Frequency and outcome of disorders of cardiac rhythm and conduction in a population of newborn infants.

Of 3,383 apparently healthy newborn infants studied in one region of England, 33 showed cardiac arrhythmias or preexcitation on a standard ECG. Twenty-six infants had multiple atrial or ventricular premature beats. One infant had atrial flutter, two had multifocal atrial tachycardia, and two had supraventricular tachycardia. Two infants showed the ECG pattern of the Wolff-Parkinson-White syndrome, but did not demonstrate cardiac arrhythmias. Performance of 24-hour ECG recordings of 15 of the 26 subjects with premature beats showed additional supraventricular or ventricular tachycardia in five cases. In one of two infants with multifocal atrial tachycardia, 24-hour recordings also demonstrated long episodes of rapid supraventricular tachycardia. Follow-up recordings (standard and 24-hour ECG) showed that in the majority of infants arrhythmias or preexcitation could not be demonstrated after 12 weeks of age. One infant with atrial premature beats, one infant with ventricular premature beats and ventricular tachycardia, and one infant with multifocal atrial tachycardia showed persisting arrhythmias. Four infants received antiarrhythmic therapy which probably influenced the natural history of their arrhythmias. Disorders of cardiac rhythm and conduction occur in apparently healthy infants. This study provides a basis for further prospective research into their natural history.