Diurnal Variation of Pulse Wave Velocity Assessed Non-Invasively by Applanation Tonometry in Young Healthy Men

PURPOSE: Pulse wave velocity (PWV) is at least partially controlled by vascular tone. Vascular tone and underlying physiological processes such as sympathetic activity, plasma catecholamin, and cortisol levels have been shown to follow diurnal variations. MATERIALS AND METHODS: Carotid-to-radial PWV was non-invasively assessed by applanation tonometry in 21 young (26.5+/-2.3 years) healthy men at three different time points (8:00 hr, 12:00 hr, 17:00 hr) during a day. Additionally, heart rate, systolic, diastolic and mean blood pressure, and radial pulse pressure were assessed at the same time points. RESULTS: The mean PWV was significantly higher at 8:00 hr compared with the mean PWV assessed at later time points. No significant differences were found between mean PWV at 12:00 hr and at 17:00 hr. When PWV was corrected for blood pressure, the difference between values at 8:00 hr and 12:00 hr was no longer significant. Systolic, diastolic and mean blood pressure were significantly lower at 17:00 hr compared with those at 8:00 hr. CONCLUSION: A small but significant diurnal variation of PWV was observed in young healthy men, which might have been caused at least partly by variations of blood pressure. This finding could be of value, when PWV is used in human research. Thus, in longitudinal investigations the measurements should be performed at similar time points in the course of a day, in order to obtain comparable data. Additionally, our observations ought to be of assistance to studies in which novel pharmacological compounds with activity on the vasculature are investigated.