A SAFE DRIVING METHOD FOR A CONTINUOUS-FLOW VAD USING MOTOR CURRENT PULSATILITY -EVALUATION IN DIFFERENT-SIZED ANIMALS

Abstract

We originated a ‘safe’ driving method for a continuous flow VAD, which prevents ventricular collapse and regurgitation, without incorporating specific sensors, by detecting 2 specific points within the pulsatile motor current. We previously reported that our method could regulate pump flow in a preload-dependent manner, as per Starling's law. In this study, we examined whether the ability to detect these specific points was dependent on animal size. Beagle dogs (n= 8, 10.2 – 17.2 kg), piglets (n= 3, 31.0 – 46 .0 kg) and goats (n= 4, 34.5 – 42.0 kg) underwent left-ventricular bypass from the left ventricle to the descending aorta, using a mixed-flow pump. Two specific points were searched for, using the 'index of current amplitude' from the motor current waveforms: the turning point (t-point) from partial to total assistancepand the point of initiation of ventricular collapse. Despite variations in body weight over the species examined in this study, the specific points could be detected in all cases but one goat, in which total assistance was not achieved because of inappropriate inlet cannula location. Pump flow at t-point of about 75 ml/min/kg was almost equal to the cardiac output of the animals before pumping commenced, and no regurgitant element was evident in the flow waveform. We concluded that our method was effective for safely driving a continuous-flow VAD in animals of various sizes.