Venting during venoarterial extracorporeal membrane oxygenation

Abstract

Cardiogenic shock and cardiac arrest contribute pre-dominantly to mortality in acute cardiovascular care. Here, veno-arterial extracorporeal membrane oxygenation (VA-ECMO) has emerged as an established therapeutic option for patients suffering from these life-threatening entities. VA-ECMO provides temporary circulatory support until causative treatments are effective and enables recovery or serves as a bridging strategy to surgical ventricular assist devices, heart transplantation or decision-making. However, in-hospital mortality rate in this treatment population is still around 60%. In the recently published ARREST trial, VA-ECMO treatment lowered mortality rate in patients with ongoing cardiac arrest due to therapy refractory ventricular fibrillation compared to standard advanced cardiac life support in selected patients. Whether VA-ECMO can reduce mortality compared to standard of care in cardiogenic shock has to be evaluated in the ongoing prospective randomized studies EURO-SHOCK (NCT03813134) and ECLS-SHOCK (NCT03637205). As an innate drawback of VA-ECMO treatment, the retrograde aortic flow could lead to an elevation of left ventricular (LV) afterload, increase in LV filling pressure, mitral regurgitation, and elevated left atrial pressure. This may compromise myocardial function and recovery, pulmonary hemodynamics—possibly with concomitant pulmonary congestion and even lung failure—and contribute to poor outcomes in a relevant proportion of treated patients. To overcome these detrimental effects, a multitude of venting strategies are currently engaged for both preventive and emergent unloading. This review aims to provide a comprehensive and structured synopsis of existing venting modalities and their specific hemodynamic characteristics. We discuss in detail the available data on outcome categories and complication rates related to the respective venting option. Graphical abstract

Adjusted mortality of extracorporeal membrane oxygenation for acute myocardial infarction patients in cardiogenic shock

“…Various unloading techniques, such as concomitant use of IABP, impella, and left atrium or left pulmonary artery venting, have been described for the prevention of volume overloading to the left ventricle. [30] IABP can Table 1 (Continued ) Medicine also be a good option for an unloading technique during ECMO support. VA-ECMO could increase afterload, which would result in pulmonary edema.…”

Scrutinizing the Role of Venoarterial Extracorporeal Membrane Oxygenation: Has Clinical Practice Outpaced the Evidence?

“…Impella support during VA-ECMO has been shown to decrease LV end-diastolic diameter, 1,72 pulmonary capillary wedge pressure, 73 and systolic pulmonary artery pressure, 74 as well, and may, in theory, be effective in preventing lung injury, LV dilatation, and stasis, and supporting myocardial recovery, as well. 47,57,70,75 The main downsides of the Impella are a considerable rate of hemolysis and access site complications, the necessity of surgical implantation for larger Impella pumps (Impella 5.0 and 5.5), and substantial device costs. 47 At present, there is no randomized evidence informing outcomes of the "ECMELLA" concept (VA-ECMO+Impella) in CS (Table S4).…”

Cardiogenic Shock: Searching for a Better Lifeboat

“… 4 Reports of catastrophic left ventricular clot formation, pulmonary vascular congestion, and poor rates of recovery of left ventricular function have led to hybrid strategies, including VA‐ECLS and the addition of a “venting” strategy to reduce left ventricular pressure overload and enhance myocardial recovery. 5 , 6 , 7 This is analogous to a leaky lifeboat, which is sustained by throwing water overboard as quickly as it accumulates. Such strategies vary from use of the IABP to reduce afterload intermittently, to implantation of an Impella device, as well as use of balloon atrial septostomy to “decompress” the left heart (which is pressurized by VA‐ECLS).…”

“…Such strategies vary from use of the IABP to reduce afterload intermittently, to implantation of an Impella device, as well as use of balloon atrial septostomy to “decompress” the left heart (which is pressurized by VA‐ECLS). 5 , 8 , 9…”

“…The use of the Impella series of catheters to “unload” the left ventricle is based on sound logic and machine simulations of hemodynamics, and it is reinforced by case series and experience. 5 , 8 , 9 , 10 , 11 However, given the relative dearth of trial data in CS, there have not been any prospective trials to support the use of VA‐ECLS in patients with CS (with or without “unloading/venting”). Therefore, we are left to look at registry data for clues to the ultimate truth.…”