Development of the valve pump: An axial flow pump implanted at the heart valve position

Pulsatile artificial hearts having a relatively large volume are difficult to implant in a small patient, but rotary blood pumps can be easily implant ed. The objective of this study was to show the feasibility of using the Va lve pump, an axial flow pump implanted at the heart valve position, in such cases. The Valve pump consists of an impeller and a motor. The motor is wa terproofed with a ferrofluidic seal. A blood flow of 5 L/min was obtained a t a pressure difference of 13.3 kPa (100 mm Hg) at 7,000 rpm. The normalize d index of hemolysis (NIH) was 0.030 +/- 0.003 (n = 3) for a blood flow of 5 L/min at a pressure difference of 13.3 kPa. The pressure resistance of th e ferrofluidic seal was 37.5 kPa in a static condition and 26.3 kPa at 10,0 00 rpm. The seal exhibited no leaks for 41+ days against 20.0 kPa. The resu lts showed that the Valvo pump can maintain systemic circulation with an ac ceptable level of hemolysis.