To systematically evaluate the influence of cannula direction in central venoarterial extracorporeal membrane oxygenation (CVA ECMO) on aortic hemodynamics and oxygen transport through a multiparametric comparative analysis under varying cardiac output conditions.

Computational fluid dynamics methods were applied to analyze five cannula directions (Down, Vertical, Inner, Center, Outer) ECMO models under four cardiac insufficiency conditions. Evaluation parameters included hyperoxic blood distribution, residence time, and scalar shear stress (SSS), oxygen saturation distribution, hemolysis risk (HI), and thrombosis risk.

Both cardiac recovery and cannula direction have a significant effect on the internal environment of aortic blood flow. The recovery of cardiac function can lead to coronary artery hypoxia. The hypoxic blood from the heart and the hyperoxic blood from the ECMO will underwent mixing before reaching the descending aorta and then perfuse to the lower extremities. The cannula directed Down and Vertical improves coronary oxygen supply (oxygen saturation of 93%-98% on ECMO 90% support), but increased aortic wall shear stress (WSS), with mean WSS increase of 27%-54.7%. When cannulas were directed toward the Inner and Center, it significantly reduced the volume of the high SSS region of the vessel and the risk of hemolysis (86% reduction in the volume of the high SSS and 44%-46% reduction in the mean HI when the level of ECMO support was reduced from 80% to 60%) but had a greater adverse impact on coronary oxygen supply (coronary arteries were fully supplied by the heart). The oxygenation of the renal and iliac arteries was less affected by the direction of cannulation, but the risk of thrombosis was significantly increased at the abdominal aortic bifurcation.

The recovery of cardiac function initially results in coronary artery hypoxia, and as the cardiac ejection capacity recovered, it also leads to aortic arch branch vessel hypoxia. Adjusting the direction of cannulation can improve the supply of hyperoxic blood to the coronary arteries (cannula facing Down) or to the branches of the aortic arch (cannula facing Outer). This study provides an important hemodynamic basis for the optimization of ECMO cannulation strategy.