Hemolysis in fresh human blood with a new hemoperfusion pump to prevent myocardial ischemia during coronary angioplasty

A new, 5 ml, piston type hemoperfusion pump, designed to prevent myocardial ischemia during coronary angioplasty, was evaluated in vitro at different flow rates. The driving pressures necessary to achieve the different flow rates and biochemical indicators of hemolysis, were assessed. Fresh human blood was perfused through 2 angioplasty catheter types, one with distal side holes and another catheter type without side holes but with a tapered distal segment. Despite high driving pressures, shear stress > 200 Pa, turbulent flow and the presence of occlusive valves in the pump, hemolysis proved to be minimal. This is most readily explained by the short period of time during which the blood was subjected to mechanical factors that cause hemolysis. Additionally, the volume of the pump, and hence the amount of blood subjected to mechanical hemolysis, was small. The side holes in the catheter caused obstruction by promoting the formation of clots.