**2. Incidence of complications and ECMO configuration**

VA-ECMO currently represents the most effective minimally invasive circulatory support system. VA-ECMO has evolved and can now be placed quickly at the bedside, in the medical unit, or in the cardiac intensive care unit. It provides oxygenation, it is the best option in the setting of associated lung injury, it can be placed peripherally (without thoracotomy), and it is the only percutaneous option for biventricular support. It may provide sufficient support to enable adequate tissue perfusion even in cardiac arrest, and it is a suitable device for acute resuscitation of a patient in shock, even if mortality for cardiogenic shock did not significantly change and is still ranging between 50 and 70% [17].

Moreover, many publications have disclosed a dramatic burden of complications using percutaneous VA-ECMO leading to higher costs and ethical discussions on the right clinical settings for its clinical adoption [9, 18–20].

Looking critically at the landscape of effects and complications of different configurations of mechanical circulatory support and specifically of VA-ECMO emerges the importance to select the right device and the right VA-ECMO's configuration to warrant the best outcome. The crucial factor in selecting the device and the VA-ECMO's configuration is the amount of flow needed to restore organ function. Venous oxygen saturation has been indicated by many authors as a good goal to direct VA-ECMO perfusion [21].

Percutaneous VA-ECMO appears fitted to restore peripheral flows when the patient experiences a moderate reduction of cardiac output. When the patient needs higher flows, the risk of pulmonary edema and left ventricular distention increases [22], and additional cares may be necessary to unload the left ventricle and eventually to restore pulmonary function after pulmonary edema [23–25].

Although a beneficial effect on peripheral perfusion/circulation has been demonstrated with VA-ECMO implantation in patients affected by cardiogenic shock, there is a potential for increasing loading conditions into the left ventricle potentially compromising transition to myocardial recovery. Contemporary VA-ECMO systems are increasingly being used with a wide spectrum of configurations.
