Background: The purpose of this study was to evaluate the effects of left ventricle unloading by the Jarvik 2000 axial-flow pump on coronary blood flow.

Methods: The Jarvik 2000 pump was implanted in 10 calves using partial cardiopulmonary bypass. Left ventricular (LV) hemodynamics, coronary blood flow (CBF), and myocardial oxygen consumption (MVO₂) were measured when the pump was operating at 8,000, 10,000 and 12,000 rpm, and the results were compared with the baseline (pump off, 0 rpm) values. Echocardiography was performed at increasing speeds to evaluate left and right ventricular dimensions and aortic valve opening.

Results: No surgical or device-related complications occurred. The Jarvik 2000 significantly increased the mean and diastolic aortic pressures and resulted in narrowed pulse pressure at speeds above 10,000 rpm (p<0.05). Left ventricular end-systolic and end-diastolic pressures, pulmonary capillary wedge pressure, and LV dimensions gradually decreased at higher pump speeds. Although coronary blood flow and myocardial oxygen consumption decreased at increasing pump speeds (p<0.05), the ratio of CBF to MVO₂ remained between 0.18 and 0.20 in all calves throughout the study. Right heart pressures were not affected by increases in pump speeds and remained close to the baseline values.

Conclusion: We conclude that left ventricle unloading with Jarvik 2000 pump does not compromise LV functions and affect CBF/MVO₂ ratio.

Keywords : Blood flow velocity; blood pressure; coronary circulation; echocardiography; heart-assist devices; heart failure, congestive; myocardium; oxygen consumption; prosthesis implantation; vascular resistance; ventricular function, left