Controversies in extracorporeal membrane oxygenation: Immediate versus watchful waiting for venoarterial extracorporeal membrane oxygenation venting

Transaortic Catheter Venting for Left Ventricular Unloading in Veno-Arterial Extracorporeal Life Support: A Porcine Cardiogenic Shock Model

Background and Objectives: Left ventricle (LV) overloading during veno-arterial (VA) extracorporeal membrane oxygenation (ECMO) is detrimental to myocardial recovery. To determine whether LV unloading using transaortic catheter venting (TACV) is effective, we analyzed the effect of TACV in a human-sized porcine model. Materials and Methods: Hypoxic biventricular dysfunction was induced in 11 pigs using femoro-femoral VA-ECMO and custom-made TACV catheters in the LV through the common carotid artery. Hemodynamic conditions were then simulated. The TACV was either opened or closed under a controlled ECMO flow. Conversely, the ECMO flow was adjusted, varying from 1 L to 4 L, with and without TACV; 2115 observations were collected. Results: In comparing observations without TACV (TACV-) and with TACV (TACV+), the change in left ventricular end-diastolic pressure (LVEDP) after TACV application was -1.2 mmHg (p < 0.001). In the linear regression model, the reduction in LVEDP was maximized when the baseline LVEDP and ECMO flow were higher. When escalating the ECMO flow in the respective settings of TACV- and TACV+, the rise in LVEDP was significantly lower in TACV+. Conclusions: TACV decreased LVEDP; this effect was more prominent when ECMO flow and baseline LVEDP were higher. These findings suggest that TACV might support LV recovery through effective unloading, even when ECMO flow is high.

Early unloading and clinical outcomes in patients with fulminant myocarditis undergoing VA-ECMO: results of a multicenter retrospective study

INTRODUCTION AND OBJECTIVES

Although venoarterial extracorporeal membrane oxygenation (VA-ECMO) provides effective cardiocirculatory support in patients with fulminant myocarditis, the most effective timing of venting is uncertain. We aimed to investigate the benefit of early venting among patients who underwent VA-ECMO for fulminant myocarditis.

METHODS

Among 841 patients with acute myocarditis from 7 hospitals in the Republic of Korea, 217 patients with fulminant myocarditis who underwent VA-ECMO were included in this analysis. The patients were categorized into 2 groups: an early unloading group that underwent venting within 24hours of ECMO insertion, and the no or delayed unloading group. The primary outcome was a composite of death, cardiac replacement, or cardiovascular rehospitalization.

RESULTS

Among 217 patients, 56 underwent early venting, 54 underwent delayed venting, and 107 did not undergo venting. On spline curves in 110 patients who underwent venting, rapid deterioration was observed as the timing of venting was delayed. The incidence of the primary outcome was lower in the early venting group than in the no or delayed unloading group (37.5% vs 58.4%; HR, 0.491; 95%CI, 0.279-0.863; P=.014). Among patients not experiencing the primary outcome within 6 months, clinical outcomes were similar after 6 months (P=.375).

CONCLUSIONS

Early left heart unloading within 24hours of ECMO insertion is associated with a lower risk of a composite of death, cardiac replacement therapy, and cardiovascular rehospitalization in patients with fulminant myocarditis undergoing VA-ECMO. Registered at ClinicalTrials.gov (NCT05933902).

Impact of Left Ventricular Unloading on Outcome of Heart Transplant Bridging With Extracorporeal Membrane Oxygenation Support in New Allocation Policy

BACKGROUND

The new heart allocation policy places veno-arterial extracorporeal membrane oxygenation (VA-ECMO)-supported heart transplant (HT) candidates at the highest priority status. Despite increasing evidence supporting left ventricular (LV) unloading during VA-ECMO, the effect of LV unloading on transplant outcomes following bridging to HT with VA-ECMO remains unknown.

METHODS AND RESULTS

From October 18, 2018 to March 21, 2023, 624 patients on VA-ECMO at the time of HT were identified in the United Network for Organ Sharing database and were divided into 2 groups: VA-ECMO alone (N=384) versus VA-ECMO with LV unloading (N=240). Subanalysis was performed in the LV unloading group: Impella (N=106) versus intra-aortic balloon pump (N=134). Recipient age was younger in the VA-ECMO alone group (48 versus 53 years, P=0.018), as was donor age (VA-ECMO alone, 29 years versus LV unloading, 32 years, P=0.041). One-year survival was comparable between groups (VA-ECMO alone, 88.0±1.8% versus LV unloading, 90.4±2.1%; P=0.92). Multivariable Cox hazard model showed LV unloading was not associated with posttransplant mortality after HT (hazard ratio, 0.92; P=0.70). Different LV unloading methods had similar 1-year survival (intra-aortic balloon pump, 89.2±3.0% versus Impella, 92.4±2.8%; P=0.65). Posttransplant survival was comparable between different Impella versions (Impella 2.5, versus Impella CP, versus Impella 5.0, versus Impella 5.5).

CONCLUSIONS

Under the current allocation policy, LV unloading did not impact waitlist outcome and posttransplant survival in patients bridged to HT with VA-ECMO, nor did mode of LV unloading. This highlights the importance of a tailored approach in HT candidates on VA-ECMO, where routine LV unloading may not be universally necessary.

Modelling and Simulation of the Combined Use of IABP and Impella as a Rescue Procedure in Cardiogenic Shock: An Alternative for Non-Transplant Centres?

The treatment of critically ill patients remains an evolving and controversial issue. Mechanical circulatory support through a percutaneous approach for the management of cardiogenic shock has taken place in recent years. The combined use of IABP and the Impella 2.5 device may have a role to play for this group of patients. A simulation approach may help with a quantitative assessment of the achievable degree of assistance. In this paper, we analyse the interaction between the Impella 2.5 pump applied as the LVAD and IABP using the numerical simulator of the cardiovascular system developed in our laboratory. Starting with pathological conditions reproduced using research data, the simulations were performed by setting different rotational speeds for the LVAD and driving the IABP in full mode (1:1) or partial mode (1:2, 1:3 and 1:4). The effects induced by drug administration during the assistance were also simulated. The haemodynamic parameters under investigation were aa follows: mean aortic pressure, systolic and diastolic aortic pressure, mean pulmonary arterial pressure, mean left and right atrial pressure, cardiac output, cardiac index, left and right ventricular end-systolic volume, left ventricular end-diastolic volume and mean coronary blood flow. The energetic variables considered in this study were as follows: left and right ventricular external work and left and right atrial pressure-volume area. The outcome of our simulations shows that the combined use of IABP and Impella 2.5 achieves adequate support in the acute phase of cardiogenic shock compared to each standalone device. This would allow further stabilisation and transfer to a transplant centre should the escalation of treatment be required.