From the Guidelines
Junctional rhythm is a cardiac arrhythmia characterized by a rapid, occasionally irregular, narrow-complex tachycardia with rates typically between 120 bpm to 220 bpm, resulting from enhanced automaticity from an ectopic focus in the AV junction. Junctional tachycardia is a significant arrhythmia that can be misdiagnosed as other supraventricular tachycardias (SVTs) due to the frequent absence of demonstrable P waves in reentrant rhythms 1. The mechanism of junctional tachycardia is associated with automaticity or triggered activity, and it can be caused by various factors, including digoxin toxicity or myocardial infarction.
Key Characteristics of Junctional Tachycardia
- Rapid, occasionally irregular, narrow-complex tachycardia with rates typically between 120 bpm to 220 bpm
- AV dissociation (often isorhythmic) may be seen, excluding the misdiagnosis of AVRT and making AVNRT highly unlikely
- Can be misdiagnosed as other SVTs, such as AF or MAT, due to the absence of demonstrable P waves
Management of Junctional Tachycardia
- Oral beta blockers are reasonable for ongoing management in patients with junctional tachycardia 1
- Oral diltiazem or verapamil may also be used for ongoing management in patients with junctional tachycardia 1
- Flecainide or propafenone may be reasonable for ongoing management in patients without structural heart disease or ischemic heart disease who have junctional tachycardia 1
- Catheter ablation may be reasonable in patients with junctional tachycardia when medical therapy is not effective or contraindicated 1 It is essential to understand junctional rhythm to distinguish between benign physiological variants and potentially life-threatening cardiac conditions requiring intervention. The management of junctional tachycardia depends on the patient's hemodynamic stability, and asymptomatic patients may require only monitoring, while symptomatic patients may need treatment with beta blockers, diltiazem, or verapamil, or catheter ablation in severe cases 1.
From the Research
Definition of Junctional Rhythm
- Junctional rhythm is a type of heart rhythm that originates from the atrioventricular (AV) junction, which includes the AV node and the bundle of His 2.
- It is characterized by a slow heart rate, typically between 40-60 beats per minute, and is often seen in patients with heart failure or other cardiac conditions 3.
Significance of Junctional Rhythm
- Junctional rhythm can be a sign of underlying cardiac disease, such as heart failure or atrial fibrillation, and can have significant clinical implications 3.
- It can also be a complication of certain medical procedures, such as catheter ablation of the AV junction 3.
- Understanding the mechanisms and characteristics of junctional rhythm is important for diagnosing and treating cardiac arrhythmias, including supraventricular tachycardia 4.
- The AV junction plays a central role in electrophysiology, and junctional rhythm can be influenced by autonomic modulation, including responses to isoproterenol and acetylcholine 2.
Characteristics of Junctional Rhythm
- Junctional rhythm can originate from different regions of the AV junction, including the nodal-His region and the proximal His bundle 2.
- It can be modified by autonomic stimulation, with isoproterenol accelerating the rhythm and acetylcholine slowing it down 2.
- The rhythm can also be influenced by the presence of specialized conduction pathways, including the fast and slow pathways 2.