Junctional bradycardia: Difference between revisions
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===Physical Examination=== | ===Physical Examination=== | ||
====Vitals==== | |||
=====Pulse===== | |||
The pulse is regular at a rate of 40 to 60 beats per minute | |||
====Neck==== | ====Neck==== | ||
*[[Cannon a waves]] may be present if there is delayed atrial contraction against a closed [[tricuspid valve]] | *[[Cannon a waves]] may be present if there is delayed atrial contraction against a closed [[tricuspid valve]] | ||
Revision as of 11:26, 4 September 2012
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Synonyms and keywords: junctional escape; junctional escape rhythm
Overview
Junctional bradycardia is a slow (40 to 60 beats per minute) narrow complex escape rhythm that originates in the atrioventricular node to compensate for slow or impaired conduction of pacemaker activity in the atrium.
Pathophysiology
Normally, the atrioventricular node (AVN) can generate an escape rhythm of 40-60 beats per minute in case the sinoatrial node (SA node) or atrial pacemakers fail (sinus arrest) or slow (sinus bradycardia) or if there is complete heart block. This junctional escape rhythm generates a normal, narrow QRS complex rhythm at a rte below 60 beats per minute (junctional bradycardia) as the electrical impulses once they are generated are conducted with normal velocity down the usual pathways. Retrograde P waves (i.e. upside down) P waves due to retrograde or backward conduction may or may not be present.
Causes
- Acute MI
- Acute rheumatic fever
- Antiarrhythmic agents
- Beta-blockers
- Calcium channel blockers
- Complete heart block
- Conduction system disease
- Digitalis toxicity
- Diphtheria
- Healthy response during sleep in patients with heightened vagal tone
- Heart surgery particularly valve replacement or surgery for congenital heart disease
- Ischemic heart disease
- Lyme disease
- NSTEMI
- Sick sinus syndrome
- Sinus arrest
- Sinus bradycardia
- STEMI particularly inferior MI involving the posterior descending artery causing ischemia of the AV node due to poor perfusion in the AV nodal artery
Diagnosis
Symptoms
Symptoms are more likely if the atrial rate is faster than the junctional rate (if AV dissociation or complete heart block is present) as compared with the scenario whereby the junctional rate is faster than the atrial rate. The following symptoms may be present:
Physical Examination
Vitals
Pulse
The pulse is regular at a rate of 40 to 60 beats per minute
Neck
- Cannon a waves may be present if there is delayed atrial contraction against a closed tricuspid valve