A COMPARISON OF ATRIO-VENTRICULAR CONDUCTION IN NORMAL CHILDREN AND IN PATIENTS WITH RHEUMATIC FEVER, GLOMERULONEPHRITIS, AND ACUTE FEBRILE ILLNESSES
1. Atrio-ventricular conduction was studied in 50 normal children, 25 children with acute febrile illnesses, 50 patients with an initial episode of active rheumatic carditis, 46 patients with acute rheumatic fever without clinical evidence of carditis, and 39 children with acute post-streptococcal glomerulonephritis. 2. Quantitative measurements of A-V conduction were obtained by calculating the P-R index, the ratio between the recorded P-R interval (numerator) and the upper limit of normal for the age and heart rate as given in standard tables (denominator). 3. The mean P-R indices were similar in patients with acute rheumatic fever without clinical evidence of myocardial involvement and in children with overt carditis, and were significantly higher than in normal children, children with acute febrile illnesses of patients with acute glomerulonephritis. 4. The frequency with which high P-R indices were found in patients with acute rheumatic fever suggests that disturbances in A-V conduction are even more common than has been previously recognized from conventional P-R interval determinations. 5. The data suggest also that A-V conduction abnormalities in acute rheumatic fever occur independent of other signs of myocardial involvement and are not related to the ultimate prognosis.