Atrioventricular Dissociation Clinical Presentation
- Author: Chirag M Sandesara, MD; Chief Editor: Jeffrey N Rottman, MD more...
AV dissociation can be asymptomatic, but if symptoms related to AV dissociation are present, they are related to bradycardia, tachycardia, AV dyssynchrony, or loss of atrial "kick" and include the following:
- Exertional dyspnea
- Throbbing sensation in neck
- Fatigue, malaise
Physical findings are related to bradycardia, tachycardia, AV dyssynchrony, and lack of an atrial kick at least intermittently. They include the following:
- General appearance - Variable pulse or blood pressure due to the changing relationship between atrial and ventricular contractions
- Pulse - Pulse volume is variable, with fast or slow rates depending on the underlying cause
- Blood pressure - Low in ventricular tachycardia
- Jugular venous pulse - Intermittent cannon a waves are noted when atria and ventricles contract simultaneously; a waves vary as PR interval varies or if the P wave is immediately followed by a QRS
- Heart sounds: Variable intensity of first heart sound; cyclic increase in intensity of first heart sound as PR interval shortens, climaxed by a very loud sound (bruit de cannon); occurs when ventricular rate exceeds atrial rate and QRS occurs just after P wave
- Beat-to-beat variation in systolic murmurs
Major causes of AV dissociation include ventricular tachycardia, nonparoxysmal junctional tachycardia, escape junctional rhythm, and accelerated idioventricular rhythm.
In nonparoxysmal junctional tachycardia, junctional rhythm/tachycardia occur at a rate faster than the sinus rate, without retrograde atrial capture. This is observed in clinical situations such as digoxin toxicity; sinus bradycardia with escape junctional rhythm; and after cardiac surgery, particularly valve surgery or replacement.
Long postectopic cycles allow escape junctional rhythm.
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