Junctional Rhythm Clinical Presentation

Updated: Sep 22, 2016
  • Author: Sean C Beinart, MD, FACC, FHRS; Chief Editor: Jeffrey N Rottman, MD  more...
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Presentation

History

Junctional rhythms may be accompanied by symptoms or may be entirely asymptomatic. Note the following:

  • Palpitations, fatigue, or poor exercise tolerance: These may occur during a period of junctional rhythm in patients who are abnormally bradycardic for their level of activity.
  • Dyspnea: Sudden onset of symptoms and sudden termination of symptoms may occur, especially in the setting of complete heart block.
  • Presyncope (near syncope): The underlying cause of the junctional rhythm is the most significant predictor of symptoms. For instance, AV dissociation with complete heart block, defined as an atrial rate that is faster than the junctional escape rate, is more likely to cause symptoms than AV dissociation with a sinus rate slower than the competing junctional pacemaker. Additionally, syncope or presyncope may occur from an acute decrease in heart rate.
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Physical

A predominant junctional rhythm may be associated with structural heart disease, sick sinus syndrome, or both, during which the junctional escape rhythm supersedes the sinus rate and provides a safety mechanism.

During a predominant junctional rhythm, the pulse usually is regular and the heart rate may be within reference range. Frequently, the junctional rhythm is 40-60 beats per minute.

Prominent jugular venous pulsations (ie, cannon a waves) may be present due to the right atrium contracting with a closed tricuspid valve.

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Causes

Causes of junctional rhythm include the following:

  • Sick sinus syndrome (including drug-induced)
  • Digoxin toxicity
  • Ischemia of the AVN, especially with acute inferior infarction involving the posterior descending artery, the origin of the AV nodal artery branch.
  • Acutely after cardiac surgery, especially in children within 4 days after surgery for congenital cardiac defects; a literature review by Cools and Missant indicated that in patients undergoing surgery for congenital heart disease, the risk of junctional ectopic tachycardia is increased by surgery near the AV node, cardiopulmonary bypass operative time of over 90 minutes, young age, the use of inotropic drugs, and hypomagnesemia [2]
  • Acute inflammatory processes (eg, acute rheumatic fever, lyme disease), which may involve the conduction system
  • Diphtheria
  • Other drugs (eg, beta-blockers, calcium blockers, most antiarrhythmic agents) that cause sinus bradycardia
  • Metabolic states with increased adrenergic tone
  • Isoproterenol infusion
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