Title:
BICUSPID FASCIA LATA VALVE
United States Patent 3739402


Abstract:
A graft-support for homograft and heterograft tissue valve implantation comprising a ring base, two struts extending from one side of the ring base and generally parallel to its axis, and a fabric layer covering the entire surface of the ring and struts. The fabric layer has a thickened portion at the apex of each strut, a second thickened portion along the top edge of the ring and a third thickened portion extending circumferentially of the ring. These thickened portions provide means for suturing the graft-support to the valve tissue and to the host heart, respectively. In one very advantageous embodiment, the ring is generally oblong in shape having a long diameter and a short diameter and the struts are disposed opposite to each other, one at each end of the oblong ring, i.e., at each end of the long diameter thereof or on a line parallel thereto. In effecting the transplantation, animal tissue, such as fascia lata derived from the patient, is wrapped around the upstanding struts and joined at the ends by suturing to form a closed ring of tissue, and forming also two cusps thereof supported by the struts. Each cusp is then sutured at its base to the covering at the top surface of the ring and along the sides of the struts, and a pledget of the fabric or suture is affixed around the top of the strut, the fabric thereover and the tissue to ensure coaptation of the cusps. The tissue, especially fascia lata from the patient, can also be extended to cover the side of the third thickened portion, or sewing ring, which is exposed to the ventricle so that, when the valve is emplaced, the entire ventricular surface is covered with autologous tissue. The device is then placed in the mitral valve position with struts extending into the ventricle and the host heart is sutured to the peripheral thickened flange, i.e., the third thickened portion.



Inventors:
Cooley, Denton A. (Houston, TX)
Liotta, Domingo S. (Houston, TX)
Kahn, Paul (San Francisco, CA)
Application Number:
05/081064
Publication Date:
06/19/1973
Filing Date:
10/15/1970
Assignee:
CUTTER LABOR INC,US
Primary Class:
Other Classes:
623/900
International Classes:
A61F2/24; (IPC1-7): A61F1/22
Field of Search:
3/1,DIG.3 128
View Patent Images:
US Patent References:
3570014N/A1971-03-16Hancock
3548418GRAFT VALVE TRANSPLANTATION FOR HUMAN HEARTS AND GRAFT-SUPPORT RING THEREFOR1970-12-22Angell et al.
3451067HEART VALVE1969-06-24Jordan
3263239Aorta valve with expansible suturing ring1966-08-02Edwards et al.



Other References:

"Surgery for Aortic Valve: Prosthesis and Heterograft" by M. J. Levy et al., Surgery, Vol. 66, No. 2, pp. 313-318, August 1969. .
"Surgitool Aortic Valve Prosthesis" (Advertisement by Surgitool), The Journal of Thoracic & Cardiovascular Surgery, Vol. 58, No. 3, September 1969. .
"The Homograft Prosthesis" by N. E. Shumway et al., Prosthetic Heart Valves by L. A. Brewer, Editor-in-Chief, Charles C. Thomas, Publisher, Springfield, Illinois, pages 769-777, 1968. .
"Heart-Valve Replacement With Autologous Fascia Lata" by M. I. Ionescoll et al., The Lancet, Vol. 2, Aug. 16, 1969, pages 335-338. .
"Technique of Mitral Valve Replacement with Autologous Fascia Lata" by J. B. Flege et al., Journal of Thoracic & Cardiovascular Surgery, Vol. 54, No. 2, August 1967, pp. 222-226. .
"Prosthetic And Fascia Lata Valves: Hydrodynamics and Clinical Results" by D. Liotta et al., Trans. Amer. Soc. Artif. Int. Organs, Vol. XVI, April 1970, pages 244-251..
Primary Examiner:
Gaudet, Richard A.
Assistant Examiner:
Frinks, Ronald L.
Claims:
We claim

1. A graft-support ring for a bicuspid valve for valve replacement in a damaged heart, including in combination

2. A graft-support ring as in claim 1 wherein said prongs extend from said ring approximately at the opposite ends of said major axis.

3. A graft-support ring as in claim 1 wherein said prongs are inclined outwardly at a small angle with respect to a line perpendicular to the plane of said area.

4. A graft-support ring for a bicuspid valve for use with autologous, homologous, or heterologous tissue, including in combination

5. A graft-support ring as in claim 4 wherein said metal ring and struts are machined from one piece of titanium metal.

6. A graft-support ring as in claim 4 wherein said flange extends at an angle of from about 30° to about 60° to said central axis.

7. A graft-support ring as in claim 4 wherein said struts are inclined outwardly at a small angle with respect to the axis of the ring.

8. A graft-support ring as in claim 4 wherein one of said struts is disposed on said metal ring at each end of said long diameter.

9. A bicuspid fascia lata valve for insertion into a ventricle valve opening of a heart and providing ventricle-exposed surfaces, including in combination,

10. A fascia lata valve as in claim 9 wherein said metal frame is machined from one piece of titanium.

11. A fascia lata valve as in claim 9 wherein said fascia lata is autologous tissue.

12. A fascia lata valve as in claim 9 wherein said struts are disposed on a plane parallel to and offset from said center line.

Description:
BACKGROUND OF THE INVENTION

This invention relates to a graft-support for valve transplantation into the human heart, and particularly it concerns a bicuspid device. The invention also concerns a method of effecting valve replacement, especially with the use of a homograft or autologous graft.

Synthesized and replacement tissue heart valves have been hitherto known to the art, and various types of such valves have been developed, both homograft and heterograft. It has been recognized that a tissue graft, e.g., using a semilunar valve as a replacement, is an advantageous means over a prosthesis because the dimensions of the natural valves are optimal and most nearly equal or approximate those of the damaged valve; after endothelialization no prosthetic material remains exposed to contact with the blood stream; and there is substantial absence of any thrombogenic surface or joint, so that the risk of complications from thrombosis and emboli is minimized. The longevity of aortic homograft valve has been well demonstrated and fresh aortic homografts have not appeared to deteriorate with time.

Homografts have also been used as mitral and tricuspid replacement valves. However, in addition to difficulty with supply, these have posed some problems also. Some have exhibited small but undesirable stagnant areas in the flow patterns. In others, the shape of the ring, generally circular, does not sufficiently closely approximate the shape of the damaged valve; and in these circular devices also the flow may be therefore somewhat restricted because of reduced diameter. Also, inasmuch as the homograft valve prostheses are mounted on a fabric covered frame at the time of surgery, it is desired to perform this procedure in minimum time.

SUMMARY OF THE INVENTION

The valve device of this invention attains the above objectives and has other advantages. Particularly, where it has an oblong ring base, it more closely approximates the shape of certain damaged valves to be replaced, i.e., in the mitral position or area. In other words, there is better anatomical conformation of the ring support to the mitral annulus and of the two leaflets of the valve, to be more fully described below, in relation to the ventricular cavity than in the previously known tricuspid valve. It is a particular advantage of the bicuspid valve of this invention that two struts or prongs only extend into the ventricle, and the projection of a third prong into the outflow track is avoided. It is a further advantage that, having a two-pronged ring provided as a base, and having a fabric cover, the fabrication of the completed, tissue-covered valve at surgery is a simpler and speedier procedure. The oblong base bicuspid valve of this invention also enables good flow of blood through a larger orifice and with lower pressure drop than is obtainable with circular base supports, since more of the mitral valve area can be occupied.

The stent or support frame of this invention comprises a rigid frame (made of metal or of rigid plastic such as Delrin, Teflon, or Nylon) including as a base a ring of plastic or metal resistant to the action of and compatible with body fluids, and such ring having two struts or prongs extending from the upper or the lower face thereof to enable formation of two cusps with later-added tissue. Preferably, the ring with struts is of metal and is machined from one piece of commercially pure titanium in order to avoid possible corrosion at metal interfaces and also to avoid casting faults in the metal. A layer of fabric is contoured to and completely covers all the surfaces of the metal base. The fabric is non-absorbent or resistant to and compatible with body fluids and is preferably knitted of yarn or fibers and sewn to conform to the shape of the metal base frame. Tetrafluoroethylene (Teflon) fibers or yarn is especially suitable; but other suitable fabric, knitted or otherwise made, can be employed if desired. The fabric layer is provided with a first thickened portion at the apex of each strut, i.e., the end remote from the ring, a second thickened portion along the top edge of the frame, i.e., at the top of the ring and extending along the sides of the struts, and a third thickened portion, or sewing ring or flange, extending outwardly from the metal ring.

In the method of using the device of this invention, tissue, preferably autologous fascia lata, is wrapped around the support at the struts and the ends of the tissue strip are sutured together along the length of the strut. The tissue is also sutured to the second thickened portion along the top of the ring and at the sides of the struts thereby forming two leaflets of the valve. The tissue can also be extended over the sewing ring or flange and sutured thereto so that all prosthetic surfaces exposed to the ventricle are covered with homologus tissue. When emplaced in a heart, the two prongs of the stent extend from the valve seat into the ventricle at the sites of the anatomical commissures. The prongs simulate papillary muscles in reversed position, and extend only a short distance into the ventricle. The sewing ring is sutured to the annulus of the valve seat in the heart into which the valve replacement is being fitted. The operative lips of the tissue cusps or leaflets meet on a line parallel to the longitudinal center line of the base ring and can coincide with it or be offset from it.

The support ring can be used with autologous, homologous, and heterologous tissue, and, depending upon whether the ring base is oblong or circular, in any intracardiac position. It appears presently to be most advantageous when used with autologous tissue, such as a fascia lata graft taken from the patient.

BRIEF DESCRIPTION OF THE DRAWINGS

The device of this invention, its method of use, and some of the objects and advantages of the invention will be illustrated by the specific description of one embodiment thereof which is set forth below, and by the annexed drawings wherein:

FIG. 1 is a plan view of a metal base or support ring according to the invention.

FIG. 2 is a side elevation view of the ring of FIG. 1.

FIG. 3 is an end view of the ring of FIGS. 1 and 2.

FIG. 4 is a perspective view of a graft-support according to the invention, comprising a metal base ring covered with knitted fabric.

FIG. 5 is a top plan view of the graft-support of FIG. 4.

FIG. 6 is a cross-sectional view through a typical fabric-covered strut, taken on line 6--6 of FIG. 5.

FIG. 7 is a cross-sectional view through a fabric-covered ring, taken on line 7--7 of FIG. 5.

FIG. 8 is a side view showing a stent according to the invention in position to receive tissue and strip of tissue ready to be applied.

FIG. 9 is a top plan view of a valve replacement according to the invention showing juncture of cusps or valve leaflets.

FIG. 10 is a side view of the valve replacement of FIG. 9 showing suturing of leaflet at its base, to the underlying fabric of the ring support.

FIG. 11 is a perspective view of a bicuspid fascia lata valve according to this invention sutured into the mitral annulus of a heart.

FIGS. 12a, 12b, and 12c show schematically the relative shapes and relationships of the normal mitral valve, a prior art valve and the valve device of the present invention.

FIG. 13 is like FIG. 9 but shows an embodiment wherein the struts are displaced from the center line of the ring and provide one longer leaflet.

DETAILED DESCRIPTION OF THE INVENTION

In one embodiment of the device of this invention, a graft-support ring base 10 is machined in one piece from commercially pure titanium, to eliminate any likelihood of corrosion at the metallic interfaces and the presence of casting faults. The ring 10 in this embodiment is generally oblong in form, having a long diameter and a short diameter, and it is provided with a pair of prongs or struts 11, 11' which are preferably disposed opposite each other at each end of the long diameter and both of which extend in the same direction from the ring base 12. The struts 11, 11' are rounded off at the top and connect with the ring base 12 at their sides through a smooth curve, thus avoiding sharp corners or abrupt turns, as shown in FIGS. 2, 3, 4, 8 and 10. A typical ring base is shown in FIGS. 1, 2, and 3. The struts extend generally perpendicularly to the plane of the ring base or can be outwardly inclined at a small angle to the perpendicular, e.g., of from 2° to 5° thereto, and each is provided with an aperture 13 near its apex. The ring base 12 is also provided with suitable apertures 27 whereby fabric cover 14 is sewn to and anchored to the ring base.

The ring base 12 is fitted with a fabric cover 14, as shown in FIGS. 4 to 8, to provide a suturing anchor and to which both the tissue and the host heart are sutured. This cover 14 is preferably a knitted fabric compatible with and resistant to attack by body fluids, for example, knitted Teflon (tetrafluoroethylene) fiber. In FIG. 4 is shown a typical knitted Teflon-covered device 15 comprising the ring base of FIGS. 1-3 and bearing the fabric cover 14. FIG. 6 shows a sectional view through a strut 11 having fabric cover 14 which is thickened at the top of strut 11 to provide a first thickened portion 16 to which later-applied tissue, especially fascia lata tissue, is sutured. As shown in FIG. 7, the fabric 14 is doubled over at the top of the base ring 12 to provide a second thickened portion 17 to which the cusps or leaflet bases of tissue as later applied are sutured. A third thickened portion 18 extends outwardly from ring base 12, suitably at an angle of from 30° to 60°, preferably about 45°, to the perpendicular or central axis of the ring, and provides a suturing anchor or support for fixing to the host heart when emplaced therein, as in the mitral valve position. If desired, the fabric of the sewing flange can be partially quilted to stiffen it. Although the fabric has been described as being knitted Teflon, any other fabric, knitted, woven, felted or other can be employed which is compatible with the body fluids and of sufficient strength.

When the base ring has been covered with the fabric cover, a rectangular piece of tissue 19, preferably autologous fascia lata, is wrapped around the prepared stent, as shown in FIGS. 8, 9 and 10 and is sutured at its ends to form a tube or a tubular tissue covering around the struts and intervening space. The tissue is sutured to the second thickened portion of fabric 14 to form two cusps or leaflets 20, 20' of the valve replacement and their upper edges 21, 21', i.e., those remote from the ring 12, lie adjacent each other to form the valve opening. The fascia lata tissue extends also over the sewing flange outer surface so that, when placed in the host heart all surfaces exposed to the ventricular cavity are of homologous tissue or of autologous tissue. A pledget of Teflon felt is wrapped around the apex of each strut, the fabric covering and the tissue thereover to ensure coaptation of the leaflets 21, 21', and is fixed in place by suturing. The valve replacement 25 is now ready for insertion into the host heart, after testing to determine that the leaflets operate properly. Such testing can be done by the method and means described in the co-pending patent application of Angell et al. Ser. No. 726,288, filed May 3, 1968.

In the use and testing of the bicuspid valve of this invention, it has been found that the commissures during diastole separate approximately 2 millimeters, dropping the pressure gradient across the valve a little more than with prior art valve replacements and providing improved closure during systole. The anteromedial leaflet may be fabricated so that it is deeper than the lateral, thus becoming the principal leaflet during the functioning of the valve, such deeper leaflet being demonstrated in FIG. 13. In the embodiment of FIG. 13, struts 30, 30' are offset from the longitudinal center line of stent 31 and equidistant thereto, so that edges 21, 21' of leaflets 33, 33' are parallel to such center line. This has the result that one leaflet, 33', is longer or deeper than the other leaflet, 33, as described above.

FIG. 12a of the drawings shows a natural mitral valve 40 as occurring in a heart 41, having cusplets 42, 42', opening at 43. In FIG. 12b, the natural valve has been removed on line 44 and dotted line 45 indicates the shape of the circular base of the prior art, and lack of conformity can be seen. In FIG. 12c, the shape of the base 46 of the valve of the present invention can be seen to conform closely to the opening 44 in heart 41 which receives the valve replacement, cusplets 47, 47' meeting at line 48 to provide the valve opening during working of the valve.

The valve replacement 25 is inserted into the heart 41 to be treated, in a manner similar to that employed for the insertion of a prosthetic valve and to that described in the co-pending patent application of Angell et al, Ser. No. 726,288, filed May 3, 1968 and now U.S. Pat. No. 3,548,418. For mitral replacement No. 2-0 Tevdak sutures 35 are placed through the atrioventricular ring 36 of the patient, sixteen to twenty-two mattress sutures 35 being employed. When possible, the aorta is left unclamped and coronaries are perfused through the aortic root. If aortic cross-clamping is necessary, local hypothermia may be employed for myocardial protection.

The sutures 35 are placed through the sewing ring 18 and valve replacement 25 is pushed gently into position being absolutely certain that struts 11, 11' slide past the atrioventricular ring 35 and lie in the ventricle. After assuring that sutures 35 are straight, they are pulled up and tied into place.

Caution is exercised in placement and orientation of valve replacement 25 in a small ventricle to prevent compromising the left ventricular outflow tract, and the device should be placed as high as possible in the mitral annulus consistent with good placement. Left ventricle and ascending aorta may be vented with a 20-gauge needle through the cardiac apex and ascending aorta.

All patients with prosthetic material exposed to he blood stream are preferably anticoagulated for 2-3 months postoperatively. With Coumadin (Warfarin sodium, Endo Laboratories, Inc.) as an anticoagulant, prothrombin times are maintained at 20 ± 2 percent. Anticoagulants may be discontinued after a suitable period with the belief that the endothelialized surface will not form thrombus. Otherwise, patients can be treated as in any valve replacement, with gradually increasing activity.

The specific description and the drawings have been given for illustration only and modifications and variations can be made therein without departing from the spirit and scope of the appended claims. The ring base has been shown herein as oblong but it will be understood that a circular base ring can alternatively be used. The term "oblong" as used herein in the specification and claims is intended to mean a shape which is generally oblong, that is, which has a long diameter and a short diameter, but wherein the corners and contours are rounded to conform more nearly to anatomical contours.