U.S. patent application number 15/131753 was filed with the patent office on 2017-11-16 for prosthetic cardiac valve formed from pericardium material and methods of making same.
The applicant listed for this patent is Medtronic, Inc.. Invention is credited to Carol Eberhardt, Janice Shay.
Application Number | 20170325942 15/131753 |
Document ID | / |
Family ID | 38477064 |
Filed Date | 2017-11-16 |
United States Patent
Application |
20170325942 |
Kind Code |
A9 |
Eberhardt; Carol ; et
al. |
November 16, 2017 |
PROSTHETIC CARDIAC VALVE FORMED FROM PERICARDIUM MATERIAL AND
METHODS OF MAKING SAME
Abstract
A prosthetic stented heart valve which includes a compressible
and expandable stent structure having first and second opposite
ends, an expanded outer periphery, and a compressed outer periphery
that is at least slightly smaller than the expanded outer periphery
when subjected to an external radial force. The valve further
includes a valve segment comprising a dual-layer sheet formed into
a generally tubular shape having at least one longitudinally
extending seam, and a plurality of leaflets formed by attachment of
an outer layer of the dual-layer sheet to an inner layer of the
dual-layer sheet in a leaflet defining pattern. The valve segment
is at least partially positioned within the stent structure. The
valve may further include at least one opening in the outer layer
of the dual-layer sheet that is spaced from both the first and
second ends of the stent structure.
Inventors: |
Eberhardt; Carol;
(Fullerton, CA) ; Shay; Janice; (Lake Forest,
CA) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Medtronic, Inc. |
Minneapolis |
MN |
US |
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|
Prior
Publication: |
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Document Identifier |
Publication Date |
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US 20160228245 A1 |
August 11, 2016 |
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Family ID: |
38477064 |
Appl. No.: |
15/131753 |
Filed: |
April 18, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13316885 |
Dec 12, 2011 |
9331328 |
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15131753 |
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11729680 |
Mar 28, 2007 |
8075615 |
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13316885 |
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60786849 |
Mar 28, 2006 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 2/2418 20130101;
A61F 2210/0076 20130101; H01M 10/0566 20130101; H01M 4/131
20130101; Y02E 60/10 20130101; Y02P 70/54 20151101; H01M 4/5825
20130101; H01M 4/485 20130101; H01M 10/0565 20130101; Y02E 60/122
20130101; A61F 2220/0075 20130101; A61F 2/2415 20130101; H01M
10/0525 20130101; Y02P 70/50 20151101; A61F 2230/0054 20130101;
A61F 2310/00011 20130101 |
International
Class: |
A61F 2/24 20060101
A61F002/24; H01M 10/0525 20100101 H01M010/0525; H01M 4/485 20100101
H01M004/485; H01M 10/0566 20100101 H01M010/0566; H01M 4/131
20100101 H01M004/131; A61F 2/24 20060101 A61F002/24; H01M 4/58
20100101 H01M004/58; H01M 10/0565 20100101 H01M010/0565 |
Claims
1-20: (canceled)
21: A prosthetic heart valve comprising: a radially compressible
and expandable tubular metal frame structure having a longitudinal
axis and extending from an inflow edge along the longitudinal axis
to an outflow edge along the longitudinal axis; and a tubular
member comprising a multi-layer portion defining an inflow edge of
the tubular member and a single-layer portion defining an outflow
edge of the tubular member and a pocket portion; wherein the pocket
portion comprises a first material layer of the multi-layer portion
and a second material layer of the multi-layer portion; wherein at
least a portion of the second material layer is secured to at least
a portion of the first material layer; wherein the pocket portion
comprises first and second side edge portions; wherein the pocket
portion comprises an open edge longitudinally spaced from the
inflow edge of the tubular member and extending from the first side
edge portion of the pocket portion to the second side edge portion
of the pocket portion; wherein the second material layer extends
longitudinally from the inflow edge of the tubular member to the
open edge of the pocket portion; wherein the first material layer
extends longitudinally from the inflow edge of the tubular member
beyond the open edge of the pocket portion; wherein at least a
portion of the first material layer is longitudinally positioned
within and attached to the metal frame structure; wherein the
pocket portion comprises an arcuate portion longitudinally spaced
from the inflow edge of the tubular member and having a continuous
arc extending from the first side edge portion of the pocket
portion to the second side edge portion of the pocket portion;
wherein the pocket portion is configured to stop a flow of
blood.
22: The prosthetic heart valve of claim 21, wherein the tubular
member covers the inflow edge of the metal frame structure.
23: The prosthetic heart valve of claim 21, wherein the tubular
member overlaps the inflow edge of the metal frame structure.
24: The prosthetic heart valve of claim 21, wherein the first and
second material layers comprise different materials.
25: The prosthetic heart valve of claim 21, wherein the first and
second material layers comprise the same material.
26: The prosthetic heart valve of claim 21, wherein the prosthetic
heart valve has a one way fluid passage extending from the inflow
edge of the metal frame structure to the outflow edge of the metal
frame structure.
27: The prosthetic heart valve of claim 21, wherein a compressed
outer periphery of the metal frame structure is sized for
percutaneous insertion and implantation in an anatomical structure
of a patient.
28: The prosthetic heart valve of claim 21, wherein the pocket
portion defines a leaflet.
29: The prosthetic heart valve of claim 21, wherein the pocket
portion comprises a plurality of pockets.
30: The prosthetic heart valve of claim 29, wherein the plurality
of pockets are arranged together in a generally tubular shape.
31: The prosthetic heart valve of claim 29, wherein the plurality
of pockets define a plurality of leaflets.
32: The prosthetic heart valve of claim 29, wherein the plurality
of pockets each comprise first and second side edge portions.
33: The prosthetic heart valve of claim 32, wherein the plurality
of pockets each comprise an arcuate portion longitudinally spaced
from the inflow edge of the tubular member and having a continuous
arc extending from the first side edge portion to the second side
edge portion.
34: The prosthetic heart valve of claim 32, wherein the plurality
of pockets each comprise an open edge longitudinally spaced from
the inflow edge of the tubular member and extending from the first
side edge portion to the second side edge portion.
35: A prosthetic heart valve comprising: a radially compressible
and expandable tubular metal frame structure having a longitudinal
axis and extending from an inflow edge along the longitudinal axis
to an outflow edge along the longitudinal axis; and a tubular
member comprising a multi-layer portion defining an inflow edge of
the tubular member and a single-layer portion defining an outflow
edge of the tubular member, the multi-layer portion defining a
plurality of pockets between a first material layer of the
multi-layer portion and a second material layer of the multi-layer
portion; wherein at least a portion of the second material layer is
secured to at least a portion of the first material layer; wherein
each pocket comprises first and second side edge portions; wherein
each pocket comprises an open edge longitudinally spaced from the
inflow edge of the tubular member and extending from the first side
edge portion to the second side edge portion; wherein the second
material layer extends longitudinally from the inflow edge of the
tubular member to the open edge of each pocket; wherein the first
material layer extends longitudinally from the inflow edge of the
tubular member beyond the open edge of each pocket; wherein at
least a portion of the first material layer is longitudinally
positioned within and attached to the metal frame structure;
wherein each pocket comprises an arcuate portion longitudinally
spaced from the inflow edge of the tubular member and having a
continuous arc extending from the first side edge portion to the
second side edge portion; wherein each pocket is configured to stop
a flow of blood.
36: The prosthetic heart valve of claim 35, wherein the tubular
member covers the inflow edge of the metal frame structure.
37: The prosthetic heart valve of claim 35, wherein the tubular
member overlaps the inflow edge of the metal frame structure.
38: The prosthetic heart valve of claim 35, wherein the first and
second material layers comprise different materials.
39: The prosthetic heart valve of claim 35, wherein the first and
second material layers comprise the same material.
40: The prosthetic heart valve of claim 35, wherein the prosthetic
heart valve has a one way fluid passage extending from the inflow
edge of the metal frame structure to the outflow edge of the metal
frame structure.
Description
PRIORITY CLAIM
[0001] This application claims the benefit of United States
Provisional patent application having Ser. No. 60/786,849, filed on
Mar. 28, 2006, entitled "Prosthetic Cardiac Valve Formed from
Pericardium Material and Methods of Making Same", the entire
disclosure of which is incorporated herein by reference for all
purposes.
TECHNICAL FIELD
[0002] The present invention relates generally to treatment of
cardiac heart disease. More particularly, the present invention
relates to implantable valve prostheses for implantation into the
cardiac system.
BACKGROUND OF THE INVENTION
[0003] The heart includes four valves that serve to direct blood
flow through the two sides of the heart. On the left (systemic)
side of the heart are: (1) the mitral valve, located between the
left atrium and the left ventricle, and (2) the aortic valve,
located between the left ventricle and the aorta. These two valves
direct oxygenated blood from the lungs through the left side of the
heart and into the aorta for distribution to the body. On the right
(pulmonary) side of the heart are: (1) the tricuspid valve, located
between the right atrium and the right ventricle, and (2) the
pulmonary valve, located between the right ventricle and the
pulmonary artery. These two valves direct de-oxygenated blood from
the body through the right side of the heart and into the pulmonary
artery for distribution to the lungs, where the blood becomes
re-oxygenated in order to begin the circuit anew.
[0004] All four of these heart valves are passive structures in
that they do not themselves expend any energy and do not perform
any active contractile function. They consist of moveable
"leaflets" that open and close in response to differential
pressures on either side of the valve. Any or all of these heart
valves in a particular patient may exhibit abnormal anatomy and
function as a result of congenital or acquired valve disease.
Congenital valve abnormalities may be well-tolerated for many years
only to develop into a life-threatening problem in an elderly
patient, or may be so severe that emergency surgery is required
within the first few hours of life. Acquired valve disease may
result from causes such as rheumatic fever, degenerative disorders
of the valve tissue, bacterial or fungal infections, and
trauma.
[0005] The problems that can develop with valves can generally be
classified into two categories: (1) stenosis, in which a valve does
not open properly, and (2) insufficiency (also called
regurgitation), in which a valve does not close properly. Stenosis
and insufficiency may occur concomitantly in the same valve or in
different valves. Both of these abnormalities increase the workload
placed on the heart. The severity of this increased stress on the
heart and the patient, and the heart's ability to adapt to it,
determine the treatment options that will be pursued. In some
cases, medication can be sufficient to treat the patient, which is
the preferred alternative; however, in many cases defective valves
have to be repaired or completely replaced in order for the patient
to live a normal life.
[0006] The two general categories of valves that are available for
implantation into the cardiac system are mechanical valves and
bioprosthetic or tissue valves. Mechanical valves have been used
for many years and encompass a wide variety of designs that
accommodate the blood flow requirements of the particular location
where they will be implanted. Although the materials and design
features of these valves are continuously being improved, they do
increase the risk of clotting in the blood stream, which can lead
to a heart attack or stroke. Thus, mechanical valve recipients must
take anti-coagulant drugs for life to lessen the potential for
blood clot formation. Further, mechanical valves can sometimes
suffer from structural problems that may force the patient to have
additional surgeries for further valve replacement.
[0007] Bioprosthetic valves, which are sometimes also referred to
as prosthetic valves, generally include both human tissue valves
and animal tissue valves. Prosthetic heart valves are described,
for example, in U.S. Patent Publication No. 2004/0138742 A1 (Myers
et al.), the entire contents of which are incorporated herein by
reference. The designs of these bioprosthetic valves are typically
relatively similar to the design of the natural valves of the
patient and advantageously do not require the use of long-term
anti-coagulant drugs. Human tissue valves are typically not
available in large quantities since they must be removed from
deceased persons who have elected organ donation; however, because
large numbers of animals are routinely processed at meat processing
facilities, for example, animal tissue valves are more widely
available for the patients who require valve replacement. The most
common types of animal tissue valves used include porcine aortic
valves, and bovine and porcine pericardial valves, some of which
are incorporated with some type of a stent before implantation in a
patient.
[0008] To simplify surgical procedures and reduce patient trauma,
there has been a recent increased interest in minimally invasive
and percutaneous replacement of cardiac valves. Percutaneous
replacement of a heart valve does not involve actual physical
removal of the diseased or injured heart valve. Rather, the
defective or injured heart valve typically remains in position
while the replacement valve is inserted into a catheter and
delivered percutaneously via the vascular system to the location of
the failed heart valve. There, the replacement valve is either
expanded by the balloon or self-expands to compress the native
valve leaflets against the ventricular outflow tract, anchoring and
sealing the replacement valve. In the context of percutaneous,
pulmonary valve replacement, U.S. Patent Application Publication
Nos. 2003/0199971 A1 (Tower, et al.) and 2003/0199963 A1 (Tower, et
al.), describe a valved segment of bovine jugular vein, mounted
within an expandable stent, for use as a replacement pulmonary
valve. As described in the articles "Percutaneous Insertion of the
Pulmonary Valve", Bonhoeffer, et al., Journal of the American
College of Cardiology 2002; 39: 1664-1669 and "Transcatheter
Replacement of a Bovine Valve in Pulmonary Position", Bonhoeffer,
et al., Circulation 2000; 102: 813-816, the replacement pulmonary
valve may be implanted to replace native pulmonary valves or
prosthetic pulmonary valves located in valved conduits. Other
implantables and implant delivery devices also are disclosed in
published U.S. Patent Application Publication No. 2003/0036791 A1
(Bonhoeffer et al.) and European Patent Application No. 1 057
460-A1. In addition, percutaneous heart valves for use as a
replacement pulmonary valve are described in Assignee's co-pending
U.S. Patent Application Publication No. 2006/0206202 A1 (Bonhoeffer
et al.). Like the valves described by Tower et al., the heart
valves of this co-pending application incorporate a valved segment
of bovine jugular vein, which is mounted within an expandable
stent.
[0009] There is, however, a continued need to be able to be able to
provide a variety of different valve assemblies to accommodate the
requirements of different patients, such as by providing stented
valves that can be designed and customized for each individual
patient.
SUMMARY
[0010] The present invention is directed to a prosthetic cardiac
valve and methods of making such a valve. In one embodiment, the
valves of the present invention involve the use of a piece of
pericardium material, such as porcine pericardium, which is folded
over on itself into a two-layer configuration. The layers are
secured to each other in a predetermined pattern to create a series
of arches or arcuate portions and vertical segments. This
pericardium piece is formed into a tube and secured along its
length, which may occur either before or after the predetermined
pattern is made. The tubular segment can then be secured to a stent
to create a stented valve, with the arches and vertical segments
providing the leaflets of a valve. In one embodiment, three arch
segments are provided to make a three leaflet or tri-leaflet valve,
while another embodiment includes a two leaflet or bi-leaflet
valve. The locations between the created arches and the fold line
of the pericardium can act as a barrier to undesired abrasion
between the valve or frame and the leaflets and also to prevent or
minimize valve leakage should any of the valve segments fail. When
the valve is a stented valve, the stent structure of the
configuration is compressible and expandable to facilitate
percutaneous insertion into the heart of a patient.
[0011] In one aspect of the invention, a prosthetic stented heart
valve is provided which comprises a compressible and expandable
stent structure having first and second opposite ends, an expanded
outer periphery, and a compressed outer periphery that is at least
slightly smaller than the expanded outer periphery when subjected
to an external radial force. The heart valve further comprises a
valve segment comprising a dual-layer sheet formed into a generally
tubular shape having at least one longitudinally extending seam,
and a plurality of leaflets formed by attachment of an outer layer
of the dual-layer sheet to an inner layer of the dual-layer sheet
in a leaflet defining pattern. At least a portion of the valve
segment is positioned within at least a portion of the stent
structure, and the stent structure is attached to the outer layer
of the valve segment at one or more of the first and second ends of
the stent structure. The dual-layer sheet may be a single sheet of
material folded to provide a fold line along a first edge of the
sheet, wherein the material on one side of the fold line comprises
the outer layer of the dual-layer sheet and the material on the
opposite side of the fold line comprises the inner layer of the
dual-layer sheet. The surface area on either side of the fold line
may be the same or different. The dual-layer sheet may further
include multiple pieces of material that are attached to each other
along multiple longitudinally extending seams.
[0012] The prosthetic valve may further include at least one
opening in the outer layer of the dual-layer sheet that is spaced
from both the first and second ends of the stent structure. In
particular, a first opening can be configured for fluid
communication with a right coronary artery when the prosthetic
valve is positioned in the ascending aorta of a heart and a second
opening spaced circumferentially from the first opening can be
configured for fluid communication with a left coronary artery.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The present invention will be further explained with
reference to the appended Figures, wherein like structure is
referred to by like numerals throughout the several views, and
wherein:
[0014] FIG. 1 is a top view of a piece of material, such as
pericardium material, that is folded over onto itself to make a
dual-layer configuration, in one step of being formed into a
cardiac valve in accordance with the invention, including a pattern
of attaching two layers of material to create a leaflet
configuration;
[0015] FIG. 2 is a front view of the piece of material of FIG. 1
formed into a tubular valve segment;
[0016] FIG. 3 is a front view of an assembly showing an exemplary
initial placement of a stent over the valve segment of FIG. 2, with
both the stent and valve segment positioned on a mandrel;
[0017] FIG. 4 is an end view of the assembly of FIG. 3 from the
side of the heart into which the blood of a patient would normally
flow;
[0018] FIGS. 5 and 6 are top views of exemplary templates that can
be positioned on top of the material that will be made into a
cardiac valve to provide a guide for stitching patterns that can be
followed in making a valve;
[0019] FIG. 7 is a front view of an embodiment of a cardiac valve
and stent assembly of the invention;
[0020] FIG. 8 is a front view of another embodiment of a cardiac
valve and stent assembly of the invention;
[0021] FIG. 9 is a perspective view of a valve segment of the
invention with a portion of the outer tube material removed;
[0022] FIG. 10 is a perspective view of a valve segment of the
invention with a smaller portion of the outer tube material removed
as compared to the embodiment of FIG. 9, thereby leaving a top
portion of the valve segment intact;
[0023] FIG. 11 is perspective view of another valve segment of the
invention with a portion of the outer tube material removed to
allow a particular flow of fluid through the valve;
[0024] FIG. 12 is a cross-sectional side view of a cardiac valve of
the invention positioned relative to a cardiac vessel;
[0025] FIG. 13 is a top view of an embodiment of a piece of
dual-layer material having another leaflet and attachment pattern,
which is capable of being formed into a cardiac valve in accordance
with the invention;
[0026] FIGS. 14 and 15 are end views of a tubular valve made of the
piece of material of FIG. 13, where FIG. 14 shows the valve with
leaflets in their open position and FIG. 15 shows the valve with
leaflets in their closed position;
[0027] FIG. 16 is a top view of another embodiment of a piece of
dual-layer material having another alternative leaflet and
attachment pattern;
[0028] FIGS. 17 and 18 are end views of a tubular valve made of the
piece of material of FIG. 16, where FIG. 17 shows the valve with
leaflets in their open position and FIG. 18 shows the valve with
leaflets in their closed position;
[0029] FIG. 19 is a top view of three separate dual-layer material
pieces having one embodiment of a leaflet pattern;
[0030] FIGS. 20 and 21 are end views of a tubular valve made of the
three pieces of material of FIG. 19, which are attached to each
other in the form of a tubular valve, where FIG. 20 shows the valve
with leaflets in their open position and FIG. 21 shows the valve
with leaflets in their closed position;
[0031] FIG. 22 is a top view of two separate dual-layer material
pieces having one embodiment of a leaflet pattern;
[0032] FIGS. 23 and 24 are end views of a tubular valve made of the
two pieces of material of FIG. 22, which are attached to each other
in the form of a tubular valve, where FIG. 23 shows the valve with
leaflets in their open position and FIG. 24 shows the valve with
leaflets in their closed position;
[0033] FIG. 25 is a top view of an embodiment of a dual-layer
material having another leaflet and attachment pattern;
[0034] FIG. 26 is a perspective view of the piece of material of
FIG. 25 formed into a tubular valve segment;
[0035] FIG. 27 is a top view of a dual-layer material having
another leaflet and attachment pattern; and
[0036] FIG. 28 is a perspective view of the piece of material of
FIG. 27 formed into a tubular valve segment.
DETAILED DESCRIPTION
[0037] Referring now to the Figures, wherein the components are
labeled with like numerals throughout the several Figures, and
initially to FIG. 1, an intermediate configuration for preparing an
exemplary pericardial valve in conjunction with the methods and
valves of the present invention is illustrated. The pericardial
valves of the invention can be used for replacement of pulmonary
valves, aortic valves, mitral valves, or tricuspid valves, in
accordance with the methods of the invention described herein.
Alternatively, the valves of the invention can be used to replace a
failed bioprosthesis, such as in the area of an aortic valve or
mitral valve, for example. The shape, size, and configuration of
the outer tubular portion of the pericardial valve can specifically
be designed and chosen for the type of valve that is being
produced. The valves of the invention can include stented or
stentless valves, but in either case, the valves are compressible
to a reduced diameter during the implantation process, such as
transcatheter implantation, and are capable of being expanded to a
larger diameter once they are in their desired implantation
location. The valve assemblies can be used as a surgical sutureless
or apical implant, and can be utilized in percutaneous replacement
of cardiac valves, for example. One exemplary method for assembling
a stented valve of the invention generally includes the manufacture
and preparation of a valve segment, then a subsequent mounting or
attachment of the prepared valve segment to a stent, which is
described in further detail below.
[0038] In accordance with the invention, a relatively flat sheet of
pericardium material 10 is provided, which may be obtained, for
example, from a porcine heart. It is understood that other donor
species may alternatively be used, or that the material used is not
a pericardium material but instead is a different type of tissue or
material, such as a polymer or bio-engineered film. The pericardium
material 10 may be at least partially fixed or cross-linked with a
buffered gluteraldehyde solution or other solution at some point
during the assembly process, in order to make the material easier
for an operator to handle and manipulate. In one specific example,
a piece of porcine pericardium is obtained, which is rinsed for
approximately 10 minutes in a buffered gluteraldehyde solution to
partially cross-link the material. U.S. Pat. No. 4,976,733
(Girardot), titled "Prevention of Prosthesis Calcification",
describes a variety of additional exemplary methods of treating
pericardium material that may be useful with the systems and
methods of the present invention, along with methods for retarding
or preventing the calcification of a prosthesis implanted in a
mammal. However, such treatments to the material are optional and
may be different depending on operator preference, the material
chosen, and the like.
[0039] The piece of pericardium can then be cut to a predetermined
shape and size, such as the rectangular piece of pericardium
material 10 illustrated in FIG. 1. If the material 10 is thicker
than desired, the thickness can be reduced using any of a number of
methods for effectively removing some of the thickness of the
pericardium material without sacrificing an undesirable amount of
the strength of the material.
[0040] In accordance with one aspect of the invention, the
pericardium material 10 includes a first surface 12 and an opposite
second surface 14. The pericardium material 10 is folded on itself
at fold line 16 to effectively double the thickness of at least a
portion of the material 10. In this way, two portions of the first
surface 12 will be in contact with each other adjacent to the fold
line 16 and in any area where the material is doubled. In one
exemplary embodiment of the invention, a portion of the material 10
having a length 20 has a double thickness and at least a portion of
the pericardium material extends beyond the area having a double
thickness, thereby leaving a portion of the material having a
length 18 with a single material thickness. The portion having a
double thickness may have a greater or smaller length 20 than the
length 18 of the single thickness portion, or there may be
essentially no portion having a single thickness (i.e., the
material 10 is folded exactly in half).
[0041] As shown, the sheet of pericardium material 10 includes a
free edge 22 that is spaced from the fold line 16 and corresponds
with one end of the doubled portion. Thus, free edge 22 is
immediately adjacent to the single thickness portion 18 and is
preferably generally parallel to the fold line 16, although it is
possible that the edge 22 and fold line 16 are not parallel to each
other. The two portions of the pericardium material 10 in the
doubled portion are then stitched, or otherwise attached to each
other in an attachment pattern similar to that shown in FIG. 1.
This attachment pattern includes three shaped portions 24, 26 and
28, each of which will correspond to a leaflet for a cardiac valve.
In this embodiment, the pericardial valve is prepared to include
three leaflets, as shown, but may optionally have more or less than
three leaflets, which can be formed by varying the pattern to
include more or less than three shaped portions. The three leaflet
embodiment can be used in areas of the heart that typically have a
three leaflet valve, such as the pulmonary valve and aortic valve,
although the three leaflet embodiment can also be used as a
replacement for the two leaflet mitral valve. Alternatively, a two
leaflet or single leaflet embodiment of the valve of the invention
is contemplated, which can be used in areas of the heart that
typically have a three leaflet valve, such as the pulmonary valve,
for example. Certain considerations for blood flow will determine
particular parameters of the valve used, as will be explained in
further detail below.
[0042] The shaped portion 26 of the attachment pattern includes two
vertical components 30, which are spaced from each other by a
distance that represents the desired width of a leaflet, and an
arcuate portion 32 extending between the two vertical components
30. The vertical components 30 are generally linear and are
preferably also generally parallel to each other. Alternatively,
the vertical components 30 can be arranged to provide a funnel
shape to the attachment pattern. The length of the vertical
components 30 can be chosen to correspond to the desired depth of a
pocket, such that a pattern including relatively long vertical
components 30 will provide bigger or deeper pockets than a pattern
having relatively short vertical components 30. In accordance with
the invention, the length of the vertical components 30 can be
particularly designed and selected to correspond with a desired
depth of the pockets, which selection is not available when using a
native valve, for example. In addition, the amount of material that
extends above and below the valves can be particularly designed and
selected to provide a valve that meets certain criteria desired by
the surgeon, such as for ease of implantation or to provide a valve
that has additional durability, for example.
[0043] In any case, all of the vertical components 30 within a
particular pattern can have the same or nearly the same length in
order to create leaflets that are identically or nearly identically
shaped and sized. In that respect, all of the vertical components
30 can also be spaced at the same distance from each other, and
also can be spaced at a distance from a corresponding edge (e.g.,
vertical or side edge 34 or 36) that will facilitate making the
width of all of the shaped portions 24, 26, 28 the same for a
particular piece of pericardium material 10, as will be described
in further detail below. However, it is also contemplated that the
vertical components 30 within a single pericardial valve
configuration can have different lengths and/or can be spaced at
different distances from each other in order to create a valve with
leaflets that are not all identically sized and/or shaped.
[0044] The pericardial material may be cut into the desired shape
using a number of methods and apparatus, such as cutting the
material with a scalpel, scissors, die, or laser. Alternatively,
the attachment pattern can be determined and controlled by using a
template that is positioned over the material, which may be made
out of a material such as the relatively thin and translucent
material commercially available under the trade name "Mylar". Two
examples of such templates 60 and 70 are illustrated in FIGS. 5 and
6, respectively. The templates 60 and 70 each show a general
outline that will be followed for making a valve. The tissue can be
placed within a frame or other support structure to hold it in
place for the securing operation, and the appropriate template can
then be aligned with the tissue and tacked into place. The template
60 of FIG. 5, which includes a margin 62 that is relatively
straight across the width of the template 60, illustrates one
pattern that may be followed for a standard valve, while the
template 70 of FIG. 6, which includes a margin 72 having portions
that are angled relative to each other, illustrates one exemplary
pattern that may be followed for a valve. The choice of a margin
that is straight, angled, curved, or otherwise configured can be
particularly selected to change the stresses that will be created
on the leaflets of the valve, which depends at least partially on
the particular location or position of the valve in a patient
(e.g., in the area of the aortic valve or the pulmonary valve).
[0045] As shown, the pattern of template 60 includes arcuate
portions 64 and vertical components 66, and the pattern of template
70 includes arcuate portions 74 and vertical components 76. The
template 60 may further include tab portions 67 that extend beyond
vertical stitch lines 68 on both sides of the pattern which can
provide a piece of material for use in securing the material into a
tube shape. That is, the tab portions provide an extending portion
that can be grasped or held during the process of making the
material into a tube. The template 70 includes similar tab portions
77 that extend beyond the vertical stitch lines 78 for the same
purpose.
[0046] As set out above, the two thicknesses of the pericardium
material 10 can be attached to each other along leaflet-defining
patterns in a variety of ways, including stitching, suturing, or
clamping. The suture material may be provided as a monofilament or
multifilament structure made of natural or synthetic material
(e.g., nylon or polypropylene), or may alternatively include an
elongated metal or metal-composite thread or filament that is
suitable for securing layers of pericardium material to each other.
The stitching and suturing techniques will typically involve using
an elongated thread-like material that may be attached to a needle
to perform the securing function, which may either be done by hand
or with an automated machine. Referring again to FIG. 1, such
techniques would typically include pushing the needle repeatedly
through both thicknesses of the pericardium material 10 in an
outline shape that matches the desired pattern. Other attachment
methods may also be used, including adhesives or other attachment
materials that are placed in the desired attachment pattern between
the two layers of the material 10, which are then pressed together
to secure the first surface 12 to itself in the area between the
edge 22 and the fold line 16. The attachment pattern preferably
does not extend into the area 18 where the pericardium 10 is a
single thickness since such stitching would serve no securing
purpose. However, each of the vertical components 30 of the
attachment pattern preferably has one end that terminates generally
at the edge 22 of the pericardium material 10, although it is
possible that the end of each vertical component 30 that is closest
to the edge 22 actually terminates at a distance that is spaced at
least slightly from the edge 22 toward the fold line 16.
[0047] The attachment pattern preferably extends from the edge 22
of the pericardium material 10 for a predetermined distance toward
the fold line 16, but preferably does not extend all the way to the
fold line 16. In this way, an area 37 of the pericardium material
10 that is between the arcuate component 32 of each of the shaped
portions 24, 26, 28 and the fold line 16 includes two layers of
material that are not secured to each other. For illustration
purposes, the area 37 is a portion of the pericardium material 10
in FIG. 1.
[0048] Referring additionally to FIG. 2, the piece of pericardium
material 10 of FIG. 1, which includes the leaflet pattern described
above, is then formed into a tubular shape, with the edge 22
positioned in the interior portion of the tubular shape. In order
to provide the tubular configuration, the material may be formed
around a mandrel or some other rigid cylindrical device.
Alternatively, the material can be formed into a tubular shape
without the use of a mandrel or forming device. As shown, the side
edges 34, 36 of the material 10 generally meet each other at the
top of the tube, with the fold line 16 illustrated at the right
side of the tube. Edge 22 of material 10 is preferably positioned
to be facing the interior area of the tube, which will facilitate
the operation of the leaflets, as will be described below. After
forming the material 10 into a tubular shape, the material 10 is
secured along an attachment line 38 by stitching, suturing, or
otherwise attaching the multiple thicknesses of material to each
other. Attachment line 38 is preferably positioned to be as close
to the edges 34, 36 as possible, although it is important that the
attachment line 38 is not so close to the edges 34, 36 that there
will be a risk of the stitches tearing through the material 10 or
otherwise damaging the material 10. This attachment line 38 is
preferably spaced at the same or a similar distance from each of
the vertical components 30 as the distance between the vertical
components 30 in FIG. 2. In this way, all of the shaped portions
24, 26, 28 will have a similar width, which will result in leaflets
that are very similar or identical in size and shape. This tube of
pericardium material 10 having leaflets that are formed by the
shaped portions 24, 26, 28 may be referred to as a tubular valve
segment 40.
[0049] The above description of the steps involved in making a
valve segment in accordance with the invention provides the
advantage of being able to perform the attachment work for the
shaped portions with a flat sheet of pericardium material; however,
this sequence of construction is only one exemplary way of
achieving such a construction. In another alternative method, a
flat sheet of pericardium material can be made into a tube by
attaching opposite ends of the material to each other in a tubular
shape. A portion of the pericardium material can then be folded
into the inside of the tube, thereby creating an inner tube and an
outer tube that is closed at the folded end and open at the
opposite end. The contours or patterns for the shaped portions that
will act as leaflets are then formed by stitching or otherwise
attaching the two layers of material to each other, with the inflow
end of the structure at the closed end of the tube and the
commissures at the open end of the tube.
[0050] As described above, the area 37 between the arcuate
components of the shaped portions 24, 26, 28 and the fold line 16
is an area comprising two layers of pericardium material that are
not attached to each other. Once the pericardium material 10 is
formed into a tube and the leaflets are formed, as described above,
the area 37 is essentially an enclosed pocket area, which can serve
as a backup if there are any failures in the attachment lines of
the shaped portions 24, 26, and/or 28. That is, if one or more
stitches or an adhesive area become unattached along some part of
the shaped portions, the valve can continue to operate within the
heart of a patient because the area at the fold line 16 will stop
the flow of blood that might otherwise leak from the valve segment
40.
[0051] FIGS. 13 through 15 illustrate another configuration of a
tri-leaflet valve having a single side seam when assembled. In
particular, FIG. 13 shows a dual-layer sheet of material 140 with a
scalloped pattern that is positioned between two side vertical seam
lines 142 that are spaced from each other. The pattern further
includes two leaflet-defining seams 144 and 146 that are spaced
from each other and positioned between the vertical seam lines 142.
As described above, the seam lines 142 are each preferably spaced
at an equal distance from their corresponding adjacent seams 144 or
146, and seams 144 and 146 are also preferably spaced at the same
distance from each other that each is positioned from the seam
lines 142. However, these distances may be different, if desired.
In a further alternative, the seam lines can be positioned relative
to each other to provide a funnel shaped pattern. In any case, the
two layers of the dual-layer sheet 140 are attached to each other
generally along this pattern, such as with stitching, adhesives, or
other attachment methods.
[0052] The sheet of material 140 is formed into a tubular structure
having an interior layer 150 positioned closer to the central area
of a valve 154, and an outer layer 152 adjacent to the interior
layer 150 and positioned further from the central area of the valve
154. The two seam lines 142 are generally aligned with each other
and can be connected or otherwise attached to each other using a
number of attachment methods, such as sewing. The valve 154 can
then be attached to a compressible stent or other compressible
structure for percutaneous delivery to the heart of a patient, for
example. An open position of the valve 154 is shown in FIG. 14,
where the interior layer 150 has generally the same shape as the
outer layer 152 (e.g, circular, as shown). A closed position of the
valve 154 is shown in FIG. 15, where the interior layer 150 is
scalloped or shaped to provide three leaflets.
[0053] While the stitching patterns described herein often refer to
seam lines between leaflets that are generally parallel to and
evenly spaced from each other, the pattern may be differently
configured. For example, one or more of the seams may be angled or
otherwise positioned relative to one or more adjacent seams to
create relatively funnel-shaped patterns for the leaflets. These
configurations may alternatively be used in embodiments of the
invention that are otherwise described herein as having patterns
with walls that are generally parallel to one another. It is
further contemplated that a combination of parallel and
non-parallel spacing of seams in a pattern can be used.
[0054] FIGS. 16 through 18 illustrate a configuration of a
bi-leaflet valve having a single side seam when assembled. In
particular, FIG. 16 shows a dual-layer sheet of material 170 with a
scalloped pattern that is positioned between two side vertical seam
lines 172 that are spaced from each other. The pattern further
includes a leaflet-defining seam 174 that is positioned between the
vertical seam lines 172. As described above, the seam line 172 is
preferably spaced at the same distance from each of the seam lines
172. However, these distances may be different, if desired. In any
case, the two layers of the dual-layer sheet 170 are attached to
each other generally along this pattern, such as with stitching,
adhesives, or other attachment methods.
[0055] The material 170 is formed into a tubular structure having
an interior layer 180 positioned closer to the central area of a
valve 184, and an outer layer 182 adjacent to the interior layer
180 and positioned further from the central area of the valve 184.
The two seam lines 172 are generally aligned with each other and
can be connected or otherwise attached to each other using a number
of attachment methods, such as sewing. The valve 184 can then be
attached to a compressible stent or other compressible structure
for percutaneous delivery to the heart of a patient, for example.
An open position of the valve 184 is shown in FIG. 17, where the
interior layer 180 has generally the same shape as the outer layer
182 (e.g, circular, as shown). A closed position of the valve 184
is shown in FIG. 18, where the interior layer 180 is scalloped or
shaped to provide two leaflets.
[0056] FIGS. 19 through 21 illustrate another configuration of a
tri-leaflet valve that has three side seams instead of one when
assembled. In particular, FIG. 19 includes first, second, and third
pieces of dual-layer material 200, 201, 202, respectively, each of
which may be a dual-layer piece of pericardium material or other
material, which may be provided with two separate material pieces
or by folding a piece of material along a fold line to create two
material layers. First piece 200 includes vertical side seam lines
203, 204, second piece 201 includes vertical side seam lines 205,
206, and third piece 202 includes vertical side seam lines 207,
208. Each seam line of each pair of vertical side seam lines is
spaced from the other seam of that pair of vertical side seam lines
on its respective first, second or third material piece 200, 201,
or 202. For example, side seam line 203 is spaced from side seam
line 204 on first piece 200. In addition, each piece 200, 201, 202
includes a scalloped pattern for a leaflet that is positioned
between its two side vertical seam lines, where each of the two
vertical components of each of the scalloped patterns generally
coincides with one of the vertical side seams. Each of the three
pieces 200, 201, 202 can be identical in size in shape and also
include identically sized and shaped patterns for the leaflets.
Alternatively, the three pieces 200, 201, 202 can have somewhat
different sizes, shapes, and/or patterns for the leaflets. In any
case, the two layers of the dual-layer material that comprise each
of the first, second, and third pieces 200, 201, 202 are attached
to each other generally along their respective patterns, such as by
stitching, adhesives, or other attachment methods.
[0057] The first, second, and third pieces 200, 201, 202 are formed
into a tubular structure by attachment at their vertical side seam
lines, such as is illustrated in FIGS. 20 and 21. In this
embodiment, side seam lines of three adjacent pieces are assembled
so that side seam lines 203 and 208 are generally aligned with and
adjacent to each other, side seam lines 204 and 205 are generally
aligned with and adjacent to each other, and side seam lines 206
and 207 are generally aligned with and adjacent to each other,
thereby forming a tubular structure. Each of the pieces can be
connected or otherwise attached to each other along these pairs of
seam lines using a number of attachment methods, such as sewing. In
this way, an interior tissue layer 210 will be positioned closer to
the central area of a valve 214, and an outer layer 212 will be
adjacent to the interior layer 210 and spaced further from the
central area of valve 214. The valve 214 can then be attached to a
compressible stent or other compressible structure for percutaneous
delivery to the heart of a patient, for example. An open position
of the valve 214 is shown in FIG. 20, where the interior layer 210
has generally the same shape as the outer layer 212 (e.g, circular,
as shown). A closed position of the valve 214 is shown in FIG. 21,
where the interior layer 210 is scalloped or shaped to provide
three leaflets.
[0058] FIGS. 22 through 24 illustrate a configuration of a
bi-leaflet valve having two side seams when assembled. In
particular, FIG. 22 includes first and second pieces of dual-layer
material 220, 222, respectively, each of which may be a piece of
pericardium material. First piece 220 includes vertical side seam
lines 223, 224 and second piece 222 includes vertical side seam
lines 225, 226. Each piece 220, 222 includes a scalloped pattern
for a leaflet that is positioned between its two side vertical seam
lines, where each of the two vertical components of each of the
scalloped patterns generally coincides with one of the vertical
side seams. The two layers of the dual-layer material that comprise
each of the first and second material pieces 220, 222 are attached
to each other generally along their respective patterns, such as by
stitching, adhesives, or other methods.
[0059] The first and second material pieces 220, 222, are formed
into a tubular structure by attachment at their vertical side seam
lines, such as is illustrated in FIGS. 23 and 24. In this
embodiment, side seam lines 224 and 225 are generally aligned with
and adjacent to each other, and side seam lines 223 and 226 are
generally aligned with and adjacent to each other, thereby forming
a tubular structure. In this way, an interior layer will be
positioned closer to the central area of a valve 232, and an outer
layer 230 will be positioned adjacent to the interior layer 228.
The valve 232 can then be attached to a compressible stent or other
compressible structure for percutaneous delivery to the heart of a
patient, for example. An open position of the valve 232 is shown in
FIG. 23, where the interior layer 228 has generally the same shape
as the outer layer 230 (e.g, circular, as shown). A closed position
of the valve 232 is shown in FIG. 24, where the interior layer 228
is scalloped or shaped to provide two leaflets.
[0060] FIG. 25 illustrates an alternative embodiment of a pattern
for forming leaflets, which includes a dual-layer sheet of material
240 with layers that are attached to each other along a more
rectangular pattern 244 for leaflets, as compared to the scalloped
or arched shapes discussed above. The sheet of material 240 is
formed into a tubular shape, such as by using the attachment and
forming methods described herein, to create a valve 242 having more
rectangular shaped leaflets, as shown in FIG. 26.
[0061] FIG. 27 illustrates yet another alternative embodiment of a
pattern for forming leaflets, which includes a dual-layered sheet
of material 250 with layers that are attached to each other to form
a polygonal pattern for leaflets. One exemplary shape of the
leaflets is defined by two relatively vertical components 252, 254,
a relatively horizontal component 256, and two angled components
258, 260. Angled component 258 extends from component 256 to
component 252, and angled component 260 extends from component 256
to component 254. The angle at which these angled components are
positioned can be between at least slightly greater than
approximately 0 degrees and at least slightly smaller than
approximately 90 degrees. The triangular areas created by these
angled components can eliminate or minimize possible areas of
stasis and can also provide a non-abrasive surface over which the
corresponding leaflet can hinge. The sheet of material 250 is
formed into a tubular shape, such as by using the attachment and
forming methods described herein, to create a valve 262 having
polygonal shaped leaflets, as shown in FIG. 28.
[0062] Referring again to FIGS. 1 and 2, the valve segment 40
described above, and any other embodiments of a valve segment of
the invention, may be used alone as a stentless valve, or the valve
segments may be attached to a support structure such as a stent.
One exemplary configuration for mounting the valve segment 40 to a
stent 42 is illustrated in FIG. 3. The stent 42, like most
compressible and expandable cylindrical stents, generally takes the
form of a series of zig-zag ring structures. The stent 42
illustrated corresponds generally to a stent of the type described
in the above-cited Tower et al. and Bonhoeffer et al. references,
for example. The stent 42 may be fabricated of platinum, stainless
steel, or other biocompatible metal or polymer. Stent 42 may
alternatively be fabricated using wire stock or may be produced by
machining the stent from a metal tube, as is commonly employed in
the manufacturing of stents. The number of wires, the positioning
of such wires, and various other features of the stent chosen can
vary considerably from that shown in FIG. 3. Thus, the specifics of
the stent can vary widely, such that many other known generally
cylindrical stent configurations may be used within the scope of
the invention. The series of zig-zag ring structures of the
illustrated embodiment are coupled longitudinally to one another to
form a generally cylindrical-shaped structure, although it is
understood that the structures can be arranged in an at least
slightly oval or elliptical shape. Each ring structure takes the
form of a series of adjacent generally straight sections (e.g., 44,
46), which each meet one another at one end at a curved or angled
junction (e.g., junction 48) to form a "V" or "U" shaped
structure.
[0063] In order to attach the tubular valve segment 40 to stent 42,
the segment 40 may be partially or completely slid onto a mandrel
50, and the stent 42 can be slid over the top of the segment 40. It
may be desirable to slide the tubular valve segment 40 onto the
mandrel for only a portion of its length and slide the stent 42
over the segment at this point, then slide the combination of the
segment 40 and the stent 42 until the remainder of the length of
the segment 40 is on the mandrel. This may make it easier to keep
the stent 42 positioned relative to the length of the segment 40,
although it is possible to position these two components
independently on the mandrel and relative to each other. It is also
possible to position the valve segment relative to the stent
without the use of any mandrel or other device.
[0064] Once the tubular valve segment 40 and stent 42 are
positioned relative to each other so that the formed leaflets are
enclosed entirely within the length of the stent 42, the stent 42
can be secured to the tubular segment 40 in a variety of ways. One
procedure that can be used is to suture certain areas of the stent
42 to the tubular valve segment 40. Exemplary stitches are
illustrated at one end of the stent in FIG. 3. The suture material
may be provided as a monofilament or multifilament structure made
of natural or synthetic materials (e.g., nylon or polypropylene),
or may alternatively include an elongated metal or metal-composite
thread or filament that is suitable for permanently securing the
stent 42 to the tubular valve segment 40 in accordance with the
present invention. The number and location of suture points can
vary, but should include an adequate number of connection points
that are positioned in predetermined locations that prevent
movement of the stent 42 relative to the tubular valve segment 40,
particularly during the compression of the stent for percutaneous
delivery and expansion of the stent for its deployment. These
attachment locations may include some or all of the bases of the
"V's" at one or both ends of the stent 42, and may further include
attachment at other areas intermediate to the ends of the stent 42.
It is important, however, that the materials used for attaching the
stent to the valve segment 40 do not interfere with the operation
of the leaflets. That is, there should be no stitching or other
attachment devices or configurations that extend through both
layers of material and into the central area of any of the shaped
portions 24, 26, 28, since such stitching could undesirably
restrict certain movements of the leaflets, such as the efficient
opening and closing of the leaflets when the valve is at the
implant site of the patient.
[0065] Following the procedure of securing the stent 42 to the
tubular valve segment 40, the stented valve can be removed from the
mandrel 50. The edges of the tubular valve segment 40 extending
beyond the stent 42 can optionally be trimmed to generally follow
the contour of the edges of the stent 42; however, such a trimming
operation may not be necessary or desirable in some applications.
After removal of the valve segment 40 with attached stent 42
(referred to herein as a "stented valve 52") from the mandrel, one
or more shaping tools may be temporarily inserted into the end of
the stented valve 52 that is opposite the folded end 16 and into
the pockets formed by the shaped portions 24, 26, 28. This
procedure essentially forms a stented valve having three leaflets,
where the shaping tool forces the leaflets into their closed
position or configuration. FIG. 4 illustrates an end view of the
valve segment 40 with attached stent 42 after removal of the
shaping tool or tools, where the shaped portions 24, 26, 28 have
been formed and crosslinked into leaflets that are shown in their
closed positions.
[0066] After the tubular valve segment 40 is secured to a stent, it
is contemplated that either one or both ends of the segment 40 may
be rolled or folded back toward the stent, thereby increasing the
thickness of the valve in these areas, as is illustrated in FIGS. 7
and 8, for two examples. In particular, FIG. 7 illustrates a
stented valve 100, which includes a stent 102, a tubular valve
segment 104 positioned at least partially within the stent 102, and
first and second opposite ends 106, 107. Stented valve 100 further
includes a portion 108 of tubular valve segment 104 that has been
rolled or folded back over a portion of the stent 102 at end 106.
Alternatively a portion of tubular valve segment 104 can be rolled
or folded back over a portion of the stent 102 at the opposite end
107. Similarly, FIG. 8 illustrates an embodiment of a stented valve
110, which includes a stent 112, a tubular valve segment 114
positioned at least partially within the stent 112, and first and
second opposite ends 116, 118. Stented valve 110 further includes
rolled or folded back portions 120, 122 at opposite ends 116, 118,
respectively. When both ends 116, 118 include such rolled or folded
portions, the length of these portions may be the same or different
from each other at opposite ends of the stented valve 110.
[0067] In the embodiments described above relative to FIGS. 7 and
8, the tubular valve segments of stented valves of the invention
have a ring of pericardial material that is thicker at one or both
of its ends where the material is rolled or folded back on itself.
This rolled-back material can overlap or cover the edge of the
stent, such as to cover the edge of the stent wires, thereby making
the edge or edges of the stented valve smoother. Alternatively, the
material may be rolled or folded back in such a way that it does
not cover the edge of the stent. For example, a folded portion of
material can be positioned so that it is adjacent to an end of a
stent and/or the folded portion of material can be positioned to
face the interior opening or portion of the stent. In any case, the
extra thickness of the material can be beneficial to prevent the
stented valve from leaking around its perimeter when implanted in a
patient. That is, the rolled or folded areas can help to stabilize
the stented valve within the patient and can also extend into areas
of the implant site that have a larger diameter as compared to the
rest of the implant site. One exemplary positioning of the stented
valve 110 in the ascending aorta 138 of a heart is illustrated in
FIG. 12, with the portions 120, 122 that have additional thickness
being positioned for sealing against the aortic walls. These rolled
or folded areas can include only one additional thickness of
material, such as by folding the pericardial material back once on
itself, or may include multiple additional thicknesses of material,
such as by folding or rolling the pericardial material back on
itself multiple times. The distance that these areas protrude from
the outer sides of the stent will thus depend at least partially on
the number of layers of pericardial material in these areas and can
therefore be provided with greater numbers of layers when a larger
diameter area of the stented valve is desired.
[0068] Because the outer layer of pericardium material of the
stented valve 52 (i.e., the layer that comprises the tubular valve
segment 40) extends along essentially the entire length of the
valve 52, as shown in FIGS. 3 and 4, for example, the leaflets are
protected from contacting the wires or other materials from which
the stent 42 is made when the leaflets are in an open position. In
this embodiment, the leaflets will contact the outer layer of
pericardium material when in their open position, thereby
minimizing wear and abrasion on the leaflets. Thus, one embodiment
of the invention includes maintaining the entire outer layer of
pericardium material for the stented valve along the length of the
valve to completely enclose and protect the leaflets of the valve.
Such an embodiment of the stented valve can be used in areas where
the flow of fluid moves through the ends of the valve, such as in
the area of the pulmonic valve. That is, because this embodiment
does not allow for fluid flow through the sides of the stented
valve, this valve would not typically be used in areas that require
such a flow of fluid.
[0069] However, FIGS. 9-11 illustrate embodiments of valves of the
invention that have portions of the outer layer of material
removed, which may be used with or without an outer stent. In
particular, FIG. 9 illustrates a valve 80 of the invention, which
includes multiple leaflets 84 that are shown in broken lines
because they are positioned within the interior area of the valve
80. Sections 82 of the material of the outer tube are removed to
allow for blood flow to and from the adjacent anatomy, such as the
coronary arteries if the valve 80 is positioned for replacement of
the aortic valve. That is, the sections 82 can be positioned for
fluid communication with the sinus openings, such as in the area
generally designated by reference numeral 139 in FIG. 12. The
sections 82 extend generally from an area near the edge of the
leaflets to the opposite edge of the valve, leaving a central
support in the commissure area between the leaflets. The open
sections 82 would allow for blood flow through the coronary
arteries when the valve is closed.
[0070] Referring now to FIG. 10, a valve 90 of the invention is
illustrated, which includes multiple leaflets 94 that are shown in
broken lines. Sections 92 of the material of the outer tubular
segment are removed to allow for flow to and from the adjacent
anatomy, such as the coronary arteries. However, these sections 92
do not extend along as much of the length of the valve 90 as the
sections 82 of the valve 80. Rather, these holes 92 are smaller and
differently configured along the length of the valve 90. The valve
90 is preferably configured to allow fluid communication with
certain number and spacing of anatomical vessels. For example, if
the valve 90 is to be used in the area of the aortic valve, the
valve preferably will include at least one opening for fluid
communication with the right coronary artery and at least one
opening for fluid communication with the left coronary artery.
Thus, valve 90 may include only two openings 92; however, such a
valve 90 would then need to be "clocked" or rotated so that one of
the openings 92 lines up with the left semilunar cusp of the native
valve and the other opening 92 lines up with the right semilunar
cusp. In order to provide more flexibility in the positioning of
valve 90, it may instead be provided with three openings 92 so that
any two of the three openings 92 can be lined up with the left and
right semilunar cusps and the other opening 92 can be lined up with
the posterior semilunar cusp, although this opening 92 would not be
in fluid communication with an artery as the other openings 92 will
be.
[0071] FIG. 11 illustrates yet another valve 130 of the invention,
which includes multiple leaflets 134 that are shown in broken
lines. Leaflets 134 generally extend up to a point 136 at the
commissures between adjacent leaflets. Sections 132 of the material
of the outer tubular segment again are removed to allow for flow to
and from the adjacent anatomy, such as is described above relative
to FIG. 10. The openings 132 of valve 130, however, do not extend
beyond the point 136. This can provide more area of the outer
tubular structure against which the leaflets can open.
[0072] Preferably, when any portion of the outer layer of material
of one of the valves of the invention is removed, the material is
removed uniformly relative to each leaflet, in order to keep the
valve structurally balanced. In addition, the amount and location
of material removed from the outer layer of the valve should be
designed to maintain protection of the leaflets from contact with
the stent material, when a stent is used. That is, the holes made
by the removal of material should be small enough and/or be
oriented properly to prevent the free edge of the valve from
contacting the stent through the hole in the outer layer of
material. However, the material removed from the outer layer of the
valve should correspond with the desired blood flow, such as being
large enough and able to be aligned in the aortic position relative
to the coronary blood flow.
[0073] Referring again to FIGS. 3 and 4, the stented valve 52 can
be subjected to suitable chemical fixation and/or bioburden
reduction treatments, which may vary considerably depending on the
particular requirements for storage and use of the stented valve
52. Chemical fixation helps to preserve the tissue, render it
inert, reduce the risk of host rejection, and/or the like. Chemical
fixation may occur by submerging the valve in a suitable reagent
for a period of about 3 hours under slight pressure and ambient
temperature and then for 72 hours under ambient pressure and
temperature. By way of example, a 0.2 weight percent gluteraldehyde
solution at physiological pH and being phosphate buffered may be
used for chemical fixation. The valve may then be stored in a
suitable storage reagent (e.g., an aqueous solution containing 0.2%
by weight gluteraldehyde) until subsequent use. Bioburden reduction
may be carried out by submerging the tissue in a suitable reagent
for a period of 48 to 72 hours at ambient temperature. By way of
example, an aqueous solution containing 1% by weight gluteraldehyde
and 20% by weight isopropyl alcohol at physiological pH and being
phosphate-buffered may be used for bioburden reduction. This
solution would be suitable for use as a packaging solution as well.
A variety of fixation tines, concentrations, pH levels and
chemicals can be used in accordance with the invention. After
suitable treatments to the valve 52 are complete and after
appropriate rinsing of the valve, the device can be used for
implantation into a human.
[0074] The stented valve 52 may then be used with a system for
delivering the valve segment to the desired location within a
patient. The delivery system may include, for example, an outer
sheath overlying an inner balloon catheter, where the outer sheath
includes an expanded distal portion, within which the stented valve
is located. The stented valve can be compressed around a single or
double balloon located on the inner catheter. A tapered tip is
mounted to the distal end of the inner catheter and serves to ease
the passage of the delivery system through the patient's
vasculature. The system also may include some type of guidewire to
guide the delivery system to its desired implant location. Another
alternative delivery system that can be used, in particular, for
stented valves having a self-expanding stent, includes a catheter
that does not have balloons, but instead includes a sheath or other
mechanism that maintains the self-expanding stent in its compressed
condition until it is desired to allow it to expand. When such a
self-expanding stent is properly positioned in the patient, the
mechanism that keeps the stent compressed can be retracted or
otherwise removed to allow for expansion of the stent against the
vessel walls.
[0075] The delivery system and its use may correspond to that
described in the above-cited Tower, et al. applications, where the
stented valve can be expanded against a failed native or prosthetic
valve. The delivery system can be advanced to the desired valve
implant site using the guidewire, after which the sheath is moved
proximally, exposing the valve and balloon mounted on inner
catheter. The balloon is expanded, which thereby expands stented
valve 52 until it reaches a desired outer diameter where it
contacts the wall of a heart vessel. The balloon is then deflated
and the delivery system is withdrawn proximally.
[0076] The present invention has now been described with reference
to several embodiments thereof. The entire disclosure of any patent
or patent application identified herein is hereby incorporated by
reference. The foregoing detailed description and examples have
been given for clarity of understanding only. No unnecessary
limitations are to be understood therefrom. It will be apparent to
those skilled in the art that many changes can be made in the
embodiments described without departing from the scope of the
invention. Thus, the scope of the present invention should not be
limited to the structures described herein, but only by the
structures described by the language of the claims and the
equivalents of those structures.
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