A Computational Fluid Dynamics Study of the Extracorporeal Membrane Oxygenation-Failing Heart Circulation

Abstract

Extracorporeal membrane oxygenation (ECMO) is increasingly deployed to provide percutaneous mechanical circulatory support despite incomplete understanding of its complex interactions with the failing heart and its effects on hemodynamics and perfusion. Using an idealized geometry of the aorta and its major branches and a peripherally inserted return cannula terminating in the iliac artery, computational fluid dynamic simulations were performed to (1) quantify perfusion as function of relative ECMO flow and (2) describe the watershed region produced by the collision of antegrade flow from the heart and retrograde ECMO flow. To simulate varying degrees of cardiac failure, ECMO flow as a fraction of systemic perfusion was evaluated at 100%, 90%, 75%, and 50% of total flow with the remainder supplied by the heart calculated from a patient-derived flow waveform. Dynamic boundary conditions were generated with a three-element lumped parameter model to accurately simulate distal perfusion. In profound failure (ECMO providing 90% or more of flow), the watershed region was positioned in the aortic arch with minimal pulsatility observed in the flow to the visceral organs. Modest increases in cardiac flow advanced the watershed region into the thoracic aorta with arch perfusion entirely supplied by the heart.

Cerebral Blood Flow Hemispheric Asymmetry in Comatose Adults Receiving Extracorporeal Membrane Oxygenation

“…Native and ECMO blood typically have different pH levels, oxygen saturations, and amounts of dissolved carbon dioxide. If the mixing cloud lies in between the brachiocephalic trunk and left common carotid artery, the two sides of the brain may receive blood under different pressures and with different levels of oxygen, CO 2 , pulsatility, and pressure ( Stevens et al, 2017 ; Nezami et al, 2021 ). We did not find significant differences in comatose vs. non-comatose patients in average pH, pCO 2 from multiple sources, ECMO flows, MAP range, or pulsatility ( Supplementary Table 1 ).…”

“…This is contrasted with veno-venous (VV) ECMO, in which oxygenated blood is returned to the body via the venous system and perfuses the arterial system in a normal physiologic manner. This distinction is important as asymmetric cerebral and somatic oxygenation and perfusion have been described in VA ECMO ( Cove, 2015 ; Acharya et al, 2017 ; Nezami et al, 2021 ). The presence of disrupted cerebrovascular autoregulation in comatose patients with hypoxic brain injury furthers the possibility of asymmetric perfusion arising from the brain’s interaction with the ECMO circuit and the unique changes in circulatory physiology ECMO produces ( Van Den Brule et al, 2018 ).…”

Increased interhemispheric asymmetry of cerebral blood flow in comatose adult patients on extracorporeal membrane oxygenation

“…Native and ECMO blood typically have different pH levels, oxygen saturations, and amounts of dissolved carbon dioxide. If the mixing cloud lies in between the brachiocephalic trunk and left common carotid artery, the two sides of the brain may receive blood with different levels of oxygen, CO2, pulsatility, and pressure 18 . A previous study looking at angiography of the head in VA ECMO patients illustrated this asymmetric blood flow via filling time of injected iodine contrast 17 .…”

“…The copyright holder for this preprint this version posted October 26, 2021. ; https://doi.org/10.1101/2021.10.25.21265432 doi: medRxiv preprint (VV) ECMO, in which oxygenated blood is returned to the body via the venous system and perfuses the arterial system in a normal physiologic manner. This distinction is important as asymmetric cerebral and somatic oxygenation and perfusion have been described in VA ECMO [16][17][18] . The presence of disrupted cerebrovascular autoregulation in comatose patients with hypoxic brain injury furthers the possibility of asymmetric perfusion arising from the brain's interaction with the ECMO circuit and the unique changes in circulatory physiology ECMO produces 19 .…”

Commentary: Incremental steps to solve challenging problems

“…Mock circulation studies and computational analyses that quantitatively describe the complex interactions of ECMO flow coupled with the effects of an Impella or an IABP are other promising approaches to guide research in this rapidly expanding field. 7,8…”