Left ventricular diastolic function in infants, children, and adolescents. Reference values and analysis of morphologic and physiologic determinants of echocardiographic Doppler flow signals during growth and maturation

Objectives. The aim of this study was to set up reference values for Doppler flow-derived left ventricular filling parameters and to evaluate physiologic determinants of changes in signal expression related to maturation. Background. In left ventricular diastolic function studies, age-related modulations in signal expression are observed. Assuming degenerative myocardial changes to be absent during childhood and adolescence, the determinants of these modulations must be different from those suspected in adults. Methods. Pulsed wave Doppler signals from the mitral valve tip region were recorded in 329 healthy subjects aged 2 months to 39 years. Multiple linear regression was used to evaluate statistical relations between Doppler flow signals and stroke volume in the mitral valve area. Results. Increasing early filling time velocity integral throughout maturation caused decrease in atrial filling fraction from 0.34 ± 0.06 to 0.24 ± 0.04 (p < 0.005). Peak flow velocities during atrial systole decreased from infancy to adolescence (66 ± 15 to 41 ± 10 cm/s). Main effects on signal modulation were caused by heart rate, stroke volume and mitral ring are with linear model fit (R2) of 0.79 for early filling phase (E)-time velocity integral, 0.6 for atrial filling phase peak velocity 0.84 for total E duration and 0.73 for E deceleration time. Atrial filling phase-time velocity integral, albeit significantly dependent on heart rate, was stable throughout growth. Conclusions. During infancy and childhood, the stroke volume crossing the mitral valve is main modulator for early filling phase (E)-time velocity integral and diastolic time intervals during early filling, whereas atrial filling phase parameters are mainly dependent on heart rate. This results in more pronounced atrial filling during infancy and childhood.