1. Section of Cardiac Electrophysiology (A.E., D.C., F.E.M., F.G.)
2. Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia. Instituto de Cardiologia. Centro Internacional de Arritmias “Andrea Natale,” Fundacion Cardioinfantil, Bogota, Colombia (L.C.S.)
3. Cardiac Eletrophysiology, Cardiology Division, Tel-Aviv Souraski Medical Center, Israel (R.R.).
4. Department of Medicine (F.E.S.)