A nonprofit organization conducting research and providing information about arrhythmia, sudden cardiac death, heart disease, and syncope.

St. Luke's-Roosevelt Hospital Center, New York. Descriptions of arrhythmia diagnostic procedures and therapy, with testimonials and news for patients and physicians.

North American Society of Pacing and Electrophysiology, an organization of physicians, scientists and allied professionals, dedicated to the study and management of cardiac arrhythmias.