| Abstract: | More than 10 years of clinical experience with 1,800 consecutive valve replacements with the Bj?rk-Shiley tilting disc valve were focused on improving its durability, flow dynamics, thromboresistance, and in vivo functional control. Although the original Delrin disc functions excellently after 10 years in the human circulation, the durability of the prosthetic valve was further prolonged by the introduction of pyrolytic carbon as disc material. The opening mechanism was also reinforced by integrating the bearing struts with the valve ring. No other presently available heart valve prosthesis shows such a low resistance to flow for a given tissue diameter. The disc was equipped with a ring-shaped radiopaque marker that permitted noninvasive functional control. The 5 year survival rates were 82% after aortic, 66% after mitral, and 66% after mitral and aortic valve replacements, including the operative mortality rates. The incidence of systemic emboli was 0.7% per year after aortic, 4.2% per year after mitral, and 2.2% per year after mitral and aortic valve replacements with anticoagulation treatment. The incidence of obstruction by thrombosis was 0.3% per year for aortic, 1.3% per year for mitral, and 2.3% per year tricuspid prostheses. The new convex-concave model decreases the stagnation zone behind the disc, decreases emboli from 4.2% to 1.2% per year after mitral valve replacement, and has a lower gradient. |
