Paradoxic phenomenon of premature beats with narrow QRS in the presence of bundle-branch block

In contrast to the functional bundle-branch block (BBB) which is frequently rate-related and disappears when heart rate slows, we have encountered seven cases of a paradoxic disappearance of an existing, ischemia-induced BBB in premature beats. Supernormal conduction within the blocked bundle branch...

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Bibliographic Details
Published in:Circulation (New York, N.Y.) N.Y.), 1973-03, Vol.47 (3), p.543-553
Main Authors: Massumi, R A, Hilliard, G, DeMaria, A, Fabregas, R, Lindsay, A E, Amsterdam, E, Mason, D T
Format: Article
Language:English
Subjects:
Adult
Aged
Angina Pectoris - complications
Angina Pectoris - physiopathology
Bundle-Branch Block - complications
Bundle-Branch Block - etiology
Bundle-Branch Block - physiopathology
Coronary Disease - complications
Coronary Disease - physiopathology
Electrocardiography
Female
Heart Conduction System - physiopathology
Heart Rate
Heart Ventricles - physiopathology
Humans
Male
Middle Aged
Myocardial Infarction - complications
Myocardial Infarction - physiopathology
Tachycardia - etiology
Tachycardia - physiopathology
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Summary:In contrast to the functional bundle-branch block (BBB) which is frequently rate-related and disappears when heart rate slows, we have encountered seven cases of a paradoxic disappearance of an existing, ischemia-induced BBB in premature beats. Supernormal conduction within the blocked bundle branch was not present in any of the cases. His bundle electrography in three of the cases demonstrated His spikes before each of the narrow-QRS premature beats. The His-Q intervals of the premature beats were considerably shorter than those of the control sinus beats. This finding clearly indicated an ectopic origin midway between the ventricular myocardium and the His bundle, i.e., within the ischemic fascicles of the left bundle, or the ischemic right bundle. From their points of origin such fascicular impulses propagate antegradely toward the respective area of the ventricular myocardium, and retrogradely toward the main His bundle, and at the same time down the remaining two fascicles. The antegrade conduction time in the short pathway down the ischemic fascicle is equaled by the faster conduction through the longer pathways of the remaining, uninjured fascicles, thereby accounting for the almost simultaneous activation of the myocardium of the two ventricles and the resultant narrow-QRS complexes.
ISSN:0009-7322
1524-4539
DOI:10.1161/01.CIR.47.3.543