CARD10: Oxygen Delivery in Upper Body Venoarterial Extracorporeal Membrane Oxygenation: A Computational Model

Study: Extracorporeal membrane oxygenation (ECMO) is a vital support modality increasingly relied on to bridge patients with advanced pulmonary disease to lung transplantation. Patients with end-stage lung disease complicated by pulmonary hypertension and concomitant right ventricular dysfunction are particularly challenging to maintain due to combined circulatory and respiratory failure. Upper body venoarterial ECMO, in which the ECMO return cannula is placed in the subclavian artery via a vascular graft to supply oxygenated blood to the proximal aorta and provide circulatory support and unloading the right ventricle, has been employed as a cannulation strategy for this patient population. In an effort to further understanding of the effects of this approach on oxygen delivery in the proximal aorta as a function of relative ECMO support, a model of upper body venoarterial ECMO using patient-specific anatomy and computational fluid dynamic methodology was performed. Methods: A Patient-specific aorta geometry, including coronary arteries and branches of the great vessels, was generated from medical computerized tomography images. Dynamic boundary conditions were applied at the outlets using lumped parameter models and physiologic flow waveforms were used at the inlets with equal share for native cardiac output and ECMO flow out of 5 LPM total cardiac flow. A particle-tracing model enabled oxygenated blood perfusion analysis in coronary arteries to quantify the impact of ECMO on myocardial perfusion. The model was run within COMSOL for six heart cycles to ensure independency from initial condition. Results: Simulations demonstrate that oxygenated blood provided by upper body venoarterial ECMO perfuses the descending aorta and left subclavian artery where the catheterization occurred rendering the perfusion catheterposition-dependent (Table 1 and Figure 1) but does not provide physiologically significant coronary perfusion. Conclusions: Computational models are indispensable tools for providing insight into complex hemodynamics and hybrid circulations generated by extracorporeal circulatory support. Simulations of the upper body venoarterial ECMO cannulation strategy demonstrates that it provides circulatory support but fails to deliver oxygenated blood to the coronary arteries and risks myocardial ischemia. Figure 1. Particle distribution in peak systole rendering the ECMO-provided, oxygenated blood in red.