[Familial junctional ectopic tachycardia: clinical and pathological findings].

We describe two brothers with a neonatal diagnosis of junctional ectopic tachycardia. The first brother presented hydrops fetalis secondary to narrow QRS tachycardia at a rate of 230-300 beats/min with atrioventricular dissociation. Although the ventricular rate was controlled with intravenous amiodarone the baby died a few hours after initiation of this treatment from ventricular fibrillation and electromechanical dissociation. Histological examination of the conduction system showed diffuse hemorrhage and necrosis of the atrioventricular node and His' bundle. The second brother presented fetal distress and polyhydramnios and the postnatal electrocardiogram revealed junctional ectopic tachycardia at a rate of 170 beats/min alternating with sinus rhythm, which was controlled without treatment.