Unloading the left ventricle in veno-arterial ECMO: in whom, when and how?

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) provides cardio-respiratory support to patients in cardiogenic shock. This comes at the cost of increased left ventricular (LV) afterload that can partly be ascribed to retrograde aortic flow causing LV distension, and leads to complications including cardiac thrombi, arrhythmias and pulmonary edema. LV unloading can be achieved by using an additional circulatory support device to mitigate the adverse effects of mechanical overload that may increase the likelihood of myocardial recovery. Observational data suggest that these strategies may improve outcomes but in whom, when and how LV unloading should be employed is unclear; all techniques require balancing of presumed benefits against the known risk of device-related complications. This review will summarize the current evidence regarding LV unloading with VA-ECMO.