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[Left syncopal bundle-branch block during tachycardia. A new, syndrome?]
J P Donzeau1, A Dechandol, M Marrot
1Clinique Pasteur, Toulouse.
Annales De Cardiologie Et D'Angeiologie
|May 1, 1994
Summary
Left bundle branch block during supraventricular tachycardia can cause syncope, even with normal heart function. This finding is crucial for diagnosing unexplained loss of consciousness.
Area of Science:
- Cardiology
- Electrophysiology
- Internal Medicine
Background:
- Supraventricular tachycardia (SVT) can cause syncope.
- The role of left bundle branch block (LBBB) in SVT-induced syncope is not fully understood.
- Hemodynamic compromise during arrhythmias is a significant clinical concern.
Observation:
- Three cases showed syncope associated with rate-dependent LBBB during SVT.
- No syncope occurred when SVT at the same rate had narrow QRS complexes.
- One case demonstrated significant arterial pressure decrease during atrial pacing-induced LBBB.
Findings:
- Sustained, rate-dependent LBBB can induce syncope.
- Hemodynamic impairment from intermittent LBBB occurs even in patients with normal ventricular function.
- Fast SVT with functional LBBB can cause a dramatic drop in arterial pressure and syncope.
Implications:
- Functional LBBB during SVT is a potential cause of syncope.
- Diagnosing syncope may benefit from considering electrophysiological data of SVT and frequency-dependent LBBB.
- Understanding LBBB's hemodynamic impact is vital for managing patients with arrhythmias and syncope.