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Bundle branch block in alternate beats during 2:1 atrial flutter
Francesco Luzza1, Maria Pia Calabrò, Scipione Carerj
1Department of Cardiology, University of Messina, Italy.
Journal of Electrocardiology
|January 3, 2006
Summary
This case study explores atrial flutter with alternating narrow and wide QRS complexes. It suggests tachycardia-dependent left bundle branch block and supernormal conduction explain these findings.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Arrhythmias
Background:
- Atrial flutter can present with complex ventricular conduction patterns.
- Bundle branch blocks can vary in their manifestation during arrhythmias.
- Understanding conduction abnormalities is crucial for diagnosing cardiac conditions.
Observation:
- A patient with atrial flutter exhibited alternating narrow and wide QRS complexes during 2:1 atrioventricular (A/V) conduction.
- Wide QRS complexes showed a left bundle branch block (LBBB) morphology.
- Narrow QRS complexes were observed during pauses or with 4:1 A/V conduction.
Findings:
- The left bundle branch block disappeared with longer R-R intervals, indicating it was tachycardia-dependent (Phase 3 block).
- Alternate beat narrowing of QRS complexes was attributed to supernormal left bundle branch conduction.
- Retrograde concealed conduction into the anterogradely blocked bundle branch was also implicated.
Implications:
- This case highlights the dynamic nature of bundle branch blocks in the context of supraventricular tachycardias.
- It provides insight into the mechanisms of alternating QRS durations during atrial flutter.
- Accurate interpretation of such complex ECG findings is essential for appropriate patient management.