Flow Optimization, Management, and Prevention of LV Distention during VA-ECMO

Abstract

Cardiogenic shock (CS) still carries an unacceptably high mortality (30-60%), despite several therapeutic approaches; the SHOCK II trial questioned the benefit of intra-aortic balloon pump (IABP), while IMPRESS and CULPRIT-SHOCK trials confirmed heterogeneity in disease spectrum and patient selection for acute myocardial infarction-related CS requiring acute mechanical circulatory support (AMCS). The heterogeneity of devices employed as AMCS, including temporary micro-axial flow pumps (Impella), percutaneous bypass (TandemHeart), and extracorporeal life support (VA-ECMO), contributed to the actual dramatic scenario, where CS is defined clinically rather than hemodynamically. To date, the role of VA-ECMO is emerging as rapid strategy to mitigate mortality rates of severe refractory states, despite the lack of data regarding the best practices of management and flows control. VA-ECMO's flow represents the "dose" of treatment and higher flows are less tolerated percutaneously requiring, to prevent deleterious pulmonary edema and ventricular distention, additional approaches such as pulmonary, left atrial, or left ventricular unloading. Any efforts have to be directed to (1) determine adequate management of patients on VA-ECMO, (2) define the safer duration of VA-ECMO support, and (3) establish algorithms and techniques to predict and obtain stable weaning from ECMO or ensure fast transition to durable VAD and/or heart transplant.

Extracorporeal membrane oxygenation and left ventricular unloading: What is the evidence?

“…The available modalities differ in terms of access, extent of LV decompression, complexity, cost, and potential complications ( Table 1 ). 8 , 10 , 11 Thus far, limited comparisons of LV unloading techniques have been published, and more compelling evidence is necessary to determine the superiority or inferiority of any of the various techniques. 12 , 13 , 14 Until such evidence is available, the advantages and disadvantages of each modality should be considered during the decision-making process with attention to potential therapeutic actions after ECMO weaning, patient management, and the presence of mechanical cardiac valves on the left side of the heart ( Figure 1 ).…”

“…These prompt actions might prevent or limit the negative effects of increased LV afterload even when an aggressive LV venting procedure has been implemented before ECMO insertion because of intraoperative implant, failure to wean from cardiopulmonary bypass, or the presence of an intra-aortic balloon pump (IABP) or an Impella device (Abiomed). 11 …”

“…However, negative effects of inotropes in patients with an ongoing or recent myocardial injury has been repeatedly demonstrated, suggesting that such agents should be used judiciously, particularly in the presence of ischemia-induced myocardial damage. 7 , 8 , 11 …”

Left ventricle unloading strategies in ECMO: A single‐center experience

“…ECMO‐generated systemic perfusion increases cardiac afterload which may lead to distention of the left ventricle (LV) and, in cases of profound heart failure, loss of aortic valve opening 9,10 . Possible sequelae of ECMO support on the LV include elevated wall tension, increased myocardial oxygen demand, subendocardial ischemia, dysrhythmias, pulmonary edema, hemostasis, and intracardiac thrombus formation 11 . These effects may impair cardiac recovery or induce catastrophic complications 12,13 …”

“…9,10 Possible sequelae of ECMO support on the LV include elevated wall tension, increased myocardial oxygen demand, subendocardial ischemia, dysrhythmias, pulmonary edema, hemostasis, and intracardiac thrombus formation. 11 These effects may impair cardiac recovery or induce catastrophic complications. 12,13 Medical therapy to maintain forward flow through the LV consists of optimizing preload and afterload and use of inotropes to augment contractility.…”