Hemodynamic studies were performed at rest and during exercise in the 6 patients undergoing mitral valve replacement with porcine xenograft and in the 15 patients undergoing aortic valve replacement with Björk-Shiley tilting disc valve.
(I) Porcine Xenograft:
The mean diastolic gradient elevated from 7.1mmHg at rest to 18.0mmHg during exercise in average, with a wide range of 5.5mmHg to 32.0mmHg. It seemed to be clarified that valve function of porcine xenograft in mitral position varied from valve to valve, with marginal hemodynamic function.
(II) Björk-Shiley tilting disc valve:
There was no pressure gradient across the valve during exercise in the larger than #25 of valve size. On the other hand, the smaller than #23 of valve size showed significant pressure gradient (23.4mmHg at rest; 40.6mmHg during exercise), It is considered to be preferable that these smaller ones should be avoided to be used where feasible.
