A ventricular assist system (VAS) developed at the National Cardiovascular Center (NCVC) and produced by Toyobo Company has been clinically evaluated at 32 institutes. The system consists of a pneumatic and diaphragm-type pump, and a control-drive unit with an automatic bypass flow (BF) control system. The VAS was used in 85 adults and 7 children with acute, severe heart failure. Forty-eight patients were weaned from VAS, and 21 were long-term survivors. Heparin was not used when BF was above 2.0 L/min in an adult sized pump, and 0.8 in a pediatric one. Thrombus formation was noticed in the groove around the valve in eight cases, and in the pump in eight. Pump-originated serious complications were not seen. Hematologic and biochemical findings revealed that the VAS did not directly affect the major organs. The control-drive unit, including the automatic BF control system, functioned accurately, with less manpower, securing reliable control over the circulation. Two major causes of death were irreversible heart failure, and multiple organ failure, which resulted from delayed application. In conclusion, the NCVC-type VAS has been found effective and reliable, less thrombogenic, and requiring less manpower for its clinical use.
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