A group of 85 children between i and 21 years, subdivided into 4 age groups (mean 3,6, 7*4, II 9, and 17 5 years) without known cardiovascular disorders was investigated. Left ventricular ejection time and preejection period were calculated from the electrocardiogram, phonocardiogram, and external carotid pulse wave, obtained in the supine position at rest. Pulse wave transmission times derived from external arterial pulsation tracings, were calculated for extremities and central aorta.

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... n tracings were recorded with a specially designed pulse wave transducer. In the younger age groups (3-6, 7 4, and I g9years), left ventricular ejection times correctedfor heart rate did not differ significantly from adult values. In the highest age group (mean 17 5 years), mean ejection times tended to be shorter. The pre-ejection period corrected for heart rate was significantly shorter, compared to adults (P< o ooI), in the age groups 3 6, 7 -4, and II-9 years, whereas in the group 17 5 years no statistically significant difference was found. Pulse wave velocities calculated from pulse wave transmission times in the arm and central aorta decrease from birth to the age of 8 years, after which a gradual rise occurs which continues into adult life. In the leg the initial decrease is absent. Subjects and methods Systolic intervals Data were obtained from a group of 85 children with normal cardiovascular systems, selected from the patients of a general paediatric ward shortly before their release from hospital. The children were all in good health at the time of investigation, convalescing from minor diseases, mostly infectious, and were not confined to their beds. Careful paediatric examination had not revealed any cardiac pathology. Mean values for height and weight in relation to age of the group conformed to the value in the general Dutch population, with a confidence limit of 95 per cent. on 26 April 2019 by guest. Protected by copyright.