Multimodality Biomarkers for Noninvasive Assessment of the Fontan Patient

This is a single center prospective longitudinal study and will enroll approximately 50 Fontan patients and 20 controls of a similar age, gender, BMI and physical activity level between the ages of 10-40 years. The investigators will enroll from pediatric cardiology and heart failure clinics and inpatient care units at Children's Health Dallas, adult congenital heart disease clinics and inpatient care units at Clements University Hospital and the Clinical Heart Center. This study will evaluate the multimodality biomarkers for assessment of Fontan circulation including heart, liver and lung and change in these markers with exercise training. Participants will receive an MRI of the Fontan circulation. This will include imaging of the heart, lung and liver. A blood draw (approximately 10 ml) for assessment of serum biomarkers and circulating microRNAs of interest will be completed. The participants will also complete exercise testing and will then start a 3-6 month long cardiac rehabilitation program. Frequent phone follow up (conducted by the research staff) and regular download of data from heart rate monitors will ensure adherence. After the 3-6 month study period the participants will return for a follow up and repeat all testing completed at enrollment.