THE RELATIONSHIP BETWEEN DIASTOLIC PUMP FLOW OF THE CENTRIFUGAL BLOOD PUMP AND THE LEFT VENTRICULAR OUTPUT THROUGH THE AORTIC VALVE

Abstract

Aim: We tried to verify the hypothesis that increases in pump flow during diastole are matched by decreases in left ventrickle output during systole. Methods and materials: Two calves (68 and 130Kg) were implanted with the implantable centrifugal blood pump (EVAHEART, SunMedical Corp. Japan) with LV-Ao bypass and parameters were recorded at different pump speeds under the general anesthesia. Pump inflow and outflow pressure, arterial pressure, pump and pulmonary blood flow, and ECG were recorded on the computer every 5 msec. Additionally, echocardiography was done for one of two calves 30 days after implant. All parameters were separated into systolic and diastolic components and analyzed. Results: The pulmonary flow was the same as the systemic flow and blood pressure did not change during examination (p>0.1). The systemic flow consisted of the pump flow and LV output through the aortic valve. The ratio of the systolic pump flow to the pulmonary flow (51.0%) did not change significantly, at variable pump speeds (p>0.1). The other portions of the systemic flow were shared by the left ventricular output and the pump flow during diastole. When the pump flow increased during diastole there was a corresponding decrease in the left ventricular output. The volume study of echocardio-graphy also showed the same results. Conclusions: These show that the pump diastolic flow may regulate expansion of the left ventricle in diastole.