U.S. patent application number 12/482781 was filed with the patent office on 2009-10-01 for injectable heart valve prosthesis for low-invasive implantation.
Invention is credited to SHLOMO GABBAY.
Application Number | 20090248149 12/482781 |
Document ID | / |
Family ID | 25521055 |
Filed Date | 2009-10-01 |
United States Patent
Application |
20090248149 |
Kind Code |
A1 |
GABBAY; SHLOMO |
October 1, 2009 |
INJECTABLE HEART VALVE PROSTHESIS FOR LOW-INVASIVE IMPLANTATION
Abstract
A heart valve prosthesis may include a cylindrical support
extending between axially spaced apart ends thereof, the
cylindrical support including a plurality of support features
extend generally axially between the opposed ends of the support,
adjacent pairs of the support features being interconnected so as
to bias the cylindrical support radially outwardly. A valve is
mounted within the support to define a supported valve. The
supported valve can include a sidewall portion extending between
inflow and outflow ends thereof, the inflow and outflow ends of the
valve sidewall portion being mounted within the cylindrical support
such that ends of the sidewall portion are spaced axially apart
from the spaced apart ends of the cylindrical support. The
supported valve can also include a valve portion residing within
the sidewall portion and configured to provide for substantially
unidirectional flow of blood through the supported valve, the
supported valve being deformable between a reduced cross-sectional
condition and an expanded cross-sectional condition, whereby
implantation of the supported valve is facilitated when in the
reduced cross-sectional condition.
Inventors: |
GABBAY; SHLOMO; (Boca Raton,
FL) |
Correspondence
Address: |
TAROLLI, SUNDHEIM, COVELL & TUMMINO L.L.P.
1300 EAST NINTH STREET, SUITE 1700
CLEVEVLAND
OH
44114
US
|
Family ID: |
25521055 |
Appl. No.: |
12/482781 |
Filed: |
June 11, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10266380 |
Oct 8, 2002 |
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12482781 |
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09973609 |
Oct 9, 2001 |
7510572 |
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10266380 |
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09659882 |
Sep 12, 2000 |
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09973609 |
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Current U.S.
Class: |
623/2.37 ;
623/2.36 |
Current CPC
Class: |
A61F 2230/0067 20130101;
A61F 2/2475 20130101; A61F 2/2418 20130101; A61F 2230/005 20130101;
A61F 2/2436 20130101; A61F 2210/0014 20130101; A61F 2/2409
20130101; A61F 2/2427 20130101; A61F 2220/0016 20130101; G01N
2800/52 20130101; A61F 2/2433 20130101; A61F 2230/0054 20130101;
A61F 2230/0078 20130101; Y10S 623/904 20130101 |
Class at
Publication: |
623/2.37 ;
623/2.36 |
International
Class: |
A61F 2/24 20060101
A61F002/24 |
Claims
1. A heart valve prosthesis comprising: a cylindrical support
extending between axially spaced apart ends thereof, the
cylindrical support including a plurality of support features
extend generally axially between the axially spaced apart ends of
the cylindrical support, adjacent pairs of the support features
being interconnected so as to bias the cylindrical support radially
outwardly; and a valve mounted within the cylindrical support to
define a supported valve, the supported valve comprising: a
sidewall portion extending between inflow and outflow ends thereof,
the inflow and outflow ends of the valve sidewall portion being
mounted within the cylindrical support such that ends of the
sidewall portion are spaced axially apart from the spaced apart
ends of the cylindrical support; and a valve portion residing
within the sidewall portion and configured to provide for
substantially unidirectional flow of blood through the supported
valve, the supported valve being deformable between a reduced
cross-sectional condition and an expanded cross-sectional
condition, whereby implantation of the supported valve is
facilitated when in the reduced cross-sectional condition.
2. The prosthesis of claim 1, further comprising biasing elements
that interconnect each adjacent pair of the support features, each
biasing element urging support features that are interconnected by
respective biasing element apart from each other as to bias the
cylindrical support radially outwardly.
3. The prosthesis of claim 2, the biasing elements further
comprising springs arranged in a generally circular array at the
axially spaced apart ends of the cylindrical support, the springs
interconnecting adjacent support features to bias the cylindrical
support radially outwardly.
4. The prosthesis of claim 3, the support features and the springs
being formed of a continuous length of a resilient material to
provide a cage-like support.
5. The prosthesis of claim 3, further comprising projections biased
to extend radially outwardly from at least one of the axially
spaced apart ends of the cylindrical support.
6. The prosthesis of claim 5, the projections further comprising a
plurality of triangular projections interconnected at the axially
spaced apart ends of the cylindrical support at the biasing
elements, each of the triangular projections being configured to
extend axially and radially outwardly from the respective opposed
ends beyond a radially outer extent of the cylindrical support.
7. The prosthesis of claim 1, further comprising a flexible
connecting element attached to the cylindrical support to inhibit
radial outward expansion of at least part of the cylindrical
support beyond a predetermined amount.
8. The prosthesis of claim 1, the cylindrical support further
comprising at least two generally cylindrical support portions
having adjacent ends connected substantially coaxially together,
the axially spaced apart ends of the cylindrical support define
axially opposed inflow and outflow ends of the cylindrical support,
the valve including an inflow end and an outflow end spaced apart
from each other on axially opposed sides of a juncture between the
at least two support portions.
9. The prosthesis of claim 8, further comprising an intermediate
connecting element that connects the support portions at the
juncture between the at least two support portions.
10. The prosthesis of claim 8, further comprising a plurality of
biasing elements that interconnect adjacent support features in
each of the support portions, the biasing elements urging the
interconnected support features apart from each other to provide
radial outward expansion of the respective at least two sidewall
portions.
11. The prosthesis of claim 10, the biasing elements being
connected by flexible connecting elements in a generally circular
arrangement at the axially spaced apart ends of each respective
support portion, the connecting elements inhibiting radial
expansion of the cylindrical support at the respective ends of the
support portions beyond a predetermined amount.
12. The prosthesis of claim 8, further comprising projections
extending axially and radially outwardly from the axially opposed
inflow and outflow ends of the cylindrical support.
13. The prosthesis of claim 12, the projections further comprising
triangular-shaped projections connected at each of the axially
opposed inflow and outflow ends of the cylindrical support in a
circular arrangement and configured to extend axially and radially
outwardly from the respective axially opposed inflow and outflow
ends of the cylindrical support.
14. The prosthesis of claim 1, further comprising an outer sheath
of a substantially biocompatible material that covers at least a
substantial portion of an exposed part of the cylindrical
support.
15. The prosthesis of claim 1, wherein the valve portion has an
axial length defined by a distance between the spaced apart ends of
the valve portion, the axial length of the valve portion being less
than the axial length of the cylindrical support and the valve
portion is connected to remain near a central axial position of the
cylindrical support such that the ends of the valve portion are
spaced axially apart from respective ends of the cylindrical
support.
16. The prosthesis of claim 15, wherein, in the expanded
cross-sectional condition, a cross-sectional dimension of the
cylindrical support at an axial position between an outflow end of
the valve and an outflow end of the cylindrical support is less
than a cross-sectional dimension of the cylindrical support and the
valve portion at an axial position where the valve portion
resides.
17. The prosthesis of claim 16, wherein, in the expanded
cross-sectional condition, a cross-sectional dimension of the
cylindrical support at an axial position between an inflow end of
the valve portion and an inflow end of the cylindrical support is
less than a cross-sectional dimension of both the cylindrical
support and the valve portion at an axial position where the valve
portion resides.
18. The prosthesis of claim 1 in combination with an implanter, the
combination comprising: the implanter comprising: a body portion;
and an elongated cylindrical member extending from the body portion
to terminate in a distal end thereof that is spaced apart from the
body portion, the distal end having an opening to a passage that
extends through at least a portion of the cylindrical member, at
least a distal end portion of the cylindrical member proximal the
distal end thereof being flexible to permit flexing or bending of
the distal end portion; and the prosthesis being mounted within the
cylindrical member in the reduced cross-sectional condition.
19. A heart valve prosthesis comprising: a cylindrical support
extending between axially spaced apart inflow and outflow ends
thereof, the cylindrical support including a plurality of support
features extend generally axially between the axially spaced apart
inflow and outflow ends of the cylindrical support, adjacent pairs
of the support features being interconnected so as to bias the
cylindrical support radially outwardly; and a valve mounted within
the cylindrical support to define a supported valve, the supported
valve being configured to provide for substantially unidirectional
flow of blood through the supported valve, the valve having inflow
and outflow ends that are spaced axially apart from the respective
inflow and outflow ends of the cylindrical support, the supported
valve being deformable between a reduced cross-sectional condition
and an expanded cross-sectional condition, wherein, in the expanded
cross-sectional condition, a cross-sectional dimension of the
cylindrical support at an axial position between an outflow end of
the valve and an outflow end of the cylindrical support is less
than a cross-sectional dimension of the cylindrical support and the
valve at an axial position where the valve resides. 20. The
prosthesis of claim 19 in combination with an implanter, the
combination comprising: the implanter comprising: a body portion;
and an elongated cylindrical member extending from the body portion
to terminate in a distal end thereof that is spaced apart from the
body portion, the distal end having an opening to a passage that
extends through at least a portion of the cylindrical member, at
least a distal end portion of the cylindrical member proximal the
distal end thereof being flexible to permit flexing or bending of
the distal end portion; and the prosthesis being mounted within the
cylindrical member in the reduced cross-sectional condition.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application is continuation of U.S. patent application
Ser. No. 10/266,380, which was filed Oct. 8, 2002 and entitled
HEART VALVE PROSTHESIS AND SUTURELESS IMPLANTATION OF A HEART VALVE
PROSTHESIS, which is a continuation-in-part of U.S. patent
application Ser. No. 09/973,609, now U.S. Pat. No. 7,510,572, which
was filed on Oct. 9, 2001, and entitled HEART VALVE PROSTHESIS AND
SUTURELESS IMPLANTATION OF A HEART VALVE PROSTHESIS, which is a
continuation-in-part of U.S. patent application Ser. No.
09/659,882, which was filed on Sep. 12, 2000 and entitled VALVULAR
PROSTHESIS AND METHOD OF USING SAME. Each of the above-identified
applications is incorporated herein by reference.
TECHNICAL FIELD
[0002] The invention relates to an implantable prosthetic device
and, more particularly, to a heart valve prosthesis that can be
implanted via a low-invasive procedure.
BACKGROUND
[0003] It is well known to utilize mechanical heart valves, such as
the ball check valve, and natural tissue cardiac valves to replace
defective aortic and mitral valves in human patients. One type of
natural tissue heart valve typically employs a porcine valve for
implantation in a human, as they are very similar to human valves
of appropriate size and generally are easy to procure. Typically,
the porcine valve is fixed by chemically treating it, such as with
an appropriate glutaraldehyde solution. The treated porcine valve
further may be mounted into a stent to support the valve at a fixed
position.
[0004] A stent typically is formed of a resilient material, such as
a plastic (e.g., DELRIN). Examples of various stent structures are
disclosed in U.S. Pat. No. 3,983,581, U.S. Pat. No. 4,035,849. The
stent usually is covered with a fabric material, such as DACRON or
a suitable textile material. The fabric material provides structure
for securing the valve relative to the stent. The stented heart
valve prosthesis may be implanted into a patient for a heart valve
replacement.
[0005] In order to surgically implant a heart valve into a patient,
the patient typically is placed on cardiopulmonary bypass during a
complicated, but common, open chest procedure. In certain
situations, an individual requiring a heart valve replacement may
be sufficiently ill, such that placing the individual on
cardiopulmonary bypass may pose too great of risk. Such individuals
may correspond to a class of patients who may have a
non-functioning pulmonary valve or severe aortic valve
insufficiency. In particular, many older patients having a
deficient aortic or pulmonic valve may be too ill to survive
conventional open-heart surgery.
[0006] Patients exhibiting these and other conditions would benefit
from an improved heart valve prosthesis that may be implanted by a
less invasive and/or more efficient implantation procedure.
SUMMARY
[0007] The following presents a simplified summary of the invention
in order to provide a basic understanding of some aspects of the
invention. This summary is not an extensive overview of the
invention. It is intended to neither identify key or critical
elements of the invention nor delineate the scope of the invention.
Its sole purpose is to present some concepts of the invention in a
simplified form as a prelude to the more detailed description that
is presented later.
[0008] The invention relates to an implantable prosthetic device
and, more particularly, to a heart valve prosthesis, such as can be
implanted via a low-invasive procedure.
[0009] One aspect of the invention provides a heart valve
prosthesis that includes a cylindrical support extending between
axially spaced apart ends thereof, the cylindrical support
including a plurality of support features extend generally axially
between the opposed ends of the support, adjacent pairs of the
support features being interconnected so as to bias the cylindrical
support radially outwardly. A valve is mounted within the support
to define a supported valve. The supported valve can include a
sidewall portion extending between inflow and outflow ends thereof,
the inflow and outflow ends of the valve sidewall portion being
mounted within the cylindrical support such that ends of the
sidewall portion are spaced axially apart from the spaced apart
ends of the cylindrical support. The supported valve can also
include a valve portion residing within the sidewall portion and
configured to provide for substantially unidirectional flow of
blood through the supported valve, the supported valve being
deformable between a reduced cross-sectional condition and an
expanded cross-sectional condition, whereby implantation of the
supported valve is facilitated when in the reduced cross-sectional
condition
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] To the accomplishment of the foregoing and related ends,
certain illustrative aspects of the invention are described herein
in connection with the following description and the annexed
drawings. These aspects are indicative, however, of but a few of
the various ways in which the principles of the invention may be
employed and the present invention is intended to include all such
aspects and their equivalents. Other advantages and novel features
of the invention will become apparent from the following detailed
description of the invention when considered in conjunction with
the drawings, in which:
[0011] FIG. 1 is an exploded isometric view of a valve and stent
apparatus that may be utilized to form a prosthesis in accordance
with the present invention.
[0012] FIG. 1A is an enlarged view of part of the stent of FIG. 1
in a first condition.
[0013] FIG. 1B is an enlarged view of part of the stent of FIG. 1,
similar to FIG. 1A, illustrating the part of the stent in a second
condition.
[0014] FIG. 2 is an example of a valvular prosthesis in accordance
with the present invention.
[0015] FIG. 3 is another example of valvular prostheses in
accordance with the present invention.
[0016] FIG. 4 is an example of the valvular prostheses of FIG. 3
implanted within a tubular member in accordance with the present
invention.
[0017] FIG. 5 is another example of a stent apparatus in accordance
with the present invention.
[0018] FIG. 6A is an example of the stent of FIG. 5 mounted within
an enclosure in accordance with the present invention.
[0019] FIG. 6B is an example of valvular prostheses having the
stent of FIG. 5 mounted therein in accordance with the present
invention.
[0020] FIG. 7 is an example of a valvular prosthesis, illustrating
an outer sheath over the prosthesis of FIG. 6B in accordance with
the present invention.
[0021] FIG. 8 is another example of a valvular prosthesis,
illustrating an outer sheath over the prosthesis of FIG. 6B in
accordance with the present invention.
[0022] FIG. 9A is an example of enclosure that may be utilized for
implanting a valvular prosthesis in accordance with the present
invention.
[0023] FIG. 9B is an example of another enclosure catheter
mechanism that may be utilized for implanting a valvular prosthesis
in accordance with the present invention.
[0024] FIG. 10 is an example of a valvular prostheses implanted in
an aortic position of a heart in accordance with the present
invention.
[0025] FIG. 11 is an example of a valvular prostheses implanted in
a pulmonic position of a heart in accordance with the present
invention.
[0026] FIG. 12 is an example of a support structure in accordance
with an aspect of the present invention.
[0027] FIG. 13 is an example of another support structure in
accordance with an aspect of the present invention.
[0028] FIG. 14 is an example of a heart valve prosthesis employing
the support structure in accordance with an aspect of the present
invention.
[0029] FIG. 15 is a cross-sectional view of a heart valve
prosthesis taken along line 15-15 in FIG. 14.
[0030] FIG. 16 is an example of another type of support structure
in accordance with an aspect of the present invention.
[0031] FIG. 17 is another example of a heart valve prosthesis
employing the support structure of FIG. 16 in accordance with an
aspect of the present invention.
[0032] FIG. 18 is an example of a heart valve prosthesis employing
a support structure in accordance with an aspect of the present
invention.
[0033] FIG. 19 is an example of an implanter apparatus for
implanting a prosthesis in accordance with an aspect of the present
invention.
[0034] FIG. 20 is an enlarged view of part of the implanter
apparatus of FIG. 19. FIG. 21 is an example of a prosthesis being
implanted at a desired location in accordance with an aspect of the
present invention.
[0035] FIG. 22 is an example of a prosthesis mounted at a pulmonary
position of a patient's heart in accordance with an aspect of the
present invention.
[0036] FIG. 23 is an example of a valve being implanted at the
aortic position in accordance with an aspect of the present
invention.
[0037] FIG. 24 is an example of a valve being implanted at the
pulmonic position in accordance with an aspect of the present
invention.
[0038] FIG. 25 is an example of another type of support structure
in accordance with an aspect of the present invention.
[0039] FIG. 26 is an example of a heart valve prosthesis employing
the support structure of FIG. 26 in accordance with an aspect of
the present invention.
[0040] FIG. 27 is an example of a heart valve prosthesis being
implanted in accordance with an aspect of the present
invention.
DESCRIPTION OF THE INVENTION
[0041] FIG. 1 is an exploded view of a valvular prosthesis 10 in
accordance with an aspect of the present invention. The prosthesis
10 includes a valve portion 12 and a stent portion 14 that may be
assembled to form the valvular prosthesis 10, such as shown in FIG.
2.
[0042] The valve portion 12 includes inflow and outflow ends 16 and
18 spaced apart from each other by a length of a generally
cylindrical sidewall portion 20. While the inflow and outflow ends
16 and 18 are illustrated as being annular in FIGS. 1 and 2, those
skilled in the art will understand and appreciate that other
configurations (e.g., generally sinusoidal ends) also could be used
in accordance with the present invention.
[0043] The valve portion 12 also includes one or more leaflets 22,
24, and 26 that are attached to and extend from an interior of the
sidewall portion 20. In the example illustrated in FIGS. 1 and 2,
the valve portion 12 includes three leaflets 22, 24 and 26,
although other numbers of leaflets, such as a single leaflet or two
leaflets, also could be used.
[0044] The valve portion 12 may be formed of any substantially
biocompatible valve apparatus. By way of example, the valve portion
12 may include an animal heart valve (e.g., pulmonic or aortic), a
manufactured valve device (e.g., a valve as shown and described in
U.S. Pat. No. 4, 759,758 or U.S. Pat. No. 5,935,163) a venous valve
(e.g., a bovine or equine jugular venous valve). Those skilled in
the art will understand and appreciate that the foregoing list is
not intended to be exhaustive but, instead, is intended illustrate
a few examples of the types of valves that may be utilized in a
valvular prosthesis 10 in accordance with an aspect of the present
invention.
[0045] If the valve portion 12 is formed of a natural tissue
material, such as an animal heart valve, a venous valve, or a
composite valve manufactured of natural tissue, the valve should be
chemically fixed, such as in a suitable solution of glutaraldehyde
in a closed condition (as is known in the art). The fixation
process facilitates closure of the valve 12 under application of
back flow pressure, while remaining open during normal forward
blood flow through the valve 12. By way of example, the natural
tissue valve may be cross-linked with glutaraldehyde and undergo a
detoxification process with heparin bonding. The treatment improves
biocompatibility of the valve apparatus 12 and mitigates
calcification and thrombus formation.
[0046] In accordance with an aspect of the present invention, the
valve portion 12 exhibits structural memory. That is, if the valve
apparatus 12 is compressed, such as to a reduced diameter at the
time of being implanted, it will return substantially to its
original shape and configuration upon removal of radially inward
forces. As a result, the valve apparatus 12 is able to maintain
coaptation of the leaflets 22, 24, and 26 even after being
deformed. The memory feature of the valve is further improved by
mounting it within the stent portion 14.
[0047] Turning now to the stent portion 14, such as shown in FIGS.
1 and 2, the stent includes an inflow end 30 and an outflow end 32.
In this example, the inflow and outflow ends 30 and 32 are spaced
apart from each other a distance that is greater than the distance
between the corresponding ends 18 and 16 of the valve 12. In this
way, the ends of the stent 30 and 32 may extend beyond the
respective ends 18 and 16 of the valve 12 (e.g., by about a few
millimeters), such as shown in FIG. 2. The stent portion 14 also
may include outwardly turned portions at the inflow and outflow
ends 30 and 32 of the stent, which, when implanted, may engage
and/or be urged into the surrounding tissue to mitigate movement
thereof.
[0048] According to an aspect of the present invention, the stent
14 may deformable between first and second conditions, in which the
first condition has a reduced cross-sectional dimension relative to
the second condition. FIGS. 1 and 2 illustrate the stent portion 14
as being formed of a mesh or weave 34 extending between the ends 30
and 32. The mesh 34 may be a metal, an alloy, or other suitable
material that may help support a valve mounted therein and/or help
anchor the valve at a desired position when implanted.
[0049] By way of example, the mesh may be formed of a shape memory
alloy material, such as may be formed of a nitinol (nickel-titanium
alloy) wire. Shape memory (or thermal memory) is a characteristic
in which a deformed part remembers and recovers to a pre-deformed
shape upon heating. By forming the stent 14 of a shape memory
alloy, the stent is inelastically deformable to new shape, such as
a reduced cross-sectional dimension, when in its low-temperature
(martensitic) form. For example, the stented valve (FIG. 2) may be
cooled, such as by being introduced to a cooling solution (e.g.,
water), and then compressed.
[0050] When the stent 14 is heated to its transformation
temperature, which may vary according to the alloy composition, it
quickly reverts to its high-temperature (austenitic) form. The
stented valve may retain the compressed condition by keeping it
cooled. Alternatively, the stent and valve may be retained in the
compressed position, such as with sutures circumscribing the
structure, a cylindrical enclosure around the structure, etc. The
prosthesis 10 will then return toward its high-temperature (or
original) position upon removal of the retaining element.
[0051] It is to be appreciated that, alternatively, the stent 14,
in accordance with an aspect of the present invention, could be
inelastically deformable so as to require an intervening force to
return the deformed stent substantially to a desired configuration.
For example, a balloon catheter or spring mechanism could be
employed to urge the stent and the valve located therein generally
radially outward so that, after being implanted to a desired
position, the stent will engage the surrounding tissue in a manner
to inhibit movement relative to the surrounding tissue.
[0052] FIGS. 1A and 1B illustrate an enlarged view of part of the
stent 14 in accordance with an aspect of the present invention. In
this example, some strands of the mesh 34 are broken to define
spaces 36 between adjacent lateral extensions or spike portions 38
and 40. As the stent 14 is deformed, such as shown in FIG. 1B, the
spike portions 38' and 40' may extend radially outwardly from the
stent in different directions. In addition, the inflow end 32' also
may flare outwardly for engagement with surrounding tissue when
implanted. For example, some spikes 40, 40' may extend generally
outwardly and toward an outflow end of the stent 14, while others
38, 38' may extend generally outwardly and toward an inflow end 32,
32'. The spikes thus are operable to engage tissue, when implanted,
so as to inhibit axial movement of the stent 14 relative to the
surrounding tissue.
[0053] Referring back to FIG. 2, the valve portion 12 is disposed
generally coaxially within the cylindrical stent portion 14
relative to the central axis A. The valve 1 2 may be affixed
relative to the stent portion 14, such as by one or more sutures
44. The sutures 44 may be located at the inflow and outflow ends 16
and 18 of the valve 12 to connect the valve to the stent 14 to
inhibit axial movement of the valve relative to the stent.
Alternatively or additionally, axial movement between the stent 14
and valve 12 may be mitigated due to friction fitting between the
stent and valve portion. For example, as illustrated in FIG. 2, the
valve portion 12 has a cross-sectional diameter that is slightly
larger than that of the stent 14, such that the prosthesis 10
bulges somewhat in the middle and is narrower near the inflow and
outflows ends 16 and 18 of the valve portion 12.
[0054] As mentioned above, the stent portion 14 may be formed of a
shape memory alloy. In this way, the valvular prosthesis 10 may be
compressed to a reduced cross-sectional dimension about the axis A
and maintained at the reduced dimension while being implanted. Once
the valvular prosthesis 10 is at a desired implantation position,
the prosthesis may be permitted to return toward its original
cross-sectional dimension so as to engage a valve wall or other
surrounding tissue at the desired position. The engagement between
the stented valvular prosthesis 10 and the surrounding tissue
inhibits axial movement of the prosthesis relative to the tissue.
In accordance with an aspect of the present invention, lateral
extensions or spikes (see, e.g., FIGS. 1A and 1B) may extend
outwardly from the stent to further inhibit axial movement. Those
skilled in the art will understand and appreciate that a valvular
prosthesis 10, in accordance with the present invention, may be
utilized to replace a heart valve or utilized as an intravascular
implant to provide an operable venous valve.
[0055] FIG. 3 illustrates another example of a stented valvular
prosthesis 50 in accordance with an aspect of the present
invention. The prosthesis 50 in this example includes a valve
portion 52 mounted within a stent portion 54. The valve portion 52
in this example, has a generally sinusoidal outflow end 56 having a
plurality of commissure posts 58, 60, and 62 extending from an
annular base portion 64, with corresponding sinuses located between
each adjacent pair of posts. It is to be appreciated that,
alternatively, a valve having a sidewall portion according to
generally cylindrical configuration of FIGS. 1 and 2 also could be
used in conjunction with the stent portion 54.
[0056] The stent portion 54 in this example is formed of a
deformable mesh, which may be substantially identical to that
described above with respect to FIGS. 1-2. The stent portion 54
also includes a plurality of spikes extending generally radially
outwardly from the stent portion. In particular, one set of spikes
66 extend from an inflow end 68 of the stent portion 54 and another
set of spikes 70 extend from an outflow end 72 of the stent.
[0057] FIG. 4 illustrates the prosthesis 50 of FIG. 3 mounted in an
expanded condition within a generally cylindrical sidewall 74. The
sidewall 74, for example, may be a venous valve wall, a pulmonary
artery, an aorta, etc. In this example, the spikes 66 and 70 engage
and/or extend into the valvular wall 74 to inhibit axial movement
of the prosthesis 50 relative to the valve wall 74.
[0058] FIG. 5 illustrates another example of a stent apparatus 80
which may be utilized as part of a valvular prosthesis in
accordance with an aspect of the present invention. The stent 80
includes a generally annular base portion 82 and a plurality of
axially extending portions (or stent posts) 84, 86 and 88 extending
generally axially from the base portion. The post portions 84, 86
and 88 are circumferentially spaced apart for generally radial
alignment with corresponding commissure posts of an associated
valve wall. While the example of the stent 80 in FIG. 5 has three
stent posts 84, 86 and 88, those skilled in the art will understand
and appreciate that other numbers of posts also could be utilized
in accordance with an aspect of the present invention. Typically,
however, the number of posts and their relative circumferential
position correspond to the number of leaflets of a valve to be
mounted within the stent 80.
[0059] In accordance with an aspect of the present invention, each
of the stent posts 84, 86, 88 may extend radially outwardly an
angle .THETA. relative to the axis A. By way of example, the angle
.THETA. may range from about 10 to about 60 degrees relative to a
line drawn through the juncture of each post and the base 82
parallel to the central axis A. The outwardly extending posts 84,
86, and 88 facilitate engagement between each respective post and
surrounding tissue when implanted, as the posts (being resilient)
tend to urge radially outwardly and into engagement with such
tissue.
[0060] The stent 80 also includes a plurality of spikes 90 and 92
that extend radially outwardly from the stent. In particular, some
outwardly extending spikes 90 are curved generally toward an
outflow end of the stent and others 92 are curved generally toward
an inflow end of the stent. In addition, a row of spikes 90 may
extend outwardly relative to the stent 80 at the inflow end
thereof, which spikes also are curved generally toward the outflow
end. The varying contour of the spikes 90 and 92 mitigates axial
movement of the stent 80 (in both axial directions) relative to
tissue engaged thereby, such as after being implanted. It is to be
understood and appreciated that, while a single row of spikes is
illustrated near the inflow end of the stent in FIG. 5, two or more
axially spaced apart rows of spikes extending generally radially
outwardly from the stent 80 could also be utilized in accordance
with an aspect of the present invention. The rows of spikes may be
curved toward each other to provide a clamping function on
surrounding tissue when implanted.
[0061] FIG. 6A illustrates the stent of FIG. 5 mounted within a
tubular structure 94 that has an inner diameter that is
substantially commensurate with the outer diameter of the base
portion 82 of the stent 80. The tubular structure 94 may be formed
of a plastic or other material effective to hold the stent posts
84, 86, and 88 at a radial inward position. In this way, the
tubular structure 94 urges the stent posts 84, 86, and 88 radially
inward to a position that facilitates mounting a valve 98 therein.
For example, the valve 98 may be positioned within and connected to
the stent 80, such as by sutures applied along the base portion 82
and the stent posts 84, 86, and 88; without having to manually hold
each of the posts against corresponding parts of the valve.
[0062] FIG. 6B illustrates an example in which a valve 98 has been
mounted within the stent 80 of FIG. 5 to form a valvular prosthesis
100. The valve 98 includes an inflow end 102 and an outflow end
104. The inflow end 102 of the valve 98 is positioned adjacent
relative to the inflow end of the stent 80. The outflow end 104 of
the valve 98 is contoured to include axially extending commissure
posts 106, 108 and 110 with sinuses 112, 114 and 116 located
between each adjacent pair of posts. Valve leaflets 118, 120 and
122 extend between adjacent posts commensurate with the location of
each of the sinuses 112, 114 and 116. The stent 80 may be connected
to the valve 98 via sutures 124.
[0063] In accordance with an aspect of the present invention, the
prosthesis 100 of FIG. 6B is a stented valve, which may be covered
with an outer sheath of a substantially biocompatible material.
[0064] FIG. 7 illustrates an example of a valvular prosthesis in
which an outer sheath 130 has been applied over the stent 80 and at
least part of the exposed exterior portion of the valve 98 in
accordance with an aspect of the present invention. As illustrated,
the outer sheath 130 may have inflow and outflow ends having
generally the same contour as the sidewall of the valve 98 and the
stent 80. The outer sheath 130 may be a sheath of natural tissue
pericardium (e.g., bovine, equine, porcine, etc.), another
biological tissue material (e.g., collagen), or a synthetic
material (e.g., Dacron). When a biological tissue is utilized, for
example, it may be cross-linked with glutaraldehyde and detoxified
with heparin bonding.
[0065] An implantation flange (or sewing ring) 132 may be formed at
the inflow end of the prosthesis 100. The implantation flange 132
may be formed of substantially the same material as the outer
sheath 140, such as formed from the outer sheath 130 or by
attaching a separate flange by other methods. The outer sheath 130
may be attached to the valve 98 and/or to the stent 80 by applying
sutures 134 and 136 at the respective inflow and outflow ends of
the prosthesis 100. Some of the spikes 90, 92 may extend through
the outer sheath 130 so as to mitigate axial movement of the
prosthesis 100 relative to surrounding tissue when the prosthesis
is implanted. Sutures 134 and 136 may be applied respectively at
the inflow and outflow ends to secure the outer sheath relative to
the stent 80 and the valve 100. The outer sheath 130 may include an
outflow end that conforms to the contour of the outflow end 104 of
the valve 100.
[0066] FIG. 8 illustrates another example of valvular prosthesis
100 that is similar to that shown and described in FIG. 7, in which
identical reference numbers refer to corresponding parts previously
identified herein. The prosthesis 100 includes having an outer
sheath 140 that is disposed about the stent 80 and the valve 98 and
having an outflow end that follows the contour of the prosthesis
100 (e.g., generally sinusoidal. In addition, the outer sheath 140
includes a plurality of axially extending lobes 142, 144 and 146
extending axially beyond the outflow attachment of the valve
leaflets 118, 120, and 122. In this example, the lobes 142, 144 and
146 extend axially a length beyond the commissure posts 106, 108
and 110 of the valve 98. The axially extending lobes 142, 144 and
146 provide additional structure that may be utilized to help
secure the prosthesis 100 relative to surrounding tissue when being
implanted. When the prosthesis 100 of FIG. 8 is implanted, for
example, sutures may be applied through the lobes 142, 144 and 146
to help secure the commissure posts of the prosthesis relative to
the surrounding tissue. Additional sutures also could be applied at
the inflow end to the implantation flange 132 located thereat.
[0067] FIGS. 9A and 9B illustrate variations of an implantation
apparatus 200 that may be utilized to implant a valvular prosthesis
202 in accordance with an aspect of the present invention. It is to
be understood and appreciated that any of the prosthesis shown
and/or described herein may be implanted with such an implantation
apparatus. With reference to FIG. 9A, by way of example, the
implantation apparatus 200 may be in the form of a catheter system.
The implantation apparatus includes an elongated connecting element
204 extending between a trigger mechanism 206 and an enclosure 208,
in which the prosthesis 202 is located. At least a portion of the
prosthesis 202 is located within the enclosure 208. A plunger
mechanism 210 is located at a proximal end of the enclosure 208 for
urging the prosthesis 202 generally axially from the enclosure 208.
An opposite end 212 of the enclosure 208 may be formed of a pliable
material or a plurality of moveable members that may open as the
prosthesis 202 is urged through an opening 214 located at a distal
end. It is to be appreciated that the length of the connecting
element 204 may vary according to where the valvular prosthesis 202
is to be implanted and the method of implantation.
[0068] The valvular prosthesis 202 is illustrated within the
enclosure 208 in a compressed condition, such as described above.
That is, the valvular prosthesis 202 within the enclosure 208 has a
cross-sectional dimension that is less than its normal
cross-sectional dimension, being maintained in such position by the
enclosure. Those skilled in the art will appreciate that the
orientation of the valvular prosthesis 202 will vary depending upon
the direction in which blood is to flow through the valve when
implanted.
[0069] By way of example, the external stent of the valvular
prosthesis 202 may be formed of a deformable material, such as a
shape memory alloy material (e.g., nitinol), which maintains its
shape when cooled. Accordingly, the prosthesis 202 may be cooled
(e.g., within a suitable fluid), compressed to a desired reduced
cross-sectional dimension so as to fit within the enclosure 208,
and then inserted within the enclosure. The prosthesis 202, after
the stent being heated (e.g. to an ambient temperature), may desire
to expand to its original dimension and configuration. However, the
enclosure 208 or another retaining mechanism, such as a suture or
other tubular member around the prosthesis, may be used to restrict
its expansion. The compression of the valvular prosthesis 202 may
be performed just prior to surgery to mitigate undesired permanent
deformation of the valvular prosthesis 202. The plunger mechanism
may be urged in the direction of arrow 220, such as by activating
the trigger 206. Movement of the plunger 210, in turn, causes the
prosthesis 202 to also be moved in the direction of the arrow 220.
As the prosthesis 202 is urged through the opening 214 and
discharged therefrom, the prosthesis may expand. Accordingly, the
opening 214 should be positioned at the location where the
prosthesis 202 is to be implanted prior to discharge. When the
prosthesis 202 expands toward its original condition, the sidewall
of the stent and/or spikes associated with the stent may engage
and/or be urged into surrounding tissue so as to mitigate axial
movement of the prosthesis relative to the surrounding tissue. As a
result, the prosthesis may be implanted without sutures to provide
an operable valve, such as a heart valve or a venous valve. When a
valvular prosthesis is being employed as a heart valve, in
accordance with present invention, it will be appreciated that the
prosthesis may be implanted either as part of an open chest
procedure or the patient's chest may be closed. Additionally, other
expandable stent structures also could be utilized in accordance
with an aspect of the present invention.
[0070] FIG. 9B illustrates another example of an enclosure 208
which may be utilized, in accordance with an aspect of the present
invention, to implant a prosthesis 202. The enclosure 208 has an
opening 224 at its distal end through which the prosthesis 202 may
be discharged. In this example, the opening 224 is about the same
diameter as the enclosure itself, although it may be curved
slightly inwardly at the distal end thereof. This facilitates
discharge of the prosthesis 202 without having an expandable distal
end portion, such as shown and described with respect to FIG.
9A.
[0071] FIG. 10 illustrates an example of a valvular prosthesis 300
implanted in a heart 302 in an aortic position. When being
implanted at an aortic position, an aortic valve (e.g., equine,
porcine, bovine, etc.) may be utilized for the valve portion of the
prosthesis, although other types of valve portions also could be
used. Prior to implanting the prosthesis 300, the aortic valve or
at least calcified portions thereof should be removed. An inflow
end 304 of the prosthesis 300 is annularized with respect to the
annulus of the aorta 306. An outflow portion 308 of the prosthesis
300 extends axially into the aorta 306, with the stent posts
engaging the interior of the aortic wall. As mentioned above, a
plurality of spikes 310 may extend laterally from the stent portion
of the valvular prosthesis 300 to engage the aorta 306 to help
maintain a desired axial orientation of the valvular prosthesis
relative to the aorta 306.
[0072] The valvular prosthesis 300 may be implanted in a compressed
condition. It is to be appreciated that the valvular prosthesis 300
may be implanted in the aortic position during a conventional open
chest procedure or during a closed chest procedure. The valvular
prosthesis 300 may be implanted by using a catheter (or other
structure) to retain the prosthesis in a compressed condition. The
catheter may then be used to position the valve at a desired
position, such as by utilizing a suitable imaging technology (e.g.,
x-ray, ultrasound, or other tomography device) or a direct line of
sight. Once at the desired position, the prosthesis 300 may be
discharged from its retaining mechanism (e.g., an enclosure) so
that it expands toward its original expanded configuration at the
desired position within the aorta 306.
[0073] It is to be understood and appreciated, though, if the
patient has a calcified aortic valve, the patient typically must be
put on cardiopulmonary bypass to remove the calcium and implant the
valve. Advantageously, a valvular prosthesis 300 in accordance with
the present invention may be implanted more efficiently so as to
mitigate morbidity and mortality of the patient. In addition, the
prosthesis may be implanted without sutures or, alternatively, some
sutures may be utilized. For example, sutures may be applied at the
inflow end 304 (e.g., at a sewing ring) and/or at the outflow end
308, such as when the prosthesis is configured to have axially
extending lobes (see FIG. 8).
[0074] FIG. 11 illustrates an example of a valvular prosthesis 350
implanted in a pulmonary position of a heart 352. The particular
example illustrated in FIG. 11 shows an enclosure 353, such as may
be part of a catheter, which has been inserted into the heart 352
to place the prosthesis at a desired position. Specifically, the
catheter has traveled through the inferior vena cava 354, into the
right atrium 356 and into the right ventricle 358 to position the
valvular prosthesis 350 at a desired position relative to the
pulmonary artery 360.
[0075] As mentioned above, the prosthesis 350 is mounted within the
enclosure 353 in a compressed condition prior to implantation. The
enclosure 353 and the prosthesis 350, for example, may be
introduced into the inferior vena cava through the patient's right
femoral vein. The prosthesis 350 and enclosure 353 may traverse the
vascular system to the inferior vena cava 354 with the assistance
of suitable imaging equipment such as x-ray, ultrasound, or other
imaging devices. The imaging equipment is utilized to navigate the
enclosure 353 and the prosthesis 350 to the desired position. Once
at the desired position, such as at the opening to the pulmonary
artery 360, the prosthesis 350 may be discharged through a distal
opening of the enclosure 353. The valvular prosthesis 350 then
expands from its compressed condition to an expanded condition, as
illustrated in FIG. 11. Advantageously, when the valvular
prosthesis 350, which is formed of an elastic material (e.g.,
nitinol in its heated form), is urged through the opening of the
enclosure 353, it will automatically expand and dilate, thereby
also expanding the valve that is attached to the stent. Therefore,
the valvular prosthesis 350 becomes functional almost immediately.
The enclosure 353 may then removed out of the heart 352, through
the inferior vena cava 354 and removed from the patient.
[0076] Advantageously, the valvular prosthesis 350 may be implanted
in the patient without cardiopulmonary bypass. As a result, a
significant amount of time may be saved with less stress on the
patient, thereby mitigating the risks of morbidity and mortality
associated with conventional open-heart surgery typically employed
to implant a heart valve prosthesis. Those skilled in the art will
understand and appreciate that this process also may be utilized to
implant a valvular prosthesis for a venous valve, such as in a
patient's lower limb.
[0077] FIG. 12 illustrates another support structure 400 that can
be employed as part of a heart valve prosthesis in accordance with
an aspect of the present invention. The support 400 has a generally
cylindrical configuration that extends between spaced apart ends
402 and 404. A plurality of interconnected support features 406
extend generally axially between the ends 402 and 404. The support
features 406, for example, are formed of a length of a resilient
rod or wire (e.g., nitinol, surgical steel, aluminum, a polymer,
and the like). Biasing elements 408, such as coil springs,
interconnect at least some of the support features 406 at the
respective ends 402 and 404. The biasing elements 408, for example,
are arranged in a circular array spaced circumferentially apart
from each other at the respective ends 402 and 404. The biasing
elements 408 urge each pair features 406 interconnected by the
respective biasing elements apart from each other in a
circumferential direction. As a result of the circumferential
expansion between features 406 imposed by the biasing elements 408,
the cylindrical support 400 tends to expand radially outwardly.
Additionally or alternatively, the support 400 can be integrally
formed from a single piece of material configured to a desired
shape and configuration. For example, such an integral structure
can be formed via laser ablation from a tube a suitable from a
metal, such as nitinol.
[0078] The support 400 also includes one or more retaining elements
410 that inhibit radial expansion of the support beyond a certain
desired amount defined by the length of the retaining elements 410.
For example, the retaining element 410 can be in the form of one or
more flexible cords (e.g., sutures) that limit circumferential
expansion of the features 406 caused by the biasing elements 408.
In the example in FIG. 12, cords are in the form of flexible loop
of material attached to the biasing elements 408 located at each
end 402, 404 of the support 400. The cords further are threaded
through apertures of each of the biasing elements, although the
cords could be connected at the ends 402 and 404 by other
attachment arrangements. For example, one or more cords could be
threaded between adjacent support features an axial location
between the ends 402 and 404. Alternatively, other types of
flexible retaining mechanisms (e.g., a strip of treated animal
tissue, fabric, etc.) could be attached to the support 400 to limit
its circumferential expansion, although still permit a desired
reduction in its cross-sectional dimension.
[0079] FIG. 13 illustrates another example of a generally
cylindrical support structure 420 that could be used to form a
heart valve prosthesis in accordance with an aspect of the present
invention. The support 420 is similar to the support shown and
described with respect to FIG. 12 and, for example, can be formed
of the same or similar materials, as described with respect to FIG.
12. Briefly stated, the support includes a cylindrical intermediate
portion 422 having spaced apart ends 424 and 426. The intermediate
portion 422 includes a plurality of interconnected support features
428 that extend generally axially between the ends 424 and 426. At
least some of the features 428 are interconnected with adjacent
features by biasing elements 430 located at the juncture between
adjacent interconnected features. While the biasing elements 430
are illustrated as being located at the ends 424 and 426, it is to
be understood and appreciated that they alternatively could be
located between adjacent features at a different axial position
(e.g., intermediate) somewhere between an adjacent pair of features
in accordance with an aspect of the present invention.
[0080] The support 420 also includes retaining features 432 that
limit the circumferential expansion of the support to a desired
amount. The retaining feature 432 is in the form of a pair of cords
(e.g., sutures) having ends connected together to form a loop that
is connected at each end 424 and 426 of the support. Each loop 432
is flexible to permit the support to be deformed into a reduced
cross-sectional dimension. The loops 432 also inhibit expansion at
each of the ends 424 and 426 according to the dimensions of the
respective loops. For example, one end 426 (e.g., the inflow end)
can have a larger maximum diameter than the other end 424 (e.g.,
the outflow end) of the intermediate portion 422.
[0081] The support 420 further includes members 440 and 442 that
extend axially and radially outwardly from the respective ends 424
and 426 of the support. In this example, each of the members 440
and 442 includes a plurality of triangular projections 444. Each
projection 444 includes a pair of legs 446 that are connected to
the respective ends 440 and 442. The legs 446 extend radially
axially and radially outwardly from the respective ends 440 and 442
and terminate in an apex 448 spaced apart from the intermediate
portion 422.
[0082] In the example in FIG. 13, each triangular projection 444
has a width that approximates the width of an elongated triangle
formed of a pair of adjacent elongated features 428 of the
intermediate portion 422. Each projection can have an axial length
that is quite less than intermediate portion. Adjacent triangular
projections 444 are coupled together at the ends 424 and 426 by
additional biasing elements 450. The apex 448 also includes a
similar biasing element 452, which further tends to urge respective
legs 446 apart from each other. Thus, the biasing elements 450 and
452 of the triangular projections cooperate with the biasing
elements 430 of the intermediate portion to increase the associated
radially expansive force of the support 420. As mentioned, however,
the dimensions of the retaining feature 432 can limit the radial
expansion of the support 420. The projections 444 also provide a
mechanism that can engage adjacent tissue, such as when implanted
in a patient's heart, so as to inhibit axial movement of the
prosthesis relative to the heart. Each of the members 440, 442 and
the intermediate portion 422 can be formed from a separate length
of a generally resilient wire that connected together at the ends
by the associated connecting elements 432, as shown in FIG. 13.
While six symmetrical triangular projections are illustrated in
FIG. 13, it is to be appreciated that other numbers and shapes of
projections could be used in accordance with an aspect of the
present invention.
[0083] FIGS. 14 and 15 illustrate an example of a heart valve
prosthesis 470 in accordance with an aspect of the present
invention. The prosthesis 470 is particularly useful during a
direct vision implantation, which can be sutureless, in accordance
with an aspect of the present invention. The prosthesis 470
includes a heart valve 472 mounted within a support, such as the
support 420 of FIG. 13, which can expand from a reduced
cross-sectional dimension to an expanded condition as shown.
Identical reference numbers refer to parts of the support 420
previously identified with respect to FIG. 13. It is to be
understood and appreciated that other deformable, self-expanding
supports also can be utilized in accordance with an aspect of the
present invention.
[0084] The valve 472 includes an inflow end 474 and an outflow end
476 at axially opposed ends of the valve, with a sidewall portion
478 extending between the ends thereof. The inflow end 474 of the
valve 472 is positioned near an inflow end 426 of the support 420.
The sidewall portion 478 can be a tubular valve wall. A plurality
of leaflets 480 extend radially inward from the valve wall 478 and
coapt along their side edges to provide for substantially
unidirectional flow of blood through the valve 472. The outflow end
476 of the valve 472, which is located near the outflow end 424,
has a generally sinusoidal contour. The peaks are aligned with
commissures between adjacent leaflets 480, with sinuses located
between the commissures. The valve 472 can be connected within the
support 420 via sutures 124 or other connecting means.
[0085] By way of illustration, when the prosthesis is to be
implanted at the pulmonary position, the valve 472 can be a treated
porcine pulmonic valve. When it is to be implanted at an aortic
position, the valve 472 can be a porcine aortic valve. For example,
the valve can be of the type shown and described in U.S. Pat. Nos.
5,935,163, 5861,028 or 5,855,602. It is to be understood and
appreciated that other valve configurations of could be used in
accordance with an aspect of the present invention. For example,
one or more leaflets of the valve 472 could be mounted within a
length of tubular valve wall or other generally cylindrical
biocompatible material and operate in a known manner to provide for
the unidirectional flow of fluid through the valve from the inflow
to outflow ends.
[0086] In accordance with an aspect of the present invention, the
prosthesis 470 also includes an outer sheath 482 of a substantially
biocompatible material. The outer sheath 474 covers at least a
substantial amount of exposed portions of the support 420
(including the ends 424 and 426) so as to mitigate contact between
the blood and the support when the prosthesis is implanted. In the
example of FIGS. 14 and 15, the outer sheath 482 covers the entire
support, including the end portions 440 and 442 as well as the
intermediate portion 422. The outer sheath 482, for example, is
formed of one or more natural tissue sheets (e.g., animal
pericardium), although other natural or synthetic biocompatible
materials also could be used to provide an outer sheath in
accordance with an aspect of the present invention.
[0087] FIG. 16 illustrates another example of an elongated
generally cylindrical support 500 that can be employed to support a
heart valve in accordance with an aspect of the present invention.
The support 500 generally consists of two cylindrical support
portions 502 and 504, similar to the support of FIG. 12. The
support portions 502 and 504 are connected together end-to-end in a
substantially coaxial arrangement. For example, a length of a
flexible cord 506 or other flexible retaining element connects
adjacent ends of the respective support portions 502 and 504. The
cord 506 has ends that are connected together to form a loop that
determines a maximum diameter of the support 500 at the juncture
between the two support portions 502 and 504. Other similar loops
of flexible cords 508 and 510 are connected at opposite ends of the
support 500 to inhibit expansion of the ends beyond a desired
maximum diameter. The length of the cords 508 and 510 at the
respective ends can be different so that one end (e.g., the inflow
end) has a greater diameter than the other end (e.g., the outflow
end).
[0088] The support 500 includes a plurality of generally axially
extending features 512 (e.g., resilient rods or wires) that are
biased to urge adjacent interconnected features circumferentially
apart from each other. Because a plurality of such features are
interconnected in a cylindrical arrangement, the biasing of the
features apart from each other results in radially outward
expansion of the cylindrical support 500 according to the
dimensions of the retaining cords 506, 508, and 510. In one aspect,
biasing elements 514, which can be springs, connect each adjacent
pairs of features 512 together at each end of each respective
support portion 502 and 504. Each of the cords 506, 508, 510
further interconnect a respective set of biasing elements at a
corresponding axial location, with the cord 506 interconnecting
biasing elements of both support portions at the intermediate axial
location. While substantially identical biasing elements 514 are
illustrating throughout the support 500, it is to be understood and
appreciated that different types of biasing elements could be used
at different locations of the support. Additionally, a separate
length of a flexible cord can be used to interconnect adjacent
support features, instead of the single loop inserted through an
aperture of the respective biasing elements shown and described
herein.
[0089] In view of the arrangement described above, it is to be
appreciated that a length of the cord 506, 508 or 510 that extends
between adjacent biasing elements 514 of each support portion 502,
504 and the pair of interconnected adjacent features 512 define a
generally triangular structure. A plurality of such triangular
structures are interconnected in a circumferential arrangement to
define the generally cylindrical sidewalls of the respective
support portions 502 and 504. The features 512 of each such
triangular structure are urged apart from each other by the
interconnecting biasing element 514. The juncture of the support
portions 502 and 504 are connected by the connecting element 506 so
as to provide radial expansion combined from both of the support
portions. As a result, about twice the amount of radial expansive
force is provided along the length of the cord 506.
[0090] The resulting support 500 thus provides a cage-like
structure in which a valve can be mounted in accordance with an
aspect of the present invention. The support 500 can be deformed to
a reduced cross-sectional dimension, such as by applying a radially
inward force to the sidewall portion thereof. Upon removal of the
radially inward force, the support will expand to its expanded
cross-sectional configuration due to the radial expansion provided
by the arrangement of biasing elements 514 and interconnected
axially extending features 512.
[0091] In accordance with an aspect of the present invention, FIG.
17 illustrates an example of a heart valve prosthesis 540 that
includes a valve 542 mounted within a support 500, such as shown
and described with respect to FIG. 16. Identical reference numbers
refer to parts previously identified with respect to the support
500 of FIG. 16. The valve 542 has an inflow end 544 and an outflow
end 546, which are positioned on axially opposed sides of the
intermediate cord 506. In particular, the cord 506 and associated
biasing elements 514 substantially circumscribe an annular base
portion 548 of the valve 542 and help maintain it in a desired
annular shape when the prosthesis 540 is in its expanded condition,
as shown in FIG. 17.
[0092] The valve 542 illustrated in FIG. 17 includes three leaflets
that extend radially inwardly from a length of trimmed valve wall
so as to coapt and provide for the unidirectional flow of blood
through the prosthesis from the inflow end 544 to the outflow end
546. The outflow end 546 has a generally sinusoidal contour, with
peaks at the commissures between adjacent leaflets and sinuses
between commissures extending an arc length commensurate with the
arc length of the associated leaflet.
[0093] By way of illustration, when the prosthesis 540 is to be
implanted at the pulmonary position, the valve 542 could be a
treated porcine pulmonic valve and a porcine aortic valve when it
is to be implanted at an aortic position. For example, the valve
can be of the type shown and described in U.S. Pat. Nos. 5,935,163,
5861,028 or 5,855,602. Of course, other types and valve
configurations also could be used in combination with the support
500 to form the prosthesis 540 in accordance with an aspect of the
present invention.
[0094] The prosthesis 540 further includes an outer sheath 550 of a
flexible biocompatible material, such as treated and detoxified
animal pericardium, as described herein. The outer sheath 550
covers at least some of the exposed support 500, such as the
interior of the prosthesis and the ends 552 and 554. The outer
sheath 550 can be formed of one or more sheets of the biocompatible
material, which are attached to the prosthesis 540 to reduce
exposure of the support to blood when implanted in its expanded
condition. The outer sheath 550 is sufficiently flexible and
resilient so as to facilitate deforming the prosthesis 540 to a
reduced cross-sectional dimension and its subsequent expansion to
its expanded cross-sectional dimension, as shown in FIG. 17.
[0095] The sidewall portion of the valve 542 is attached (e.g., by
sutures) to the support 500, such as to features and/or biasing
elements, so that when the support expands, the valve also expands
to its desired expanded configuration. Also, because the valve 542
has been fixed (e.g., in a suitable glutaraldehyde solution) to a
desired shape and configuration, the valve maintains its desired
shape and coaptation between leaflets when the prosthesis 540 is in
its expanded condition.
[0096] Prior to implanting the 540, such as by a direct
implantation procedure through a blood vessel that provides a
generally linear path to the desired implantation site, one or more
sutures 554 can be attached to the proximal end 552 of the
prosthesis. For example, the suture 554 is applied through loops
that form generally diametrically opposed biasing elements 514 at
the proximal end 552. The sutures 554 can be used to adjust the
relative position of the prosthesis 540 after positioned in the
heart in its expanded condition. Additionally or alternatively, the
prosthesis 540 could be adjusted to a desired position manually by
a surgeon by applying external force to the prosthesis through the
heart. Advantageously, the prosthesis 540 can be directly implanted
without cardiopulmonary bypass, such as in the pulmonary position
or with minimal bypass to the aortic position in accordance with an
aspect of the present invention.
[0097] FIG. 18 illustrates another example of a heart valve
prosthesis 570 in accordance with an aspect of the present
invention. The prosthesis 570 is similar to that show and described
with respect to FIG. 17. Briefly stated, the prosthesis 570
includes first and second generally cylindrical portions 572 and
574 that are connected together end to end by an intermediate
flexible connecting element 576 having a desired diameter, such as
a loop of a cord (e.g., suture). The connecting element 576 limits
the radial expansion of an intermediate portion of the prosthesis
to predetermined diameter.
[0098] Each of the cylindrical portions 572 and 574 includes a
plurality of generally axially extending support features 578, such
as thin rods, bands, or wire of a substantially resilient material.
The features 578, for example, are arranged as a plurality of
interconnected triangles in which the features define elongated
legs that extend between the intermediate connecting element 576
and additional connecting elements 580 and 582 located at the
opposite ends 584 and 586 of the associated cylindrical portions
572 and 574. The connecting element 582 at the inflow end of the
valve also can have a greater diameter than the connecting element
580 at the outflow end. The features 578 in each cylindrical
portion 572 and 574 are connected by biasing elements 588 that urge
each adjacent pair of interconnected features circumferentially
apart from each other. Because the features 578 are connected in a
circumferential array, the collective forces of the biasing
elements result in radially outward expansion of the prosthesis 570
up to a maximum dimension defined by the respective connecting
elements 576, 580 and 582.
[0099] The prosthesis 570 further includes a heart valve 590
mounted within the support. The valve 590 has an inflow end 592 and
an outflow end 594, which are positioned on axially opposed sides
of the intermediate cord 576. In particular, the intermediate
connecting element 576 and associated biasing elements 588
substantially circumscribe an annular base portion near the inflow
end 592 of the valve 590. Because the valve 590 is attached (e.g.,
by sutures) to the support formed of the cylindrical portions 572
and 574, the radial outward forces provided by the support help
maintain the base of valve in a desired annular shape when the
prosthesis 570 is in its expanded condition shown in FIG. 18. When
the inflow end of the valve 590 is in its desired annular shape,
the leaflets of the valve also are in desired orientation to
provide desired coaptation between the leaflets, which facilitates
the unidirectional flow of blood through the valve.
[0100] By way of example, when the prosthesis 570 is to be
implanted at the pulmonary position, the valve 590 could be a
treated porcine pulmonic valve. A porcine aortic valve can be used
for the aortic position. Those skilled in the art will understand
and appreciate other types and valve configurations also could be
used in the prosthesis 570 in accordance with an aspect of the
present invention.
[0101] The prosthesis 570 further includes an arrangement of
members 598 and 600 that extend axially and radially outwardly from
the respective ends 584 and 586 of the prosthesis 570. The members
598 and 600 are operative to help secure the prosthesis 570 to
surrounding tissue when it is implanted. The members 598 and 600
include a plurality of triangular projections 602 that extend
axially and radially outwardly from the ends. While six
substantially symmetrical projections are shown extending outwardly
from each of the ends 584 and 586, those skilled in the art will
understand and appreciate that any number could be used (e.g., 4,
6, 9, 12, 18, etc.).
[0102] Each triangular projection 602 includes a pair of legs 604
that are connected together by an interconnecting biasing element
606. The biasing elements form apices of the triangular projection
602 spaced from the respective ends 584, 586. Adjacent triangular
projections 602 also are coupled together and to respective ends
584 and 586 by additional biasing elements 608 located at the ends
of the prosthesis 570. The biasing elements 588, 606, and 608 bias
the support portion of the prosthesis 570 and valve 590 attached
thereto in a radially outward direction toward its fully expanded
condition. Additionally, the triangular projections 602 can further
engage surrounding tissue when the prosthesis is implanted to help
hold the prosthesis at a desired position relative to the
surrounding tissue.
[0103] The prosthesis 570 also can include an outer sheath 610 of
biocompatible material (e.g., animal pericardium) that covers most
(or all) of the support structure that would be exposed to blood
when implanted. The covering further could be an expansion of the
valve wall the contains the leaflets of the heart valve 590. In
this example, the outer sheath 610 covers the support between the
ends 584 and 586 of the cylindrical portions 572 and 574 and the
support features 578 in the interior of the prosthesis 570. The
triangular projections 602 are left uncovered, which may facilitate
their insertion and integration into surrounding tissue. It is to
be understood and appreciated, however, that the projections 602
also could be covered with biocompatible material, similar to the
example of FIGS. 14 and 15.
[0104] The prosthesis 570 is well suited for direct implantation
without cardiopulmonary bypass, such as in the pulmonary position,
or direct implantation with minimal bypass to the aortic position
in accordance with an aspect of the present invention. Direct
implantation with the prosthesis also can be sutureless, although
one or more sutures can be applied to further fix the prosthesis at
a desired position.
[0105] In view of the various arrangements of heart valve
prostheses described herein, a simplified and efficient method of
using such prosthesis is described below with respect to FIGS.
19-22. The prosthesis can be directly implanted into the patient's
heart in an efficient and low-invasive procedure, which also can be
sutureless. While the particular example utilizes a heart valve
prosthesis similar to that shown and described in FIG. 18, it is to
be understood and appreciated that any of the prosthesis (see,
e.g., FIGS. 1-18) described herein, could be implanted in a similar
manner.
[0106] FIGS. 19 and 20 illustrates an implanter apparatus 700 for
implanting a heart valve prosthesis 702 in accordance with an
aspect of the present invention, such as to facilitate sutureless
implantation under direct vision of the surgeon. The implanter 700
includes an elongated cylindrical barrel 704 that extends from a
body portion 706 and terminates in an open end 708. The barrel 704
has an inner diameter that is less than the outer diameter of the
heart valve prosthesis 702 in its expanded condition. Thus, in
order to facilitate insertion of the prosthesis 702 into the barrel
704, the prosthesis should be deformed to a reduced cross-sectional
dimension, such as at about one-half or less of its fully expanded
condition, as shown in the enlarged view of FIG. 20.
[0107] For example, the inner diameter of the barrel 704 can range
from about 5 mm to about 15 mm, whereas the outer diameter of the
heart valve prosthesis 702 (in its expanded condition) typically
ranges from about 15 mm to about 35 mm. Thus, the barrel can
accommodate a prosthesis 702, which has been deformed to reduced
cross-sectional dimension, without compromising the durability and
operation of the valve. The exterior of the barrel further can
include indicia (e.g., ruler markings) 710 that can help indicate
the distance the barrel is inserted into a patient.
[0108] Additionally, to facilitate positioning the end 708 of the
barrel 704 at a desired position, such as in a patient's heart, the
barrel 704 (or at least a distal end portion thereof) can be formed
of a flexible, generally resilient material (e.g., a metal or
plastic material) that can bend or flex relative to its
longitudinal axis A, as indicated at 704'. By way of particular
example, the barrel 704 can be formed of helical extension spring,
such as formed of a thin wire tightly wound to defines the circular
cylindrical barrel in which the heart valve prosthesis can be
loaded for implantation. The barrel 704 thus can flex to a curved
or bent position 704', such as to accommodate different angular
contours that might be experienced in various passages in the
patient's heart as the barrel 704 is guided to a desired
implantation position. Such compliant tensile properties of the
barrel 704, for example, facilitate gently deflecting the barrel
off anatomical structures during implantation, such as the barrel
is advanced to its implantation position.
[0109] Alternatively or additionally, the barrel 704 can be formed
of a deformable material, such as synthetic material (e.g., a
polymer) or a metal, that can be deformed to provide a desired
curved barrel 704' for supporting the heart valve prosthesis 702'
for implantation. Accordingly, the barrel 70 can be curved or bent
relative to the longitudinal axis A of the implanter 700, as
indicated at 704'. For example, Those skilled in the art will
understand and appreciate various suitable materials that could be
utilized to provide desired flexible and/or deformable
properties.
[0110] The implanter 700 also includes a handle 712 that extends
outwardly from a proximal end 714 of the body portion 706. The
handle 712, which may be gripped by a surgeon, facilitates
manipulating the barrel 704 along a desired path. A plunger 716 has
a distal end 718 that can be urged into engagement with the
prosthesis 702 to push the prosthesis from the opening 708 of the
barrel 704. The plunger 716 includes an elongated portion that
extends from its distal end 718 and terminates in a proximal end
portion 718. The proximal end portion 718 operates as a trigger
that can be grasped by a surgeon to move the plunger through the
barrel 704. Other means to discharge the heart valve also could be
utilized in accordance with an aspect of the present invention.
Fluid, such as saline, also can be introduced into the barrel 704,
such as through an opening (not shown) in the plunger 716, to
facilitate the discharge of the prosthesis 702 from the barrel.
[0111] In the examples of FIGS. 19 and 20, the heart valve
prosthesis 702 is positioned within the barrel 704 with its inflow
end 720 adjacent to the outflow end, such as for implanting the
valve in a pulmonary position. Those skilled in the art will
understand and appreciate that the outflow end 722 of the valve 702
alternatively could be positioned adjacent the opening 708 of the
barrel. The particular orientation of the valve 702 within the
barrel 704 will depend on where the valve is being implanted and
the direction from which the implanter 700 is being inserted
relative to the implant site. In accordance with a particular
aspect of the present invention, the implanter 700 and heart valve
prosthesis 702 is particularly useful for an open chest procedure
in which the prosthesis is introduced into the heart under
substantially direct vision of the surgeon.
[0112] For example, the implanter 700 could be introduced into a
blood vessel (e.g., the pulmonary artery) that provides a
substantially direct and linear path to the desired implantation
position. Further, the procedure can be implemented without
cardiopulmonary bypass, such as when the prosthesis is implanted
through the pulmonary artery. Alternatively, cardiopulmonary bypass
can be used, but for a generally short period of time, such as when
the prosthesis is implanted at the aortic position. Bypass
generally is required when implanting at the aortic position due to
the relatively high blood pressure as well as to facilitate
decalcification of the patient's existing heart valve, as
needed.
[0113] The implanter 700 further can include an aperture 724 (or
interconnected apertures) that extend longitudinally through the
plunger 716 and the end 718. The aperture 724 provides a passage
through which one or more sutures 726 connected to a proximal end
728 of the prosthesis 702 can extend. For example, prior to loading
the prosthesis 702 into the barrel 704, the suture 726 can be
applied to the end 728 of the prosthesis, such as through generally
diametrically opposed biasing elements (e.g., coil springs) at the
respective end. Part of the suture 726 extends between the opposed
sides of the prosthesis 702. The remaining lengths of the suture
726, which extends from one or both sides of the prosthesis, can be
fed through the barrel and aperture 724 to a location external to
the implanter 700, such as shown in FIG. 19. The suture 726 should
have a sufficient length to extend through the implanter 700, as
shown. After the prosthesis 702 has been discharged from the
implanter, the suture 726 then can be grasped by a surgeon to
adjust the position of the prosthesis.
[0114] FIG. 21 illustrates an intermediate part of an implantation
procedure in accordance with an aspect of the present invention. In
this example, cardiopulmonary bypass is not required, as blood loss
is mitigated through application of a purse string suture. For
example, after the patient's chest is opened, a purse string suture
730 is applied to the pulmonary artery or other vessel 732 through
which a barrel 734 of an implanter 736 is to be inserted. A small
incision or puncture is made at the center of the purse string 730,
which should approximate or be slightly smaller than the outer
diameter of the barrel. Alternatively, the incision could be made
prior to application of the purse string to the vessel wall.
[0115] The surgeon can then insert the barrel 734 through the
opening in the vessel wall 732. Two lengths 738 of the purse string
730 suture extend from the vessel 732 through an elongated
cylindrical guide 740 of a generally rigid material, such as
rubber, plastic, or metal material. One end 742 of the cylinder 740
engages the vessel wall 732 and/or the barrel 734, and the two
lengths 738 of suture extend through the other end 744. By fixing
the length of suture relative to the cylinder 740, such as by
clamping the sutures to the cylinder by a clamp 745, the vessel
wall surrounding the barrel 734 can be kept relatively tight around
the barrel so as to mitigate blood loss through the incision. As a
result, cardiopulmonary bypass is not required. However, it is to
be understood that in certain situations, such as when implanting
the prosthesis at the aortic position, some bypass may be
necessary, although usually for a much shorter period of time than
with conventional procedures.
[0116] After the distal end 746 of the barrel 734, which can be
flexible or bendable as described herein, has been inserted a
desired length into the vessel 732, such as indicated by indicia
printed on the barrel, the heart valve prosthesis 748 located in
the barrel can be discharged. For example, a plunger 750 positioned
for axial movement relative to the barrel 734 can be moved toward
the distal end 746 of the barrel and into engagement with the
prosthesis 748. The heart valve prosthesis 748 is configured to
expand toward its fully expanded condition when it is discharged
from the barrel 734 because radial inward forces that maintain the
prosthesis at a reduced cross-sectional dimension are removed. In
particular, the prosthesis 748 includes a self-expanding support
752 in which an associated heart valve 754 is mounted. In the
example of FIG. 21, the support 752 and valve 754 are configured as
shown and described in FIG. 18. That is, the support 752 includes a
cage-like frame of axially extending resilient support features 756
interconnected by biasing elements 758 that urge the support in a
radially outward direction. Generally triangular projections 760,
which also are biased radially outwardly, further extend from the
ends of the support 752. The triangular projections 760 operate to
engage the surrounding valve wall (or other surrounding tissue)
when the support expands so as to anchor the prosthesis 748
relative to the valve wall. As the prosthesis 748 is being
discharged, the implanter barrel 734 can be concurrently withdrawn
from the vessel to help ensure that the prosthesis is positioned at
the desired position.
[0117] One or more sutures 762 can be attached to a proximal end
764 of the prosthesis 748 so as to pass through an aperture 766
that extends through at least a substantial portion of the
implanter 736. For example, the suture 762 can be applied through
the centers of generally opposed circular biasing elements located
at the proximal end 764. After the prosthesis 748 is discharged
into the patient's heart, a surgeon can grasp the sutures to adjust
the position of the prosthesis, such as by urging both ends of the
suture in the direction 768, shown in FIG. 21. Additionally or
alternatively, the relative position of the discharged prosthesis
748 can be adjusted through the heart or blood vessel manually or
by employing other tools. Once the prosthesis 748 is at a desired
position, one end of the suture can be pulled so as to remove the
suture from the prosthesis. The adjustments can be performed with
part of the implanter 736 still within the blood vessel 732 or
after the implanter has been removed from the vessel.
[0118] FIG. 22 illustrates the heart valve prosthesis 748 mounted
at a pulmonary position after the implanter 736 has been removed
from the pulmonary artery 732 through which the prosthesis 748 was
implanted in accordance with an aspect of the present invention. As
described herein, the barrel 734 can be generally rigid, flexible
or deformable, such as part of a catheter or other type of
implanter. After the barrel 734 of the implanter 736 has been
withdrawn from the pulmonary artery 732, the purse string 730
facilitates closure of the incision. For example, the guide 740
(FIG. 21) can be held against the pulmonary artery 732 while
concurrently pulling additional length of the suture 738 through
the cylinder 740 and then tying off the purse string at the
pulmonary artery. Additional sutures can be applied to the incision
site to ensure proper closure. With the projections 760 engaging
surrounding tissue and the outward force of the support 752, the
prosthesis 748 should be adequately anchored at the desired
position. Although, to help ensure that the prosthesis remains at
the desired position, one or more sutures also can be applied to
the prosthesis, such as directly through the heart muscle itself.
The support 752 further helps maintain desired coaptation between
the leaflets by urging the inflow end of the valve toward a desired
annular shape.
[0119] In view of the foregoing example, those skilled in the art
will understand and appreciate that the prosthesis 748 can be
implanted without opening the heart and without cardiopulmonary
bypass. When the patient's existing valve needs to be removed and
or calcium deposits cleaned, such cleaning can be performed through
the pulmonary artery or other connecting vessels prior to
implanting the prosthesis 748, such as through a trocar and/or by
endoscopic means.
[0120] FIG. 23 depicts an example of a valvular prosthesis 800
being implanted in a patient's heart 802 at an aortic position
according to an aspect of the present invention. When being
implanted at an aortic position, an aortic valve (e.g., equine,
porcine, bovine, etc.) can be utilized for the valve portion of the
prosthesis, although other types of valve portions also could be
used. Prior to implanting the prosthesis 800, the patient's own
aortic valve or at least calcified portions thereof should be
removed.
[0121] In this example, the prosthesis 800 is being implanted
through the patient's aorta 804. The prosthesis includes an include
an inflow end 806 that is positioned at the aortic annulus 807,
with an outflow end 808 of the prosthesis extending into the aorta
804. As described herein, the implantation can be sutureless since
the prosthesis 800 includes spikes or other projections 810 that
extend outwardly from the prosthesis. Such spikes or protrusions
810 thus engage surrounding tissue, such as the aortic valve wall
804, for inhibiting axial and rotational movement of the implanted
prosthesis 800, as described herein.
[0122] In the example of FIG. 23, the prosthesis 800 is implanted
at the aortic position from the barrel 812 of an implanter. The
implanter can be a catheter type of implanter in which the barrel
is dimensioned to retain the prosthesis in a compressed condition
during insertion through the aorta 804 After the distal end of the
barrel is at a desired position, the valvular prosthesis 800 is
discharged to its expanded condition. The barrel 812 can be
flexible, deformable or generally rigid, as described herein.
[0123] It is to be appreciated that the valvular prosthesis 800 may
be implanted in the aortic position during a conventional open
chest procedure or during a closed chest procedure. In the example
of FIG. 23, the barrel 812 can be urged through a small incision
made in the aorta 804. Because the only incision is in the
patient's aorta, the implantation can be performed during very
short open chest surgery, for example, with reduced cardiopulmonary
bypass when compared to conventional procedures.
[0124] The implantation can be performed in a manner similar to
that described above with respect to FIG. 21. For example, after
the patient's chest is opened, a purse string suture 814 is applied
to the aorta 804, through which a small incision or puncture is
made for inserting the barrel 812. Ends 816 of the purse string 814
are inserted through a hollow guide element 818. A distal end 820
of the guide element 818 is urged against the aorta 804 and the
barrel 812, and a proximal end 822 is extended away from the heart
802. The ends 816 of the purse string suture are pulled through the
guide element 818 and can be fixed relative to the guide, such as
by clamping the sutures to the guide with a clamp 824. As a result,
the vessel wall surrounding the barrel 812 can be kept relatively
tight around the barrel so as to mitigate blood loss through the
incision during the procedure. As a result, cardiopulmonary bypass
can be kept at a minimum with little blood loss.
[0125] It is to be understood and appreciated, though, if the
patient has a calcified aortic valve, the patient typically must be
put on cardiopulmonary bypass to remove the calcium and implant the
valve. Advantageously, a valvular prosthesis 800 in accordance with
the present invention may be implanted more efficiently so as to
mitigate morbidity and mortality of the patient. In addition, the
prosthesis 800 can be implanted without sutures (or, alternatively,
some sutures can be utilized. For example, optional sutures (not
shown) may be applied near the inflow end 806 and/or at the outflow
end 808, such as when the prosthesis is configured to have axially
extending lobes (see, e.g., FIG. 8).
[0126] FIG. 24 illustrates an alternative approach for implanting a
heart valve prosthesis 850 at the pulmonic position in a patient's
heart 852 in accordance with an aspect of the present invention. As
described herein, the prosthesis 850 includes a valve portion 854
having an inflow end 856 and an outflow end 858 spaced therefrom.
The valve portion 854 can be a natural tissue heart valve, such as
a homograft or xenograft, although other types of natural tissue
heart valves also could be utilized, such as described herein. The
valve portion 854 is mounted within a support or stent 860, such as
one of the types described herein. The support 860 includes spikes
or protruding portions 862 for engaging surrounding tissue of the
pulmonary artery 864 in its implanted position. The protruding
portions 862 thus inhibit axial and/or angular movement of the
implanted prosthesis 850.
[0127] In this example, the prosthesis 850 is implanted into the
pulmonary artery 864 from a barrel 866 of an implanter, such as a
catheter system or other type of implanter described herein. In
particular, a distal end 868 of the barrel is inserted through the
heart muscle itself, such as through the anterior wall 870 of the
right ventricle 872. Once at the desired position, the prosthesis
850 is ejected from the barrel 866 into the outflow of the right
ventricle 872, as illustrated in FIG. 24. By entering through the
anterior wall 870, a substantially direct or generally linear
implantation can be performed with little or no cardiopulmonary
bypass. Those skilled in the art will understand and appreciate
other possible paths through the heart that could be employed for
positioning the distal end 868 of the barrel 866 to facilitate
sutureless implantation of a heart valve prosthesis in accordance
with an aspect of the present invention.
[0128] FIG. 25 depicts an example of another type of support
structure 900 that could be used to support a heart valve to
provide a prosthesis in accordance with an aspect of the present
invention. The support 900 includes axially spaced apart ends 902
and 904 interconnected by generally axially extending support
features 906. In the example of FIG. 25, adjacent support features
906 are interconnected by arcuate junctures 908 and 910 at the
respective ends 902 and 904 so as to define a generally sinusoidal
sidewall portion 912 arranged in a generally cylindrical
configuration. In the example of FIG. 25, there are six junctures
908 and 910 at each of the respective ends 902 and 904 that are
interconnected by associated support features 906. Those skilled in
the art will understand and appreciate that other numbers (e.g., 2,
3, 9, 12 and so forth) and configurations of end junctures 908, 910
can be utilized in accordance with an aspect of the present
invention. For example, as an alternative to curved interconnecting
end junctures 908, 910 shown in FIG. 25, such ends could be pointed
or rectangular.
[0129] The support 900 further includes one or more projections or
spikes 914 that extend axially and radially outwardly from at least
some of the respective end junctures 908, 910 of the support. While
a pair of such spikes are illustrated as associated with each end
juncture 908, 910, other number of spikes can be implemented, such
as single spike or more than two spikes at some or all of the
junctures. In the example illustrated in FIG. 25 the pairs of
spikes at opposite ends operate to mitigate movement in different
directions, such as by having each spike 914 forming an acute angle
relative to its associated support feature 906 from which it
extends.
[0130] According to one aspect of the present invention, the
support can be formed a shape memory material, such as nitinol. For
example, the support can be formed from a small cylindrical tube of
the shape memory material, such as via a laser cutting (ablation)
process in which the desired sinusoidal sidewall 912 is cut from
the tube. In this way, the support features 906, the
interconnecting end junctures 908 and 910, and associated spikes
914 can be formed as an integrated structure having a desired shape
and size. Additionally, ends of the spikes 914 can have tapered or
sharpened tips to facilitate gripping surrounding tissue when
implanted. For example, the spikes 914 can be formed by laser
cutting from the same tube or, alternatively, they could be welded
onto the support 900 at desired positions. The resulting structure
can then be heated to its transformation temperature and forced to
a desired cross-sectional dimension and configuration (its
austentic form), such as shown in FIG. 25. The support 900 can then
be bent or deformed to a reduced cross-sectional dimension when in
its low-temperature (martensitic) form to facilitate its mounting
within a barrel of a implanter, for example.
[0131] FIG. 26 illustrates an example of a heart valve prosthesis
918 in accordance with an aspect of the present invention. The
prosthesis 918 can be implanted during a direct vision
implantation, which can be sutureless, in accordance with an aspect
of the present invention. The prosthesis 918 includes a heart valve
920 mounted within a support, such as the support 900 of FIG. 25,
which can expand from a reduced cross-sectional dimension to an
expanded condition as described herein. Identical reference numbers
refer to parts of the support 900 previously identified with
respect to FIG. 25. It is to be understood and appreciated that
other deformable, self-expanding supports also can be utilized in
accordance with an aspect of the present invention.
[0132] The valve 920, which can be a homograft or xenograft,
includes an inflow end 922 and an outflow end 924 at axially
opposed ends of the valve, with a sidewall portion extending
between the ends thereof. The inflow end 922 of the valve 920 is
positioned near an inflow end 904 of the support 900. The
prosthesis 920 also can include sidewall portion, which can be a
tubular valve wall, such as for a homograft or xenograft valve 920.
A plurality of leaflets 926 extend radially inward from the valve
wall and coapt along their adjacent edges to provide for
substantially unidirectional flow of blood through the valve 920.
The outflow end 924 of the valve 920, which is located near the
outflow end 902 of the support, has a generally sinusoidal contour,
as shown in FIG. 26. The peaks of the sinusoidal outflow end 924
can be aligned generally with and attached to support junctures 908
at the end 902 of the support 900. The valve 920 can be connected
within the support 900 via sutures or other known connecting means,
for example.
[0133] It is to be understood and appreciated that various types of
valve configurations of could be employed to provide the prosthesis
918 in accordance with an aspect of the present invention. For
example, the valve 920 can include one or more leaflets mounted
within a length of tubular valve wall or other generally
cylindrical biocompatible material and operate in a known manner to
provide for the unidirectional flow of fluid through the valve from
the inflow to outflow ends. By way of further example, when the
prosthesis is to be implanted at the pulmonary position, the valve
920 can be a treated pulmonic valve (e.g., homograft or xenograft).
When it is to be implanted at an aortic position, the valve 920 can
be a treated aortic valve (e.g., homograft or xenograft). For
example, the valve can be of the type shown and described in U.S.
Pat. Nos. 5,935,163, 5861,028 or 5,855,602, as well as others
mentioned herein or otherwise known in the art.
[0134] In accordance with an aspect of the present invention, the
prosthesis 918 also includes an outer sheath 930 of a substantially
biocompatible material. The outer sheath 930 covers at least a
substantial amount of exposed portions of the support 900, such as
including the ends 902 and 904, to mitigate contact between the
blood and the support when the prosthesis is implanted. The valve
920 further can be attached relative to the sheath 930, such as by
sutures along the inflow and outflow ends of the valve. Such
sutures (not shown) further can connect the valve 920 and the
sheath 930 relative to the support 900. The outer sheath 930 can
cover the entire support, such that all non-biological material is
completely covered, for example. The outer sheath 930 can be formed
of one or more natural tissue sheets (e.g., animal pericardium),
although other natural or synthetic biocompatible materials also
could be used to provide an outer sheath in accordance with an
aspect of the present invention.
[0135] FIG. 27 depicts an example of sutureless implantation of a
heart valve prosthesis 950 being implemented in accordance with an
aspect of the present invention. In this example, the prosthesis is
illustrated of the type shown and described with respect to FIGS.
25 and 26. It will be appreciated that valve can be implanted
within a vessel wall or other implantation site 952 without
cardiopulmonary bypass or at least reduced bypass when compared to
traditional approaches. The prosthesis 950 includes inflow and
outflow ends 954 and 956 and a valve portion 958 mounted within a
support 960 located between ends thereof. The support 960 includes
spikes or protruding members extending outwardly from ends of the
support. The spikes and support can be formed from an integral
piece of a metal or alloy, such as nitinol, for example. A sheath
964 of biocompatible biological tissue (e.g., animal pericardium)
covers at least a portion of the support to mitigate contact
between fluid and non-biological portions of the prosthesis.
[0136] The implantation of the prosthesis 950 can be implemented in
a manner similar to that show and described with respect to FIG.
21. Briefly stated, the prosthesis is ejected from a barrel 966 by
a plunger 968 that is moveable axially within the barrel. To
facilitate positioning the prosthesis 950 at a desired implantation
site, the barrel 966 can be flexible, such as described herein, so
as to gently deflect in response to contacting tissue along the
passage toward to implantation site 952. Alternatively, the barrel
can be deformable or generally rigid.
[0137] A small incision or puncture can be made at the center of a
purse string 970 that is applied around the location through which
the barrel 966 is to be inserted. The surgeon can then insert the
barrel 966 through the opening in the vessel wall 952. Two ends 972
of the purse string 970 suture extend from the vessel wall or other
tissue and through an elongated hollow guide 974. A distal end 976
of the guide 974 engages the vessel wall 952 and/or the barrel 966,
and the two ends 972 extend through the other end 978. The suture
can be fixed relative to the guide 974, such as by clamping the
sutures to the cylinder by a clamp 980. As a result, the vessel
wall (or other tissue) surrounding the barrel 966 can be kept
relatively tight around the barrel to mitigate blood loss.
Consequently, cardiopulmonary bypass is not required. However, it
is to be understood that in certain situations, such as when
implanting the prosthesis at the aortic position, some bypass may
be necessary, although usually for a much shorter period of time
than with conventional procedures.
[0138] As mentioned above, the prosthesis 950 includes a
self-expanding support 960. Thus, the heart valve prosthesis 950
can expands toward its fully expanded condition when it is
discharged from the barrel 966. The projections or spikes 962, in
turn, will insert into surrounding tissue to maintain the valve at
a desired axial and angular position in the vessel 952, thereby
anchoring the prosthesis 950 relative to the valve wall. As the
prosthesis 950 is being discharged, the implanter barrel 966 can be
concurrently withdrawn from the vessel. While the implantation can
be performed completely sutureless, those skilled in the art will
understand and appreciate that one or more sutures can be utilized
to further help secure the prosthesis 950 relative to the
surrounding tissue 952.
[0139] What has been described above includes examples of the
present invention. It is, of course, not possible to describe every
conceivable combination of components or methodologies for purposes
of describing the present invention, but one of ordinary skill in
the art will recognize that many further combinations and
permutations of the present invention are possible. Accordingly,
the present invention is intended to embrace all such alterations,
modifications and variations that fall within the spirit and scope
of the appended claims. Furthermore, to the extent that the term
"includes" and variants thereof or the term "having" and variants
thereof are used in either the detailed description or the claims,
each such term is intended to be inclusive in a manner similar to
the term "comprising."
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