ECPELLA: Physiology, Configurations, and Evidence Volume 37 | Issue 1 | April 2026
Written by Katy Anderson   

ECPELLA: Physiology, Configurations, and Evidence

by Bhoumesh Patel, MD, MHS
Member, CPC MCS Subcommittee
Hackensack Meridian Health - Jersey Shore University Medical, Neptune, NJ
&
Karuna Puttur Rajkumar, MD, MBBS
Member, CPC Transplant Anesthesia Subcommittee
Wake Forest Baptist, Winston-Salem, NC
&
Lauren Sutherland, MD
Member, CPC MCS Subcommittee
Columbia University Irving Medical Center, New York, NY

Volume 37 | Issue 1 | April 2026

Introduction

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) restores systemic perfusion by providing cardiorespiratory support to patients in cardiogenic shock. However, retrograde aortic flow increases left ventricular (LV) afterload, both with central and peripheral VA-ECMO, predisposing the injured ventricle to distention and impaired myocardial recovery and often leading to pulmonary edema and increased risk of LV or aortic thrombus formation. LV unloading reduces LV pressure and volume, improving coronary perfusion and decreasing myocardial oxygen demand. This can be done through use of the Impella® (Abiomed) percutaneous left ventricular heart pump, an intraaortic balloon pump (IABP), a direct left ventricular vent, or other methods. Use of Impella® with VA-ECMO forms the “ECPELLA” configuration. This article reviews the underlying pathophysiology of LV distention on VA-ECMO, common ECPELLA configurations, and the current evidence supporting this combined strategy.

Physiology

Ventricular Pressure–Volume Loop

The ventricular pressure–volume loop (PVL) illustrates the mechanical profile of the myocardium by integrating intrinsic myocardial properties—such as contractility and diastolic stiffness—with extrinsic vascular determinants including preload and afterload. Myocardial oxygen consumption correlates closely with the pressure–volume area (PVA), the sum of stroke work and potential energy1.

Pressure–Volume Loop on Peripheral VA-ECMO

During cardiogenic shock, VA-ECMO supports systemic perfusion but increases LV afterload through retrograde aortic flow. The compromised ventricle may be unable to overcome this load, resulting in elevated LV end-diastolic pressure (LVEDP), reduced or absent aortic valve opening, and increased left atrial and pulmonary capillary wedge pressures. These changes promote pulmonary edema and worsen gas exchange; in severe cases, intracavitary stasis may lead to thrombus formation1-2.

On the PVL, VA-ECMO shifts the loop upward and rightward along the end-diastolic pressure–volume relationship, creating a taller, narrower loop—indicating reduced stroke volume and increased PVA, thus increasing myocardial oxygen consumption despite improved systemic perfusion1-2.

Effects of LV Unloading

Active LV unloading reverses these undesired hemodynamic changes. The Impella® provides antegrade flow from the LV to the aorta, reducing LV end-diastolic volume (LVEDV), LVEDP, and wall stress while improving coronary perfusion. Unloading eliminates isovolumic phases and produces a triangular, left-shifted PV loop with a markedly reduced PVA2. Unloading differs from simple “venting” by reducing LV work and myocardial oxygen demand as opposed to primarily decreasing filling pressures. 

When to Consider Unloading

Mechanical unloading should be strongly considered when there is evidence of LV distention, including LV or left atrial dilation, diminished arterial pulsatility (i.e., <15–20 mm Hg), absent aortic valve opening, or intracavitary stasis2.

Configurations and Considerations

ECPELLA can be configured in several ways depending on patient anatomy, urgency of support, and institutional resources. Femoral Impella CP® utilized with peripheral VA-ECMO is the most common configuration as it can be placed rapidly utilizing percutaneous deployment, but it carries a higher risk of hemolysis, limb ischemia and vascular injury3. ECPELLA with Impella 5.5® placed into the axillary artery enables higher flow rates for more significant unloading, potentially allowing transition to Impella®-only support while awaiting myocardial recovery or bridge to durable LVAD or transplant3. Impella 5.5® can also be placed into the ascending aorta and used for unloading with central VA-ECMO in patients with post-cardiotomy shock, allowing significant hemodynamic support with LV unloading, but at the expense of increasing bleeding and infection risk4.

Newer approaches such as ipsilateral upper-extremity VA-ECMO with contralateral axillary Impella® and the axillary “Y-chimney” ECMO and Impella® single arterial access configurations provide enhanced mobility and smoother weaning pathways5,6. Hybrid and staged approaches—initiating ECMO first and adding Impella® when LV distention develops—allow clinicians to tailor support as physiology evolves.

Contraindications to use of Impella® include LV thrombus, severe aortic regurgitation, mechanical aortic valves, significant peripheral arterial disease, and aortic pathology. ECPELLA carries risks such as bleeding, hemolysis, renal injury, differential hypoxemia, device malposition, and right-sided heart failure7.

Evidence Summary

Evidence regarding mortality benefit with ECPELLA over VA-ECMO alone remains mixed. Several large retrospective studies and meta-analyses demonstrate improved survival with ECPELLA compared to VA-ECMO alone8-10,15, while others show no significant difference11-13. ECPELLA also carries higher complication rates over VA ECMO alone or with IABP unloading, including bleeding8-11,13-14, hemolysis9-11, limb ischemia8-9,11, and acute kidney injury8-11,13-14. 

Certain subgroups may benefit more from ECPELLA over VA ECMO alone. In acute coronary syndrome there is evidence of benefit with ECPELLA unloading14, but there is conflicting evidence for patients cannulated to ECMO during cardiac arrest (i.e., E-CPR)12,15. Early compared to late ECPELLA unloading has been associated with improved survival8,16. Randomized controlled trials are needed to further elucidate the populations that most benefit from ECPELLA, considering its high risk of complications. 

References

  1. Burkhoff D, Sayer G, Doshi D, et al. Hemodynamics of Mechanical Circulatory Support. J Am Coll Cardiol. 2015 Dec 15;66(23):2663-2674

  2. Ezad SM, Ryan M, Donker DW, et al. Unloading the Left Ventricle in Venoarterial ECMO: In Whom, When, and How? Circulation. 2023 Apr 18;147(16):1237-1250.

  3. Gottula AL, Shaw CR, Milligan, et al. Impella in Transport: Physiology, Mechanics, Complications, and Transport Considerations. Air Med J. 2022 Jan-Feb;41(1):114-127.

  4. Marin-Cuartas M, Wehrmann K, Höbartner M et al. Perioperative temporary mechanical circulatory support with Impella in cardiac surgery patients. J Cardiovasc Surg (Torino). 2022 Apr;63(2):229-236.

  5. Paciotti B, et al. Oper Tech Thorac Cardiovasc Surg. 2024.

  6. Crane JG, Monreal G, Koenig SC et al. Hemodynamic considerations of ipsilateral versus contralateral cannulation with venoarterial extracorporeal membrane oxygenation. JTCVS Open. 2025 Jul 3;27:90-101.

  7. Meani P, Gelsomino S, Natour E et al. Modalities and Effects of Left Ventricle Unloading on Extracorporeal Life support: a Review of the Current Literature. Eur J Heart Fail. 2017 May;19

  8. Schrage B, Becher PM, Bernhardt A et al. Left Ventricular Unloading Is Associated With Lower Mortality in Patients With Cardiogenic Shock Treated With Venoarterial Extracorporeal Membrane Oxygenation: Results From an International, Multicenter Cohort Study. Circulation. 2020 Dec;142(22):2095-2106.

  9. Bhatia K, Jain V, Hendrickson MJ et al. Meta-Analysis Comparing Venoarterial Extracorporeal Membrane Oxygenation With or Without Impella in Patients With Cardiogenic Shock. Am J Cardiol. 2022 Oct 15;181:94-101.

  10. Grandin EW, Nunez JI, Willar B, et al. Mechanical Left Ventricular Unloading in Patients Undergoing Venoarterial Extracorporeal Membrane Oxygenation. J Am Coll Cardiol. 2022 Apr 5;79(13):1239- 1250

  11. Cappannoli L, Galli M, Zito A, et al. Venoarterial extracorporeal membrane oxygenation (VA-ECMO) with vs. without left ventricular unloading by Impella: a systematic review and meta- analysis. Eur Heart J Qual Care Clin Outcomes. 2023 Jun 21;9(4):358-366.

  12. Ling RR, Chen Y, Low CJW et al. Left ventricular unloading during extracorporeal cardiopulmonary resuscitation: a target trial emulation of the ELSO registry. Crit Care. 2025 May 8;29(1):186.

  13. Yeo I, Axman R, Lu DY et al Impella Versus Intra-Aortic Balloon Pump in Patients With Cardiogenic Shock Treated With Venoarterial Extracorporeal Membrane Oxygenation: An Observational Study. J Am Heart Assoc. 2024 Feb 6;13(3):e032607.

  14. Soh BWT, Gracias CS, Dean A, et al. A Systematic Review and Meta-Analysis of the Efficacy and Safety of Combined Mechanical Circulatory Support in Acute Myocardial Infarction Related Cardiogenic Shock. Catheter Cardiovasc Interv. 2025 Feb;105(3):650-661.

  15. Thevathasan T, Füreder L, Fechtner M, et al. Left-Ventricular Unloading With Impella During Refractory Cardiac Arrest Treated With Extracorporeal Cardiopulmonary Resuscitation: A Systematic Review and Meta-Analysis. Crit Care Med. 2024 Mar 1;52(3):464-474. 

  16. Schrage B, Sundermeyer J, Blankenberg S et al. Timing of Active Left Ventricular Unloading in Patients on Venoarterial Extracorporeal Membrane Oxygenation Therapy. JACC Heart Fail. 2023 Mar;11(3):321-330.