The estimation of cardiac function from the rotary blood pump

The rotary blood pump is implanted as a bridge to cardiac transplantation. Mechanical, histological, and biochemical improvements have been described in patients after implantation of left ventricular assist devices (LVADs). Thus, the rotary blood pump might be used as a bridge to recovery of myocar dial function. However, unlike a pulsatile pump, the rotary blood pump cann ot be stopped to estimate cardiac function: if the rotary blood pump stops, backflow will occur. In this study, a new method that can estimate cardiac function without pump stop was examined. Six pigs were the subjects of thi s acute study. The pump was implanted as an LVAD: the inlet cannula was ins erted into the left ventricle, and the outlet cannula was inserted into the ascending aorta. The motor speed was regulated at a pump flow rate of 0 L/ min at diastolic phase. Then, the relationship between the dp/dt of left ve ntricular pressure and external stroke work of actuator was examined. This method was studied at normal, hyperdynamic, and heart-failure conditions. T here was a high positive correlation between the dp/dt of left ventricular pressure and external stroke work of actuator. This method is useful and si mple to estimate cardiac function without pump stop.