[In vitro hydrodynamic characteristics of heart valves in tricuspid position]

At present there are many problems concerning the choice of heart valve for cardiac valve replacement in the tricuspid position. Thus, we devised an attachment head for the prosthetic valve in order to evaluate the hemodynamic characteristics of four clinically-available mechanical prosthetic valves and two xenografts in the pulsatile circulation system in the tricuspid position. Six artificial cardiac valves were used in this experiment; St. Jude Medical (SJM), Starr Edwards ball (S-E), monostrut Björk Shiley (B-S), Omnicarbon, Carpentier Edwards (CE) supraannular, CE-pericardial whose tissue annulus diameter was 27 mm. The experimental instrument similar to that of Umezu et al, was prepared to determine the mean pressure gradient, output and calculated orifice area of each valve. Since many of the patients who must undergo tricuspid valve replacement have severe multi valvular diseases with atrial fibrillation, we experimented also under the condition of atrial fibrillation. At sinus rhythm under pulsation flow, no significant difference was shown in cardiac output between the various valves, but pressure gradient was higher with xenografts than with mechanical prostheses, and the SJM valve showed the widest efficient valve orifice area. The reduction rate of the efficient valve orifice area from sinus rhythm to atrial fibrillation was about 10% in the SJM valve, which was better rate than other heart valves. We observed significant differences in cardiac output, pressure gradient and efficient orifice area at sinus and atrial fibrillation rhythm. (p less than 0.01).