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Case studies: Simultaneous intermittent intraatrial and intraventricular conduction defects mimicking trifascicular

J A Reiffel, E M Antman, A J Casella

    Journal of Electrocardiology
    |January 1, 1977
    PubMed

    Insights

    Intermittent intraatrial block with left bundle branch block, causing PR prolongation, can mimic trifascicular delay. Electrophysiology helps distinguish this pseudofascicular defect from true conduction issues.

    Area of Science:

    • Cardiology
    • Electrophysiology
    • Cardiac Conduction System

    Background:

    • Intermittent rate-related left bundle branch block and trifascicular conduction delay are known entities.
    • Intraatrial block combined with left bundle branch block has not been previously documented.

    Observation:

    • A case is presented exhibiting intermittent rate-related intraatrial block and left bundle branch block.
    • This combination resulted in PR prolongation secondary to the intraatrial block.

    Findings:

    • The observed intraatrial block with left bundle branch block mimicked intermittent trifascicular conduction delay.
    • Electrophysiological testing was crucial in differentiating this pseudotrifascicular defect from genuine trifascicular conduction delay.

    Implications:

    • This finding expands the understanding of complex intra-atrial and bundle branch conduction abnormalities.
    • Accurate electrophysiological assessment is vital for diagnosing and managing these pseudotrifascicular defects.
    • Highlights the importance of recognizing atypical presentations of conduction system disease.

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