The improved Björk-Shiley tilting disc valve prosthesis.

The Björk-Shiley valve has been improved in three respects: (1) Increased strength by making the inlet strut an integral part of the orifice ring and doubling its cross-section area; (2) Improved hydrodynamics; (3) Elimination of the area of stagnant and low flow behind the disc. By utilizing a convexo-concave disc and by moving the pivot point downstream, the disc in open position is moved further out of the orifice ring. The flow through the smaller hole is thus increased by 40%. A significant clearance is obtained between the disc and the valve ring in open position. 234 of these valves have been inserted and followed-up for a maximum period of two years with excellent results.