Demonstration of Re-entry within the His-Purkinje System in Man

Abstract

Re-entry within the His-Purkinje system (HPS) was consistently observed in 15/24 consecutive patients in whom retrograde refractory period studies were performed using His bundle electrograms and the ventricular extrastimulus method. Within a narrow range of ventricular coupling intervals (V₁V₂), V₂ retrogradely conducted to the bundle of His (H₂) with significant infra-His bundle conduction delay (V₂H₂ interval). At critical V₂H₂ delays another beat of ventricular origin (V₃) followed V₂ and was associated with H₂V₃ intervals greater than the H-V intervals of sinus beat. It is postulated that V₂ retrogradely blocked within the right bundle branch and activated the bundle of His via the left bundle branch after which antegrade conduction occurred along the right bundle branch producing the V₃ response. In support of re-entry within the HPS are the following: 1) V₃ occurred in a narrow range of V₁V₂ intervals and critical V₂H₂ delays, 2) V₃ did not occur when V₂ retrogradely blocked below the bundle of His, 3) V₃ was independent of retrograde A-V nodal delay, 4) V₃ rarely occurred in patients with pre-existing complete right bundle branch block pattern. These results reasonably exclude local re-entry near the site of stimulation.