US 3906549 A
An implanting structure and method according to which there is introduced into a body cavity different from the final location of the implant a structure having a general outline of the implant and on which the body tissue will grow. This structure is mounted in the latter body cavity in such a way that the tissue grows on the structure only from a predetermined feeding part of the structure with the remainder of the structure being maintained out of engagement with the body tissue. After this structure is separated from the tissue at the feeding part, with the structure covered with body tissue which has grown thereon, the structure with the body tissue thereon is situated at the desired location with a connection being provided at the feeding part so that the tissue which has grown will continue to be fed at the final location of the implant.
Description (OCR text may contain errors)
[451 Sept. 23, 1975 Elite States ateiit i 1 Bucalo [5 IMPLANTING STRUCTURE AND METHOD 3.745.995 7/1973 3/1 X Inventor: Louis Bucalo, l55 Roberts St.,
Primary E.\'aminerRonald L. Frinks Attorney, Agent, or FirmSteinberg & Blake  Filed: July 17, 1974  ABSTRACT An implanting structure and method accordin which there is introduced into a body cavit from the final location of the implant a str Appl. No: 489,444
g to y different ucture hav- Related U.S. Application Data  Continuation-impart of Ser. No. 425,805. Dec. 18,
ing a general outline of the implant and on which the body tissue will grow. This structure is mounted in the latter body cavity in such a way that the tissue 1973, abandoned. and a continuation-in No. 298.024. Oct. 16, 1972 grows on the structure only from a predetermined feeding part of the structure with the remainder of the struc-  Field of Search............ 3/
ture being maintained out of engagement with the b 32/10 A ody tissue. After this structure is separated from the References Cited tissue at the feeding part, with. the structure covered UNITED STATES PATENTS o u r t S e h t n o e r e h t n W o r g S a h h .w in W e u s S n y d o b h .n W
23 Claims, 9 Drawing Figures w t w m M VQ: ma ph g .mw h w m mm m ne Oh ct w hh .H wo S n n U& ap C 000 n 1 w r mk continue to be fed at the final location of the implant.
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IMPLANTING STRUCTURE AND METHOD CROSS REFERENCE TO RELATED APPLICATION This application is a continuationin-part of copending application Ser. No. 425,805. filed Dec. I8, 1973, and entitled Method and Material for Promoting the Growth of Animal Tissue, now abandoned, and a continuation-in-part of application Ser. No. 298,024, filed Oct. 16, 1972, and entitled lmplanting Method. now Pat. No. 3,826,241.
BACKGROUND OF THE INVENTION The present invention relates to implants of the type which are included in the body of a living being for replacing natural body components or for being combined with natural body components, as Well as to a method for building such implants and situating them in the body.
One of the major problems encountered with body implants is the problem of rejection. The body does not always accept foreign elements which are introduced into the body.
In order to avoid this problem it has already been proposed to grow directly in the body which requires the implant tissue which will form part of the implant so that an attempt is made in this way to avoid the rejection problem. However, up to the present time only extremely complex and impractical devices and methods have been proposed. For example it is known to situate in a body cavity a die having spaced walls between which tissue will grow, the die giving the tissue the required configuration and of necessity having a wall formed with openings through which tissue will grow into the interior of the die. Such devices and methods require not only a complex structure but also the severing of the die from the tissue which grows around the die and then the separation of the die from the tissue which grows in the interior of the die, so that undesirable complexities are involved with such known methods and devices.
Furthermore, where the implant is composed in part of body tissue which has been grown directly in the body which requires the implant, it is essential to continue to feed the grown tissue when the implant is situated at its final location, since otherwise the previously grown tissue will die. Considerable problems have been encountered with providing tissue in such a way that it will remain alive when the implant is connected to the body at the final desired location of the implant.
A further problem encountered with implants of the above general type is that the implant of necessity includes movable parts, and the tissue which is preliminarily grown to form part of the implant is not always adapted to carry out the movement which is required of the completed implant. so that failures undesirably occur. I v
In addition. it has been found that where the implant takes the form ofa valve or other device which requires a sealing surface, it is difficult to grow tissue in such a way that an effective sealing surface will be provided.
Furthermore, the time required for growing the tissue is undesirably long and the mounting of the implant at its final location is encumbered by the problem of growing the previously grown tissue together with. the tissue at the ultimate location of the implant.
The above problems are particularly apparent with a rclatnely complex implant such as a heart valve.
SUMMARY OF THE INVENTION It is accordingly a primary object of the present invention to provide a method and device which will avoid the above drawbacks.
In particular, it is an object of the present invention to provide a method for effectively growing tissue which will form an implant, in such a way that the tissue which is grown will reliably be fed with the required nourishment which will maintain the tissue in a living, properly operating condition when the implant is situated at its final location.
Furthermore, it is an object of the present invention to provide an implant of the above type which will have tissue which is adapted to the operating conditions required for the implant, such as are encountered when part of the implant must move.
Also, it is an object of the present invention to provide a method and device which will effectively provide sealing surfaces wherever required.
In addition it is an object of the present invention to provide a method and device according to which it is possible to accelerate the growth of tissue both during formation of the implant and during healing of the con nection between the implant and the tissue to which it is attached at the final location of the implant.
In particular it is an object of the present invention to provide an implant in the form of a heart valve as well as a method for forming such an implant and situating the latter'at the heart.
In accordance with the invention a cavity is formed in the body and a structure of the general outline of the implant is situated in this cavity. This latter structure has a'surfacc along which tissue will grow. The structure is connected to tissue in the cavity only at a predetermined feeding part of the structure while the re mainder of the structure is maintained out of engagement with the body tissue so that the tissue will grow from the body at the feeding part of the structure along the surface of thejstructure to cover the latter surface. Thereafter the structure with the tissue which has grown thereon is removed from the cavity with the structure being severed from the body tissue only at the feeding part where the connection was originally made with the structure. The removed structure with the tissue which has grown thereon is then situated at the final location where a connection is made with body tissue only at the feeding part, so that in this way the tissue which has previously grown will continue to be fed at the final location of the implant. I
BRIEF DESCRIPTION OF DRAWINGS The invention is illustrated by way of example in the accompanying drawings which form part of this application and in which:
FIG. I is a perspective illustration of one type of valve which will serve as a heart valve with FIG. 1 showing only the basic structure onto which tissue is subsequently grown:
FIG. 2 is a perspective illustration of a different type of heart valve and shows only the basic structure onto which tissue is subsequently grown;
FIG. 3 illustrates how the structure of FIG. 1 is treated so that tissue will grow over the surface of the illustrated structure;
FIG. 4 illustrates how the structure of FIG. 2 is treated so that tissue will grow over the surface of the illustrated structure;
FIG. 5 is a schematic illustration of the structure situated in a body cavity while tissue grows over the surface of the structure which with the tissue will form the implant;
FIG. 6 is a schematic transverse section of the structure shown in FIG. 5, taken along lines 6-6 of FIG. 5 in the direction of the arrows;
FIG. 7 illustrates how a valve of the type shown in FIGS. 2 and 4 is situated in a body cavity during growth of tissue, with FIG. 7 also showing a drive means for moving regions of the structure on which the tissue grows;
FIG. 8 is a schematic representation of the manner in which the implant removed from a body cavity of the type shown in FIGS. 57 is situated at the final location; and
FIG. 9 is a schematic wiring diagram of part of the arrangement shown in FIG. 5.
DESCRIPTION OF PREFERRED EMBODIMENTS Referring first to FIG. 1, there is illustrated therein a base structure which will form part of a heart valve of the invention. This base structure includes a ring 10 over which is located an arch 12. Thus, the arch 12 is ofa generally U-shaped configuration and has free ends formed integrally with the ring 10, the arch 12 being situatcd'in a plane normal to that which contains the ring 10. The arch 12 thus extends over an opening 14 which is defined by the ring 10. A ball member 16 is situated at the opening 14, being movable slightly with respect to the ring 10 for assuming open and closed positions where the opening 14 is respectively opened and closed. The arch 12 retains the ball member 16 in its operative position with respect to the opening 14.
The components l0, l2, and 16 may be made of any plastic or metal which are compatible with the body, and the ball member 16 may be solid or hollow, the parts being small enough and light enough so that the weight of the components does not form a material factor which must be taken into consideration.
Instead of a ball-type of heart valve base structure as shown in FIG. 1, is is also possible to use a cusp-type of structure as shown in FIG. 2. Thus the base structure which is shown in FIG. 2 includes a ring 18 which has integrally connected to its inner periphery a plurality of flexible resilient cusps 20. In the illustrated example there are three cusps 20 forming a tricuspid type of heart valve. The resiliency of the cusps 20 is such that they normally assume a closed position where they engage each other, these cusps responding in a known way to the pressure of the blood so as to open during pulsation of the blood, as is well known. In this case also the cusps 20 and the ring 18 formed integrally therewith can be made of any plastic or metal compatible with the body, and the sheet material used for the cusps 20 and ring 18 is relatively thin so that the entire weight of the basic structure shown in FIG. 2 is negligible.
In accordance with the invention the exterior surfaces of the structures shown in FIGS. 1 and 2 are treated so as to promote growth of tissue over these exterior surfaces. For this purpose it is possible, for example, to situate either the structure of FIG. 1 or that of FIG. 2 in a suitable evacuated atmosphere while a matcrial such as gold is sputtered onto the exterior surfaces to form at the exterior surfaces of the components shown in FIGS. 1 and 2 a layer of porous metal. Such a porous matrix forms a structure into which living tissue will readily grow and which will become covered with living tissue which grows along the exterior surface formed by such a layer.
In the particular examples shown in FIGS. 3 and 4, however, the exterior layer which promotes the ingrowth of tissue takes the form of wire which is wound around the exterior surface of the structures, as illustrated in FIGS. 3 and 4, this wire being extremely fine and made of a material such as stainless steel or gold so as to be compatible with the body. Thus, as may be seen from FIG. 3, the ring 10 as well as the arch 12 and the ball member 16 has a wire such as gold wire 22 wound all over the exposed surfaces to define between the intersecting windings small interstices which form pores into which living tissue will readily grow. It is to be noted that the wire which is wound around the ring 10 and the arch 12 has an extension 24 extending from the arch 12 to the ball member 16 so that the latter is connected to the arch by way of the flexible wire portion 24.
In the case of FIG. 4, the gold or stainless steel wire 26 is wound all around and pressed against the cusps 20 and the ring 18 in the manner illustrated so as to form the layer into which tissue will grow very readily as described above.
In accordance with the method of the invention the structure which is shown either in FIG. 3 or in FIG. 4
is then situated in the interior of a cavity which is created in the body at a suitable location different from the final implant location. Thus, FIG. 5 illustrates a body cavity 30 formed in a body of tissue 32 in any suitable way. The tissue 32 may be situated at an arm or a leg of the individual who is to receive the implant, although other locations are also suitable such as a buttock or any fleshy part at the region of the chest cavity, for example.
In accordance with the particular feature of the invention the structure of FIG. 3 or FIG. 4 is situated in the body cavity 30 in such a way that this structure is maintained out of engagement with body tissue except for a predetermined feeding part of the structure. In the embodiment of FIG. 3 the outer periphery 34 of the ring 10 forms the feeding part while in the embodiment of FIG. 4 the outer periphery 36 of the ring 18 forms the feeding part. In the example shown in FIG. 5 it is a structure of FIG. 3 which is shown in the body cavity 30. In order to maintain the structure of FIG. 3 in the body cavity 30 in the manner required by the present invention, a mounting means 38 is provided. This mounting means includes a pair of shell members 40 and 42. The shell member 40 is in the form of a hollow shell engaging tissue in the cavity 30 so as to maintain this tissue away from the upper part of the structure introduced into the cavity, as illustrated in FIG. 5. The shell 42, on the other hand, maintains the structure introduced into the cavity 30 out of contact with the tissue 32 at a lower part of the introduced structure, as viewed in FIG. 5. It will be noted that the shell 42 is smaller than the shell 40. The outer diameter of the upper peripheral edge of the shell 42, as viewed in FIG. 5, is somewhat smaller than the diameter of the feeding periphery 34 so that sutures can be provided between the body tissue 32 which adjoins the feeding periphery 34 and the ring at the periphery 34 in order to attach the structure introduced into the cavity 30 to the body tissue 32 only at the feeding part of periphery 34. These sutures will extend through part of the tissue 32 which is adjacent the periphery 34 and around the ring 10 which is covered with the wire 22 so that the tissue 32 will be maintained pressed against the periphery 34 by such sutures. If desired these sutures may be the type which after a given time become absorbed into the body so that they will simply disappear after tissue has grown over the ring 10. While the tissue 32 has an exposed surface 44 extending from the ring 10 up to the peripheral edge of the shell 40, this exposed tissue surface 44 will not engage any part of the introduced structure. As a result tissue will only grow first over the ring 10, then along the arch 12, and then along the flexible wire member 24 to the porous layer which covers the ball member 16. Thus all of the tissue which grows is necessarily fed only through the feeding part 34 situated at the outer periphery of the ring 10.
In accordance with a further feature of the invention, as is illustrated in FIG. 6, during the growth of tissue in the cavity 30 the ball member 16 is not maintained over of the ball member 46 so as to be formed by the smooth surface of the ball member 46 into a sealing surface which will cooperate properly with the ball member 16 in the final valve.
As may be seen from FIG. 6, the shell 40 has a projecting wall 48 on which the member 16 is located with the wire 24 extending from the arch 12 to the ball member 16 in the manner illustrated in FIG. 6. The smooth surfaced ball member 46 together with the wall or shelf 48 will maintain the ball member 16 reliably on the shelf 48 while tissue grows from the arch 12 along the wire 24 onto and covering the ball member 16.
Thus, with the method of the present invention the tissue will creep, during growth, along the fine wire to cover the valve. being fed through the feeding periphery.
Of course, it will be understood that the cusp-type of valve shown in FIG. 4 can be mounted in the cavity 30 in the same way as the structure illustrated in FIGS. 5 and 6 with the connection of the tissue being made in this case only at the feeding periphery 36, and tissue will in the same way creep along and cover the tricuspid type of valve. In this case, of course, there is no necessity for a flexible member such as the member 24 or a shelf or the like to temporarily support a member.
Thus, after the base structure of the implant has been situated in the body cavity in the manner described above, the cavity is closed and the structure remains in the cavity for a length of time sufficient for the tissue to grow over and cover the valve. Thereafter, the cavity is opened and the base structure with the tissue which has grown thereon is removed from the cavity. At this time the base structure with the tissue which has grown thereon is severed from the body tissue 32 only along the feeding part or feeding periphery. Thus, the tissue 32 ill be cut just slightl) beyond the outer periphery 34 of the ring 10 in order to separate the implant from the tissue 32 in order to remove the implant from the body cavity 30. Of course at this time the shells 40 and 42 are also removed and the cavity is closed so that the tissue will heal.
When the structure described above and shown in FIGS. 5 and 6 has been removed from the body cavity, the smooth surfaced ball member 46 is removed and the surgeon will now introduce the ball member 16 with the tissue which has grown thereon into the space between the ring 10 and the arch 12 so that the tissuecovered ball member 16 will now cooperate with the smooth tissue surface which has formed along the inner periphery of the ring 10 so as to form in this way the completed ball-type of heart valve. The time during which the tissue grows is such that a predetermined thickness of tissue forms without restriction while building onto the exterior surface of the basic structure, and an allowance is made for the thickness of the growth of tissue so that the opening defined by the ring 10 with the tissue thereon will be opened and closed by movement of the ball member 16 toward and away from the arch 12. The flexible tissue-covered member 24 will not interfere with this movement. The ball members 16 and 46 are compressible and elastic so that they can be introduced into and removed from the space between ring 10 and arch 12.
The removed implant is now situated at its final location in a manner which is shown schematically in FIG. 8. Thus FIG. 8 shows a wall 50 ofa heart where the implant is to be situated so as to replace the natural heart valve. The feeding periphery 34 is joined with the heart wall 50 by sutures 52, so that healing will take place along the feeding periphery 34 where the implant has been severed from the tissue 32 between this feeding periphery and the tissue which forms the wall 50. As a result of this healing the body will form suitable capillaries in the tissue so as to continue the feeding of the tissue which has previously been grown in the cavity 30. In this way the delivery of blood with nourishment continues throughout the tissue on the ring 10 and the arch 12 as well as through the tissue on the flexible member 24 to the tissue which covers the ball 16. In this way an implant having only living tissue grown from the body which receives the implant at the exterior of the implant is provided to eliminate any problem of rejection.
FIG. 7 shows the cusp-type of valve of FIG. 4 in the body cavity 30. As was indicated above, the cusps 20 are resilient so that they tend to assume due to their inherent resiliency a closed position. According to a further feature of the invention the shell 40 fixedly carries at its interior a plurality of drive means 54 connected by suitable wires 56 to the outer tip regions of the cusps 20. The plurality of drive means 54 may take the form, for example, of small solenoids which when energized will provide an outward pull on the wires 56 pulling the cusps 20 outwardly toward their open positions. These small solenoids are only energized for a small period of time so that almost immediately after being pulled to their open position the cusps 20 are released to return due to their own resiliency to the closed position with the solenoids being decnergized. A suitable power source 58 is also connected to the inner surface of the shell 40 in the example of FIG. '7. This power source 58 will include a suitable battery which drives a small motor which serves to open and close a switch at predetermined intervals, electrical connections being made through suitable conductors 60 to the plurality of drive means 54 so that these drive means are periodically energized. For example, it is possible to provide through the power source 58 and the timing structure driven thereby a series of impulses which will energize the solenoids which form the drive means 54 once every half hour, for example, so that in this way during growth of tissue onto the cusps they are flexed once during each half hour from their closed to their open positions and then released to return to their closed positions.
As a result of this feature of the invention during the growth of tissue onto the cusps 2 0, these cusps 20 carry out movement closely simulating the movements which will be required of the cusps 20 when the valve is situated at its final location, and thus the tissue grows in such a way that it adapts itself to the required movement of the cusps. As a result when the valve is situated at its final location the tissue which has grown onto the movable parts will be capable of withstanding the stresses required by the movement, and thus undesir able breakdown of the tissue due to such stresses will be reliably avoided.
With the embodiment of FIG. 7 when a sufficient time has elapsed for the tissue to grow over the base structure shown in FIG. 4, the valve is removed in the manner described above, by severing the tissue at the region of the feeding periphery, and at this time the wires 56 are severed at the region of the outer tips of the cusps 20, so that the resulting implant is then introduced in the manner described above in connection with FIG. 8 into the heart.
It is known that is is possible to enhance and accelerate the growth of tissue by situating the tissue during growth in an electrical field such as an electrical magnetic field or an electrostatic field which is periodically created. Thus, FIG. 7 shows how the shell 40 carries at its interior a pair of diametrically opposed units 62 which will create between these units an electrical field in which the tissue grows. For example, each of the units 62 may include an inductance coil situated with respect to the cusps 20 in such a way that when these coils have current flowing therethrough there will be created between the units 62 an electrical field which will accelerate and enhance the growth of tissue. Such inductance coils may be periodically supplied with current from a capacitor which is first charged from a battery situated in the units 62 and which is then periodically discharged while supplying the inductance coil with current. For this purpose each unit 62 will include a suitable drive which first opens a switch to the inductance coil while closing a switch between the battery and capacitor to charge the latter and which then opens the latter switch while closing the switch between the capacitor and induction coil so that the capacitors are charged periodically and are then discharged periodically through the inductance coils to create in this way the electrical field in which the tissue is situated. These procedures will reduce the time required for the tissue to grow and will encourage a profuse growth of healthy tissue.
As is shown in FIG. 8 similar units 62 may be situated on opposite sides of the location where the implanted valve is sutured to the wall 50 so that the same type of electrical field can be periodically created to accelerate the healing at the feeding periphery.
In addition, it is possible, as indicated in FIGv 9, to provide a circuit where the tissue to be electrically acted on simply forms a resistor in a closed circuit which includes a battery and a switch 72 for opening and closing the circuit. With such an arrangement also the healing of tissue and growth thereof will be enhanced. Thus, as is shown in FIG. 5, the battery 70 and switch 72 may be incorporated in a suitable housing 74 situated within the shell 40 as schematically illustrated in FIG. 5. A pair of conductors extend from the housing 74 and terminate in a pair of electricaly conductive probes or prongs 76 which are inserted into the tissue in the manner shown schematically in FIG. 5. Thus the unit 74 together with the elements 76 and the conductors connected thereto form in FIG. 5 the circuit illustrated in FIG. 9 according to which the tissue situated between the elements 76 form a resistor completing the circuit and enabling the electrical action to take place at the location where the tissue grows so as to enhance the tissue growth.
Of course it is to be understood that while in the above-described structure specific reference has been made to heart valves, the principles of the invention are of general applicability and may be used with many different types of implants.
What is claimed is:
1. An implanting method comprising the steps of creating a cavity in the body of a living being at a location different from the location where an implant is to be situated, introducing into the thus-created cavity a structure having the general outline of the implant and having an exterior surface along which tissue will grow, connecting a predetermined feeding part of the structure to tissue in the cavity while maintaining the remainder of the structure spaced from tissue in the cavity so that body tissue will grow from said feeding part of said structure over the surface thereof to cover said surface, closing the cavity and thereafter opening the cavity after the structure has remained therein for a time sufficient for tissue to cover the surface of the structure, then severing the structure from the body tissue at said predetermined feeding part of the structure and removing said structure with the tissue which has grown thereon from the cavity. and then implanting the structure with the tissue which has grown thereon at the final location of the implant while connecting the structure with the tissue which has grown thereon to living tissue at the final implant location at the feeding part which was severed from tissue in the body cavity, so that the feeding of the living tissue of the implant will continue at the final implant location.
2. The method of claim 1 and wherein the structure which is introduced into the body cavity has a peripheral edge which forms said feeding part so that the tissue grows from said peripheral edge of said structure over the latter at the exterior surface thereof.
3. .The method of claim 1 and wherein the structure which is introduced into the cavity includes a member having the general outline of the implant, the step of covering the exterior surface of said member with a layer of a material compatible with the body and having a porosity sufficient to promote the ingrowth of tissue into said layer, said member and said layer forming the structure which is introduced into said cavity.
4. The method of claim 3 and wherein said member is covered with a fine wire mesh which forms said layer.
5. The method of claim 4 and wherein a fine wire is wound onto the exterior surface of said member to form said mesh with the latter creating between the wire windings interstices which form fine pores into which the tissue will grow.
6. The method of claim 1 and wherein a space is maintained in said cavity surrounding the structure introduced into the latter at substantially all parts of the structure except the feeding part which is connected to said tissue with said space having a magnitude great enough to provide for unrestricted build-up of tissue on said surface so that the tissue which grows has an exterior surface exposed to said space.
'7. The method of claim 1 and wherein the implant in cludes a portion which is required to move when the implant is situated at its ultimate location, and connecting to said structure at a region thereof which will form said movable portion of said implant a means which pe riodically moves said region of said structure while tissue grows thereon to form said movable implant portion, so that the tissue grows under the conditions of movement which will be required for the implant, to develop characteristics suitable for said movement.
8. The method of claim 1 and including the step of situating the structure in said cavity during growth of tissue thereon in an electrical field which accelerates the tissue growth.
9. The method of claim 1 and including the step of situating the feeding part of the implant which is connected to tissue at the final location of the implant in an electrical field which promotes the growing together of the feeding part of the implant with the tissue to which it is connected.
10. The method of claim 1 and wherein the structure has at a given region thereofa movable member having an exterior surface on which tissue will not grow but which is engaged by tissue which grows at said given region so that the tissue which engages said member will i have a smooth outer surface capable of forming an effective sealing surface.
ii. The method of claim l and wherein the implant is a heart valve.
12. The method of claim 11 and wherein the struc ture introduced into the cavity includes a ring having an outer periphery forming said feeding part ofthe structure, an arch extending over said ring, and a ball member for releasably closing an opening defined by said ring and to be retained at said opening by said arch, and a flexible member extending between said arch and said ball member so that tissue will grow from said arch along said flexible member to the exterior of said ball member.
ill. The method of claim 11 and wherein said valve includes a plurality of cusps which move away from and back toward each other during opening and closing of the valve and connecting to the structure at regions which form said cusps a means for periodically moving said regions during growth of tissue thereon.
14. A device for forming an implant which will include living tissue. comprising a structure having the general outline of the implant and provided with an exterior surface on which tissue will grow, and mounting means for mounting said structure in a body cavity with only a predetermined feeding part of said structure connected to body tissue while said mounting means maintains the remainder of the structure spaced from the body tissue.
15. The combination of claim 14 and wherein said mounting means includes a pair of hollow shell members which define between themselves a space in which said structure is situated, and said structure extending at said feeding part thereof beyond one of said shell members to be connected directly to the body tissue.
16. The combination of claim 14 and wherein the implant has a movable portion. and drive means operatively connected with that region of the structure which will form the movable portion of the implant for periodieally moving said region of said structure so that while tissue grows on said region the movement thereof simulates the conditions under which the implant will be required to operate.
17. The combination of claim 14 and wherein said structure is a heart valve.
18. The combination of claim 17 and wherein said heart valve includes a ring, an arch extending over said ring, a ball member for opening and closing an opening defined by said ring and adapted to be retained by said arch at said opening, and a flexible member extending between said arch and ball member so that tissue will grow along said flexible member from said arch to said ball member, said ring having an outer periphery which forms said feeding part of the structure.
19. The combination of claim 17 and wherein the heart valve includes a ring having an outer periphery forming said feeding part of the structure and a plurality of cusps movable with respect to and connected to an inner periphery of said ring, and drive means operatively connected to said cusps for periodically moving the same.
20. The combination of claim 18 and wherein a sec ond ball member having a smooth exterior surface on which tissue will not grow is situated at said opening to engage tissue growing at the inner periphery of said ring to form a smooth sealing surface from said tissue.
21. The combination of claim 14 and wherein a part of the tissue is to form a sealing surface and said structure including a member having a smooth exterior surface on which tissue will not grow and located at the region of said structure where the tissue which forms said sealing surface grows so that the latter tissue engages said smooth surface of said member to form the sealing surface.
22. The combination of claim 14 and wherein an electrical means cooperates with the structure for situating the latter in an electrical field which will promote the growth of tissue.
23. The method of claim 1 and including the step of situating the feeding part of the implant which is connected to tissue at the final location of the implant in an electrical circuit where said feeding part forms a resistor of said circuit.