Introduction
Nodo-ventricular (NV) fiber is a rare type of Mahaim’s bundle which connects the atrio-ventricular (AV) node and the ventricular myocardium. In the light of low prevalence of Mahaim’s bundle (<3%)[1], occurrence of NV fibers is even rare. Previous literatures about NV fibers were mainly case reports and not all of them were describe clearly. We met with 3 cases of NV fibers from 3 hospitals in the recent 3 years. We will clarify the electrophysiological mechanisms of these NV fibers by analyzing their similarities and individual characteristics.