Variation in Artificial Heart Acceleration and Sound Production with Prosthetic Valve Selection in vitro

Abstract

In an attempt to explore methods to reduce total artificial heart (TAH) acceleration and sound production, in vitro measurements of TAH acceleration and sound were made when using a variety of prosthetic valves in a test ventricle. A miniature, uniaxial, high fidelity accelerometer was glued to the housing of a UTAH-100 left ventricle adjacent to the inflow and outflow ports and parallel to the axis of diaphragm excursion. A miniature, high fidelity contact microphone was glued to the opposite side of the ventricular housing between the inflow and outflow ports. Data was collected over a range of heart rates, ventricular filling volumes and control modes while using tilting disc valves (TDV) and polymer trileaflet valves (PTV). For both valve types, the peak systolic acceleration impulse was lower (approximately equal to 50%) when the ventricle was fully rather than partially filled and the peak diastolic acceleration impulse was lower (approximately equal to 50%) when the ventricle was fully rather than partially ejected. The magnitude of the acceleration with PTVs was approximately equal to 20x less than the TDVs (0.5 to 2.2 g vs. 10 to 49g). The magnitude of the sound production was also considerably less with the PTVs (28 to 49 db vs. 50 to 64 db). Diastolic acceleration and sound production was approximately twice the systolic value for the TDVs; the reserse was true for PTV sound production. These data demonstrate the substantial reduction in TAH impulse acceleration and sound production by selecting PTVs over TDSs. With PTVs, the TAH impulse acceleration is the same as the natural heart. Consequently, this ability to lower TAH acceleration and sound production to the level of the natural heart may lead to a reduction in component wear, patient discomfort and other undesirable consequences of TAH implantation.