the proper extension and angle necessary to establish the
cuff or collar portion.
[0130] Where the stent is laser cut, the cuff wire form 122 may be
manufactured as a unitary laser-cut stent-cuff construction. In
this embodiment, the cuff wire form and the stent are laser cut
within the same overall manufacturing process. Where the cuff wire
form is made separate from the stent and attached as a flat collar
plate, the cuff wire form and stent may be manufactured/laser cut
separately and attached using laser weld or other similar technique
to create a non-fatiguing elastic stent-cuff joint capable of
maintaining elastic compliance while it is deployed.
[0131] As noted, the rim may consist of an artificial transition
point between the stent and the cuff where the stent has been
heated to change the shape and angle of the topmost portion of the
stent or the valve has been laser cut to create it's overall wire
form, or the rim may consist of a constructed transition point such
as a laser welded joint for attaching two component parts.
[0132] Once the cuff is covered by stabilized tissue 124, the loops
122 provide the cuff 116 the ability to travel or flex up and down,
along the longitudinal axis; longitudinal defined by the lengthwise
axis of the stent. As stated, this flexibility or compliance
provides the prosthetic heart valve, specifically the cuff, upon
being deployed within a patient's heart, the ability to conform to
the anatomical shape of the left atrium, maintain the conforming
shape during the cardiac cycle, and provide a tight seal against
the atrial tissue adjacent the mitral valve aperture. This feature
reduces or removes the guesswork that often accompanies the
pre-surgical sizing of a mitral valve. By providing a better fit,
this necessarily prevents blood from leaking around the implanted
prosthetic heart valve.
[0133] The cuff tissue 126 is thin, durable, and may be attached to
the top, bottom, or both sides of the cuff 116.
[0134] Referring now to FIG. 2C is a stent liner 128 made from
tissue and that may optionally function to support the leaflets of
the valve. This liner is contemplated as being made of tissue or
biocompatible material as disclosed herein. The stent may also
optionally have a inner stent liner and/or an outer (surface) stent
liner. FIG. 2D is a perspective view of one embodiment of a
two-piece structure made of leaflets 120. In this embodiment, the
leaflet structure is illustrated in a prosthetic heart valve having
a mitral valve shape, a "saddle shape" that constitutes a
hyperbolic paraboloid to afford one specific form of structural
integrity.
[0135] Referring now to the exploded view in FIG. 3 A-E, the cuff
covering 124 is shown in FIG. 3A. The stent body 112 and cuff
spindles 122 are shown in FIG. 3B. FIG. 3C shows a stent liner 128
made from tissue and that may optionally function to support the
leaflets of the valve. FIG. 3D is a perspective view of one
embodiment of a two-piece structure made of leaflets 120, and
illustrated in a prosthetic heart valve having a mitral valve
shape, a "saddle shape".
[0136] FIG. 3E shows the use of a structural wire support 126 for
the leaflets 120. This leaflet structural wire support also
provides spring-like tension to assist in the proper orientation of
the leaflets once the prosthetic heart valve is expanded from a
compressed stored shape to its final functional shape. FIG. 3E
shows the three junctions 146 (commissural tips) and the three
arched wires 148 (of this embodiment) of the leaflet structural
wire support 126. Leaflet wire form is preferably constructed as a
single wire that is molded, twisted, and/or manipulated into the
final shape. In another embodiment, the leaflet wire form is series
of wires that have been attached, e.g. laser welded. In one
embodiment, the junctions 146 move independently of the stent.
Specifically, the junction end of the leaflet assembly may not be
attached to the stent, but only the upper portion. Having
unattached junctions with the ability to flex inward and, more
importantly, expand outward, gives the leaflet wire form the
structural ability to collapse when compressed and expand when
deployed. The ability to compress and expand independently of one
another, relieves mechanical stresses on the tissue.
[0137] Referring now to FIG. 4, FIG. 4 shows inner rim 130 and
outer rim 132 of cuff 116. Spindles 122 are shown between the outer
rim 128 and the inner rim 130. Valve leaflets 120 are shown within
the inner rim 130.
[0138] FIG. 5 shows a side view from slightly below the horizontal
plane of one embodiment of a prosthetic valve according to the
present invention to show the bottom surface of the cuff. FIG. 5
shows stent 112 having three tether attachment structures 114
projecting from the distal end of stent 112 for attaching to
tethers 138.
[0139] FIG. 5 shows an example of an embodiment wherein the cuff
116 is formed from the stent 112 by heating and shaping.
[0140] FIG. 6 shows an example of an embodiment wherein the cuff
116 and stent 112 are formed from two joined pieces. FIG. 6 also
shows that tethers 138 are not attached to the leaflet assembly or
leaflet wire form 148 and 146 (shown for illustration purposes but
would not be visible through tissue or synthetic material, e.g.
liner), but rather the tethers 138 are contemplated as attaching to
the stent 112, to the base of the cuff 116, to an upper portion of
the cuff 116, or a combination of the above.
[0141] Referring now to FIG. 7, there is shown an example of where
the cuff spindles may vary in design size and shape. FIG. 7 shows a
completely expanded prosthetic valve 110 fully expelled from the
flexible delivery catheter, including cuff wire form 122, cuff
tissue covering 124, tethers 138, tubular stent 112, tether
attachment 114, and tethers 138. FIG. 7 illustrates where every
other spindle is longer that the adjacent showing an alternating
pattern. This provides an advantage of additional coverage and
compliance of various cuff designs, in combination with how tethers
138 are pulled and shortened to adjust or move the prosthetic valve
towards and within the valvular annulus where it will be seated,
adjusted, and fastened in place to complete the deployment. FIG. 7
also shows that tethers 138 are not attached in this embodiment to
the leaflet assembly or leaflet wire form 148 and 146 (shown for
illustration purposes but would not be visible through tissue or
synthetic material, e.g. liner)
[0142] FIG. 8 shows another variation of one preferred embodiment
of the present invention where the spindles do not alternate, but
rather two spindles on either side create an elongated cuff for a
prosthetic valve where this provides an advantage.
[0143] FIG. 9 shows a top view of a three-leaflet structure 156 as
though from inside the left atrium looking down toward the left
ventricle, and shows the completely expanded prosthetic heart valve
110 seated and adjusted to form a tight seal within the mitral
annulus. FIG. 9 also shows valve leaflets 120, cuff 116, and
independent loops of wire 122.
[0144] Referring now to FIG. 10, there is provided an illustration
of how the cuff and stent body may be formed in such a manner to
create various positions, e.g. angles, for the cuff. The angular
relationship between the cuff 116 and the stent 112 function to
seal the prosthetic heart valve against the mitral valve aperture
and prevent leaking In one embodiment, FIG. 10A, the angle of the
cuff may also include a more acute inverted-funnel shaped angle.
Although not limiting, in one example, the angle is 60 degrees.
FIG. 10B illustrates the angle of an approximately perpendicular
angle. FIG. 10C illustrates a more obtuse funnel-shaped angle, e.g.
150 degrees, in relation to the longitudinal axis of the stent.
[0145] FIG. 11 shows how tines or barbs can facilitate the
attachment to the tissue, such as the mitral annulus or the
tricuspid, annulus. FIG. 11 shows cuff 116 attached to stent body
112 where barbs 158 have been attached at the neck of the
prosthetic valve where the cuff meets or transitions to the stent
body.
[0146] FIG. 12 A-B illustrates a specific form of hooked barb 158
where the hooked barb is adjusted to provide an opening between the
barb and the stent body where an operator would direct the annular
tissue to assist with seating the valve. Upon placing the
prosthetic valve 110 there, a balloon catheter or other expansion
means is inserted into the stent 112 to expand the internal
diameter, thus causing the hooked barbs 158 to rotate back inwards
toward the stent 112, thus capturing and locking the annular tissue
to the stent body.
[0147] FIG. 13 shows a prosthetic valve according to the present
invention showing tethers 160 attached to the cuff portion 116 with
optional cuff-tether attachments 162 in addition to attachment 114
of the tethers 138 on the stent body. By providing the surgeon the
ability to control, adjust, tighten, the cuff geometry relative to
the stent geometry, many options are provided that were not
heretofore known to be available in the prior art.
[0148] Referring now to FIG. 14, this is a drawing of one preferred
embodiment of equipment as claimed herein that is used to compress
the prosthetic valve and insert the prosthetic valve into the
heart. FIG. 14 shows funnel compressor 142, introducer 144, snare
150, flexible deployment catheter 134, catheter insert 152, and
obturator 136, the implementation of which is further described in
FIG. 15.
[0149] Referring now to FIGS. 15A-F is a series of drawings of one
embodiment of the assembly of a delivery system for a prosthetic
valve according to the present invention. FIGS. 15A-F show the
preparation of the prosthetic valve for implantation into the heart
by showing how the prosthetic valve is loaded into the flexible
delivery catheter. FIG. 15A shows the initial step of attaching the
introducer 144 to the compression funnel 142. FIG. 15B shows the
snare 150 pulling tethers 138 into compression funnel 142 and
threading through introducer 144. FIG. 15C shows the prosthetic
valve 110 just prior to being drawn into the compression funnel 142
as it is pulled rearward using tethers 138 into the introducer 144.
FIG. 15D shows the prosthetic valve 110 (not shown) inserted into
the introducer 144 with the anchoring tethers 138 extending from
the rear of the introducer 144. FIGS. 15 E and 15F show the
flexible delivery catheter 132 being attached to the introducer 144
to introduce, or insert, the compressed prosthetic valve 110 (not
shown) into the flexible delivery catheter 132. In summary, FIG. 15
shows prosthetic valve 110 with tethers 138 that have been
threaded, using a snare 150, through the funnel compressor 142
which is attached to introducer 144. Upon pulling the tethers 138,
the prosthetic valve 110 is mechanically compressed by the funnel
142 and inserted into the introducer 144. The introducer 144 is
then inserted into the delivery catheter 132 in preparation for
loading the delivery catheter. The obturator 136, having diameter
slightly less than the introducer and the delivery catheter, is
then inserted into the rear portion of the introducer and to pushes
the compressed and tethered prosthetic valve into the delivery
catheter. It is contemplated that this process will be performed in
the operating room just prior to installing the valve in the
patient. In another embodiment, a ready-made pre-filled
catheter/valve delivery system is provided.
[0150] Referring now to FIG. 16 is a detailed sectional view of the
catheter delivery system 132, which includes the compressed
prosthetic valve 110 according to the present invention disposed
within the delivery catheter 134. FIG. 16 shows prosthetic valve
110 having cuff 116 attached to stent 112, which further has
tethers 138 leading away from the compressed valve 110.
[0151] FIG. 17 is a cut-away view of a heart with a delivery
catheter containing a prosthetic heart valve according to the
present invention and accessing the heart using an apical approach.
It is contemplated that other surgical approaches to the heart, and
valves in addition to the mitral valve, are within the scope of the
inventive subject matter claimed herein. FIG. 17 shows the delivery
catheter 134 advanced to through the mitral valve and into the left
atrium for deployment of the prosthetic valve 110.
[0152] FIG. 18 A-D is a series of drawings of the deployment of one
embodiment of a prosthetic valve according to the present
invention. FIG. 18 A-D is a series of views of the tip of one
embodiment of a delivery catheter according to the present
invention containing a pre-loaded prosthetic valve which is being
pushed out of the delivery catheter, i.e. by an obturator, starting
with (A) the valve completely within the catheter, (B) the cuff
portion being in view, (C) the stent body following, and (D) the
prosthetic valve with attached tethers for positioning and/or
adjustment and/or securing the valve to tissue. FIGS. 18A-D shows
how the prosthetic valve 110 is deployed from flexible deployment
catheter 134. FIG. 18B shows the cuff 116 emerging from the
catheter 134. FIG. 18C shows the cuff 116 and stent 112 partially
expelled from the delivery catheter 134. FIG. 18D shows the
prosthetic valve completely expelled from the delivery catheter 134
with tethers 138 attached to the stent body and trailing behind
into the catheter. FIG. 18D further shows tethers 138 attached to
the stent 112, with prosthetic valve 110 now expanded and delivered
(but not positioned or adjusted), as the delivery catheter 134 is
withdrawn away from the target location, e.g. atrium.
[0153] Referring now to FIG. 19, FIG. 19 shows a depiction of a
fully deployed prosthetic heart valve 110 installed in the left
mitral valve of the heart having the tethers 138 attached to the
left ventricle apex of the heart. Tethers 138 in this embodiment
extend through the heart muscle and are attached to securing device
140, here shown as a pledget placed on the epicardial surface and
having tethers fastened thereto.
[0154] In this embodiment, the pledget 140 performs the function of
an anchor to which the tethers 138 are attached. Tethers 138 are
strung through the left ventricle apex and pulled downward to seat
prosthetic valve 110 in the atrial valve area. The completely
installed prosthetic valve is held in the left atrium by the cuff
116 and secured to the apex of the heart by tethers 138. The
tethers may be held in place by a securing device which in this
aspect of the invention is a pledget 140 that the tethers are
threaded through and secured against, i.e. by tying a knot or using
a cinching feature.
[0155] Referring now to FIG. 20 is a detailed cross-sectional view
(of the heart) of one embodiment of a prosthetic heart valve
according to the present invention deployed within the mitral valve
aperture of the heart and anchored, in an alternative embodiment,
between (A) where it is seated or lodged by the atrial cuff and (B)
the ventricular tethers connected to papillary muscles 166 and/or
ventricular wall and/or tether(s) attached to septum 164, which are
each secured by one or more securing tissue anchors, anchoring
devices, or anchoring methods.
[0156] FIG. 21A-B shows how the tethers 138 are tied off at the
apex of the heart after deployment of the prosthetic valve 110.
FIG. 21A shows the flexible delivery catheter 134 inserted into the
left ventricular apex along with a suture 156 having partially
installed apical-closure/tissue-buttressing material 158. FIG. 21B
shows the anchoring system of the prosthetic valve in which the
ventricular tethers 138 are shown treaded through the left
ventricle apex and through a partially installed pledget 140; also
shown are fully installed apical suture-closure material 156/158.
Tissue buttressing material may optionally be in one embodiment a
pledget felt.
[0157] Referring now to FIGS. 22 A-B, FIGS. 22 A-B is a pair of
drawings of the lateral deployment of one embodiment of a
prosthetic valve according to the present invention and shows a
prosthetic valve delivery catheter that has accessed the left
atrium via the left ventricle by way of a lateral trans-ventricular
wall approach through the lateral wall of the left ventricle of the
heart. FIGS. 22 A-B show a prosthetic valve delivery catheter that
(A) has accessed the left atrium via the left ventricle by way of a
lateral trans-ventricular wall approach through the lateral wall of
the left ventricle of the heart, to bedeposited the prosthetic
valve into the left atrium, which will be withdrawn the delivery
catheter for adjustment of the tethers, and (B) that has the valve
adjusted and deployed within the mitral annulus.
[0158] FIG. 22B is an illustration of the prosthetic heart valve
110 seated within the mitral annulus and, in this embodiment,
having papillary muscle tethers 166 within the left ventricle. FIG.
22B also shows annulus barbs 158, here shown optionally at both the
transition point from the stent to the cuff 158 and elsewhere on
the cuff itself 168.
[0159] FIG. 23 is a cut-away view of a heart with a delivery
catheter containing a prosthetic heart valve according to the
present invention and accessing the right ventricle of the heart
using an apical approach. FIG. 23 shows the delivery catheter
advanced through to the tricuspid valve and into the right atrium
for deployment of the prosthetic heart valve.
[0160] Referring now to FIGS. 24 A-B that show an embodiment of a
prosthetic valve 110 having a ring or halo feature 154. FIG. 24A is
a bottom view from slightly above the horizontal plane of one
embodiment of a prosthetic valve according to the present invention
to show the bottom surface of the cuff 116 and the halo feature
154. FIG. 24B is a top view from slightly above the horizontal
plane of one embodiment of a prosthetic valve according to the
present invention to show the top surface of the cuff 116.
[0161] FIGS. 24 A-B show an embodiment of a prosthetic valve having
a ring or halo feature 154 attached to the junctions 146 of the
arched wires 148 of leaflet assembly 118.
[0162] The references recited herein are incorporated herein in
their entirety, particularly as they relate to teaching the level
of ordinary skill in this art and for any disclosure necessary for
the commoner understanding of the subject matter of the claimed
invention. It will be clear to a person of ordinary skill in the
art that the above embodiments may be altered or that insubstantial
changes may be made without departing from the scope of the
invention. Accordingly, the scope of the invention is determined by
the scope of the following claims and their equitable
Equivalents.
* * * * *