Introduction
During orthodromic reciprocating tachycardia (ORT), or atrioventricular
reentrant tachycardia, functional bundle branch block (BBB) can be
present when wavefront encroaches on the refractory period of
His-Purkinje system. Ventriculo-atrial conduction time is shortened when
bundle branch conduction is improved during ORT utilizing ipsilateral
concealed accessory pathway (AP) [1-3]. However,
this may exactly advance wavefront to the refractory period of the
circuit components which results in tachycardia termination. Here we
describe a group of patients sharing the phenomenon of ORTs relying on
aberrant conduction based on various mechanisms.