Shifting the pulsatility by increasing the change in rotational speed for a rotary LVAD using a native heart load...

We have previously developed a native heart load control system for a continuous-flow left ventricular assist device (LVAD) ((EVAHEART^®; Sun Medical) and demonstrated that the rotational speed (RS) in synchronization with the cardiac cycle can alter pulsatility and left ventricular (LV) load under general anesthesia. In this study, we assessed the effects of different levels of increase in RS on pulsatility and LV load in the chronic awake phase. We implanted the EVAHEART via left thoracotomy in 7 normal goats (59.3 ± 4.6 kg). Two weeks after implantation, we examined the effects of co-pulse mode (increased RS in the systolic phase) and counter-pulse mode (increased RS in the diastolic phase), as well as shifting the change in RS from 250 to 500 rpm, and 750 rpm in both modes on pulsatility and LV load. Pulsatility was assessed using pulse pressure and mean dP/dt max of aortic pressure. LV load was assessed using stroke work and left ventricle end-diastolic volume determined from LV pressure-volume loops. In the co-pulse mode, pulsatility values increased as the change in RS increased. By contrast, in the counter-pulse mode, these values decreased as the change in RS increased. LV load increased significantly in the co-pulse mode compared with the counter-pulse mode, but there were no significant differences among the three levels of RS increase in either mode. Increasing RS to varying degrees with our newly developed system could contribute to pulsatility. However, it appeared to have little effect on LV load in normal hearts.