1. From the Texas Cardiac Arrhythmia Institute at St David’s Medical Center (L.D.B., D.J.B., R.H., A.N.), Austin, Tex; the Department of Cardiology (L.D.B.), University of Foggia, Foggia, Italy; the Cleveland Clinic (L.D.B., C.S.E., C.D.B., R.B., A.S., T.S.F., D.P., L.A., C.T.W., S.K., C.K.C., K.P., R.A.S., J.E.C., M.A., W.I.S., M.D.), Cleveland, Ohio; Stanford University (A.N.), Palo Alto, Calif; and the Fundation Cardio Infantil (L.C.S., M.V.), Bogota, Colombia.