One of the most important physiologic concepts in mechanical circulatory support is that VA-ECMO can simultaneously save the heart and stress the heart.
This apparent paradox stems from the effects of ECMO on left ventricular afterload. When VA-ECMO returns blood to the arterial circulation, aortic pressure rises.
While this improves systemic perfusion, it also creates additional resistance against which the left ventricle must eject.
For a severely failing ventricle, this can become problematic. As afterload increases, left ventricular ejection decreases. End-diastolic pressure rises. Pulmonary venous pressures increase. Pulmonary edema develops.