Myocardial Perfusion and Scarring in Congenital Heart Disease

Background: \- People with congenital heart disease may develop heart failure earlier that those who do not have the disease. One theory to explain this is that the heart s own blood supply may be different in people with congenital heart disease. Problems with this blood supply can severely damage the heart. This damage can be studied with a heart imaging test called a cardiac magnetic resonance imaging (MRI) scan. Researchers want to use this type of scan to look at the blood supply to the heart in people with congenital heart disease. Objectives: \- To learn more about the blood supply to the heart in people with congenital heart disease. Eligibility: \- Individuals at least 18 years of age who have heart defects caused by congenital heart disease. Design: * Participants will be screened with a physical exam and medical history. Blood and urine samples will be collected. * Participants will have a cardiac MRI scan to look at the blood flow to the heart. * Participants will also have a heart stress test to measure heart function during exercise. * Other imaging studies of the heart may be performed to collect more information on heart function.