The Q-T Interval in Normal Infants and Children

Abstract

Because of renewed clinical interest in the Q-T interval and because of a need of normal values for an accompanying investigation in rheumatic fever, the Q-T was studied in 517 normal infants and children from birth to 13 years of age. A mean K of 0.404 for Bazett's formula and of 0.378 for Ashman and Hull's formula was obtained. With Bazett's curve approximating the data more closely, a Bazett's scattergram of the normal Q-T at varying heart rates was constructed. Although no difference in K value was noted between the sexes, significant differences were observed in certain age groups.

Prolongation of the QT Interval and the Sudden Infant Death Syndrome

“…Most previous studies have been of older infants or have included fewer electrocardiograms. 9,[13][14][15] In the study by Southall et al, which is an exception to this pattern, 16 most electrocardiograms were recorded before the third day, when The mean heart rate and QTc were similar to those previously reported during the first week of life. 9,13,14 Among adults, women have a longer QTc than men, 17 but in a previous study of neonates, we found no difference according to sex.…”

Hyperventilation in the awake state: potentially treatable component of Rett syndrome.

“…None had apnoeic pauses exceeding 19 seconds. Two further breathing patterns were identified: firstly, episodes of periodic apnoea were seen in 15 of the 23 (65%) controls (durations 0.05 to 0 75 minutes/hour of recording: median duration of those with periodic apnoea 0.13 minutes/hour). Only one of the 18 patients with Rett syndrome (case 13) had no periodic apnoea.…”

False "Coronary Patterns" in the Infant Electrocardiogram

“…3, [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] showed as the outstanding abnormality all ST-T deviation of discordant type. Ill leads I, aVr, and V4 to Vr,, the kS-T was mitarkedly\ elevated in contrast to equally prominent S-T depression in Il, III, aVF, and V1~to V,.…”

“…A left aortic arch was seen to originate from the left ventricle, and a tiny pulmonary artery appeared to communicate with the right ventricle. The [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] showed an unchanged sinus rate and P-R interval. The precordial leads revealed prominent R waves with an upright T wave in the right precordial leads and predominant S waves in the left, suggesting right ventricular hypertrophy.…”