Heart Valve Construction Having A Collagen Cover Encapsulation Thereon

Abstract

An autogenous heart valve with three leaflets is formed by a mold having slick back-up segments positioned behind each leaflet while the heart valve is implanted in the human body until a collagen covering has been formed; the heart valve so formed is removed from the host body, the excess collagen and mold are removed and the valve is implanted in the correct valve position in the heart.

Description

BACKGROUND OF INVENTION

1. Field of the Invention

This invention relates generally to a heart valve mold construction, and specifically to a method for making a heart valve construction of autogenous character, and resistant to clotting.

2. Description of the Prior Art

When a human heart valve is damaged, and particularly when it ceases to perform efficiently the necessary functions, operations may be performed which repair the defective valve by substituting an artificial valve for the natural valve. There are several heart valves available for this operation. The operations may fail because of several reasons such as disintegration of the substituted valve. The valve is subjected to great stress, in that it must cycle approximately 40 million times a year. This stress can destroy red blood cells (hemolysis) and produce persistant anemia and jaundice. Another cause of failure is the formation of blood clots on various surfaces of the valve and its vicinity. These clots get into the blood stream, and may block the flow of blood. The present invention addresses itself to this last problem.

Various solutions to the problem have been offered. In some cases, blood clots are sought to be avoided by using materials which resist clotting or have been treated with an anticlotting agent. Yet artificial cloth valves incorporating leaflets, copying the natural structure of the heart valve have frequently failed, because they tend to form clots.

SUMMARY OF THE INVENTION

It has been found that a heart valve construction can be devised which is capable of performing 40 million cycles a year, and which will be compatible with its host. A steel ring with three leaflets forming a valve gate forms an efficient valve structure. This structure when implanted in the body, receives a collagen sheath which closes the interstices of the fabric. The trifoliate structure being formed in its host, is compatible and is not subject to rejection when implanted in the heart tissue. The use of a mold with slick surfaces bearing on the leaflets as the collagen deposits, has been found to prevent clotting, by imparting a smooth ventral surface to the leaflets.

DRAWINGS

The foregoing objects and advantages as well as other objects and advantages may be obtained by the device shown by way of illustration of the drawings in which:

FIG. 1 shows a ring of stainless steel with three integral posts with holes,

FIG. 2 shows the ring with a fabric covering and three fabric leaflets attached,

FIG. 3 shows a fabric leaflet dimensioned to fit within the center of the ring, with a top hem containing an attachment thread,

FIG. 4 is a top plan view of the fabric covered ring with the leaflets sewn to the ring and the posts; and the threads attached to the posts;

FIG. 5 is a side elevational view of a trifoliate mold,

FIG. 6 is a top view of the trifoliate mold,

FIG. 7 is an inside elevational view of the tapered portion of one of the segments of the mold, and

FIG. 8 is a bottom view of a mold segment.

PREFERRED EMBODIMENT

Referring now to the drawings in detail. A stainless steel ring 11 is prepared, having a dimension suitable approximately to being attached to the heart structure in place of the natural valve located there. The ring 11 is provided with three arcuate portions to conform with the corresponding section of the aorta to which it will be attached. Three upstanding posts 12 are formed on the ring, generally disposed in parallelism with the central axis of the ring 11. A fabric sheath 13 is applied to completely cover the ring 11 and the posts 12. The fabric is preferably Dacron, Teflon, Polypropylene or Polyethylene. The fabric can be woven for example from a filament produced by the United States Catheter and Instrument Company, catalog number 6102, denier number 30, 015 mm. thick. Other synthetic inert filaments may be used to form this fabric. These synthetic filaments should be embodied in a fabric which is flexible, has an open mesh, is strong, is non-carcinogenic, and resistant to disintegration when exposed to human tissues. The fabric sheath 13 can be applied by wrapping a fabric around the ring 11 and the posts 12, and sewing it thereon to cover the ring and the posts. The fabric also can be applied by fusing the synthetic fibers together, preferably at their edges where they come together.

Three fabric leaflets 14 are prepared with one arcuate edge 10 and one generally straight edge. The straight edge has a hem 9, and a thread or tie 8 is passed through it. The arcuate edge is attached to the ring 11 and to the posts, and the thread 8 is passed through and tied to an eye or orifice 7 in the posts, thereby holding the leaflets 14 upright in such a manner that their other upper edges may all meet together as shown in FIG. 4 forming a closure for the valve, closing to ventral back pressure, but yielding to dorsal pressure.

Another way of forming the leaflets is to set the leaflets by the application of heat, so as to give the edges of the synthetic fibrous leaflets a normally self-sustaining character. In this manner, the leaflets 14 will yield to fluid pressure in one direction, but fluid pressure if exerted in the opposite direction, will press the hemmed edges 9 together and resist the back pressure. In this manner, a one way valve is devised by reason of the engagement of the leaflets 14 with each other, and forming a resistance to back pressure. The leaflets 14 will resist deflection, and the back pressure will cause them to engage with each other as a closure. In case the leaflets 14 are not shaped, but a thread is used to hold them, the attachment of the thread 8 to the post 12 will also inhibit the leaflets 14 from yielding to reverse pressure. The sheath 13, and the leaflets 14 are formed of a fabric having an open weave so as to be porous or penetrable for the reason hereinafter set forth.

The valve construction is then implanted in the human body, where it will not interfere with normal functions of the tissues or the activity of the host, for example under the skin of the abdomen. A stringy protein is formed by the bodily defense mechanism. This protein is called collagen. On smooth surfaces, it forms with a stringy texture making it strong longitudinally and weak laterally. However, on a rough textured surface such as the loosely woven fabrics surface, the collagen invades the interstices of the fabric and forms a strong sheath. It takes on something of the texture of the surface to which it is applied. After five weeks implantation in the host the valve is mature enough to be removed. The collagen deposit entirely incapsulated the valve structure and has filled the leaflets 14. The flanges or hems 9 are split from engagement with each other. The valve is then implanted in place of the defective heart valve, and it is sutured in place. If it is desired, the leaflets may be compressed between mating dies, so as to impart a smooth surfaces to the leaflets to discourage the formation of blood clots on their ventral surfaces. The dorsal surfaces, being constantly swept in the blood stream are not so inclined to the formation of the blood clots.

An alternative procedure to compressing the ventral surfaces is to cover each of them with a die 30 at the time of the implant. The die or segment 30 has a semicylindrical exterior face 31, and a slick inner face 32 which tapers smoothly to an arcuate botom edge 33. The inner face 32 conforms generally to the normal position of a leaflet 14 when it acts as a closure in the heart valve. The top of the segment 30 has slick interior flat radial faces 34 and a flat top 36, with a threaded hole 35. A disc 37 holds three of the segments 30 with screws 38. The segments 30 are spaced from each other so as to receive the three leaflets 14 mounted on the ring 11 inbetween them, with the slick inner faces 32, 34 bearing on the leaflets 14. This imparts a generally self-sustaining, normally closed character to the collagen coated leaflet 14, while the slick ventral inner faces 32 and the radial faces 34 form corresponding slick surfaces on the leaflets 14 that supply no place for clots to form, that might detach themselves and plug blood passages. After the collagen ages, it forms a psuedo intima which is a substantial replica of the original natural valve construction. It is capable of long functioning, and its surface is normally repaired by natural processes. As an autogenous body, it is not subject to rejection.

The valve being implanted in the fatty tissue, with the mold as shown in FIG. 5 embracing the ventral faces of the leaflets 14, the collagen soon forms and the valve is removed from the host. Excess collagen coating the valve is trimmed off and the mold is removed. The valve is then implanted in the correct aortic valve position in the same patient in whom it was previously implanted for the formation of the collagen.

Claims

I claim:

1. A heart valve construction comprising:

a. a ring,

b. three posts on the ring generally parallel to the axis of the ring,

c. an orifice in the top of each post,

d. an open mesh fabric cover on the ring and posts,

e. three arcuate edged fabric leaflets attached to the ring and the posts,

f. a top hem on the leaflets,

g. a tie passed through the hem,

h. opposite ends of the ties attached to the orifices,

i. a collagen cover on the ring, posts, cover and leaflets,

j. a slick collagen ventral face on each leaflet.

2. A heart valve construction according to claim 1, and the arcuate edges of the leaflets positioned on two posts and the intervening portion of the ring.

3. A heart valve construction according to claim 1, and the ties of sufficient length to hold the leaflets upright and to permit their upper edges and hems to meet together to form a closure responsive to ventral back pressure, but yieldable to dorsal pressure.