Increase in cardiac contractility during puberty.

Pubertal growth of heart was analyzed. Growth rates of "diastolic variables" of heart size were compared with that of 'systolic', and both with growth intensities of some body structures and functions that are related to cardiac growth. Longitudinal echocardiographic, ergometric and anthropometric measurements were performed in 84 healthy boys, aged 11.5 years at the beginning and 14.5 at the end of study. Diastolic thickness of left ventricular walls increased by a mean rate of 15% and systolic by 36% (p < 0.001). As a result, percent systolic wall thickening increased from 20% to 41% during the 3 years (p < 0.001). Other measures of cardiac contractility increased in the same manner. Increase in measures of cardiac preload and afterload corresponds to the increase in heart "diastolic" and "systolic" variables, respectively. The study gave evidences for an increase in cardiac contractility during puberty. Coexistence of two simultaneous growth models for pubertal heart: diastolic and systolic, is suggested.