The index of motor current amplitude has feasibility in control for continuous flow pumps and evaluation of left ventricular function

The index of motor current amplitude (ICA) has feasibility in continuous-fl ow ventricular assist device control. It can demonstrate the safe range of pump speed, which exists between the starting point of total assistance (t- point) and the starting point of sucking (s-point). The objective of this s tudy was to investigate how the ICA characteristic curve changes with each condition of contractility, preload, and afterload changes. We changed prel oad, afterload, and contractility of closed-mock circulation and plotted th e change of the ICA value against pump speed. Then the shift of ICA charact eristic curve against the change of each condition was considered. When pre load increased, ICA characteristic curves showed the expansion of a safe ra nge. When afterload increased, ICA characteristic curves were shifted to th e high rotation side, slightly narrowing a safe range. When contractility i ncreased, ICA characteristic curves showed the shift of a convex above to n arrowing of a safe range. As these shift patterns were observed even when t he driving conditions of a circuit changed, reproducibility was checked. Un derstanding the feature of a shift pattern of ICA characteristic curves cor rectly, a possibility that change of the heart function could be predicted by change of ICA value and a possibility for a flexible control method base d on ICA, according to hemodynamic state, were suggested.