LONG-TERM EVALUATION OF A NONPULSATILE MECHANICAL CIRCULATORY SUPPORTSYSTEM

Antithrombogenicity of a centrifugal pump (CP) developed in our instit ute is provided by a central balancing hole (BH) in the impeller. A cu rrent CP, the National Cardiovascular Center (NCVC)-2, was ameliorated to improve antithrombogenicity, whereby the BH diameter was widened t o improve self washout flow velocity, and an edge of the thrust bearin g was rounded off to minimize flow separation. Effects of these modifi cations were assessed in a long-term in vivo experiment. The antithrom bogenicity, hemolytic property, and mechanical durability of the NCVC- 2 were investigated in 3 goats. The NCVC-2 was installed paracorporeal ly between the left atrium and the aorta and driven as long as possibl e at rotating speeds of about 2,800 rpm. The NCVC-2 ran for 50, 200, a nd 367+ days. The mean bypass flow rates were 6.8, 5.0, and 5.3 L/min, respectively. Creatinine, blood urea nitrogen (BUN), glutamic-oxaloac etic transaminase (GOT), and glutamic-pyruvic transaminase (GPT) did n ot increase until one week before termination. Plasma free hemoglobin was kept to a level less than 15 mg/dl, except for the last week of th e second case. These results indicate that the NCVC-2 has excellent an tithrombogenicity, an acceptable hemolytic property and the necessary durability for prolonged use.