U.S. patent application number 12/309680 was filed with the patent office on 2009-12-10 for percutaneous valve prosthesis and system and method for implanting same.
This patent application is currently assigned to CARDIAQ VALVE TECHNOLOGIES, INC.. Invention is credited to Arshad Quadri.
Application Number | 20090306768 12/309680 |
Document ID | / |
Family ID | 38982087 |
Filed Date | 2009-12-10 |
United States Patent
Application |
20090306768 |
Kind Code |
A1 |
Quadri; Arshad |
December 10, 2009 |
PERCUTANEOUS VALVE PROSTHESIS AND SYSTEM AND METHOD FOR IMPLANTING
SAME
Abstract
A heart valve prosthesis includes a cylindrical valve cage stent
constructed to be implanted percutaneously in the planar axis of a
native valve annulus, an elastic and compressible, multi-leaflet
valve insertable percutaneously into the body, and an attachment
mechanism for attaching the valve to the superior rim of the valve
cage stent. The valve can be of a bi-leaflet or a tri-leaflet type
and includes a valve frame made from a memory metal and a tissue
cover attached to the valve frame. The valve cage stent is
self-expanding or balloon expandable, made respectively from memory
metal or stainless steel but otherwise structurally the same.
Inventors: |
Quadri; Arshad; (West
Hartford, CT) |
Correspondence
Address: |
JACOBSON HOLMAN PLLC
400 SEVENTH STREET N.W., SUITE 600
WASHINGTON
DC
20004
US
|
Assignee: |
CARDIAQ VALVE TECHNOLOGIES,
INC.
|
Family ID: |
38982087 |
Appl. No.: |
12/309680 |
Filed: |
July 27, 2007 |
PCT Filed: |
July 27, 2007 |
PCT NO: |
PCT/US2007/016855 |
371 Date: |
August 20, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60833791 |
Jul 28, 2006 |
|
|
|
Current U.S.
Class: |
623/1.26 |
Current CPC
Class: |
A61F 2/2418 20130101;
A61F 2/2436 20130101; A61F 2220/0016 20130101; A61F 2/2439
20130101; A61F 2230/0054 20130101; A61F 2250/006 20130101 |
Class at
Publication: |
623/1.26 |
International
Class: |
A61F 2/06 20060101
A61F002/06 |
Claims
1. A heart valve prosthesis comprising: an expandable and
compressible, cylindrical valve cage stent constructed to be
implanted endovascularly in the planar axis of a native valve
annulus, the valve cage stent having a superior rim; an elastic and
compressible, multi-leaflet valve insertable endovascularly into
the body, the valve including an expandable and compressible valve
frame and a tissue cover attached to the valve frame; and
attachment means for attaching the valve to the superior rim of the
valve cage.
2. The heart valve prosthesis of claim 1, wherein the valve frame
is made from a memory metal.
3. The heart valve prosthesis of claim 1, wherein: the valve cage
stent has a fabric covering on the interior surfaces thereof and on
parts of the exterior surfaces thereof to provide a complete seal
and prevent leakage of blood when the valve cage stent is expanded;
and the valve cage stent has first, second, and third zones along
its longitudinal axis, the first zone being between the second and
third zones, the first zone being configured to connect the valve
cage stent to the native valve annulus, the second zone being
configured as the superior valve rim, and the third zone being
configured as an inferior valve skirt for providing additional
support and as an attachment area for the fabric covering and
surrounding tissue to minimize leaking.
4. The heart valve prosthesis of claim 1, wherein the valve is a
bi-leaflet valve, the frame has two substantially semicircular,
expandable, and compressible parts, and the tissue cover is
configured to cover the two parts of the frame with the straight
sides of the two parts in spaced-apart relation.
5. The heart valve prosthesis of claim 4, wherein the tissue cover
has a central aperture and the two parts of the frame have
respective slots, and wherein the heart valve prosthesis further
comprises a deformable hinge having oppositely extending arms
extending through the slots and a stem received through the
aperture, and wherein the attachment means comprises a valve mount
affixed to the superior rim of the valve cage stent and a mating
part on the hinge receivable in the valve mount.
6. The heart valve prosthesis of claim 5, wherein the oppositely
extending arms of the hinge have stops at the ends thereof for
limiting movement of the leaflets.
7. The heart valve prosthesis of claim 5, wherein the mating part
on the hinge is removable from the valve mount, whereby the valve
is replaceable.
8. The heart valve prosthesis of claim 1, wherein the valve is a
tri-leaflet valve, the frame is cylindrical and has three
commissural posts mounted thereon, the tissue cover has three cusps
fitted and sewn to the valve frames, the commissural posts being
sized to maintain the commissural height of the cusps.
9. The heart valve prosthesis of claim 8, wherein the valve cage
stent has three commissural pins extending from the superior rim
thereof, wherein the commissural posts of the frame are cannulated
to receive the commissural pins of the valve cage stent, and
wherein the commissural pins and the commissural posts define the
attachment means.
10. The heart valve prosthesis of claim 8, wherein the tissue cover
comprises fabric and three substantially identical aortic cusps
affixed to the fabric.
11. A method for implanting the percutaneous valve prostheses of
claim 1 in a body, comprising the steps of: endovascularly
inserting the valve cage stent in the planar axis of a native valve
annulus; and endovascularly attaching the valve to the superior rim
of the valve cage stent so that the valve is in a supra annular
position.
12. The method of claim 11, wherein the valve cage stent and the
valve are inserted using respective catheters, and wherein the
valve is attached to the valve cage stent after they are discharged
from their respective catheters.
13. The method of claim 11, wherein the valve cage stent and the
valve are inserted using the same catheter, and the valve is
attached to the valve cage stent within the catheter.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present patent application is based on, and claims
priority from, U.S. provisional Application No. 60/833,791, filed
Jul. 28, 2006, which is incorporated herein by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to heart valve prostheses,
preferably to aortic valve prostheses. More specifically, the
invention relates to heart valve prostheses that can be implanted
percutaneously by means of a catheter from a remote Location
without opening the chest cavity.
[0004] 2. Related Art
[0005] Heart valve surgery is used to repair or replace diseased
heart valves. Valve surgery is an open-heart procedure conducted
under general anesthesia. An incision is made through the patient's
sternum (sternotomy), and the patient's heart is stopped while
blood flow is rerouted through a heart-lung bypass machine.
[0006] Valve replacement may be indicated when there is a narrowing
of the native heart valve, commonly referred to as stenosis, or
when the native valve leaks or regurgitates. When replacing the
valve, the native valve is excised and replaced with either a
biologic or a mechanical valve. Mechanical valves require lifelong
anticoagulant medication to prevent clot formation around the
valve, which can lead to thromboembolic complications and
catastrophic valve failure. Biologic tissue valves typically do not
require such medication. Tissue valves can be obtained from
cadavers (homografts) or can be from pigs (porcine valve) and cows
(bovine pericardial valves). Recently equine pericardium has also
been used for making valves. These valves are designed to be
attached to the patient using a standard surgical technique.
[0007] Valve replacement surgery is a highly invasive operation
with significant concomitant risk. Risks include bleeding,
infection, stroke, heart attack, arrhythmia, renal failure, and
adverse reactions to the anesthesia medications, as well as sudden
death. Two to five percent of patients die during surgery.
[0008] Post-surgery, patients temporarily may be confused due to
emboli and other factors associated with the heart-lung machine.
The first two to three days following surgery are spent in an
intensive care unit where heart functions can be closely monitored.
The average hospital stay is between one and two weeks, with
several more weeks to months required for complete recovery.
[0009] In recent years, advancements in minimally invasive,
endoaortic, surgery interventional cardiology, and intervention
radiology have encouraged some investigators to pursue percutaneous
replacement of the aortic heart valve. Percutaneous Valve
Technologies ("PVT") of Fort Lee, N. J., has developed a
balloon-expandable stent integrated with a bioprosthetic valve,
which is the subject of U.S. Pat. Nos. 5,411,552, 5,840,081,
6,168,614, and 6,582,462 to Anderson et al. The stent/valve device
is deployed across the native diseased valve to permanently hold
the valve open, thereby alleviating a need to excise the native
valve and to position the bioprosthetic valve in place of the
native valve. PVT's device is designed for delivery in a cardiac
catheterization laboratory under local anesthesia using
fluoroscopic guidance, thereby avoiding general anesthesia and
open-heart surgery. The device was first implanted in a patient in
April of 2002.
[0010] PVT's device suffers from several drawbacks. Deployment of
PVT's stent has several drawbacks, including that there is very
little control over its deployment. This lack of control can
endanger the coronary ostea above the aortic valve and the anterior
leaflet of the mitral valve below the aortic valve.
[0011] Another drawback of the PVT device is its relatively large
cross-sectional delivery profile. This is largely due to
fabricating the tri-leaflet pericardial valve inside a robust
stainless steel stent. Considering they have to be durable, the
materials for the valve and the stent are very bulky, thus
increasing the profile of the device. The PVT system's stent/valve
combination is mounted onto a delivery balloon, making retrograde
delivery through the aorta challenging. An antegrade transseptal
approach may therefore be needed, requiring puncture of the septum
and routing through the mitral valve, which significantly increases
complexity and risk of the procedure. Very few cardiologists are
currently trained in performing a transseptal puncture, which is a
challenging procedure by itself.
[0012] Another drawback of the PVT device is its lack of fixation
provision. It in effect uses its radial force to hold the stent in
the desired position. For this to work, sufficient dilatation of
the valve area has to be achieved; but this amount of dilation can
cause damage to the annulus. Also, due to its inability to have an
active fixation mechanism, the PVT device cannot be used to treat
aortic regurgitation.
[0013] Another drawback to this system is that it does not address
the leakage of blood around the implant, after its
implantation.
[0014] Other prior art replacement heart valves use self-expanding
stents that incorporate a valve. One such device is that disclosed
in U.S. Pat. No. 7,018,406 to Seguin et al. and assigned to and
made by CoreValve SA. In the endovascular aortic valve replacement
procedure, accurate placement of aortic valves relative to coronary
ostia and the mitral valve is critical. Standard self-expanding
systems have very poor accuracy in deployment, however. Often the
proximal end of the stent is not released from the delivery system
until accurate placement is verified by fluoroscopy and the stent
typically jumps once released. It is therefore often impossible to
know where the ends of the stent will be with respect to the native
valve, the coronary ostia, and the mitral valve. The anchoring
mechanism is not actively provided (that is, there is no method of
fixation other than the use of radial force and barbs that project
into the surrounding tissue and not used as positioning marker
(that is, markers seen under fluoroscopy to determine the position
of the device).
[0015] A simple barb as used in the CoreValve device relies mainly
on friction for holding the position.
[0016] Another drawback of prior art self-expanding replacement
heart valve systems is their lack of radial strength. In order for
self-expanding systems to be easily delivered through a delivery
sheath, the metal needs to flex and bend inside the delivery
catheter without being plastically deformed. In arterial stents,
this is not a challenge, and there are many commercial arterial
stent systems that apply adequate radial force against the vessel
wall and yet can collapse to a small enough of a diameter to fit
inside a delivery catheter without plastically deforming. However,
when the stent has a valve fastened inside it, as is the case in
aortic valve replacement, the anchoring of the stent to vessel
walls is significantly challenged during diastole. The force
required to hold back arterial pressure and prevent blood from
going back inside the ventricle during diastole will be directly
transferred to the stent/vessel wall interface. Therefore the
amount of radial force required to keep the self expanding
stent/valve in contact with the vessel wall and prevent it from
sliding will be much higher than in stents that do not have valves
inside of them. Moreover, a self-expanding stent without sufficient
radial force will end up dilating and contracting with each
heartbeat, thereby distorting the valve, affecting its function and
resulting in dynamic repositioning of the stent during delivery.
Stent foreshortening or migration during expansion may lead to
improper alignment.
[0017] Additionally, the stent disclosed in U.S. Pat. No. 6,425,916
to Garrison simply crushes the native valve leaflets against the
heart wall and does not engage the leaflets in a manner that would
provide positive registration of the device relative to the native
position of the valve. This increases an immediate risk of blocking
the coronary ostia, as well as a longer-term risk of migration of
the device post-implantation. Further still, the stent comprises
openings or gaps in which the replacement valve is seated
post-delivery. Tissue may protrude through these gaps, thereby
increasing a risk of improper seating of the valve within the
stent.
[0018] In view of drawbacks associated with previously known
techniques for endovascularly replacing a heart valve, it would be
desirable to provide methods and apparatus that overcome those
drawbacks.
[0019] Sadra et al. (U.S. published application No. 20050137701)
describes a mechanism for anchoring a heart valve, the anchoring
mechanism having an actuation system operated remotely. This
mechanism addresses the fixation issue; however, considering the
irregular shape of the aortic annulus there is a real potential for
deforming the prosthetic valve annulus; this may require additional
balloon angioplasty to give it its final shape, and also make the
new valve more prone to fatigue and fracture. Moreover if full
expansion of the stent is prone to deformation, the leaflet
coaptation of the valve will be jeopardized.
[0020] Sadra et al (U.S. published application No. 20050137691)
describes a system with two pieces, a valve piece and an anchor
piece. The valve piece connects to the anchor piece in such a
fashion that it will reduce the effective valve area considerably.
Valve area, i.e., the inner diameter of the channel after the valve
leaflets open, is of prime importance when considering an aortic
valve replacement in a stenotic valve. Garrison's valve is also
implanted in the inner portion of the stent, compromising the
effective valve outflow area. Sadra et al's and Garrison's valves
overlook this very critically important requirement.
[0021] The technologies described above and other technologies (for
example, those disclosed in U.S. Pat. No. 4,908,028 to Colon et
al.; U.S. Published Application No. 2003/0014104, U.S. Published
Application No. 2003/0109924, U.S. Published Application No.
2005/0251251, U.S. Published Application No. 2005/0203616, and U.S.
Pat. No. 6,908,481 to Cribier; U.S. Pat. No. 5,607,469 to Frey;
U.S. Pat. No. 6,723,123 to Kazatchkov et al.; Germany Patent No. DE
3,128,704 A1 to Kuepper; U.S. Pat. No. 3,312,237 to Mon et a).;
U.S. Published Application No. 2005/0182483 to Osbourne et al.;
U.S. Pat. No. 1,306,391 to Romanoff; U.S. Published Application No.
2005/0203618 to Sharkcawy et al.; U.S. Published Application No.
2006/0052802 to Sterman et al.; U.S. Pat. No. 5,713,952; and U.S.
Pat. No. 5,876,437 to Vanney et al.) also use various biological,
or other synthetic materials for fabrication of the prosthetic
valve. The duration of function and physical deterioration of these
new valves have not been addressed. Their changeability has not
been addressed, in the percutaneous situation.
[0022] It is to the solution of these and other problems that the
present invention is directed.
SUMMARY OF THE INVENTION
[0023] It is accordingly a primary object of the present invention
to provide to methods and apparatus for endovascularly replacing a
heart valve.
[0024] In is another object of the present invention to provide
methods and apparatus for endovascularly replacing a heart valve
with a replacement valve prosthesis using a balloon expandable
and/or self expanding valve cage stent upon which a bi-leaflet or
tri-leaflet elastic valve is inserted.
[0025] It is also a feature of this invention that the valve piece
of the implant is removable, and thus exchangeable, in the event of
long or medium term failure of the implanted valve.
[0026] It is another object of this invention to provide maximal
valve area to the out flow tract of the left ventricle, thus
minimizing the gradient across the valve, by using a supra annular
implant of the valve piece to the valve cage stent.
[0027] These and other objects are achieved by a heart valve
prosthesis comprising a cylindrical valve cage stent constructed to
be implanted percutaneously in the planar axis of a native valve
annulus, the valve cage stent having a superior rim; and an elastic
and compressible, multi-leaflet valve insertable percutaneously
into the body, the valve including a valve frame made from a memory
metal and a tissue cover attached to the valve frame; and
attachment means for attaching the valve to the superior rim of the
valve cage.
[0028] The valve can be a bi-leaflet or a tri-leaflet valve. The
bi-leaflet valve includes a frame, a tissue cover, a deformable
hinge, and means for detachably connecting the valve to the valve
cage stent. The frame has two substantially semicircular,
expandable, and compressible parts, and the tissue cover is
configured to cover the two parts of the frame with the straight
sides of the two parts in spaced-apart relation. The tissue cover
has a central aperture and the two parts of the frame have
respective slots. The deformable hinge has oppositely extending
arms extending through the slots and a stem received through the
aperture. The superior rim of the valve cage stent has a valve
mount affixed thereto for receiving a mating part on the hinge,
thereby defining the attachment means.
[0029] The tri-leaflet valve includes a frame, a tissue cover, and
means for detachably connecting the valve to the valve cage stent.
The frame is cylindrical and has three commissural posts mounted
thereon. The tissue cover has three cusps fitted and sewn to the
valve frame, the commissural posts being sized to maintain the
commissural height of the cusps. The valve cage stent has three
commissural pins extending from the superior rim thereof, and the
commissural posts of the frame are cannulated to receive the
commissural pins of the valve cage stent, thereby defining the
attachment means.
[0030] Other objects, features and advantages of the present
invention will be apparent to those skilled in the art upon a
reading of this specification including the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The invention is better understood by reading the following
Detailed Description of the Preferred Embodiments with reference to
the accompanying drawing figures, in which like reference numerals
refer to like elements throughout, and in which:
[0032] FIG. 1 is a diagram of a valve prosthesis in accordance with
the present invention.
[0033] FIG. 2A is a diagrammatic plan view of a frame for a
bi-leaflet percutaneous heart valve in accordance with the present
invention.
[0034] FIG. 2B is a diagrammatic plan view of a tissue cover for
the frame of FIG. 2A.
[0035] FIG. 2C is a diagrammatic plan view of an assembled
bi-leaflet percutaneous heart valve in accordance with the present
invention, incorporating the frame of FIG. 2A and the tissue cover
of FIG. 2B.
[0036] FIG. 2D is a diagrammatic side elevational view of the
bi-leaflet percutaneous heart valve of FIG. 2C in the open
position.
[0037] FIG. 2E is a diagrammatic side elevational view of the
bi-leaflet percutaneous heart valve of FIG. 2C in the closed
position.
[0038] FIG. 2F is a top perspective view of an assembled bi-leaflet
percutaneous heart valve in accordance with the present invention,
in the closed position.
[0039] FIGS. 2G and 2H are top and side perspective views of the
bi-leaflet percutaneous heart valve of FIG. 2F in the open
position.
[0040] FIGS. 2I and 2J are side perspective views of the valve cage
stent for use with the bi-leaflet percutaneous heart valve of FIG.
2F.
[0041] FIG. 2K is a partial perspective view of the bi-leaflet
percutaneous heart valve of FIG. 2F mounted on the valve cage stent
of FIG. 2I, with the valve in the closed position.
[0042] FIG. 2L is a partial perspective view of the bi-leaflet
percutaneous heart valve of FIG. 2F mounted on he valve cage stent
of FIG. 2I, with the valve in the open position.
[0043] FIG. 3A is a diagrammatic perspective view of a frame for a
tri-leaflet percutaneous heart valve in accordance with the present
invention.
[0044] FIG. 3B is a perspective view of a tissue cover for the
frame of FIG. 3A.
[0045] FIG. 3C is a perspective view of an assembled tri-leaflet
percutaneous heart valve in accordance with the present invention,
incorporating the frame of FIG. 3A and the tissue cover of FIG.
3B
[0046] FIG. 3D is a side perspective view of the valve cage stent
for use with the tri-leaflet percutaneous heart valve of FIG.
3C.
[0047] FIGS. 3E and 3F are top perspective views of the valve cage
stent for use with the tri-leaflet percutaneous heart valve of FIG.
3C.
[0048] FIG. 3G is a diagrammatic view of a portion the valve cage
stent for use with the tri-leaflet percutaneous heart valve of FIG.
3C, which as been opened up and flattened for purposes of
illustration.
[0049] FIG. 3H is a partially cut-away perspective view of the
tri-leaflet percutaneous heart valve of FIG. 3C mounted on the
valve cage stent of FIG. 3D, in the undeployed condition.
[0050] FIG. 3I is a partially cut-away perspective view of the
tri-leaflet percutaneous heart valve of FIG. 3C mounted on the
valve cage stent of FIG. 3D, in the deployed condition.
[0051] FIGS. 4A-4G show the sequence of steps in implantation of
the bi-leaflet percutaneous heart valve prosthesis of FIG. 2C in an
aorta, in which the valve is attached to the valve cage stent
outside the delivery catheter.
[0052] FIGS. 5A-5I are diagrammatic representations of the sequence
of steps in implantation of the bi-leaflet percutaneous heart valve
of FIG. 2C, the aorta being omitted from all of FIGS. 5A-5I and the
valve cage being omitted from FIGS. 5A-5F for clarity.
[0053] FIGS. 6A-6J show the sequence of steps in implantation of
the tri-leaflet percutaneous heart valve of FIG. 3C in an aorta, in
which the valve is attached to the valve cage stent outside the
delivery catheter.
[0054] FIGS. 7A and 7B are exploded and assembled views,
respectively, of the delivery system apparatus used in implantation
of the bi-leaflet and tri-leaflet valves in accordance with the
present invention.
[0055] FIG. 7C is an end view of the flexible sheath of the
delivery system apparatus of FIGS. 7A and 7B.
[0056] FIG. 8 is a side view of a valve cage stent mounted on a
balloon catheter.
[0057] FIGS. 9A-9T show the sequence of steps in implantation of
the tri-leaflet percutaneous heart valve of FIG. 3C in an aorta, in
which the valve is attached to the valve cage stent within the
delivery catheter.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0058] In describing preferred embodiments of the present invention
illustrated in the drawings, specific terminology is employed for
the sake of clarity. However, the invention is not intended to be
limited to the specific terminology so selected, and it is to be
understood that each specific element includes all technical
equivalents that operate in a similar manner to accomplish a
similar purpose.
[0059] The present invention relates to heart valve prostheses that
can be implanted percutaneously by means of a catheter from a
remote location without opening the chest cavity. As shown in FIG.
1, the valve prosthesis 10 comprises two parts, (1) a valve cage
stent 20 constructed to be implanted in the planar axis of the
native valve annulus, (2) an elastic and compressible valve 30, and
(3) an attachment mechanism for attaching the valve 30 to the
superior rim of the above mentioned valve cage stent 20. In
accordance with the present invention, two types 110 and 210 of
heart valve prosthesis 10 are contemplated, one type 110
incorporating an elastic and compressible bi-leaflet hinged valve
130 (shown in FIGS. 2A-2E) and the other type 210 incorporating an
elastic and compressible tri-leaflet biologic valve 230 (shown in
FIGS. 3A-3C). A system and method for implanting the valves (shown
in FIGS. 4A-4G, 5A-5I, and 6A-6J) is also encompassed by the
invention.
[0060] Referring now to FIGS. 2A-2H, the bi-leaflet tissue valve
130 comprises a two-part (that is, a two-leaflet) frame 132 made
from a memory metal wire or strip and a tissue cover 133. As best
shown in FIG. 2A, each part 132a and 132b of the frame 132 is
substantially semicircular. Portions of each part 132a and 132b of
the frame 132 (for example, the straight side and the center
portion of the curved side) are configured (for example, by having
a sinusoidal configuration, shown by broken lines in FIGS. 2A and
2C) so that each part 132a and 132b of the frame 132, as well as
the frame 132 as a whole, is expandable and compressible, while the
remaining portions of the frame 132 are not expandable and
compressible.
[0061] Each part 132a and 132b of the frame 132 includes a slot 134
for receiving a hinge 135 having a shape when deployed that is
similar to a lower-case "t", as shown in FIGS. 2D and 2E, having
two aims 135a and 135b and a stem 135c. The slot 134 is formed
unitarily with the frame 132. The "t"-shaped hinge 135 is stamped
out of memory metal (for example, nitinol) sheeting so that it is
deformable. The arms 135 and 135b of the hinge 135 have projections
135d at their ends, which function as stops for the leaflets. The
stem 135c of the hinge 135 has a snap-on or screw-in mechanism 141
for attachment to a valve mount 142 (shown in FIGS. 2I-2L), as
described below.
[0062] The tissue cover 133 (shown in FIG. 2B) is made, for
example, of equine or bovine pericardium, or various synthetic
materials, for example, or medical grade silicone, fabric, or other
compressible, materials, and is configured to cover the two parts
132a and 132b of the frame 132 with their straight sides in spaced
apart relation, with a central aperture 133a in the center for
receiving the stem of the "t"-shaped hinge 135 and two side
apertures 133b in alignment with the slots 134 for receiving the
arms 135a and 135b of the hinge 135. The tissue cover 133 is sewn
to each part 132a and 132b of the frame 132, as shown in FIGS. 2C
and 2F-2H, and thus connects the two parts 132a and 132b of the
frame 132 in spaced-apart relation.
[0063] As discussed in greater detail below, in use, the bi-leaflet
valve 130 is detachably connected to a valve mount 142 (shown in
FIGS. 2I and 21) via the "t"-shaped hinge 135, as shown in FIGS.
2K-2N, 4D-4G, and 5G-5I. The valve mount 142 is also made from a
memory metal so that it is collapsible. More specifically, the
valve mount 142 has arms 142a and 142b on either side of a
receptacle 142c, which are folded up vertically when the valve cage
stent 120 is in its compressed (undeployed) condition, the ends of
the arms 142a and 142b being affixed to the valve cage stent
120.
[0064] The detachable and collapsible bi-leaflet construction of
the valve 130 enables the valve 130 in conjunction with its entire
delivery system to be sized down so that it can be inserted
percutaneously using a catheter, as described below.
[0065] Referring now to FIGS. 3A-3C, the tri-leaflet tissue valve
230 comprises an expandable and compressible valve frame 232 (shown
in FIG. 3A) made from a memory metal wire or strip and a tissue
cover 233 (shown in FIG. 3B and 3C). The tissue cover 233 is made
from the individual cusps of a porcine aortic valve sewn to
appropriate fabric. Three identical cusps are selected. Two or more
pigs are used to get ideal sized aortic cusps. The muscle bar cusp
is preferably not used; and all of the sinus and surrounding tissue
is S discarded. The commissural height is maintained at all cost.
The tissue cover 233 (that is, the cusps sewn to the fabric) is
fitted and sewn to the valve frame 232. The valve frame 232 has
three cannulated commissural posts 240a, 240b, and 240c mounted
thereon, and the tissue cover 233 is sewn to the commissural posts
240a, 240b, and 240c to complete the tri-leaflet valve 230 (FIG.
3C).
[0066] As shown in FIGS. 3A-3C, the tri-leaflet valve 230 is
mounted on commissural pins 240aa, 240bb, and 240cc provided on a
valve cage stent 220 of the type disclosed in provisional
application No. 60/735,221, Attorney Docket P70721US0, which is
incorporated herein by reference in its entirety. More
specifically, the commissural posts 240a, 240b, and 240c of the
valve frame 232 are cannulated to receive the commissural pins
240aa, 240bb, and 240cc, respectively, of the valve cage stent 220,
thereby connecting the valve frame 232 (and thus the valve 230) to
the valve cage stent 220. As described below, the heart valve
prosthesis 210 incorporating the tri-leaflet valve 230 is delivered
using a catheter.
[0067] As shown in FIG. 3G, the valve cage stent 220 for use with
the tri-leaflet valve 230 has three different zones 221, 222, and
223 along its longitudinal axis, the different zones having
different geometric configurations so as to perform different
functions. The first, or center, zone 221 functions as the stent
connector, which is identical to the stent disclosed in Int'al
Patent Application No. PCT/US2006/043526, filed Nov. 9, 2006 (which
is based on U.S. Provisional Application No. 60/735,221), and which
connects to the native valve annulus. The second and third zones
222 and 223, at either end of the center zone 221, function
respectively as the superior valve rim carrying the commissural
pins in the tri-leaflet valve prosthesis 210 or the valve mount in
the bi-leaflet valve prosthesis 110, and the inferior valve skirt.
The valve skirt 223 provides additional support, as well as a
fabric/tissue attachment area to minimize leaking.
[0068] The present invention also encompasses a system and method
for implanting the above-described percutaneous valve prostheses 10
in the body. In a first embodiment, the system comprises a valve
cage stent 20 for implantation in the body by the use of a first
catheter of a delivery system 500 (shown in FIGS. 8A and 8B, and as
described in greater detail hereinafter) to provide a stable,
fixed, and sturdy frame within which an elastic, compressible valve
30 can be inserted and secured by a second catheter (not shown),
and the valve 30 is attached to the valve cage stent 20 after they
are discharged from their respective catheters. Performing the
procedure in two parts at the same session downsizes the devices
considerably, so that the procedure can be performed
percutaneously. In a second embodiment, the system comprises a
valve cage stent 20 and an elastic, compressible valve 30 which are
inserted using the same catheter, and the valve 30 is attached to
the valve cage stent 20 within the catheter, as shown in FIGS.
9A-9T.
[0069] The valve cage stent 20 is a self-expanding or balloon
expandable cylindrical valve cage stent 20, made from memory metal,
or stainless steel respectively. The self-expanding valve cage
stent and the balloon expandable valve cage stent are structurally
the same (that is, they differ only in the material from which they
are made). The valve cage stent 20 is fabricated from metal tubing
(memory metal or stainless steel), so that it is cylindrical in
shape, with the stent pattern being cut into the tubing by
laser.
[0070] The expansion of the valve cage stent 20 produces maximal
foreshortening of the ovals in the mid portion of the stent and
thus provides active fixation of the stent to the annulus of the
valve being replaced. The valve cage stent 20 has a fabric covering
on its interior and parts of its exterior surfaces so in its
expanded state it forms a complete seal and does not allow any
leakage of blood.
[0071] For delivery, the valve cage stent 20 is mounted on a
balloon 600 (FIG. 8), or in a restraining sheath if
self-expandable. The delivery system apparatus 500 is shown in
FIGS. 7A-7C. The delivery system apparatus 500 comprises a flexible
outer sheath 510, in which the valve cage stent 20 is inserted with
a first set of guide wires 520 attached thereto, followed by a
slotted nosecone 530 having another set of guide wires 540 attached
thereto.
[0072] The valve cage stent 20 has provisions for the attachment of
the prosthetic valve, depending on the type of prosthetic valve
contemplated to be used. For example, in the case of a bi-leaflet
valve, the valve is attached to the valve cage stent 120 via a
valve mount affixed to the valve cage stent 120, as shown in FIGS.
4D-4G and 5G-5I. In the case of a tri-leaflet valve, the valve is
attached to the valve cage stent 220 via engagement of the valve
commissural posts 240a, 240b, and 240c with the commissural pins
240aa, 240bb, and 240cc of the valve cage stent 220, as shown in
FIGS. 6H-6J.
[0073] The delivery system employs a two stage procedure, both
stages of which can be performed at the same session, only minutes
apart. The first stage is insertion of the valve cage stent 20. In
the case of a bi-leaflet valve, as shown in FIG. 4A, the valve cage
stent 120 has a valve mount connected thereto and a guide wire
connected to the valve mount. In the case of a tri-leaflet valve,
as shown in FIGS. 6A-6G and as described above, the valve cage
stent 220 has three commissural pins 240aa, 240bb, and 240cc
provided thereon and guide wires connected thereto.
[0074] The second stage is insertion of the elastic and
compressible valve, which is restrained in another catheter (not
shown) for delivery into the valve cage stent 20. As shown in FIGS.
4A-4D, 5A-5F, and 6A-6H, in the second stage, the valve is placed
over the guide wire (in the case of a bi-leaflet valve) or guide
wires (in the case of the tri-leaflet valve) connected to the valve
cage stent 20 in order to ensure proper positioning of the valve
relative to the stent. Once the valve is seated, the guide wire or
wires are withdrawn (FIGS. 4D-4G, 5G-5I, and 6I-6J).
[0075] Because the bi-leaflet valve is detachable from the valve
mount, it can be replaced when necessary. The valve mount has a
snap-on or screw-in mechanism for attachment of the "t"-shaped
hinge 135 thereto, as well as the above-described guide wire
attached to it for placement of the valve. The use of a valve cage
20 allows for fabrication of a tri-leaflet tissue valve.
[0076] In addition, the connection of valve 30 to the valve cage
stent 20 provides the best effective flow dynamics, the flexibility
of the whole system 500 is greatly increased, and the profile of
the whole system 500 is reduced so that it can be inserted through
a small opening in the access vessel.
[0077] Modifications and variations of the above-described
embodiments of the present invention are possible, as appreciated
by those skilled in the art in light of the above teachings. It is
therefore to be understood that, within the scope of the appended
claims and their equivalents, the invention may be practiced
otherwise than as specifically described.
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