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

Masood Akhtar; Mohammad Shenasa; Donald H. Schmidt

doi:10.1172/JCI110116

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

Masood Akhtar, Mohammad Shenasa, and Donald H. Schmidt

Published April 1, 1981 - More info

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Abstract

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 (V₁V₁) ranging from 550 to 900 ms (mean, 657.1±139.5), closely coupled V₂ (mean V₁V₂, 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 of the patients in this series was the PSVT initiated with a retrograde block of V₂ in the atrioventricular node with or without concomitant retrograde A₂ activation via the AP. We conclude that within the ranges of cycle lengths tested, a retrograde block of V₂ and/or V₃ in the HPS is the most common mechanism for initiation of PSVT during ventricular premature stimulation in patients with the Wolff-Parkinson-White Syndrome.