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Tachycardia- and bradycardia-dependent left bundle branch block associated with first degree a-v block. A study using
Japanese Heart Journal
|November 1, 1976
Summary
This study details a rare case of intermittent left bundle branch block (LBBB) dependent on both fast and slow heart rates, diagnosed using His bundle electrography. The findings highlight the diagnostic value of electrographic recordings in identifying rate-dependent conduction disturbances.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Diagnostics
Background:
- Intermittent left bundle branch block (LBBB) can present complex diagnostic challenges.
- Understanding rate-dependent conduction disturbances is crucial for patient management.
Purpose of the Study:
- To investigate a unique case of tachycardia- and bradycardia-dependent LBBB.
- To evaluate the utility of His bundle electrography and carotid sinus compression in diagnosing rate-dependent intraventricular conduction abnormalities.
Main Methods:
- His bundle electrographic examination was performed.
- Carotid sinus compression and atrial pacing were utilized.
- Analysis of corrected RR intervals and HV intervals was conducted.
Main Results:
- Left bundle branch block (LBBB) occurred at corrected RR intervals below 920 ms and above 1600 ms.
- Normal intraventricular conduction was observed between these intervals.
- The patient demonstrated both tachycardia- and bradycardia-dependent LBBB with first-degree atrioventricular block due to HV block.
Conclusions:
- This represents the first reported case of tachycardia- and bradycardia-dependent bundle branch block studied by His bundle electrography.
- His bundle recordings and carotid sinus compression are vital for diagnosing rate-dependent intraventricular conduction disturbances.
- The study discusses potential mechanisms for this rare condition.