|Budget Amount *help
¥12,300,000 (Direct Cost : ¥12,300,000)
Fiscal Year 1999 : ¥4,300,000 (Direct Cost : ¥4,300,000)
Fiscal Year 1998 : ¥3,700,000 (Direct Cost : ¥3,700,000)
Fiscal Year 1997 : ¥4,300,000 (Direct Cost : ¥4,300,000)
Detection and implications of the characteristic points for estimating the assisting condition in a continuous-flow artificial heart -In vitro study-
In this study, we used a specially devised mock circuit consisting of a sac-type pulsatile pump, three reservoirs, and our mixed flow pump (MFP) as a CFAH. The motor current waveform was monitored. The pump speed of the MFP was changed from 2000 rpm to 5000 rpm, We calculated the index of motor current amplitude (ICA), which was obtained, by dividing the amplitude of the motor current by the simultaneous mean value. The ICA plotted against the pump speed (ICA-pump speed relationship) showed several characteristic points: the t-i point, the PR0.7 point, the PR0.5 point, and the maxQ point. The t-i points strongly corresponded to the tuning point from partial to total left heart assistance. When the contractility, afterload, and preload were changed, the pump flow rate at each point changed, depending on the preload like Starling's law. Thes
e data suggest that the assisting status of a CFAH could be estimated by detecting the characteristic points of the ICA-pump speed relationship,
Investigation of the methods of controlling the Biventricular Assist Device with continuous flow pumps.
Using 5 piglets, we set a BVAD with continuous flow pumps via left thoracotomy. Global ischemia was induced for 30 minutes by clamping the base of the ascending aorta. After unclamping the aorta, the analysis of pumping performance was evaluated every an hour for over 6 hours reperfusion. To detect ventricular collapse without any specific sensor, we calculated the index of current amplitude (ICA) from motor current waveforms and simultaneous mean current values, and applied these data when controlling the BVAD. The RVAD speed was determined by setting the target LVAD flow and target ICA value. Using the LVAD target ICA value, we could set the RVAD flow rate to match cardiac function. Using the known pump flow or the pump-flow estimation can be one method of controlling BVAD with continuous flow pumps.