U.S. patent application number 10/840464 was filed with the patent office on 2004-10-14 for heart valve and fixture assembly.
Invention is credited to Capps, Mark J., Eberhardt, Carol E., Hessler, Tom, Kalam, Faisal, Millwee, Billie, Shay, Janice, Toomes, Christopher G..
Application Number | 20040204758 10/840464 |
Document ID | / |
Family ID | 29248662 |
Filed Date | 2004-10-14 |
United States Patent
Application |
20040204758 |
Kind Code |
A1 |
Eberhardt, Carol E. ; et
al. |
October 14, 2004 |
Heart valve and fixture assembly
Abstract
A replacement heart valve and fixture assembly for limiting
longitudinal stretch during fixation of a harvested aortic root
including valve leaflets. The assembly includes an inflow plug
inserted into the inflow section of the aortic root and having an
apertured tube or cannula extending through the valve leaflets to
an outflow plug inserted into the outflow section of the aortic
root. Apertures in the tube are located on either side of the valve
leaflets and the tube is coupled to a fluid inlet, preferably
located on the outflow plug. The outflow plug is slidable relative
to the tube and is provided with an engagement mechanism such as a
setscrew for fixing the location of the outflow plug relative to
the tube and the inflow plug.
Inventors: |
Eberhardt, Carol E.;
(Fullerton, CA) ; Toomes, Christopher G.; (Orange,
CA) ; Capps, Mark J.; (Mission Viejo, CA) ;
Millwee, Billie; (Fullerton, CA) ; Shay, Janice;
(Lake Forest, CA) ; Hessler, Tom; (Tustin, CA)
; Kalam, Faisal; (Anaheim, CA) |
Correspondence
Address: |
MEDTRONIC, INC.
710 MEDTRONIC PARKWAY NE
MS-LC340
MINNEAPOLIS
MN
55432-5604
US
|
Family ID: |
29248662 |
Appl. No.: |
10/840464 |
Filed: |
May 6, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10840464 |
May 6, 2004 |
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10131979 |
Apr 25, 2002 |
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6761735 |
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Current U.S.
Class: |
623/2.15 ;
623/918 |
Current CPC
Class: |
Y10S 623/901 20130101;
Y10S 623/915 20130101; A61F 2/2415 20130101 |
Class at
Publication: |
623/002.15 ;
623/918 |
International
Class: |
A61F 002/24 |
Claims
In conjunction with the above specification, we claim:
1. A replacement heart valve and fixture assembly comprising: a
harvested aortic root having an inflow section, an outflow section
and valve leaflets; a first plug in sealing relation to the inflow
section; a second plug in sealing relation to the outflow section;
a tube extending through the aortic root and secured to the first
and second plugs such that the tube passes through the
leaflets.
2. An assembly according to claim 1 wherein the tube is secured to
the first plug by means of a setscrew.
3. An assembly according to claim 1 wherein the tube is slideably
secured to the first plug.
4. An assembly according to claim 1 further comprising a fluid
inlet coupled to the tube.
5. An assembly according to claim 1 wherein the first plug
comprises an engagement mechanism operable to fix the tube in
position relative to the first plug.
6. An assembly according to claim 4 wherein the fluid coupling is
located on the first plug and wherein the tube extends into the
fluid inlet.
7. An assembly according to any of claims 1 to 6 wherein the tube
includes a plurality of apertures therethrough.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of Ser. No. 10/131,979,
HEART VALVE FIXATION PROCESS AND APPARATUS, filed Apr. 25,
2002.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to the production of tissue
heart valves generally and more particularly to fixtures for use in
conjunction with fixation of valve tissue.
[0003] Tissue heart valves may be fabricated by harvesting a
mammalian aortic root including the aortic valve and thereafter
fixing the harvested aortic root to crosslink the tissue.
Thereafter, the aortic root may be trimmed and employed as heart
valve for implantation in human beings. The valve may be mounted to
a stent or frame, for example as disclosed in U.S. Pat. No.
5,824,069, issued to Lemole, U.S. Pat. No. 4,816,029, issued to
Penney, et al., U.S. Pat. No. 5,716,401, issued to Eberhardt, et
al. or U.S. Pat. No. RE 30,912, issued to Hancock. Alternatively,
the valve may be implanted without an associated stent, as
described in U.S. Pat. No. 5,336,258, issued to Quintero, et al or
U.S. Pat. No. 6,074,419, issued to Healy, et al.
[0004] U.S. Pat. No. 5,824,060 issued to Christie, et al. and
incorporated herein by reference in its entirety describes a
process for heart valve fixation, in which the harvested aortic
root is subjected to a fixative fluid to provide a first
differential fluid pressure across the tubular wall of the outflow
section of the aortic root and a second differential fluid pressure
across the valve leaflets. As disclosed, the inflow and outflow
sections of the aortic root are coupled to fluid couplings that are
in turn coupled to sources of fixative fluid under pressure. The
entire assembly is also placed in fixative fluid during the
fixation process.
[0005] U.S. Pat. No. 5,830,239 issued to Toomes and incorporated
herein by reference in its entirety describes an improvement to the
process of the '060 patent, in which only the outflow section of
the aortic root is mounted to a fluid coupling and the inflow
section of the root is blocked by a plug. The plug is provided with
a tube or cannula having an inlet portion extending through the
valve leaflets and an outlet opening located in the inflow section
of the aortic root, allowing fixative fluid to flow through the
valve so that fluid may be applied to both sides of the valve and
to the inflow and outflow sections of the aortic root. The fluid
coupling is coupled to a source of fixative and the entire assembly
is placed in fixative during the fixation process. The process
disclosed in the '239 patent substantially simplifies the fixturing
process as compared to the '060 patent.
SUMMARY OF THE INVENTION
[0006] The present invention is an improvement to the process
described in the '239 patent, providing a way to control axial
stretch of the aortic root during the fixation process. Because the
stretch of the aortic root is controlled, the fixturing system and
process of the present invention is intended to produce an
increased yield as compared to the process in the '239 patent.
[0007] The fixturing system of the present invention resembles that
as described in the '239 patent, in that only a single fluid
coupling is employed, preferably part of an outflow plug coupled to
the outflow section of the aortic root, and in that the inflow
section of the aortic root is blocked by an inflow plug. However,
in the present invention, the cannula or tube extending from the
inflow plug extends through the valve all the way to the outflow
plug. The tube smoothly slides into the outflow plug, allowing for
adjustment of the relative positions of the inflow and outflow
plug. The outflow plug preferably has a setscrew or other mechanism
associated therewith for fixing the location of the inflow plug
relative to the ouflow plug. The tube is provided with a series of
holes extending along of the tube and arranged to be located on
both sides of the valve leaflets, so that a zero pressure
differential across the leaflets can be achieved during
fixation.
[0008] In use, the outflow section of the aortic root is preferably
first coupled to the fluid coupling, which in the preferred
embodiment of the invention is part of an outflow plug, around
which the outflow section of the aortic root is mounted. The fluid
coupling is then coupled to a source of compressed air to close the
valve leaflets and a contour ring is placed around the inflow
section of the aortic root. The aortic tissue at the end of the
inflow section of the aortic root is then folded back over the
contour ring and a length of plastic tubing is slid over the tissue
and contour ring and is maintained in place, for example, by means
of a cable tie. Other mechanisms for restraining the outflow
section of the aortic root during fixation may be substituted for
the contour ring or the contour ring might, in some embodiments, be
attached without prior application of pressure to close the valve
leaflets.
[0009] The apertured tube or cannula and the attached inflow plug
are then inserted into the aortic root with the tube passing
through the valve leaflets and engaging the fluid coupling. The
inflow plug attached to the tube is located within the plastic
tubing and attached to it by means of cable ties or the like,
compressing the tubing around the inflow plug. The fluid coupling
is then again attached to a source of compressed air, which is used
to inflate the aortic root to a desired pressure and the setscrew
is employed to fix the outflow plug to the tube, correspondingly
stabilizing the relative location of the inflow and outflow
sections of the aortic root and preventing excessive longitudinal
stressing during fixation. The assembly is then moved to a fixative
bath where the outflow plug is coupled to a source of fixative
under pressure, and the assembly is placed into the fixative bath
during the fixation process. On completion of fixation, the aortic
root is removed and trimmed and may thereafter be mounted to an
associated heart valve stent.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 shows a cross section of a harvested porcine aortic
root mounted to the outflow plug of the present invention.
[0011] FIG. 2 shows the aortic root and outflow plug of FIG. 1
inverted so that the outflow plug may be coupled to a source of
compressed air to close the valve leaflets and allow placement of
the contour ring.
[0012] FIG. 3 shows the assembly of FIG. 2 after addition of a
length of plastic tubing, mounted around the contour ring and
inflow section of the aortic root.
[0013] FIG. 4 shows the assembly of FIG. 3 to which the inflow plug
and associated tube have been mounted.
[0014] FIG. 5 illustrates the assembly of FIG. 4 mounted in a
fixative bath.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] FIG. 1 is a cut away view illustrating a harvested porcine
aortic root 10 mounted to outflow plug 20. The aortic root includes
the leaflets 12 of the aortic valve, an outflow section 14 and an
inflow section 16. In the fixation method of the present invention,
the outflow section 14 is first mounted to the outflow plug 20 by
inserting the plug 20 into the outflow section 14 and compressing
the outflow section around the plug 20 by means of a cable tie 22
or the like.
[0016] The outflow plug 20 is provided with a fluid coupling 24,
including a fluid inlet lumen 26. Also included in outflow plug 20
are a threaded setscrew 28 and an o-ring 30. As discussed above,
the setscrew functions to lock the position of the outflow plug 20
relative to the tube or cannula and the attached inflow plug (not
illustrated). As such, the screw 28 is sized so that when its end
is engaged with the tube extending through the input passage 26,
O-ring 30 will be compressed to provide a fluid seal to prevent
leakage of fixative or air, along the threads of the screw 28.
[0017] FIG. 2 is a cut away view of the assembly of FIG. 1,
inverted to allow attachment to a source of compressed air via
fluid coupling 24. Other numbered items correspond to identically
numbered items in FIG. 1. The process according to the present
invention continues from the previous steps illustrated in FIG. 1
as follows. Fluid coupling 24 is coupled to a source of compressed
air at approximately two inches H.sub.2O of pressure. This serves
to close the leaflets 12 of the aortic valve, maintaining the
aortic root in a position in which the leaflets properly coapt.
Contour ring 32 is then slid over the inflow section 16 of the
aortic root 10, and the end of the inflow section is folded over
the contour ring 32. As described in the above cited '239 et al
patent, contour ring 32 serves to maintain the configuration of the
aortic root in the vicinity of the leaflet bases in an appropriate
configuration to assure valve coaption after fixation.
[0018] FIG. 3 illustrates the apparatus in FIG. 2, during the next
steps of the process according to the present invention. All
numbered items correspond to identically numbered items if FIG. 2.
After placement of the contour ring 32 around the inflow section 16
of the aortic root 10, a plastic tube 36 which can be fabricated,
for example, of silicone rubber is slid over the inflow section 16
and the contour ring 32 and is maintained in place by means of a
cable tie 34 or the like as illustrated. Silicone tube 36 will
serve to mount the inflow plug and associated tube, as discussed
below.
[0019] FIG. 4 illustrates the next step in the process according to
the invention, and includes the apparatus illustrated in FIG. 3
above. Numbered components correspond to identically numbered
components in FIG. 3 above.
[0020] Inflow plug 38 and associated tube 42 have been added to the
assembly of FIG. 3 above. The inflow plug 38 is sealed within
plastic tube 36 by means of one or more cable ties 40 or the like.
The plug thus effectively seals the inflow section of the aortic
root 10 against leakage. Apertured tube 42, mounted to inflow plug
38, extends through the aortic valve leaflets 12, and outward
through the fluid inlet lumen 26 in fluid coupling 24. Fluid inlet
24 is then coupled to a source of compressed air, preferably at
about 10 plus or minus 1 inches H.sub.2O. The pressurized air is
delivered to the interior of the aortic root in both the outflow
and inflow sections, primarily by means of holes 44 in tube 42. The
air pressure serves to inflate the aortic root to a desired, but
limited degree. During inflation, tube 42 is free to slide within
the internal lumen 26 of fluid inlet 24 to an optimal position for
fix ation. The inlet and outflow plugs 38, 20 and the attached
aortic root 10 are now in the desired configuration for the
fixation process.
[0021] After inflation of the aortic root, setscrew 28 is tightened
against tube 42 to lock it in position relative to the outflow plug
20 and fluid coupling 24. 0-ring 30 is concurrently compressed to
seal against fluid losses during fixation that might otherwise
occur around the threads of screw 28. The assembly is now ready to
be placed in the fixative bath and attached to a source of
fixative. It has been determined that allowing inflation of the
valve to determine the spacing of the inflow and outflow plugs
provides for a procedure which produces preserved porcine aortic
roots without undue longitudinal stretching, improving the yield of
the process.
[0022] FIG. 5 is a cut away view illustrating the fixation portion
of the process according to the present invention. In this view,
the assembly illustrated in FIG. 4 is inverted and placed in a
fixative bath 50, containing fixative 52 which may be, for example,
a 0.2% aqueous solution of gluteraldehyde. Other fluid fixatives
(liquid or gaseous), as disclosed in U.S. Pat. No. 5,880,242,
issued to Hu, et al., U.S. Pat. No. 5,733,339, issued to Girardot,
et al., U.S. Pat. No. 5,376,110, issued to Tu, et al., U.S. Pat.
No. 5,447,536, issued to Girardot, et al., U.S. Pat. No. 5,931,868,
issued to Gross, et al. or U.S. Pat. No. 4,880,603, issued to
Jaffe, all incorporated herein by reference in their entireties,
may also be employed in conjunction with the method of the present
invention. The fluid inlet 24 is coupled to a source of fixative
under pressure, for example, the same as fixative 52, but under
pressure. The fixative is delivered to the interior of the aortic
root via the holes 44 in tube 42. The assembly remains in the
fixative bath with pressurized fixative applied via the fluid
coupling 24 until fixation is complete. Fixation times will vary as
a function of the pressures and fixatives employed.
Anti-calcification treatments, for example using alpha-aminooleic
acid as described in U.S. Pat. No. 4,976,733, issued to Girardot,
et al. and incorporated herein by reference in its entirety, may
also be employed.
[0023] In a preferred embodiment of the invention using a porcine
aortic root, the pressure the fixative solution provided via the
fluid coupling 24 is adjusted to provide a pressure drop across the
walls of the aortic root of about 40 mm Hg. However, as described
in the '060 and '239 patents cited above, the pressure drop may be
substantially higher or lower, e.g. 20-120 mm Hg. The desired
pressure drop may also vary as a function of the species from which
the aortic root was harvested. Because the fluid is delivered at
equal pressure to both sides of the aortic valve leaflets 24, there
is effectively a zero pressure drop across the valve leaflets. The
pressure drop across the walls of the aortic root is determined by
the difference between the inlet pressure at fluid inlet 24 and the
pressure of the fixative solution 52 in the fixative bath 50. While
FIG. 5 illustrates a single fixture and aortic root assembly
located in a fixation tank, it should be understood that in
commercial embodiments of the present invention, multiple such
assemblies will be coupled to piccolo tubes as described in the
above-cited '239 patent, and simultaneously fixed within a larger
fixative bath.
[0024] It should be noted that while the disclosed embodiment
employs a setscrew to fix the tube to the fluid coupling, other
mechanisms such as clamps, collets, pins, cams, detents or other
devices may be substituted. Further, while in the embodiment as
described, the pressure differential across the walls of the aortic
root is kept generally constant during the fixation process,
pulsatile or varying pressure may in some cases be employed. In
addition, while in the preferred embodiment, the fluid coupling is
mounted to the inflow plug and extends through the outflow plug, it
is possible that a reversal of these elements so that the fluid
coupling is associated with the. Finally, while inflation of the
aortic root to establish the desired spacing of the inflow and
outflow plugs, it is believed that the invention might still be
usefully practiced in embodiments in which some other method, e.g.
mechanically stretching the root to a desired length or tension, is
used to determine the desired spacing. As such, the above-disclosed
embodiment should be considered as exemplary, rather than limiting
in conjunction with the claims that follow.
* * * * *