Transient disappearance of left bundle branch block pattern: an unusual ECG presentation of acute pulmonary embolism

Abstract

A 61 year old man developed acute pulmonary embolism while in hospital. His previous and admission electrocardiograms (ECGs) showed a typical left bundle branch block (LBBB) pattern. Immediately after the onset of acute pulmonary embolism, LBBB disappeared from his body surface ECG with sinus bradycardia, normalisation of QRS duration, prolonged QT interval, and marked T abnormalities to the right precordial leads. Recovery from pulmonary embolism resulted in reappearance of his left bundle branch pattern. Delayed conduction of the previously unaffected right bundle branch resulting in roughly equivalent onset of ventricular activation is the most likely reason. Rate dependent LBBB is also discussed.

Episodic Left Bundle Branch Block—A Comprehensive Review of the Literature

“…However, transient LBBB caused by sinus tachycardia can rarely be the prominent conduction abnormality in this condition. On the other hand, transient LBBB disappearance in acute pulmonary embolism has been described . A possible mechanism for this apparently bizzare phenomenon is the conduction delay along the right bundle branch which may result from acute pulmonary vascular obstruction and right ventricular strain.…”

“…A possible mechanism for this apparently bizzare phenomenon is the conduction delay along the right bundle branch which may result from acute pulmonary vascular obstruction and right ventricular strain. However, the appearance of a slower heart rate after pulmonary embolism is another possible explanation either because slower rates can slow conduction along the right bundle or because the previous “normal” heart rate is higher than the critical rate leading with that way to a rate‐dependent LBBB which disappears in slower heart rates …”

Bloqueo de rama intermitente revision de tema y abordaje de una entidad clinica compleja

“…Por otro lado, la desaparición transitoria del BRIHH en la embolia pulmonar aguda ha sido descrito (Athar et al, 2002). Un posible mecanismo para este fenómeno aparentemente extraño es el retraso en la conducción a lo largo de la rama derecha del haz que puede resultar de la obstrucción vascular pulmonar aguda y la tensión del ventrículo derecho.…”