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Left ventricular end-diastolic extrasystole with pseudonormalization of a left bundle branch block unmasking inferior
M A Arnau Vives1, L A Bonet, L A Lalaguna
1Cardiology Department, La Fe Hospital, Valencia, Spain.
Insights
This study shows how occasional normalization of heartbeats in left bundle branch block can reveal underlying ischemia. Ventricular fusions with extrasystoles are key to diagnosing inferior subepicardial ischemia.
Area of Science:
- Cardiology
- Electrophysiology
- Diagnostic Imaging
Background:
- Left bundle branch block (LBBB) complicates electrocardiogram (ECG) interpretation.
- Intraventricular conduction abnormalities can mask or mimic other cardiac conditions.
Observation:
- An ECG tracing demonstrated conducted sinus rhythm with LBBB and intermittent pseudonormalization of QRS complexes.
- This pseudonormalization was linked to ventricular fusion beats originating from the left His-Purkinje system.
Findings:
- Ventricular fusion beats, specifically end-diastolic extrasystoles distal to the LBBB block site, were identified as the cause of transient conduction normalization.
- This normalization of ventricular activation facilitated the diagnosis of inferior subepicardial ischemia.
Implications:
- Recognizing pseudonormalization in LBBB is crucial for accurate ischemia detection.
- Understanding ventricular fusion mechanisms aids in diagnosing subtle myocardial abnormalities.
- ECG analysis of LBBB can be enhanced by considering extrasystolic events.
Abstract:
An electrocardiogram tracing of a patient in conducted sinus rhythm with left bundle branch block is shown, in which occasional pseudonormalization of intraventricular conduction is seen. This event is attributed to ventricular fusions with end-diastolic extrasystoles of the left His-Purkinje system distal to the block site. This type of extrasystole is discussed. In this case, normalization of ventricular activation allowed for diagnosis of inferior subepicardial ischemia.