Wolff-Parkinson-White Syndrome

Abstract

Total atrioventricular bypass (Kent bundle) does not explain all the findings in some cases of Wolff-Parkinson-White (W-P-W) syndrome. Two cases are reported in which two accessory pathways, set in series or in parallel, could be demonstrated. In case 1, a short P-R interval, gap phenomenon, and presence of delta wave with either a short or long P-R interval suggested the hypothesis of an atrio-His accessory path (James fibers). The presence of a type-B delta wave during His stimulation demonstrated the takeoff of another bypass (Mahaim fibers) below or at the point of stimulation. The His-ventricle accessory path had a supernormal phase of conduction during either atrial or His stimulation. In case 2, the rapid spread of the impulse to the His bundle (P-H 65 msec) was responsible for a normal H-R interval (35 msec) during either reciprocating tachycardia or normal sinus rhythm wtih a nonwidened QRS and minimal W-P-W deformity (partial cancellation of the delta wave). During reciprocating tachycardia, alternatively short and long P'-H intervals with constant H-R (His bundle) and R-P' (Kent bundle) were due to alternate antegrade atrio-His conduction through the atrionodal bypass (James fibers) and the A-V node. Surgical findings confirmed the existence of a left bundle of Kent. The division of the His bundle resulted in a maximal W-P-W deformity (type A) and abolished the reciprocating tachycardia.

Modulation of conduction and refractoriness in atrioventricular junctional reentrant circuit. Effect on reentry initiated by atrial extrastimulus.

“…It has been reported that the mechanism of prevention of reentry with dual chamber pacing is primarily the failure to achieve sufficient conduction delay in the anterograde pathway (9,27,28). While mitigation of conduction delay may play a role, it is not the only factor that prevents reentry.…”

“…Programmed electrical stimulation has proved to be a singularly useful method for study ofreentrant circuits (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). Since the original description of this method by Schmitt and Erlanger (1); the conduction characteristics ofthe premature beat have remained the primary focus of studies concerning reentrant circuits.…”

“…In a previous study, we observed the effect of bidirectional activation ofthe His-Purkinje system on conduction, refractoriness, and occurrence of bundle branch reentry (19,20). Since conduction delay and conduction block also play a pivotal role in atrioventricular junctional reentrant Address reprint requests to Dr. Mahmud, Section of Cardiology, School of Medicine, East Carolina University, Greenville, NC 27858- 4354. Receivedfor publication 18 (AVJRe)' tachycardias (8)(9)(10)(11)(12), we hypothesized that if conduction and refractoriness were affected by changing the activation sequence of the AVJRe circuit during basic drive, then a new set of relationships would emerge between conduction delay, conduction block, and coupling interval of the extrastimulus. These observations could potentially result in a clearer understanding of electrophysiological factors that facilitate or prevent clinical tachycardias.…”

The Myocardium

“…Sites at which antiarrhythmic drugs act may also be studied in this way. Refractory periods of the different cardiac regions can be studied before and after pharmacological interventions by the technique of the single extrastimulus test (Wellens 1971) and where an anomalous accessory pathway exists between the atria and ventricles, as in the Wolff-Parkinson-White and Lown-Ganong-Levine syndromes, information regarding the fastest rates of one-to-one conduction across the accessory pathway and its refractory period are essential in the assessment of its electrophysiological properties in relation to paroxysmal tachyarrhythmias which may complicate such syndromes (Coumel et al 1972).…”

Treatment of Permanent Junctional Reciprocating Tachycardia in a Preterm Neonate: Case Report

“…Permanent junctional reciprocating tachycardia (PJRT), first defined by Coumel et al 1 in 1967, is an in frequent form of re-entrant supraventricular tachycardia (SVT). PJRT is most often observed in infants and children and can cause incessant tachycardia at a rate between 120 and 250 beats/min.…”