Junctional ectopic tachycardia in children: Electrocardiography, electrophysiology and pharmacologic response

Abstract

Junctional tachycardia due to an automatic ectopic focus occurs in children in one of two clinical settings: (1) in the immediate postoperative period after surgery, near the atrioventricular (A-V) junction, and (2) spontaneously, causing chronic supraventricular tachycardia. In the surface electrocardiogram, Junctional ectopic tachycardia appears as a narrow QRS tachycardia with A-V dissociation. This study evaluated four children, including two sisters, with Junctional ectopic tachycardia; intracardiac electrophysiologic recordings were performed in three of them. In each child, ventricular depolarization was preceded by a His bundle potential and a normal H-V interval. Neither overdrive pacing nor programmed premature stimulation of the atria or the ventricles influenced the tachycardia. Digoxin failed to alter the tachycardia, but alleviated congestive heart failure in all four patients. Propranolol slowed the rate of tachycardia in two patients, as did reserpine and phenytoin in one patient each. Chlorpromazine resulted in sinus rhythm in one patient. Quinidine and lidocaine were ineffective. Two patients died, one from low cardiac output associated with uncontrolled tachycardia, the other suddenly and unexpectedly while receiving digoxin and propranolol. The third patient's tachycardia regressed after repair of a ventricular septal defect. She has had sinus rhythm for 9 months without medication. The tachycardia of the fourth patient is uncontrolled despite treatment with digoxin, propranolol and phenytoin. On the basis of this study, acute treatment of Junctional ectopic tachycardia is recommended in the immediate postoperative period with intravenous propranolol (with a ventricular pacemaker available to treat bradycardia) and long-term treatment with oral digoxin plus either propranolol, phenytoin or Chlorpromazine.