U.S. patent application number 12/120184 was filed with the patent office on 2009-11-19 for physiologically harmonized tricuspid annuloplasty ring.
This patent application is currently assigned to Edwards Lifesciences Corporation. Invention is credited to Alain Carpentier.
Application Number | 20090287303 12/120184 |
Document ID | / |
Family ID | 39590154 |
Filed Date | 2009-11-19 |
United States Patent
Application |
20090287303 |
Kind Code |
A1 |
Carpentier; Alain |
November 19, 2009 |
PHYSIOLOGICALLY HARMONIZED TRICUSPID ANNULOPLASTY RING
Abstract
A prosthetic tricuspid remodeling annuloplasty ring having two
free ends that are upturned in the inflow direction to help avoid
unnecessary leaflet abrasion. The free ends are desirably separated
across a gap that is large enough to reduce the risk of passing
sutures through the conductive system of the heart, yet not too
large that support of the septal leaflet of the tricuspid annulus
is degraded. The tricuspid ring may have four sequential segments
looking from the inflow side and extending in a clockwise direction
from a free end located adjacent the antero septal commissure after
implant. The ring may define an inflow bulge in the first segment
and/or an inflow bulge in the fourth segment that help the ring
conform to the natural bulges created by the adjacent aorta,
thereby reducing stress and the potential for ring dehiscence.
Desirably, the ring has variable flexibility, either gradual and/or
between or within different segments, so as to adapt or harmonize
its 3-dimensional shape to each individual patient and, therefore,
to significantly reduce the constraints on the annulus and adjacent
structures, particularly the leaflets and the conduction
tissue.
Inventors: |
Carpentier; Alain; (Paris,
FR) |
Correspondence
Address: |
EDWARDS LIFESCIENCES CORPORATION
LEGAL DEPARTMENT, ONE EDWARDS WAY
IRVINE
CA
92614
US
|
Assignee: |
Edwards Lifesciences
Corporation
Irvine
CA
|
Family ID: |
39590154 |
Appl. No.: |
12/120184 |
Filed: |
May 13, 2008 |
Current U.S.
Class: |
623/2.36 |
Current CPC
Class: |
A61F 2250/0019 20130101;
A61F 2250/0018 20130101; A61F 2/2445 20130101; A61F 2/2448
20130101; A61F 2/2442 20130101 |
Class at
Publication: |
623/2.36 |
International
Class: |
A61F 2/24 20060101
A61F002/24 |
Claims
1. A prosthetic tricuspid annuloplasty ring, comprising: a ring
body generally arranged in a plane and about an axis along an
inflow-outflow direction, the ring body being discontinuous so as
to define a first free end and a second free end separated across a
gap, the two free ends being bent out of the plane in an inflow
direction.
2. The prosthetic tricuspid annuloplasty ring of claim 1, wherein
the ring body defines a generally asymmetric ovoid shape and
extends in a clockwise direction from a first free end located
adjacent the antero-septal commissure when implanted, as seen
looking at the inflow side thereof, around a first segment, a
second segment, a third segment, and a fourth segment that
terminates in the second free end at a septal point, and wherein
the ring body has an arcuate bulge out of the plane toward the
inflow side at the first segment to accommodate an anatomical bulge
of the aorta into the tricuspid annulus.
3. The prosthetic tricuspid annuloplasty ring of claim 1, wherein
the ring body defines a generally asymmetric ovoid shape and
extends in a clockwise direction from a first free end located
adjacent the antero-septal commissure when implanted, as seen
looking at the inflow side thereof, around a first segment, a
second segment, a third segment, and a fourth segment that
terminates in the second free end at a septal point, and wherein
the ring body has an arcuate bulge out of the plane toward the
inflow side at the fourth segment.
4. The prosthetic tricuspid annuloplasty ring of claim 1, wherein
the ring body defines a generally asymmetric ovoid shape and
extends in a clockwise direction from a first free end located
adjacent the antero-septal commissure when implanted, as seen
looking at the inflow side thereof, around a first segment, a
second segment, a third segment, and a fourth segment that
terminates in the second free end at a septal point, and wherein
the ring body has a varying flexibility and the fourth segment is
relatively more flexible than the third segment.
5. The prosthetic tricuspid annuloplasty ring of claim 1, wherein
the ring body has a varying flexibility and is stiffer adjacent the
first free end than adjacent the second free end.
6. The prosthetic tricuspid annuloplasty ring of claim 1, wherein
the ring body has a varying flexibility comprising at least one
hinge point that is locally more flexible than adjacent
segments.
7. The prosthetic tricuspid annuloplasty ring of claim 1, wherein
the ring has a long dimension in millimeters, and the free ends are
separated by a distance of between about 40%-50% of the long
dimension.
8. The prosthetic tricuspid annuloplasty ring of claim 1, wherein
the two free ends are each bent to have an axial height of between
about 1-4 mm out of the plane.
9. A prosthetic tricuspid annuloplasty ring having a long dimension
in millimeters, comprising: an asymmetric generally ovoid ring body
generally arranged in a plane and about an axis along an
inflow-outflow direction and being discontinuous so as to define
two free ends, the ring body having a length and shape such that if
a first free end is implanted adjacent an antero septal commissure
of the tricuspid annulus the ring body conforms to the tricuspid
annulus and a second end is located adjacent a septal leaflet of
the tricuspid annulus, and the free ends are separated across a gap
having a dimension of between about 40%-50% of the long
dimension.
10. The prosthetic tricuspid annuloplasty ring of claim 9, wherein
the ring body extends in a clockwise direction from the first free
end, as seen looking at the inflow side thereof around a first
segment, a second segment, a third segment, and a fourth segment
that terminates in the second free end at a septal point, and
wherein the ring body has an arcuate bulge out of the plane toward
the inflow side at the first segment to accommodate an anatomical
bulge of the aorta into the tricuspid annulus.
11. The prosthetic tricuspid annuloplasty ring of claim 9, wherein
the ring body extends in a clockwise direction from the first free
end, as seen looking at the inflow side thereof, around a first
segment, a second segment, a third segment, and a fourth segment
that terminates in the second free end at a septal point, and
wherein the ring body has an arcuate bulge out of the plane toward
the inflow side at the fourth segment.
12. The prosthetic tricuspid annuloplasty ring of claim 9, wherein
the ring body has a varying flexibility and is stiffer adjacent the
first free end than adjacent the second free end.
13. The prosthetic tricuspid annuloplasty ring of claim 9, wherein
the ring body has a varying flexibility comprising at least one
hinge point that is locally more flexible than adjacent
segments.
14. A prosthetic tricuspid annuloplasty ring, comprising: an
asymmetric generally ovoid ring body generally arranged in a plane
and about an axis along an inflow-outflow direction with a first
free end located adjacent an antero-septal commissure when
implanted and a second free end located at a septal point, wherein
the ring body extends in a clockwise direction as seen looking at
an inflow side from the first free end around a first segment a
second segment, a third segment, and a fourth segment that
terminates in the second free end, and wherein the ring body has an
arcuate bulge out of the plane toward the inflow side at the first
segment so as to accommodate an anatomical bulge of the aorta into
the tricuspid annulus.
15. The prosthetic tricuspid annuloplasty ring of claim 14, wherein
the ring body an arcuate bulge out of the plane toward the inflow
side at the fourth segment.
16. The prosthetic tricuspid annuloplasty ring of claim 14, wherein
the ring body has a varying flexibility and is stiffer adjacent the
first free end than adjacent the second free end.
17. The prosthetic tricuspid annuloplasty ring of claim 16, wherein
the ring body has a varying flexibility comprising at least one
hinge point that is locally more flexible than adjacent
segments.
18. A prosthetic tricuspid annuloplasty ring, comprising: an
asymmetric generally ovoid ring body generally arranged in a plane
and about an axis along an inflow-outflow direction with a first
free end located adjacent an antero-septal commissure when
implanted and a second free end located at a septal point, wherein
the ring body extends in a clockwise direction as seen looking at
an inflow side from the first free end around a first segment, a
second segment, a third segment, and a fourth segment that
terminates in the second free end, and wherein the ring body has a
variable flexibility comprising at least one hinge point that is
locally more flexible than adjacent segments.
19. The prosthetic tricuspid annuloplasty ring of claim 18, wherein
the hinge point is located at the approximate midpoint of the ring
body.
20. The prosthetic tricuspid annuloplasty ring of claim 18, wherein
there are two hinge points located approximately diametrically
opposite one another so that the ring flexes generally in a plane.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to medical devices
and particularly to a tricuspid annuloplasty ring.
BACKGROUND OF THE INVENTION
[0002] In vertebrate animals, the heart is a hollow muscular organ
having four pumping chambers: the left and right atria and the left
and right ventricles, each provided with its own one-way valve. The
natural heart valves are identified as the aortic, mitral (or
bicuspid), tricuspid and pulmonary, and are each mounted in an
annulus comprising dense fibrous rings attached either directly or
indirectly to the atrial and ventricular muscle fibers. Each
annulus defines a flow orifice.
[0003] Heart valve disease is a widespread condition in which one
or more of the valves of the heart fails to function properly.
Diseased heart valves may be categorized as either stenotic,
wherein the valve does not open sufficiently to allow adequate
forward flow of blood through the valve, and/or incompetent,
wherein the valve does not close completely, causing excessive
backward flow of blood through the valve when the valve is closed.
Valve disease can be severely debilitating and even fatal if left
untreated.
[0004] Various surgical techniques may be used to repair a diseased
or damaged valve. In a valve replacement operation, the damaged
leaflets are excised and the annulus sculpted to receive a
replacement valve. Another less drastic method for treating
defective valves is through repair or reconstruction, which is
typically used on minimally calcified valves. The most widely used
repair technique is remodeling annuloplasty first proposed by the
same inventor in which the deformed valve annulus is reshaped by
attaching a prosthetic annuloplasty repair segment or ring to the
valve annulus. The annuloplasty ring is designed to support the
functional changes that occur during the cardiac cycle: maintaining
coaptation and valve integrity to prevent reverse flow while
permitting good hemodynamics during forward flow.
FIELD OF THE INVENTION
[0005] The present invention relates generally to medical devices
and particularly to a tricuspid annuloplasty ring.
BACKGROUND OF THE INVENTION
[0006] In vertebrate animals, the heart is a hollow muscular organ
having four pumping chambers: the left and right atria and the left
and right ventricles, each provided with its own one-way valve. The
natural heart valves are identified as the aortic, mitral (or
bicuspid), tricuspid and pulmonary, and are each mounted in an
annulus comprising dense fibrous rings attached either directly or
indirectly to the atrial and ventricular muscle fibers. Each
annulus defines a flow orifice.
[0007] Heart valve disease is a widespread condition in which one
or more of the valves of the heart fails to function properly.
Diseased heart valves may be categorized as either stenotic,
wherein the valve does not open sufficiently to allow adequate
forward flow of blood through the valve, and/or incompetent,
wherein the valve does not close completely, causing excessive
backward flow of blood through the valve when the valve is closed.
Valve disease can be severely debilitating and even fatal if left
untreated.
[0008] Various surgical techniques may be used to repair a diseased
or damaged valve. In a valve replacement operation, the damaged
leaflets are excised and the annulus sculpted to receive a
replacement valve. Another less drastic method for treating
defective valves is through repair or reconstruction, which is
typically used on minimally calcified valves. The most widely used
repair technique is remodeling annuloplasty first proposed by the
same inventor in which the deformed valve annulus is reshaped by
attaching a prosthetic annuloplasty repair segment or ring to the
valve annulus. The annuloplasty ring is designed to support the
functional changes that occur during the cardiac cycle: maintaining
coaptation and valve integrity to prevent reverse flow while
permitting good hemodynamics during forward flow.
[0009] The annuloplasty ring typically comprises an inner substrate
of a metal such as rods or bands of stainless steel or titanium, or
a flexible material such as silicone rubber or Dacron cordage,
covered with a biocompatible fabric or cloth to allow the ring to
be sutured to the fibrous annulus tissue. Annuloplasty rings may be
stiff or flexible, split or continuous, and may have a variety of
shapes, including circular, U-shaped, C-shaped, or kidney-shaped.
Examples are seen in U.S. Pat. Nos. 5,041,130, 5,104,407,
5,201,880, 5,258,021, 5,607,471 and, 6,187,040 B1. Whether totally
flexible, rigid, or semi-rigid, annuloplasty rings have sometimes
been associated with a certain degree of arrhythmia or a 10% to 15%
incidence at 10 years of ring dehiscence and/or conduction tissue
disturbance. The present invention is intended to reduce the
complications.
[0010] For the purposes of anatomic orientation, please refer to
FIG. 1, which is a schematic representation of the AV junctions
within the heart and the body in the left anterior oblique
projection. The body is viewed in the upright position and has 3
orthogonal axes: superior-inferior, posterior-anterior, and
right-left. Traditional nomenclature for the AV junctions derives
from a surgically distorted view, placing the valvular rings in a
single horizontal plane with antero-posterior and right-left
lateral coordinates. The descriptive terms used, however, are
anatomically inaccurate. An accurate account of the coordinates of
the valvular orifices is provided by the simple expedient of
relating appropriately the view obtained in left anterior oblique
projection to the supero-inferior and antero-posterior coordinates
of the body.
[0011] FIG. 2 is a cutaway view of the heart from the front, or
anterior, perspective, with most of the primary structures marked.
As is well known, the pathway of blood in the heart is from the
right atrium to the right ventricle through the tricuspid valve, to
and from the lungs, and from the left atrium to the left ventricle
through the mitral valve. The present application has particular
relevance to the repair of the tricuspid valve, which regulates
blood flow between the right atrium and right ventricle, although
certain aspects may apply to repair of other of the heart valves.
The tricuspid and mitral valves together define the
atrioventricular (AV) junctions.
[0012] As seen in FIG. 2, four structures embedded in the wall of
the heart conduct impulses through the cardiac muscle to cause
first the atria then the ventricles to contract. These structures
are the sinoatrial node (SA node), the atrioventricular node (AV
node), the bundle of His, and the Purkinje fibers. On the rear wall
of the right atrium is a barely visible knot of tissue known as the
sinoatrial, or SA node. This tiny area is the control of the
heart's pacemaker mechanism. Impulse conduction normally starts in
the SA node. It generates a brief electrical impulse of low
intensity approximately 72 times every minute in a resting adult.
From this point the impulse spreads out over the sheets of tissue
that make up the two atria, exciting the muscle fibers as it does
so. This causes contraction of the two atria and thereby thrusts
the blood into the empty ventricles. The impulse quickly reaches
another small specialized knot of tissue known as the
atrioventricular, or AV node, located between the atria and the
ventricles. This node delays the impulse for about 0.07 seconds,
which is exactly enough time to allow the atria to complete their
contractions. When the impulses reach the AV node, they are relayed
by way of the several bundles of His and Purkinje fibers to the
ventricles, causing them to contract. As those of skill in the art
are aware, the integrity and proper functioning of the conductive
system of the heart is critical for good health.
[0013] FIG. 3 is a schematic view of the tricuspid valve orifice
seen from its inflow side (from the right atrium), with the
peripheral landmarks labeled as: antero septal commissure, anterior
leaflet, posterior commissure, posterior leaflet, postero septal
commissure, and septal leaflet. Contrary to traditional orientation
nomenclature, the tricuspid valve is nearly vertical, as reflected
by these sector markings. From the same viewpoint, the tricuspid
valve 20 is shown surgically exposed in FIG. 4 with an annulus 22
and three leaflets 24a, 24b, 24c extending inward into the flow
orifice. Chordae tendineae 26 connect the leaflets to papillary
muscles located in the RV to control the movement of the leaflets.
The tricuspid annulus 22 is an ovoid-shaped fibrous ring at the
base of the valve that is less prominent than the mitral annulus,
but larger in circumference.
[0014] Reflecting their true anatomic location, the three leaflets
in FIG. 4 are identified as septal 24a, anterior 24b, and posterior
(or "mural") 24c. The leaflets join together over three prominent
zones of apposition, and the peripheral intersections of these
zones are usually described as commissures 28. The leaflets 24 are
tethered at the commissures 28 by the fan-shaped chordae tendineae
26 arising from prominent papillary muscles originating in the
right ventricle. The septal leaflet 24a is the site of attachment
to the fibrous trigone, the fibrous "skeletal" structure within the
heart. The anterior leaflet 24b, largest of the 3 leaflets, often
has notches. The posterior leaflet 24c, smallest of the 3 leaflets,
usually is scalloped.
[0015] The ostium 30 of the right coronary sinus opens into the
right atrium, and the tendon of Todaro 32 extends adjacent thereto.
The AV node 34 and the beginning of the bundle of His 36 are
located in the supero-septal region of the tricuspid valve
circumference. The AV node 34 is situated directly on the right
atrial side of the central fibrous body in the muscular portion of
the AV septum, just superior and anterior to the ostium 30 of the
coronary sinus 30. Measuring approximately 1.0 mm.times.3.0
mm.times.6.0 mm, the node is flat and oval. The AV node 34 is
located at the apex of the triangle of Koch 38, which is formed by
the tricuspid annulus 22, the ostium 30 of the coronary sinus, and
the tendon of Todaro 32. The AV node 34 continues on to the bundle
of His 36, typically via a course inferior to the commissure 28
between the septal 24a and anterior 24b leaflets of the tricuspid
valve; however, the precise course of the bundle of His 36 in the
vicinity of the tricuspid valve may vary. Moreover, the location of
the bundle of His 36 may not be readily apparent from a resected
view of the right atrium because it lies beneath the annulus
tissue.
[0016] The triangle of Koch 30 and tendon of Todaro 32 provide
anatomic landmarks during tricuspid valve repair procedures. A
major factor to consider during surgery is the proximity of the
conduction system (AV node 34 and bundle of His 36) to the septal
leaflet 24a. Of course, surgeons must avoid placing sutures too
close to or within the AV node 34. C-shaped rings are good choices
for tricuspid valve repairs because they allow surgeons to position
the break in the ring adjacent the AV node 34, thus avoiding the
need for suturing at that location.
[0017] A rigid C-shaped ring of the prior art is the
Carpentier-Edwards Classic.RTM. Tricuspid Annuloplasty Ring sold by
Edwards Lifesciences Corporation of Irvine, Calif., which is seen
in FIGS. 5A and 5B. Although not shown, the planar ring 40 has an
inner titanium core (not shown) covered by a layer of silicone and
fabric. Rings for sizes 26 mm through 36 mm in 2 mm increments have
outside diameters (OD) between 31.2-41.2 mm, and inside diameters
(ID) between 24.3-34.3 mm. These diameters are taken along the
"diametric" line spanning the greatest length across the ring
because that is the conventional sizing parameter. A gap G between
free ends 42a, 42b in each provides the discontinuity to avoid
attachment over the AV node 34. The gap G for the various sizes
ranges between about 5-8 mm, or between about 19%-22% of the
labeled size. As seen in the implanted view of FIG. 6, the gap G is
sized just larger than the AV node 34. Despite this clearance, some
surgeons are uncomfortable passing sutures so close to the
conductive AV node 34, particularly considering the additional
concern of the bundle of His 36.
[0018] A flexible C-shaped tricuspid ring is sold under the name
Sovering.TM. by Sorin Biomedica Cardio S.p.A. of Via Crescentino,
Italy. The Sovering.TM. is made with a radiopaque silicone core
covered with a knitted polyester (PET) fabric so as to be totally
flexible. Rings for sizes 28 mm through 36 mm in 2 mm increments
have outside diameters (OD) between 33.8-41.8 mm, and inside
diameters (ID) between 27.8-35.8 mm. As with other tricuspid rings,
a gap between the free ends provides a discontinuity to avoid
attachment over the AV node. The gap for the various sizes ranges
of the Sovering.TM. ranges between about 18-24 mm, or between about
60%-70% of the labeled size. Although this gap helps avoid passing
sutures close to the conductive AV node 34 and bundle of His 36,
the ring is designed to be attached at the commissures on either
side of the septal leaflet and thus no support is provided on the
septal side.
[0019] Despite numerous designs presently available or proposed in
the past, there is a need for a prosthetic tricuspid ring that
better harmonizes with the anatomical and physiologic features of
the tricuspid annulus, and in particular for a prosthetic tricuspid
ring that better fits the contours of the tricuspid annulus and
presents selective flexibility to reduce the stress in the
attachment sutures, while at the same time reduces the risk of
inadvertently passing a suture through the critical physiologic
structures within the heart that conduct impulses.
SUMMARY OF THE INVENTION
[0020] The present invention provides a tricuspid annuloplasty ring
including a ring body generally arranged in a plane and about an
axis along an inflow-outflow direction, the ring body being
discontinuous so as to define a first free end and a second free
end separated across a gap, the two free ends being bent out of the
plane in an inflow direction. Preferably, the two free ends are
flexible and can be bent to have an axial height of between about
1-4 mm out of the plane.
[0021] Preferably, the ring body defines a generally asymmetric
ovoid shape and extends in a clockwise direction from a first free
end located adjacent the antero-septal commissure when implanted,
as seen looking at the inflow side thereof, around a first segment,
a second segment, a third segment, and a fourth segment that
terminates in the second free end at a septal point. In one
embodiment the ring body has an arcuate bulge out of the plane
toward the inflow side at the first segment to accommodate an
anatomical bulge of the aorta into the tricuspid annulus. In a
further embodiment, the ring body has an arcuate bulge out of the
plane toward the inflow side at the fourth segment to accommodate
an anatomical bulge of the aorta into the tricuspid annulus. Still
further, the ring body desirably has a varying flexibility and is
stiffer adjacent the first free end than adjacent the second free
end, or comprises at least one hinge point that is locally more
flexible than adjacent segments. In one preferred construction, the
ring body comprises a plurality of concentric peripheral bands
having an axial dimension which is larger adjacent the first free
end than adjacent the second free end. In a preferred embodiment,
the ring has a long dimension in millimeters, and the free ends are
separated by a distance of between about 40%-50% of the long
dimension.
[0022] In accordance with another aspect of the invention, a
prosthetic tricuspid annuloplasty ring having a long dimension in
millimeters, comprises an asymmetric generally ovoid ring body. The
ring body is generally arranged in a plane and about an axis along
an inflow-outflow direction and is discontinuous so as to define
two free ends. The ring body has a length and shape such that if a
first free end is implanted adjacent an antero septal commissure of
the tricuspid annulus, the ring body conforms to the tricuspid
annulus and a second end is located adjacent a septal leaflet
thereof, and the free ends are separated across a gap having a
dimension of between about 40%-50% of the long dimension.
[0023] In the ring having a gap of between 40%-50% of the long
dimension, the ring body extends in a clockwise direction from the
first free end, as seen looking at the inflow side thereof around a
first segment, a second segment, a third segment, and a fourth
segment that terminates in the second free end at a septal point.
In one embodiment the ring body has an arcuate bulge out of the
plane toward the inflow side at the first segment to accommodate an
anatomical bulge of the aorta into the tricuspid annulus. In a
further embodiment, the ring body has an arcuate bulge out of the
plane toward the inflow side at the fourth segment. Still further,
the ring body desirably has a varying flexibility and is stiffer
adjacent the first free end than adjacent the second free end, or
comprises at least one hinge point that is locally more flexible
than adjacent segments.
[0024] In accordance with a still further aspect of the invention,
a prosthetic tricuspid annuloplasty ring comprises an asymmetric
generally ovoid ring body generally arranged in a plane and about
an axis along an inflow-outflow direction with a first free end
located adjacent an antero-septal commissure when implanted and a
second free end located at a septal point. The ring body extends in
a clockwise direction as seen looking at an inflow side from the
first free end around a first segment, a second segment, a third
segment, and a fourth segment that terminates in the second free
end. The ring body has an arcuate bulge out of the plane toward the
inflow side at the first segment so as to accommodate an anatomical
bulge of the aorta into the tricuspid annulus. The ring body may
also have an arcuate bulge out of the plane toward the inflow side
at the fourth segment. Desirably, the ring body has a varying
flexibility and the fourth segment is relatively more flexible than
the third segment. The first free end may also be stiffer than the
second free end. Alternatively, the varying flexibility comprises
at least one hinge point that is locally more flexible than
adjacent segments.
[0025] In a further embodiment, and prosthetic tricuspid
annuloplasty ring is provided that comprises an asymmetric
generally ovoid ring body generally arranged in a plane and about
an axis along an inflow-outflow direction with a first free end
located adjacent an antero-septal commissure when implanted and a
second free end located at a septal point. The ring body extends in
a clockwise direction as seen looking at an inflow side from the
first free end around a first segment, an second segment, a third
segment, and a fourth segment that terminates in the second free
end. The ring body has a variable flexibility comprising at least
one hinge point that is locally more flexible than adjacent
segments. Desirably, the hinge point is located at the approximate
midpoint of the ring body. Alternatively, there are two hinge
points located approximately diametrically opposite one another so
that the ring flexes generally in a plane.
[0026] A further understanding of the nature and advantages of the
invention will become apparent by reference to the remaining
portions of the specification and drawings.
DESCRIPTION OF THE DRAWINGS
[0027] Features and advantages of the present invention will become
appreciated as the same become better understood with reference to
the specification, claims, and appended drawings wherein:
[0028] FIG. 1 is a schematic representation of the AV junctions
within the heart and the body in the left anterior oblique
projection;
[0029] FIG. 2 is a cutaway view of the heart from the front, or
anterior, perspective;
[0030] FIG. 3 is a schematic plan view of the tricuspid annulus
with typical orientation directions noted as seen from the inflow
side;
[0031] FIG. 4 is a plan view of the native tricuspid valve and
surrounding anatomy from the inflow side;
[0032] FIGS. 5A and 5B are plan and septal elevational views,
respectively, of a planar tricuspid annuloplasty ring of the prior
art;
[0033] FIG. 6 is a plan view of the native tricuspid valve and
surrounding anatomy from the inflow side with the annuloplasty ring
of FIGS. 5A-5B implanted;
[0034] FIGS. 7A-7C are plan and septal and anterior elevational
views, respectively, of an exemplary tricuspid annuloplasty ring of
the present invention illustrating its free ends bent toward the
inflow side and an antero-superior bulge;
[0035] FIG. 8 is a plan view of the native tricuspid valve and
surrounding anatomy from the inflow side with the annuloplasty ring
of FIGS. 7A-7B implanted;
[0036] FIGS. 9A-9C are plan and septal and anterior elevational
views, respectively, of the exemplary tricuspid annuloplasty ring
of FIGS. 7A-7B with portions cutaway to show internal details;
and
[0037] FIGS. 10A-10D are sectional views taken along respective
section lines in FIG. 9A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0038] The present invention provides an improved tricuspid
annuloplasty ring that better conforms to the native annulus and is
shaped to protect certain features of the surrounding anatomy. The
ring of the present invention is designed to support a majority of
the tricuspid annulus without risking injury to the leaflet tissue
and heart's conductive system, such as the AV node 34 and bundle of
His 36 (see FIG. 4). Additionally, the present ring is contoured to
better approximate the three-dimensional shape of the tricuspid
annulus; specifically, the ring is substantially planar but
includes a bulge in the inflow direction at the location of the
bulge created by the adjacent aorta. The bulge helps reduce stress
between the ring and surrounding tissue, and thus the potential for
tearing or ring dehiscence.
[0039] Another feature that matches the present tricuspid ring with
the physiological features of the annulus is a variable flexibility
from a relatively stiff first segment to a relatively flexible
fourth segment. This varying flexibility permits the ring to adapt
(harmonize) its motion and 3-dimensional shape to that of the
annulus, rather than impose its own motion and 3-D geometry thereto
which tends to increase the risk of ring dehiscence. In particular,
the motion of the tricuspid annulus during systole-diastole is
believed to exert some torsional forces on the implanted ring, and
the variable flexibility accommodates such torques. Moreover,
localized points of flexibility or "hinges" around the ring as
described herein may best conform and harmonize the physical
properties of the ring to the annulus motion, while at the same
time providing the needed corrective support.
[0040] It should also be understood that certain features of the
present tricuspid ring might also be applicable and beneficial to
rings for other of the heart's annuluses. For instance, the present
ring includes upturned or bent free ends that help reduce abrasion
on the adjacent leaflets. The same structure might be used in a
discontinuous ring for the mitral valve annulus.
[0041] The term "axis" in reference to the illustrated ring, and
other non-circular or non-planar rings, refers to a line generally
perpendicular to the ring that passes through the area centroid of
the ring when viewed in plan view. "Axial" or the direction of the
"axis" can also be viewed as being parallel to the direction of
blood flow within the valve orifice and thus within the ring when
implanted therein. Stated another way, the implanted tricuspid ring
orients about a central flow axis aligned along an average
direction of blood flow through the tricuspid annulus. Although the
rings of the present invention are 3-dimensional, portions thereof
are planar and lie perpendicular to the flow axis.
[0042] FIGS. 7A-7C illustrate, in plan and septal and anterior
elevational views, a tricuspid ring 50 of the present invention
having a ring body 52 generally arranged about an axis 54 and being
discontinuous so as to define two free ends 56a, 56b. The axis 54
in FIG. 7A lies at the centroid of the ring or along of the axis of
blood flow through the ring 50 when implanted, and it will be
understood that the relative directions up and down are as viewed
in FIG. 7B. Using this convention, the ring 50 is designed to be
implanted in a tricuspid annulus such that blood will flow in the
downward direction.
[0043] As seen in FIGS. 7A-7C and also in FIGS. 9A-9C, the ring
body 52 is substantially asymmetric and ovoid with the first free
end 56a located adjacent the antero-septal commissure (see FIG. 3).
The ring body 52 extends in a clockwise direction, as seen looking
at the inflow side in FIG. 7A, around a first segment 60a
corresponding to the aortic part of the anterior leaflet, a second
segment 60b corresponding to the remaining part of the anterior
leaflet and ending at the postero septal commissure, a third
segment 60c from the postero septal commissure to a line 61 part
way along the septal leaflet, and a fourth segment 60d that
terminates in the second free end 56b at a septal point. The
nomenclature for these segments is taken from the standard
anatomical nomenclature around the tricuspid annulus as seen in
FIG. 3.
[0044] The precise relative dimensions of the segments may vary,
but they are generally as indicated in the view of FIG. 7A. That
is, the second segment 60b is the largest, followed by the first
segment 60a, and then the smaller third segment 60c and fourth
segment 60d. It should be further noted that the term "asymmetric"
means that there are no planes of symmetry through the ring body 52
looking from the inflow side, and "ovoid" means generally shaped
like an egg with a long axis and a short axis, and one long end
larger than the other.
[0045] FIG. 8 shows the tricuspid ring 50 in plan view after having
been implanted or otherwise affixed to a tricuspid valve. To
quantify relative to the native anatomy, the combined first and
second segments 60a and 60b extend approximately around the
tricuspid annulus between the two commissures 28 that bookend the
septal leaflet 24a. Accordingly, a pair of commissure markers 62a,
62b on the exterior of the ring body 52 facilitate implantation by
registering the ring 50 with respect to the commissures 28. The
markers 62a, 62b are typically radially-oriented colored thread
fastened to a fabric covering on the ring.
[0046] A majority of the ring body 52 is planar except for the free
ends 56a, 56b which are upturned and the first segment 60a and a
part of fourth segment 60d that are bowed upward. (To repeat, the
"up" direction is merely for purpose of clarity herein and is
synonymous with the inflow direction). As with existing rings,
sizes 26 mm through 36 mm in 2 mm increments are available having
outside diameters (OD) between 31.2-41.2 mm, and inside diameters
(ID) between 24.3-34.3 mm. Again, these diameters are taken along
the "diametric" line spanning the greatest length across the ring,
as seen in FIG. 5A. It should be mentioned that the present
invention is not limited to the aforementioned range of sizes, and
larger rings of 38 or 40 mm OD are also possible, for example.
[0047] A gap G' between the two free ends 56a, 56b is substantially
larger than in certain rings of the prior art to reduce the risk of
suturing into the AV node or bundle of His, and to accommodate
variations in anatomy and location of the bundle of His. In
particular, the gap G' is preferably between about 40%-50% of the
labeled size, preferably between about 43-45%. In one
configuration, the gap G' is about 40% of the size of the long axis
of the ring, which is typically the labeled size in millimeters. In
absolute terms, the gap G' is desirably between about 10-18 mm,
depending on the labeled size. For instance, the gap G' is
preferably about 13.6 mm for a size 34 ring (about 40% of the
labeled size). On the other hand, the gap G' is not too large to
reduce the effective support for the septal leaflet 24a.
Preferably, the fourth segment 60d of the ring 50 of the present
invention extends at least half of the way around the septal
leaflet 24a.
[0048] In a preferred embodiment, the gap G' is larger than the gap
G in the rigid C-shaped Carpentier-Edwards Classic.RTM. Tricuspid
Annuloplasty Ring, seen in FIGS. 5A and 5B. The gap G for the
various sizes of Classic.RTM. Rings ranges between about 5-8 mm, or
between about 19%-22% of the labeled size. At the same time, the
gap G' of the ring of the present invention is larger than the gap
in the flexible C-shaped Sovering.TM. tricuspid ring from Sorin
Biomedica Cardio S.p.A. The gap for the various sizes of the
Sovering.TM. ranges between about 18-24 mm, or between about
60%-70% of the labeled size. Therefore, the gap G' of the ring of
the present invention is preferably greater than 8 mm and less than
18 mm, or is between about 23%-59% of the labeled size (typically
equal to the dimension in millimeters of the long axis of the
ring).
[0049] The free ends 56a, 56b of the exemplary ring 50 are upturned
in the inflow direction so as to help reduce abrasion on the
adjacent leaflets (septal, or both septal and antero-superior).
Prior rings that are not completely flexible terminate in ends that
are extensions of the ring periphery, that is, they do not deviate
from the paths that the adjacent segments of the ring follow. As
will be explained below, the present ring 50 desirably includes a
core member that provides at least some rigidity and structural
support for the annulus. The upturned ends 56a, 56b present curved
surfaces that the constantly moving leaflets might repeatedly
contact, as opposed to point surfaces so that forcible abrasion of
the moving leaflets in contact with the ends of the ring is
avoided.
[0050] As seen in FIGS. 7B and 7C, the exemplary ring 50 also
includes an upward arcuate bow or bulge 64 in the first segment
60a, and another upward bulge 65 in the fourth segment 60d. The
"aortic" bulge 64 accommodates a similar contour of the tricuspid
annulus due to the external presence of the aorta and desirably
extends from near the first free end 56a along first segment 60a to
a location that corresponds to the end of the aortic part of the
anterior leaflet. Prior tricuspid rings are substantially planar,
and if at all rigid they necessarily deform the annulus to some
extent at this location. The aortic bulge 64 helps reduce stress
upon implant and concurrently reduces the chance of dehiscence, or
the attaching sutures pulling out of the annulus. The axial height
h.sub.b of the aortic bulge 64 above the nominal top surface of the
ring body 52, as indicated in FIG. 9C, is between about 3-9 mm,
preferably about 6 mm. The "septal" bulge 65 conforms to the slight
bulging of the septal leaflet attachment in this area. The axial
height h.sub.s of the septal bulge 65 above the nominal top surface
of the ring body 52, as indicated in FIG. 9B, is between about 2 to
4 mm. These two bulges 64, 65 provide a "saddle shape" to the ring
body 52.
[0051] Now with particular reference to FIGS. 9A-9C and 10A-10D,
the tricuspid ring 50 of the present invention is seen partially
cutaway and in sections to illustrate further exemplary features.
As seen best in the cutaway portion of FIG. 9B, the ring body 52
preferably comprises an inner core 70 encompassed by an elastomeric
interface 72 and an outer fabric covering 74.
[0052] The inner core 70 extends substantially around the entire
periphery of the ring body 52 and is a relatively rigid material
such as stainless steel, titanium, Elgiloy (an alloy primarily
including Ni, Co, and Cr), Nitinol, and even certain polymers. The
term "relatively rigid" refers to the ability of the core 70 to
support the annulus without substantial deformation, and implies a
minimum elastic strength that enables the ring to maintain its
original shape after implant even though it may flex somewhat.
Indeed, as will be apparent, the ring desirably possesses some
flexibility around its periphery. To further elaborate, the core 70
would not be made of silicone, which easily deforms to the shape of
the annulus and therefore will not necessarily maintain its
original shape upon implant.
[0053] The elastomeric interface 72 may be silicone rubber molded
around the core 70, or a similar expedient. The elastomeric
interface 72 provides bulk to the ring for ease of handling and
implant, and permits passage of sutures though not significantly
adding to the anchoring function of the outer fabric covering 74.
The fabric covering 74 may be any biocompatible material such as
Dacron.RTM. (polyethylene terepthalate). As seen in FIGS. 10A-10C,
the elastomeric interface 72 and fabric covering 74 project
outwards along the outside of the ring 50 to provide a platform
through which to pass sutures.
[0054] As mentioned above, the ring 50 of the present invention may
possess a varying flexibility around its periphery. In general, the
ring 50 is desirably stiffer adjacent the first free end 56a than
adjacent the second free end 56b, and preferably has a gradually
changing degree of flexibility for at least a portion in between.
For instance, the first segment 60a may be relatively stiff while
the remainder of the ring body 52 gradually becomes more flexible
through the second segment 60b, third segment 60c, and fourth
segment 60d. In a preferred embodiment, the fourth segment 60d is
more flexible than the third segment 60c.
[0055] With reference to FIG. 7A, the reader will appreciate that
the flexibility of the fourth segment 60d accommodates the inward
movement of the annulus in that sector from fluid dynamic closing
forces on the valve, and therefore reduces the chance of
dehiscence. More particularly, radial forces exerted on the ring in
the vertical direction, or along the small axis, will act on the
flexible fourth segment 60d and proportionately bend it inward, as
indicated in phantom. This reduction in the antero-septal ring
dimension, in turn, will reduce tension on the native valve
leaflets that pull inward from valve closing forces. Tests have
been conducted to determine the amount of force and movement
associated with the septal aspect of the tricuspid annulus in both
systole and diastole. Consequently, a preferred flexibility for the
fourth segment 60d has been determined and quantified in terms of
the amount of desirable deformation under a given load. In one
embodiment, the flexibility of the fourth segment 60d is such that
it deforms inward by about 10% of the antero-septal (small axis)
ring dimension under maximum load, typically resulting from right
ventricular pressures of up to 70 mm Hg. In contrast, left
ventricular pressures of up to 120 mm Hg are handled by a more
robust mitral annulus. The tricuspid annulus is more fragile and
implanted annuluplasty rings are somewhat more prone to
dehiscence.
[0056] Another potential configuration of variable flexibility
consists of one or more points of localized flexibility, or "hinge
points," that may supplement the aforementioned gradually changing
stiffness or be incorporated into an otherwise constant stiffness
ring. The locations of the contemplated hinges are best described
with reference to FIGS. 7A and 7B.
[0057] A central hinge created by an area of the ring body 52 that
is locally more flexible than adjacent sectors is desirably located
mid-way along the second segment 60b, as indicated by a hinge line
66. This hinge is located approximately at the center of the length
of the ring body 52, and permits the segments on either side to
flex or twist with respect to one another. Alternatively, two
generally diametrically-opposed hinge points indicated by hinge
lines 61 and 67 may be provided. These hinges are located at the
upward bulges 64, 65 in the ring body 52, and provide "saddle"
flexibility so that the ring flexes generally in a plane
intersecting the bulges. A ring according to the present invention
may have one or more of these hinges. Also, as mentioned above, the
discrete hinges or points of flexibility may be incorporated into
rings having constant or variable flexibility, as described above.
Finally, though 3-dimensional rings are shown, the several
embodiments of flexibility described herein may also be provided in
a flat, planar tricuspid ring, and with or without the increase gap
between the free ends.
[0058] In one exemplary construction, the ring body includes a core
70 made of a plurality of concentric peripheral bands having an
axial dimension which is larger adjacent the first free end 56a
than adjacent the second free end 56b. Sectional FIGS. 10A-10C
illustrate this embodiment. The core 70 in the first segment 60a
(and possibly in a portion of the second segment 60b) is as seen in
FIG. 10A, with six (6) concentric bands of a material such as
Elgiloy. In the section of FIG. 10B, which is taken through the
second segment 60b, a section of the core 701 still comprises six
concentric bands, but its axial height is reduced relative to the
height of the core as seen in FIG. 10A. Finally, FIG. 10C shows a
section through the third segment 60c wherein a further section of
the core 70'' is further reduced in height but also only comprises
four (4) concentric bands, with two of the bands having terminated
or tapered off somewhere between sections 10B and 10C. Of course,
this construction is entirely exemplary and the core 70 could also
be made of a single integral member that gradually tapers down in
size, among other alternatives. Several other alternatives are
disclosed in U.S. Pat. No. 5,104,407 to Lam, et al., the disclosure
of which is expressly incorporated herein by reference.
[0059] FIG. 10D shows the internal structure of the ring body 52 at
the second end 56b. The core 70 is shown bending upward into close
proximity with the extreme tip of the free end 56b, though it is
protected by the elastomeric interface 72 and the outer fabric
covering 74. Desirably, the core 70 has its greatest flexibility at
this location, which is mid-way around the septal leaflet side of
the tricuspid annulus. The upward bend of the core 70 and ring body
52 desirably makes an angle .theta. of between
45.degree.-90.degree., preferably greater than 60.degree..
Furthermore, the axial height h.sub.e, as indicated in FIG. 9C, of
the free ends 56a, 56b above the nominal top surface of the ring
body 52 is between about 1-4 mm, preferably about 2 mm, and
preferably the two free ends project upward the same distance
(although such a configuration is not an absolute requirement).
Because of the flexibility of the ring body 52 at the second end
56b, there is a reduction in the antero-septal dimension of the
ring depending on the load applied by the annulus in the small axis
(vertical) dimension.
[0060] While the foregoing is a complete description of the
preferred embodiments of the invention, various alternatives,
modifications, and equivalents may be used. Moreover, it will be
obvious that certain other modifications may be practiced within
the scope of the appended claims.
* * * * *