Congenital Junctional ectopic tachycardia (JET) is a rare and usually incessant tachyarrhythmia that presents in the first few months of life. In the past, treatment of congenital JET was difficult, and the condition was associated with a high mortality [1]. However, with the evolution of amiodarone as the first line of pharmacological management, the outlook for infants with this disorder has improved [2]. We report a neonate with congenital JET who had an incessant arrhythmia, and was managed on a combination of amiadarone and propranolol.

A late pre-term (34 weeks 6 days) baby was delivered via emergency cesarean section. A routine antenatal scan had documented a heart rate of 210/minute and fetal ascites. The liquor volume was normal. Clinical examination of the infant showed a pulse rate of 210/min with good peripheral pulses and normal peripheral perfusion. The respiratory system examination, cardiac examination and abdomen were normal. Echocardiogram revealed a structurally normal heart except for a persistent small atrial communication shunting left to right. The ventricular contractility was preserved on subjective assessment.

The electrocardiogram (ECG) showed a narrow complex regular tachycardia with a heart rate of 200/minute (Fig. 1). There was evidence of atrio-ventricular (A-V) disassociation with an atrial rate of 150/minute. A diagnosis of congenital JET was made and the baby was started on propranolol at a dose of 1 mg/kg/dose four times a day. There was no suppression of tachycardia in 48 hours although the baby remained hemodynamically stable. Hence amiodarone was added at a dose of 10 mg/kg/day followed by a maintenance dose of 5 mg/kg/day. After 4 days of treatment, a satisfactory rate control with reduction of the junctional rate to approximately 120/minute was achieved and the child was discharged on the combination of amiodarone and propranolol.

Fig. 1 ECG showing a regular narrow complex tachycardia with a heart rate of 200/minute and evidence of A-V dissociation. The arrows denote p waves which do not have a consistent relationship with the QRS complexes.

Congenital JET is a rare neonatal arrhythmia that was first reported by Coumel, et al. [3]. It is caused by abnormal automaticity of the A-V node. The ECG typically manifests as a narrow-complex tachycardia with evidence of A-V disassociation or 1:1 retrograde V-A condition. JET with onset in the first few weeks of life is more likely to be incessant or sustained (>50% of QRS complexes) with a high risk of congestive cardiac failure [1,2,4]. Most children require a combination of anti-arrhythmic medications, with amiodarone the most commonly used [2]. Complete or partial control of arrhythmia is possible in only about one-third of cases.

1. Villain E, Vetter V, García JM, Herre J, Cifarelli A, Garson A. Evolving concepts in the management of congenital junctional ectopic tachycardia. A multicenter study. Circulation. 1990;81:1544-9.

2. Collins KK, Van Hare GF, Kertesz NJ, Law IH, Bar-Cohen Y, Dubin AM, et al. Pediatric nonpost-operative junctional ectopic tachycardia: medical management and interventional therapies. J Amer Coll Cardiol. 2009;53:690-7.

3. Coumel P, Fidelle JE, Attuel P, Brechenmacher C, Batisse A, Bretagne J, et al. [Congenital bundle-of-his focal tachycardias. Cooperative study of 7 cases]. Arch Mal Coeur Vaiss. 1976;69:899-909.