Selective coronary hypoxemia during VA-ECMO: limitations of peripheral oxygenation monitoring

Differential hypoxemia during peripheral veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is fundamentally a spatial, not merely temporal, monitoring problem. When native left ventricular ejection coexists with severely impaired pulmonary gas exchange, poorly oxygenated blood may preferentially occupy the aortic root, the most proximal arterial territory, while oxygenated extracorporeal blood returning from a femoral cannula may supply more distal territories. This possibility is not new. Previous computational, experimental, and clinical observations have demonstrated the potential for inadequate myocardial or aortic-root oxygenation during VA-ECMO [ 1 , 2 , 3 ], and contemporary nomenclature of dual circulation has emphasized the limitations of peripheral measurements in defining oxygenation across vascular territories [ 4 ]. Our contribution is therefore not to define a new syndrome, but to frame selective coronary hypoxemia as a clinically relevant monitoring blind spot and to propose an exploratory physiological framework for its recognition and investigation. Importantly, reduced coronary arterial oxygenation, reduced myocardial oxygen delivery, and myocardial ischemia are related but distinct phenomena: myocardial oxygen delivery also depends on coronary blood flow and hemoglobin concentration, whereas ischemia reflects the balance between oxygen supply and myocardial demand.