Left Ventricular Mechanical Support with Impella Provides More Ventricular Unloading in Heart Failure Than Extracorporeal Membrane Oxygenation

The Impella microaxial-flow pump can directly unload left ventricle (LV) in cases of acute heart failure. Extracorporeal membrane oxygenation (ECMO) is widely used for circulatory support. Although the clinical effectiveness of ECMO has been demonstrated, insufficient LV loading reduction may not be advantageous for myocardial recovery. The objective was to compare ventricular loading reduction and reversibility of ventricular fibrillation (VF) with either Impella or ECMO. Six dogs were used. Extracorporeal membrane oxygenation was established by the femoral artery and right atrium. The Impella LD was inserted in LV by the ascending aorta. An acute failing heart was created by sequential coronary artery ligations. Pressure-volume (PV) relationships were acquired without a device and with ECMO or Impella. When VF occurred, direct cardioversion was performed while supported by either ECMO or Impella. The PV area, which is a measure of ventricular unloading and is correlated with myocardial oxygen consumption, decreased more with Impella than with ECMO. Successful defibrillation was achieved more effectively while under Impella support. Superior ventricular unloading with the Impella device may provide higher recovery potential to damaged hearts than ECMO and may have a significant impact not only on intensive care of patients with heart failure but also on resuscitation. ASAIO Journal 2011; 57: 169-176.