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: 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 method of making a prosthetic heart valve having an occluder which is supported to pivot between open and closed positions in an annular valve body made of pyrocarbon or a pyrocarbon-coated substrate. The valve body contains diametrically opposed pivot supports formed on the interior surface thereof and is distended by subjecting it to diametrically opposed compressive forces of a nature which place extensive exterior regions of the valve body in compression while increasing the distance between the pivot supports. After the occluder is installed in the distended annular valve body, removal of the opposed compressive forces permits the valve body to return to an unstressed, generally circular configuration with the occluder operatively secured between the pivot supports. These forces are applied using flexible, inextensible cables or resilient pressure pads.

Abstract: A particle feeding device and method for fluidized bed coaters that has no moving parts. It preferably provides for constant flow of purge gas into the fluidized bed coater and has a feedback control means for monitoring and precisely controlling the flow of particles into the coater. The particle feeding device includes a supply of granular material in communication with a generally horizontal passageway and a delivery conduit for feeding granular material into a desired location, such as a fluidized bed coater. The amount of granular material remaining in the supply is periodically determined and pulses of gas are periodically discharged through said generally horizontal passageway so as to blow granular material into said delivery conduit in a manner so as to feed the precise amount of granular material for predetermined periods of time.

Abstract: A coating-fluidizing gas supply system for a flat-bottom fluidized bed coater that maintains a high degree of uniform fluidization of levitated particles for a long enough time period to coat medical-device components. The coating-fluidizing gas supply system prevents premature pyrolysis of the coating component of the gas from plugging gas-distributor holes of a flat plate at the bottom of a flat-bottom fluidized bed coater, by directing multiple gas streams uniformly against the entire undersurface of the flat gas-distributor plate, creating an overall cooling-effect on the gas-distributor plate which prevents clogging.

Abstract: Precise control of pyrocarbon being coated upon an object in a fluidized particle bed is achieved by monitoring the weight change of the fluidized particle bed over a period of time. Measurement of such weight change is truly representative of bed size in such a coater, which is a most important factor in achieving the desired characteristics of the pyrocarbon being deposited. By monitoring the bed size by repeatedly determining such changes in the weight, compensating adjustments are made by either adding additional particles to the bed or by changing the rate at which particles are withdrawn so that precise coating characteristics are achieved, and coatings can be deposited within very close thickness tolerances.

Abstract: A "closed-loop" moisture control system for use in vibratory mass finishing systems. A substantially constant amount of a grinding and/or polishing slurry is maintained in a finishing reservoir of the vibratory mass finishing system by controlling the amount of such fluid flowing from a supply reservoir into the finishing reservoir, and/or the amount of such fluid flowing from the finishing reservoir into a collection reservoir. In operation, a total weight of the supply reservoir and its contents, and of the collection reservoir and its contents is monitored and, in the event there is an increase in the total weight, a control means increases the amount of polishing fluid flowing from the supply reservoir into the finishing reservoir, and/or decreases the amount of polishing fluid flowing from the finishing reservoir into the collection reservoir.

Abstract: Precise control of pyrocarbon being coated upon an object in a fluidized particle bed is achieved by monitoring the pressure difference between a region above the bed and a region in the lower portion of or just below the bed. Measurement of such pressure differential has been found to be truly representative of bed size in such a coater, and bed size is recognized to be a most important factor in achieving the desired characteristics of the substance being deposited. By adjusting bed size in response to changes in the pressure difference being monitored, a substantially constant bed size is readily achieved; alternatively, the pressure difference can be caused to gradually change in accord with a predetermined program. In either instance, adjustments are effected by adding additional particles to the bed or by changing the rate at which particles are withdrawn, and precise coating characteristics, e.g. thicknesses within very close tolerances, are achievable.

Abstract: Pyrolytic carbon products are manufactured so as to have improved structural properties. Pyrolytic carbon is deposited on a substrate in a fluidized bed of small particles at a temperature of about 1200.degree. to about 1400.degree. C., and after cooling to ambient temperature, the pyrolytic carbon is machined to desired physical dimensions for a heart valve component or the like. By heating such pyrolytic carbon structures in an inert gas atmosphere to a temperature in the range of about 1000.degree.-1500.degree. C. for at least about one hour following machining, it is found that stresses created in the pyrolytic carbon as a result of the machining are relieved without adverse effect to mechanical properties of the pyrocarbon, resulting in components having greater structural integrity.

Abstract: A heart valve holder is provided for holding a heart valve prothesis including an orifice ring having an aperture with a circumferential surface, comprising: a body having a longitudinal axis; a first lever section having a first insertion end and resiliently attached to the body along a first flexure region having a first flexure axis for selectively engaging the heart valve prosthesis; and a second lever section having a second insertion end and resiliently attached to the body along a second flexure region having a second flexure axis parallel to the first flexure axis for selectively engaging the heart valve prosthesis. The body and the first and second lever sections include receiving means for receiving a flexible tensile member to secure engagement of the first and second lever sections to the heart valve prosthesis by flexing the first and second flexure regions so that the first and second insertion ends abut the circumferential surface of the aperture.

Abstract: A suture ring is provided for supporting a heart valve prosthesis having a valve body with an outer circumferential surface and an annular groove formed in the surface, and includes: a stiffening ring, having first and second ends, mounted in surrounding relationship about the valve body at the annular groove of the valve body, the stiffening ring including a tapered outer surface section; a resilient ring positioned about the outer circumferential surface of the body proximate the first end of the stiffening ring; a fabric tube, having a mesh weave body and first and second ends, covering the stiffening ring and the resilient ring, and interposed between the resilient ring and the stiffening ring; a first fastener band frictionally engaging the fabric tube between the first fastener band and the outer circumferential surface of the valve body proximate to the first end of the stiffening ring; a second fastener band frictionally engaging the fabric tube between the outer circumferential surface of the valve b

Abstract: Disclosed is a heart valve of the pivotal bi-leaflet or single occluder type having improved washing characteristics in the region of the support arrangement. The leaflets include cylindrical, or other circular cross-sectional, pivot enlargements at opposite sides of the leaflets, and the valve body includes a number of projections extending inward from its sidewall. The leaflets are mounted in the valve body such that the projections encircle the pivot enlargements at the opposing ends of the leaflets, thereby confining their movement to substantially pivotal rotation between open and closed positions. The projections are spaced from one another, with the region between adjacent projections defining channels through which blood can flow. Some blood flows through these channels both when the valve is in its open position and its closed position, thereby providing blood flow across the pivot enlargements and projections and, thus, minimizing stagnation in the region of the support arrangement.

Abstract: A heart valve of the bi-leaflet or monoleaflet type having improved reductions in drag on blood flow through the fully opened heart valve. The leaflets are pivotally mounted in a heart valve body for movement between closed and opened positions. The leaflets have opposed inflow and outflow surfaces. The inflow surface includes a concave region located downstream of the leaflet pivot axis, and a convex region located downstream of the concave region. The outflow surface of the leaflets is generally convex, at least in that portion directly opposing the concave and convex regions of the inflow surface. The angle of leaflet opening is controlled to values ranging between 70.degree. and about 89.degree..