Influence of body height on aortic systolic pressure augmentation and wave reflection in childhood.

The enhanced wave reflection in small children is a well-known phenomenon. It is explained on the basis of differences in the body height and the timing of wave reflection. This hypothesis still has not been proved directly. The aim of our study was to determine the reference values of aortic augmentation index (Aix(ao)) and the simultaneously measured return time of the systolic pulse wave (RT) in relation to the body height to test this hypothesis. Aix(ao) and RT were measured by Arteriograph in a healthy population aged 3-18 years (n = 4619, 2489 males). The Aix(ao) decreased with increasing age in boys from 18.6 ± 8.4% to 4.7 ± 4.3% and in girls from 22.3 ± 9.2% to 8.1 ± 5.1%, whereas the RT increased from 115.5 ± 16.3 ms to 166.7 ± 20.8 ms in boys and from 106.7 ± 21.9 ms to 158.1 ± 15.5 ms in girls. These changes were constant during childhood, but they slowed down after the onset of puberty. Because aortic pulse wave velocity (PWV(ao)) measured in the same population was unchanged during childhood, the increase of RT can only be explained by the increase of aortic length due to growth. In the puberty PWV(ao) starts increasing indicating that RT (Aix(ao)) does not follow the increase (decrease) of aortic length proportionally.