Development Progress of the University of Pittsburgh Streamliner

A magnetically-suspended mixed-flow blood pump is being developed a a permanently implantable ventricular assist device. The pump impeller i supported by hybrid passive radial and active axial magnetic bearings, resulting in an energy-efficient suspension system. The internal fluid dynamics of the Streamliner pump were optimized with a combined computational and experimental fluid dynamics approach. In-vitro hydrodynamic experiments with a water/glycerol solution demonstrate hydraulic efficiency of 28% and a broad operating range. In-vitro evaluation with bovine blood demonstrated very low hemolysis (N.I.H. 0.0015±0.0010 g/100L) at 7000 RPM, 6 lpm against 100 mmHg. Shock testing demonstrated ability to withstand a peak acceleration of 8g along al three axes. An in-vivo experiment was conducted with a titanium-nitrid coated pump connected between the LV apex and the descending aorta i an 87 kg calf. The study was electively terminated after 34 days. The pum operated at a mean flow of 5.9 liters/minute and a mean arterial pressur of 96 mmHg. Mean plasma free hemoglobin was 7.3±3.9 mg/dl and platelet count was normal. Hematological and blood chemistry indicate normal organ function throughout the course of the study. Post morte examination revealed there were no pathological changes in the animal with the exception of renal infarctions. All blood-contacting surfaces of the pump were found to be free of thrombus with the exception of crevices at the inflow cannula junction and between the leading edge of th stator blades and housing. These results were quite encouraging, but emphasize the need to eliminate all sources of steps, grooves, and crevice in the manufacturing process.