Abstract: Pyrolytic carbon of extremely uniform crystalline characteristics and essentially free of discontinuities is obtained in a fluidized bed coater by creating an asymmetric recirculation of the fluidized bed within the high temperature coating chamber. Through the use of any of a variety of gas injection schemes, fluidizing/coating gas mixtures are injected through the three-dimensionally curved concave bottom surface of the coater to create a pattern where the fluidized bed ascends within about one-half of the volume of the coater and then spills over to become a descending bed in the other half.

Abstract: A prosthetic venous valve having a two-piece housing which includes upstream and downstream sections. The upstream section contains a circular seat against which an occluder comes in sealing contact when the valve is in its closed position. The downstream housing section is shaped so as to prevent escape of the occluder downstream and to halt the reciprocating motion of the occluder in the open position where there is an open pathway past the occluder. A plurality of fins on the interior of the downstream housing section or on the surface of the occluder assure there is a blood flow path downstream past the occluder in the open position. The two-piece construction allows the housing sections to be axially spaced apart so that blood comes in contact with the interior surface of the patient's vein immediately downstream of the upstream section of the housing.

Abstract: A prosthetic heart valve comprising a tubular valve body and a pair of leaflets which pivot, or translate and pivot, between open and closed positions. The valve body is of circular interior cross-section except for a pair of diametrically opposed flat wall sections which contain recesses within which the pivot axes of the leaflets are located. Arcuate edges of the leaflets are irregularly shaped so that a pair of protrusions extend radially outward from an otherwise generally semicircular periphery. The protrusions are strategically located so as to contact the interior surface of the valve body in the closed position at arcuately spaced apart locations which flank the centerline of the leaflet. As a result, contact in the closed position occurs at two spaced apart locations rather than at a single location, and at least a minimum gap is established at the central tip of the leaflet which counteracts potential cavitation, noise and hemolysis.

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 trileaflet heart valve includes a generally annular valve body having an interior wall of nominally circular cross-section into which three wedge-shaped projections radially extend to provide three pairs of flanking flat surfaces between which three leaflets are pivotally supported. The valve body has an outwardly flaring upstream entrance end that, together with the configuration of the leaflets, assures streamlined flow and low transvalvular pressure drop. Wing sections extend laterally in both directions at angles between about 30.degree. and 50.degree. from flat central sections of the leaflets to create V-shaped cross-section leaflet bodies having short flat edge sections along the lateral edges of both wing sections that create a wide open central flow passageway. The three leaflets assume an orientation parallel or nearly parallel to the central axis in full open position.

Abstract: A sewing ring for a heart valve prosthesis to allow the valve to be sutured into operative position in association with a region of a human heart from which a defective valve has been excised. The generally cylindrical exterior surface of a valve body of circular cross-section is provided with either an encircling groove or a protruding annular band. To interconnect with such groove or band, a metal split sleeve is provided which has either a radially inward directed projection or an annular cavity for mating, respectively, with the groove or band of the valve body. A tubular fabric sleeve from which a sewing cuff is constructed is first fitted about the valve body, and a central portion of such fabric sleeve is sandwiched between the split sleeve and the valve body so that it is entrapped and preferably compressed between the interconnecting elements. A continuous locking ring, e.g.

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 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 trileaflet heart valve includes a generally annular valve body having an interior wall of nominally circular cross-section into which 3 wedge-shaped projections radially extend to provide 3 pairs of flanking flat surfaces between which leaflets are pivotally supported and which includes an outwardly flaring upstream entrance end that, together with an elongated axial length, assures streamlined flow and a low transvalvular pressure drop. The leaflets assume an orientation substantially parallel to the central axis in the open position with their swinging movement in the direction of closing being guided by pairs of arcuate ridges and posts which protrude from the flanking flat walls of the projections and which guide the leaflets in a pivoting and translating swinging movement. The downstream ends of the curved ridges are enlarged in cross-section, compared to the upstream ends, and in combination with the posts create stops which determine the desired open position orientation of the three leaflets.

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.