Assessment of variables affecting flow propagation velocity of the left ventricle in healthy children

Background: The purpose of the present study was to establish the normal values of flow propagation velocity (FPV) in healthy children and examine the variables that affect FPV in clinical situations. Methods: Two hundred and thirty- five healthy children and adolescents were assessed (aged 0-22.6 years, mean age 7.4 ± 5.4 years; male, n = 142; female, n = 93). FPV was obtained from an apical four-chamber view and determined as the slope of aliasing velocity of early diastolic transmitral flow on the color M-mode using Aloka SSD-5500 with 5.0 MHz transducer. Aliasing velocity was set at 50-70% of the peak transmitral flow velocity. Peak transmitral flow velocities in early diastole (E) and during atrial contraction (A), and the ratio of early to late peak velocity (E/A) were obtained. Tei index was also measured for analysis of general left ventricular performance. Left ventricular mass index (LVMI) was obtained from conventional echo measurement. E, E/A, Tei index and LVMI were compared with FPV in healthy subjects. Results: FPV obtained from all subjects ranged from 23.7 to 96.0 cm/s (61.3 ± 13.6 cm/s). Normal value of FPV was less dependent on age, body size, heart rate and left ventricular dimension. In contrast, although there was no significant correlation between FPV and ejection fraction, statistically significant correlation was found between FPV, LVMI (P = 0.0008) and Tei index (P = 0.025). Conclusions: FPV is independent of age, body size and heart rate and is useful to assess left ventricular relaxation in children.