Original Article

Thrombus Formation in Centrifugal Pumps

^* Address correspondence to: Bruce Morin, Cardiopulmonary Perfusion Resources, LTD, 4078 Bush Hill Ct., Crown Point, IN 46307

Abstract

Three centrifugal flow pumps; the Biomedicus BP80, the Sarns Delphin and the Aries Lifestream 2100, were evaluated in vitro to determine each pump's individual tendencies for thrombus formation. Thrombogenic surfaces in the circuit were minimized by using heparin coated tubing and connectors. The centrifugal pumps, which were not heparin bonded, were placed in line in a circuit which consisted of a venous reservoir, a heat exchanger and a centrifugal pump.

One trial was performed for each of the three pumps by priming the circuits with approximately 500 ml of fresh heparinized bovine plasma. Protamine sulfate was titrated in slowly to decrease the activated clotting time (ACT) from an initial level of >600 seconds back to baseline. The thrombus formation was documented on videotape using a strobe lamp flashed at a frequency compatible with the pump's rpm.

Thrombus formation was observed in each of the centrifugal pumps we evaluated. We have determined that the centrifugal pump is a potential source of thrombus formation and it may result in an increased morbidity or mortality for the patient when used for cardiopulmonary bypass or ventricular assist without adequate systemic heparinization.