United States Patent [19J
`Nguyen et al.
`
`[54] MULTI-LEAFLET BIOPROSTHETIC HEART
`VALVE
`
`[75]
`
`Inventors: Than Nguyen, Anaheim; Hung Ly
`Lam, Norco; Jianbo Zhou, Irvine;
`Carlos M. Romero, Orange; Ralph
`Kafesjian, Newport Beach; Xiaoming
`G. Guo, Dove Canyon; Van Le Huynh,
`Tustin, all of Calif.
`
`[73] Assignee: Baxter International Inc., Deerfield,
`Ill.
`
`[21] Appl. No.: 08/833,176
`
`[22] Filed:
`
`Apr. 3, 1997
`
`Int. Cl.6
`........................................................ A61F 2/24
`[51]
`[52] U.S. Cl. ................................................. 623/2; 623/900
`[58] Field of Search ................................ 623/1, 2, 11, 12,
`623/66, 13, 900
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,388,735
`4,687,483
`5,037,434
`5,376,110
`5,549,666
`5,613,982
`5,718,012
`
`6/1983 Ionescu et al. .
`8/1987 Fisher et al. .
`8/1991 Lane ............................................ 623/2
`12/1994 Tu et al.
`................................... 623/12
`8/1996 Hata et al. ................................ 623/11
`3/1997 Goldstein .................................. 623/66
`2/1998 Cavallaro .................................. 623/11
`
`FOREIGN PATENT DOCUMENTS
`
`0133420
`
`2/1985 European Pat. Off ..
`
`OIBER PUBLICATIONS
`
`Sacks, "Biaxial Mechanical Behavior of Fixed Bovine Peri(cid:173)
`cardium", Fifth World Biomaterials Congress, Toronto,
`Canada, May 29-Jun. 2, 1996.
`
`I 1111111111111111 11111 111111111111111 1111111111 1111111111111111 Ill lllll llll
`US005961549A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,961,549
`Oct. 5, 1999
`
`Simionescu, et al., "Mapping of Glutaraldehyde-Treated
`Bovine Pericardium and Tissue Selection for Bioprosthetic
`Heart Valves", Journal of Biomedical Materials Research,
`vol. 27, 697-706, 1993.
`Zioupus, et al., "Anisotropic Elasticity and Strength of
`Glutaraldehyde Fixed Bovine Pericadium for Use in Peri(cid:173)
`cardia! Bioprosthetic Valves", Journal of Biomedical Mate(cid:173)
`rials Research, vol. 28, 49-57, 1994.
`Primary Examiner-Mickey Yu
`Assistant Examiner-Francis K. Cuddihy
`Attorney, Agent, or Firm-Guy L. Cumberbatch
`ABSTRACT
`[57]
`
`Heart valve leaflet selection methods and apparatuses which
`subject individual leaflets to loads and measure the resulting
`deflection to more reliably group leaflets of similar physical
`characteristics for later assembly in prosthetic heart valves.
`The deflection testing may be accomplished using a variety
`of test set ups which are designed to impart a load on the
`leaflet which simulates the actual loading within a heart
`valve. The results from a number of deflection tests are used
`to categorize individual leaflets, which data can be com(cid:173)
`bined with other data regarding the characteristics of the
`leaflet to better select leaflets for assembly into a multi(cid:173)
`leaflet heart valve. In one embodiment, the deflection test is
`combined with an intrinsic load test, and leaflets having
`similar deflection and intrinsic load values used in the same
`heart valve. One apparatus for testing the leaflets includes a
`frame for securing the arcuate cusp of the leaflet while the
`straight coapting edge remains free, to simulate the actual
`leaflet mounting configuration within the heart valve pros(cid:173)
`thesis. The frame may include a lower portion having a
`recess for the leaflet and plurality of receptor holes around
`the peripheral edge of the recess, and an upper portion
`having a plurality of needles which extend downward
`through the leaflet and into the receptor holes and secure the
`edges of the leaflet.
`
`15 Claims, 9 Drawing Sheets
`
`NUMBER
`25
`
`20
`
`15
`
`10
`
`5
`
`0
`
`N
`0
`
`If)
`N
`0
`
`DEFLECTION VALUE
`
`Edwards Lifesciences Corporation, et al. Exhibit 1020, p. 1 of 19
`
`

`

`U.S. Patent
`
`Oct. 5, 1999
`
`Sheet 1 of 9
`
`5,961,549
`
`5 4-:x--(cid:173)
`Q
`'--·-
`
`38
`
`44-v
`I
`
`34
`
`FIG. 1
`
`Edwards Lifesciences Corporation, et al. Exhibit 1020, p. 2 of 19
`
`

`

`U.S. Patent
`
`Oct. 5, 1999
`
`Sheet 2 of 9
`
`5,961,549
`
`38
`
`20
`
`~
`
`~ 2 6
`
`68 70
`74
`
`FIG. 2
`
`Edwards Lifesciences Corporation, et al. Exhibit 1020, p. 3 of 19
`
`

`

`u.s. vatent
`
`oct. 5, 1999
`
`sneet 3 of 9
`
`5,961,549
`
`98
`
`102
`
`f\G. 4
`
`96
`
`118
`
`Edwards Lifesciences Corporation, et al. Exhibit 1020, p. 4 of 19
`
`

`

`U.S. Patent
`
`Oct. 5, 1999
`
`Sheet 4 of 9
`
`5,961,549
`
`FIG.5
`
`/JO
`126~
`
`/34
`
`128
`
`IJ2
`
`FIG.7
`
`.96
`
`110.
`
`/,10
`
`128
`
`Edwards Lifesciences Corporation, et al. Exhibit 1020, p. 5 of 19
`
`

`

`U.S. Patent
`
`Oct. 5, 1999
`
`Sheet 5 of 9
`
`5,961,549
`
`FIG. 6
`
`//,I
`
`FIG. 6a
`
`126'
`
`~
`
`·---1'3+
`
`l+O
`
`Edwards Lifesciences Corporation, et al. Exhibit 1020, p. 6 of 19
`
`

`

`U.S. Patent
`
`Oct. 5, 1999
`
`Sheet 6 of 9
`
`5,961,549
`
`FIG.Ba
`
`56
`
`g,1
`
`52
`
`JO
`
`FIG.Sb
`
`56
`
`g,1
`...
`
`52
`
`JO
`
`d
`
`/24-
`
`//,I
`
`22.
`
`//,I
`
`22
`
`Edwards Lifesciences Corporation, et al. Exhibit 1020, p. 7 of 19
`
`

`

`U.S. Patent
`
`Oct. 5, 1999
`
`Sheet 7 of 9
`
`5,961,549
`
`NUMBER
`25
`
`20
`
`15
`
`10
`
`5
`
`0
`
`N
`0
`
`-.,,
`
`0
`
`.,, .,, .
`
`0
`
`Lt") .,,
`
`0
`
`DEFLECTION VALUE
`
`FIG.9
`
`Edwards Lifesciences Corporation, et al. Exhibit 1020, p. 8 of 19
`
`

`

`U.S. Patent
`
`Oct. 5, 1999
`
`Sheet 8 of 9
`
`5,961,549
`
`FIG.JOA
`14
`12
`10
`8
`6
`4
`2
`0 O')
`
`0:::
`L&J m
`:I:
`::,
`z
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`FIG.IDB
`12
`10
`8
`0::: 6
`L&J m
`:I: 4
`::,
`z
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`.
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`0
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`L&J
`CD 2
`:I:
`::,
`z
`1
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`.....
`N
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`..,.,
`N .
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`0
`
`.
`
`,....
`II)
`O')
`.
`N
`N
`N
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`0
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`DEFLECTION VALUE
`
`.
`
`DROOP B CATEGORY
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`..,.,
`N .
`
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`.
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`N
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`
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`
`..,.,
`0
`
`Edwards Lifesciences Corporation, et al. Exhibit 1020, p. 9 of 19
`
`

`

`U.S. Patent
`
`Oct. 5, 1999
`
`Sheet 9 of 9
`
`5,961,549
`
`..,,
`
`0
`
`N
`0
`
`0
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`z
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`
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`•
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`
`Edwards Lifesciences Corporation, et al. Exhibit 1020, p. 10 of 19
`
`

`

`5,961,549
`
`1
`MULTI-LEAFLET BIOPROSTHETIC HEART
`VALVE
`
`FIELD OF THE INVENTION
`
`The present invention relates to methods for selecting
`leaflets for use in a prosthetic heart valve, and, more
`particularly, to methods and apparatuses for selecting indi(cid:173)
`vidual pericardia! leaflets for a multi-leaflet heart valve
`pro thesis.
`
`BACKGROUND OF THE INVENTION
`
`Prosthetic heart valves are used to replace damaged or
`diseased heart valves. In vertebrate animals, the heart is a
`hollow muscular organ having four pumping chambers: the
`left and right atria and the left and right ventricles, each
`provided with its own one-way valve. The natural heart
`valves are identified as the aortic, mitral ( or bicuspid),
`tricuspid, and pulmonary valves. Prosthetic heart valves can
`be used to replace any of these natural valves. The two
`primary types of prosthetic heart valves known in the art are
`mechanical valves and bio-prosthetic valves. Mechanical
`valves include rigid leaflets and a pivoting mechanism, and
`bio-prosthetic valves utilize flexible tissue leaflets, typically
`mounted to a manufactured support frame. The present
`invention provides methods for selecting leaflets in bio(cid:173)
`prosthetic valves.
`Bio-prosthetic valves may be formed from an intact,
`multi-leaflet porcine (pig) heart valve, or by shaping a
`plurality of individual leaflets out of bovine pericardia!
`tissue and combining the leaflets to form the valve. The
`pericardium is a sac around the heart of vertebrate animals,
`and bovine (cow) pericardium is commonly used to make
`individual leaflets for prosthetic heart valves. The bovine
`pericardium is first harvested from the animal and then
`chemically fixed to crosslink collagen and elastin molecules
`in the tissue and increase the tissue durability, before being
`cut into leaflets. Various physical characteristics of the tissue
`may be examined before or after fixation.
`One drawback faced by a patient having an implanted 40
`bio-prosthetic heart valve is the potential for calcification of
`the leaflets if the valve remains in place for an extended
`period of time (more than ten years). Calcification tends to
`make the leaflets less flexible. A significant amount of
`research has been accomplished in mitigating calcification 45
`of bovine pericardia! leaflets to lengthen the useable life of
`the heart valve. Calcification may reduce the performance of
`the heart valve, and thus, the highest quality materials and
`design in the heart valve is required to forestall a failure of
`the valve from excessive calcium deposits.
`Despite the drawbacks of artificial heart valve material,
`over twenty years of clinical experience surrounding
`implanted artificial heart valves has produced a proven track
`record of success. Research in extending the useful life of
`the bio-prosthetic valves continues, however. One aspect of 55
`designing heart valves which is very important in improving
`their performance is the selection of the pericardia! tissue
`used in the leaflets. In all heart valves, the natural action of
`the flexible heart valve leaflets, which seal against each
`other, or co-apt, is desirable. The difficulty in simulating the 60
`leaflet movement of an actual heart valve ( especially a mitral
`valve) in a prosthetic valve is that the leaflets used are
`"inanimate." There are no muscular attachments to the
`leaflets as in the natural valve, and the prosthetic leaflets
`must co-apt to function properly solely in response to the 65
`fluid pressures within the heart chambers. Indeed, natural
`coaptation of the leaflets in bio-prosthetic valves comprising
`
`2
`a plurality of individual leaflets sewn together is particularly
`difficult, even when compared to inanimate but intact valves,
`such as harvested porcine valves.
`Much of this research involves the mechanical properties
`5 of fresh or fixed bovine pericardium. A good discussion of
`the various physical properties of fixed bovine pericardium
`is given in Simionescu, et al, Mapping of Glutaraldehyde(cid:173)
`Treated Bovine Pericardium and Tissue Selection For Bio(cid:173)
`prosthetic Heart Valves, Journal of Bio-Medical Materials
`10 Research, Vol. 27, 1993. Simionescu, et al, recognized the
`sometimes striking variations in physical properties of the
`pericardia! tissue, even in the same pericardia! sac. Their
`research mapped out areas in individual pericardia! sacs and
`tested those areas for fiber orientation, suture holding power,
`15 and thickness. In another paper by Sacks, Bi-axial Mechani(cid:173)
`cal Behavior of Fixed Bovine Pericardium, Fifth World
`Biomaterials Congress, May-June 1996, the collagen fiber
`architecture within bovine pericardia! tissue was examined
`and various specimens were tested in a bi-axial tester. The
`20 results indicated that by presorting for uniform collagen
`fiber architecture, more uniform bio-pericardial specimens
`could be obtained for better controlled use in bioprosthetic
`applications. Finally, in another study, Zioupos, et al,Aniso(cid:173)
`tropic Elasticity and Strength of Glutaraldehyde Fixed
`25 Bovine Pericardium For Use In Pericardia! Bioprosthetic
`Valves, Journal of Biomedical Materials Research, Vol. 28,
`1994, various tests were performed on fixed bovine pericar(cid:173)
`dia! tissue to determine the stress/strain behavior along
`various axes. The results suggest that leaflets can be made
`30 from fixed bovine pericardium possessing pronounced
`anisotropy in strength and stiffness along two orthogonal
`directions. In the leaflets circumferential direction, which
`bears most of the stress during function, the stiffer pericar(cid:173)
`dium is desired, while in the radial direction, more flexible
`35 tissue is desired. Leaflets are thus cut from bulk tissue whose
`properties have generally been examined, and the leaflets
`categorized accordingly.
`Despite the extensive research into bulk tissue character(cid:173)
`istics there remains a need for a more reliable method of
`selecting leaflets to insure maximum functional compatibil(cid:173)
`ity with the other leaflets in the dynamic operating environ(cid:173)
`ment of a prosthetic heart valve.
`
`SUMMARY OF THE INVENTION
`
`The present invention provides methods and apparatuses
`for selecting leaflets for use in producing multi-leaflet pros(cid:173)
`thetic heart valves. The selection of leaflets to be combined
`in a heart valve is based on grouping a plurality of leaflets
`50 by strain response to an applied load which is designed to
`simulate physiological pressures within the heart. A stress
`load sufficient to stress the leaflets within a high modulus
`region of their stress/strain characteristic is applied to each
`leaflet, and leaflets within a predetermined observed deflec(cid:173)
`tion range of each other are grouped together. In an exem(cid:173)
`plary embodiment, glutaraldehyde-fixed leaflets are stressed
`within a generally linear, high modulus region of the bulk
`tissue stress/strain curve, and the deflection measured for
`grouping the leaflets. In one embodiment, the strain response
`is observed relative to a deflection of bovine pericardium
`leaflets resulting from applying a load thereto, and two or
`three leaflets from a group of leaflets having deflections
`within 0.030 inches of each other are combined to form a
`prosthetic heart valve.
`One aspect of the present invention is a method of
`selecting leaflets for an implantable heart valve, including
`providing a collection of similarly sized leaflets, applying a
`
`Edwards Lifesciences Corporation, et al. Exhibit 1020, p. 11 of 19
`
`

`

`5,961,549
`
`3
`load to each leaflet, observing the resulting strain response,
`and sorting the leaflets based on their respective strain
`responses. The collection may be natural tissue leaflets
`which are chemically fixed prior to testing. The natural
`tissue leaflets may be made of bovine pericardium. In one
`embodiment, the load applied is sufficient to create an
`average stress in at least some of the leaflets of between 300
`and 600 kPa. The load is preferably applied for a predeter(cid:173)
`mined number of times prior to observing the strain
`response. Another aspect of the invention is a bioprosthetic
`heart valve manufactured with leaflets selected by the afore(cid:173)
`mentioned method, wherein the number of leaflets selected
`may be three.
`The present invention also provides a method of testing a
`leaflet for use in an implantable heart valve, including
`mounting the leaflet in a frame so that portions which are to
`be sutured in the valve are held stationary. A load is applied
`to the leaflet in a location adapted to simulate a point at
`which an average load is applied in the valve, and the
`resulting strain in the leaflet is sensed. The natural tissue
`leaflet typically defines a cusp and a coapting edge generally
`opposite the cusp, and the step of mounting may comprise
`holding stationary at least the cusp of the leaflet. The leaflet
`may be positioned in a framing assembly having a recess for
`receiving at least the edges of the cusps of the leaflet, and a
`cavity circumscribed by the recess. Moreover, the load may
`be applied by a mechanical deflector to an upper surface of
`the leaflet over the cavity. Preferably, the framing assembly
`includes an upper member and a lower member, the lower
`member having the recess and the upper member shaped to
`mate over the recess. The method further includes piercing 30
`the leaflet edges with needles extending between and sup(cid:173)
`ported from movement by the upper and lower members.
`The present invention provides an apparatus for testing
`heart valve leaflets having a leaflet framing assembly includ(cid:173)
`ing a holder with a recess for receiving a leaflet to be tested
`and a frame which cooperates with the holder to hold
`stationary the cusps of the leaflet. The apparatus includes a
`base having indexing structure for locating the framing
`assembly thereon, and a deflection assembly indexed with
`respect to the base and having a deflector mounted for
`movement above the framing assembly to contact the leaflet.
`The recess may be cusp-shaped, and the holder includes a
`cavity substantially surrounded by the recess over which the
`leaflet is suspended. The apparatus may further include
`structure adapted to hold stationary discrete points of the
`leaflet around the cavity. To secure discrete points of the
`leaflet around the cavity, the frame preferably includes a
`plurality of needles having their pointed ends downward,
`and the recess includes receptor holes for the needles,
`wherein the cusp of the leaflet is secured against movement
`at the discrete points defined by the needles.
`
`25
`
`4
`FIG. 6a is a top elevational view of the leaflet holder, with
`leaflet therein, taken along line 6a-6a of FIG. 6;
`FIG. 7 is an assembled perspective view of a leaflet
`framing assembly comprising the leaflet mounting frame,
`5 and leaflet holder;
`FIG. Sa is an elevational view of a deflector in contact
`with a leaflet to be tested and mounted within the framing
`assembly prior to a deflection test;
`FIG. Sb is a front elevational view of the framing assem-
`10 bly with a leaflet support removed and the deflector deflect(cid:173)
`ing a leaflet;
`FIG. 9 is a graph showing tissue deflection values for a
`plurality of 29 mm CEP mitral valve leaflets;
`FIG. 10a is a graph showing a distribution of deflection
`15 values for a number of leaflets which have been previously
`grouped and categorized by droop characteristic, Category
`A;
`FIG. 10b is a graph showing a distribution of deflection
`values for a number of leaflets which have been previously
`20 grouped and categorized by droop characteristic, Category
`B;
`FIG. 10c is a graph showing a distribution of deflection
`values for a number of leaflets which have been previously
`grouped and categorized by droop characteristic, Category
`C.; and
`FIG. 11 is a graph illustrating a typical stress-strain curve
`for pericardia! tissue.
`DESCRIPTION OF THE EXEMPLARY
`EMBODIMENTS
`The present invention involves testing individual leaflets
`for use in producing heart valves which, in its broadest
`sense, provides methods and apparatuses for obtaining and
`grouping the deflection response of individual leaflets in
`order to better sort or group them for later selection and
`35 combining with other leaflets to form a valve. Unlike prior
`art bulk tissue testing, the present invention characterizes
`individual leaflet response under loads similar to those the
`leaflets are subjected to under normal physiological condi(cid:173)
`tions within the heart. Not only are the loads higher than
`40 previously used in tissue testing, but the leaflets are sub(cid:173)
`jected to repeated loadings, which conditions the leaflet
`tissue, prior to observing a deflection. Although the bulk
`mechanical properties of tissue in general have been studied,
`prior art non-destructive tests of individual tissues already
`45 cut to leaflet shape have not been developed or utilized to
`group tissue leaflets for assembly into prosthetic valves.
`An exemplary deflection testing apparatus, disclosed
`within the teachings of the present invention, closely simu(cid:173)
`lates dynamic pressure on the individual leaflets with a
`50 mechanical deflector having a smooth, generally spherical
`tip on the end for repeatedly contacting a framed and
`supported leaflet at a pre-determined contact location. The
`leaflet is framed and secured around its periphery at a
`number of discrete points designed to simulate the lines of
`55 suturing that would retain the leaflet within an actual pros(cid:173)
`thetic heart valve. The invention should not be limited to the
`specific apparatus shown, however, and is intended to cover
`any equivalent apparatuses or methods which take indi(cid:173)
`vidual leaflets and subject them to loading while measuring
`60 their deflection response. For example, an alternative appa(cid:173)
`ratus contemplated as being within the scope of the present
`invention may apply a pressure to the leaflet, as opposed to
`a discrete or diffuse mechanical load.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a front perspective view of an exemplary leaflet
`tester illustrating the principles of the present invention;
`FIG. 2 is a rear perspective view of the leaflet tester of
`FIG. 1;
`FIG. 3 is a perspective view of a leaflet mounting frame
`for use in the leaflet tester;
`FIG. 4 is an exploded perspective view of the leaflet
`mounting frame and a needle calibration gauge for use
`therewith;
`FIG. 5 is a perspective view of an exemplary leaflet holder
`for use in the leaflet tester;
`FIG. 6 is an exploded perspective view of the leaflet 65
`mounting frame over the leaflet holder, with a leaflet held
`therein;
`
`Exemplary Deflection Tester Apparatus
`One particular embodiment of a leaflet deflection tester 20
`for loading individual leaflets is shown in FIGS. 1 and 2.
`
`Edwards Lifesciences Corporation, et al. Exhibit 1020, p. 12 of 19
`
`

`

`5,961,549
`
`5
`Referring to FIG. 1, the leaflet deflection tester 20 comprises
`a flat base 22 supporting a leaflet framing assembly 24 and
`a deflector assembly 26 thereabove. A leaflet 28 is shown
`mounted within the framing assembly 24 and a deflector 30
`is positioned to apply a load to the leaflet to result in a
`deflection which can be read from display 32. For purposes
`of discussion, the display 2 faces in a forward longitudinal
`direction, and lateral left and right directions are defined
`from the perspective of looking at the display.
`The deflector assembly 26 comprises a support post 34
`vertically oriented with respect to the base 22 and attached
`thereto with a post holder 36. Referring to FIG. 2, at the top
`of the post 34, a cap 38 is vertically adjustable via a set screw
`40 engaging a vertical groove 42 in one side of the post. An
`indicator carriage 44 is also vertically adjustable along the
`post and may be secured at various locations using a pair of
`carriage locking screws 46 which also engage the groove 42.
`A carriage arm 48 extends longitudinally forward from the
`post 34 and terminates in a position indicator 50 mounted
`thereto. Referring to FIG. 1, the position indicator preferably
`includes electronic circuitry and a digital readout 32, but
`may be of a variety of configurations, and the particular
`embodiment illustrated herein should not be construed as
`limiting. Control buttons 51 including a zero reset function
`are provided on the face of the indicator 50.
`The position indicator 50 is generally centrally located
`above the leaflet framing assembly 24 and includes an
`indicator shaft 52, vertically passing therethrough and
`engaging position-sensing equipment within the indicator.
`That is various known mechanical or electro-mechanical
`device; for sensing the displacement of a shaft within a
`housing are contemplated for this purpose and will not be
`described further herein. A mass 54 attaches to an upper end
`of the indicator 52 above the position indicator 50. At the
`lower end of the shaft 52, a collar 56 is fastened thereon via
`a locking screw 58. The collar continues downward and
`terminates in the aforementioned deflector 30.
`The deflector assembly 26 further includes a means for
`vertically adjusting the position between the post cap 38 and
`the indicator carriage 44. A vertical adjustment knob 60 is
`mounted for rotation above a vertical axis through the post
`cap 38. The adjustment knob 60 engages a connecting rod 62
`which extends between the post cap 38 and the indicator
`carriage 44. In one embodiment, the vertical adjustment
`knob 60 rotates a threaded nut within the post cap 38 which
`engages male threads on an upper end of the connecting rod
`60 to cause its vertical displacement. The connecting rod 62
`is preferably firmly connected to the indicator carriage 44
`and thus turning the vertical knob 60 vertically displaces the
`indicator carriage 44. The use of the vertical adjustment
`knob 60 in calibrating and operating the tester 20 will be
`described below.
`With reference still to FIG. 1, and, more particularly, to
`the rear perspective view in FIG. 2, the post holder 36 is
`formed as a monolithic T-shaped block, having a pair of
`overhanging edges through which longitudinally oriented
`adjustment slots 68 are provided. The slots 68 are provided
`on either lateral side of the support post 34 and receive
`locking bolts 70 which extend downward into engagement
`with a step 72 formed in a longitudinal adjustment bracket
`74. The longitudinal adjustment bracket 74 can thus be
`adjusted longitudinally with respect to the post holder 36
`and secured with the bolt 70.
`On a front end of the longitudinal adjustment bracket 74,
`an overhanging portion includes a lateral adjustment slot 76
`receiving a locking screw 78. Referring to FIG. 1, the
`
`10
`
`15
`
`6
`locking screw 78 continues through the overhanging portion
`of the adjustment bracket 74 into contact with a step 80
`formed in a lateral adjustment bracket 82 which is generally
`L-shaped, having a forwardly extending arm portion 84. An
`5 L-shaped clamp 86 is adjustable longitudinally with respect
`to the arm portion 84 and is fastened thereto with a pair of
`clamping screws 88. The combination of the adjustment
`brackets 74 and 82, and L-shaped clamp 86, index and
`secure the leaflet framing assembly 24 with respect to the
`support post 34 and, in turn, the position indicator 50.
`An upper framing assembly member or leaflet mounting
`frame 94, illustrated in FIGS. 3 and 4, comprises a generally
`rectangular shaped base 96, having an upper stepped recess
`98 open to a front side of the rectangle. An undercut 100 is
`formed in the recess 98 to receive a plate-shaped needle
`clamp 102 therein. The needle clamp 102 includes a semi-
`circular cutout 104 in an edge facing toward the open edge
`of the recess 98. The cutout 104 conforms to a semicircular
`cutout 106 formed in the base 96. It should be noted that
`20 although the cutouts 104, 106 are described as generally
`semicircular, the particular shape of the leaflet 28 may be
`somewhat oval in shape, which may correspondingly alter
`the shape of the cutouts.
`Both the base 96 and the needle clamp 102 include a
`25 plurality of registered, vertical through holes 108, arranged
`equidistantly around the semicircular cutouts 104 and 106.
`In a preferred embodiment, there are seven such through
`holes 108, arrayed at specific circumferential angles around
`the cutouts 104 and 106. The through holes 108 receive
`30 leaflet framing needles 110 which are vertically retained
`therein through the use of a needle clamp screw 112 threaded
`through a rear wall of the frame body 96 and into contact
`with the needle clamp 102.
`The frame base 96 further includes a plurality of posi-
`35 tioning tabs 114 depending downward therefrom. In the
`illustrated embodiment, there are three such tabs 114, two on
`left and right sides, respectively, of the frame base 96 and
`one on the rear side. With reference to FIG. 4, the tabs are
`utilized to orient a needle gauge or calibration member 116
`40 under the cutouts 104 and 106. More particularly, the needle
`gauge 116 comprises a generally rectangular base 118 and a
`recessed pocket 120. The base 118 is guided between the two
`side tabs 114 and abuts against the rear tab of the mounting
`frame 94. In this orientation, the pocket 120 is positioned
`45 directly below all of the through holes 108 so that the
`needles 110 depend downward below the lower surface of
`the frame base 96, as seen at 122, only as far as the pocket.
`The needles 110 are inserted through the holes 108 into
`contact with the pocket 120, and then the needle clamp
`50 screw 112 is tightened to push the needle clamp 102 in a
`direction out of the recess 98 and create a compression
`against the needles 110. That is, the shear force exerted on
`the needles 110 by the through holes 108 in the frame base
`96 and needle clamp 102 maintains the needles in the
`55 vertical position as calibrated by the needle gauge 116. Once
`the needles are calibrated to depend downward the same
`distance, the frame 94 is ready for use in the framing
`assembly 24.
`FIG. 5 illustrates a lower framing assembly member or
`60 leaflet holder 126 comprising a block-shaped body 128
`having a flat lower surface adapted to rest on the base 22
`(FIG. 1) and a flat upper platform 130. The body 128 is
`generally rectangular in shape and includes a rectangular
`base locator 132 projecting from a front side and shorter in
`65 height than the body 128. The outer edges of the body 128,
`other than the edge from which the base locator 132 extends,
`include positioning channels 134 opening to the platform
`
`Edwards Lifesciences Corporation, et al. Exhibit 1020, p. 13 of 19
`
`

`

`5,961,549
`
`7
`130. The positioning channels 134 receive the positioning
`tabs 114, previously described for the leaflet mounting frame
`94, as best seen in FIG. 6, to locate the mounting frame with
`respect to the leaflet holder 126. The lower surface of the
`leaflet mounting frame base 96 is flat and is juxtaposed with
`the flat platform 130. In the center of the body 128, and
`opening toward the base locator 132, a cavity 136 is formed
`having a generally semicylindrical shape. A stepped leaflet
`edge recess 138 is formed in the platform 130 surrounding
`the cavity 136 and is sized and shaped to receive a leaflet,
`such as the leaflet 28 as shown in FIGS. 1 and 2.
`Referring to FIG. 5, a paddle-shaped leaflet support 140
`has a generally semicircular end which fits closely within the
`cavity 136, with a handle 142 extending outward from the
`cavity 136 and resting on a top surface of the base locator
`132. The leaflet support 140 has a height which is identical
`to the height from the top surface of the base locator 132 to
`the elevation of the leaflet edge recess 138 so that the upper
`surface of the leaflet support 140 is in the same plane as the
`edge recess 138. The edge recess 138 further includes a
`plurality of needle receptor holes 144 sized and positioned
`in an array identical to the array in which the through holes
`108 and associated needles 110 are positioned around the
`leaflet mounting frame 94. This arrangement allows the
`needles 110 to extend through the peripheral edge of the
`leaflet 28 into the receptor holes 144, thus holding stationary
`portions of the leaflet at the edge recess 138.
`With reference to FIG. 6a, the leaflet typically includes a
`straight coapting edge 148 having opposed tab ends 150, and
`a generally semicircular cusp 152 therebetween and opposite
`the coapting edge. The tab ends 150 include angled sides 153
`transitioning to the coapting edge 148. The edge recess 138
`is sized and shaped to receive the cusp 152 and tabs 150 with
`the coapting edge 148 oriented parallel with but spaced from
`a front edge of the holder 126.
`FIG. 6a also illustrates a point 154 at which an axis
`through the center of the deflector 30 intersects the leaflet
`28. This point 154 will be referred to herein as the point of
`contact between the deflector 30 (FIG. 1) and leaflet 28, but
`in the exemplary embodiment the deflector is a relatively
`large diameter smooth hemisphere, and contacts the leaflet
`over a circular area to better simulate a distributed load and
`to help avoid stress risers. The point 154 is determined from
`a model of the stress distribution in the leaflet based on
`assumed forces applied to the leaflet in a human heart valve.
`The forces applied to the leaflet in a human heart valve
`originate from fluid pressures upstream and downstream of
`the valve, and the stress distribution is found from the
`leaflets' shape and boundary conditions (i.e., geometry of
`the lines of sutures attaching the leaflets in the valve). The 50
`point 154 is thus an idealized concentrated load point ( or
`concentrated area) equivalent to the actual distributed pres(cid:173)
`sure load.
`The leaflet is symmetrical about an axis perpendicular to
`and bisecting the coapting edge 148, and is typically con(cid:173)
`tinuously sutured in an actual valve along the cusp 152, and
`thus the point 154 is desirably on that axis. The dimension
`"A" is the distance from the point 154 to the coapting edge
`148 determined from the aforementioned stress distribution
`model. The dimension "A" will vary depending on the size
`and geometry of the leaflet, its thickness and bulk material
`properties, and the assumed