Abstract: A microporous biocompatible material is formed by preparing a segmented polyether urethane urea solution containing 25%.+-.1.5% solids dissolved in a solvent. The solution has sufficient viscosity to be preshaped and formed into the desired thickness of the finished article, then immediately immersed into a precipitation bath in which the solvent in the solution is miscible for a time interval sufficient to cause the solution to set up into an opaque elastomeric article. The article is immediately removed from the bath, any excess solvent extracted and then dried at a temperature on the order of 35.degree. C. to 70.degree. C. followed by heat treating by annealing for approximately sixty minutes at a temperature at 100.degree. C. to 130.degree. C. The void volume of the membrane solution is controlled to within the 50% to 80% range and the pore size from ca <0.1 to several mms.

Abstract: A prosthetic heart valve is comprised of a low profile valve body defining a central orifice, and an occluder is supported within the valve body to pivot about an eccentric axis which is established by occluder-retaining means in the form of opposed, concave pocket members formed in inwardly projecting planar portions on the inner wall of the valve body. Lateral extensions on the occluder are insertable into the concave pocket members for movement between extreme limits which are established at least in part by limit stop elements directly associated with the pocket members and a rib portion on each of the lateral extensions. The novel and improved arrangement of the occluder retaining means enables a maximum range of movement while minimizing blood stagnation problems as well as stress and wear upon the valve elements.

Abstract: A low profile natural tissue heart valve with a one-piece fabric covering is applied to a stent in a minimum number of steps so that virtually no seams are exposed. The one-piece covering serves also to enclose and mount the sewing ring to avoid separation from the stent. The procedure employed enables use of bovine pericardium united as a single piece to the exterior of the stent and fixed in position in such a way as to avoid prolapsing in use.

Abstract: A prosthetic heart valve has at least one occluder leaflet in which lateral extensions on each leaflet are insertable into generally trapezoidal or triangular depressions formed in diametrically opposed extension walls of the valve body and which depressions both guide and limit the opening and closing movement of each leaflet through predetermined angles of movement.