Cardiovascular mechanical support

Abstract

Cardiovascular mechanical support includes the use of devices such as the intra-aortic balloon pump (IABP), extracorporeal membrane oxygenation (ECMO) and ventricular assist devices (VADs). These are used in cardiogenic shock (CS) as a bridge to decision (BTD), bridge to transplantation (BTT) or destination therapy (DT). CS is associated with significant morbidity and mortality.¹ It is a state of low cardiac output associated with hypotension and end-organ hypoperfusion. It includes a systolic blood pressure (SBP) < 90 mmHg or the requirement of vasopressor support to maintain an SBP of at least 90 mmHg, and some signs of end-organ hypoperfusion such as altered mental state, oliguria and a rising lactate.² Other advanced haemodynamic parameters include a cardiac index (CI) < 1.8 l/min/m² without support or < 2.2 l/min/m² with support and an elevated left ventricular enddiastolic pressure (LVEDP) > 18 mmHg.² Maximal medical therapy may no longer be seen as the end point for refractory circulatory shock, especially in well-resourced settings.³ The goal of mechanical circulatory support (MCS) is to move blood from an insufficient ventricle into the aorta or pulmonary artery with the aim of restoring cardiac output.⁴ MCS can be achieved with either short-term devices that are placed temporarily or long-term devices. It is not without complications and these need to be managed by a multidisciplinary team. The Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profiles are used to stratify patients with heart failure into the New York Heart Association (NYHA) functional class III or class IV into one of seven distinct profiles. Based on this profile, a practitioner is able to reasonably gauge how quickly to intervene in terms of placement of a mechanical circulatory device from hours or days to months. The American College of Cardiology/American Heart Association (ACC/AHA) guidelines recommend MCS as a class I therapy as BTT.⁵