The Human Atrioventricular Node: Oedipus and the Riddle of the Sphinx.

Cardiac pathologists and electrophysiologists have studied the atrioventricular (AV) node for more than 100 years, since 1906, when Tawara first described the inferior extensions of the AV node in the human heart. Still, this important cardiac structure remains “a riddle wrapped up in a mystery, inside an enigma”, to recall the famous Churchill quotation. Perhaps the same can be said about atrioventricular nodal re-entrant tachycardia (AVNRT): it represents the most common regular tachycardia in humans; since 1973 it has been associated with re-entry within or around the node; and still, its exact circuit remains elusive.