The heart in normal infants and children

Summary 1. The physical signs, fluoroscopic, and electrocardiographic findings are described in a group of 260 presumably normal infants and children observed during the first fourteen years of life for a total of 1,264 patient years. The average period of observation was about five years. 2. During the first seven years of life, over 50 per cent of the patients presentedprecordial systolic murmurs. The murmur was heard each year in one or more examinations in 78 per cent. During the age span of 8 to 14 years, 66 per cent of the children presented murmurs. The murmur was heard each year in 58 per cent. Eighty-two per cent of the patients presenting murmurs in the first seven years of life retained these murmurs in subsequent years (up to the age of 14 years). 3. The cardiac silhouette was examined in the posterior-anterior and oblique views. The configuration was normal in the posterior-anterior view. In the left anterior oblique view, the angle of clearance of the left ventricle was 50 degrees ± in 90 per cent of the patients. In 10 per cent, sporadic angles of clearance of 55 degrees were observed, especially in obese children with high diaphragms. In the right anterior oblique position, none of the patients showed evidence of left auricular enlargement (absence of retrodisplacement of the esophagus using barium). 4. A total of 927 electrocardiographic tracings were studied. Averagevalues were obtained for the P-R interval (correlated with age and rate), the duration and amplitude of the P waves and QRS complexes, and for the amplitude of the T waves in the three leads. The corrected Q-T interval was obtained. Significant statistical differences were not obtained by comparison of patients with and without murmurs at various age levels. a. The P-R interval was found to be 0.14±0.02 second. During the first year of life it was 0.12±0.02 second. During the age span of 1 to 3 years with rates over 130 per minute, it was 0.13±0.02 second. Six per cent of the patients without murmurs showed sporadic P-R intervals greater than the upper limits. Twelve per cent of the patients with murmurs showed P-R intervals greater than the upper limits. In both groups, one third of the P-R prolongations equaled or exceeded twice the standard deviation. Forty-two per cent of the patients (representing 52 per cent of the tracings) showed fluctuations in consecutive P-R intervals greater than 0.02 second. b. The upper limits of amplitude of the P waves were 1.6, 2.3, and 1.6 mm. in Leads I, II, and III respectively. The lower limits of the P waves were 0.4, 0.3, and −0.4 mm. in the three leads. The upper limits of duration of the P waves were 0.07, 0.08, and 0.07 second in Leads I, II, and III, respectively. c. The upper limits of the amplitude of the T waves were 4-4, 5.7 (5.1 inthe first seven years of life), and 2.6 mm. in Leads I, II, and III, respectively. The lower limits of the T waves were 0.7, 1.7 (0.7 in the first seven years), and −1.8 mm. in the three leads. d. The average amplitude of the QRS complexes was found to be 11, 12.5,and 10.5 in Leads I, II, and III, respectively. The standard deviation was 4 to 5 mm. The upper limits of the duration of QRS2 was 0.08 second. e. The corrected Q-T interval (K in Bazett's formula) was found to range from 0.37 to 0.38±0.20 second. About 18 per cent of the patients presented sporadic electrocardiographicaberrations. These represented 10 per cent of the tracings. One half of the aberrations were P-wave changes. The remainder were divided between QRS and T-wave changes.