Development of mechanical heart valves: past, present and future.

Aortic valve replacement with Bjork-Shiley tilting disc valves in 1753 patients gave a 15 year actuarial survival of 54%. Better results were obtained in narrow aortic roots and in pure aortic stenosis than in pure aortic insufficiency. Anti-coagulation was necessary. Bleeding was the most common complication and the most common valve related cause of death. With the monostrut, no valve thrombosis nor mechanical failure was encountered during five years and a low gradient of 11 mmHg and an effective orifice area of 1.4 cm2 was obtained in cases with a 21 mm valve. Mitral valve replacement with 810 Bjork-Shiley valves gave a 15 year actuarial survival of 51%. Most complications such as embolism, valve thrombosis, reoperations and deaths have the highest incidences during the first postoperative year. Anticoagulation related bleeding continued at a constant rate. The convexo-concave valve decreased the incidence of valve thrombosis significantly without any increase in bleeding complications but was complicated by some strut fractures, especially among the 70 degrees convexo-concave valves. With the monostrut Bjork-Shiley valve the risk of strut fracture was eliminated and valve thrombosis has not occurred during the first five years in patients properly anticoagulated at the Karolinska Hospital, Stockholm, Sweden.