United States Patent [19]
`Reger
`
`[54] METHOD OF MAKING AN ARTIFICIAL
`HEART VALVE STENT
`
`[75] Inventor: Vincent A. Reger, Portland, Oreg.
`
`[73] Assignee: Reger Medical Inc., Portland, Oreg.
`
`[21] Appl. No.: 286,162
`[22] Filed:
`Aug. 4, 1994
`
`Related US. Application Data
`
`[63] Continuation of Ser. No. 84,663, Jun. 28, 1993, abandoned,
`which is a continuation of Ser. No. 834,416, Feb. 12, 1992,
`Pat. No. 5,258,023.
`
`[51] Int. Cl.6 ............................. .. A61B 19/00; A61F 2/24
`[52] US. Cl. ............................... .. 128/898; 623/2; 623/66;
`623/901
`[58] Field of Search .................................. .. 623/2, 11, 66,
`623/901, 12; 128/898; 112/262.1; 29/890.12,
`890.124, 890.126, 890, 128, 890.132
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`9/1969 Siposs ....................................... .. 623/2
`3,466,671
`8/1978 Carpentieretal.
`.... .. 623/2
`4,106,129
`4,626,255 12/1986 Reichart et al.
`.... .. 623/2
`
`4,680,031
`
`7/1987 Alonso . . . . . . . . . .
`
`. . . . .. 623/2
`
`.... .. 623/2
`5,163,954 11/1992 Curio et a1.
`5,258,023 1l/1993 Reger ........................................ .. 623/2
`
`1lllllllllllllllIlllIllllllllllmlglllllllllllllllllllllllllllll
`
`[11] Patent Number:
`[45] Date of Patent:
`
`5,469,868
`Nov. 28, 1995
`
`Attorney, Agent, or Finn-Foster & Foster; Lynn G. Foster
`[57]
`ABSTRACT
`A novel, long lasting prosthetic heart valve compatible with
`implantation in a human natural heart valve annulus. The
`prosthetic heart valve comprises a trilea?et heart valve
`apparatus which in form, dimension, and function resembles
`a human trilea?et heart valve, but which is formed of
`synthetic resinous material. A seamless supporting frame
`capable of annular deformation and limited perimetric
`expansion during each heartbeat is totally enveloped in an
`essentially biologically inert cylindrical cover to form a cusp
`supporting stent for the valve lea?et apparatus. The free top
`and bottom edges of the cylindrical cover are disposed on
`the exterior of the stent and everted outward to provide at
`least one sewing ring. Valve embodiments comprise aortic
`and mitral implantable valves. For the aortic implant, the
`outwardly everting free sewing ring forming edges are
`separated by circumferentially disposed compressible and
`expandable material which provides a pliable, compliant
`interface between the valve and the natural valve annulus at
`the implanting site. In one embodiment, the synthetic trileaf
`let heart valve apparatus is formed by a unicast mold. In
`another embodiment, the heart valve apparatus is formed
`from a cylinder of synthetic resinous material. Valve sewing
`ring covers can be selectively impregnated with antibiotic
`medicants to substantially eliminate early post implant
`infection. Use of non-thrombogenic biochemically inert
`materials in a valve apparatus which mimics operation of a
`natural heart valve essentially eliminates the need for long
`term administration of anticoagulants.
`
`Primary Examiner-Paul B. Prebilic
`
`3 Claims, 5 Drawing Sheets
`
`Medtronic, Medtronic Vascular,
`and Medtronic CoreValve
`Exhibit 1007 - Page 1
`
`

`

`US. Patent
`
`Nov. 28, 1995
`
`Sheet 1 of 5
`
`5,469,868
`
`Medtronic, Medtronic Vascular,
`and Medtronic CoreValve
`Exhibit 1007 - Page 2
`
`

`

`US. Patent
`
`Nov. 28, 1995
`
`Sheet 2 of 5
`
`5,469,868
`
`Medtronic, Medtronic Vascular,
`and Medtronic CoreValve
`Exhibit 1007 - Page 3
`
`

`

`US. Patent
`
`Nov. 28, 1995
`
`Sheet 3 of 5
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`5,469,868
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`332
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`330
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`340
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`336
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`Medtronic, Medtronic Vascular,
`and Medtronic CoreValve
`Exhibit 1007 - Page 4
`
`

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`U.S. Patent
`
`Nov. 28, 1995
`
`Sheet 4 of 5
`
`5,469,868
`
`Medtronic, Medtronic Vascular,
`and Medtronic CoreValve
`Exhibit 1007 - Page 5
`
`

`

`US. Patent
`
`Nov. 28, 1995
`
`Sheet 5 of 5
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`5,469,868
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`I55
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`‘ 270
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`xxx
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`4443/44?
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`6
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`Medtronic, Medtronic Vascular,
`and Medtronic CoreValve
`Exhibit 1007 - Page 6
`
`

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`5,469,868
`
`1
`METHOD OF MAKING AN ARTIFICIAL
`HEART VALVE STENT
`
`CONTINUITY
`
`This application is a continuation of my U.S. patent
`application Ser. No. 08/084,663, ?led Jun. 28, 1993, now
`abandoned, which is a continuation of U.S. patent applica
`tion Ser. No. 07/834,416, ?led Feb. 12, 1992, now U.S. Pat.
`No. 5,258,023.
`
`FIELD OF INVENTION
`
`This invention relates to implantable heart valves and in
`particular to long-lasting implantable prosthetic heart valves
`comprising valve lea?ets made from synthetic materials.
`
`BACKGROUND AND DESCRIPTION OF
`RELATED ART
`
`20
`
`Two types of replacement heart valve prostheses are
`generally known in the art. A ?rst replacement type com
`prises totally mechanical heart valves which e?ect unidirec
`tional blood ?ow through the use of a device using a
`mechanical closure. The more common mechanical heart
`valves comprise pressure responsive, pressure directed
`movement of a ball in a cage or tilting or caged discs.
`Examples of pressure responsive, pressure directed ball
`movement devices are found in U.S. Pat. Nos. 3,263,239,
`3,365,728, 3,466,671, 3,509,582, 3,534,410, and 3,723,996.
`Earliest valve designs were strictly concerned with provid
`ing a one-way valve which could be used as a replacement
`for natural mitral and aortic valves. The earliest known
`arti?cial caged ball prothesis was ?rst successfully used for
`treatment of cardiac valve disease in 1953. With improve
`ments in valves and medical procedures, caged valve pros
`thesis rapidly became commonplace in the early 1960’s.
`A source of historical and background information in
`Mechanical Valve Prostheses is found in The Fourth Edition
`of Thoracic and Cardiovascular Surgery, published in 1983
`by Appleton-Century-Crofts, a publishing division of Pren
`tice-Hall, inc. The earliest caged ball valves comprised
`stainless steel out?ow ori?ce and rib cages and silicone
`rubbber poppers. Such valves experienced a high incidence
`of thromboembolism associated with the out?ow ori?ces
`and rib cages. The silicone rubber poppers after a period of
`use often became grossly deformed with resulting incom
`petence.
`To slow the degeneration of the silicone rubber poppers,
`cloth and plastic coverings were provided for the metal
`parts. Such coverings resulted in effects of wear and tissue
`growth in the coverings. The tissue growth, especially in the
`coverings over struts of the cages led to a thickening of the
`struts which slowed or stopped ball movement. Fibrous
`growth across the ori?ce of the valve led to severe valvular
`stenosis.
`The use of hollow metal spheres and metal tracks in later
`models of the caged ball rib valves have overcome some of
`the original problems, and improvements continue to be
`made to make caged rib ball valve safer and more e?ica—
`crous.
`However, problems inherent with the geometry of the
`caged ball valve also leads to physiological problems with
`the use of the valve as a heart valve replacement prosthesis.
`The caged rib ball valve comprises three ori?ces through
`which blood must ?ow. The primary ori?ce is the ori?ce
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`through which blood passes from the effluent chamber being
`valved. From the primary ori?ce the blood passes through a
`secondary ori?ce de?ned by the cage and ball, the size of
`which is determined by the height of the cage and diameter
`of the ball. The third ori?ce is the hollow cylindrical path
`between the ball and cage and the surrounding in?uent
`chamber into which the blood ?ows from the e?luent
`chamber.
`The three ori?ce pattern in a caged ball valve requires
`sometimes di?icult tradeoifs to be made in design. For
`example, when the ball is large, the third ori?ce is relatively
`smaller leading to third ori?ce stenosis. When the ball is
`small, the primary ori?ce is small and relatively stenotic.
`Further, if travel of the ball in the cage is restricted, as may
`be required by physiological free space in either the ascend
`ing aorta or left ventricle of a patient, the second ori?ce size
`must be reduced with resulting relative stenosis thereat. For
`these reasons, even in a caged ball valve without physi
`ological or structural complications, use is restricted by the
`inherent three ori?ce geometry.
`Disc valves have been made in the form of caged disc
`valves and tilting disc valves. Disc valves are generally
`preferred over caged ball valves because of the inherent low
`pro?le con?guration of the disk valve. One of the major
`problems with disc valves and in particular with caged disc
`valves, is thrombogenicity. Other problems comprise
`obstructive characteristics inherent to the basic geometry of
`caged disc valves and degeneration of the disc occluder and
`strut fracture. Also hemolysis with disc prostheses is espe
`cially common.
`An example a tilting disc valve is found in U.S. Pat. No.
`4,892,540. Tilting disc valve prostheses have proved to be
`more satisfactory than the caged disc valves. The tilting disc
`valve prostheses generally have less hemolysis, lower cross
`valve gradients, and little wear of carbon pyrolyte discs.
`However, the tilting disc prostheses have a tendency to clot,
`and a strict anticoagulant regimen is required. Also move
`ment of the disc in close relation with the sewing ring
`generally increases chances of interference by contact with
`adjacent mural endocardium or aortic intima and requires
`extra care be taken to prevent interference with movement of
`the disc.
`A second replacement type of heart valve prothesis is the
`“tissue-type” valve which structurally resembles and func
`tions similarly to at least one of the human heart valves.
`Such valves are most often harvested from pigs or cows and
`are mounted on a prosthetic stent with an a?iliated sewing
`ring for attachment to the annulus of the valve being
`replaced. Problems related to the requirement for anticoagu
`lants are usually short term with “tissue-type” valves and
`failure of such valves is seldom abrupt.
`However, such valves are generally slowly rejected from
`the patient as a foreign body. The rejection is manifested as
`motion limiting calci?cation of the lea?ets of the “tissue
`type” valve and slowly ensuing functional failure. Such
`failure commonly necessitates replacement within ?fteen
`years of original implantation. Examples of devices which
`apply to human and other animal “tissue-type” valvular
`prostheses are found in U.S. Pat. Nos. 3,656,185 and 4,106,
`129. Two examples of currently manufactured and marketed
`“tissue-type” valves are the MITROFLOWTM Heart Valve
`by Mitro?ow International, Inc., 11220 Voyager Way, Unit
`1, Richmond, B.C., Canada V6X 351 and Bovine Pericardial
`Valve by Sorin Biomedical, S.P.A., 13040 Saluggia (VC),
`Italy.
`
`Medtronic, Medtronic Vascular,
`and Medtronic CoreValve
`Exhibit 1007 - Page 7
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`

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`5,469,868
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`3
`BRIEF SUMMARY AND OBJECTIONS OF THE
`INVENTION
`
`In brief summary, is novel invention alleviates all of the
`known problems related to the substantial and long term
`requirement for administrating anticoagulants, “tissue-type”
`rejection, stenotic operation especially with a low pro?le
`valve prostheses, thrombogenesis, and post placement infec
`tion. The invention is a long-lasting implantable prosthetic
`heart valve which contains no tissue component.
`The valve lea?et apparatus is produced as a unicast or
`extruded prosthetic valve lea?et apparatus and is devoid of
`tilting or traveling metal or plastic components. The inven
`tion comprises a stent which provides an implanting support
`for the valve lea?et apparatus. The stent has a novel sewing
`ring which provides a hard surface component to which
`anchoring sutures are tied and an optionally used soft
`component against which the anchoring valve receiving
`ori?ce of the heart is free to compliantly expand and contract
`as the heart beats.
`The stent comprises a frame which is fully covered by a
`biochemically inert or physiologically compatible shroud.
`The frame is generally a light weight, hollow cylinder,
`machined or trimmed to provide a suturing support ring,
`extended cusp stanchions, and interference free blood ?ow
`to the coronary arteries. The frame is joint free and is slightly
`deformable to conform to contractile changes of the heart.
`The shroud comprises two or three parts, depending upon
`use of the valve. A ?rst part of the shroud comprises a hollow
`cylindrical seamless material which has substantially the
`same diameter as the frame. The seamless material is
`inserted into the cylinder of the frame and folded outward
`and downward at the top and outward and upward at the
`bottom such that the top and bottom parts meet at a site at
`the mere medial part of the suturing support ring. If the
`:shroud is made of two parts, each top and bottom part is
`folded outward at the site to form a contiguous two-layered
`brim. The brim provides the hard surface component form
`ing a sewing ring for suturing the stent for the anchoring
`sutures. If the shroud comprises three parts, the top and
`bottom parts are folded outward to form two separated
`sewing rings.
`Above the sewing ring or rings, the shroud is trimmed and
`sewn or otherwise fused together such as by heat bonding to
`conform to the shape of the frame and provide an encom
`passing cover therefor. When the sewing rings are separated,
`a soft, compliant material is interposed to provide a cushion
`between the stent and the natural ori?ce in which the valve
`resides between the two sewing rings.
`Another part of each shroud is a brim cover. In the case
`of the two part shroud, the brim cover comprises a cylinder
`of material surrounding, folded over, and securely sutured to
`the two-layered brim to provide a tissue adhering cover
`above and below the brim. For the three part shroud, the
`brim area also comprises a cylinder of material. However, in
`this latter case, more central portions of the brim cover are
`folded and inserted between The interfaces between each
`brim and the soft compliant material, thereby providing a
`continuous tissue adhering cover which covers each brim,
`the soft compliant material and interface there between.
`Each brim cover is selectively complexed and impregnated
`with antibiotics to reduce the likelihood of infections, anti
`coagulant and endothelial cells or endothelial growth factors
`to selectively control incorporation of surrounding tissue of
`the natural ori?ce interface.
`The valve lea?et apparatus comprises a multiple leaf
`valve which resembles in form and function a natural heart
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`valve. The valve is a resilient synthetic resinous material
`part having an outside diameter which is substantially the
`same size as the stent. The valve lea?et apparatus may be
`formed by molding or extruding. The valve comprises a
`plurality of cusps which form medially disposed leaves
`which coapt upon closure to reduce lea?et wear and tear.
`When the synthetic resinous material from which the valve
`is molded is porous and chemically compatible, it is selec
`tively complexed and impregnated with antibiotic medica
`tions to decrease the risk of post placement valve infection
`and anticoagulants to totally eliminate the need for initial
`exogenous anticoagulation on the part of the patient. The
`valves are sutured or otherwise permanently attached to the
`stent.
`Accordingly, it is a primary object to provide a prosthetic
`heart valve having a mean-time-to-failure which is substan
`tially longer than the expected life span of the patient.
`It is another primary object to provide such a durable
`prosthetic heart valve which is simple in construction and
`low in manufacturing cost.
`It is a signi?cant object to provide a prosthetic heart valve
`con?gured entirely of biochemically-inert and biocompat
`ible materials.
`It is another signi?cant object to provide a heart valve
`which is devoid of adhesives or bonding resins which might
`be released into the bloodstream of a receiving patient over
`a period of time.
`It is another signi?cant object to provide a prosthetic heart
`valve comprising an arti?cial lea?et valve mechanism which
`is similar to a natural valve in shape and function and which
`is assembled into a stent which provides mounting support
`for the valve in a native ori?ce from which a natural valve
`has been excised.
`It is another signi?cant object to provide the prosthetic
`heart valve with a sewing ring comprising a superior and an
`inferior hard surface against which knots in anchoring
`sutures are securely a?ixed.
`It is a key object to provide at least one embodiment of a
`prosthetic heart valve con?gured to replace a natural mitral
`valve.
`It is another key object to provide at least one embodiment
`of a prosthetic heart valve conformably con?gured to
`replace a natural aortic valve.
`It is another key object provide the prosthetic heart valve
`with a soft potion interposed between superior and inferior
`hard valve anchoring surfaces which perimetrically expands
`between the the hard surfaces and a juxtaposed natural and
`somewhat irregular native valve annulus to form a conform
`able seal.
`It is still another key object to provide the soft portion
`comprising material which comprises a cover, the surface of
`which is permissive only to limited tissue ingrowth such that
`the soft portion is separable from the native valve annulus
`should removal of the valve become necessary.
`It is fundamental object to provide a stent which com
`prises a frame, a frame shroud or cover comprising a two
`part sewing ring which encompasses at least a large measure
`of the frame, and optional additional cover parts which cover
`otherwise uncovered parts of the frame in the area where the
`sewing ring is attached to the native valve ori?ce.
`It is signi?cant object to provide a stent which permits the
`prosthetic valve to deform slightly with heart motion thereby
`permitting lea?ets of the valve mechanism to coapt with a
`sliding motion to reduce wear at the free margins of the
`lea?ets.
`
`Medtronic, Medtronic Vascular,
`and Medtronic CoreValve
`Exhibit 1007 - Page 8
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`It is another signi?cant object to provide a stent frame
`which is capable of annular deformity and slight perimetric
`expansion such that the stent frame diametrally varies
`expansively and contractually with the natural valve ori?ce
`within which the stent frame is disposed,
`It is another signi?cant object to provide a stent which
`permits the prosthetic valve to expand and contract with the
`natural valve ori?ce in which the prosthetic valve resides to
`reduce tugging forces upon the sutures and thereby reduce
`the likelihood of eventual valve dehiscence.
`It is a basic object to provide a stent frame comprised of
`metal or synthetic resinous material which describes a
`continuous, seamless circular plane.
`It is an essential object to provide a stent frame which
`comprises a plurality of circumferentially-spaced, axially
`projecting cusp supports.
`It is consequential object to provide a stent frame com
`prising a plurality of windows which reduce the weight of
`the stent frame.
`It is another object to provide a stent frame comprising a
`series of holes therein which allow margins of a valve lea?et
`apparatus to be securely af?xed to the stent frame.
`It is vital object to provide a double walled shroud of
`bio-compatible material which covers at least a large mea
`sure of the stent frame.
`It is another vital object to provide the double walled
`envelope which comprises pockets which receive and cover
`the cusp supports of the stent frame.
`It is another signi?cant object to provide a stent frame
`enveloping cover which comprises superior and inferior
`members of a sewing ring by which the prosthetic heart
`valve is sewingly a?ixed about the native valve ori?ce.
`It is another fundamental object to provide the double
`Walled stent frame enveloping cover comprising a continu
`ous connection to each sewing ring.
`It is another important object to provide at least one
`sewing ring comprising a ?rm, knot supporting inferior and
`superior surface for sewingly al‘n'xing the prosthetic heart
`valve to the native valve ori?ce.
`It is another key object to provide a cover for the sewing
`rings and a soft, deformable, space ?lling material intenne
`diate portion interposed between two sewing rings, the space
`?lling material perimetrically expanding to ?ll and seal
`against a native valve annulus when the sewing rings are
`drawn tightly into place around the annulus.
`It is another key object to provide a soft, deformable
`intermediate portion which comprises material which results
`in variable incorporation of surrounding tissue, thereby
`providing optimal balance between ease of removal and
`prevention of infection.
`It is a notable object to provide a cover for the stent frame
`at least a part of which is impregnated with at least one
`active biochemical from a group comprising antibiotics,
`anticoagulant medications, endothelial cells or endothelial
`cell growth factors.
`It is a main object to provide a heart valve lea?et
`apparatus which resembles in form and function a human
`trilea?et heart valve.
`It is another main object to provide a valve mechanism
`which comprises no centrally disposed members during the
`time the valve is open.
`It is another main object to provide a valve lea?et appa
`ratus comprising members which move toward the inner
`surface of the stent when the valve is coursed with maximum
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`?ow thereby providing a valve having a ?ow cross section
`substantially as large as the stent.
`It is another notable object to provide a valve mechanism
`which comprises a trilea?et con?guration of substantially
`the same dimensions as a natural aortic valve thereby
`providing a prosthetic valve of relatively low silhouette
`compared to a caged ball valve.
`It is another fundamental object to provide a valve mecha
`nism which comprises a functionally continuous surface
`over all aspects of the valve.
`It is a principal object to provide a valve mechanism
`which is non-thrombogenic.
`It is another notable object to provide at least one valve
`lea?et apparatus which is impregnated with anticoagulant
`medication to eliminate the need for initial exogenous
`anticoagulation on the part of the patient.
`These and other objects and features of the present
`invention will be apparent from the detailed description
`taken with reference to accompanying drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a perspective of an implantable prosthetic aortic
`heart valve comprising a heart valve lea?et apparatus suit
`ably joined to a supporting stent and brim-formed double
`sewing rings seen partially covered by a brim cover, a
`portion of the brim covering portion of the apparatus being
`removed to reveal other details of the sewing rings.
`FIG. 2 is a perspective of the frame of the stent.
`FIG. 3 is a perspective of the frame and a length of
`foldable cylindrical covering material disposed therein as a
`?rst step in a stent assembly process.
`FIG. 4 is a perspective of steps following the step of FIG.
`3 in the stent assembly process wherein the covering mate
`rial is folded outward and over the frame at both the top and
`bottom and then folded outward to form double brim sewing
`rings of the implantable prosthetic aortic heart valve.
`FIG. 5 is a perspective of a partially completed aortic
`heart valve stent with the covering trimmed along dashed
`lines seen in FIG. 4 to encompass rising cusp supports of the
`frame.
`FIG. 6 is a perspective of a covered aortic heart valve stent
`wherein the trimmed cover is sewn together.
`FIG. 7 is a section along lines 7—7 of FIG. 6.
`FIG. 8 is a perspective of a covered stent for a mitral heart
`valve prosthesis.
`FIG. 9 is a section along lines 9—9 of FIG. 8.
`FIG. 10 is a perspective of a heart valve lea?et apparatus.
`FIG. 11 is a section along lines 11——11 of FIG. 10.
`FIG. 12 is a top elevation of a closed trilea?et valve.
`FIG. 13 is a top elevation of an open trilea?et valve.
`FIG. 14 is a perspective of the heart valve lea?et appa
`ratus incised along line 14—14 in FIG. 10 and opened for
`clarity of presentation.
`FIG. 15 is a perspective of a prosthetic heart valve lea?et
`apparatus wherein the lea?ets are lea?et models cast from a
`mold of a natural heart valve.
`FIG. 16 is an exploded perspective of the heart valve
`prosthesis seen in FIG. 1.
`FIG. 17 is a perspective of a cylinder of material used to
`cover a brim portion of the stent.
`FIG. 18 is an exterior perspective of a medial section of
`the aortic valve prosthesis stent of FIG. 7 showing the
`
`Medtronic, Medtronic Vascular,
`and Medtronic CoreValve
`Exhibit 1007 - Page 9
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`

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`5,469,868
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`7
`cylinder of material seen in FIG. 17 disposed about and
`securely a?ixed to the brim portion of the aortic valve stent.
`FIG. 19 is an exterior perspective of a medial section of
`the rrritral heart valve prosthesis stent of FIG. 9 showing the
`cylinder of material seen in FIG. 17 disposed about and
`securely a?ixed to the brim of the rnitral valve stent.
`FIG. 20 is a perspective of a cylinder of material from
`which a trilea?et valve is made.
`FIG. 21 is a perspective of the cylinder of material of FIG.
`20 sewn into a stent to form an aortic valve prosthesis, said
`valve being seen in a nearly fully open con?guration,
`FIG. 22 is a perspective of the aortic valve seen in FIG.
`21 rotated about a vertical axis and closed.
`
`DETAILED DESCRIPTION OF THE
`ILLUSTRATED EMBODIMENTS
`
`Reference is now made to The embodiments illustrated in
`FIGS. 1—22 wherein like numerals are used to designate like
`parts throughout.
`A ?rst illustrated embodiment of the invention, seen in
`FIG. 1, is a prosthetic aortic heart valve 10. Aortic heart
`valve 10 comprises a heart valve lea?et apparatus 20 and a
`heart valve lea?et apparatus supporting stent 30. Heart valve
`lea?et apparatus 20 is disposed medially to stent 30 and
`therein comprises three cusps 40, 50, and 60 which are
`similar in form and function to cusps of a natural heart valve.
`Stent 30 comprises three upright, cusp supports 70, 80, and
`90, each of which provides a vertical stay for the cusps 40,
`50, and 60.
`Further, in this embodiment, aortic valve 10 comprises
`two radially projecting sewing rings 100 and 102. Interposed
`between sewing rings 100 and 102 is a soft, deformable
`intermediate natural valve ori?ce interfacing portion 104,
`the purpose and character of which is provided in detail
`hereafter.
`Seen in part, covering sewing rings 100 and 102 and
`interfacing portion 104, is a brim cover 105. Brim cover 105
`is described in detail hereafter.
`While sewing rings may be di?erently constructed within
`the scope of the invention, in this ?rst illustrated embodi
`ment, sewing rings 100 and 102 are contiguous segments of
`a stent cover 106 which, in large measure, covers and
`protects a supporting frame 110, seen in FIG. 2, from
`biologic activity. The reasons for so making and the method
`for fabricating sewing rings 100 and 102 is covered fully
`below.
`Frame 110 is generally of a continuous hollow cylindrical
`form and is substantially rectangular in cross section.
`Although frame 110 is completely covered and sealed from
`biological ?uids in each implanted aortic valve 10, the
`material selected for frame 110 is non-corrosive, fatigue
`resistant, and substantially biologically inert. As such, frame
`110 may be made from stainless steel or a carbon based
`material such as pyrolytic carbon on a graphite substrate.
`However, frame 110 may be made from materials having
`comparable weight, biocompatibility, ?exibility, and
`strength characteristics similar to the materials of preference
`within the scope of this invention.
`To provide support for stent 30 and the three superior
`circumferential edges of cusps 40, 50, and 60 of valve lea?et
`apparatus 20, frame 110 comprises three inverted “U”
`shaped stanchions 112, 114, and 116. In this ?rst illustrated
`embodiment, each of the stanchions 112, 114, and 116 are
`identical. For this reason, only stanchion 112 will be
`
`15
`
`20
`
`25
`
`35
`
`45
`
`55
`
`65
`
`8
`described in detail with the understanding the description of
`stanchion 112 applies equally to stanchions 114 and 116.
`Inverted “U” shaped stanchion 112 comprises a superior
`edge 20, an inner surface 122, an inferior edge 124, and an
`outer surface 126, as best seen in FIG. 2. At the highest
`point, inverted “U” shaped stanchion 112 comprises an apex
`128 superiorly disposed on edge 120. Similarly, stanchion
`114 comprises an apex 128" and stanchion 116 comprises a
`stanchion 128‘. Disposed below apex 128 and inferior to
`superior edge 120, frame 110 comprises a plurality of holes,
`generally numbered 130, disposed between surfaces 122 and
`124. Holes 130 are provided for the purpose of sewing
`corresponding margins of the heart valve lea?et apparatus
`20 to stent 30. For this reason, superior edge 120 is arcuately
`formed to follow a path which provides a margin superior to
`holes. Thus, edge 120 arcuately follows a distally descend
`ing path from apex 128 to a most inferiorly disposed medial
`point 132 where stanchion 112 extends to circumferentially
`smoothly connect to stanchion 116. Edge 120 similarly
`descends distally from apex 128 on the other side of stan
`chion 112 to an inferiorly disposed medial point 134 extend
`ing circumferentially to connect smoothly to stanchion 114.
`Inferior edge 124 comprises an apex 138 disposed imme
`diately below apex 128 and offset from apex 128 to provide
`inferiorly disposed support for attaching marginally dis
`posed portions of heart valve lea?et apparatus 20 associated
`with cusps 40 and 50, as is described in detail hereafter. As
`seen in FIG. 2, proximally disposed in a margin of frame 110
`above inferior edge 124, are a plurality of holes, generally
`numbered 140, disposed between surfaces 122 and 126.
`Holes 140 comprise a second set of holes inferior to holes
`130 through which heart valve lea?et apparatus 20 is also
`sewingly or otherwise attached to stent 30. While attachment
`of the heart valve lea?et apparatus 20 to stent 30 is described
`to be accomplished by sewing, one who is skilled in the art
`would understand that other methods of attachment, such as
`by a plastic connector or by fusing parts together through the
`holes, generally numbered 130 and 140, are within the scope
`of the invention.
`As seen in FIG. 2, superior edge 120 and inferior edge 124
`combine to describe the inverted “U” shape of stanchion
`112. Flexibility of the material used to make frame 110 in
`combination with the inferior opening of the inverted “U” of
`stanchion 112 provides a frame capable of annular deformity
`and slight perimetric expansion. Such deformity and expan
`sion permits the frame to compliantly respond to expansion
`and contraction of the native valve ori?ce of the beating
`heart in which aortic valve 10 is implanted to reduce beat by
`beat stress on aortic valve 10 anchoring sutures and thereby
`reduce the likelihood of eventual valve dehiscence. Also, to
`reduce the likelihood of valve dehiscence, the mass of frame
`110 is reduced by excising material which is essentially
`unnecessary for strength, but which adds to the weight of
`frame 110 and therefore of stent 30. Therefor, windows 142,
`144, and 146 are formed as best seen in FIG. 2.
`Reference is now made to FIGS. 3-5 wherein the steps
`used to cover at least a large measure of frame 110 are seen.
`As seen in FIG. 3, the covering is a cylindrical seamless
`section 150 of material which is essentially biologically
`inert. A material such as GORTEXTM, a polytetra?uoroeth
`ylene (PTFE) composite is preferable, however materials
`such as continuous knit a commercially available, medical
`grade DACRONTM velour such as a knitted velour polyester
`(polyethylene glycol terephthalate) or other materials having
`biochemically inert and compatible characteristics similar to
`those of PI‘FE derivatives may be used. All GORTEXTM
`materials referenced hereafter are products of and available
`
`Medtronic, Medtronic Vascular,
`and Medtronic CoreValve
`Exhibit 1007 - Page 10
`
`

`

`5,469,868
`
`20
`
`9
`from W. L. Gore and Associates, Inc., Medical Products
`Division, PO. Box 900, Flagstaff, Ariz. 86002. Section 150
`is of substantially the same exterior diametrical size as the
`interior diameter of frame and comprises a length which
`exceeds twice the height of stanchions 112, 114, and 116 for
`reasons which are described in detail hereafter. Section 150
`comprises a top edge 152, a bottom edge 154, an inside
`surface 155, and an outside surface 155'.
`As a ?rst step in covering frame 110