Junctional bradycardia electrocardiogram

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mugilan Poongkunran M.B.B.S [2]

Junctional bradycardia or AV junction rhythm is usually caused by the absence of the electrical impulse from the SA node. This usually appears on an EKG with a normal QRS complex accompanied with an inverted P wave either before, during, or after the QRS complex.

A 12 lead EKG should be obtained to evaluate the rhythm. In so far as it may alter treatment, any co-existing rhythm disturbance that may have precipitated junctional bradycardia should be ascertained such as:

• AV dissociation
• Complete heart block
• Digitalis toxicity
• Sinus arrest
• Sinus bradycardia
• ST elevation MI

The characteristic EKG findings in junctional bradycardia patients are:

• The rate is 40-60 beats per minute.
• The rate is generally regular.
• The QRS complex is narrow.
• Retrograde P waves may be present due to retrograde conduction from the AV node. The P waves will be inverted in leads II and III.
• The P wave may be buried within the QRS complex and may not be discernable.
• A slow AV nodal reentry tachycardia (AVNRT) should be excluded.

A cardiac event monitor may be helpful in patients with transient symptoms or palpitations to exclude other rhythms such as ventricular tachycardia.

• There is normal conduction in the His bundle, and the His-ventricular interval is normal.
• Preceding each QRS, there should be a His bundle depolarization
• AV conduction is variable
• VA conduction is variable

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