Hydrodynamic Advantages and Disadvantages of Mechanical Bileaflet Valves and Tilting Disc Valves No. 29

Abstract

In order to determine the effectiveness of mechanical heart valves two different types of mechanical heart valves, three tilting disc valves (BS–SD, BS–CCD, BS–M) and two bileaflet valves (St Jude Medical, Duromedics) with the same size of annulus diameter d_A = 29 mm have been investigated in the mitral position of a mock circulation under pulsatile flow conditions. Flow, pressure and orifice area have been measured. Insufficiency, mean orifice area, discharge coefficient, performance index, and efficiency index have been calculated.

The investigated tilting disc valves show smaller reflux volume and smaller insufficiency when comparing with the bileaflet valves. The bileaflet valves show higher values of orifice areas—that is to say smaller pressure drops—than the tilting disc valves. The St Jude Medical shows the biggest orifice areas, but also the highest reflux volume and insufficiency. Insufficiency of the Duromedics is slightly higher than that of the tilting disc valves. The orifice area of the Duromedics is bigger than that of the tilting disc valves and smaller than that of the St Jude Medical. The different pivot and the different profile of the disc of the BS–CCD and the BS–M are responsible for the more constant behaviour of the opening of these tilting disc valves when comparing with the BS–SD. Though the bileaflet valves show the better efficiency index, none of the valve types is superior in all hydrodynamic criteria. Both valve types, the bileaflet valves and the tilting disc valves, show different hydrodynamic advantages and disadvantages.