Development of the Valvo 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 implanted. The objective of this study was to show the feasibility of using the Valvo pump, an axial flow pump implanted at the heart valve position, in such cases. The Valvo pump consists of an impeller and a motor. The motor is waterproofed with a ferrofluidic seal. A blood flow of 5 L/min was obtained at a pressure difference of 13.3 kPa (100 mm Hg) at 7,000 rpm. The normalized 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 the ferrofluidic seal was 37.5 kPa in a static condition and 26.3 kPa at 10,000 rpm. The seal exhibited no leaks for 41+ days against 20.0 kPa. The results showed that the Valvo pump can maintain systemic circulation with an acceptable level of hemolysis.