Impact of Left Atrial Decompression on Patient Outcomes During Pediatric Venoarterial Extracorporeal Membrane Oxygenation: A Case-Control Study

Venting during venoarterial extracorporeal membrane oxygenation

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

Extracorporeal Membrane Oxygenation in Congenital Heart Disease

Mechanical circulatory support (MCS) is a key therapy in the management of patients with severe cardiac disease or respiratory failure. There are two major forms of MCS commonly employed in the pediatric population—extracorporeal membrane oxygenation (ECMO) and ventricular assist device (VAD). These modalities have overlapping but distinct roles in the management of pediatric patients with severe cardiopulmonary compromise. The use of ECMO to provide circulatory support arose from the development of the first membrane oxygenator by George Clowes in 1957, and subsequent incorporation into pediatric cardiopulmonary bypass (CPB) by Dorson and colleagues. The first successful application of ECMO in children with congenital heart disease undergoing cardiac surgery was reported by Baffes et al. in 1970. For the ensuing nearly two decades, ECMO was performed sparingly and only in specialized centers with varying degrees of success. The formation of the Extracorporeal Life Support Organization (ELSO) in 1989 allowed for the collation of ECMO-related data across multiple centers for the first time. This facilitated development of consensus guidelines for the use of ECMO in various populations. Coupled with improving ECMO technology, these advances resulted in significant improvements in ECMO utilization, morbidity, and mortality. This article will review the use of ECMO in children with congenital heart disease.

Strategies of left ventricular unloading during VA-ECMO support: a network meta-analysis

BACKGROUND

Left ventricle (LV) unloading during VenoArterial ExtraCorporeal Membrane Oxygenation (VA-ECMO) reduces the risk of LV distention, stagnation and pulmonary congestion resulting from the increased afterload. Lacking direct comparisons between unloading strategies we used network meta-analysis to indirectly compare different unloading approaches.

METHODS

A literature research was performed to include all studies on VA-ECMO reporting data on mechanical LV unloading. The pre-specified outcome was in-hospital death.

RESULTS

Literature search identified 389 studies: 16 were included in the analysis (3930 patients). Two strategies of mechanical LV unloading were compared: afterload reduction (IABP) and preload reduction (Impella pump, right upper pulmonary/trans-septal catheters, LV surgical vents). Any LV unloading strategy was associated with mortality reduction with overall OR = 0.54; 95% CI 0.42-0.70; p < .001. Targeting afterload was associated with reduced mortality (OR = 0.61 95% CI 0.46-0.81; p < .001; I² = 61%), as targeting preload (OR = 0.34 95% CI 0.21-0.55; p < .001; I² = 0%). Significant between group difference was observed (p = .04): to further explore this we performed a network meta-analysis. Indirect comparisons between afterload and preload reduction were estimated. Any unloading technique was confirmed better than none but preload targeting resulted better than afterload targeting.

CONCLUSION

Any unloading strategy in VA-ECMO patients was associated with lower mortality as compared to no-unloading. Preload reduction strategies resulted superior to afterload reduction.