The impact of ECMO lower limb cannulation on the aortic flow features under differential blood perfusion conditions

The purpose of this study is to investigate the impact of veno-arterial (VA) ECMO cannulation on hemodynamic distribution and organ perfusion within aorta under differential blood perfusion conditions. The total blood flow volume supplied by failure heart and ECMO keep constant, flow volume ratio of heart output (FVR-HO) increases from 0% to 100% and correspondingly flow volume ratio of ECMO (FVR-ECMO) decreases from 100% to 0%. The flow patterns within aorta, wall shear stress (WSS), oscillatory shear index (OSI), relative retention time (RRT) were analyzed. The locations of oxygenated and de-oxygenated blood mixing region (BMR) was influenced by FVR-HO. With FVR-HO increasing, BMR moves from proximal to distal side of heart. When FVR-HO was 0%, oxygenated blood supplied by ECMO completely perfuses the aortic vessels. High WSS appears in the iliac artery and abdominal aorta vessel walls closed to cannula position. When FVR-HO was in the range of 10%–30%, the BMR was in aortic arch. The higher OSI and RRT were exhibited in ascending aorta and aorta arch. When FVR-HO was 40% and 50%, the BMR was in ventral trunk for systolic period and in aortic arch for diastolic period. The higher OSI and RRT regions enlarge and metastasize to the descending aorta. When FVR-HO was larger than 50%, the BMR was in the downstream region of the renal artery. Of note, when FVR-HO increases from 0% to 100%, the flow ratios in the two renal arteries change from significant different to be closed at systolic period. Peripheral VA-ECMO with various perfusion levels from cardiac output and ECMO has significant effect on aortic flow surrounding. Partial recovery of heart function can impel BMR moves from proximal to distal side of the heart, which may lead to inadequate supply of oxygenated blood to the upper limb and cephalic vessels.