Ulllted States Patent [19]
`Shu et al.
`
`US006139575A
`[11] Patent Number:
`[45] Date of Patent:
`
`6,139,575
`Oct. 31, 2000
`
`[54] HYBRID MECHANICAL HEART VALVE
`PROSTHESIS
`
`5,562,729 10/1996 Purdy et al. .............................. .. 623/2
`5,569,463 10/1996 Helmus et al. ....................... .. 424/426
`
`[75] Inventors: Mark C. S. Shu, Mission Viego; Hong
`S- Shim, Santa Ana; Je?'rey M- Gross,
`Rancho Santa Margaarita, all of Calif.
`
`[73] Asslgnee' Medtromc’ Inc" Mmneapohs’ Mmn'
`[21] AppL NO‘: 09/286,095
`
`[22]
`
`Filed,
`
`Apt 2’ 1999
`
`FOREIGN PATENT DOCUMENTS
`WO 99/04731
`2/1999 WIPO ............................. .. A61F 2/24
`
`OTHER PUBLICATIONS
`The Return of Elastomer Valves (The Society of Thoracic
`Surgeons 1989,48.S98 9) William J. Kolff et al.
`
`Primary Examiner—D~avid J Isabella
`Attorney, Agent, or Fzrm—Harold R. Patton
`
`[51] Int. Cl.7 ...................................................... .. A61F 2/06
`[52] US. Cl. ................ ..
`623/2.12; 623/22
`
`[57]
`
`ABSTRACT
`
`of Search ................................... ..
`623/2-13, 214, 215, 216, 217, 219, 2-2
`
`[56]
`
`References Cited
`Us PATENT DOCUMENTS
`
`8/1968 Melrose -
`3,396,409
`3/1973 Cromie -
`377227004
`3,911,502 10/1975 Boretos ...................................... .. 3/15
`
`3/135
`7/1981 Hanson et a1‘
`4:276:658
`4,364,127 12/1982 Pierce et al. ............................... .. 3/15
`4,473,423
`9/1984 KOlff ..................................... .. 156/245
`4,510,628
`4/1985 Kolff _ _ _ _ _
`_ _ _ _ _ _ _ __ 3/15
`4,556,996 12/1985 Wallace ...... ..
`623/2
`4,643,732
`2/1987 Pietseh et a1~
`- 623/2-2
`477317075
`3/1988 Gallo et a1
`~~~~~ " 623/2
`571337845
`7/1992 Vallana
`' 204/1925
`
`A prosthetic mechanical heart Valve, and in particular, a
`bi-lea?et and/or a trilea?et mechanical valve formed With
`rigid frame and hinge elements for providing a stable
`reliable hinge mechanism With ?exible lea?ets formed of a
`thin elastomeric material adhering to and extending from the
`valve frame to form lea?et occluding sections bounded by
`outer peripheral edges for softening the opening and closing
`action of the valve lea?ets. In one embodiment, the valve
`lea?et is formed of a rigid pyrolytic Carbon frame Supporting
`hinge elements and de?ning a lea?et pivot axis and a ?exible
`lea?et body 'attached to the frame and de?ning a lea?et
`abuttlhg Seetleh extehdlhg from one slde of the Valve frame
`and an eeehldihg Section eXtehehhg from the Other Side Of the
`valve frame to an arcuate lea?et seat. In the closing phase of
`operation, the abutting sections of the lea?et bodies contact
`one another in an abutting contact band, and the arcuate
`lea?et seats bear against arcuate seat regions of the valve
`body The seat regions of the valve body may also be coated
`
`With an elastomeric material'
`
`23 Claims, 11 Drawing Sheets
`
`NORRED EXHIBIT 2114 - Page 1
`Medtronic, Inc., Medtronic Vascular, Inc.,
`& Medtronic Corevalve, LLC
`v. Troy R. Norred, M.D.
`Case IPR2014-00110
`
`5,178,632
`
`1/1993 Hanson . . . . . . . .
`
`. . . . . . .. 632/2
`
`623/1
`5,370,684 12/1994 Vallana et al.
`424/426
`5,447,724
`9/1995 Helmus et al. ..
`5,500,016
`3/1996 Fisher ........................................ .. 623/2
`
`

`

`U.S. Patent
`US. Patent
`
`0a. 31, 2000
`Oct. 31, 2000
`
`Sheet 1 0f 11
`Sheet 1 0f 11
`
`6,139,575
`6,139,575
`
`
`
`$
`as
`22
`
`NORRED EXHIBIT 2114 - Page 2
`NORRED EXHIBIT 2114 - Page 2
`
`

`

`US. Patent
`U.S. Patent
`
`0a. 31, 2000
`Oct. 31, 2000
`
`Sheet 2 0f 11
`Sheet 2 0f 11
`
`6,139,575
`6,139,575
`
`
`
`NORRED EXHIBIT 2114 - Page 3
`NORRED EXHIBIT 2114 - Page 3
`
`

`

`U.S. Patent
`
`Oct. 31, 2000
`
`Sheet 3 0f 11
`
`6,139,575
`
`NORRED EXHIBIT 2114 - Page 4
`
`

`

`U.S. Patent
`US. Patent
`
`0a. 31, 2000
`Oct. 31, 2000
`
`Sheet 4 0f 11
`Sheet 4 0f 11
`
`6,139,575
`6,139,575
`
`
`
`NORRED EXHIBIT 2114 - Page 5
`NORRED EXHIBIT 2114 - Page 5
`
`

`

`U.S. Patent
`
`Oct. 31, 2000
`
`Sheet 5 0f 11
`
`6,139,575
`
`NORRED EXHIBIT 2114 - Page 6
`
`

`

`U.S. Patent
`US. Patent
`
`0a. 31, 2000
`Oct. 31, 2000
`
`Sheet 6 0f 11
`Sheet 6 0f 11
`
`6,139,575
`6,139,575
`
`
`
`NORRED EXHIBIT 2114 - Page 7
`NORRED EXHIBIT 2114 - Page 7
`
`

`

`U.S. Patent
`US. Patent
`
`0a. 31, 2000
`Oct. 31, 2000
`
`Sheet 7 0f 11
`Sheet 7 0f 11
`
`6,139,575
`6,139,575
`
`
`
`NORRED EXHIBIT 2114 - Page 8
`NORRED EXHIBIT 2114 - Page 8
`
`

`

`U.S. Patent
`US. Patent
`
`0a. 31, 2000
`Oct. 31, 2000
`
`Sheet 8 0f 11
`Sheet 8 0f 11
`
`6,139,575
`6,139,575
`
`
`
`NORRED EXHIBIT 2114 - Page 9
`NORRED EXHIBIT 2114 - Page 9
`
`

`

`U.S. Patent
`
`0a. 31, 2000
`
`Sheet 9 0f 11
`
`6,139,575
`
`13,19
`
`FIG. l2
`
`NORRED EXHIBIT 2114 - Page 10
`
`

`

`U.S. Patent
`
`0a. 31, 2000
`
`Sheet 10 0f 11
`
`6,139,575
`
`FIG. l4
`
`K 23
`
`NORRED EXHIBIT 2114 - Page 11
`
`

`

`U.S. Patent
`
`0a. 31, 2000
`
`Sheet 11 0f 11
`
`6,139,575
`
`H2
`
`/ I20
`
`NORRED EXHIBIT 2114 - Page 12
`
`

`

`6,139,575
`
`1
`HYBRID MECHANICAL HEART VALVE
`PROSTHESIS
`
`FIELD OF THE INVENTION
`
`The present invention pertains to prosthetic mechanical
`heart valves and in particular, to bi-lea?et and tri-lea?et
`mechanical valves formed With rigid hinge mechanism and
`?exible lea?ets.
`
`BACKGROUND OF THE INVENTION
`During each cardiac cycle, the natural heart valves alter
`natively open to alloW blood to ?oW through them and then
`close to block blood ?oW. During systole, the mitral and
`tricuspid valves close to prevent reverse blood ?oW from the
`ventricles to the atria. At the same time, the aortic and
`pulmonary valves open to alloW blood ?oW into the aorta
`and pulmonary arteries. Conversely, during diastole, the
`aortic and pulmonary valves close to prevent reverse blood
`?oW from the aorta and pulmonary arteries into the
`ventricles, and the mitral and tricuspid valves open to alloW
`blood ?oW into the ventricles. The cardiac valves open and
`close passively in response to blood pressure changes oper
`ating against the valve lea?et structure. Their valve lea?ets
`close When forWard pressure gradient reverses and urges
`blood ?oW backWard and open When forWard pressure
`gradient urges blood ?oW forWard.
`In certain individuals, the performance of a natural heart
`valve is compromised due to a birth defect or becomes
`compromised due to various disease processes. Surgical
`repair or replacement of the natural heart valve is considered
`When the natural heart valve is impaired to an extent such
`that normal cardiac function cannot be maintained. The
`natural heart valve can be replaced by homograft valves
`obtained from the same species (e.g., human donor heart
`valves), heterograft valves acquired from different species,
`and prosthetic mechanical heart valves.
`The present invention is directed to improvements in
`prosthetic mechanical heart valves. Modern implantable
`mechanical heart valves are typically formed of a relatively
`rigid, generally annular valve body de?ning a blood ?oW
`ori?ce and an annular valve seat and one or more occluders
`that are movable betWeen a closed, seated position in the
`annular valve seat and an open position at an angle to the
`valve body axis. These components of mechanical heart
`valves are made of blood compatible, non-thrombogenic
`materials, e.g., pyrolytic carbon and titanium. A bio
`compatible, fabric seWing ring is typically provided around
`the exterior of the valve body to provide an attachment site
`for suturing the valve prosthesis into a prepared valve
`annulus. The occluder(s) is retained and a prescribed range
`of motion is de?ned by a cooperating hinge mechanism or
`other restraining mechanism. Such prosthetic heart valves
`function essentially as check valves in Which the occluder(s)
`responds to changes in the relative blood pressure in the
`forWard and reverse directions as described above and move
`betWeen their open and closed positions.
`TWo approaches to mechanical heart valve design have
`been folloWed over the years. In a ?rst approach, the design
`of the mechanical heart valve structure has attempted to
`mimic natural heart valve structures in construction, appear
`ance and function. For example, in US. Pat. No. 4,556,996,
`a valve design is proposed using molded elastomer, trian
`gular ?aps that extend inWardly into the annulus of a ring
`shaped valve body that appears to be intended to mimic
`tricuspid heart valves. The ?aps and ring-shaped body are
`integrally formed of Delrin or a similar hard plastic and
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`covered With an elastomer. The ?aps are intended to bend
`betWeen open and closed positions by integrally formed
`hinges at the junctions of the ?aps and the ring shaped body.
`This approach has also led to a number of proposed
`designs to mimic the operation of a natural tricuspid valve
`employing ?aps formed of thin plastic membranes attached
`to the valve body and to struts extending doWnstream from
`the valve body leaving the ?aps With free ?ap edges. In
`operation, the three ?aps balloon outWard in the open
`position to de?ne a cylindrical annulus for blood ?oW. In the
`closed position, the free ?ap edges of the three ?aps collapse
`against one another. A variety of such mechanical heart
`valve prostheses are described in US. Pat. Nos. 4,222,126,
`4,364,127, 5,500,016 and 5,562,729, incorporated herein by
`reference.
`The ?exible valve lea?ets of the designs folloWing this
`?rst approach have not been successfully clinically imple
`mented in part because the lea?et materials and integral
`hinge mechanisms cannot be shoWn to be reliable and
`immune from fracture or tear over long term use. It is also
`Well knoWn that calcium mineral deposits on the ?aps causes
`calci?cation of lea?ets. The calci?ed lea?ets become rigid
`and fail to open and close properly. Their durability are
`greatly reduced and valve failure alWays occurs at the
`calci?ed location. Moreover, the integral hinge structures
`are in loW blood ?oW regions and blood stagnation in those
`regions can contribute to the accretion of thrombus forma
`tion and also cause the failure of these valves.
`In the second approach, less attention is paid to trying to
`mimic the appearance and function of natural heart valve
`?aps, and more attention is paid to maximiZing reliability of
`operation and hemodynamic function. Such mechanical
`heart valve prostheses have employed other occluders and
`hinge or occluder restraint mechanisms that do not resemble
`?aps and integral ?ap hinges. A Wide variety of such
`mechanical heart valve designs have been proposed and/or
`clinically used in the past. For example, US. Pat. No.
`3,911,502 describes mechanical heart valves employing a
`spherical ball in a cage that moves in the cage into and out
`of engagement With an annular valve body seat in response
`to the blood ?oW due to normal pumping action of the heart.
`The spherical ball Was formed of a variety of materials
`including metals, plastics, and silicone rubber.
`Other early heart valve prostheses employed occluders in
`the form of a circular disc restrained Within cage struts or by
`disk mounted struts for movement betWeen open and closed
`disk positions in response to blood pressure changes, as
`shoWn, for example in US. Pat. Nos. 3,722,004 and 3,396,
`409. In the ’004 patent, the disk is formed of a pyrolytic
`carbon or metal ring coated With silicone rubber except for
`the periphery 20. The periphery 20 contacts the sides of the
`struts to restrain movement of the disk betWeen the disk
`open and disk closed positions. The silicone rubber strikes
`the ends of the struts to stop movement of the disk in the disk
`open position, and the silicone rubber coating ?exes to
`reduce noise and shock.
`Heart valve prostheses using such spherical ball or cir
`cular disk occluders provide poor hemodynamic function
`since the major surfaces of each such occluder remain
`perpendicular to the blood ?oW When the occluder is in the
`open position and therefore they impede blood ?oW. These
`types of valve designs created signi?cant pressure drop and
`energy loss. Moreover, the cage and strut restraints project
`ing from the annular valve body can interfere With heart
`tissue and make implantation dif?cult or impossible in
`certain valve replacement locations. In addition, such
`
`NORRED EXHIBIT 2114 - Page 13
`
`

`

`6,139,575
`
`3
`restraint structures are dif?cult to manufacture With the
`annular valve body in a manner that assures adequate
`mechanical reliability over years of implantation. Fractures
`have been reported to have occurred at junctions that Were
`Welded together.
`A Wide variety of pivoting disk heart valve prostheses
`have been developed and clinically used Wherein a single
`circular disk of pyrolytic carbon cooperates With strut and
`stop structures to pivot betWeen a disk open position and a
`disk closed position. The Medtronic HallTM mechanical
`heart valve employs a strut machined from the titanium
`block forming the annular heart valve body that is extended
`through a central opening in the disk to restrain its pivotal
`movement. Such a single pivoting disk mechanical valve
`design is reliable, but the opening angle of the disk in the
`disk open position is limited to less than 90°.
`More recently, clinically used, bi-lea?et heart valve pros
`theses have been developed that employ a pair of semi
`circular or semi-elliptical plates or lea?ets that are coupled
`to the annular heart valve base or body through pivot hinge
`mechanisms that alloW the lea?ets to pivot on lea?et pivot
`axes betWeen lea?et open and seated, closed positions. The
`valve body has an interior side Wall de?ning a blood ?oW
`ori?ce having a central blood ?oW axis centrally located
`With respect to the interior surface. The valve body also has
`?rst and second pairs of valve body hinge elements, eg
`recesses, and ?rst and second valve body seat regions. The
`pairs of valve body hinge elements provide opposed pairs of
`hinge pivot points and a pivot axis that extends across the
`valve annulus and is offset from the central axis of the valve
`annulus.
`In such bi-lea?et valve con?gurations, tWo mirror image
`lea?ets are typically disposed in opposed or mirror image
`relation to one another for alternately blocking blood ?oW in
`an in?oW direction When seated in a lea?et closed position
`and then alloWing the ?oW of blood through said blood ?oW
`ori?ce in an out?oW direction When in a lea?et open
`position. Upon closure, each valve lea?et occludes or closes
`a half section of the annular valve ori?ce or valve annulus.
`Generally, each lea?et is generally semi-circular in shape
`and has generally opposed, in?oW and out?oW, lea?et major
`surfaces and a peripheral edge extending betWeen the
`opposed lea?et major surfaces. A lea?et seat section of the
`peripheral edge is formed to seat against a valve body seat
`region When in the closed position. Each lea?et can rotate
`about a lea?et pivot axis extending betWeen a pair of lea?et
`hinge elements, e.g., outWardly projecting lea?et ears, that
`cooperate With a pair of valve body hinge elements, e.g., the
`opposed pair of hinge recesses. The lea?ets are typically
`planar in pro?le, but curved or elliptical lea?ets have been
`proposed.
`Such mechanical heart valves are typically designed in
`someWhat differing pro?le con?gurations for replacement of
`different impaired natural heart valves. HoWever, the basic
`in vivo operating principle is similar regardless of con?gu
`ration. Using an aortic valve as an example, When blood
`pressure rises in response to left ventricle contraction or
`systole in each cardiac cycle, the lea?ets of such a valve
`pivot from a closed position to an open position to permit
`blood ?oW past the lea?ets in an out?oW direction. When the
`left ventricle contraction is complete, blood tends to ?oW in
`the opposite, in?oW direction in diastole in response to the
`back pressure. The back pressure causes the aortic valve
`lea?ets to close in order to maintain arterial pressure in the
`arterial system.
`The most Widely accepted type of bi-lea?et heart valve
`presently used mounts its lea?ets for pivoting movement by
`
`10
`
`15
`
`25
`
`35
`
`45
`
`55
`
`65
`
`4
`means of a pair of rounded ears extending radially outWardly
`from opposed edges of the lea?ets to ?t Within rounded
`hinge recesses in opposed ?at surfaces of the valve body side
`Wall. Such bi-lea?et valves are exempli?ed by the mitral
`valve depicted in US. Pat. No. 4,276,658 and the aortic
`heart valve depicted in US. Pat. No. 5,178,632, both incor
`porated herein by reference.
`More particularly, the conventional lea?et ears are
`received Within curved hinge recesses extending radially
`into opposed ?at surfaces of thickened Wall sections inside
`the annulus of the generally cylindrical or annular valve
`body. Each hinge recess is designed in at least one respect
`to match the shape of the lea?et ear and is bounded by sets
`of lea?et stop surfaces angled to de?ne the extreme open and
`closed lea?et positions. In other Words, Where the ear is
`formed as a portion of a circle having a given radius, the
`counterpart hinge recess is formed as a semicircle having a
`slightly greater radius. An inverse arrangement of the ear
`and recess hinge mechanism is depicted in US. Pat. No.
`5,354,330, incorporated herein by reference, Whereby the
`lea?et ear is replaced by a lea?et recess, and the hinge recess
`is replaced by a complementary shaped hinge boss.
`To achieve the pivoting mechanism, the mating surfaces
`of the ears and recesses are precisely machined so as to
`provide a small but de?nite Working clearance for the ears
`to pivot about the necked doWn pivot surface and be retained
`Within the hinge recesses. During valve assembly, the annu
`lar valve body is deformed or distended so that the lea?et
`ears may be inserted into the respective hinge recesses. Each
`manufactured heart valve is then lab tested “dry” to ensure
`that the lea?ets are held tightly enough to be secure against
`falling out of their hinge recesses, but are not so tightly
`engaged so as to create a binding or restricted valve action.
`The range of lea?et motion is typically controlled by pins
`or ramps or opposed side stops of the hinge recesses or by
`hinge bosses in the valve body. In one format described in
`the above-incorporated ’632 patent, the hinge recess is
`generally spherical and bounded by open and closed stop
`surfaces of a stop member projecting into the recess. In the
`other formats depicted in the above-incorporated, ’658
`patent, each hinge recess has an elongated “boW-tie” or
`“butter?y” appearance created by the inWard angulation of
`opposed side edges extending from in?oW and out?oW end
`edges and meeting at opposite disposed, necked doWn, pivot
`points or surfaces intermediate the end edges.
`A great deal of effort has been devoted to controlling the
`range of movement and the acceleration of the lea?ets
`betWeen the open and closed positions to both control noise
`and decrease Wear or the possibility of lea?et fracture.
`Bi-lea?et mechanical heart valves are knoWn to be noisy, in
`the sense that patients can frequently hear the seating of the
`valve lea?et peripheral edges against the valve seats upon
`closure. It is desirable for patient comfort to provide a
`bi-lea?et design that minimiZes the distraction of lea?et
`seating noise.
`It is also knoWn that blood cells are extremely fragile and
`delicate and can be damaged and/or destroyed When trapped
`in the valve seat regions during closure of the valve lea?et
`or in the Wiping area of the valve lea?et ears and hinge
`recesses or betWeen the lea?et ears and the open and closed
`stop surfaces. The Wiping areas of the hinge recesses have
`the highest potential of thrombus formation and emboli
`entrapment Which can accumulate therein, impair the move
`ment of the valve lea?ets, and result in valve failure requir
`ing surgical intervention. To this time, no design has been
`successful in eradicating this problem. Consequently,
`
`NORRED EXHIBIT 2114 - Page 14
`
`

`

`5
`patients receiving current bi-lea?et mechanical heart valves
`are prescribed continuous blood anticoagulation therapy to
`prevent thrombus formation and thromboemboli. In our
`commonly assigned US. patent application Ser. No. 08/898,
`144 ?led Jul. 22, 1997, and entitled MECHANICAL
`HEART VALVE PROSTHESIS, We present an improved
`hinge design that is intended to optimiZe Washing of the
`hinge regions and decrease these problems of conventional
`hinge mechanisms of the type described above.
`In operation, the valve lea?ets accelerate rapidly as the
`lea?ets move from the lea?et open position to the lea?et
`closed position during the closing phase in response to a
`change of blood pressure. It is dif?cult to decelerate the
`lea?ets before the arcuate seat section of the lea?et periph
`eral edge strikes the corresponding arcuate seat region of the
`annular valve body. Since a conventional mechanical heart
`valve lea?et (disk) utiliZed rigid material, e.g., pyrolytic
`carbon, the momentum of the rotating rigid lea?et (disk) and
`its surrounding ?uid creates a high impact force due to the
`sudden stop When the arcuate seat section of the lea?et
`peripheral edge contacts the corresponding arcuate seat
`region of the annular valve body. This high impact force
`damages all blood elements entrapped in the contact region
`of the lea?et peripheral edge because the impact force is far
`beyond the bearable limit of any blood element and the
`dimension of this contact region is tWo orders of magnitude
`larger than any blood element. Blood hemolysis in clinical
`observation is one of the typical results from this high
`impact force.
`Moreover, the blood ?oW pressure at the in?oW side of the
`conventional mechanical heart valve lea?et peripheral edge
`can drop to near vacuum pressure due to a Water hammer
`effect upon lea?et closure. At the instant of a lea?et closure,
`blood volume proximal to the lea?et peripheral edge at the
`in?oW side tends to separate from the lea?et surface due to
`the moving momentum of ?uid column and the abruptly
`stopping of the rigid lea?et. This ?oW separation can create
`a very loW pressure in a very short time span, usually less
`than one milli-second. This very loW pressure in the Water
`hammer effect has the potential to generate cavitation Which,
`from occurring to vanished, is less than 50 micron seconds.
`Material corrosion, pitting and degradation of a lea?et
`surface caused by cavitation has been observed in clinical
`use in a feW mechanical heart valves. Should cavitation
`occur, the explosion force of cavitation bubble in a very
`short time duration can easily damage blood elements near
`cavitation sites. Even if no cavitation occurs, the loW pres
`sure ?eld at the in?oW side of the lea?et peripheral edge can
`cause damage to blood elements by generating high surface
`tension on surface membranes of blood elements.
`Also, after the valve is closed, localiZed high speed blood
`?oW leakage has been observed on all the current mechani
`cal heart valves. The blood ?oW leakage jets occur at the
`gaps betWeen lea?et and valve housing due to the large
`transvalvular pressure gradient in the valve closing phase.
`The reported shear stresses of leakage jets are beyond the
`surface tensile stress limits of any blood element surface
`membranes. Therefore, these leakage jets not only reduce
`the ef?ciency of a passive mechanical heart valve, but also
`damage blood elements in the leakage stream.
`
`5
`
`15
`
`25
`
`35
`
`45
`
`55
`
`SUMMARY OF THE INVENTION
`It is therefore an object of the present invention to
`minimiZe these problems associated With existing pivoting
`lea?et, mechanical heart valves.
`In accordance With the ?rst feature of the present
`invention, a valve lea?et having at least one lea?et hinge
`
`65
`
`6,139,575
`
`6
`element is provided for cooperatively engaging With a valve
`body hinge element to enable movement of the valve lea?et
`betWeen a lea?et open position alloWing blood ?oW through
`the valve body blood ?oW ori?ce and a lea?et closed
`position for blocking blood ?oW through the blood ?oW
`ori?ce. The valve lea?et has generally opposed, in?oW and
`out?oW, lea?et major surfaces bounded by a peripheral edge
`extending betWeen the opposed lea?et major surfaces. The
`peripheral edge is formed at least in part to provide a lea?et
`seat for engaging against the valve body seat region.
`The valve lea?et is formed in a hybrid manner of a
`relatively rigid valve lea?et skeleton or frame and a rela
`tively ?exible valve lea?et body adhered to the frame
`formed of an elastic, bio-compatible material. The valve
`body elastic material extends over and is adhered to about at
`least a portion of the valve lea?et frame and extends aWay
`from the valve lea?et frame to form at least a portion of the
`opposed lea?et major surfaces and the peripheral edge. The
`lea?et body material has a resilience and thickness that
`alloWs the lea?et seat to be deformed into a contact band
`With the valve body seat region to absorb contact shock
`When the lea?et moves into the lea?et closed position. The
`valve lea?et frame is coupled With the valve lea?et hinge
`element and formed of a dimensionally rigid, bio
`compatible, material providing dimensional rigidity to a
`portion of the valve lea?et and the lea?et hinge element. The
`valve lea?et frame enables the cooperative engagement of
`the valve body hinge element With the valve lea?et hinge
`element and governs movement of the valve lea?et betWeen
`the lea?et open and closed positions With respect to the
`blood ?oW ori?ce.
`The lea?et frame preferably extends in a lea?et pivot axis
`direction and comprises ?rst and second valve lea?et hinge
`elements at the opposite ends of the lea?et pivot axis. The
`valve body is formed With ?rst and second valve body hinge
`elements for receiving the ?rst and second valve lea?et
`hinge elements, respectively, for alloWing pivotal movement
`of the valve lea?et about the lea?et pivot axis betWeen the
`lea?et open and lea?et closed positions. The lea?et body
`further comprises a coating of the elastic, bio-compatible
`material extending over the lea?et frame and forming sub
`stantially all of the opposed, lea?et major surfaces.
`Preferably, the invention is implemented in a bi-lea?et
`valve having tWo such lea?ets that are hinged for pivotal
`movement betWeen lea?et open and lea?et closed positions
`With respect to ?rst and second portions of the annular blood
`?oW ori?ce and ?rst and second valve body seat regions.
`Preferably, each valve lea?et frame extends betWeen a pair
`of lea?et hinge elements that cooperatively engage a pair of
`valve body hinge elements together de?ning a dimensionally
`stable pivot axis. The ?rst and second valve lea?ets have
`lea?et bodies extending over substantially all of the lea?et
`frames formed as described in the preceding paragraph to
`provide ?rst and second respective lea?et occluding sections
`bounded by arcuate seat sections of the peripheral edges
`thereof that deform When seated against respective ?rst and
`second valve body seat regions in the lea?et closed position.
`This deformation of the resilient lea?et body blocks blood
`?oW leakage and eliminates leakage jets through the arcuate
`seat sections of the peripheral edges.
`In such bi-lea?et mechanical heart valves, each of the ?rst
`and second valve lea?ets preferably further comprise ?rst
`and second respective abutting sections of the peripheral
`edge formed to abut against one another When the ?rst and
`second valve lea?ets are in the lea?et closed positions. The
`contact of the abutting sections blocks the leakage ?oW of
`blood through any space betWeen the ?rst and second valve
`
`NORRED EXHIBIT 2114 - Page 15
`
`

`

`6,139,575
`
`7
`lea?ets and through the blood ?oW ori?ce. The abutting
`section of each valve lea?et is formed by the extension of the
`elastic, bio-compatible material aWay from the lea?et frame
`having a resilience and thickness that provides mutual
`deformation of the ?rst and second abutting sections into a
`contact band With one another and absorption of contact
`shock therebetWeen When the lea?ets move into the lea?et
`closed positions. The mutual contact of the abutting sections
`also decreases the intensity of contact of the arcuate seat
`section against the respective valve body seat region.
`The lea?et body is also ?exible in a region of the lea?et
`extending inWardly of the arcuate seat section and to the
`lea?et frame to alloW the lea?et to ?ex in response to blood
`pressure changes in the ?oW ?eld. This ?exibility of the
`lea?et alloWs the lea?et occluding section to effectively
`bend and close earlier than a rigid metal lea?et. The ?ex
`ibility also decreases the closing velocity of the lea?et and
`diminishes the closing impact of the arcuate seat section
`against the respective valve body seat region. The reduced
`impact effect plus the deformability of the lea?et can greatly
`reduce or eliminate the propensity of potential cavitation at
`the in?oW surface of the lea?et peripheral edge.
`In order to promote adherence of the valve lea?et body
`With the valve lea?et frame, the valve lea?et frame is formed
`With opposed, frame major surfaces With a plurality of
`openings extending through the valve lea?et frame betWeen
`the opposed, major frame surfaces. The lea?et body further
`comprises a coating of the elastic, bio-compatible material
`extending over the lea?et frame and through the plurality of
`openings and forming substantially all of the opposed,
`lea?et major surfaces.
`The method of adhering the lea?et body to the lea?et
`frame preferably comprises pre-treatment of the relatively
`rigid lea?et frame and molding of the elastomeric material
`about the frame to form the lea?et body. The lea?et frame is
`preferably formed of pyrolytic carbon coated on a graphite
`substrate, even more preferably pyrolytic carbon that is
`treated With certain chemical solutions such as solutions
`based on silane or siloxane chemistries. The lea?et body is
`preferably molded about the treated lea?et frame from
`silicone rubber or other elastomers. Compounds may be
`added to silicone rubber before it is molded to provide
`radio-opacity. The polymeric surfaces of the lea?et may be
`modi?ed or treated With anticoagulation and/or anti
`calci?cation agents to prevent any potential thrombus for
`mation and/or lea?et calci?cation.
`The valve frame provides for the structural rigidity and
`support of the valve lea?et hinge elements and absorbs
`shocks to the valve lea?et incurred in the opening and
`closing phases. The valve body moderates shocks and pro
`vides for the soft closure that reduces blood damage and
`mechanical deterioration of the valve lea?et structure. The
`resulting need for anti-coagulation drug therapy may be
`reduced.
`The hybrid valve lea?et alloWs the pivoting lea?et
`mechanical heart valve to enjoy the gentle and smooth
`closing behavior of a tissue valve While retaining the long
`life and reliability of the mechanical heart valve. Because of
`the large thickness and strength of this lea?et design, poten
`tial calci?cation and structural deterioration as seen in
`conventional polymeric valves are minimiZed or eliminated.
`These principles of construction and operation can also be
`applied to multi-lea?et mechanical heart valve prostheses,
`particularly, tri-lea?et heart valves, and the resultant advan
`tages can enjoyed in such multi-lea?et heart valves.
`
`10
`
`15
`
`25
`
`35
`
`45
`
`55
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`These and other objects, advantages and features of the
`present invention Will be appreciated as the same becomes
`
`65
`
`8
`better understood by reference to the folloWing detailed
`description of the preferred embodiment of the invention
`When considered in connection With the accompanying
`draWings, in Which like numbered reference numbers des
`ignate like parts throughout the ?gures thereof, and Wherein:
`FIG. 1 is an isometric vieW from the in?oW side of a
`bi-lea?et mechanical heart valve in an aortic con?guration
`incorporating the improved hybrid lea?et of the present
`invention;
`FIG. 2 is a plan vieW of an exemplary planar hybrid valve
`lea?et in accordance With a ?rst embodiment of the inven
`tion vieWed from the in?oW surface thereof;
`FIG. 3 is a plan vieW of a variation of the hybrid valve
`lea?et of FIG. 2 vieWed from the in?oW surface thereof;
`FIG. 4 is a partial cross-section, isometric vieW of the
`hybrid valve lea?et of FIGS. 2 and 3 taken along lines 4—4
`of FIGS. 2 and 3;
`FIG. 5 is a partial cross-section, isometric vieW of the
`hybrid valve lea?et of FIGS. 2 and 3 seated in the lea?et
`closed position against a valve body seat region;
`FIG. 6 is a side cross-section vieW taken along lines 6—6
`of FIG. 1 of a pair of the hybrid valve lea?ets of FI