Interpolated junctional extrasystoles mimicking complex polymorphic ventricular arrhythmias in a healthy young athlete: a case report.

Strange and rare electrocardiogram pictures may be observed during sport pre-participation screening. The small atrioventricular (AV) junction is made up of many specialized fibres with different conduction properties. Junctional arrhythmias can have a normal anterograde conduction or can be conducted with aberrancy. Rarely, they can be interpolated and cause PR prolongation or bundle branch block by increasing the refractory period of the AV node and/or the conduction system. When aberrancy occurs, they can be mistaken for 'atypical' ventricular arrhythmias. Prognosis of these events remains uncertain.