Evaluation of various mechanical heart values in the mitral and aortic positions

To evaluate the function of various types of mechanical heart valves (Björk-Shiley = BS, Medtronic Hall = MH, St. Jude Medical = SJM, Duromedics = DM), hemodynamic studies were performed in 236 patients with valve replacement in addition to the evaluation of the clinical results. In 144 patients with mitral valve replacement including patients with double valve replacement, the degree of the postoperative improvements of clinical symptoms and hemodynamics were similar in patients with BS, DM and MH valves. There was a tendency for the effective orifice area calculated from pressure-half time obtained by continuous-wave Doppler (CWD) echocardiography to be larger in MH or DM valves than in BS valve of the same size on the average. In 115 patients with aortic valve replacement including patients with double valve replacement, there was no significant difference in the degree of postoperative reduction of the left ventricular hypertrophy among the patients with BS, MH and SJM valves. The mean value of the pressure gradient (PG) across the valve at rest obtained by CWD was less than 20 mmHg in each type of valve without significant difference among the valves. PG well correlated with cardiac output (CO) in each type and size of valve, and the rate of increase in PG with the increase in CO was smaller in the larger-sized valve of the same type and also smaller in MH valve than in BS valve of the same size. The frequency of valve-related complications was extremely low in each type of valve except for a higher incidence of occult hemolysis in SJM and DM valves. Overall, there were no significant differences in the clinical results among the patients with valvular prostheses examined. However, MH valve had advantages in hemodynamics and a lower incidence of hemolysis.