Hemodynamic influence of tilting disc valve type on pump performance with the NIPRO-ventricular assist device.

The NIPRO-ventricular assist device (NIPRO-VAD) is an external pulsatile flow pump. Formerly, Sorin Carbocast, a monoleaflet tilting disc valve (SC valve), was used at the inlet/outlet parts of the pump, but Medtronic Hall (MH valve) is now used. We studied the differences in performance among pumps with different artificial valves. Six NIPRO pumps with SC valves and six with MH valves were examined using mock circuits. The systolic flow of the pump was measured with the ultrasonic flowmeter by changing the systolic fraction. Six patients wearing the NIPRO-VAD underwent periodic pump exchange from a pump with an SC valve to the one with an MH valve. The pump blood flow was measured at pre- and post-pump exchanges using an ultrasonic flowmeter. Blood pressure, serum LDH and AST levels were also compared before and after the pump exchange. Blood flow was significantly increased by using the NIPRO-VAD with the MH valve as compared to the SC valve in vitro. Under the same drive conditions pump flow tended to increase in six patients. No difference was found in patients' blood pressure, serum LDH or AST levels when using the SC or MH valve. From these results, the hemodynamic influence on patients due to replacement of the SC valve with the MH valve in the NIPRO-VAD is considered to be insignificant.