EVALUATION OF A CENTRIFUGAL BLOOD PUMP ON HEMOLYSIS AND ON ANTITHROMBOGENICITY IN IN VIVO EXPERIMENTS FOR LONG TERM

Abstract

A Centrifugal Pump (CP) for prolonged use has been developed in our institute. Antithrombogenicity of the initial CP (N1) is provided by aggressive wash-out around the impeller (IM) with a balancing hole (BH) in the center of the IM. But the N1 stopped driving in the 1st, 11th, 22nd and 80th day. The current iteration (N2) was ameliorated to get better antithrombogenicity, where the BH diameter was widened to increase wash-out flow and an edge of a thrust bearing (TB) was rounded off to minimize flow stagnation. Wash-out flow velocity in the BH in the N2 was evaluated to be three second of that in the N1 by the Doppler velocimetry. Less flow stagnation around the TB in the N2 was visualized by light cutting method. In vitro hemolysis tests were performed at a 100mmHg head and a 5L/min flow rate. Allen's hemolytic indexes of the N1, the N2 and the BP-80 were 0.023, 0.008 and 0.008mg/dl, respectively. In vivo antithrombogenicity and hemolytic property in the N2 was investigated by using 3 goats. The N2 was installed paracorporeally between the LA and the Ao. Peroral anticoagulant therapy was conducted with warfarin. The N2 could run for 50, 91+ and 200 days. Plasma free hemoglobin was kept around 8mg/dl.