Our clinical data of DVR (double artificial valve replacement) with Björk-Shiley valves had informed that a quarter of the patients died of low cardiac output syndrome, the cause of which were analized from a view point of medical-technology.
At first, with the mechanical simulator to cardiovascular system, the characteristics of the single valve of each size as to its response, resistance and leakage flow were made clear. The followings were found;
1) Leakage flow did not show any regularity to the size.
2) Under the same mount of the valvular leakage, response showed positive increment to the size, but resistance negative.
Next, hemodynamics of our simulator under the combinations of each two valvular size were compared one after the other. It was found that the optimal ratio of the double valvular sizes (aortic valve diameter vs. mitral one) was 0.7-0.8 at the maximam flow of the pump. These findings were well correlative to those of the clinical DVR data and the anatomical data, respectively.