Junctional Ectopic Tachycardia

Junctional ectopic tachycardia (JET) is a rare but clinically significant arrhythmia typically occurring in infants and children. This arrhythmia originates in the atrioventricular (AV) node or AV junction, including the bundle of His (BH), and is classified into 2 distinct forms: congenital junctional ectopic tachycardia (CJET) and postoperative junctional ectopic tachycardia (POJET). JET is characterized by abnormal automaticity rather than reentrant mechanisms, a distinction that has important implications for diagnosis and treatment. CJET may present without prior cardiac surgery and can be evident even at birth. This type is associated with substantial morbidity and mortality—reaching as high as 35% in untreated or refractory cases—owing to its often aggressive course and resistance to standard medical therapies. POJET, in contrast, typically develops within the first 72 hours following surgical repair of congenital heart defects. POJET has been attributed to ischemia, mechanical stretching, and direct trauma to the AV conduction system during surgical intervention. Unlike AV nodal reentrant tachycardia (AVNRT) or AV reentrant tachycardia (AVRT), POJET is not driven by a reentry circuit. Clinically, it may present with either a regular or irregular rhythm, with findings such as 1:1 retrograde atrial conduction or AV dissociation with variable ventricular responses. JET often leads to significant hemodynamic compromise due to its rapid ventricular rates, loss of AV synchrony, and resulting reduction in cardiac output. If not promptly recognized and appropriately managed, JET can rapidly progress to low cardiac output syndrome or cardiovascular collapse. Treatment remains challenging, often requiring a combination of supportive measures, antiarrhythmic medications, and sometimes advanced interventions such as temporary pacing or extracorporeal support. Given its complex pathophysiology, variable clinical presentations, and the evolving landscape of therapeutic options, this review aims to provide a comprehensive overview of junctional ectopic tachycardia. This activity discusses its epidemiology, pathophysiology, clinical features, diagnostic approach, and management strategies, with particular attention to both congenital and postoperative forms, and highlights recent advances that may improve outcomes in this vulnerable population.