Normalized pulse transit time to assess age- related changes

Pulse wave velocity (PWV) is a physiologic measure that has shown to be clinically important in the assessment of increased arterial stiffness that is linked to systolic hypertension. Studies have indicated that there is age-related increase in PWV for the pediatric population. Pulse transit time (PTT) which is based on the principle of PWV has become popular in cardiovascular studies. However, PTT (a time-related inverse equivalent of PWV) also increases with age during childhood. Much of this PTT increase is believed to be contributed by the age-related growth of the measured periphery. Limited study has been conducted to understand this aspect of the PTT-PWV relationship. 55 healthy children (39 male) aged 8.4 plusmn 2.3 yr were recruited to understand the effect of peripheral path length on PTT. All measured arm and leg length were normalized to reference values of their given age and gender. PTT in its natural form increases with age for finger and toe sites by (slope plusmn 95% confidence interval of +6.08 plusmn 1.19; R value of 0.815) and (+6.70 plusmn 1.74; 0.727) respectively while its normalized values decreases with age by (-6.02 plusmn 1.91; 0.654) and (-7.96 plusmn 2.48; 0.663) accordingly. Preliminary results herein suggest that PTT increases with the body growth but this increase may be attenuated by a concomitant age-related increase in PWV. Thereby, it causes the overall PTT to increase during childhood. This finding provides further understanding in the PTT-PWV association.