Abstract: A method and apparatus for proof testing an assembled mechanical heart valve prosthesis having a valve body and at least one movable occluder wherein at least one of the components has a surface of nonmetallic crystalline material, such as pyrocarbon, in which microcrack growth may occur. The assembled valve prosthesis is subjected to fluid loading with the occluder in the closed position so as to create omnidirectional pressure of at least 20 psig therewithin on the downstream side of the occluder. During fluid loading of the assembled valve, acoustic monitoring is carried out using a transducer to detect sounds that are indicative of crack nucleation and/or incremental crack extension, based upon a predetermined fail-pass criterion. Any valve prosthesis wherein sounds of a greater magnitude are detected is rejected.

Abstract: A prosthetic heart valve is shown which incorporates a valve body design and leaflet pivot arrangements that minimize turbulence and shear stresses having a tendency to generate thrombosis. A valve body having an axially curved entrance that is smoothly joined to a generally cylindrical body of extended axial length provides excellent fluid flow characteristics when combined with leaflets that can assume orientations perfectly aligned with the downstream flow of blood. By constructing such a pyrocarbon valve body which receives a metal ring at an appropriate location, suture rings that permit the tissue annulus to directly contact the exterior surface of the cylindrical valve body are accommodated.

Abstract: A prosthetic heart valve is shown which incorporates a valve body design and leaflet pivot arrangements that minimize turbulence and shear stresses having a tendency to generate thrombosis. A valve body having an axially curved entrance that is smoothly joined to a generally cylindrical body of extended axial length provides excellent fluid flow characteristics when combined with leaflets that can assume orientations perfectly aligned with the downstream flow of blood. By constructing such a pyrocarbon valve body which receives a metal ring at an appropriate location, suture rings that permit the tissue annulus to directly contact the exterior surface of the cylindrical valve body are accommodated.

Abstract: Pure unalloyed pyrocarbons having wear resistance suitable for use in pyrocarbon-coated heart valve components and having mechanical properties, such as flexural strength and toughness, superior to commercial silicon-alloyed pyrocarbons are deposited in fluidized bed coaters. Coating conditions are carefully controlled so as to maintain a precise bed size within a defined coating enclosure which will assure a substantially constant surface deposition temperature that in turn assures deposition of homogenous unalloyed pyrocarbons having these improved mechanical properties.

Abstract: A bileaflet heart valve incorporates a pivot arrangement that minimizes resistance to downstream blood flow in the open position yet has prompt response and therefore minimal regurgitation upon flow reversal. A valve body having an axially curved entrance that smoothly joins a generally cylindrical body of extended axial length provides excellent fluid flow characteristics when combined with leaflets that can assume orientations perfectly aligned with the downstream flow of blood. Identical flat leaflets can assume a parallel orientation in the fully open position during downstream blood flow or can assume other low energy positions. Flat ears, which extend laterally from opposite surfaces of the leaflets, interengage with cavities of unique design having upstream and downstream lobes separated by an intermediate throat portion defined by inward and outward fulcrums.

Abstract: A bileaflet heart valve is shown which incorporates a pivot arrangement that minimizes resistance to downstream blood flow in the open position yet has prompt response and therefore minimal regurgitation upon flow reversal. The valve employs a pair of identical flat leaflets that can assume a precisely parallel orientation in the fully open position at or near peak downstream blood flow or can alternatively assume other low energy positions. As the downstream flow of blood slows near the end of a pumping stroke, downstream displacement of the leaflets results in their prerotation toward the closed position orientation, all being controlled by the interengagement of flat ears, which extend laterally from opposite surfaces of the leaflets, and receiving cavities of unique design. The cavities include upstream and downstream lobes separated by an intermediate throat portion defined by inward and outward fulcrums.

Abstract: Pure unalloyed pyrocarbons having wear resistance suitable for use in pyrocarbon-coated heart valve components and having mechanical properties, such as flexural strength and toughness, superior to commercial silicon-alloyed pyrocarbons are deposited in fluidized bed coaters. Coating conditions are carefully controlled so as to maintain a precise bed size within a defined coating enclosure which will assure a substantially constant surface deposition temperature that in turn assures deposition of homogenous unalloyed pyrocarbons having these improved mechanical properties.

Abstract: Mechanical heart valve prostheses having either a single occluder or a pair of occluders are designed to permit such occluders to assume an open position parallel to the longitudinal axis of the valve passageway. The pivot arrangements are such that an occluder pivots about a constant center or pivot axis substantially offset from the locations where engagement occurs between the occluder and the valve body, whereby prompt smooth pivoting movement toward the closed position is initiated from an open position parallel to the valve centerline. For example, elongated arcuate shoes protruding from lateral edges of the occluders follow arcuate paths of matching complementary curvature defined by grooves in diametrically opposed flat sidewall sections of the valve body.

Abstract: Heart valves are shown which utilize pivot arrangements that create prompt response to flow reversal and minimize resistance to blood flow in the open position. Illustrated are valves having a pair of identical leaflets that can assume an orientation in the fully open position near maximum blood flow rate that is precisely parallel to the centerline of the passageway. The ability of the leaflets to assume a precisely parallel or low energy position in the bloodstream reduces pressure drop across the valve and results in improved flow characteristics. A camming action adjacent the upstream edges of the leaflets in combination with interengagement at downstream locations on the valve body, spaced from the locations where the camming action with said upstream edges occurs, positively guide the leaflets to assure effective closing movement regardless of momentary deviations in the dynamics of the reverse flow of blood through the valve.

Abstract: Bi-leaflet heart valves have valve body contours and pivot arrangements that create quick valve response to flow reversal. Valve members or leaflets, which can have flat or curved inflow and outflow surfaces, are slidably and pivotally mounted in a heart valve body of contoured profile so they can be aligned precisely parallel to blood flow in the open position. The leaflets engage either projections extending radially inward from flat wall sections in the valve body sidewall or grooves in these flat wall sections. The shape and relationship of these interengaging surfaces, together with a centrally directed surge of backflowing blood which results from the strategic location of a pair of downstream recesses in the annular valve body, cooperate to provide prompt closing rotation of the leaflets from a parallel open orientation.

Abstract: Bi-leaflet and single occluder heart valves have improved pivot arrangements that create quick valve response to flow reversal and minimize impact. Valve members or occluders, which have curved inflow and outflow surfaces, are slidably and pivotally mounted in a heart valve body and can be aligned precisely parallel to blood flow in the open position. Lugs on the valve members engage surfaces on projections extending radially inward from flat wall sections in the valve body sidewall, and the shape and relationship of these interengaging surfaces provide prompt initial rotation, low wear and reduced impact upon closing. Laterally directed ears engage the valve body arcuate sidewall and assist in defining the path of closing movement.

Abstract: Bi-leaflet heart valves have improved flow characteristics in their open position as a result of employing valve bodies of elongated axial dimension. By elongating the axial dimension of valve bodies which have straight, smooth interior wall surfaces oriented parallel to the centerline through the valve and to the flow path of blood, and by employing a pair of occluders which have major surfaces that are rectilinear and can assume an orientation that is substantially parallel to the centerline in the open position, a streamlining of blood flow occurs. The pivot arrangements avoid the use of acute angular surface orientations and cause the occluders, although aligned substantially parallel to blood flow in the open position, to promptly pivot toward the closed position upon reversal of blood flow. This streamlining substantially reduces turbulence and results in low head loss, both significant advantages in bi-leaflet heart valve performance.

Abstract: Prosthetic heart valves having a single occluder, or a pair of identical mating occluders, guided in their movement from the open to the closed position by pairs of elongated slots in diametrically opposed flat sidewall sections of the valve body. Each occluder is formed with two ears that protrude from opposite flat side surfaces along the lateral edges thereof. The ears may be frustoconical or hemispherical or the like and are slidingly received in elongated slots which can be straight or arcuate. The main body portions of the occluders have rectilinear surfaces that are aligned parallel to the centerline through the valve in the open position, so as to give low resistance to blood flow. However, when the backflow of blood displaces the occluders upstream, the slot arrangements are such that even though the occluder bodies are parallel, pivoting towards the closed position orientation begins essentially immediately, and the closing movement is of short duration so as to minimize regurgitation.

Abstract: Heart valves, particularly those having two identical leaflets, are shown which utilize improved pivot arrangements that create prompt response to flow reversal and minimize impact at the instant of closing. Illustrated are valves having pairs of leaflets that can assume an orientation in the fully open position that is precisely parallel to the centerline of the passageway, yet which will promptly respond upon blood flow reversal and quickly close to prevent substantial regurgitation. The ability of the leaflets to assume a precisely parallel or low energy position in the bloodstream reduces pressure drop across the valve and results in improved flow characteristics. Prompt closing movement pivoting from a parallel position is effected by creating a camming action adjacent the upstream edges of the leaflets while positively guiding the overall path of leaflet translation and rotation by interengagement at other locations spaced from the upstream edges.

Abstract: Bi-leaflet and single occluder heart valves have improved pivot arrangements that create quick valve response to flow reversal and minimize impact. Valve members or occluders, which are slidably and pivotally mounted in a heart valve body, can be aligned precisely parallel to blood flow in the open position. Lugs on the valve members engage surfaces on projections extending radially inward from flat wall sections in the valve body sidewall, and the shape and relationship of these interengaging surfaces provide prompt initial rotation, low wear and reduced impact upon closing. Laterally directed ears engage the valve body arcuate sidewall and assist in defining the path of closing movement.

Abstract: Bi-leaflet heart valves have improved flow characteristics in their open position as a result of employing valve bodies of elongated axial dimension. By elongating the axial dimension of valve bodies which have straight, smooth interior wall surfaces oriented parallel to the centerline through the valve and to the flow path of blood, and by employing a pair of occluders which have major surfaces that are rectilinear and can assume an orientation that is substantially parallel to the centerline in the open position, a streamlining of blood flow occurs. The pivot arrangements avoid the use of acute angular surface orientations and cause the occluders, although aligned substantially parallel to blood flow in the open position, to promptly pivot toward the closed position upon reversal of blood flow. This streamlining substantially reduces turbulence and results in low head loss, both significant advantages in bi-leaflet heart valve performance.

Abstract: In a dental prosthesis having a post stem, a neck and a head, the stem has a terminal segment at the end opposite the head and an intermediate segment with an uneven surface between the terminal portion and the head. The radial extremities of the uneven surface extend precisely to the contour of a right circular cone tapering in the terminal direction, and the radial extremities of the outer surface of terminal portion extend radially outward beyond the contour of this cone. A socket is drilled into the alveolar bone using a drill bit having the same conical taper that the extremities of the uneven surface follow. The prosthesis is inserted into the socket with some pressure so that the terminal portion deforms the alveolar bone only at the deep end of the socket, locking the prosthesis into the socket and bringing the extremities of the uneven surface into firm surface contact with the wall of the socket.

Abstract: Methods are provided for fully encasing radio-opaque markers in pyrocarbon prosthetic members. Inserts having a pyrolytic carbon portion joined to a radio-opaque marker are affixed to a mandrel surface so that the marker extends thereabove. Pyrocarbon sufficient to encase the marker is deposited on the mandrel, the mandrel is removed, and the deposited layer of pyrocarbon is finished to form the prosthetic member.

Abstract: Multistrand carbon coated sutures comprising a plurality of small diameter fibers having a tensile modulus of at least about 2.times.10.sup.6 psi, and a thin, smooth, adherent, isotropic carbon coating on the substrate fiber having particular properties including a tensile fracture strain of at least about 5%.

Abstract: Artificial vascular and patch grafts comprising a flexible elastic fabric substrate of predetermined shape fabricated from small diameter fiber having a tensile modulus of at least about 2.times.10.sup.6 psi, and a thin, smooth, adherent, isotropic carbon coating on the substrate fiber having particular properties including a tensile fracture strain of at least about 5%.