Subchronic Use of the St. Jude Centrifugal Pump as a Mechanical Assist Device in Calves

The purpose of this experiment was to study the effects of the St. Jude Lifestream centrifugal pump on hemodynamic and hematologic parameters and the incidence of postmortem findings in a subchronic ex vivo left ventricular assist animal model. Five calves were implanted with the pump as a left ventricular assist device (left atrial to thoracic aorta bypass) and studied for 96 h of continuous pumping under identical conditions. Heparin (100 IU/kg) was administered only in the initial saline pump prime. Throughout the protocol, mean arterial and central venous pressures averaged 102.1 ± 4.6 and 3.4 ± 2.2 mm Hg, respectively. Pump flow was 47.8 ± 8.4 ml/kg/min at a mean pump speed of 1,676.3 ± 106.1 rpm. No clinical abnormalities or mechanical malfunctions attributable to the pump were detected during the 96 h of continuous pumping for each calf. Mean plasma-free hemoglobin after 96 h was 3.9 ± 3.7 u, mol/L (p = 0.337 compared to baseline). At post mortem, renal infarctions were detected in 1 calf. No other pump-associated lesions were detected in any of the other calves. We have concluded that the St. Jude Lifestream centrifugal pump functions reliably during 96 h of continuous left heart bypass in a calf model.