Preoperative Hemodynamics and Brain Injury in Transposition of the Great Arteries

Background: Despite improvements in transposition of the great arteries (TGA) outcomes, perinatal brain injury remains common.ObjectivesThe purpose of this study was to document patterns of brain injury and to explore hemodynamic mechanisms of brain injury in a subset of patients using cardiovascular magnetic resonance (CMR).MethodsPreoperative brain magnetic resonance imaging and CMR were performed between 2014 and 2023. Brain injury was classified as stroke, white matter injury, or hypoxic ischemic injury. Spearman’s correlation was used to assess relationships between hemodynamic parameters.ResultsNeuroimaging was obtained in 225/302 (74.5%) neonates with TGA, of whom 45/225 (20%) underwent CMR. Brain injury included arterial ischemic stroke (22/225; 9.8%), moderate-to-severe white matter injury (19/225; 8.4%), and hypoxic ischemic injury (6/225; 2.7%). Higher ratio of pulmonary to systemic blood flow (QpQs) was associated with lower superior vena cava flow and cerebral oxygen delivery but not cerebral blood flow. Higher QpQs was also associated with a higher ratio of cerebral blood flow to systemic blood flow. Hypoxic ischemic brain injuries occurred early due to a restrictive atrial septum or later, following pulmonary overcirculation.ConclusionsAlthough no clear association was found with brain injury, this study provides evidence that high QpQs is related to lower superior vena cava flow and cerebral oxygen delivery and may predispose infants with TGA to white matter injury and hypoxic ischemic injury. These findings suggest that to preserve cerebral blood flow, preoperative TGA patients who remain hypoxemic after balloon atrial septostomy may be better served by earlier arterial switch operation rather than attempting to increase patent ductus arteriosus size with prostaglandins. Our findings suggest hypoxic ischemic injury secondary to pulmonary overcirculation is also an important form of injury and may be preventable through judicious use of prostaglandin and timely surgical repair.