U.S. patent application number 09/746431 was filed with the patent office on 2002-01-31 for heart valve holder for constricting the valve commissures and methods of use.
Invention is credited to Ekholm, C. Roger, Jackman, Jerry L., Newborg, Steve, Stobie, Robert, Ton-That, Cuong.
Application Number | 20020013621 09/746431 |
Document ID | / |
Family ID | 27090199 |
Filed Date | 2002-01-31 |
United States Patent
Application |
20020013621 |
Kind Code |
A1 |
Stobie, Robert ; et
al. |
January 31, 2002 |
Heart valve holder for constricting the valve commissures and
methods of use
Abstract
An improved holder, system and method for implanting a
tissue-type prosthetic heart mitral valve that constricts the
commissure posts of the valve and allows the user to detach the
handle of the holder prior to withdrawing the holder itself. The
ability to remove the handle allows a surgeon greater access to
suturing the prosthetic valve to the mitral annulus. The holder may
include two relatively movable plates, one of which attaches to the
valve sewing on the inflow end of the valve ring and the other
which attaches via sutures to the valve commissures on the outflow
end. Separation of the plates places the sutures in tension and
constricts the commissures. An adjusting member or adapter is
interposed between the handle and holder to enable separation of
the two plates and removal of the handle. The adjusting member or
adapter may be packaged with the valve and holder combination, or
may be sold as a separate unit, possibly with the handle, so that
prior art holders can be retrofit.
Inventors: |
Stobie, Robert; (Mission
Viejo, CA) ; Jackman, Jerry L.; (Tustin, CA) ;
Ton-That, Cuong; (Irvine, CA) ; Ekholm, C. Roger;
(Rancho Santa Margarita, CA) ; Newborg, Steve;
(Riverside, CA) |
Correspondence
Address: |
Debra D. Condino, Reg. no. 31,007
Edwards Lifesciences LLC
Law Dept.
One Edwards Way
Irvine
CA
92614
US
|
Family ID: |
27090199 |
Appl. No.: |
09/746431 |
Filed: |
December 21, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09746431 |
Dec 21, 2000 |
|
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|
09626570 |
Jul 27, 2000 |
|
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Current U.S.
Class: |
623/2.11 ;
606/108 |
Current CPC
Class: |
A61F 2/2427
20130101 |
Class at
Publication: |
623/2.11 ;
606/108 |
International
Class: |
A61F 002/24; A61F
011/00 |
Claims
What is claimed is:
1. A holder for a tissue-type prosthetic mitral heart valve
attachable to a surgical delivery handle, the heart valve having an
inflow end and an outflow end and a flow axis therebetween, the
valve including an annular suture ring at the inflow end and
radially flexible commissure posts circumferentially-spaced around
the outflow end that support occluding tissue surfaces of the
valve, comprising: a commissure post constriction mechanism
releasably attached to the sewing ring at the inflow end of the
valve, the mechanism adapted to constrict the valve commissure
posts radially inward from a relaxed position to a constricted
position when actuated by the delivery handle, and a retaining
mechanism that retains the commissure post constriction mechanism
in the constricted position after the delivery handle is
removed.
2. The holder of claim 1 wherein the commissure post constriction
mechanism comprises: a valve abutment portion sized and shaped to
abut the inflow end of the valve; an adjusting portion coupled to
the abutment portion opposite the valve and able to move with
respect to the abutment portion; and one or more filaments attached
to the adjusting portion and coupled to the commissure posts that
constrict the commissure posts radially inwardly upon movement of
the adjusting portion with respect to the abutment portion.
3. The holder of claim 2 wherein the commissure post constriction
mechanism further comprises: an adjusting member coupled to the
adjusting portion and adapted to move the adjusting portion with
respect to the abutment portion.
4. The holder of claim 3 wherein the adjusting member is externally
threaded, the adjusting portion including a threaded aperture for
receiving the external threads of the adjusting member and being
open to the abutment portion, such that upon advancement into the
threaded aperture the threaded adjusting member contacts the
abutment portion and forces the adjusting portion away from the
abutment portion.
5. The holder of claim 4 wherein the valve abutment portion has a
generally planar shape, and the adjusting portion has a
substantially complementary planar shape to the valve abutment
portion with the threaded aperture extending through an upstanding
boss in the center thereof.
6. The holder of claim 4 wherein the adjusting member has a central
longitudinal threaded bore sized to receive the threaded end of the
handle.
7. The holder of claim 6 wherein the adjusting member and the
threaded aperture in the adjusting portion cooperate to form the
retaining mechanism wherein the frictional resistance to rotation
therebetween is greater than the frictional resistance to rotation
between the threaded end of the handle and the threaded bore of the
adjusting member.
8. The holder of claim 7 wherein the adjusting member and the
threaded aperture in the adjusting portion are each made of a
polymer, and the threaded end of the handle is metal.
9. The holder of claim 4 wherein the adjusting member and the
adjusting portion include interfering structures that engage upon
advancement of the adjusting member into the threaded aperture of
the adjusting portion to prevent reversal of the adjusting member
therefrom.
10. The holder of claim 2 wherein the commissure post constriction
comprises a ratchet assembly that maintains a space between the
valve abutment portion and the adjusting portion and holds the
commissure posts in the constricted position after the handle is
detached.
11. The holder of claim 10 wherein the ratchet assembly comprises
one or more ratchet members affixed to the valve abutment portion
that each engage a complementary opening in the adjusting
portion.
12. The holder of claim 2 wherein the commissure post constriction
comprises an upstanding leg on the valve abutment portion that
maintains a space between the valve abutment portion and the
adjusting portion and holds the commissure posts in the constricted
position after the handle is detached.
13. A method for retrofitting a holder for a tissue-type prosthetic
mitral heart valve attachable to a surgical delivery handle, the
heart valve having an inflow end and an outflow end and a flow axis
therebetween, the valve including an annular suture ring at the
inflow end and radially flexible commissure posts
circumferentially-spaced around the outflow end that support
occluding tissue surfaces of the valve, the holder having a
commissure post constriction mechanism releasably attached to the
sewing ring at the inflow end of the valve, the mechanism adapted
to constrict the valve commissure posts radially inward from a
relaxed position to a constricted position when actuated by the
delivery handle, the method including: providing a retaining
mechanism that retains the commissure post constriction mechanism
in the constricted position after the delivery handle is
removed.
14. The method of claim 13 wherein the step of providing includes
providing the retaining mechanism during the holder assembly
process so that the retaining mechanism is attached to and shipped
as a unit with the prosthetic valve.
15. The method of claim 13 wherein the step of providing includes
providing the retaining mechanism separately from the holder and
valve combination and the method includes coupling the retaining
mechanism to the holder at the time of surgical implantation of the
valve.
16. The method of claim 15 including packaging and selling the
retaining mechanism and delivery handle as a unit.
17. The method of claim 13 wherein the retaining mechanism
comprises an adapter that is interposed between and threadingly
engaged to the holder and the handle.
18. A kit of storage and handling clips and heart valve holders for
different diameter tissue-type prosthetic mitral heart valves, the
heart valves each having an inflow end and an outflow end and a
flow axis therebetween, each valve including an annular suture ring
at the inflow end and radially flexible commissure posts
circumferentially-spaced around the outflow end that support
occluding tissue surfaces of the valve, the kit comprising: a set
of holders each adapted to attach to the sewing ring at the inflow
end of a valve and having a generally planar portion including a
plurality of tangs radiating from a central body to cover a portion
of the suture ring, the tangs being radially dimensioned to
correspond to the diameter of the sewing ring; and each holder
including a plurality of peripheral notches in the planar portion;
and a plurality of identical storage and handling clips each having
a plurality of fingers for engaging the peripheral notches in any
one of the holders.
19. The kit of claim 18, wherein the planar portion of each holder
is generally triangular in shape with the tangs at the apices, and
a peripheral notch located adjacent each tang.
20. The kit of claim 18, wherein each clip comprises a disk portion
and a handle pivotally attached to one side thereof, with the
fingers extending generally axially from the other side
thereof.
21. The kit of claim 20, wherein there are three fingers in each
clip evenly disposed about the axis of the disk portion.
22. A method for replacing a heart valve, comprising the steps of:
providing a prosthetic tissue-type heart valve having an inflow end
and an outflow end and a flow axis therebetween and including a
suture ring affixed to a stent having commissure posts
circumferentially-spaced about the flow axis for supporting
occluding surfaces of the valve, the commissure posts being
cantilevered generally in the outflow direction; affixing a holder
to the inflow end of the valve; attaching a handle to the holder
and simultaneously constricting the commissure posts of the valve;
inserting the valve to the target annulus of the native heart valve
using the handle; removing the handle while maintaining the
commissure posts constricted; securing the valve to the annulus;
and detaching the holder from the valve.
23. The method of claim 22, wherein the holder comprises: a valve
abutment portion sized and shaped to abut the inflow end of the
valve; an adjusting portion coupled to the abutment portion
opposite the valve and able to move with respect to the abutment
portion; and one or more filaments attached to the adjusting
portion and coupled to the commissure posts that constrict the
commissure posts radially inwardly upon movement of the adjusting
portion with respect to the abutment portion, the method including
moving the adjusting portion away from the abutment portion when
attaching the handle to the holder so that the filaments are pulled
by the adjusting portion to cause the commissure posts to constrict
radially inward.
24. The method of claim 23 wherein the holder further includes an
adjusting member coupled to both the abutment portion and the
adjusting portion and adapted to transfer movement of the handle to
cause the adjusting portion to move with respect to the abutment
portion.
25. The method of claim 24, wherein the handle includes threads
that engage complementary threads on the adjusting member, and the
adjusting member includes threads that engage complementary threads
on the adjusting portion, wherein the frictional resistance to
rotation between the adjusting member and adjusting portion is
greater than the frictional resistance to rotation between the
handle and the adjusting member, the method including: fully
seating the handle into the adjustment member and advancing the
handle and adjustment member further to cause the adjusting portion
to move with respect to the abutment portion; and reversing
rotation of the handle to decouple the handle from the adjustment
member without reversing the adjustment member from engagement with
the adjusting portion.
26. The method of claim 23 wherein the abutment portion includes a
ratchet member that engages a complementary opening in the
adjusting portion to retain the valve in the constricted position
after the handle is removed, the method including ratcheting the
valve abutment portion and the adjusting portion apart.
27. The method of claim 23 wherein the abutment portion includes an
upstanding leg having a hook that couples the valve abutment
portion and the adjusting portion together and a stop member that
maintains a space between the valve abutment portion and the
adjusting portion to hold the commissure posts in the constricted
position after the handle is removed, the method including
displacing the valve abutment portion and the adjusting portion
apart until the stop member engages the adjusting portion.
Description
RELATED APPLICATION
[0001] The present application is a continuation-in-part of U.S.
application Ser. No. 09/626,570, filed Jul. 27, 2000.
FIELD OF THE INVENTION
[0002] The present invention relates generally to medical devices,
and more particularly to an apparatus for facilitating the
implantation of a bioprosthetic replacement heart valve, and
associated methodology.
BACKGROUND OF THE INVENTION
[0003] In mammalian 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 valves and have leaflets to
control the directional flow of blood through the heart. The valves
are each mounted in an annulus that comprises a dense fibrous ring
attached either directly or indirectly to the atrial or ventricular
muscle fibers. 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.
[0004] Two primary types of heart valve replacements or prostheses
are known. One is a mechanical-type heart valve that uses a ball
and cage arrangement or a pivoting mechanical closure to provide
unidirectional blood flow. The other is a tissue-type or
"bioprosthetic" valve which is constructed with natural-tissue
valve leaflets which function much like a natural human heart
valve's, imitating the natural action of the flexible heart valve
leaflets which form commissures to seal against each other to
ensure the one-way blood flow. In tissue valves, a whole xenograft
valve (e.g., porcine) or a plurality of xenograft leaflets (e.g.,
bovine pericardium) provide occluding surfaces that are mounted
within a surrounding stent structure. In both types of prosthetic
valves, a biocompatible cloth-covered sewing or suture ring is
provided on the valve body, for the mechanical type of prosthetic
valve, or on the inflow end of the stent for the tissue-type of
prosthetic valve.
[0005] In placing a tissue type prosthetic valve in the mitral
position, the commissure posts are on the blind side of the valve
and may become entangled with pre-installed sutures, and may damage
the annulus or tissue during delivery. The difficulty of the
delivery task is compounded if the surgery is through a
minimally-invasive access channel, a technique that is becoming
more common. The problem of entanglement is termed "suture
looping," and means that the suture that is used to attach or mount
the valve to the heart tissue is inadvertently wrapped around the
inside of one or more of the commissure post tips. If this occurs,
the looped suture may damage one of the tissue leaflets when
tightly tied down, or at least may interfere with valve operation
and prevent maximum coaptation of the valve leaflets, resulting in
a deficiency in the prosthetic mitral valve.
[0006] Some attempts have been made to overcome these problems in
current holders for prosthetic mitral valves. An example of such a
holder is U.S. Pat. No. 4,865,600, Carpentier, et al., incorporated
herein by reference. Carpentier provides a holder having a
constriction mechanism that constricts the commissure posts
inwardly prior to implantation. The Carpentier device provides an
elongate handle to both hold the valve/valve holder combination
during implantation, as well as to cause the commissure posts to
constrict inwardly. The valve is connected to the valve holder by
the manufacturer using one or more sutures, and the combination
shipped and stored as a unit. During the valve replacement
procedure, the surgeon connects the handle to the holder and locks
a locking nut to hold the commissure posts at a given constricted
position. The surgeon then attaches the sewing ring of the valve to
the native valve annulus with an array of sutures that has been
pre-embedded in the annulus and extended outside the body. The
valve is then advanced along the array of sutures to its desired
implantation position and the sutures tied off. When the holder is
cut free, the commissure posts are released to expand and the
holder may be removed using the handle. The inability to remove the
elongate handle while maintaining commissure constriction is a
detriment. The handle must be attached to the holder so that the
commissure posts remain in a constricted position during attachment
of the array of sutures to the sewing ring. This can be awkward for
manipulation of the valve/valve holder combination during this
time-constrained operation. Further, the relatively wide holder
periphery may interfere with the attachment step.
[0007] What is needed then is an improved tissue-type prosthetic
valve holder attachable to the inflow end of the valve that can
constrict the commissure posts with or without a handle being
attached, yet provides improved visibility and accessibility to the
surgeon during the valve attachment steps.
SUMMARY OF THE INVENTION
[0008] The present invention provides a holder for a tissue-type
prosthetic heart valve having an inflow end and an outflow end and
a flow axis therebetween. The valve includes an annular suture ring
at the inflow end attached to a stent having posts
circumferentially-spaced about the flow axis that support occluding
tissue surfaces of the valve. In this type of valve the posts are
cantilevered generally in the outflow direction.
[0009] The holder includes a valve abutment portion sized and
shaped to abut the suture ring at the inflow end of the valve. The
holder further includes a commissure post constriction mechanism
adapted to constrict the commissure posts radially inward from a
relaxed position to a constricted position when actuated by a
handle adapted to operatively connect to the commissure post
constriction mechanism. A retaining mechanism is also provided that
retains the commissure post constriction mechanism in the
constricted position after the handle is removed.
[0010] In one embodiment the commissure post constriction mechanism
comprises an adjusting portion and an adjusting member adapted to
adjust the distance between the adjusting portion and the valve
abutment portion and one or more filaments attached to the
adjusting portion and sutured through the end of the commissure
posts distal the adjusting portion. When the adjusting member is
operated to separate the adjusting portion from the valve abutment
portion the adjusting portion pulls the filaments, which in turn
urge the end of the commissure posts distal the adjusting portion
radially inwardly, to the constricted position.
[0011] The valve abutment portion may be of a planar shape, with
the adjusting portion of a substantially complementary planar shape
to the valve abutment portion. It is preferred that the planar
shape of the valve abutment portion be comprised of a plurality of
tangs radiating from a central body to each cover a portion of the
suture ring. In this manner a sufficient amount of the suture ring
is left exposed to allow for suturing the suture ring to the native
annulus.
[0012] Adjustment of the distance between the valve abutment
portion and the adjusting portion may be achieved by providing a
central threaded aperture in the adjusting portion and an adjusting
member that cooperates with this threaded aperture. In this
construction the end of the adjusting member proximal the valve
abutment portion abuts the valve abutment portion during operation.
When the adjusting member is advanced through the central aperture
of the adjusting portion it pushes the valve abutment portion and
the two portions separate.
[0013] A handle may be operatively connected to the adjusting
member to turn it by providing a handle that has an externally
threaded end portion and an adjusting member having a central
longitudinal threaded bore sized to receive the threaded end of the
handle. When the handle is introduced into the bore it is rotated
in a first direction and will seat in the threaded bore of the
adjusting member. Further rotation of the adjusting member
separates the adjusting portion from the valve abutment portion, as
recited above, and causes the commissure posts to constrict
inwardly.
[0014] In the prior art the handle would have to remain attached
during suturing of the suture ring to the host tissue to keep the
commissure posts in the constricted position. The holder with the
handle connected were removed by severing the filament(s) and
removing the holder, handle and filaments together.
[0015] In accordance with the present invention, the adjusting
member itself may be adapted to be the retaining mechanism.
Preferably, the adjusting member threads create a greater
frictional resistance with the threaded aperture of the adjusting
portion than that between the threaded end of the handle and the
threaded bore of the adjusting member. This frictional resistance
between the adjusting member and the central aperture allows the
handle to be further rotated in a second, opposite direction, and
the handle will detach or unscrew from the adjusting member without
moving the adjusting member, leaving the commissure posts in the
constricted position. The tug of the filaments themselves on the
adjusting portion when the commissure posts will cause the
adjusting member/central aperture thread interface to bind and so
may be used to achieve the requisite additional frictional
resistance required for allowing the handle to be unscrewed.
[0016] In alternative embodiments other mechanisms may be used in
accordance with the invention to act as the retaining mechanism.
For example, a ratchet assembly may be provided to lock the valve
attachment and adjusting portions apart, allowing the handle to be
removed while leaving the commissure posts in the constricted
position. A ratchet assembly may be comprised of a one or more
toothed members affixed to the valve abutment portion that each
engage a complementary notch, opening or, for example, a pawl
affixed to the adjusting portion. As the valve abutment portion and
the adjusting portion are separated by the adjusting member the
successive teeth of the toothed member engage the notch, opening or
pawl affixed to the adjusting portion, locking the two portions
apart.
[0017] The present invention further provides a method for
retrofitting a holder for a tissue-type prosthetic mitral heart
valve attachable to a surgical delivery handle. The heart valve is
of the type having an inflow end and an outflow end and a flow axis
therebetween, and includes an annular suture ring at the inflow end
and radially flexible commissure posts circumferentially-spaced
around the outflow end that support occluding tissue surfaces of
the valve. The holder has a commissure post constriction mechanism
releasably attached to the sewing ring at the inflow end of the
valve, the mechanism adapted to constrict the valve commissure
posts radially inward from a relaxed position to a constricted
position when actuated by the delivery handle. The method includes
providing a retaining mechanism that retains the commissure post
constriction mechanism in the constricted position after the
delivery handle is removed. The retaining mechanism may be provided
during the holder assembly process so that the retaining mechanism
is attached to and shipped as a unit with the prosthetic valve.
Alternatively, the retaining mechanism may be provided separately
from the holder and valve combination and the method includes
coupling the retaining mechanism to the holder at the time of
surgical implantation of the valve. The retaining mechanism and
delivery handle may be packaged and sold as a unit. The retaining
mechanism desirably comprises an adapter that is interposed between
and threadingly engaged to the holder and the handle.
[0018] Further in accordance with the invention a method for
replacing a heart valve is provided, comprising the steps of
removing an existing heart valve to leave an annulus of that heart
valve, attaching a holder of the invention to a prosthetic
tissue-type heart valve and constricting the commissure posts of
the prosthetic heart valve with a handle; inserting the valve
through the annulus of the heart valve; removing the handle while
leaving the commissure posts in the constricted position; suturing
the tissue-type heart valve to the heart annulus, and detaching the
holder from the prosthetic heart valve.
[0019] After suturing the heart valve to the annulus the surgeon
severs the filament, causing the posts of the stent to open to the
relaxed, operational position. The severing of the filament(s) also
releases the holder from the prosthetic heart valve, allowing it to
be removed.
[0020] A further understanding of the nature and advantages of the
present invention are set forth in the following description and
claims, particularly when considered in conjunction with the
accompanying drawings in which like parts bear like reference
numerals.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a perspective view of a heart valve holder of the
present invention assembled to the inflow side of a tissue-type
heart valve;
[0022] FIG. 2 is a perspective view of the holder/heart valve
assembly, showing an actuating and delivery handle attached to the
holder;
[0023] FIG. 3 is a perspective view of the holder/heart valve
assembly showing an adjusting portion retracted to cause inward
movement of the valve commissure posts;
[0024] FIG. 4 is a perspective view of the valve holder of the
present invention exploded from a tissue-type heart valve;
[0025] FIG. 5A is a plan view of an adjusting portion of the holder
of the present invention;
[0026] FIG. 5B is a sectional view through the adjusting portion of
the holder, take along line 5B-5B of FIG. 5A;
[0027] FIGS. 6A and 6B are partial sectional views of the holder of
the present invention attached to a heart valve wherein the
commissure posts of the valve are, respectively, relaxed and biased
inwardly;
[0028] FIGS. 7A-7C illustrates several steps in the implantation of
a tissue-type valve in the mitral position using the holder of the
present invention;
[0029] FIGS. 8A and 8B are partial sectional views of an
alternative holder of the present invention attached to a heart
valve wherein the commissure posts of the valve are, respectively,
relaxed and biased inwardly;
[0030] FIG. 9A is a perspective view of an exemplary storage and
handling clip that attaches to a holder of the present
invention;
[0031] FIGS. 9B-9F are various views of the handling clip of FIG.
9A;
[0032] FIG. 10 is a perspective view of the handling clip attached
to a holder and valve combination and placed within a storage
container shown in phantom;
[0033] FIG. 11A is a plan view of a heart valve holder of the prior
art attached to a heart valve and delivery handle during a step of
implantation into a valve annulus;
[0034] FIG. 11B is a plan view of a heart valve holder of the
present invention attached to a heart valve and delivery handle
during a step of implantation into a valve annulus;
[0035] FIG. 12A is an exploded perspective view of a valve, holder,
handle and adapter combination of the present invention;
[0036] FIGS. 12B-12C are perspective assembled views of the
combination of FIG. 12A showing two steps of operation thereof to
constrict commissures of the heart valve;
[0037] FIGS. 13A-13C are sectional views of the holder, handle, and
adapter combination of FIG. 12 showing several steps of
operation;
[0038] FIGS. 14A-14C are several views of an alternative adapter
for use with a valve holder of the present invention;
[0039] FIG. 15 is a partial elevational view of the interaction
between a pawl on the adapter of FIG. 14 and a raised feature on a
valve holder to ensure positive engagement therebetween; and
[0040] FIGS. 16A-16F are several sectional views of a portion of an
alternative holder of the present invention showing a further
apparatus for maintaining commissure constriction.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0041] The present invention provides an improved heart valve
holder for tissue-type prosthetic heart valves that facilitates
implantation and reduces the chance of suture entanglement. The
holder of the present invention is particularly useful for
prosthetic mitral heart valves having commissure posts on the
outflow side supporting flexible leaflets therebetween. The mitral
position is such that the outflow side (and commissure posts)
projects distally toward the left ventricle during implantation,
and thus the holder must be attached to the inflow (i.e.,
accessible) side of the valve. Delivery of the valve to the mitral
position involves sliding the valve down a plurality of sutures
that have been pre-installed around the annulus and then passed
through the valve sewing ring. The holder of the present invention
constricts the commissure posts radially inward and thus helps
prevent the posts from becoming entangled in the array of
pre-installed sutures. This benefit is thus particular to the
situation where the outflow side (and commissure posts) of the
heart valve extends distally during delivery, which is the case in
the mitral position. Nonetheless, the holder of the present
invention may prove useful for the implantation of heart valves in
other than the mitral position, and thus the invention may be
applicable thereto.
[0042] With reference now to FIGS. 1-3 an exemplary holder 20 of
the present invention is shown attached to a tissue-type heart
valve 22. The heart valve 22 includes an annular sewing ring 24 on
an inflow side, and a plurality of commissure posts 26 projecting
generally axially in the outflow direction. The holder 20 attaches
to the sewing ring 24 on the inflow side of the valve 22, which
also is the proximal (i.e., accessible) side during implantation.
That is, commissure posts 26 project distally toward the outflow
side of the valve 22.
[0043] FIGS. 2 and 3 illustrate a plurality of flexible leaflets 28
that are supported by and extend between the commissure posts 26.
The leaflets 28 provide the occluding surfaces of the valve 22, and
may be made of individual pieces of bovine pericardium, for
example. Alternatively, the leaflets 28 may be part of an entire
xenograft, or homograft. In the former instance, natural porcine
(pig) valves are particularly useful. Therefore it should be
understood that the leaflets 28 may be formed of a variety of
materials, none of which is limiting with respect to the present
invention. In addition, there are preferably three such leaflets 28
corresponding to three commissure posts 26.
[0044] Various constructions for the heart valve 22 are known,
which may include metallic or plastic stent elements, a silicone or
urethane insert for the sewing ring 24, biocompatible fabric (i.e.,
polyester) covering around one or more of the elements, etc. In a
preferred embodiment, the heart valve 22 includes an internal
metallic wireform (not shown) having an undulating shape with a
plurality of arcuate cusps connected by upstanding commissures. The
wireform commissures provide internal structure for the commissure
posts 26 of the valve, and are somewhat flexible so as to be able
to flex or cantilever inward. The holder 20 of the present
invention facilitates this flexing, though the invention is
generally directed toward causing the inward movement of the
commissure posts. Of course, other internal constructions of heart
valve 22 having movable commissure posts are available, with which
the holder 20 of the present invention may function equally as
well.
[0045] With reference still to FIGS. 1-3, and also FIG. 4, the
holder 20 of the present invention includes three relatively
movable elements. A plate-like valve abutment portion 40 lies
against the inflow side 32 of the sewing ring 24, and includes a
plurality of through holes 42 around its periphery. A plate-like
commissure adjusting portion 44 generally mirrors the shape of the
valve abutment portion 40, and also includes a plurality of
peripheral through holes 46. The adjusting portion 44 further
includes a centrally located and internally threaded boss 48 that
projects in a proximal direction from the otherwise generally
planar adjusting portion. Finally, an adjusting member 50 having
external threads 52 thereon is sized to mate with the internal
threads 54 of the boss 48
[0046] A plurality of filaments or sutures 60 are shown in FIGS.
1-3 partly extending between the tips 62 of the commissure posts
26. Because there are three commissure posts 26, there are at least
three lengths of sutures 60 extending therebetween in a triangular
configuration. Each length of suture 60 spans two of the commissure
posts 26, and threads proximally along the post and through the
sewing ring 24 to be attached to the holder 20. This is seen best
in the perspective view of FIG. 1. Specifically, each suture 60
passes through the holes 42 in the valve abutment portion 40 and
attaches to the adjusting portion 44. The specifies of the
attachment of each suture 60 will be explained below.
[0047] As mentioned, the abutment portion 40, adjusting portion 44,
and adjusting member 50 are relatively movable. That is, the
adjusting portion 50 is adapted to cause relative axial
displacement between the abutment portion 40 and the adjusting
portion 44. Because the abutment portion 40 remains against the
sewing ring 24, the adjusting portion 44 translates proximally away
from the abutment portion, and attached valve 22. This is seen in
FIG. 3. Because the sutures 60 attach to the adjusting portion 44,
they are also pulled in the proximal direction. Moreover, because
each suture 60 threads in a distal direction along and between two
of the commissure posts 26, proximal movement of the adjusting
portion 44 thus shortens the amount of each suture between the
commissure post tips 62. This shortening causes radially inward
movement of the tips 62, with the commissure posts 26 eventually
flexing inward from their structural point of attachment within the
valve 22 adjacent the sewing ring 24.
[0048] Now with reference to FIGS. 4 and 5A-5B, structural details
of the holder 20 of the present invention will be explained. As
mentioned above, the valve abutment portion 40 is generally
plate-like, and preferably includes a central, generally triangular
body 70 having three outwardly extending tangs 72 at the apices
thereof. Two through holes 42 are providing in each of the tangs
72, spaced apart along an imaginary circle centered in the
triangular body 70. Three upstanding pins or legs 74 having hooks
76 project from the proximal face of the body 70, preferably inward
and between each two tangs 72.
[0049] The adjusting portion 44, as best seen in FIG. 5A, also
includes a generally triangular plate-like body 80 that is sized
similar to the body 70 of the abutment portion 40. In this regard,
the adjusting portion 44 includes a plurality of channels 82 on the
face opposite the valve abutment portion 40 that received the hooks
76 of the upstanding legs 74 such that the plate-like bodies 70 and
80 can be juxtaposed against one another, though their separation
distance is limited. The hooks 76 thus effectively prevent
disengagement of the attaching portion 44 and the abutment portion
40 once the two are coupled together. The adjusting portion 44 also
includes three outwardly extending tangs 84 at the apices of the
triangular body 80. Like the abutment portion 40, two through holes
46 are provided on each of the tangs 84, and are spaced apart along
an imaginary circle centered in the body 80. Preferably, each
through hole 46 in the adjusting portion 44 aligns with a through
hole 42 in the valve abutment portion 40 when the holder 20 is
assembled.
[0050] Each tang 84 features a suture cutting guide 86 that
projects from the proximal face of the body 80. Each cutting guide
86 includes a central cutting recess 88 defined between a pair of
suture grooves 90. A cutting recess 88 extends generally radially,
while the suture grooves 90 are angled with respect thereto. The
depth of the suture grooves 90 is less than the depth of the
cutting recess 88, as seen in FIG. 5B, and thus a length of suture
60 can be strung between the grooves 90 so as to be suspended over
the cutting recess 88. As seen in FIG. 5A, the suture grooves 90
lead into both of the through holes 46 on either side of the
cutting guide 86, such that each suture bridges the cutting recess
88 and may be bent to be secured to or pass through one of the
through holes 46. The specific arrangement of the sutures 60 will
be more fully described below.
[0051] With reference still to FIG. 5A, the adjusting portion 44
further includes means for receiving clips on a removable transport
template that secures the holder 20 and heart valve 22 assembly
within a storage jar during transportation. Specifically, three
clip-receiving notches 100 are equidistantly spaced around the
periphery of the body 80. In the illustrated embodiment, the
notches 100 are disposed in a counter-clockwise direction adjacent
each of the tangs 84 (as seen from the proximal face). Each of the
notches 100 is spaced from the center of the body 80 a radial
distance 102, as indicated. As seen in the left of FIG. 5A,
progressively larger holders will have progressively larger tangs
84a, 84b, 84c so as to enable attachment to larger valve sizes.
Advantageously, the notch distance 102 remains constant for all the
various sizes of the holder 20 to provide a one-size-fits-all
template attachment means. That is, the same size of storage
template can be used for a set of different sizes of holders. This
arrangement also reduces the radial profile of the holders for
larger sized valves, as the dimension of the template notches with
respect to the overall perimeter is progressively reduced. This
size reduction further helps to prevent snags as the holder and
valve are delivered to the implantation site.
[0052] With reference again to the perspective views of FIGS. 1-3,
the arrangement of the discrete lengths of sutures 60 will now be
described. There are desirably three equal lengths of sutures 60,
each being secured at its free end to the adjusting portion 44.
Each length of suture 60 attaches to a first tang 84 of the
adjusting portion 44, passes through the aligned holes 46 and 42
(in a first tang of the abutment portion 40) and through the sewing
ring 24 to a first commissure post 26. From there, the suture 60
continues axially to the tip 62 of the post 26, and extends across
the outflow side of the valve 22 to the tip of a second commissure
post 26. The suture then passes proximally along the second
commissure post 26, again through sewing ring 24, and through
aligned holes 42 and 46 in second tangs 72, 84, respectively, of
the abutment portion 40 and adjusting portion 44. It should be
noted that each of the commissure posts 26 desirably has a fabric
covering, and the sutures 60 pass at least once through the fabric
covering at the tip 62 of each post.
[0053] At one of its free ends, the suture 60 passes between the
suture grooves 90 within one of the cutting grooves 86. Each length
of suture 60 is secured at both ends to different through holes 46
in the adjusting portion 44. Additionally, each two adjacent
lengths of suture 60 are secured to the same through hole 46. That
is, as seen in FIG. 1, two lengths of suture, 60a and 60b, are seen
extending along the closest commissure post 26 to the adjusting
portion 44. The first length 60a passes through the left through
hole 46b, over the cutting guide 86, and is secured to the right
through hole 46b. The second length 60b is secured to the right
through hole 46b and passes distally through sewing ring 24 to the
commissure post 26. The second length 60b does not cross the
cutting guide 86, but instead continues to the next commissure post
26 before extending proximally to the holder 20 and over its
associated cutting guide 86. In this manner, the lengths of sutures
60 can be completely disengaged from the valve 22 by simply making
three scalpel cuts in each of the three cutting guides 86.
[0054] The holder 20 of the present invention works in conjunction
with a delivery handle 110, as seen in FIGS. 2 and 4. As seen in
FIG. 4, the handle 110 includes a shaft 112 terminating in a distal
externally threaded rod 114. The adjusting member 50 is tubular and
includes internal threads 116 that are sized and configured to
receive the threaded rod 114. In addition, as mentioned above, the
adjusting member 50 is externally threaded so as to mate with
internal threads 54 on the boss 48 of the adjusting portion 44. By
coupling the adjusting member 50 to the boss 48, and then the
handle 110 to the adjusting member, the handle 110 connects to the
holder 20.
[0055] With reference to FIGS. 6A and 6B, use of the holder 20 to
radially constrict the commissure posts 26 is shown. Specifically,
FIG. 6A illustrates the holder 20 assembled to the heart valve 22
using the aforementioned lengths of suture 60. In its relaxed
configuration, the adjusting portion 44 lies flush against the
abutment portion 42. In this state, the adjusting member 50 is
threaded part way into the boss 48 such that a distal end contacts
the cavity 78 in the abutment portion 40, but can be further
advanced a distance A, as indicated. The handle 110 is shown also
part way engaged with the adjusting member 50, with the threaded
rod 114 still partly showing.
[0056] Now with reference to FIG. 6B, the handle 110 has been
completely screwed into the adjusting member 50, at which point
further rotation of handle 110 causes relative rotation between the
adjusting member 50 and the adjusting portion 44. In other words,
actuation of the handle 110 causes relative axial movement between
the adjusting member 50 and adjusting portion 44. This axial
movement is caused by advancement of the adjusting member 50 within
the boss 48, which causes the distal end of the adjusting member to
push against the abutment member 42. Because the adjusting member
50 is thus prevented from relative movement with respect to the
abutment member 42, further advancement of the adjusting member
causes the adjusting portion 44 to displace away from the abutment
portion 42, as indicated by the arrows 120. The adjusting portion
44 rides upward along the adjusting member 50 until it contacts a
proximal shoulder 122, with the resulting spacing B between the
adjusting portion 44 and abutment portion 42. Because of the
attachment of the lengths of suture 60 to the adjusting portion 44,
relative movement of the adjusting portion with respect to the
abutment portion 42 pulls each length of suture out of the valve
22. This, in turn, causes inward radial contraction of the
commissure posts 26, as indicated by the arrows 124.
[0057] In a preferred embodiment, the frictional resistance to
rotation between the adjusting member 50 and the adjusting portion
44 is greater than the frictional resistance to rotation between
the handle 110 and the adjusting member 50. Consequently, once the
commissure posts 26 have been radially constricted, as indicated in
FIG. 6B, the handle 110 can be removed (unscrewed) from within the
adjusting member 50 without causing relative rotation between the
adjusting member and the adjusting portion 44. Therefore, the
holder 20 maintains the radially constricted configuration of the
commissure posts 26. This inequality in frictional rotation can be
obtained in a number of ways. For example, the threaded rod 114 and
associated internal threads 116 of the adjusting member 50 have a
smaller diameter than the external threads 52 and associated
internal threads 54 of the boss 48. Simply by virtue of this size
relationship, and corresponding lower surface area in contact, less
resistance to rotation of the threaded connection between handle
110 and adjusting member 50 is obtained, all else being equal.
[0058] To insure the handle 110 can be removed without reversing
the adjusting member 50 with respect to the adjusting portion 44,
however, the materials are chosen to enhance the inequality in
frictional resistance, as mentioned above. That is, the materials
of the adjusting member 50 and adjusting portion 44 are chosen so
as to have a greater frictional resistance to relative sliding
movement than between the materials of the handle 110 and adjusting
member 50. In one embodiment, the adjusting member 50 and adjusting
portion 44 are made of the same or different polymers, while handle
110 is metal. Resistance to relative sliding movement between metal
and polymer is generally less than that between two polymers. In a
preferred embodiment, both the adjusting member 50 and adjusting
portion 44 are made of DELRIN, while handle 110 is made a
stainless-steel.
[0059] FIGS. 7A-7C illustrate several steps in the use of the valve
holder 20 the present mentioned. FIG. 7A illustrates a portion of
the heart H in cross-section, and specifically the left ventricle
LV into which the mitral annulus MA opens. A plurality of sutures
130 is shown pre-installed within the mitral annulus MA. In a
typical procedure, the sutures 130 are brought outside the body and
passed through the sewing ring 24 of the prosthetic valve 22. The
handle 110 attaches to the holder 20 of the present invention which
in turn is coupled to the valve 22 and operably engaged therewith
to radially constrict the commissure posts 26. During delivery of
the valve 22, this radial constriction of the commissure posts 26
helps prevent entangled of the posts with the array of
pre-installed sutures 130. Indeed, the access passageway to the
mitral annulus MA can be somewhat narrow and nonlinear, making the
possibility of suture entanglement problematic. However, radial
constriction of the commissure posts 26, in conjunction with the
barrier provided by the triangular suspension of sutures 60 between
the commissure posts, greatly reduces the chance of entanglement.
Moreover, the sutures 130 are entirely prevented by the triangular
suspension of sutures 60 from contacting the valve leaflets 28. Not
only does the radial constriction of the commissure posts 26 reduce
the chance of suture entanglement, but it also reduces the chance
of contacting one of the posts with the surrounding anatomy.
[0060] After all the sutures 130 have been pre-installed in the
mitral annulus MA and threaded through the sewing ring 24, the
valve 22 is lowered along the plurality of sutures 130 so that the
sewing ring 24 contacts and lies flush against the mitral annulus
MA, as seen in FIG. 7B. At this stage, the handle 110 is removed
from the holder 20 to facilitate tying off of each of the sutures
130 to secure the valve 22 against the mitral annulus MA. Again,
removal of the handle 110 is facilitated by the small frictional
resistance to rotation between the handle and holder 20, relative
to that between the actuating portions of the holder.
[0061] Finally, after securing the valve 22 within the mitral
annulus MA, each of the lengths of suture 60 is severed at the
cutting guides 86 to facilitate removal of the holder 20 from the
valve 22. FIG. 7C shows the severed free ends of the points of
suture 60 being pulled from within the valve 22. The holder 20 can
be removed using forceps, or handle 110 may be reattached to
facilitate the removal.
[0062] The present invention contemplates a number of different
structures that cause constriction of tissue-type valve commissure
posts using a handle, while also permitting removal of the handle
without releasing the commissure posts. FIGS. 8A and 8B illustrate
a second embodiment of a holder 150 that utilizes a ratchet
methodology. Without going into great detail concerning elements of
the holder 150 that are similar to those described above, the
alternative holder relies on one or more toothed or ratchet members
152 extending proximally from the abutment portion 40 to engage
complementary opening(s) in the adjusting portion 44. As the
adjusting portion 44 is displaced away from the abutment portion
42, ratchet members 152 retain that spacing, as indicated FIG. 8B.
In this way, the relative frictional rotation between handle 110,
adjusting portion 44, and adjusting member 50 is not important.
Indeed, the handle 110 and adjusting member 50 can be formed as
one-piece, rather than two as shown.
[0063] Now with reference to FIGS. 9A-9F and 10, use of a clip 160
as mentioned above to attach to holders 20 of the present invention
during shipping and storage of an attached valve is illustrated. As
illustrated, each clip 160 includes a generally planar C-shaped
disk portion 162 having a semi-circular handle 164 attached
thereto. The clip 160 is desirably molded of a suitable polymer,
with the handle 164 being formed by a semi-circular strip pivotable
with respect to the disk portion 162, with its ends attached by
living hinges 165 to a pair of upstanding bosses 166. In this
respect, the handle 164 lies generally parallel to the plane of the
disk portion 162 until pulled upward by the user.
[0064] Three fingers 168 depend downwardly from the disk portion
162 in the direction opposite the direction that the handle 164 may
be lifted. Each finger 168 includes an inwardly directed pawl 170
sized to couple with a holder 20 of the present invention. More
specifically, the three fingers 168 are circumferentially spaced
120.degree. around a common axis of the holder 20 and clip 160 so
as to engage the peripheral notches 100 on the adjusting portion 44
of the holder. As mentioned previously, the peripheral notches 100
for different sized valve holders are radially spaced a consistent
distance from the axis. Therefore, the same size clip 160 may be
used to couple to a plurality of holders for different sized
valves, thus reducing the inventory of clips required. After
coupling the clip 160 to the holder 20 (or adjusting member 50),
the handle 164 may be used to lower the valve 22 into a storage and
shipping container 172, as seen in FIG. 10. The periphery of the
disk portion 162 is sized to closely fit within the container 172,
and thus prevents the valve from movement in the container during
shipping.
[0065] The mitral valve holder 20 of the present invention provides
an additional advantage over earlier mitral valve holders, such as
the holder shown in U.S. Pat. No. 4,865,600 to Carpentier, et al.
Specifically, prior holders such as that shown in the Carpentier
patent were relatively wide in dimension so as to unnecessarily
interfere with attachment of the sutures to the valve and the valve
to the annulus.
[0066] The holder shown in the Carpentier patent, for example,
includes a disk-shaped outer holder plate to which a delivery
handle attaches. FIG. 11A illustrates a prior art holder 180
attached to the inflow end of a mitral valve during delivery of the
valve into position in an annulus 182. Various means are known for
obtaining access to the annulus 22, such as by using a pair of
retractors 184 as illustrated to pull surrounding tissue away from
surgical field. The outer disk-shaped plate 186 of the holder 180
may be seen occluding all of the mitral valve except for an outer
peripheral portion 188 of the sewing ring. A plurality of sutures
190 is shown extending out of the surgical field through the sewing
ring 188. These sutures 190 were previously embedded in the annulus
182, and threaded through the sewing ring 188 at a location outside
the patient. Though accomplished more conveniently outside the
patient, this pre-threading operation must be done after the
surgical site has been exposed, and thus time is of the essence. To
prevent perivalvular leakage, the array of sutures must be
relatively evenly circumferentially spaced and located along a
radial line, and this delicate operation may be impeded by the
relatively large sized holder body 186, and attendant reduced
sewing ring visibility.
[0067] After the pre-threading is complete, the surgeon connects a
handle 192 to the holder 180 and slides the valve and holder
combination down the array of sutures 190 into position in the
annulus 182. Because the disk-shaped outer plate 186 is so large,
as seen in FIG. 11A, the surgeon cannot see the leaflets from the
inflow side of the valve. Problems sometimes arise when the
forwardly directed commissures of the valve become entangled in one
or more of the sutures in the array. Such entanglement may be
visible through the inflow end of the valve, but as mentioned, that
view is blocked by the outer plate 186.
[0068] The present invention provides a holder permitting greater
visibility of the valve to help alleviate the aforementioned
problems associated with the time-critical processes of
pre-threading and then sliding the valve and holder into place.
FIG. 11B illustrates the holder 20 of the present invention
attached to the inflow end of a prosthetic valve having a
peripheral sewing ring 200. The holder 20 is as described above,
and like reference numerals for the various elements will be used.
Namely, the holder 20 has the approximately triangular-shaped body
80 of the adjusting portion 44 with three outwardly extending tangs
84 at the triangle apices. The tangs 84 feature a pair of through
holes 46 through which sutures (not shown for clarity) pass to
attach the adjusting portion 44 to the sewing ring 200 of the
valve.
[0069] The body 80 includes three generally linear sides 202
extending between the tangs 84 (although each side is interrupted
by the aforementioned clip-receiving notches 100). The sides 202
separate from and expose the surrounding portions of the sewing
ring 200. Indeed, the sides 202 expose the inner volume of the
valve, such that leaflets 204 of the valve can be seen from the
inflow end thereof. It will therefore be appreciated that the task
of pre-threading the array of sutures around the sewing ring 200 is
facilitated by the increased visibility of the sewing ring provided
by the triangular-shaped holder 20. More specifically, the surgeon
can pre-thread the array of sutures around the sewing ring 200 with
greater confidence that no sutures are placed too far radially
inward or outward, and that they are evenly circumferentially
spaced. At a minimum, the time needed to complete this task is
reduced. Furthermore, as the valve is introduced to the surgical
site along the array of sutures, the surgeon can inspect the
leaflets 204 from the inflow side thus enhancing early detection of
any suture looping or entanglement that will be visible from the
inflow side in the form of a deformed leaflet.
[0070] The present invention may provide an improved valve holder
as described above, or adapters as described below may be used to
retrofit valve holders of the prior art. In particular, FIGS.
12A-12C and 13A-13C illustrate several embodiments of an adapter
system of the present invention for use with a prior art valve
holder such as that shown in U.S. Pat. No. 4,865,600 to Carpentier,
et al. FIG. 12A shows a tissue-type mitral heart valve 210 having a
sewing ring 212, a plurality of upstanding commissures 214 with
distal tips 216, and a plurality of tissue-type leaflets 218
forming the occluding surfaces of the valve. A conventional holder
such as shown in Carpentier, et al. includes a lower plate 220
configured to abut and attach to the sewing ring 212, and an upper
plate 220 that works in conjunction with the lower plate 220 to
pull the commissure tips 216 of the valve 210 inward. The lower
plate 220 has a generally triangular body 224 having three
outwardly projecting tangs 226 each with a pair of through holes
228.
[0071] As seen in FIGS. 12B and 12C, three guide posts 230 on the
lower plate 220 and three locking posts 232 having outwardly
directed pawls 234 pass through and mate with apertures 236 evenly
circumferentially spaced around a disk-shaped body 238 of the upper
plate 222. The upper plate 222 further includes three outwardly
directed flanges 240 having through holes aligned with the through
holes 228 in the lower plate 220, and three cutting guides 242
projecting upward from the disk-shaped body 238. In addition, a
central internally threaded boss 244 is adapted to receive a
delivery handle of the prior art, such as shown at 246 having a
male threaded end 248.
[0072] The present invention provides an adapter 250 to be
interposed between the delivery handle 246 and internally threaded
boss 244, having a distal male threaded portion 252 and a proximal
female threaded portion 254. The distal male threaded portion 252
is configured to mate with the internally threaded boss 244, while
the proximal female threaded portion 254 receives the threaded end
248 of the handle 246.
[0073] Use of the adapter 250 is seen best in FIGS. 13A-13C, and
generally parallels the function of the adjusting member 50
previously described. As has been described previously, and in the
earlier patent to Carpentier, et al., the lower plate 220 and upper
plate 222 work in conjunction with the threaded delivery handle to
pull the commissure tips 216 inward. FIG. 12C illustrates the two
plates 220, 222 separated such that a plurality of sutures
connected to the upper plate 222 and passing into the valve and
between the commissures (seen at 260) are placed in tension causing
the commissure tips 216 to be pulled inward in the direction of the
arrows 262. FIGS. 13A-13C illustrate the holder in cross-section
and isolated from the valve to better illustrate this plate
separation. In contrast to the present invention, in the prior art
the delivery handle 246 had to remain threadingly engaged with the
upper plate 222 to maintain the plate separation.
[0074] In contrast, the adapter 250 of the present invention
permits the delivery handle 246 to be removed while maintaining
plate separation. FIG. 13A shows the adapter 250 threadingly
attached to the delivery handle 246. The combination handle 246 and
adapter 250 is then coupled to the upstanding boss 244 on the upper
plate 222 and advanced so that a distal end 264 on the adapter
contacts a central pin 266 on the lower plate 220. Further
advancement of the handle 246 and adapter 250 combination causes
separation between the lower and upper plates 220, 222. The
separation may be limited by contact between the enlarged proximal
portion 254 with the upstanding boss 244, or by engagement of each
of the three pawls 234 with corresponding features on the upper
plate 222, both shown in FIG. 13B. Subsequently, the delivery
handle 246 may be reversed from engagement with the adapter 250 and
removed from the surgical site, as seen in FIGS. 12C and 13C. The
adapter 250 remains in the position shown in FIG. 13C, maintaining
the separation between the lower and upper plates 220, 222, but not
interfering with the implantation operation.
[0075] There are number of ways to ensure that the handle 246 may
be retracted from engagement with the adapter 250 while leaving the
adapter in place. For example, and as mentioned above in
conjunction with the earlier embodiment, the coefficient of
friction between the materials of the engaging threads can be such
that the handle 246 can be easily removed. For example, the upper
plate 222 is typically molded from a polymer such as Delrin, and
the adapter 250 can be formed of a similar material to produce a
relatively high coefficient of friction between the respective
threads. At the same time, the handle 246 may be made of
stainless-steel, for example, which produces a lower coefficient
friction between the male threads 248 and the female threads of the
proximal adapter portion 254. If the adapter 250 is made a suitable
polymer, such as the material of the holder, it may be coupled to
the holder prior to packaging, shipping and storage. Many
tissue-type heart valves are stored in a preservative solution,
such as glutaraldehyde, and material of the holder and adapter 250
must be able to withstand long periods of immersion in such
solutions.
[0076] Alternatively, the adapter 250 may also be made of
stainless-steel, with the relative coefficients of friction being
favorable for reversal and removal of the handle 246. In this
configuration, the adapter 250 may be sold as a separate article to
be coupled with existing delivery handles to retrofit prior art
systems. In this manner, both the handle 246 and adapter 250 are
able to withstand the high temperatures of steam sterilization, and
may be reused.
[0077] Another way to ensure that the adapter 250 remains coupled
to the upper plate 222 while the handle 246 can be removed is to
provide slightly dissimilar thread patterns on the adapter and
female threads of the upper plate boss 244. As the handle 246 and
adapter 250 are threadingly engaged to the boss 244, the dissimilar
threads tend to bind and lock the adapter to the upper plate 222.
Consequently, the handle 246 can be easily reversed and de-coupled
from the adapter 250.
[0078] A still further method of preventing the coupling of the
adapter 250 and upper plate 222, while permitting removal of the
handle 246, is to provide a groove, raise rib, or similar expedient
on the adapter that engages with a mating feature on the upper
plate. For example, although not shown, the lower surface of the
proximal portion 254 may include a raised radially-directed rib
that mates with a groove or similar rib on the upper surface of the
boss 244. After the two parts 250, 222 are threadingly engaged, as
seen in FIG. 13B, the raised ribs interfere and prevent
disengagement, at least to the extent of withstanding the torque
applied upon removal of the handle 246 from engagement with the
adapter 250.
[0079] A still further configuration in accordance with the present
invention is illustrated FIGS. 14A-14C and 15. In this embodiment,
an adapter 280 is provided that includes a distal male threaded
portion 282, a proximal female threaded portion 284 and a generally
disk-shaped flange 286 interposed therebetween. The flange 286
includes at least one distally-directed tooth or pawl 288 close to
a peripheral edge. The adapter 280 is shown in FIG. 14C in an
orientation in which it may be coupled with a holder located below,
and a handle located above. In particular, the handle will couple
to the female threaded portion 284, while the male threaded portion
282 couples with a boss on the holder and causes the aforementioned
inward movement of the associated valve commissures.
[0080] FIG. 15 is a partial cutaway that shows engagement of the
pawl 288 with an upstanding feature on the valve holder 290, such
as a cutting guide 292. That is, rotation of the adapter 280 in the
direction of arrow 294 causes the pawl 288 to cam up and over the
cutting guide 292. Because of the shape of the pawl 288, the
adapter 280 cannot be rotated in the opposite direction. Thus, the
adapter 280 is maintained in its threading engagement with the
holder, which maintains the aforementioned inward bias of the valve
commissures, and permits removal of the handle. The positive
engagement of the pawl 288 with the cutting guide 292 ensures that
the adapter 280 cannot be removed from the holder once coupled
thereto. The illustrated adapter 280 is representative of one type
of adapter that can be used to retrofit existing valve holders.
Specifically, the adapter 280 can be sold in combination with the
valve holder, and be stored with the valve, or can be sold as a
separate item to be coupled with handle at the time of surgery.
[0081] FIGS. 16A-16F illustrate portions of an alternative holder
of the present invention having an alternative structure for
maintaining valve commissure constriction. A segment of a valve
abutment portion 300 is shown interacting with a segment of an
adjusting portion 302. The abutment portion 300 and adjusting
portion 302 may in other respects be identical to those illustrated
in FIGS. 4 and 5A-5B. Indeed, the abutment portion 300 includes at
least one upstanding leg 304 having a hook 306, as described
previously. In addition to the leg 304, an upstanding gap retainer
308 is provided, preferably adjacent thereto. The gap retainer 308
includes a stop member 310 having a lower angled surface 312. In
preferred embodiment, there are two or more, preferably three,
pairs of legs 304 and gap retainers 308. Furthermore, although the
leg 304 and gap retainer 308 are illustrated as separate elements,
they may be incorporated into a single upstanding element or
leg.
[0082] FIGS. 16A-16C illustrate a process of assembling the holder
by insertion of the leg 304 and gap retainer 308 through an
aperture 314 provided in the adjusting portion 302. As seen, the
leg 304 and gap retainer 308 are cantilevered and spaced apart so
that they may be biased toward one another and fit through the
aperture 314. Both the hook 306 and stop member 310 are axially
aligned so as to normally interfere with respective sides of the
aperture 314, and the leg 304 and gap retainer 308 must be bent to
permit passage through the aperture 314.
[0083] FIGS. 16D-16F illustrate operation of the holder. FIGS. 16D
shows the relative positioning of the valve abutment portion 300
and adjusting portion 302 during storage and shipping of the holder
and attached valve. Prior to delivery of the valve along a surgical
pathway, the valve abutment portion 300 and adjusting portion 302
are separated so as to constrict the valve commissures, as was
described previously. This separation is desirably accomplished
using a handle with or without an adapter. As the adjusting portion
302 moves relatively away from the abutment portion 300, depicted
in FIGS. 16E, the aperture 314 contacts the lower angled surface
312 of the stop member 310 and cams the cantilevered gap retainer
308 inward. Subsequently, the gap retainer 308 springs upright to
its relaxed position, as seen in FIGS. 16F, such that the stop
member 310 again interferes with and contacts the face of the
adjusting portion 302 and prevents it from moving back toward the
abutment portion 300. In this manner, a simple and reliable
mechanism for maintaining separation of the holder elements
provides a positive stop and insurance against inadvertent
commissure expansion.
[0084] It will be appreciated that the invention has been described
hereabove with reference to certain examples or preferred
embodiments as shown in the drawings. Various additions, deletions,
changes and alterations may be made to the above-described
embodiments and examples without departing from the intended spirit
and scope of this invention. Accordingly, it is intended that all
such additions, deletions, changes and alterations be included
within the scope of the following claims.
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