Changes in hemodynamics and coronary blood flow during left ventricular assistance with the Hemopump

The Hemopump, a catheter-mounted left ventricular assist device, has been demonstrated to be effective in supporting patients with potentially reversible cardiac failure. The mechanism of recovery of the hearts with this device is not fully understood. The effects of the Hemopump on hemodynamics and coronary blood flow with and without myocardial ischemia and failure have been studied in 8 anesthetized open-chest dogs. Coronary blood flow in the left circumflex artery was assessed with an intracoronary Doppler catheter. Myocardial ischemia was induced by ligation of the left anterior descending and diagonal branches. The effects of maximum support were compared with those of minimum support. The effects of the Hemopump varied according to cardiac function. When cardiac dysfunction was mild, the Hemopump support slightly reduced myocardial O2 demand (assessed by pressure-work index) by volume unloading. When cardiac dysfunction was severe, total bypass was achieved and myocardial O2 demand decreased by 45%, owing to both volume and pressure unloading. Coronary blood flow was incompletely auto-regulated, and the ratio of blood flow to O2 demand increased.