CA1327678C

CA1327678C - Multi-segmented annuloplasty ring prosthesis

Info

Publication number: CA1327678C
Application number: CA000615183A
Authority: CA
Inventors: Alain Carpentier; Hung L. Lam; Than Nguyen
Original assignee: Baxter International Inc
Current assignee: Edwards Lifesciences Corp
Priority date: 1988-12-22
Filing date: 1989-09-29
Publication date: 1994-03-15
Anticipated expiration: 2011-03-15
Also published as: DE68904887D1; DE68904887T2; US4917698A; JPH02213341A; EP0375181B1; EP0375181A1; JP3049359B2

Abstract

ABSTRACT OF THE INVENTION

A ring prosthesis which provides different flexibilities at various points about the circumference of an associated heart valve. Specifically, the annuloplasty ring prosthesis of the invention includes a segmented body formed by two or more segments. The individual segments form a body which is substantially circular and shaped proportional to fit about the annulus of the associated heart valve. The individual segments are held in position with respect to each by a flexible joint.
This flexible joint is formed by covering the segments with a flexible material which fits snugly about the segments. The cover is tied off between the adjacent segments to further restrain movement of the segments with respect to each other.

Description

` HULTI-SEGMENTED ANNULOPLASTY RING PROSTHESIS
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BACKGROUND OF THE INVENTION
-The present ~nvent~on relates to a support for a natural human heart which may be used for the surg~cal correct~on of a deformed heart valve, and in particular a d~lated heart vatve.
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The human heart generally includes four valves with the more critical of these valves being the tr~cusp~d valve. The tr~cusp~d valve is located ~n the r~ght atrloventr~cular open~ng. The other ~mportant valve ~s the m~tral valve Nhk h ~s located ~n the left atr~oventr~cular open~ng. Both of these valves are ~ntended to prevent regurg~tation of blood from the ventr~cle into the atrium when the ventrlcle contracts. In prevent~ng blood regurg~tat~on, both valves must be able to ~ w~thstand considerable back pressure as the ventr~cle ; contracts. The valve cusps are anchored to the muscular wall of the heart by del~cate but strong ftbrous cords ~n order to support the cusps durlng ventrlcu1ar contract~on. Furthermore, the geometry of the heart valves ensures that the cusps overlle each other to ass~st ~n controlllng the regurg~tat~on of the blood dur~ng ventr~cular contract~on.

Diseases and certa~n natural defects to heart valves can ~mpa~r the funcff on~ng of the cusps ~n prevent~ng regurg~tat~on. For example, certa~n diseases cause the d~lat~on of the heart valve annulus. Th~s dilat~on results ~n the d~stort~on of the valve geometry or shape dlsplac~ng one or more of the valve cusps from the center of the valve. The d~splacement of the cusps away from the center of the valve results ~n an ~neffective closure of the valve dur~ng ventr~cular contract~on. Th~s results ~n the regurgltat~on or leakage of blood dur~ng ventrkle ~ , , .

contraction. Diseases such as rheumatic fever or bacter1al inflammations of the heart tissue can cause d~stort~on or dilation of the valvular annulus. Other diseases or malformations may result in the distort;on of the cusps.

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~; 5 One method of repairina impaired valves ~s the complete surg~cal replacement of the valve. This method ~s particularly su~table when one of the cusps has been severely damaged or deformed.
~ However, presently available artificial heart valves are not as - durable as natural heart valves, and it is usually more preferable if the patient's heart valve can be left intact.

~h~le it is d~fficult to reta~n a valve w~th d~seased or deformed cusps, presently pract~ced methods prov~de for the ab~lity to surgically correct d~lated valve annulus. In v~ew of the durab~lity factor ~ith art~fic~al valves it ~s desirable to save the valve instead of perform~ng a complete replacement.
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These techn~ques for repalring d~lated or elongated valve annulus are generally known as annuloplasty, ~h k h ~s a surgical 20 procedure for constraln~ng the valve annulus dilat~on. In thls procedure a prosthes~s ls sutured about the base of the valve leaflets to restr~ct the dilated valve annulus. The prosthes~s restr~cts the movement of the valve annulus dur~ng the open~ng and clos~ng of the valve. Prosthes~s used in annuloplasty are ~5 des~gned to prov~de suffklent r~gid~ty to adequately support the valve annulus ln an effort to fac~litate the heal~ng of the Zvalve annulusl ~h~le also prov~d~ng suff~c~ent flex~b~lity to 'resemble, as close as poss~ble, the natural movement of the valve annulus dur~ng the open~ng and closing of the valve. Thls 30 ls partlcularly ~mportant since prosthes~s are normally retalned, even after the heallng of the valve annulus.

''~ '"' Over the years different types of prosthesis have been developed for use in annuloplasty surgery. In general prosthes~s are annular or partially annular shaped members whlch flt about the base of the valve annulus against the leaflets. Init~ally, the prosthesis ~ere des~gned as rigid frame members. The in~t~al concern was to develop a prosthes~s wh~ch s~gniflcantly restricted the dilation of the valve annulus. These annular prosthesis were formed from a metall~c or other r~gid material, ~hich flexes little, if at all, during the normal opening and closing of the valve. Examples of r~gld annuloplasty rlng prosthesis are disclosed ~n U.S. Patent Numbers 3,656,185, ~ssued to Carpentier on April 18, 1972; and 4,164,046, ~ssued to Cooley on August 14, 1979.

Certa~n art~ficial heart ~talves have also been developed w~th `~ 15 rigid frame members having a r~gldlty sim~lar to the r~g~d~ty of the descr~bed valve prosthesis. An example of this type of heart valve are d~sclosed ~n U.S. Patent Numbers 4,204,283, ~ssued to Bellhouse et al on May 27, 1980; and 4,306,319, issued to Kaster on Decembér 22, 1981.
As stated, a r~gid annuloplasty rlng prosthes~s adequately restricts valve dilat~on to promote the heallng of the valve annulus~ However, th~s r~gid~ty prevents the normal flexib~l~ty of the valve annulus. That ls, a normal heart valve annulus ~ 25 conttnuously flexes durlng the cardiac cycle, and a rig~d r~ng $ prosthes~s ~nterferes w~th th~s movement. S~nce lt ~s standard ,~ to reta~n the prosthes~s, even after the valve annulus has healed, the r~gld~ty of the prothes~s w~ll permanently impalr the funct~onlng of the valve. Another disadvantage with a r19~d ring prosthes~s ~s the tendency for the sutures to become torn loose dur~ng the normal movement of the valve annulus.

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Other workers have suggested the use of completely flex~ble annuloplasty ring prosthesis, in order to overcome the disadvantages of rigid ring prosthesis. Th~s type of prosthes~s -is formed with a cloth or other very flex~ble material frame member. The result~ng prosthesis provides l~ttle, ~f any resistance to the dilation of the annulus during the open~ng and closing of the valve. While these types of annuloplasty r~ng prothesis offer increased flexibility, such prosthesis fail to correct that valve d~sfunction due to the dilatlon of the valve annulus.

Examples of completely flexible r~ng prosthes~s are disclosed ~n U.S. Patent Number 4,2SO,151, ~ssued to Massana on September 22, 1981, and are discussed ~n the artkles of Carlos D. Duran and Jose LUi5 M. Ubago, "Clinical and Hemodyman~c Performance of a ~15 Totally Flex~ble Prosethetlc R~ng for Atrioventricular Valve ¦Reconstructlon", 5 Annals of Thorac~c Surgery, (No. 5), 458-463, ~November 1976) and M. Pu~g Massana et al, "Conservat~ve Surgery of the M~tral Valve Annuloplasty on a New Ad~ustable R~ng", Cardiovascular Surgery 1980, 30-37, tl981).
; 20 St111 other ~orkers have su~gested annuloplasty r~ng prosthesis ~hlch are ad~ustable, e~ther during the surgical ~mplantat~on, or as the r~ng prosthes~s durlng the open~ng and clos~ng of the ivalve. Thls type of ad~ustable prosthes~s ~s typ~cally des~gned ~n comb~nat~on ~ith a rigid, or at least part~ally r~gld frame 'member. For example, the ring prosthes~s taught ~n U.S. Patent Number 4,489,~446, ~ssued to Reed on December 25, 1984, allows for self ad~ustment of the prosthests annulus by constructlng the valve frame member as two rec~procaff ng pleces. However, ~hile the result~ng prosthes~s self ad~usts in at least one d~rect~on, the ~nd~vldual frame members are formed from a rlg~d mater~al. ~hus the proslthesis suffers the same dlsadvantages as the above d~scussed rig~d r~ng prosthes1s.

Other examples of adjustable ring prosthesis are taught ~n U.S.
Patent Numbers 4,602,911, issued to Ahmadi et al and 4,042,979, issued to Angell on August 23, 1977, provlde for mechan~sm of adjusting the ring circumference. In Ahmadi et al the rlng prosthesis frame ~s a coiled spr~ng r~bbon wh~ch ls ad~usted by a mechanical screw assembly. In Angell, a drawstr~ng ls used to ad~ust the c~rcumference of a rlgid frame member. Aga~n, these ring prosthesis suffer from the d~sadvantages of the r~g~d r~ng prosthesis discussed above.

A further disadvantage w~th the Angell prosthes~s relates to the design of the ad~usting mechan~sm. The Angell prosthes~s includes a rig~d part~al annular member. The open end of th~s member forms a gap which can be narrowed by tighten~ng the drawstring. The tighter the drawstring ls pulled the narrower the gap. The stress appl1ed to the r~ng prosthes~s dur~ng the open~ng and clos~ng of the valve ~s pr~mar~ly directed to the drawstring. Thus fa~lure of the drawstr~ng allows the prosthes~s annulus to expand, allowing the valve to dilate.

It ~ould thus be advantageous to design an annuloplasty rlng prosthesis hav~ng an annular frame member wh~ch more closely reflects the naturally flex~b~l~ty of the valve annulus, wh~le prov~d~ng for a sufff c~ent degree of rlgid~ty to res~st d~lat~on of the valve during the card~ac cycle.

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An annuloplasty ring prosthes~s whk h was deslgned ~n an attempt to provide f~r an elast~c~ty closely resembl~ng that of a natural heart valve ~s taught ln U.S. Patent Number 4,055,861, ~ssued to Carpentler on November 1, 1977. The annuloplasty rlng prosthesis taught ~n Carpentier ~s descr~bed as be~ng deformable, to an equal degree and simultaneously ~n all d~rections w~thin and oul:s~de its resting plane, so as to form a A
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skew curve. The preferred support is described as having the elasticity of an annular bundle of 2 to 8 turns of a cylindrical bristle of poly(ethylene terephthalate). In describing the support the individual bristles may either be interwoven, or merely arranged in a side by side relationship. The extremities of the individual bristles h~ are joined together by welding, gluing with an adhesive or .~ ligation .
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The resulting ring prosthesis of carpentier '861 will have a single degree of flexibility, which is dependent upon the flexibility of the individual bristles, and/or the number of these individual bristles used to construct the support.
Thus this device will either be rigid or completely flexible, in either case such a ring prosthesis would have the disadvantages associated with such types of ring prosthesis.
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It would thus be desirable to provide a ring prothesis which provides for a more natural flexibility of the valve annulus without suffering the above discussed -disadvantages.

SUMNARY OF THE INVENTION
An aspect of the invention is as follows:
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An annuloplasty ring prosthesis comprising:
j a body which defines a substantially circular shaped ; 30 ring proportioned to fit about the annulus of a heart valve, said body being formed from two or more segments, each of which is formed with opposing ends;
a flexible covering fitted about said segments to position each of said segments ends adjacent to an end of another of said segments, with said ends remaining unconnected: and .~ ~
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6a means associated with said covering for snugly holding said covering about said adjacently positioned ends.

The present invention overcomes the above discussed ` 5 disadvantages by providing a ring prosthesis which provides different flexibilities at various points about the circumference of an associated heart valve. Specifically, an annuloplasty ring prosthesis embodying the invention includes a segmented body formed by two or more segments.
The individual segments form a body which is substantially circular and shaped proportional to fit about the annulus r~ of the associated heart valve. The individual segments are held in position with respect to each other by a flexible joint~ This flexible joint is formed by covering the segments with a flexible material which fits snugly about the segments. The cover is tied off .

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between the adjacent segments to further restrain movement of the segments w;th respect to each other. In one embodiment the ~ segments are linked together by a flexible cord. ~he cover - may also function as a suture ring to provide a s~te for suturing of the prosthesis about the heart valve annulus.

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~- DESCRIPTION OF THE DRA~INGS

The present invent~on may be better understood and the ~"l advantages ~ll become apparent to those sk~lled ~n the art by reference to the accompanying draw~ngs, where~n l~ke reference numerals refer to l~ke elements ~n the several flgures, and ~here~n:

FI~URE 1 is a top ~ew of one embodiment of an annuloplasty r~ng lS prosthesis, ~th the cloth covering being partial1y removed to expose the individual segments;
. , FIGURE 2 ts an enlarged v~e~ of a port~on of a sect~on of the rlng prosthes~s of FIG. 1 expos~ng some of the segments and ~llustrat~ng the flex~ble ~oint and manner by wh~ch such segments are l~nked together us~ng a cord; and , FIGURE 3 ~s a top ~e~ of another embod~ment of an annuloplasty ring prosthesls, w~th the cloth cover~ng belng partlally removed to expose the ~ndlvidual segments and the flex~ble ~o~nt.
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DESCRIPTION 0~ THE PREFERRED EMBODIMENTS

The present ~nvent~on ~s d~rected to annuloplasty r~ng prosthesis ~hlch are formed to f~t about the base of the valve cusps of e1ther a bk usp~d or tr~cuspld valve. The r~ng prosthes~s of the ~nvent~on ~s formed from two or more segments wh~ch are held ~n posltlon w~th respect to each other by a flex~ble ~olnt. Th~s flexlble ~o~nt allows ad~acently posttloned segments to sllghtly bend along th~s ~oint.

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When the ring prosthesis is secured ~n pos~t~on about the valve, the individual segments move substantlally independently of each other, bending at the flexible ~o~nt. By the appropr~ate use of different sized segments, and d~fferent number of segments, prosthesis can be deslgned w~th d~fferent degrees of flex~b11~ty about their circumference. Furthermore, by approprlately positioning the individual segments the flexlb~l~ty can be positioned at those areas of the valve annulus requ~r~ng a greater degree of flex~bility.
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For example, it has been determined that ~t would be benefical to prov~de a ring prosthes~s hav~ng greater flex~bility at those ~ locaff ons ad~acent to that region of the valve whereat the cusps - overlap. A r~ng prosthes~s for use w~th a b~cusp~d valve can be des~gned w~th at least two portions ~oined together by two 1~ flex~ble ~o~n~s. The prosthes~s ~s then sutured about the valve annulus to posit~on each flexible ~olnt ad~acent to the area of the valve at ~h k h the cusps overlap. The same degree of flcx~b~lity can also be ach~eved for a tr kusp~d val~e by the ; use of at least three segment, which are appropriately ~o~ned together.
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In accordance w~th one embod~ment the ring prosthes~s ~ncludes a generally r~g~d segment form~ng a substant~al port~on of the r~ng prosthesis. The remainder of the r~ng prosthes~s ls formed frGm small segments. These small segments are l~nked together by a flex~ble cord, wh kh ~n comblnat~on w~th the size of the segments prov~des for a very flexible port~on of the r~ng prosthes~s. Th~s portlon of the r~ng prosthes~s would be pos~t~oned ad~acent to the poster~or cusp of a m~tral valve. It ls thus ev~dent at a r~ng prosthesis of the lnvention can be des~gned to prov~de for flex~b~lity along desired locat~ons of the valve annulus.

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g ` The present invention will be described in greater detail with - reference to F;gures 1 and 2. One embodiment of a r~ng -~ prosthesis of the inventlon ~s seen generally ~n F~gures 1 and 2 at 10. This ring prosthesis 10 is that embod~ment ~n wh~ch the ~ major portion of the ring will be formed from a substant~ally -. 5 rigid segment, with the remainder of the ring prosthes~s be~ng composed of a plurality of smaller segments.
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In particular, ring prosthesis 10 ~ncludes a f~rst substantlally rigid segment 12 which defines the ma~ority of the circumference of the r~ng prosthesis 10. Specif~cally, segment 12 ~s a - substantially c~rcular shaped opened r~ng sized to proportlonally fit about a substantial port~on of the annulus of the part~cular heart valve. In part~cular, segment 12 ~s formed to fit around about 1/2 to about 2~3 of the c~rcumference of the particular heart valve annulus.
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By the segment t2 be~ng termed as substantlally r~gld ~t ls ~eant that the ends of the segment 12, seen generally at 16 and 18> may be deflected towards each other by the appl~cation of force~ The amount of flex~ng is dependent upon the mater~al ~ fr~m wh k h the segment ~s formed, and the s~ze of the segment.
¦ The flex~b~l~ty may be measured by e~ther calculat~ng or i d~rectly measurlng the spr~ng rate for the r~ng prosthesls segment 12, as determ~ned by apply~ng the force aga~nst the ends lC and 18. The lower the flexlb~llty, the greater the ~ flexlb~l~ty of the segment 12.
i Th~s sprlng rate may be calculated by the concept known as F~nite Element Analys~s. This concept ~nvolves calculat~ng the spr~ng rate by knowing the mater~al from whlch the segment 12 ~s formed and also the dlmens~ons of the segment 12. For a more deta~led discuss of thls concept see, "Concept and Appl k at~ons ':
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of Fin~te Element Analysis~, Second Edit~on, Robert D. Cook, Department of Engineering Mechanics, Univers~ty of Wisconsin-Madison, John Wiley & Sons, 1981. The smaller the segment 12, and thus the smaller the prosthesis, the ~reater the degree of the flexibility for the r;ng prosthesls. For example, a ring prothesis of 26 millimeters would have a r~ng spr~ng rate of 310 grams per mlllimeter, while a r~ng prosthesls of 38 mlll~meters would have a r~ng sprlng rate of 452 grams per m~llimeter.

As seen ~n Figure 1, segment 12, wh~ch has a generally crescent shape, ~ncludes a first substantially stra~ght section 14, and two curv~ng end portions 16 and 18. The stra~ght sect~on 14 ls usually d~mensioned to f~t along the base of the anter~or cusp of an associated b~leaflet heart valve, wh~ch ~s seen generally ~n phantom ~n Fig. 1 at 30, or along the base of the median cusp ~ of a tr~leaflet heart valve, not shown. The end portlons 16 and i~ 18 are curved to f~t about the heart valve annulus.

The segment 12 ~s preferably tapered ~n the d~rect~on of the end port~ons 16 and 18. Th~s taper~ng ~ncreases the overall flex~blllty of the segment 12, or more prec~sely provldes a lo~er spr~ng rate.

~ The r~ng prothes~s lU further ~ncludes a multisegmented sectlon 25 32 formed from a plural~ty of lnd~v~dual segments, two of whlch ` are seen generally at 24 and 26. These segments 24 and 26 are arranged in an end to end relat~onshtp between the ends of the segment 12. These segments 24 and 26 are l~nked together by at least one thread 28. As w~ll be d~scussed more fully here~n, thls thread 28 ~s alternat~vely laced through appropr~ately poslt~oned holes ln each of the segments 24 and 26, and t~ed off ~n the last two of these segments.

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While the indiv~dual segments 24 and 26 are generally cylindrk al ln shape, it is preferen~lal to form the ends of adjacently positioned segments 24 and 26 with complementary --~ shaped ends. This provldes for a snug fit between such segments, while allowing for a degree of flex~b~l~ty. For example, as seen in Figures 1 and 2, the segments 24 are formed ~th round concave depress~ons, one of which ts seen at 20, ~nto wh~ch fit a complementary formed rounded end, one of which 1s seen at 22, of the ad~acent segment 26. The arrangement of the - ind~vidual segments 24 and 26 ~n an end to end relat~onsh~p, and linked together by the thread 28, forms the mult~segmented section 32 wh~ch fits between the ends 16 and 18 of segment 12.
The mult~segmented sect~on 32 is generally flex~ble at the ~unct~on of the ~nd~v~dual segments 24 and 26, wlth the overall flex~b~lity of the sect~on 32 controlled by the number and dimens~ontng of the lnd~v~dual segments 24 and 26.

The tying of the segment 24 and 26 together ma~nta~ns the ~ntegr~ty of this mult~segmented sect~on 32. In order to effect the ty~ng of the individual segments 24 and 26 together, each segment ~s formed w~th a slngle hole 40, generally pos~tloned at the m~d-po~nt of the lnd~v~dual segment. The thread 28 ls sequent~ally laced through the holes 40 of ad~acently poslt~oned segments. The thread 28 is then t~ed off at one of the end segments~ one of wh kh ~s seen as segment 26 ~n F~gure 2.

Alternatively, s~ngle threads, not shown, may be used to tie together ad~acent ones of the segments 24 and 26. Any other means of form~ng a s~mllar type of multlsegmented sect~on ls sultable for the purpose of the ~nvent~on.

As stated, the r~ng prosthes~s of the lnvention further ~ncludes hlnged ~o~nts between the ~ndivldual segments. In the -- 1~

lllustrated embodiment, the multisegmented section 32 functions as a single segment, with the hinged joints being formed between this section 32 and the segment 12. The h~nged ~o~nts are formed by a cloth covering 34 ~rapped substant~ally t~ght about the segment 12 and section 32, with the coverlng belng plnched together between the adjacent ends of the sect~on 32 and segment 12. As illustrated the cover is plnched together by tightly -~ tying a str~ng about the cover 34 at these locat~ons, w~th such < tied strings being seen at 36 and 38. The cover 34 not only ma~ntains the positioning of the section 32 between the ends of 10 segment 12, but also pro~des a site for sutur~ng the r~ng ~ prosthes~s about the valve annulus~
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The flexlble ~o~nts formed between the ends of the sect~on 32 and segment 12 prov~des a degree of flex~b~l~ty. Furthermore, 15 the format~on of the sectlon 32 from the plurallty of the ~nd~vldual segments 24 and 26 enhances the flex~b~llty of the ring prosthes~s at th~s locat~on. By the approprlate dimensionlng of the segment 12, and the ~ndlvidual segments 24 and 26, the overall flex~b~lity and r~g~dlty of the prosthes~s ~; 20 12 may be man~pulated.
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Th~ segments 12, 24 and 26 may be formed from any su~table and b~ologlcally eompatlble mater~al. Preferent~ally, the segment 12 ~s formed from t~tan~um, ~h11e the lndl~ldual segments 24 and 25 26 are formed from a plastlc mater~al, and pre~erably a ~ rad~opaque plasff c, e.g. Delr~n , w~th barlum sulfate f~ller.

I Referr~ng no~ to Flgure 3, a r~ng prosthesis ~n accordance w1th ~, another embod~ment of the lnvent~on ls seen generally at 50.
Rlng prosthesls 50 ~ncludes three segments 52, 54 and 56.
Segment 56 ls a substantially straight member, d~mensioned to flt around from about 1/3 to about 1l2 of the circumference of the assoc~ated heart valve annulus. The two segments 52 and 54 -~-. ~, Ar " ,, ,, ,:, 1; " ,, "" ";,," ,, " , ,, , ,"",, , ;, , "~ ", are curved members of substantially equal length and pos~t~oned between the ends of segment 56. These three segments 52, 54 and 56 are held in position with respect to each other by a cloth covering 62, tightly wrapped about the segments 52, 54 and 56 ~n a manner similar to the embodiment d~scussed above.
Furthermore, ties 64, 66 and 68 are tightly drawn about the cloth covering 62 at respective locations between the ad~acently positioned segments 52, 54 and 56. Thls forms three h~nged joints between the segments 52, 54 and 5~.
, The illustrated ring prosthesis 50 having three segments ls part~cular useful for placement about a tr~leaflet heart valve.
The larger and substant~ally stra~ght segment 56 ls pos~t~oned ad~acent to the median cusp of the heart valve, wh~le the rema~ning smaller but equilvalently s~zed segments 52 and 54 are usually arranged ad~acent to the anter~or and poster~or cusps of the heart valve.

j In accordance w~th a still further embod~ment, not shown, of the invent~on, a ring prosthes~s ls formed from two, substant~ally e~u~valent segments~ This embodiment is part~cularly useful wlth a b~leaflet heart valve, w~th the r~ng arranjqed about the base of the heart valve to position each of the segment ad~acent to the anterlor and poster~or cusps.

Wh~le the preferred embod~ments have been described, var~ous modilf~caff ons and substitut~ons may be made thereto w~thout departlng from the scope of the ~nvention~ According1y, it is to be understood that the ~nvent~on has been described by way of ~llustrat~on and not l~m~tatlon.

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Claims

1. An annuloplasty ring prosthesis comprising:
a body which defines a substantially circular shaped ring proportioned to fit about the annulus of a heart valve, said body being formed from two or more segments, each of which is formed with opposing ends;
a flexible covering fitted about said segments to position each of said segments ends adjacent to an end of another of said segments, with said ends remaining unconnected; and means associated with said covering for snugly holding said covering about said adjacently positioned ends.

2. The annuloplasty ring prosthesis of claim 1 wherein said individual segments are substantially rigid.

3. The annuloplasty ring prosthesis of claim 1 wherein said body is formed from three substantially equivalently sized and shaped segments.

4. The annuloplasty ring prosthesis of claim 1 wherein at least one of said segments is formed from a plurality of individual smaller elements linked together.

5. The annuloplasty ring prosthesis of claim 1 including two of said segments wherein one of said segments is substantially straight with slightly curved ends, and said second of said segments is formed from a plurality of individual smaller linked together elements.

6. The annuloplasty ring prosthesis of claim 5 wherein said smaller elements are tied together with a cord.

7. The annuloplasty ring prosthesis of claim 6 wherein each of said elements are formed with at least a first aperture through which said cord is drawn.

8. The annuloplasty ring prosthesis of claim 1 wherein said holding of said covering about said adjacently positioned segment ends is obtained by tightening said covering between said adjacent segment ends.

9. The annuloplasty ring prosthesis of claim 8 wherein said ring prosthesis includes two segments.

10. The annuloplasty ring prosthesis of claim 8 wherein said ring prosthesis includes three segments.

11. The annuloplasty ring prosthesis of claim 10 wherein a first of said segments is substantially straight, with said two other of said segments being curved.

12. The annuloplasty ring prosthesis of claim 8 wherein said ring prosthesis includes a first substantially straight segment having curved ends and a second segment formed from a plurality of linked together elements positioned between said curved ends of said first segment.

13. The annuloplasty ring prosthesis of claim 12 wherein said first segment is formed from titanium and said second segment is formed from a plastic material.

14. The annuloplasty ring prosthesis of claim 2 wherein said holding of said segment ends is obtained by tightening said covering between said adjacent segment ends.

15. The annuloplasty ring prosthesis of claim 4 wherein said holding of said segment ends is obtained by tightening said covering between said adjacent segment ends.

16. The annuloplasty ring prosthesis of claim 5 wherein said holding of said segment ends is obtained by tightening said covering between said adjacent segment ends.

17. The annuloplasty ring prosthesis of claim 16 wherein said individual elements forming said segment are oblong bodies arranged in an end to end relationship, with alternating ones of said bodies being formed with circular ends and said remaining ones of said bodies being formed with concave ends for receiving said circular element ends.