Atrioventricular Dissociation Clinical Presentation
- Author: Chirag M Sandesara, MD; Chief Editor: Jeffrey N Rottman, MD more...
History
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
- Light-headedness
- Throbbing sensation in neck
- Palpitations
- Fatigue, malaise
Physical
Physical findings are related to bradycardia, tachycardia, AV dyssynchrony, and lack of an atrial kick at least intermittently.
- 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
Causes
Major causes of AV dissociation include ventricular tachycardia, nonparoxysmal junctional tachycardia, escape junctional rhythm, and accelerated idioventricular rhythm.
- Ventricular tachycardia[3]
- 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 cycle allowing escape junctional rhythm
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