Long-term survival of experimental calves with a left ventricular assist impeller pump.

An impeller pump has been evaluated chronically in calves as a left ventricular assist device. In a group of 18 calves, three survived approx. 2 months (62, 54 and 46 days, respectively) while earlier calves survived less than 14 days. The termination of the experiments was due to bearing wear, which resulted in pump failure. The pump delivered nonpulsatile or pulsatile blood flow, according to the heart function. All the haemochemical data remained within normal or acceptable ranges during the experiments. Further improvement is now concentrated on developing a magnetic bearing to solve the problem of bearing wear.