The BJUT-II VAD (which was previously called the intra-aorta pump) is a novel left ventricular assist device (LVAD) with a special structure and connection with the native heart. The hemodynamic effect of the phase difference of this pump on the cardiovascular system is still unclear. In this work, seven speed waveforms, whose phase differences vary from 0° to 180°, are used to evaluate the hemodynamic effect of change in phase difference on the cardiovascular system. The external work (EW), equivalent afterload (EAL), pulsatile ratio (PR), and mean aortic pressure during diastolic period (MAPD) are chosen to evaluate the hemodynamic state of the circulatory system. Mathematical study results show that the support levels generated by the BJUT-II VAD under various phase differences are comparable. In contrast, EW, EAL, PR, and MAPD are significantly affected by change in phase difference. It is found that EW reaches its maximum value when the phase difference equals 30°. Similarly, EAL declines with increasing phase difference. PR reaches its maximum value when the phase difference is at 60°. In addition, MAPD decreases with increasing phase difference and then achieves its maximum value at 30°. To obtain comprehensive evaluation of the hemodynamic effects of phase difference on the cardiovascular system, a weight detection algorithm (WDA) whose output indicates the hemodynamic state of the circulatory system is also designed, with EW, PR, and MAPD chosen as the inputs. The minimum value of the output of the WDA indicates the optimal hemodynamic state and optimal phase difference for the BJUT-II VAD. According to the output of the WDA, 30° is considered to be the optimal phase difference for the BJUT-II VAD.
Keywords: BJUT-II ventricular assist device; Equivalent afterload; External work; Hemodynamics; Phase difference; Pulsatility ratio.
Copyright © 2014 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.