Permanent junctional reciprocating tachycardia

AVRT

Permanent Junctional Reciprocating Tachycardia (PJRT) is a rare type of supraventricular tachycardia (SVT) characterized by a reentrant or reciprocating mechanism involving the atrioventricular node (AV node) and an accessory pathway. Unlike other forms of SVT, PJRT tends to be incessant and can lead to tachycardia-induced cardiomyopathy if not properly managed. This condition is more commonly diagnosed in children and young adults, but it can affect individuals of any age.

Etiology and Pathophysiology

PJRT is caused by the presence of an accessory pathway, known as a concealed accessory pathway, which connects the atria and ventricles in addition to the normal AV conduction system. This pathway has unique electrophysiological properties, including slow conduction and the ability to conduct in a retrograde direction from the ventricles to the atria. The slow conduction through the accessory pathway allows it to recover in time to participate in the next cardiac cycle, creating a reentrant circuit that perpetuates the tachycardia.

Clinical Presentation

Patients with PJRT may present with palpitations, fatigue, dizziness, or even syncope due to the sustained high heart rates. In infants and young children, symptoms may be less specific and include irritability, feeding difficulties, or failure to thrive. Over time, the persistent tachycardia can lead to tachycardia-induced cardiomyopathy, characterized by dilated cardiomyopathy and heart failure if left untreated.

Diagnosis

The diagnosis of PJRT is primarily based on electrocardiogram (ECG) findings. The hallmark of PJRT on ECG is a long RP interval with a short PR interval during tachycardia, indicating retrograde P waves. These findings differentiate PJRT from other forms of SVT. Advanced diagnostic techniques, such as electrophysiological study (EPS), can further confirm the diagnosis by mapping the accessory pathway and elucidating the mechanism of the tachycardia.

Treatment

The management of PJRT includes both acute and long-term strategies. Acute episodes of tachycardia may be terminated using vagal maneuvers or intravenous administration of antiarrhythmic drugs such as adenosine. Long-term management may involve the use of oral antiarrhythmic medications to prevent recurrence of tachycardia. However, the definitive treatment for PJRT is catheter ablation, which targets and ablates the accessory pathway, thereby interrupting the reentrant circuit responsible for the tachycardia. Catheter ablation has a high success rate and is considered the treatment of choice, especially in patients who are symptomatic or have evidence of tachycardia-induced cardiomyopathy.

Prognosis

With appropriate treatment, the prognosis for patients with PJRT is generally excellent. Catheter ablation offers a curative approach, and most individuals can expect to lead normal lives post-procedure. However, it is crucial to diagnose and treat PJRT early to prevent the development of tachycardia-induced cardiomyopathy and its associated complications.