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Atrioventricular dissociation exacerbating posturally-induced syncope.
N Samniah1, S Sakaguchi, D G Benditt
1Division of Cardiology, University of Minnesota, Minneapolis MN 55455, USA.
Summary
An 85-year-old experienced syncope due to an accelerated junctional rhythm causing atrio-ventricular (AV) dissociation. This AV dissociation, not heart rate, was key to developing hypotension and syncope.
Area of Science:
- Cardiology
- Electrophysiology
- Autonomic Nervous System
Background:
- Neurally-mediated syncope is common, often linked to autonomic dysfunction.
- Understanding the mechanisms of syncope, particularly hypotension, is crucial for diagnosis and management.
Observation:
- An 85-year-old patient presented with posturally-induced syncope.
- Tilt table testing reproduced syncope, revealing an accelerated junctional rhythm with atrio-ventricular (AV) dissociation.
Findings:
- Electrophysiologic testing confirmed that AV dissociation, not just heart rate, caused symptomatic hypotension.
- An accelerated junctional rhythm led to hypotension, while a faster atypical AV nodal re-entrant tachycardia (AVNRT) did not, highlighting the role of AV synchrony.
Implications:
- Symptomatic hypotension due to AV dissociation may be a distinct manifestation of neurally-mediated syncope.
- This case underscores the importance of assessing AV synchrony in patients with unexplained syncope and autonomic disturbances.