Capturing Physiologic Autonomic Data from Clinically Indicated Magnetic Resonance Imaging Scans in Children

The Fontan Procedure is a palliative surgical procedure used in pediatric patients with one functional ventricle. The procedure, a series of stepwise operations that alter cardiorespiratory physiology, separate the systemic and pulmonary circulations to create Fontan physiology, where the systemic venous blood flows passively and without ventricular thrust into the pulmonary circulation. The hallmark of the Fontan circulation is a sustained, abnormally elevated central venous pressure combined with decreased cardiac output, especially during periods of increased demands. Results of several studies in Fontan patients have shown reduced parasympathetic and sympathetic activity compared to controls. In children with congenital heart disease, a differential diagnosis of autonomic dysfunction may be part of their pathophysiology, a compensatory mechanism, a consequence of surgical procedures or a combination of these.

In children, measurement of ANS function is equally important. Children with single ventricle physiology (and other cardiac conditions) have routine surveillance and cardiac magnetic resonance (CMR) imaging to monitor for disease progression. While autonomic data is routinely collected and is available from these scans, these data are rarely, collected and analyzed; however, our group has shown feasibility. Therefore, autonomic data is usually unavailable in children. Despite the availability of agerelated normal values, the predictive power of autonomic activity is understudied in children and there are no published studies of quantification of autonomic data in this population.