Long-term results with the Björk-Shiley tilting disk valve in aortic valvular disease.

The construction of the Björk-Shiley prosthesis, with its nonoverlapping tilting disk, provides an optimal orifice area in relation to tissue diameter. The transprosthetic forward flow is central and mainly laminar. The resistance to blood flow remains low with increasing cardiac output during exercise, even when the smaller sizes of the prosthesis are used for implantation in narrow aortic roots. Mechanical crushing of erythrocytes is minimized by the nonoverlapping closing mechanism, and the resulting regurgitation is negligible. The in vivo durability of the prosthesis is excellent and thromboembolism does not occur as long as dicoumarol treatment is effective. In aortic valvular disease, an effective unloading of the left ventricle was obtained at rest and during exercise after aortic valve replacement. The resulting hemodynamic improvement correlated with a reduction in cardiomegaly, increase in physical working capacity and relief of distressing symptoms. Clinical improvement was maintained for up to five years.