Controllability of 1/R control in non-pulsatile total artificial heart

The role of pulsatility in a total artificial heart (TAH) has been a subject of great debate. Additionally, it is unclear whether, in non-pulsatile TAH, a physiological control method such as 1/R control can keep the animal in physiological condition or not. To examine a controllability of 1/R control in non-pulsatile TAH, non-pulsatile flow mode was introduced to the undulation pump TAH (UPTAH) and the hemodynamic parameters in pulsatile and non-pulsatile flow modes with 1/R control was analyzed. The artificial valve was removed from UPTAH and the goat’s natural heart was replaced with it. The UPTAH was first driven with a pulsatile flow mode and 1/R control was applied within one week after surgery. The pulsatile flow mode was switched to a non-pulsatile flow mode on the day 2 weeks after surgery. General condition did not change before and after the flow mode switching. Cardiac output and arterial pressure changed with the physiological condition of the goat in also non-pulsatile flow mode, which seemed not different from that in pulsatile flow mode. However, the sucking effect of atria was very significant in non-pulsatile mode. Although 1/R control could keep the animal in physiological condition in a non-pulsatile flow mode, non-pulsatile TAH was considered to be inadequate for 1/R control to stabilize atrial pressures in the present circumstances or some pulsatility would be necessary to avoid fatal sucking effect and to ensure sufficient inflow condition.