The Sternotomy Hemopump

Abstract

The first generation Hemopump is a VAD based on a catheter mounted intraarterial axial flow blood pump that is placed through the femoral artery. Blood is withdrawn from the left ventricle through a transvalvular inflow cannula and pumped into the aorta. Clinical trials have demonstrated hemodynamic efficacy, improved survival, and low hemolysis in cardiogenic shock. The incidence of non-insertion of the device and fracture of the flexible drive cable limited its utility, however. In addition, some processes used in pilot production could not be adapted to volume manufacturing. A second generation device, the Sternotomy Hemopump, has been developed for insertion through the ascending aorta. Design changes include a shortened inflow cannula, higher flow hydraulics, and a more durable flexible drive cable. In addition, more efficient manufacturing processes were implemented. In a pulsatile mock loop the flow was 5.7 L/min at 100 mmHg. In vivo experiments of up to 2 weeks demonstrated a mean plasma free hemoglobin of 8.7 mg/dl, minimal valve injury, and an acceptable incidence of renal infarction. In vitro endurance demonstrated a 7 day reliability of 99.9% with a 95% confidence. A new clinical trial will evaluate the use of the Sternotomy Hemopump for nonoxygenator support during aorto-coronary artery bypass surgery.