Exercise MRI to Evaluate Cardiorespiratory Fitness in Children With Heart Disease

Participants will undergo a standard cardiac MRI to assess resting ventricular structure and function then complete an exercise cardiac MRI assessment using an MRI-compatible stepping ergometer.

Cardiopulmonary exercise testing will be performed using a cycle ergometer. Consistent with standard guidelines, workload will progressively increase (10W ramp protocol) such that peak oxygen consumption (VO2peak) is achieved within 8-12 minutes. VO2peak, VO2 at anaerobic threshold, peak power output (PPO), ventilation/carbon dioxide production (VE/VCO2) slope, peak heart rate (HR), and HR recovery at 1- and 3-minutes will be recorded. VO2peak will be converted to age-, weight, and sex-specific norms and a %predicted value.