Chronic supraventricular tachycardia in infancy and childhood.

The results of a one to 19 year follow-up study of 9 children with supraventricular tachycardia of more than one month's duration are reported. The ECG diagnosis of tachycardia was made before birth in one patient and between the ages of 8 months and 12 years in 8. Four had sustained and 4 had repetitive tachycardia, while one patient had both patterns at different times. Reciprocal rhythm was diagnosed in 3 patients and exit block in 2. Severe symptoms had occurred in 2 patients, but as a rule symptoms were mild or absent. No treatment abolished the arrhythmias but digitalis reduced the overall ventricular rate in 6 patients. After a duration of 1-7 years, 3 patients still had tachycardia at the follow-up. In the remaining 6 patients the tachycardia had subsided 7 months to 10 years after the onset.