1. From the Departments of Cardiology (M.H.C., S.D.C.) and Medicine (L.D.), Children's Hospital Boston; Department of Medicine (M.H.C.), Divisions of Women's Health and Cardiovascular Medicine, Brigham and Women's Hospital; Departments of Medical Oncology (M.H.C.) and Pediatric Oncology (L.D.), Dana-Farber Cancer Institute; and the Departments of Medicine (M.H.C.) and Pediatrics (S.D.C., L.D.), Harvard Medical School, Boston, MA.