Combined aortic and mitral valve replacement. A randomized study comparing the Björk-Shiley and Lillehei-Kaster disc valve.

The present series was comprised of 48 patients, 25 of whom received the Björk-Shiley (B-S) and 23 the Lillehei-Kaster (L-K) disc valves. The 2 groups were comparable with regard to age, and to preoperative clinical and hemodynamic status. The randomized selection was carried out at the beginning of the operation. The total mortality in the B-S and L-K groups was 16% and 21% respectively. All surviving patients were restudied 13-40 months (mean 27) after surgery. Late thromboembolic complications occurred in 2 patients with B-S and in 3 with L-K valves, all leaving minor neurological sequelae. There was a relatively large number of patients in the L-K group with unmeasurable values of haptoglobin, indicating more hemolysis in these patients. However, the difference was not statistically significant. The clinical and hemodynamic status was improved in both groups. In the aortic position a significant gradient was found across the L-K valve, while no significant obstruction in the flow was found in the B-S valve. The pulmonary arteriolar resistance was significantly higher in patients with B-S than in those with L-K valves. Otherwise, there was no significant differences between the 2 groups, neither with regard to clinical nor to hemodynamic status.