Wolff-Parkinson-White syndrome type B with tachycardia-dependent (phase 3) block in the accessory pathway and in left bundle-branch coexisting with rate-unrelated right bundle-branch block

I. Mendoza, A. Castellanos, R. J. Sung

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5 Scopus citations


A patient with Wolff-Parkinson-White syndrome type B developed 2:1 atrioventricular block resulting from the association of persistent right bundle-branch block with tachycardia-dependent (phase 3) left bundle-branch block. Electrophysiological studies disclosed the coexistence of a tachycardia-dependent (phase 3) block in the accessory pathway. This conduction disturbance was exposed, not by carotid sinus massage as in previous studies, but by pacing-induced prolongation of the interval between two consecutively conducted atrial impulses. Furthermore, the surface electrocardiogram showed, at different times, ventricular complexes resulting from: (1) exclusive atrioventricular conduction through the normal pathway without bundle-branch block; (2) predominant, or exclusive, atrioventricular conduction through a right-sided accessory pathway; (3) exclusive atrioventricular conduction through the normal pathway with right bundle-branch block; (4) exclusive conduction through the normal pathway, with left bundle branch-block; (5) fusion between (1) and (2); and finally, (6) fusion between (2) and (3). However, QRS complexes resulting from simultaneously occurring Wolf-Parkinson-White syndrome type B and left bundle-branch block could not be identified. Future electrophysiological investigations should re-evaluate the criteria used to differentiate true and false patterns of Wolff-Parkinson-White syndrome type B coexisting with left bundle-branch block.

Original languageEnglish (US)
Pages (from-to)481-486
Number of pages6
JournalBritish heart journal
Issue number4
StatePublished - Jan 1 1980


ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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