The role of diastolic pump flow in centrifugal blood pump hemodynamics

We tried to verify the hypothesis that increases in pump flow during diasto le are matched by decreases in left ventricular (LV) output during systole. A calf (80 kg) was implanted with an implantable centrifugal blood pump (E VAHEART, SunMedical Technology Research Corp., Nagano, Japan) with left ven tricle to aorta (LV-Ao) bypass, and parameters were recorded at different p ump speeds under general anesthesia. Pump inflow and outflow pressure, arte rial pressure, systemic and pulmonary blood flow, and electrocardiogram (EC G) were recorded on the computer every 5 ms. All parameters were separated into systolic and diastolic components and analyzed. The pulmonary flow was the same as the systemic flow during the study (p > 0.1). Systemic flow co nsisted of pump flow and LV output through the aortic valve. The ratio of s ystolic pump flow to pulmonary flow (51.3%) did not change significantly at variable pump speeds (p > 0.1). The other portions of the systemic flow we re shared by the left ventricular output and the pump flow during diastole. When pump flow increased during diastole, there was a corresponding decrea se in the LV output (Y = -1.068X + 51.462; R<^>(2) = 0.9501). These show th at pump diastolic flow may regulate expansion of the left ventricle in dias tole.