Continuous vs pulsatile arterial cannula flow for venoarterial extracorporeal membrane oxygenation: A multiscale computational fluid dynamics analysis

BACKGROUND AND OBJECTIVE: Venoarterial extracorporeal membrane oxygenation (VA ECMO) circuits typically utilise a continuous flow (CF) of blood to support patients suffering from refractory cardiorespiratory dysfunction. Pulsatile flow (PF) VA ECMO is an emerging technology being developed to overcome adverse effects associated with non-physiological CF VA ECMO such as worsening of microcirculatory and cardiac function. However, the flow dynamics associated with PF VA ECMO, such as positioning of the watershed region, wall shear stress, and ventricular unloading are still largely unknown. Therefore, to address this gap, our study aimed to utilise computational fluid dynamics (CFD) to compare the arterial cannula flow characteristics generated by CF and PF VA ECMO. METHODS: A multiscale CFD model was created using a patient-specific aortic geometry and employed a closed-loop lumped parameter network as boundary conditions. Mean VA ECMO flow rates of 3, 4, and 5 L/min were simulated for both CF and counter-pulsed PF scenarios. RESULTS: The hemodynamic results demonstrated increased stroke volume, ejection fraction, and coronary flow during PF VA ECMO, and decreased left ventricular volumes, afterload, and pressure-volume areas, when compared to CF VA ECMO. Delivery of oxygen saturated blood from VA ECMO to the upper body decreased slightly during PF VA ECMO during 4 L/min of support. Lastly, wall shear stress on the aortic wall increased substantially during PF VA ECMO, when compared to CF VA ECMO. CONCLUSIONS: The findings from this study suggest varied hemodynamic and flow dynamic outcomes when comparing CF and PF VA ECMO, each with their own benefits and drawbacks.