Hemodynamic properties of the prosthetic valves

-on the relationship between pressure gradient and deflection of valve axis from flow axis-

Abstract

In heart valve replacement, a prosthetic valve is often sutured to the annulus with the deflection angle between valve axis and flow axis, because of the deformed annulus. The present study will describe our results of hemodynamic tests regarding pressure gradient characteristics, as prosthetic valves were tilted with deflection angle.
Three types of prosthetic valves (i. e. Carpentier-Edwards (CE) valve, Björk-Shiley (BS) valve, and St. Jude Medical (SJM) valve) were compared. Pressure gradient of the CE valve was much greater than the other two types of valves. When the right coronary cusp of the CE valve was directed to flow axis (≤20°), the pressure gradient significantly decreased. As the BS valve had a tilting disk, the pressure gradient was significantly changed by the direction (≤20°) of tilting disk. The SJM valve exhibited about 30% lower pressure gradient than the BS valve. In contrast with the other two types of valves, deflection (≤20°) of the SJM valve axis had no effect on pressure gradient. These hemodynamic differences were considered to be caused by their mechanical structures. In conclusion, we have found that fluid dynamic tests with the deflection of valve axis from the flow axis was very useful to evaluate hemodynamic properties of the prosthetic valve.