The primary aim of this chapter is to elucidate the utilisation of extracorporeal life support (ECLS) in both the immediate management of patients failing to separate from cardiopulmonary bypass (CPB) during cardiac surgery, and those presenting with poor cardiac output postcardiotomy despite pharmacological support. The application of ECLS in the presentation of cardiogenic shock prior to cardiac surgery as a means of patient optimisation and improving post-surgical outcomes will also be explored. Various forms of temporary mechanical circulatory support (MCS) are available in such contexts including veno-arterial extracorporeal membrane oxygenation (VA ECMO), left ventricular assist devices (LVAD), right ventricular assist devices (RVAD) and biventricular assist devices (BiVAD). The differential characteristics of such variations of MCS are an important consideration in the treatment strategy of postcardiotomy failure, with various configurations offered depending upon patient physiology. Through appropriate patient selection, ECLS type and adherence to certain clinical management strategies, satisfactory outcomes can be achieved in this otherwise very high-risk patient cohort.