Role of Retrograde His Purkinje Block in the Initiation of Supraventricular Tachycardia by Ventricular Premature Stimulation in the Wolff-Parkinson-White Syndrome

Abstract

A B S T R A C T The precise mechanisms for paroxysmal reentrant supraventricular tachycardia (PSVT) initiation during right ventricular premature stimulation (V2 method) were analyzed in 14 consecutive patients with Wolff-Parkinson-White Syndrome in whom the PSVT was inducible during retrograde refractory period studies. 9 patients had left-sided and the remaining 5 of 14 had right-sided ventriculo-atrial (VA) accessory pathway (AP). At the basic cycle lengths (V,V1) ranging from 550 to 900 ms (mean, 657.1+139.5), closely coupled V2 (mean V,V2, 357.3+59.2 ms, range 320-500) produced retrograde His bundle (H2) activation via the bundle branches and retrograde atrial (A2) activation via the AP. As the V1V2 were further shortened, the V2 showed a retrograde block in the His Purkinje system (HPS) and conducted to the atria via AP in 9 of 14 cases. Subsequently, the A2 impulse conducted anterograde over the atrioventricular node-HPS to initiate a PSVT or an atrial echo response in all nine cases. In none of the patients was a PSVT induced by V2 when the latter produced retrograde H2 activation via the bundle branches. In 10 of 14 cases, however, the retrograde H2 was followed by a V3, due to macroreentry in the HPS. The V3 in turn blocked retrogradely in the HPS while producing A3 via the AP to initiate a PSVT or an atrial echo response in 9 of 10 cases. Retrograde block of V2 and/or V3 in the HPS resulted in PSVT initiation in 13 of 14 cases, whereas in the remaining 1 case the exact mechanism was not clear. In none ofthe patients in this series was the PSVT initiated with a retrograde block of

Electrophysiologic mechanisms of functional bundle branch block at onset of induced orthodromic tachycardia in the Wolff-Parkinson-White syndrome. Role of stimulation method.

“…This finding will require confirmation Fig. 4) follows from postgap shortening of the V2H interval (4) in B (to 210 ms) and from the alteration in the His-RB relationship (11,13) When fx BBB did occur during propagation of A2, we observed that the same type of aberrant conduction was sustained through the next beat (first OT complex), presumably through a linking-by-interference mechanism (18) involving transseptal retrograde invasion from the contralateral bundle (19). Because the A2 method typically induces fx RBBB more commonly than fx LBBB (17), it is not surprising that such was also the case in our series during conduction of A2 and, hence, at OT onset.…”

“…pacing as well as A2 and V2 methods (at one or more basic cycle lengths) Incomplete RBBB was defined by the appearance of terminal rightto assess anterograde and retrograde conduction and refractory periods, ward conduction delay with QRS prolongation to a value < 120 ms. and to induce OT as previously described (6). Accessory pathway localWhen OT was induced by the V2 method, differentiation of anteroization was accomplished using standard criteria (7), including quantigrade from retrograde origin of the (emergent) His deflection following tation of the change in ventriculoatrial (VA) interval (measured on the V2 was accomplished using previously published criteria (4). It was posHis bundle electrogram) accompanying the occurrence of sustained sible, therefore, to distinguish also between fx complete LBBB (at OT (>three beats of) fx BBB during OT (2).…”

Linking: a dynamic electrophysiologic phenomenon in macroreentry circuits.

“…This dynamic process is initiated by retrograde block in the His-Purkinje system during the third paced ventricular beat, 14 15 with subsequent anterograde activation of the atrioventricular node and His bundle from the impulse propagating retrogradely to the atria via the accessory pathway (as depicted schematically in figure 6, A and B). The anterogradely traveling wavefront fails to produce a ventricular echo, however, due to block below the His caused by residual His-Purkinje system refractoriness engendered by the third paced ventricular beat (figure 6, C).…”

“V‐H‐A Pattern” as a Criterion for the Differential Diagnosis of Atypical AV Nodal Reentrant Tachycardia from AV Reciprocating Tachycardia

“…In AVRT utilizing a posterior paraseptal accessory pathway, retrograde VA conduction occurs via the accessory pathway and, even if intraventricular conduction delay is induced in the His‐Purkinje system by the extrastimuli, the atrial tissue near the AV node is activated by the wavefront spreading from the accessory pathway in most patients 19,20 . In this case, the VA interval remains unchanged, or is slightly prolonged when the extrastimuli are close to the refractory period of the accessory pathway, 20 and therefore, His deflection may be superimposed by the atrial potential.…”