Nonparoxysmal Junctional Tachycardia

KEY FEATURES

ESSENTIALS OF DIAGNOSIS

• Heart rate 60–120 bpm

• Atrioventricular (AV) dissociation

• Gradual onset and termination

• When rhythm is caused by digoxin, AV dissociation is common

• Usually seen with organic heart disease

GENERAL CONSIDERATIONS

• Causes include:

  • – Digoxin toxicity

  • – Inferior myocardial infarction

  • – Open-heart surgery

  • – Myocarditis

  • – Rarely congenital heart disease

• This arrhythmia is not episodic

• P waves may be before or after or buried in the QRS complex

• Antegrade AV block and intermittent atrial capture may give the appearance of irregular rhythm

• Enhanced vagal tone may slow the arrhythmia but not terminate it

• Digoxin toxicity is the cause of 60% of cases

• Regular ventricular rhythm in atrial fibrillation treated with digoxin should raise suspicion of this arrhythmia

• Twenty percent of cases are secondary to inferior infarction and usually disappear within days

• Valve surgery and myocarditis are other causes of this arrhythmia

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

• Depends on precipitating cause

• Symptoms of digoxin toxicity may be present

• Myocardial infarction or valve surgery history will be self-evident

PHYSICAL EXAM FINDINGS

• Cannon a waves if there is AV dissociation

• Variable S₁ may be present

• Other features depend on underlying cause

DIFFERENTIAL DIAGNOSIS

• Atrial tachycardia

• Atrioventricular nodal reentry tachycardia (AVNRT) (slower heart rate, gradual onset and termination, and lack of termination with vagal maneuvers differentiate the rhythm from AVNRT)

DIAGNOSTIC EVALUATION

LABORATORY TESTS

• CBC, basic metabolic panel

ELECTROCARDIOGRAPHY

• ECG to detect and document the rhythm

• Continuous telemetry until the rhythm resolves

IMAGING STUDIES

• Echocardiogram to evaluate left ventricular function

DIAGNOSTIC PROCEDURES

• Overdrive pacing transiently suppresses the rhythm

TREATMENT

CARDIOLOGY REFERRAL

• All patients should be evaluated by a cardiologist

HOSPITALIZATION CRITERIA

• Most patients are hospitalized at the time of the arrhythmia

• If patients present to the emergency room, they require hospitalization until the rhythm resolves

MEDICATIONS

• No treatment is usually indicated

• Rhythm spontaneously resolves as the inciting event subsides

• If the rhythm is hemodynamically disturbing, AV sequential pacing at a rate faster than the tachycardia may suppress the rhythm and restore the atrial contribution to cardiac output

THERAPEUTIC PROCEDURES

• None required

MONITORING

• No need for monitoring after the rhythm resolves

ONGOING MANAGEMENT

HOSPITAL DISCHARGE CRITERIA

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