Patients with pulmonary regurgitation after surgical correction of ToF over 13 years old will be recruited from the UCSF adult congenital heart disease clinic. Since there is no data in the literature describing the prevalence of abnormal MRI volumetric and functional parameters in asymptomatic patients with PR after ToF repair, a pilot study with 30 patients will be conducted. Increase in sample size may be necessary in the future to accurately interpret the data. After informed consent is obtained, clinical history and physical examination as well as review of old charts will be performed to characterize these patient's clinical status. All patients will undertake a graduated supine bicycle exercise test with MVO2 measurement to assess exercise capacity.
MRI studies will be performed in a 1.5 tesla unit. SSFP cine images will be obtained in the short-axis plane encompassing the entire heart. Velocity-encoded cine MR images will be obtained perpendicular to the direction of blood flow in the main pulmonary artery. Volumetric and flow analysis will be performed in a separate dedicated workstation by a radiologist. End-diastolic volume, end-systolic volume, ejection fraction, total ejection fraction and pulmonary regurgitant fraction will be calculated.