Criteria to select proper valve prosthesis for aortic valve replacement. Comparative assessment of various valve prostheses via continuous wave Doppler echocardiography

Continuous wave Doppler echocardiography was used to measure pressure gradients (PG) across various aortic valve prostheses [St. Jude Medical (SJM) valve: 55 cases; Bjork-Shiley (B-S) valve: 18 cases; Lillehei-Kaster (L-K) valve: 25 cases; and Omniscience (O-S) valve: 49 cases]. Disc-opening angles of the L-K and O-S valves were measured via cineradiography. Pressure gradient across the SJM valve tended to be low. Increase in pressure gradients during exercise tended to be greater in the small valves. There was a significant correlation between the valve area index (VAI) and pressure gradients in the SJM valve (PG = 85.3 - 40.2 x VAI, r = -0.71, p < 0.005) and in the B-S valve (PG = 64.6 - 23.3 x VAI, r = -0.89, p < 0.025). To keep pressure gradients below 20 mmHg, SJM valve 23 and B-S valve 25 should be selected for patients with a body surface area of 1.3-1.7 m². In the L-K and O-S valves, there was no significant correlation between VAI and PG, likely because the disc-opening angles of these valves were suboptimal-averaging 57° in the L-K valve and 47° in the O-S valve. None of the patients with SJM or B-S valves had pressure gradients of 50 mmHg or above. However, pressure gradients exceeded 50 mmHg in 7 cases with the L-K valve (28%) and 10 with the O-S valve (20%), suggesting the necessity of careful follow-up in patients with these prostheses.