OBJECTIVES: The aim of this study was to quantify and understand the unloading effect of percutaneous balloon atrial septostomy (BAS) in acute cardiogenic shock (CS) treated with venoarterial (VA) extracorporeal membranous oxygenation (ECMO). BACKGROUND: In CS treated with VA ECMO, increased left ventricular (LV) afterload is observed that commonly interferes with myocardial recovery or even promotes further LV deterioration. Several techniques for LV unloading exist, but the optimal strategy and the actual extent of such procedures have not been fully disclosed. METHODS: In a porcine model (n = 11; weight 56 kg [53-58 kg]), CS was induced by coronary artery balloon occlusion (57 minutes [53-64 minutes]). Then, a step-up VA ECMO protocol (40-80 mL/kg/min) was run before and after percutaneous BAS was performed. LV pressure-volume loops and multiple hemoglobin saturation data were evaluated. The Wilcoxon rank sum test was used to assess individual variable differences. RESULTS: Immediately after BAS while on VA ECMO support, LV work decreased significantly: pressure-volume area, end-diastolic pressure, and stroke volume to ∼78% and end-systolic pressure to ∼86%, while superior vena cava and tissue oximetry did not change. During elevating VA ECMO support (40-80 mL/kg/min) with BAS vs without BAS, we observed 1) significantly less mechanical work increase (122% vs 172%); 2) no end-diastolic volume increase (100% vs 111%); and 3) a considerable increase in end-systolic pressure (134% vs 144%). CONCLUSIONS: In acute CS supported by VA ECMO, atrial septostomy is an effective LV unloading tool. LV pressure is a key component of LV work load, so whenever LV work reduction is a priority, arterial pressure should carefully be titrated low while maintaining organ perfusion.

2nd Department of Medicine Department of Cardiovascular Medicine 1st Faculty of Medicine Charles University and General University Hospital Prague Prague Czech Republic

Cardio Thoracic Surgery Department Heart and Vascular Centre Maastricht University Medical Centre Maastricht the Netherlands

Cardiovascular Research Institute Maastricht Maastricht University Maastricht the Netherlands

Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation IRCCS ISMETT Palermo Italy

Department of Cardiovascular Anesthesia and Intensive Care Unit IRCCS Policlinico San Donato Milan Italy

Department of Physiology 1st Faculty of Medicine Charles University Prague Czech Republic

Intensive Care Unit Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation Mediterranean Institute for Transplantation and Advanced Specialized Therapies Palermo Italy

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