When should we use extracorporeal membrane oxygenation in cardiogenic shock?

We read the study of Chen et al. with interest. ¹ Postcardiotomy cardiogenic shock (PCS) is a rare but highly fatal complication of open heart surgery. ² Inotropic agents and intraaortic balloon pump (IABP) which decreases left ventricle afterload and increases coronary perfusion are leading choice of treatment modalities. Short-term ventricular support systems can be needed when these modalities are not sufficient. In this point, it is crucial to decide which ventricular support system to use. As in the study of Chen et al., extracorporeal membrane oxygenation (ECMO), which can be quickly and percutaneously inserted, is a common choice. However, we claim that this decision is quite inappropriate. Because basic principle of ventricular support system is either to decrease afterload like IABP or allowing cardiac function recovery by helping the ventricle to empty its stroke volume like ECMO or Levitronix Centrimag. In general, the main reason of ventricular insufficiency is myocyte damage caused by ischemia. In order to reverse this, tension of ventricular wall should be decreased by helping ventricle to empty its stroke volume. ³ In the light of this knowledge, if the main pathology in PCS is left ventricular insufficiency, it is certain that veno-arterial ECMO won’t be useful. Right ventricular venting is achieved by the inflow cannula of ECMO, which has no effect on left cardiac chambers. Moreover, the outflow cannula worsens the situation by increasing afterload of left ventricle. If PCS is caused by right ventricular insufficiency, veno-arterial ECMO is the good fit for the job. In this point, we have a question to Chen et al., Can the cause of PCS be right ventricular insufficiency for the living population in their study? We think that sharing the knowledge about this question will add value to the authors’ study.