Multifocal or chaotic atrial rhythm: report of nine infants, delineation of clinical course and management, and review of the literature.

Nine infants with episodic or continuous chaotic atrial rhythm (CAR) are presented. In addition to 3 or more different P-wave contours, atrial rates greater than 100 per minute, variable PP, RR, and PR intervals, and a discrete isoelectric baseline, findings included atrial rates that varied from a low of 50 to 120 to a high of 140 to 270 per minute, ventricular rates that varied from a low of 40 to 50 to a high of 180 to 270 per minute, and periodic sinus arrest with junctional escape rhythm. Except for the arrhythmia, all had a normal cardiac examination, ECG, chest x-ray film, and echocardiogram. Six infants were otherwise normal; one had an orbital rhabdomyosarcoma; one had neonatal asphyxia; and one had respiratory distress, bronchopulmonary dysplasia, and an intraventricular cerebral hemorrhage. The CAR persisted from 3 days to 20 months; it spontaneously reverted to normal sinus rhythm in 8 infants and persists in 1 infant at age 7 months. Digoxin (4 patients), propranolol hydrochloride (3 patients), quinidine sulfate (2 patients), and lidocaine (1 patient) did not alter the CAR. No patient had heart failure secondary to the CAR, although three also had episodes of sustained atrial tachycardia, which while present caused heart failure. All patients are functioning normally at home and have normal findings on cardiac examination and have normal ECGs at ages 3 to 38 months. Seven are in normal sinus rhythm, one has rare atrial premature contractions, and one has persistent CAR. We conclude that specific treatment was not necessary in these infants with CAR, except in those with associated sustained atrial tachycardia, which itself may cause heart failure.