Overview of Veno-Arterial Extracorporeal Membrane Oxygenation (VA-ECMO) Support for the Management of Cardiogenic Shock

Abstract

Cardiogenic shock accounts for ~100,000 annual hospital admissions in the United States. Despite improvements in medical management strategies, in-hospital mortality remains unacceptably high. Multiple mechanical circulatory support devices have been developed with the aim to provide hemodynamic support and to improve outcomes in this population. Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is the most advanced temporary life support system that is unique in that it provides immediate and complete hemodynamic support as well as concomitant gas exchange. In this review, we discuss the fundamental concepts and hemodynamic aspects of VA-ECMO support in patients with cardiogenic shock of various etiologies. In addition, we review the common indications, contraindications and complications associated with VA-ECMO use.

Keywords: VA-ECMO complications; VA-ECMO indications; cardiogenic shock; extracorporeal membrane oxygenation; mechanical circulatory support.

Figure 1

Veno-arterial extracorporeal cardio-membrane oxygenation (VA-ECMO) circuit and North South syndrome. A venous cannula is inserted into the superior vena cava/right atrium to drain deoxygenated blood by the extracorporeal pump (1). After passing through the “membrane lung (2),” oxygenated blood is returned into the iliac artery through the arterial cannula. Proximal (venous) and distal (arterial) sensors monitor circuit flow (3). A continuous hemodialysis machine may be spliced into the venous limb of the circuit if needed to provide renal replacement therapy (4). In situations when the left ventricle recovers pulsatility yet the pulmonary gas exchange remains inadequate, deoxygenated blood may be ejected into the ascending aorta. As the fully oxygenated retrograde flow provided by the ECMO circuit collides with the deoxygenated blood in the aorta, a mixing cloud forms (*). Its location is determined by the native cardiac function and the level of competing ECMO support. If undetected, ischemia of the organs perfused by the anterograde flow may develop.