NZ614392B2 - Heart valve - Google Patents
Heart valve Download PDFInfo
- Publication number
- NZ614392B2 NZ614392B2 NZ614392A NZ61439212A NZ614392B2 NZ 614392 B2 NZ614392 B2 NZ 614392B2 NZ 614392 A NZ614392 A NZ 614392A NZ 61439212 A NZ61439212 A NZ 61439212A NZ 614392 B2 NZ614392 B2 NZ 614392B2
- Authority
- NZ
- New Zealand
- Prior art keywords
- leaflet
- heart valve
- artificial heart
- attachment
- valve according
- Prior art date
Links
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- 230000017531 blood circulation Effects 0.000 claims abstract description 69
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- 239000007943 implant Substances 0.000 abstract description 3
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/24—Heart valves ; Vascular valves, e.g. venous valves; Heart implants, e.g. passive devices for improving the function of the native valve or the heart muscle; Transmyocardial revascularisation [TMR] devices; Valves implantable in the body
- A61F2/2409—Support rings therefor, e.g. for connecting valves to tissue
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/24—Heart valves ; Vascular valves, e.g. venous valves; Heart implants, e.g. passive devices for improving the function of the native valve or the heart muscle; Transmyocardial revascularisation [TMR] devices; Valves implantable in the body
- A61F2/2412—Heart valves ; Vascular valves, e.g. venous valves; Heart implants, e.g. passive devices for improving the function of the native valve or the heart muscle; Transmyocardial revascularisation [TMR] devices; Valves implantable in the body with soft flexible valve members, e.g. tissue valves shaped like natural valves
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/24—Heart valves ; Vascular valves, e.g. venous valves; Heart implants, e.g. passive devices for improving the function of the native valve or the heart muscle; Transmyocardial revascularisation [TMR] devices; Valves implantable in the body
- A61F2/2412—Heart valves ; Vascular valves, e.g. venous valves; Heart implants, e.g. passive devices for improving the function of the native valve or the heart muscle; Transmyocardial revascularisation [TMR] devices; Valves implantable in the body with soft flexible valve members, e.g. tissue valves shaped like natural valves
- A61F2/2415—Manufacturing methods
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/24—Heart valves ; Vascular valves, e.g. venous valves; Heart implants, e.g. passive devices for improving the function of the native valve or the heart muscle; Transmyocardial revascularisation [TMR] devices; Valves implantable in the body
- A61F2/2412—Heart valves ; Vascular valves, e.g. venous valves; Heart implants, e.g. passive devices for improving the function of the native valve or the heart muscle; Transmyocardial revascularisation [TMR] devices; Valves implantable in the body with soft flexible valve members, e.g. tissue valves shaped like natural valves
- A61F2/2418—Scaffolds therefor, e.g. support stents
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2220/00—Fixations or connections for prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
- A61F2220/0025—Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
- A61F2220/0033—Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2220/00—Fixations or connections for prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
- A61F2220/0025—Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
- A61F2220/0058—Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements soldered or brazed or welded
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2230/00—Geometry of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
- A61F2230/0063—Three-dimensional shapes
- A61F2230/0091—Three-dimensional shapes helically-coiled or spirally-coiled, i.e. having a 2-D spiral cross-section
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2250/00—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
- A61F2250/0058—Additional features; Implant or prostheses properties not otherwise provided for
- A61F2250/006—Additional features; Implant or prostheses properties not otherwise provided for modular
Abstract
artificial heart valve (102) is disclosed. In general, mechanical valves require life-long anticoagulant drug treatment to prevent blood clotting around the valve while biological valves are vulnerable to degeneration that limits their useful life, particularly in children and young adults. If a reasonably priced, reliable heart valve that did not require anticoagulation, and was easy to implant in a conventional operating room, were available, there would be a wide clinical application. Such a valve is disclosed. The valve comprises a support structure (106) defining an aperture for blood flow and a flexible leaflet (104) connected to the support structure along first and second at least partially straight lines of attachment (114). The leaflet is movable relative to the support structure between an open configuration in which the leaflet permits blood flow through the aperture and a closed configuration in which the leaflet restricts blood flow through the aperture. A lateral cross-section taken through the leaflet defines an outwardly convex portion (121), an outwardly concave portion (122) and a junction (118) between the convex and concave portions. The heart valve may be configured for implantation in a human or animal subject. A method of manufacturing a heart valve and a former for use in such a method are also disclosed. reasonably priced, reliable heart valve that did not require anticoagulation, and was easy to implant in a conventional operating room, were available, there would be a wide clinical application. Such a valve is disclosed. The valve comprises a support structure (106) defining an aperture for blood flow and a flexible leaflet (104) connected to the support structure along first and second at least partially straight lines of attachment (114). The leaflet is movable relative to the support structure between an open configuration in which the leaflet permits blood flow through the aperture and a closed configuration in which the leaflet restricts blood flow through the aperture. A lateral cross-section taken through the leaflet defines an outwardly convex portion (121), an outwardly concave portion (122) and a junction (118) between the convex and concave portions. The heart valve may be configured for implantation in a human or animal subject. A method of manufacturing a heart valve and a former for use in such a method are also disclosed.
Description
HEART VALVE
FIELD
The present invention relates to an artificial heart valve and a method of
manufacturing such an artificial heart valve.
BACKGROUND
The valves of the heart may be abnormal from birth, may become diseased, or
may rate in old age. When their function becomes iently impaired they
may require to be replaced. There are many different artificial heart valves available
for their replacement in established clinical use. In general, these cial valves have
been of two types. Mechanical ement heart valves are constructed of rigid,
synthetic materials such as metallic alloys, pyrolytic carbon, or rigid polymers. They do
not resemble natural heart valves. Biological replacement heart valves are constructed
of flexible materials of human or animal origin such as human aortic or pulmonary
valves, animal aortic or venous valves, or animal pericardium (the fibrous sheet
surrounding the heart). Such animal tissues are commonly treated with agents such as
glutaraldehyde to enhance their durability. ical heart valves resemble the l
aortic or pulmonary valves. Glutaraldehyde-treated bovine pericardium is a commonly
used material, fashioned into three flexible leaflets on a supporting frame to mimic the
natural aortic valve. These valves are implanted into the heart after removal of the
abnormal valve by means of an open-heart operation. More recently, flexible valve
leaflets have been attached within an expandable mesh-like cylinder for implantation
via a catheter introduced into the apex of the heart or via a peripheral blood vessel.
After manipulation into the correct location the device is ed with a balloon to
create a functional valve, without the need for conventional ve surgery.
In general, mechanical valves require life-long anticoagulant drug treatment to
prevent blood clotting around the valve and interfering with valve function, or ing
in the bloodstream to block vital es to the brain, gut. limbs or other areas, while
biological valves are vulnerable to degeneration that limits their useful life, particularly
in children and young adults.
Attempts to substitute a synthetic material for the ical material of the valve
leaflets have been stimulated by the desire to avoid the leaflet calcification and
degeneration, particularly in young adults and children, which t from the clinical
attractiveness of bioprosthetic valves. Most efforts have focussed on biostable
polyurethanes. Valve design has resembled that of bioprosthetic valves in the
expectation of retaining the low o-embolic risk of these valves.
Synthetic ric, flexible-leaflet artificial heart valves, being still at an
experimental stage, cannot be said to have a standard, established pattern of design.
However, those examples that have been revealed in the literature mimic the design of
the standard, established bioprosthetic valve, that in turn resembles the natural aortic
valve of the heart. There is a good reason for this as this design retains near natural
blood flow through the functioning valve. This is believed to be responsible for the
bioprosthetic valve being ly to activate the blood clotting mechanisms of the body
(“low thrombo-embolic risk” - hence allowing use of these valves t the clinical
need for anticoagulation), in contrast to the “unnatural” design and abnormal flow
patterns of mechanical valves.
The use of synthetic polymers, such as polyurethane, has been proposed as a
possible solution to the limited durability of current flexible-leaflet bioprosthetic heart
valves of animal origin. There are few examples of synthetic polymer heart valves in
al use and these are currently confined to use in extracorporeal circuits where
prolonged function is not required. Experimental polymer heart valves have shown
limited durability and this is a serious disincentive to further development of such
valves for clinical use as valve replacement devices, mental polymer heart
valves have, in particular, been susceptible to damage such as tearing as a
consequence of high localised bending stresses ally caused by buckling or
wrinkling that may occur during valve operation.
The available polyurethanes that are suitable for medical use and that are
sufficiently biostable for prolonged use in the bloodstream are relatively limited in
number and are generally too stiff to allow satisfactory function of leaflets made from
ethanes. This is ularly nt with the stiffer, higher modulus,
polyurethanes that would have greatest durability and bility. rmore, the
use of reinforcement within the polyurethane, such as carbon nanotubes or larger
fibres, is likely to increase stiffness and render the reinforced leaflet too stiff for
satisfactory haemodynamic function i.e. too stiff to allow the valve to open and close
readily with actory pressure drop across the valve and low regurgitation through
the valve.
An important group of patients at present have no cal, satisfactory
ement heart valve available to them. This group comprises children and young
adults in the developing nations. For e, Sub-Saharan Africa has the largest
population of rheumatic heart disease patients in the world (World Health Organisation
(WHO) estimates over 1 million aged 5—24 year olds — compared to some 33,000 in
the industrialised world). Many of these go on to merit valve replacement. For these
young patients the complex valve repair or valve transfer (Ross ion) procedures.
sometimes applicable in the developed world, are not a feasible prospect; mechanical
valves need life-long anticoagulant therapy f needing supervision), with a
prohibitive life-long risk of bleeding or valve thrombosis; and biological valves often last
only a few years before needing repeat y, with its own attendant risks. Thus, for
1O the relatively small number of younger patients in the rialised world, and for
patients who cannot take anticoagulant drugs for medical or life-style reasons there is a
pressing need for a durable replacement heart valve that will function clinically
satisfactorily without anticoagulant drugs for many years without being vulnerable to
early deterioration and failure. r, there is a very much larger population of
patients in the ping world who could benefit from such a valve. Access to
surgical facilities has often been a limiting factor, but with sing development in
many countries this may well become less of a problem. If a reasonably priced,
reliable heart valve that did not require anticoagulation, and was easy to implant in a
tional operating room, were available, there would be a wide clinical application.
In this specification, the term ‘comprises’ and its variants are not intended to
exclude the presence of other integers, components or steps.
In this specification, references to prior art are not intended to acknowledge or
suggest that such prior art is widely known or forms part of the common general
knowledge in the field either in New Zealand or elsewhere
SUMMARY
According to a first aspect of the present invention there is provided an artificial
heart valve comprising a support structure defining an aperture for blood flow and a
flexible leaflet which is movable relative to the support structure between an open
configuration in which the leaflet permits blood flow through the aperture and a closed
configuration in which the leaflet cts blood flow h the aperture,
wherein the aperture defines an axis, and a l cross-section taken through
the leaflet in a plane lateral to the axis defines an outwardly convex n, an
outwardly concave portion and a junction between the convex and concave portions
when the leaflet is in the open and closed configurations and all t configurations
intermediate the open and closed configurations including a natural or default
configuration in which the leaflet is , and
wherein the leaflet is attached to the support structure along first and second at
least partially straight lines of attachment such that movement of the leaflet between
the open and closed configurations results in the convex portion of the lateral cross-
section pivoting about one of the first and second lines of attachment and the e
portion of the lateral cross-section pivoting about the other of the first and second lines
of attachment.
In use, such a valve may be implanted into a human or animal such that the
leaflet extends along a direction of blood flow and the l cross-section through the
leaflet is aligned so as to be generally lateral to the direction of blood flow.
The valve may be configured for connection to a human or animal, for example,
to a heart of a human or animal or to a blood vessel adjacent to a heart of a human or
animal.
The valve may be configured for connection to a heart by sewing, ng,
stitching or the like.
The valve may be configured to be implanted, welded, adhered or otherwise
attached to a heart.
The leaflet may be e n the open and closed configurations in
response to a change in pressure across the t.
Such a heart valve may permit blood flow through the valve in a fonNard
direction when the leaflet is in the open configuration and may restrict or prevent blood
flow through the valve in a backward direction when the t is in the closed
configuration.
The valve may be formed so as to have a natural configuration.
The valve may be unstressed or have minimal internal es in the natural
configuration.
The valve may have a default configuration which corresponds to the natural
uration.
The valve may be configured such that the leaflet returns to the default
configuration in the absence of any pressure differential across the leaflet.
The arrangement of the leaflet in the default configuration may be intermediate
the arrangement of the leaflet in the open and closed configurations.
The leaflet may have a lateral cross—section which defines an outwardly convex
portion, an dly concave portion and a junction between the convex and concave
portions in the open configuration, in the closed configuration and in all intermediate
configurations between the open and closed configurations including the default
configuration.
The valve may be configured to permit movement of the leaflet from the default
configuration to the closed configuration in se to an riate pressure
ential.
The valve may be configured to permit movement of the leaflet from the default
configuration to the open configuration in response to an appropriate pressure
differential.
The valve may be ured such that the leaflet readily moves from the
default configuration to the open configuration in response to an appropriate pressure
differential.
At least one of the junction, the convex portion and the concave portion may
vary according to a pressure differential across the leaflet.
ht or at least partially straight first and second lines of attachment and the
configuration of the lateral cross-section h the leaflet may ensure that the leaflet
is le between the open and closed configurations ing to a preferential
mode of movement in which changes in ure of the leaflet are distributed across
the whole width of the leaflet, and not primarily by changes close to the lines of
attachment of the leaflet to the support ure, as is the case for many conventional
designs of bloprosthetlc and tic flexible leaflet valves. Such a mode of
movement may ensure that the t is moveable between the open and closed
configurations whilst inducing lower bending stresses in the leaflet compared with the
bending stresses induced in known artificial heart valves. For a given leaflet stiffness,
this may reduce the bending stresses induced in the leaflet during operation of the
heart valve and thereby reduce the susceptibility of the leaflet to damage such as
g, cracking or the like. Thus, for a given leaflet stiffness, this may lead to
improved reliability of the heart valve.
Straight or at least partially straight first and second lines of attachment and the
configuration of the lateral cross-section through the leaflet may ensure that the leaflet
adopts a shape which provides a d restriction to fluid flow when the leaflet is in
the open configuration compared with known bioprosthetic heart valves or known
synthetic leaflet heart valves. Consequently, such a heart valve may have improved
haemodynamic performance for a given leaflet stiffness. Alternatively, for a given
haemodynamic performance, such a heart valve may be constructed using a stiffer
t. For example. a stiffer leaflet material may be selected and/or the thickness of
the leaflet may be increased t compromising haemodynamic performance
relative to the haemodynamic performance of known bioprosthetic heart valves or
known synthetic leaflet heart valves. This may, in particular, permit the use of stiffer
higher modulus leaflet materials having greater durability and greater biostability
without compromising haemodynamic performance.
Straight or at least partially straight first and second lines of attachment and the
configuration of the lateral cross-section h the leaflet may ensure that the leaflet
adopts a predetermined shape in response to a given pressure differential across the
leaflets. More ically, the convex and lly concave portions may vary in a
predetermined manner in response to s in pressure differential across the
leaflets. This may t the leaflet from adopting an arbitrary shape during
reconfiguration between the open and closed configurations and may, in particular,
avoid acute bending, ng or wrinkling of the leaflet during reconfiguration. For a
given leaflet stiffness, this may reduce the bending stresses induced in the leaflet
during operation of the heart valve and thereby reduce the susceptibility of the t to
damage such as tearing, cracking or the like. Thus, for a given leaflet stiffness, this
may lead to improved reliability of the heart valve.
The first and second lines of attachment may be generally parallel.
The first and second lines of attachment may extend in a direction which is
generally parallel to the axis.
The convex portion may extend from the first line of attachment to the junction.
The concave n may extend from the second line of ment to the
junction.
The lateral section may have a curvature which is discontinuous at the
junction.
The lateral cross-section may have a curvature which is continuous at the
junction.
The junction may comprise a region of inflection.
The junction may comprise a point of inflection.
The junction may comprise a curved region.
The junction may comprise a straight region.
The configuration of the lateral cross-section of the leaflet may ensure that the
leaflet adopts a predetermined shape which provides improved blood flow
characteristics. The configuration of the lateral cross—section of the leaflet may impart
a spiral motion to the blood passing through the valve, such that the blood flow through
the valve mimics physiological blood flow conditions through a natural heart valve more
accurately when compared to known cial heart valve arrangements. Such a spiral
blood flow may improve the ency of the heart compared with the efficiency of the
heart when using a known artificial heart valve.
The leaflet may be configured to define a lateral cross-section which imparts a
spiral blood flow in a counter-clockwise direction when viewed from an w side of
the valve. The lateral cross-section through the t may define the outwardly
convex portion followed by the outwardly concave portion in a generally counter-
‘IO ise direction about the axis defined by the aperture when viewed from the
outflow side of the valve.
The leaflet may be configured to define a lateral section which imparts a
spiral blood flow in a clockwise direction when viewed from the outflow side of the
valve. The lateral cross-section through the leaflet may define the outwardly concave
portion followed by the outwardly convex portion in a generally counter-clockwise
direction about the axis defined by the aperture when viewed from the outflow side of
the valve.
The artificial heart valve may be configured such that movement of the leaflet
between the open and closed configurations results in the convex portion of the lateral
cross-section pivoting about the first line of attachment.
The artificial heart valve may be configured such that movement of the leaflet
n the open and closed urations results in the concave portion of the lateral
cross-section pivoting about the second line of ment.
The artificial heart valve may be configured such that movement of the leaflet
results in a change in curvature of the convex and concave portions of the l
section.
The artificial heart valve may be configured such that movement of the leaflet
away from the closed configuration towards the open configuration results in a
reduction in curvature of the convex portion of the lateral cross-section.
3O The artificial heart valve may be configured such that movement of the leaflet
away from the closed configuration towards the open configuration results in an
increase in curvature of the concave portion of the lateral cross-section.
The artificial heart valve may be configured such that nt of the leaflet
from the closed configuration to the open uration results in an initial increase in
ure of the convex and concave portions of the lateral cross-section of the leaflet
followed by a decrease in curvature of the convex portion and a further increase in
curvature of the concave portion.
The artificial heart valve may be configured such that movement of the leaflet
results in nt of the junction along the lateral cross-section of the leaflet.
The artificial heart valve may be configured such that movement of the t
away from the closed configuration s the open uration results in movement
of the junction along the lateral cross-section of the leaflet away from the first line of
ment towards the second line of attachment.
The artificial heart valve may be ured such that movement of the leaflet
from the closed configuration to the open configuration results initially in no movement
of the junction along the lateral cross-section of the leaflet followed by movement of the
junction along the lateral cross-section of the leaflet from the first line of attachment
towards the second line of ment.
A length of the convex portion of the lateral cross-section may comprise a
greater tion of a total length of the l cross-section in the open configuration
than in the closed configuration.
The leaflet may be ted to the support structure along a base line of
attachment.
The base line of attachment may extend at least partially around the aperture.
The base line of attachment may extend circumferentially around the aperture.
The base line of attachment may be adjacent to the aperture.
The base line of attachment may be outwardly convex.
The leaflet may comprise a free edge which is movable relative to the support
structure.
The free edge may extend te the base line of attachment between the
first and second lines of attachment.
The free edge may define an dly convex portion, an outwardly concave
portion and a junction between the convex and concave portions.
The junction of the free edge may be located substantially half-way along the
3O free edge between the first and second lines of attachment.
The free edge of the leaflet may be longer than the base line of attachment.
Each of a plurality of lateral cross-sections taken through the leaflet between
the base line of attachment and the free edge may define an outwardly convex portion,
an outwardly concave portion and a junction between the convex and concave
portions.
The leaflet may define a ation region which extends from the free edge
and which has a plurality of generally identical l cross-sections.
A inwardly disposed e of such a co-aptation region may form an improved
seal against a complementary inwardly disposed e of a further co—aptation
region, for example an inwardly disposed co-aptation region of a further t, to
prevent or reduce back flow of blood through the aperture when the leaflet is in the
closed configuration.
The co-aptation region may extend from the free edge to a boundary which is
located between the free edge and the base line of attachment
A lateral cross-section which is closer to the base line of attachment but
n the base line of attachment and the boundary of the co-aptation region may
have a longer convex portion and a shorter concave portion than a lateral cross-section
which is further from the base line of attachment but between the base line of
attachment and the boundary of the co-aptation region.
The junction of each of the lateral cross—sections taken through the leaflet
between the base line of attachment and the boundary of the co-aptation region may lie
along a pre-determined junction reference line when the leaflet is in an as—formed or
natural configuration.
The junction reference line may be at least partially straight.
The junction reference line may extend from a point substantially ay along
the boundary of the co—aptation region to a point of ection between the second
line of attachment and the base line of attachment. Such an arrangement may ensure
that the leaflet in its as-formed or natural configuration defines a three-dimensional
lly conical region having an apex located at or nt the point of intersection
of the second line of attachment with the base line of attachment. Such a three-
dimensional leaflet shape may serve to distribute stresses across the width of the
leaflet during movement of the leaflet n the open and closed configurations.
The support structure may comprise a base n that defines the aperture.
The base portion may be curved. The base portion may comprise a loop or be
generally annular. The base portion may be circular, oval or the like.
The base portion may be configured for attachment to a human or animal, for
example. to a heart of a human or animal or to a blood vessel adjacent to a heart of a
human or animal. The base portion may be configured to be implanted, sutured,
welded, adhered or ise attached to a human or animal.
The aperture may be curved. The aperture may be circular, oval or the like.
The leaflet may be connected to the base portion along a base line of
attachment.
The support structure may comprise a plurality of post portions extending from
the base portion.
The plurality of post portions may be arranged around the aperture.
Each post portion may extend in a generally axial direction.
Each post portion may comprise a straight edge which extends in a generally
axial direction. For example, the base portion may define a l plane and the
straight edge of each post portion may extend in a direction perpendicular to the lateral
1O plane of the base portion.
The support structure may se first and second post portions which define
the first and second lines of attachment.
The leaflet may be attached between two post portions.
The leaflet may be ed between two adjacent post portions.
The valve may be configured such that a on of a free edge of the leaflet
lies to one side of a straight line between the two posts to which the leaflet is attached
when the leaflet is in a closed configuration. The valve may be configured such that
the junction of the free edge of the leaflet lies to the other side of the straight line
between the two posts to which the leaflet is attached when the leaflet is in an open
configuration.
Such a configuration may result in exertion of a compressive force on the t
as the leaflet passes between the two posts during nt of the leaflet between
open and closed configurations. Such a ssive force may accentuate a
curvature of the convex and concave portions of a lateral cross-section of the leaflet as
the leaflet passes between the two posts.
The post portions may extend from the base portion in an dly splayed
configuration. Each post portion may define an acute angle with respect to the axial
direction. Each post portion may define an angle with respect to the axial direction of
between 0 and 30°, between 0 and 10°. or between 0 and 5°. Such an dly
3O splayed uration of the post portions may permit the leaflet to move between the
open and closed configurations more easily. This may reduce stress induced in the
leaflet during movement thereof.
The leaflet may extend through and around the first post portion along the first
line of attachment.
The leaflet may extend through and around the second post portion along the
second line of attachment.
The first and second post ns may each define a hole which extends
therethrough.
The leaflet may extend through the hole which extends through the first post
portion along the first line of attachment.
The leaflet may extend through the hole which extends through the second post
portion along the second line of attachment.
Such an arrangement may serve to provide a robust anchor between the leaflet
and each of the first and second post ns.
The respective holes which extend through the first and second post portions
may be angled with respect to a radial direction relative to the axis defined by the
aperture. This may ensure that the leaflet enters and/or exits the respective holes
which extend through the first and second post portions with a predetermined
uration such as a predetermined angle. Such an angle may ensure that a lateral
cross-section of the leaflet as the leaflet emerges from the respective holes extending
through the first or second post portion has a curvature which is continuous with a
curvature of an outwardly convex or an outwardly concave portion of the l cross—
section of the leaflet adjacent to the first or second post portion.
The holes which extend through the first and second post portions may each be
ted. For example, the holes which extend through the first and second post
portions may each se a slit or the like.
The first and second post portions may each define a plurality of holes
extending therethrough.
The t may extend through each of the plurality of holes extending through
the first and second post portions.
The leaflet may be connected to the base portion along a base line of
attachment.
The leaflet may extend h and around the base portion.
The base portion may define a hole which extends therethrough.
The leaflet may extend through the hole defined by the base portion.
Such an arrangement may serve to provide a robust anchor between the leaflet
and the base portion.
The one or more holes which extend through the base portion may be angled
with respect to a radial direction relative to the axis d by the aperture.
This may ensure that the leaflet enters and/or exits the one or more holes which
extend through the base n with a predetermined configuration such as a
predetermined angle. Such an angle may ensure that a lateral cross-section of the
leaflet as the leaflet emerges from the one or more holes ing through the base
portion has a curvature which is continuous with a curvature of the leaflet adjacent to
the base portion.
The one or more holes which extend through the base portion may be
ted. For example, the one or more holes which extend through the base portion
may comprise slits or the like.
The base portion may define a plurality of holes extending therethrough.
The leaflet may extend through the plurality of holes defined by the base
portion.
The leaflet may be integrally formed on the t structure.
The leaflet may se a synthetic material.
The leaflet may comprise a polymeric material.
The leaflet may comprise polyurethane.
The leaflet may comprise a composite material including a matrix material and
one or more reinforcing elements. For example, the t may comprise a matrix
material and one or more reinforcing ts such as fibres, s, strands,
nanotubes or the like.
The leaflet may comprise polyurethane reinforced with carbon nanotubes.
The heart valve may comprise a plurality of flexible leaflets, each leaflet being
connected to the support structure along corresponding first and second lines of
attachment such that each leaflet is movable relative to the support structure between
an open configuration in which the leaflet permits blood flow through the aperture and a
closed configuration in which the leaflet cts blood flow through the aperture,
wherein a lateral cross-section taken through each leaflet in a plane lateral to the axis
defines a corresponding outwardly convex portion, a corresponding outwardly concave
portion and a corresponding junction between the convex and concave portions.
The curvature of a convex portion of a first leaflet may be substantially d
to the curvature of a e portion of a second leaflet adjacent to the first leaflet in a
l cross-section taken through the first and second leaflets.
Such a valve may ensure that each leaflet at least partially es blood flow
h the valve when the leaflets are configured in the closed configuration.
Each leaflet may define a co—aptation surface which is configured to engage
one or more complementary co-aptation surfaces of one or more other leaflets. Such
co-aptation surfaces may form an improved seal to prevent or reduce back flow of
blood through the aperture when the leaflets are in the closed configuration.
Each post n may have a plurality of leaflets attached thereto.
Each leaflet may be integrally formed on the frame.
The valve may comprise three leaflets.
The valve may comprise three posts.
Such a valve may provide a eses for the ventriculo-arteriai valves (aortic
and ary).
The valve may comprise two leaflets.
The valve may comprise two posts.
Such a valve may provide a prostheses for the atrio-ventricular valves (mitral
and tricuspid).
At least a portion of the t structure may be rigid or semi-rigid.
At least a portion of the support structure may be flexible. For e, at least
a portion of the support structure may be expandable.
Such a support ure may permit the valve to be compressed or collapsed
for insertion into a subject’s body, for example, via a blood vessel. Such a support
structure may permit the valve to expand in situ over a timescale to accommodate
growth of the subject.
Such a support structure may also accommodate growth of a subject such as a
child.
The support structure may comprise a material which is stiffer than a material of
the leaflet.
The support structure may comprise a metal.
The support structure may comprise stainless steel.
The support ure may comprise titanium.
The support structure may comprise a polymer such as polyether ether ketone
(PEEK) or the like.
At least a portion of the support structure may be flexible or sible.
The support structure may comprise a frame.
The support ure may have a rounded profile. For example, the t
structure may have rounded corners. Such a support structure should reduce the risks
of injury to a human or an animal subject during deployment or implantation of the
heart valve into a human or animal subject.
The valve may be configured for percutaneous delivery.
The support structure may se a stent.
The support ure may comprise a portion of a heart. In other words, the
leaflet may be configured for direct attachment to the heart ofa human or an animal.
The valve may comprise first and second inter-engageable parts.
The first part may be configured for connection to a human or animal, for
example, to a heart of a human or animal or to a blood vessel adjacent to a heart of a
1O human or animal.
The second part may comprise the leaflet
. The use of such first and second
parts may permit the first part to be attached to a heart t risk of damage to a
leaflet of the second part.
The first part may be configured for connection to a heart by sewing, ng,
stitching or the like.
The first part may be configured to be implanted, welded, adhered or otherwise
attached to a heart.
The first part may be curved. The first part may comprise a loop or be generally
annular. The first part may be circular, oval or the like.
The first part may comprise a sewing ring.
The first part may be configured for connection to a heart by passing thread,
wire or the like around the first part and into a wall of a heart.
The first and second parts may comprise complementary inter-engaging
features.
The first and second parts may comprise male and female features.
One of the first and second parts may comprise one or more projections and
the other of the first and second parts may comprise one or more recesses, wherein
each recess is ured to receive a projection.
The first and second parts may be configured to provide a lockable connection
with one another. For example, one of the first and second parts may comprise a
bayonet and the other of the first and second parts may comprise a socket configured
to e the bayonet. The bayonet may be ured for locking within the socket by
ng the first and/or second parts relative to one another.
The support structure may comprise a third part such as an adapter part for
facilitating a connection between the first and second parts.
According to a second aspect of the present invention there is provided artificial
heart valve comprising a support structure ng an re for blood flow and a
flexible leaflet connected to the support structure along first and second lines of
ment, wherein the t is movable relative to the support structure between an
open configuration in which the leaflet permits blood flow through the re and a
closed configuration in which the t restricts blood flow through the aperture, and
n the aperture defines an axis and a lateral cross-section taken through the
leaflet in a plane lateral to the axis defines an outwardly convex portion extending from
the first line of attachment to a junction and an outwardly concave portion extending
from the junction to the second line of attachment.
The first and second lines of ment may be at least partially straight.
The first and second lines of attachment may have a generally parallel
relationship.
The first and second lines of ment may extend at least lly in a
direction parallel to the axis defined by the aperture.
The first and second lines of attachment may be at least partially curved.
It should be understood that one or more of the optional features described in
relation to the first aspect may apply alone or in any combination in relation to the
second aspect.
According to a third aspect of the present invention there is provided artificial
heart valve comprising a support structure and an integrally formed flexible leaflet,
wherein the support ure defines an aperture for blood flow and a through hole and
the leaflet extends through the through hole and around a portion of the support
structure.
The t may be integrally formed so as to extend through the through hole.
The leaflet may be integrally formed so as to extend around a portion of the
support structure adjacent to the through hole.
Such an arrangement may serve to provide a robust anchor between the leaflet
and the support structure.
The through hole may be elongated.
The through hole may comprise a slit or the like.
The through hole may be angled. Such a through hole may serve to ensure
that the leaflet enters and/or exits the hole with a predetermined configuration such as
a predetermined angle.
The support structure may define a plurality of through holes extending
therethrough.
The leaflet may be integrally formed so as to extend through each of the
plurality of through holes.
The leaflet may be integrally formed so as to extend around a portion of the
support structure adjacent to each of the plurality of through holes.
Each of the plurality of through holes may be elongated.
Each of the plurality of through holes may comprise a slit or the like.
It should be understood that one or more of the optional features described in
relation to the first aspect may apply alone or in any combination in relation to the third
aspect.
According to a fourth aspect of the t invention there is provided an
artificial heart valve comprising a support structure and a flexible leaflet connected to
the support structure, each leaflet being formed so as to provide a predetermined
shape throughout movement of the leaflet between open and closed configurations.
The leaflet may be formed so as to comprise a lateral cross-section which
s an outwardly convex portion, an outwardly concave portion and a junction
between the convex and concave portions.
Such a leaflet may ensure that the convex and e portions move in a
predetermined manner in se to changes in re differential across the
leaflet so as to avoid buckling of the leaflet.
In use, such a valve may be implanted into a human or animal subject such that
the leaflet extends along a direction of blood flow and the lateral cross-section through
the leaflet is aligned so as to be generally lateral to the direction of blood flow.
The heart valve may comprise a plurality of flexible leaflets, n each leaflet
is connected to the support structure.
it should be tood that one or more of the optional features described in
relation to the first aspect may apply alone or in any combination in relation to the
fourth aspect.
According to a fifth aspect of the t invention there is provided a method
of implanting an artificial heart valve comprising:
providing an artificial heart valve sing a support structure defining an
re for blood flow and a flexible leaflet ted to the support structure along
first and second at least partially straight lines of attachment, wherein the leaflet is
movable relative to the support structure between an open configuration in which the
leaflet permits blood flow through the aperture and a closed configuration in which the
leaflet restricts blood flow through the aperture, and wherein the re defines an
axis and a lateral cross—section taken h the leaflet in a plane lateral to the axis
defines an outwardly convex portion, an outwardly concave portion and a on
between the convex and concave portions; and
implanting the artificial heart valve into a subject such that the axis defined by
the aperture extends along a direction of blood flow.
It should be understood that one or more of the optional features described in
relation to the first aspect may apply alone or in any combination in relation to the fifth
aspect.
According to a sixth aspect of the present invention there is provided a leaflet
for an artificial heart valve of the first aspect comprising first and second ends which
are configured for attachment to the support structure along the first and second lines
of attachment respectively.
It should be understood that one or more of the optional features described in
relation to the first aspect may apply alone or in any combination in relation to the sixth
aspect.
According to a seventh aspect of the present invention there is provided a
method of manufacturing an artificial heart valve comprising:
attaching a flexible leaflet to a t structure along first and second at least
partially straightlines of attachment, such that the leaflet is movable relative to the
support structure between an open uration in which the leaflet permits blood flow
through an aperture defined by the support structure and a closed configuration in
which the leaflet restricts blood flow through the aperture, wherein the re defines
an axis and a lateral cross-section taken through the leaflet in a plane lateral to the axis
defines an dly convex portion, an outwardly concave portion and a junction
n the convex and concave portions when the leaflet is in the open and closed
configurations and all leaflet configurations intermediate the open and closed
configurations including a natural or default uration in which the leaflet is formed,
and such that movement of the t between the open and closed urations
results in the convex portion of the l cross-section pivoting about one of the first
and second lines of attachment and the concave portion of the lateral cross-section
pivoting about the other of the first and second lines of attachment.
The method may comprise dip—coating the t structure in a liquid.
The method may comprise permitting or causing the liquid to fy so as to
define the flexible leaflet.
The method may comprise:
mounting the support structure on a former prior to dip-coating the support
structure in the liquid; and
removing the support structure and the flexible leaflet from the former after
solidification of the liquid.
The former may comprise an outer surface on which the liquid solidifies so as to
define the flexible leaflet.
The outer surface may be ured to define the flexible leaflet of any of the
heart valves of the first to fourth aspects on solidification of a liquid thereon.
The former may comprise a base portion for ing a base portion of the
support structure and a mandrel n having the outer e on which the liquid
solidifies so as to define the flexible leaflet.
The method may se dipping the former with the support structure
mounted thereon in the liquid so as to coat the outer surface of the former between the
third edge and a lateral upper co-aptation plane located between the l lower co-
aptation plane and the fourth edge.
The method may comprise trimming the leaflet across the co-aptation surface of
the leaflet after solidification of the liquid so as to define a free edge of the leaflet.
The outer surface of the former may be configured to suppress adhesion of the liquid to
the outer surface.
The liquid may comprise a molten material.
The liquid may se a synthetic material.
The liquid may comprise a polymeric material.
The liquid may comprise polyurethane.
The liquid may comprise a on.
The liquid may comprise a ethane solution.
Such a method may ensure the integral formation and secure ment of the
leaflet to the support structure by encasing the support structure with a continuous
sheet of the liquid prior to drying. This has the advantage that leaflet attachment is not
limited to adhesion of the liquid material to one or more portions of the support
structure thus reducing the risk of the leaflet becoming detached from the support
structure, for example, during implantation or operation of the valve.
The method may comprise aligning the support structure and a former relative
to one another.
The method may comprise dip-coating the support structure and the former
together as an assembly in the liquid.
The method may comprise permitting or causing the liquid to fy or dry on
the former and removing the former after fication of the liquid.
Such a former may permit the ion of the le leaflets and, in particular,
permit the formation of the flexible leaflets having free edges which are movable
relative to the support structure.
The method may comprise ing the support structure and the former with
the same or corresponding alignment features to permit the support ure and the
former to be aligned relative to one another. For example, the method may comprise
providing the support structure and the former with complementary inter-engaging
features.
The method may comprise ing the former with one alignment feature for
every post portion of the support structure, and providing each post portion of the
support structure with an alignment e configured for alignment and/or
engagement with a ent alignment feature of the former.
The method may comprise providing each post portion of the support structure
with a longitudinal re such as a slot, slit or the like.
The method may comprise providing each post portion of the support structure
with a longitudinal recess such as a groove or the like.
The method may comprise providing the former with one longitudinal tion
for each post portion of the support structure, wherein each longitudinal projection is
configured for alignment or engagement with a longitudinal aperture or recess of a
different post portion.
Such a method may permit a slit formed in a post portion of a support ure
to be aligned with an edge of the former thus ensuring that leaflets formed on dipcoating
the support structure extend around a post portion and through the slit formed
therein for secure attachment thereto.
The method may comprise attaching the support structure and the former.
Such a step may ensure that a relative alignment between the support structure
and the former is maintained during dip-coating.
The method may comprise providing the support structure and/or the former
with the same or correSponding features to permit the support structure and the former
to be attached to one another. The method may, in particular, comprise ing the
support structure with a clearance hole for a locating pin or fastener such as a screw
fastener and providing the former with a ponding hole, such as a threaded hole,
for ing the locating pin or fastener.
The method may comprise ing a release fluid through a h-hole
which extends longitudinally through the former.
The method may se preventing liquid from solidifying or drying over a
first end of the through-hole. Injecting a fluid through the through-hole may aid release
of the artificial heart valve from the former once the liquid from which the ts are
formed has solidified or dried over a second end of the release hole opposite to the first
end of the through-hole.
The method may comprise injecting a liquid release fluid such as water, saline
or the like through the through-hole.
The method may comprise injecting a gaseous release fluid such as air or the
like through the through-hole.
The method may comprise using a syringe to inject a e fluid through the
through-hole.
Such a method may result in the formation of each leaflet and the attachment
thereof to the base portion along a base edge of the leaflet. Such a method may result
in the formation of each leaflet such that the free edge is longer than the base edge.
Such a method may result in the formation of each leaflet such that each leaflet
is ed between two post ns of a support structure.
Such a method may result in the formation of each leaflet such that each leaflet
is attached to a post portion of a support structure along a side edge of the leaflet.
Such a method may result in the formation of each leaflet such that each post
portion of a support structure may have a plurality of leaflets attached thereto.
The former may define a through-hole extending therethrough which is
configured to receive an occluding member.
The method may comprise:
occluding the through-hole with the occluding member prior to dipping the
former in the liquid so as to t ingress of the liquid into the through-hole;
removing the occluding member from the through-hole after solidification of the
liquid; and
injecting a release fluid to aid separation of the solidified liquid from the outer
surface of the mandrel portion of the former.
It should be understood that one or more of the optional features described in
relation to the first aspect may apply alone or in any combination in relation to the
seventh aspect. According to an eighth aspect of the t invention there is
provided a former for use in manufacturing an artificial heart valve comprising an outer
surface having first and second at least partially straight edges, wherein a lateral cross-
n taken h the outer surface in a plane l to the first and second edges
defines an outwardly convex portion, an outwardly concave portion and a junction
between the convex and concave portions
Such a former may be used for the manufacture of an artificial heart valve
according to any of the first to fourth aspects of the present invention or for the
manufacture of a leaflet for an artificial heart valve according to the sixth aspect. or for
use in the method of manufacturing an artificial heart valve according to the seventh
aspect.
The outer surface may be configured to permit solidification or drying of a liquid
thereon during dip-moulding.
The outer surface may be configured to suppress adhesion of the liquid to the
outer surface during dip-moulding.
The outer surface may be coated with a non-stick material.
The outer surface may be ed.
The outer e may comprise stainless steel.
The former may be ured to e a support structure of an artificial heart
valve.
The former may be configured to permit alignment of the support structure with
the former.
The former may be configured to permit attachment of the support ure to
the former.
The former may comprise a base portion for receiving a base portion of the
support structure and a mandrel portion comprising the outer surface on which the
liquid solidifies so as to define the flexible leaflet.
The outer surface may comprise a third edge adjacent the base portion of the
former and a fourth edge opposite the third edge.
Each of a plurality of l cross-sections taken through the outer surface of
the former between the third edge and the fourth edge may define an outwardly convex
portion extending from the first edge to a junction and an outwardly concave portion
extending from the second edge to the junction.
The former may comprise a through-hole extending therethrough.
The through-hole may be configured to receive an occluding member to prevent
ingress of the liquid into the h-hole during dip-moulding.
The through-hole may be configured to receive a release fluid to aid separation
of the solidified or dried liquid from the outer surface after ulding.
The h-hole may be configured to e a liquid release fluid such as
water, saline or the like.
The through-hole may be configured to receive a gaseous release fluid such as
air or the like.
The through-hole may be configured to receive pressurised release fluid.
The through-hole may be configured to receive a syringe containing the release
fluid.
The liquid may comprise a molten material.
The liquid may comprise a synthetic material.
The liquid may comprise a ric material.
The liquid may comprise polyurethane.
The liquid may comprise a solution.
The liquid may comprise a polyurethane solution.
It should be understood that one or more of the optional features bed in
2O relation to the first aspect may apply alone or in any combination in relation to the
eighth .
According to an ninth aspect of the t invention there is provided a
method for use in implanting an artificial heart valve into a human or animal subject
comprising:
sewing an attachment ring to a passageway within a human or animal subject
by looping a length of suture around at least a portion of an annular base portion of the
attachment ring.
The method may comprise using a continuous length of suture and repeatedly
looping the suture around the annular base portion. The use of such a running suture
may fy the sewing process.
Such a method may permit the use of an attachment ring having a base portion
of smaller radial extent compared with known sewing rings which have a base portion
of greater radial extent to permit attachment by sewing to a passageway within a
human or animal subject by passing sutures h the base portion. Using a base
portion of smaller radial extent may permit use of the attachment ring with an cial
heart valve having a greater aperture for blood flow.
An outer e of the attachment ring may be configured to sealingly engage
an inner surface of the passageway.
The method may comprise holding an artificial heart valve in sealing
ment with the attachment ring so as to provide a sealed periphery around a
blood flow path which extends through the attachment ring and the heart valve.
According to a tenth aspect of the present ion there is provided an
attachment ring for use in implanting an artificial heart valve into a human or animal
subject, the attachment ring comprising an annular base portion, wherein the
attachment ring is configured to be sewn to a eway within a human or animal
subject by looping a length of suture around at least a portion of the base portion.
An outer e of the attachment ring may be configured to giy engage
an inner surface of the passageway.
The attachment ring may be configured to be held in engagement with an
artificial heart valve so as to provide a sealed periphery around a blood flow path which
extends h the heart valve and the attachment ring.
The attachment ring may be configured for engagement with the heart valve so
that an inner surface of the attachment ring is held in sealing engagement with an outer
surface of the heart valve.
The base portion may have a radial extent of between 0 and 3 mm, of between
0 and 2 mm, or of between 0 and 1 mm. This may permit use of the attachment ring
with an cial heart valve having a greater aperture for blood flow.
The base portion may comprise an annular t structure which is
configured to prevent passage of a surgical needle therethrough during surgery. in
contrast, known sewing rings comprise an annular support structure which is
configured to permit passage of a surgical needle therethrough during surgery.
The support structure may comprise a metal, stainless steel. titanium, a
polymer and/or polyether ether ketone (PEEK).
3O The attachment ring may comprise a resiliently deformable cover material which
extends around at least a portion of the support structure.
The cover material may comprises Dacron.
The ment ring may comprise an engagement feature for engaging a
complementary feature of an artificial heart valve.
The attachment ring may define an aperture which s an axial direction
and the engagement feature may be ured to permit engagement with a
complementary feature of an artificial heart valve along the axial ion.
The engagement feature may extend along the axial direction. This may
simplify engagement of an artificial heart valve with the attachment ring during surgery,
for example, within the confines of a eway.
The engagement feature may have a non-circularly ric cross-section, for
example a generally square or rectangular cross-section. This may ensure that
engagement of the artificial heart valve and the attachment ring when in the correct
relative alignment.
The engagement feature may be a female engagement feature.
The engagement feature may be a male engagement feature.
The ment feature may be configured for locking engagement with a
complementary feature of an artificial heart valve.
The engagement feature may be ured to resiliently deform on
engagement with a complementary more rigid feature of an artificial heart valve.
The engagement feature may be ured to be rigid so as to cause resilient
ation of a complementary feature of an artificial heart valve on engagement
therewith.
The attachment ring may comprise a plurality of engagement features for
engaging a plurality of complementary features of an artificial heart valve.
According to an eleventh aspect of the present invention there is provided an
artificial heart valve configured to be held in sealing engagement with the attachment
ring according to the tenth aspect so as to provide a sealed periphery around a blood
flow path which extends through the heart valve and the attachment ring.
According to an twelfth aspect of the present invention there is provided an
artificial heart valve assembly comprising the attachment ring ing to the tenth
aspect in engagement with an cial heart valve according to eleventh aspect.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be described by way of non-limiting example
only with nce to the following drawings of which:
Figure 1(a) is a cut-away perspective view of a natural aortic valve with part of the
aortic valve and one leaflet removed;
Figure 1(b) is a view from an outflow side of the natural aortic valve of Figure 1(a) in
a closed configuration;
Figure 1(c) is a longitudinal cross-section of the natural aortic valve of Figure 1(a) in
a closed configuration;
Figure 1(d) is a view from an outflow side of the natural aortic valve of Figure 1(a) in
an open configuration;
Figure 1(a) is a longitudinal cross-section of the natural aortic valve of Figure 1(a) in
an open uration showing a direction of blood flow;
Figure 2(a) is a perspective view of a rdial bioprosthetic heart valve;
Figure 2(b) is a view from an w side of the bioprosthetic heart valve of Figure
2(a) when the valve is in a closed configuration;
Figure 2(c) is a view from an outflow side of the bioprosthetic heart valve of Figure
2(a) when the valve is in an open configuration;
Figure 3(a) is a perspective view of a synthetic polymer leaflet valve having three
relatively stiff ts and ting poor haemodynamic performance;
Figure 3(b) is a view from an outflow side of the synthetic polymer leaflet valve of
Figure 3(a) when the valve is in an open configuration wherein the valve
exhibits inadequate opening;
Figure 3(0) is a perspective view of a synthetic polymer leaflet valve having three
relatively flexible leaflets and exhibiting poor durability;
Figure 3(d) is a view from an outflow side of the tic polymer leaflet valve of
Figure 3(c), when the valve is in an open configuration wherein the
valve exhibits high bending stresses;
Figure 3(a) is a perspective view of the synthetic polymer leaflet valve of Figure 3(0)
showing typical locations of leaflet tears after repeated g in a
fatigue tester;
Figure 4 is a perspective view of a synthetic polymer leaflet valve constituting an
embodiment of the present invention;
Figure 5(a) is a perspective view of a frame of the synthetic polymer leaflet valve of
Figure 4;
Figure 5(b) is a contour map of the leaflets of the synthetic polymer leaflet valve of
Figure 4 viewed from an outflow side;
Figure 6 is a schematic cut-away perspective view of the synthetic polymer leaflet
valve of Figure 4 in use in two different positions within the heart of a
subject;
Figure 7 is a partial contour map of the leaflets of the synthetic polymer t
valve of Figure 4 in different operating configurations viewed from an
outflow side;
Figure 8 is a ctive view of the valve frame of Figure 4 oned on a
former for dip-moulding.
Figure 9 is a longitudinal cross-section through the former shown in Figure 8;
Figure 10(a) is a cross-section of the valve of Figure 4 in a longitudinal plane of the
valve in the vicinity of a base n of a frame of the valve showing a
t surrounding the base portion;
Figure 10(b) is a cross-section of the valve of Figure 4 in a lateral plane of the valve
in the vicinity of a post portion of the frame showing integrally formed
adjacent leaflets surrounding the post portion and passing through a slit
in the post portion;
Figure 11 is a view from an w side of a bi-leaflet valve constituting a further
embodiment of the t invention showing a closed configuration
(solid line) and an open configuration (dashed line) of the valve leaflets;
1O Figure 12(a) is a perspective view of a first ative frame for the synthetic polymer
leaflet valve of Figure 4;
Figure 12(b) is a section of the frame of Figure 12(a) in a longitudinal plane in
the vicinity of a base portion of the frame of Figure 12(a) showing a
leaflet extending through and surrounding the base portion;
Figure 13(a) is a perspective view of a second alternative frame for the tic
polymer leaflet valve of Figure 4;
Figure 13(b) is a cross-section of the frame of Figure 13(a) in a udinal plane in
the vicinity of a base portion of the frame of Figure 13(a) showing a
leaflet extending through and surrounding the base portion;
Figure 14(3) is a perspective view of a synthetic polymer leaflet valve constituting a
yet further embodiment of the present ion;
Figure 14(b) is a l contour map of the leaflets of the synthetic polymer leaflet
valve of Figure 14(a) in different operating configurations viewed from
an outflow side;
Figure 15(a) is a schematic perspective view showing the assembly of a frame of an
artificial heart valve and an attachment ring;
Figure 15(b) is a schematic plan view of the attachment ring of Figure 15(a);
Figure 15(0) is a schematic cross-section through a base portion of the attachment
ring of Figure 15(a); and
Figure 15(d) is a tic cross-section through a base portion of the attachment
ring of Figure 15(a) in the ty of a female engagement feature of the
attachment ring.
DETAILED DESCRIPTION OF THE DRAWINGS
With reference initially to Figure 1(a) through 1(e), a natural aortic valve 2
comprises three pocket—like pouches or leaflets 4 of thin, flexible tissue attached
circumferentially to the base or annulus of the aorta 6. The ts 4 are attached to
an internal wall 8 of the aorta 6 along curved edges 9. Each leaflet 4 has a free edge
that extends in a generally lateral plane with respect to the aorta 6 and is attached
to the aorta wall 8 in regions 11 known as commissures. As shown in Figure 1(b) and
1(0), when the valve 2 is in a closed configuration, the leaflets 4 are in apposition with
one another. As illustrated in Figure 1(b). when the valve 2 is in a closed configuration,
the free edges 10 are generally convex when viewed from the outflow side. The
leaflets 4 move passively in response to pressure differences on either side of the
valve 2 into the open configuration shown in Figures 1(d) and 1(e), allowing one-way
passage of blood from the left ventricle of the heart (not shown) during its contraction
(emptying phase). and closing to prevent reflux of blood into the ventricle during its
relaxation (filling phase).
Figure 2(a) shows a perspective view.of bioprosthetic valve 12, whilst Figures
2(b) and 2(0) show the same bioprosthetic valve 12 in closed and open configurations
respectively. The bioprosthetic valve 12 comprises a sheet of pericardium (the fibrous
sac surrounding the heart) from a donor such as a calf, with rdial ts 14
mounted within (or around) a frame or stent 16 comprising an annular sewing ring base
n 18 and three projections 20 extending therefrom.
Figure 3(a) rates a synthetic ric valve 22 comprising three relatively
stiff synthetic polymeric leaflets 24 attached to a frame 26. The frame 26 comprises an
annular sewing ring base portion 28 defining an inlet aperture 29 (shown in Figure 3(b))
and three projections 30 extending therefrom. The projections 30 lie on a generally
cylindrical e which extends h the base portion 28. Furthermore, the
leaflets 24 are ed to the frame 26 along respective curved lines 32 which lie on
the same generally cylindrical surface as the projections 30. Such a synthetic
polymeric valve 22 may, however, suffer from poor haemodynamic function as
illustrated in Figure 3(b) which shows the tic polymeric valve 22 in an open
configuration in which the valve still presents an unacceptably high restriction to blood
flow. If the polymer from which the leaflets 24 are formed is stiff, not readily distensible
(high modulus), or is used to make a thick leaflet, or has some form of internal
rcement (such as a preformed fibre network, or embedded carbon nanotubes),
the leaflets 24 do not move readily in response to pressure differences across them.
This results in clinically unacceptable obstruction to d blood flow, and sluggish
closure causing excessive reflux (“poor haemodynamic function"). Thus, an outlet
orifice 33 formed by free edges 34 of the open leaflets 24 cannot reach the same
ions as the inlet re 29. This is, in part, a consequence of the fact that a
distance between adjacent commissures 35 measured around the inlet aperture 29 of
the frame 26, (rad/3 where d is the diameter of the inlet aperture 29), is greater than a
length of a free edge 34 of one leaflet (d), and, in part, because the commissural
regions of the free edges 34 adjacent to the commissures 35 cannot open to a
theoretical fully open position because of the inherent stiffness of the ts 24. The
restriction of outlet orifice area increases with increasing leaflet stiffness. Such a stiff
polymer valve 22 that opens inadequately gives poor haemodynamic function and may
also create areas of sh blood flow beneath the poorly opening leaflets 24 in the
commissural regions, predisposing to local blood clotting.
Figure 3(c) illustrates a synthetic polymeric valve 42 comprising three relatively
flexible synthetic polymeric leaflets 44 attached to a frame 46. The frame 46 comprises
an r sewing ring base portion 48 defining an inlet aperture 49 (shown in Figure
3(d)) and three projections 50 ing therefrom. The projections 50 lie on a
generally cylindrical surface extending through the base portion 48. The leaflets 44 are
ed to the frame 46 along tive curved lines 52 which lie on the same
generally cylindrical surface as the projections 50. Such a tic polymeric valve 42
may provide reduced restriction when in the open configuration shown in Figure 3(d) at
3O the expense of reduced durability compared with the synthetic polymeric valve 22 of
Figure 3(a). If the polymer from which the leaflets 44 are made is y distensible
(low modulus), or if the leaflets 44 are very thin, the leaflets 44 will move readily in
response to pressure differences across them (“good haemodynamic function”).
Although such leaflets 44 offer little obstruction to forward blood flow and close readily
to minimise reflux through the valve 42, durability may be limited. The valve 42 is
unable to withstand the constant opening and closing stresses on the leaflets 44, and
these ally tear as illustrated in Figure 3(e).
Features of the design of the valve 42 of Figures 3(0) to 3(e) may also
contribute to poor lity. Full g of the leaflets 44 requires acute bending
(small radius of curvature) of the leaflets 44 in the region of commissures 55, with the
result that local stresses, particularly on the commissural regions of the leaflets 44,
may be very high, and may lead to the formation of tears 58 in the commissural regions
of the leaflets 44 as shown in Figure 3(e). Furthermore, during opening of the polymer
leaflets 44, because the length of respective free edges 60 in their closed configuration
is longer than the distance between projections 50 of the frame 46, the free edges 60
may buckle, or bend acutely and arbitrarily, as the free edges 60 pass between the
projections 50, and this buckle is propagated down into the middle of each t 44,
causing high local bending stresses that may ultimately lead to the ion of tears
62 in the middle of the leaflets 44.
Figure 4 shows a first embodiment of a synthetic polymeric heart valve
generally designated 102 which is intended to overcome or alleviate some of the
foregoing problems with known synthetic polymeric heart valves. The synthetic
polymeric heart valve 102 comprises three relatively flexible polyurethane leaflets 104
attached to a relatively rigid stainless steel frame 106. The ts 104 are flexible
relative to the frame 106 but are generally formed from a stiffer, more durable,
polyurethane material than that used for polymeric leaflets of known synthetic
polymeric heart valves 22, 42.
As shown in Figure 5(a), the frame 106 comprises a generally annular base
portion 108 ng an aperture 109 and three post portions 110 extending from the
base portion 108 in a lly longitudinal direction. Each leaflet 104 is attached to
the base portion 108 of the frame 106 along a corresponding base line of attachment
112. Each leaflet 104 is attached between two adjacent post portions 110 of the frame
106 along respective lines of attachment 114. The lines of attachment 114 are
generally straight and extend in a udinal direction perpendicular to the base.
Each leaflet 104 has a free edge 115 which s n two adjacent post
portions 110 of the frame 106 opposite the base line of attachment 112. The free edge
115 of each leaflet is free to move relative to the frame 106 in response to pressure
differences on either side of the leaflets 104.
Figure 5(b) shows a contour map of the leaflets 104 in their l or as-
formed configuration in which r numbers 1 — 11 represent constant height
contours increasing in distance from the base portion 108 of the frame 106 such that
contour number 1 represents the base line of attachment 112 of a leaflet 104 and
contour number 11 represents a lower boundary 116 of a vertical co-aptation region
117 which extends from the free edge 115 of the t to the lower boundary 116 of
the co-aptation region 117. From Figure 5(b), ore, it is apparent that a lateral
section taken through each leaflet comprises a junction in the form of a point of
inflection 118, an outwardly convex portion 119 extending from a first post portion 110
to the point of inflection 118 and an outwardly concave portion 120 extending from a
second post portion 110 to the point of inflection 118 so that each section has an “S-
'10 shape” when viewed from the outflow direction. Accordingly, each lateral cross-section
through each leaflet 104 is longer than the base line of attachment 112 of the leaflet
104. Furthermore, the free edge 115 of each t 104 is longer than the
corresponding base line of attachment 112. Each leaflet 104 adopts a curved shape in
three dimensions which comprises an outer surface having a three-dimensional
generally convex portion 121 to one side of each point of inflection 118 and a three-
dimensional generally concave portion 122 to the other side of each point of inflection
118. in addition. since the lines of attachment 114 of each leaflet 104 are ht in
the vicinity of each post n 110 of the frame 106. the contour numbers 1 — 11
shown in Figure 5(b) meet in the vicinity of each post portion 110 of the frame 106.
The point of inflection 118 of each lateral cross-section of a leaflet 104 between the
base line of attachment 112 and the lower boundary 116 of the ation region 117
lies along a straight line 124 which extends from a point of ection 126 of a line of
attachment 114 adjacent to the concave n 122 of the leaflet 104 with the base
line of ment 112 to the point of inflection 118 at the mid-point of the lower
boundary 116 of the co-aptation region 117.
As will be described in more detail below, a mould or former is used to define
the shape of each leaflet 104 during the manufacturing thereof. Figure 9 shows a
longitudinal cross—section through such a former showing the profile of a surface of the
former to which a leaflet 104 conforms during the manufacturing thereof. Accordingly,
each contour having a number 1 to 11 of the leaflets 104 is d by a corresponding
contour having a number 1 to 11 as indicated on the surface of the former in Figure 9.
in use, the base portion 108 of the frame 106 is fitted into a circumferential
sewing ring (not shown) h which surgical anchoring sutures pass to secure the
artificial heart valve 102 into the attachment area us) of the natural heart valve
that requires replacement. As shown in Figure 6 (in which “LA" indicates the left
atrium, "LV" indicates the left ventricle, and “A0" indicates the aorta), the cial valve
102 is orientated in such a way as to allow appropriate one-way flow of blood through a
heart 130, thus enabling it to be used to replace the aortic valve (ventriculo-arterial
valve) and/or a mitral valve (atrio-ventricular .
When the valve 102 is configured in the closed configuration d “C” as
shown dashed in Figure 7, the free edges 115 of the flexible ts 104 and the inner
surfaces of the co-aptation regions 117 of the leaflets 104 engage one another so as to
reduce or prevent blood flow through the valve 102. When the pressure d on the
flexible leaflets 104 from the inflow side sufficiently exceeds that exerted from the
1O outflow side (as occurs at the commencement of ejection of blood) the leaflets 104
move outward such that the free edges 115 adopt an open configuration denoted “O” in
Figure 7 to create an outflow orifice 132, the maximum size of which can be varied by
the design of the S-shape that determines the length of the leaflet free edge 115. In
Figure 7, the contour numbers 3, 5, 7 and 9 represent constant height contours of a
leaflet 104 in the open configuration “”.0 As will be described in more detail below, the
free edges 115 of the ts 104 are formed with a configuration denoted “F” which is
intermediate the closed configuration d “C” and the open configuration denoted
The design of the valve 102 permits use of stiffer more durable. biocompatible
materials for the leaflets 104 so as to provide a reduced restriction to blood flow in the
open configuration "0” compared with conventional synthetic polymer heart valves
made from such stiffer materials whilst also ng susceptibility to tearing of the
leaflets 104. This improved immunity to damage is attributable not only to the
increased stiffness of the leaflets 104, but also to the point of inflection defined along a
lateral section through each leaflet 104. More specifically, the stiffness and the
arrangement of each t 104 means that, although the curvature of each leaflet 104
at a point of inflection 118 and/or the curvature of each leaflet 104 on either side of a
point of tion 118 may change in response to changes in re differential
across the ts 104, the three—dimensional generally convex and concave portions
121, 122 of the leaflets 104 generally persist for different pressure differentials across
the leaflets 104. As a consequence of such movement, stresses in the leaflets 104 are
distributed across the widths of the leaflets 104 and the commissural regions of the
leaflets 104 in the vicinity of the frame 106 do not have to bend as much as the
commissural regions of leaflets of conventional tic heart valves (such as the
leaflets 44 shown in Figures 3(c) to 3(e)) for a given outflow orifice size.
The stiffness and the arrangement of each leaflet 104 also means that each
leaflet 104 has a predetermined shape for a given pressure differential across the
leaflet 104. The predetermined shape of each leaflet 104 for a given pressure
differential across the leaflet 104 is selected so as to prevent arbitrary buckling or
wrinkling of each leaflet 104, thus avoiding excessive bending es in each t
104. in particular, each leaflet 104 is formed so as to have a ermined shape
throughout movement n open and closed urations.
With reference to Figure 7. as each leaflet 104 moves from its closed
configuration “C" towards its corresponding open configuration "0" between two
adjacent post portions 110, the three~dlmensiona| lly convex and concave
portions 121, 122 of the leaflet 104 swing or pivot about their respective lines of
attachment 114. The curvature of the convex and concave portions 119, 120 of the
free edge 115 of the leaflet 104 are accentuated until the point of inflection 118 along
the free edge 115 crosses a straight line extending between the adjacent post portions
110. Once the point of inflection 118 along the free edge 115 crosses the ht line
extending between the adjacent post portions 110, the curvature of the convex portion
119 of the free edge reduces whilst the ure of the concave portion 120 of the free
edge increases and the three-dimensional generally convex portion 121 of the leaflet
104 appears to grow at the expense of the three-dimensional generally concave portion
122 of the leaflet 104 until each leaflet 104 moves reaches its corresponding open
configuration "”.0 Corresponding changes are observed for each lateral cross-section
of the leaflets 104 as defined by contours 1 — 11. The changes in curvature are also
accompanied by movement of the points of inflection 118 along the lateral cross-
sections of the leaflets 104 to odate the changes in curvature of the convex
and concave portions 121, 122 of the leaflets 104. This s in each leaflet 104
moving continuously in a predictable manner such that the convex portion 121 of the
outer surface of each leaflet 104 appears to grow at the expense of the concave
portion 122 of the outer surface of the leaflet 104 when viewed from the w side of
the valve 102. As a uence of such movement, buckling or wrinkling of each
leaflet 104 and the associated bending stresses may be avoided. This permits the
valve 102 to be ured such that the bending stresses induced in each leaflet 104
as a consequence of such movement of each leaflet 104 do not exceed a threshold
g stress so that damage such as tearing of each leaflet 104 is thereby avoided.
The leaflets 104 of the three-leaflet heart valve 102 are configured to define a
lateral section which imparts a spiral blood flow in a counter-clockwise direction
when viewed from the outflow side of the valve 102. A lateral cross-section taken
through each leaflet 104 defines an outwardly convex portion 119 followed by an
dly concave portion 120 in a generally counter-clockwise direction about an axis
defined by the aperture 109 when viewed from the outflow side of the valve 102. In
use, when implanted into a heart of a human or animal subject, such a spiral blood flow
may improve the ency of operation of the heart ed with the efficiency of the
heart when using known artificial heart valves.
The design of the synthetic heart valve 102 represents a significant departure
from the design of a natural heart valve which has evolved naturally over millions of
years and which works well for a life-time, but relies for this on the physical and
biological characteristics of the complex leaflet structure, composed of collagen, elastin
and rotein matrix, as well as the living nature of the tissue that is able to repair
and replace itself. Furthermore, the principles of design for the synthetic heart valve
102 are ry to the principles of design employed for conventional man-made heart
valve designs which dictate that such conventional man-made heart valve designs
should mimic natural heart valve designs. In particular, the design of synthetic heart
valve 102 differs appreciably from conventional man-made heart valve designs that
mimic natural heart valve designs at least in the straight lines of attachment 114 along
which each leaflet 104 is connected to post portions 110 of the frame 106.
Furthermore, each lateral cross-section through each leaflet 104 defines outwardly
convex and concave ns 119, 120 and a point of inflection 118 between the
convex and concave ns 119, 120. A further distinguishing e of the synthetic
heart valve 102 is that each lateral cross-section through each leaflet 104 and the free
edge of each leaflet 104 are both longer than the base line of attachment 112 of each
leaflet 104. .
Figure 8 illustrates the manufacture of the heart valve 102 using a dip-moulding
process in which the frame 106 is positioned appropriately on a former 140, dipped in a
solution of polyurethane and allowed to dry in an oven. The configuration of the former
140 es the configuration of the valve ts 104 on ion. The configuration
of the free edges 115 of the leaflets 104 on formation is denoted “F" in Figure 7. in the
absence of any pressure differential across the leaflets 104, the leaflets 104 tend to
return to the uration of the valve leaflets 104 on ion and, in particular, the
free edges 115 of the leaflets 104 tend to return to the configuration denoted “".F This
is a consequence of the properties of the material from which the leaflets are formed
and is, in particular, a result of stresses induced in the al of the leaflets 104 as
the ts 104 move away from their ion or default configuration. Moreover, the
default configuration of the leaflets 104 is deliberately designed such that the free
edges 115 of the leaflets 104 are not so far apart that they cannot move from their
default configuration “F” to their closed configuration "C” so as to prevent blood flow in
a backward direction through the valve 102 in response to an appropriate pressure
ential. Furthermore, the default configuration is deliberately designed such that
the free edges 115 of the leaflets 104 may readily move from their default configuration
“F" to their open configuration “0" so as to minimise restriction to blood flow in a
fonrvard ion through the valve 102 in response to an appropriate pressure
differential.
Figure 9 shows the former 140 prior to mounting of the frame 106 on the former
140. The former 140 is formed from stainless steel and comprises a threaded
attachment portion 142 for attachment to a support member (not shown) and a body
portion 144 having a highly polished surface 146 to promote release of the artificial
heart valve 102 from the former 140 after the polyurethane solution has dried. A
centrally located through-hole 148 extends longitudinally through the former 140. The
through-hole 148 is configured to receive an occluding pin 150 having a shank portion
152 and head portion 154. The shank portion 152 of occluding pin 150 serves to
occlude the through-hole 148 so as to prevent ingress of polyurethane solution during
dip-moulding into the through-hole 148. The head portion 154 of the occluding pin 150
serves to keep a region around an opening 155 of the through-hole 148 formed in the
ment portion 142 of the former 140 y free of the polyurethane solution. The
former 140 comprises a location hole 156 configured for alignment and attachment of
the frame 106 to the former 140 using a locating pin (not shown) to prevent relative
movement therebetween during the dip—moulding process. This ensures that each side
edge 158 of the former is aligned adjacent to a corresponding post portion 110 of the
frame 106.
After dip-moulding. the occluding and locating pins 154, 156 are d from
the former 140. Subsequently, the release of the artificial heart valve 102 from the
former 140 may be aided by ing a release fluid such as water or saline into the
opening 155 of the through-hole so as to induce planar separation of the leaflets 104
from the highly polished e 146 of the body n 144 of the former 140. It
should be understood that the former is dipped in the ethane solution such that
the ethane solution solidifies to a level above the lower ries 116 of the co-
aptation regions 117 defined by contour 11 on the former 140. The leaflets 104 may be
subsequently trimmed at a level above contour 11 so as to form the free edges 115
and define a height of the co-aptation regions 117 from the lower boundaries 116 of the
co-aptation regions 117 to the free edges 115.
The dip-moulding process allows the polymer to surround the frame 106
including the base portion 108 as shown in Figure 10(a) and to pass through slits 160
in the post portions 110 of the frame 106 as shown in Figure 10(b) so as to completely
envelope the frame 106 and ensure integral formation of the leaflets 104 and secure
attachment of the leaflets 104 to the frame 106. Such a manufacturing process may
ensure the integral formation and secure attachment of the leaflets 104 to the frame
106 by ng the frame 106 with a uous sheet of the polyurethane. This has
the age that t attachment is not limited to adhesion of the ethane to
one or more portions of the frame 106 thus reducing the risk of the leaflets 104
becoming detached from the frame 106. Furthermore, the slits 160 are angled so as to
ensure that the leaflets 104 enter and/or exit the slits 160 with a predetermined
configuration. Such an angle may, in particular. ensure that the curvature of a lateral
cross-section of the leaflets 104 in the vicinity of the post portions 110 is continuous
with a curvature of the convex and concave portions 119, 120 of the lateral cross-
section of the leaflets 104.
Figure 11 shows a second embodiment of a synthetic polymeric heart valve
generally designated 202 comprising two flexible leaflets 204 ed to a frame 206
along two generally straight lines of attachment defined by respective post portions 210
extending from a base portion 208 which defines an re for blood flow. Each
leaflet 204 is attached to the base portion 208 of the frame 206 along a base line of
attachment 212. Each leaflet 204 extends along a direction of blood flow to a free edge
215 which is movable from a closed configuration d "C” in Figure 11 to an open
configuration denoted “O" and shown dashed in Figure 11. The leaflets 204 of the bi—
Ieaflet heart valve 202 are configured to define a lateral cross-section which imparts a
spiral blood flow in a clockwise ion when viewed from the outflow side of the valve
202. A lateral cross-section through each leaflet 204 defines an outwardly concave
portion followed by an outwardly convex n in a generally counter-clockwise
ion about an axis defined by the base portion 208 when viewed from the outflow
side of the valve. In other respects, the flet heart valve 202 is designed using the
same design principles outlined above for the three-leaflet synthetic polymeric heart
valve 102 and operates in a like manner.
One skilled in the art will understand that various modifications may be made to
the forgoing embodiments without departing from the scope of the t invention.
For example, Figure 12(a) shows a perspective View of a first alternative frame 306 for
the synthetic polymer leaflet valve of Figure 4 comprising a base portion 308 and a
ity of through—holes 370 extending through the base portion 308. Figure 12(b) is
a cross-section of the frame of Figure 12(a) in a longitudinal plane in the vicinity of the
base portion 308 which shows a leaflet 304 extending through a through-hole 170 and
surrounding the base portion 308. Each of the through-holes 370 are angled upwardly
by approximately 30° to. the ntal so as to ensure that a curvature of the leaflet
304 adjacent to the base portion 308 is continuous with a curvature of convex and
concave portions 321, 322 of the leaflets 304.
Figure 13(a) shows a perspective view of a second alternative frame 406 for the
synthetic polymer leaflet valve of Figure 4 comprising a base portion 408 and a plurality
of slits 480, each slit 480 extending through the base portion 408. Figure 13(b) is a
cross-section of the frame of Figure 13(a) in a udinal plane in the vicinity of the
base portion 408 which shows a leaflet 404 extending through a slit 480 and
surrounding the base portion 408. Each of the slits 480 are angled upwardly by
approximately 30° to the horizontal so as to ensure that a curvature of the leaflet 404
nt to the base portion 408 is Continuous with a ure of convex and concave
portions 421, 422 of the leaflets 404.
in further alternative frames (not shown) for the synthetic polymer leaflet valve
of Figure 4, d of having slits for the attachment of the leaflets to the post portions
of the frame along the generally straight lines of attachment, the post portions may
each define a plurality of h holes aligned along the post portions for the
attachment of leaflets along generally straight lines of attachment.
Rather than being rigid or semi-rigid, the frame 106 may be flexible. For
example, the frame 106 may be expandable to permit the valve 102, 202 to enlarge
with l growth in a growing subject such as a child, or to be forcibly ed by a
balloon or other method, t making the valve leaflets 104, 204 incompetent and
leaking. Apposition of the leaflets 104, 204 at the co-aptation regions 117, 217 is
maintained by alteration of the curvature of the ts as the post portions 110, 210
move apart with enlargement of the valve 102, 202.
It should be understood that, in some embodiments, one or more leaflets may
be ured to define a lateral cross-section which imparts a spiral blood flow in a
counter-clockwise direction when viewed from an Outflow side of the valve. A lateral
cross-section through each leaflet may define an outwardly convex n followed by
an outwardly concave portion in a generally counter-clockwise direction about an axis
d by the aperture when viewed from the outflow side of the valve. For example,
the three leaflet heart valve 102 shown in Figures 4, 5(b), 7 and 8 is ured such
that the leaflets 104 define a lateral cross-section which imparts a spiral blood flow in a
r-clockwise ion when viewed from the outflow side of the valve 102.
In other embodiments, one or more leaflets may be configured to define a
lateral cross-section which imparts a spiral blood flow in a clockwise direction when
viewed from the outflow side of the valve. A lateral cross-section through each leaflet
may define an dly concave portion followed by an outwardly convex portion in a
generally counter-clockwise direction about the axis defined by the aperture when
viewed from the outflow side of the valve. For example, the two leaflet heart valve 202
of Figure 11 is configured such that the leaflets 204 define a lateral cross-section which
imparts a spiral blood flow in a clockwise direction when viewed from the outflow side
of the valve 202. Similarly, Figures 14(a) and 14(b) show a three leaflet heart valve
302 which is configured such that the leaflets 304 define a lateral cross-section which
imparts a spiral blood flow in a clockwise direction when viewed from the outflow side
of the valve 302.
Referring to Figure 15(a) there is shown a schematic perspective view
rating the assembly of a frame 406 of an cial heart valve and an attachment
ring generally designated 500. Referring to s 15(a) and 15(b), the attachment
ring 500 ses an r base portion 502 which defines three female ng
features in the form of three receptacles 504 which are distributed circumferentially
around the base portion 502. As shown most clearly in the cross-sectional view
through the base portion 502 of Figure 15(0), the base portion 502 comprises an
annular support structure 506 surrounded by a resiliently deformable cover material in
the form of a Dacron layer 508. In use, a running suture 510 is used to sew the base
portion 502 to a passageway (not shown) within the heart of a human or animal subject
by looping a continuous length of suture repeatedly around the base n 502. The
Dacron layer 508 is then compressed against an inner surface of the passageway (not
shown) to provide a seal therewith around an outer surface of the base portion 502.
The suture 510 sinks into the Dacron layer 508 so as to avoid interfering with the seal
between the outer surface of the base portion 502 and the inner surface of the
passageway (not shown) and so as to avoid interfering with a subsequent seal formed
between an inner surface of the base portion 502 and an outer surface of an annular
base portion 408 of the frame 406. Such a sewing method may permit the use of an
attachment ring 500 having an annular base portion 502 which has a radial extent
which is ntially less than the radial extent of known sewing rings. This may
permit the use of artificial heart valves which define greater blood flow apertures.
As shown in Figure 15(d) each receptacle 504 comprises a recess 512 and a
resiliently deformable member 514 which extends downwardly and across the recess
512. The recess 512 has a generally rectangular cross-section. The frame 406 of the
artificial heart valve comprises three rigid male engaging features in the form of three
bayonets 516 each having corresponding leg and foot portions 518, 520. Each
bayonet 516 has a generally rectangular cross-section which is configured to be
received within a corresponding recess 512. During ly, each bayonet 516 is
aligned with and pushed into a corresponding recess 512 so that the foot portion 520 of
the bayonet first engages and then deforms a corresponding deformable member 514
When the foot n 520 is pushed fully into the recess 512, the foot portion 520
engages a closed end 522 of the recess 512 thus permitting a lower end 524 of the
able member 514 to spring back to its natural position and thereby lock the
corresponding bayonet 516 in ment within the recess 512. Such a push fit
arrangement may simplify the attachment of the frame 406 of an artificial heart valve to
a passageway (not shown) within the heart of a human or animal subject.
Claims (69)
1. An artificial heart valve comprising a support structure defining an aperture for blood flow and a flexible leaflet which is e relative to the support structure 5 n an open configuration in which the leaflet permits blood flow through the aperture and a closed configuration in which the leaflet restricts blood flow through the aperture, n the aperture defines an axis, and a lateral cross-section taken through the leaflet in a plane lateral to the axis defines an outwardly convex portion, an 10 outwardly concave portion and a junction between the convex and concave ns when the t is in the open and closed configurations and all leaflet configurations intermediate the open and closed configurations including a natural or t configuration in which the t is formed, and wherein the leaflet is attached to the support structure along first and second at 15 least partially straight lines of attachment such that movement of the leaflet between the open and closed configurations results in the convex portion of the l cross- section pivoting about one of the first and second lines of attachment and the concave portion of the lateral cross-section pivoting about the other of the first and second lines of attachment.
2. An artificial heart valve according to claim 1, n the first and second lines of attachment are generally parallel.
3. An artificial heart valve according to claim 1 or 2, wherein the first and second 25 lines of attachment extend in a direction which is generally parallel to the axis.
4. An artificial heart valve according to any one of claims 1 to 3, wherein the convex n extends from one of the first and second lines of attachment to the junction and the concave portion extends from the other of the first and second lines of 30 attachment to the junction.
5. An artificial heart valve according to any preceding claim, wherein the lateral cross-section has a curvature which is discontinuous at the junction. 35
6. An artificial heart valve according to any one of claims 1 to 4, wherein the lateral cross-section has a curvature which is continuous at the junction.
7. An cial heart valve according to any one of the preceding , wherein the junction comprises a region of inflection.
8. An artificial heart valve according to any one of the preceding claims, wherein the junction comprises a point of inflection.
9. An artificial heart valve according to any one of the preceding claims, wherein the junction comprises a curved .
10. An artificial heart valve ing to any one of the preceding claims, wherein the junction comprises a straight region.
11. An artificial heart valve according to any one of the preceding claims, wherein 15 the heart valve is configured such that movement of the leaflet results in a change in curvature of the convex and concave portions of the lateral cross-section.
12. An artificial heart valve according to any one of the preceding claims, wherein the heart valve is configured such that movement of the t away from the closed 20 configuration towards the open configuration results in a reduction in curvature of the convex portion of the lateral cross-section and an increase in curvature of the concave portion of the lateral cross-section.
13. An artificial heart valve according to any one of the ing , wherein 25 the heart valve is configured such that movement of the leaflet from the closed configuration to the open configuration results in an initial increase in curvature of the convex and concave portions of the lateral cross-section of the leaflet followed by a decrease in curvature of the convex portion and a further increase in ure of the concave portion.
14. An artificial heart valve according to any one of the preceding claims, wherein the heart valve is configured such that movement of the leaflet results in movement of the junction along the l cross-section of the leaflet. 35
15. An artificial heart valve ing to any one of the preceding , n the heart valve is configured such that movement of the leaflet away from the closed configuration towards the open configuration results in movement of the junction along the lateral cross-section of the leaflet away from the first or second line of attachment about which the convex n pivots towards the other of the first and second lines of attachment.
16. An cial heart valve according to any one of the preceding claims. wherein the heart valve is configured such that nt of the leaflet from the closed configuration to the open configuration results initially in no movement of the junction along the lateral cross-section of the leaflet ed by movement of the junction along 10 the lateral cross-section of the leaflet from the first or second line of attachment about which the convex portion pivots towards the other of the first and second lines of attachment.
17. An artificial heart valve according to any one of the preceding claims, wherein a 15 length of the convex portion of the lateral cross-section comprises a greater proportion of a total length of the lateral cross-section in the open configuration than in the closed configuration.
18. An artificial heart valve ing to any one of the ing claims, wherein 20 the leaflet is connected to the support ure along a base line of attachment.
19. An artificial heart valve according to claim 18, n the base line of attachment is adjacent to the aperture. 25
20. An artificial heart valve according to claim 18 or claim 19, wherein the base line of attachment extends circumferentially at least partially around the aperture.
21. An artificial heart valve according to any one of claims 18 to 20, wherein the base line of attachment is dly convex.
22. An artificial heart valve according to any one of claims 18 to 21, wherein the leaflet comprises a free edge which extends opposite the base line of attachment between the first and second lines of attachment, the free edge being movable relative to the support structure, and the free edge defining an outwardly convex portion, an 35 outwardly concave portion and a on between the convex and concave portions.
23. An artificial heart valve ing to claim 22, wherein the junction of the free edge is d substantially half-way along the free edge between the first and second lines of ment.
24. An artificial heart valve according to claim 22 or claim 23, wherein the free edge of the leaflet is longer than the base line of attachment.
25. An artificial heart valve according to any one of claims 22 to 24. wherein each of a plurality of lateral cross-sections taken through the leaflet between the base line of 10 attachment and the free edge defines an outwardly convex n, an dly concave portion and a junction between the convex and concave portions.
26. An artificial heart valve ing to any one of claims 22 to 25, wherein the leaflet defines a co-aptation region which extends from the free edge and which has a 15 plurality of generally identical lateral cross-sections.
27. An artificial heart valve according to claim 26, wherein the co-aptation region extends from the free edge to a boundary which is located between the free edge and the base line of attachment.
28. An artificial heart valve according to claim 27, wherein the leaflet defines first and second lateral cross-sections between the base line of attachment and the boundary of the co-aptation , the first lateral cross-section being closer to the base line of attachment than the second lateral section, and wherein a convex 25 portion of the first lateral cross—section is longer than a convex n of the second lateral cross-section, and a concave portion of the first lateral cross-section is shorter than a concave portion of the second lateral section.
29. An artificial heart valve according to claim 27 or claim 28, wherein the junction 30 of each of the lateral cross-sections taken through the t between the base line of attachment and the boundary of the co—aptation region lie along a pre-determined junction reference line when the leaflet is in an as-formed configuration.
30. An artificial heart valve according to claim 29, wherein the junction reference 35 line is at least partially straight.
31. An cial heart valve ing to claim 29 or claim 30, wherein the junction reference line extends from a point substantially ay along the boundary of the co- on region to a point of intersection between the base line of attachment and the first or second line of attachment about which the concave portion pivots.
32. An artificial heart valve according to any one of the preceding claims, wherein the support structure comprises a base portion defining the aperture and first and second post portions arranged around the aperture and extending from the base portion in a direction which is generally parallel to the axis defined by the re, and 10 the leaflet is connected to the first post portion along the first line of attachment, to the second post portion along the second line of ment and to the base portion along a base line of attachment .
33. An artificial heart valve according to claim 32, wherein the leaflet extends 15 through and nds the first post portion along the first line of attachment and the leaflet extends through and surrounds the second post portion along the second line of attachment.
34. An artificial heart valve according to claim 32 or claim 33, wherein the first and 20 second post portions define respective holes which extend therethrough, the leaflet extends through the hole of the first post portion and the leaflet extends through the hole of the second post portion.
35. An artificial heart valve ing to claim 34, n the respective holes 25 which extend through the first and second post ns are angled with respect to a radial direction relative to the axis defined by the aperture.
36. An artificial heart valve according to claim 34 or claim 35, wherein the respective holes which extend through the first and second post portions each 30 comprise a slit.
37. An artificial heart valve according to any one of claims 32 to 36, wherein the first and second post portions each define a plurality of holes extending therethrough and the leaflet extends through each of the plurality of holes extending through the first and 35 second post portions.
38. An cial heart valve according to any one of claims 32 to 37, wherein the leaflet s through and surrounds the base portion.
39. An artificial heart valve ing to any one of claims 32 to 38, wherein the base portion defines a hole which extends therethrough and the leaflet extends through the hole.
40. An artificial heart valve according to claim 39, wherein the hole which extends through the base portion is angled with t to a radial direction relative to the axis 10 defined by the aperture.
41. An cial heart valve ing to claim 39 or claim 40, wherein the hole which extends through the base portion comprises a slit. 15
42. An cial heart valve according to any one of claims 32 to 41, wherein the base portion defines a plurality of holes which extend therethrough and the leaflet extends through each of the plurality of holes.
43. An artificial heart valve according to any one of the preceding claims, wherein 20 the leaflet is integrally formed on the support structure.
44. An artificial heart valve according to any one of the preceding claims, wherein at least a portion of the support structure is flexible or collapsible. 25
45. An artificial heart valve according to any one of the preceding claims, wherein the support structure comprises a metal, stainless steel, titanium, a r and/or polyether ether ketone (PEEK).
46. An artificial heart valve according to any one of the preceding claims, comprising 30 first and second inter-engageable parts, wherein the first part is configured for connection to a heart and the leaflet is connected to the second part along the first and second lines of ment.
47. An artificial heart valve according to any one of the preceding claims, wherein 35 the valve is configured for percutaneous delivery.
48. An artificial heart valve according to any one of the preceding claims, wherein the support structure comprises a frame.
49. An artificial heart valve according to any one of the preceding claims, wherein the support structure comprises a stent.
50. An artificial heart valve according to any one of the preceding , wherein the t structure comprises a n of a heart. 1O
51. An artificial heart valve according to any one of the preceding claims, wherein the leaflet comprises a synthetic material.
52. An artificial heart valve ing to any one of the preceding claims, wherein the leaflet comprises a polymeric material.
53. An artificial heart valve ing to any one of the preceding claims, wherein the leaflet comprises polyurethane.
54. An artificial heart valve according to any one of the preceding , wherein 20 the leaflet is ured to define a lateral cross-section which imparts a spiral blood flow in a counter-clockwise direction when viewed from an outflow side of the valve.
55. An artificial heart valve according to any one of the preceding claims, wherein the lateral section through the leaflet defines the outwardly convex portion 25 followed by the outwardly concave portion in a generally r-clockwise direction about the axis defined by the aperture when viewed from the outflow side of the valve.
56. An artificial heart valve according to any one of claims 1 to 53, wherein the leaflet is configured to define a lateral cross-section which imparts a spiral blood flow in 30 a clockwise direction when viewed from the outflow side of the valve.
57. An artificial heart valve according to claim 56, wherein the lateral cross-section through the t defines the outwardly concave portion followed by the outwardly convex portion in a generally counter—clockwise direction about the axis defined by the 35 aperture when viewed from the outflow side of the valve.
58. An artificial heart valve according to any one of the ing claims, comprising one or more further flexible leaflets, wherein each of the one or more further leaflets is movable relative to the support structure between an open configuration in which the leaflet and the one or more further leaflets permit blood flow through the aperture and a closed configuration in which the leaflet and the one or more further leaflets restrict blood flow through the aperture, wherein a lateral cross-section taken through any one of the one or more further leaflets in a plane lateral to the axis defines a ponding outwardly convex portion, a ponding outwardly concave portion and a corresponding junction between the 10 convex and concave portions when the further leaflet is in the open and closed configurations and all leaflet configurations intermediate the open and closed configurations including a natural or default configuration in which the further leaflet is formed, and wherein each of the one or more further leaflets is attached to the support 15 structure along respective at least lly straight first and second lines of attachment such that movement of any one of the one or more further leaflets between a corresponding open and closed configuration results in the convex n of the lateral cross-section of the further leaflet pivoting about one of the corresponding first and second lines of attachment and the concave n of the l cross-section of the 20 further leaflet pivoting about the other of the corresponding first and second lines of attachment.
59. An artificial heart valve according to claim 58, wherein the curvature of a convex portion of the lateral cross-section of the leaflet is ntially matched to the 25 ure of a e n of a l cross-section of one of the one or more further leaflets adjacent to the leaflet, wherein said lateral cross-sections are taken through the leaflet and the adjacent further leaflet in the same plane lateral to the axis.
60. A leaflet for an artificial heart valve according to any preceding claim, the leaflet 30 comprising first and second ends which are configured for attachment to the support structure along the first and second lines of attachment tively.
61. A former for use in manufacturing an artificial heart valve, comprising an outer surface which is configured to define a flexible leaflet of a heart valve ing to any 35 one of claims 1 to 60 on solidification of a liquid thereon.
62. A former according to claim 61, wherein the outer surface is configured to ss adhesion of the liquid to the outer surface.
63. A former according to claim 61 or claim 62, wherein the former defines a h—hole extending therethrough which is configured to receive an occluding member so as to prevent ingress of a liquid into the through-hole when an entrance to the hole is dipped in the liquid.
64. A method of manufacturing an artificial heart valve sing: 10 attaching a flexible leaflet to a support ure along first and second at least partially straight lines of attachment, such that the leaflet is movable relative to the support structure between an open configuration in which the leaflet permits blood flow through an aperture d by the t structure and a closed configuration in which the leaflet restricts blood flow through the aperture, wherein the aperture defines 15 an axis, and a lateral cross-section taken through the leaflet in a plane lateral to the axis defines an outwardly convex portion, an outwardly concave portion and a on between the convex and concave portions when the leaflet is in the open and closed configurations and all leaflet configurations intermediate the open and closed configurations including a natural or default configuration in which the leaflet is formed, 20 and such that movement of the leaflet between the open and closed configurations results in the convex portion of the lateral section pivoting about one of the first and second lines of attachment and the concave portion of the lateral section pivoting about the other of the first and second lines of attachment. 25
65. A method according to claim 64 comprising: dip-coating a support structure in a liquid; and permitting or causing the liquid to solidify so as to define the flexible leaflet.
66. A method of cturing an artificial heart valve according to claim 65 3O comprising: mounting the support structure on a former prior to dip—coating the support ure in the liquid; and removing the support structure and the flexible leaflet from the former after solidification of the liquid.
67. A method of cturing an artificial heart valve according to claim 66, comprising dipping the former with the support structure mounted thereon in the liquid so as to coat an outer surface of the former.
68. A method of manufacturing an artificial heart valve according to claim 67, comprising trimming the leaflet above a lower edge of a co-aptation region of the leaflet formed after solidification of the liquid so as to define a free edge of the leaflet.
69. A method of manufacturing an artificial heart valve according to any one of 10 claims 64 to 68, wherein the former defines a through-hole extending therethrough which is configured to receive an occluding member, and the method comprises: occluding the through-hole with the occluding member prior to dipping the former in the liquid so as to prevent ingress of the liquid into the h-hole; removing the occluding member from the through-hole after solidification of the 15 liquid; and injecting a e fluid to aid separation of the fied liquid from the outer surface of the former,
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB1102828.9 | 2011-02-18 | ||
GB1102828.9A GB2488530A (en) | 2011-02-18 | 2011-02-18 | Heart valve |
PCT/GB2012/000165 WO2012110767A2 (en) | 2011-02-18 | 2012-02-17 | Heart valve |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ614392A NZ614392A (en) | 2015-02-27 |
NZ614392B2 true NZ614392B2 (en) | 2015-05-28 |
Family
ID=
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