Basics
Description
- Normally, heart beat is initiated by the sinus node (ie, sinus rhythm).
- When it originates from the atrioventricular junction, it is called a junctional rhythm.
- A rhythm that is <100 bpm is usually considered an escape rhythm, as during sinus bradycardia. If it is faster, it is called junctional tachycardia.
Epidemiology
Depends on patient population, and can be seen in all ages.
Risk Factors
None specific
Etiology
- Idiopathic
- Junctional ectopic tachycardia (JET) is a rapid arrhythmia that can be life-threatening, seen in youth after congenital heart disease operations with β-adrenergic stimulation.
- Seen in older individuals in concert with acute MI (especially inferior with enhanced vagal tone) and as a manifestation of drug toxicity
- Catecholamine stimulation
Diagnosis
Signs and symptoms:
- Asymptomatic
- Palpitations
- Dyspnea
- Heart failure (if incessant, causing "tachycardia-associated cardiomyopathy")
Tests
- EKG shows narrow QRS tachycardia without discernible P waves. If there is retrograde conduction to the atria, a P wave can be seen following the QRS.
- For the specific arrhythmia JET, there is often atrioventricular (AV) dissociation because junctional rate is significantly greater than atrial rate.
Lab
Only to assess drug levels if patient is thought to have toxicity
Differential Diagnosis
- AV nodal reentry
- AV reentry
- Permanent form of junctional reciprocating tachycardia, which virtually always has a deeply inverted P wave in ECG leads II, III, and aVF with the RP interval longer than the PR interval; this may result in a tachycardia-induced cardiomyopathy
- Ectopic atrial tachycardia
- Sinus tachycardia
- Atrial flutter
Treatment
Medication
- Drugs not often effective
- Sometimes substrate may be abatable, but risk for damage to normal AV conduction may be significant (AV node or His bundle)
- For postoperative JET, β-blockers, verapamil, procainamide (with hypothermia), and amiodarone have been used with varying success.
- For accelerated idioventricular rhythm in acute MI, administration of antiarrhythmic drugs may suppress this escape pacemaker and lead to asystole:
- In this setting, observation is indicated because the junctional rhythm usually resolves.
- Especially common in inferior MI.
Additional Treatment
General Measures
Remove precipitating cause (toxic drug, catecholamine stimulation).
Surgery
Usually a pacemaker is not needed.
In-Patient Considerations
Admission Criteria
Usually arrhythmia is 1st recognized in inpatients. Discharge is determined by resolution of other medical problems.
Ongoing Care
Follow-Up Recommendations
Patient Monitoring
Usually arrhythmia is transient and corrects during hospitalization for underlying cause.
Patient Education
Depending on presentation and underlying disease:
- If observed in healthy athlete with high vagal tone, no intervention is necessary.
- Rarely, electrophysiologic study may be considered to identify substrate and perhaps cure with ablation (ie, AV nodal reentry, AV reentry, ectopic atrial tachycardia).
Prognosis
Depends on underlying diseases
Additional Reading
1Hamdan MH, Scheinman MM. Role of invasive EP testing in the evaluation and management of junctional tachycardia. Cardiol Electrophysiol Rev. 1997;4:439-442.2Walsh EP, Saul P, Sholler GF. Evaluation of a staged treatment protocol for rapid automatic junctional tachycardia after operation for congenital heart disease. J Am Coll Cardiol. 1997;29:1046-1053. [View Abstract]
Codes
ICD9
427.89 Other specified cardiac dysrhythmias
SNOMED
11849007 atrioventricular junctional rhythm (disorder)