Development of a mechanical circulatory model during diastolic phase for the evaluation of the prosthetic valve function

In order to evaluate the function of prosthetic heart valve at mitral position a mechanical circulatory model, which is designed to simulate the inflow characteristics during diastole, has been developed. Anatomically identical designed silastic left atrium(LA) and rubber left ventricle(LV) were driven by pneumatic pressure, a timing of which were basically determined on referable to the physiological data. After several trials, the authors could achieve physiologically identical inflow velocity pattern with two velocity peaks: a rapid filling peak (0.6m/sec) at early diastole and subsequent peak (0.5m/sec) by the LA contraction. However, following problems were indicated. 1) There was no increase in the stroke volume by the contraction of the LA. 2) Higher end diastolic pressure (23mmHg) was measured. As a result of modifications including a readjustment of the LV compliance (1 → 3mL/mmHg) and an incorporation of a larger valve (φ25 → φ29), above problems are successfully settled down.