**Abstract**

Survival to discharge in patients presenting with cardiogenic shock who are managed using extracorporeal membrane oxygenation (ECMO) remains low at ~50%. This speaks to the acuity and severity of individuals being placed on ECMO, as well as the time dependent risk for complications associated with this therapy. Although some patients are able to be weaned from ECMO to either recovery, left ventricular assist device or heart transplantation, other individuals do not survive after device removal, suggesting that current protocols may not be identifying individuals with enough intrinsic cardiac recovery to maintain adequate end-organ perfusion. The decision to wean an individual from ECMO is complex and entails several factors that are dynamic and evolving daily while on full circulatory support. Objective clinical, hemodynamic and biological markers are needed to be controlled prior to trialing device weans but many times the decision relies on clinical experience and intuition. The purpose of this chapter will be to: (1) outline the survival and risks associated with ECMO which encourages early weaning trials and (2) identify patient factors related to either successful weaning or early referral for durable mechanical support or transplant.

**Keywords:** venoarterial ECMO, weaning, cardiac recovery, echocardiography, hemodynamics

#### **1. Introduction**

Cardiogenic shock to date remains associated with a significant mortality (50–80%) even after revascularization [1]. For these patients and in those with other forms of refractory cardiogenic shock or cardiac arrest, circulatory support with the use of venoarterial extracorporeal membrane oxygenation (VA-ECMO) has been utilized to stabilize and improve their survival. Its rapidly expanding use across many centers has favorably altered outcomes in severely critically ill patients and in many instances it serves as a bridge to decision or recovery [2]. However, weaning of VA-ECMO represents a significant challenge depending on the initial indication for its use. Moreover, there is a paucity of data on factors that predict weaning success from VA-ECMO and no clear guidelines to determine which patients will survive after device removal.

With the rapid evolving technology of short term mechanical circulatory support and the increasing number of ECMO use across many centers, there needs to be a clear understanding of the indications, hemodynamic impact, limitations and risks associated with its application to determine who will be a good candidate for device wean and removal.

In this chapter we will review the basic principles of VA-ECMO function, predictors of survival, conditions conducive towards successful weaning and lastly, weaning strategies.
