Levels and rates of change in carotid-radial pulse wave velocity associated with reactive hyperaemia: Analysis of the dependence on transient ischemia length

The analysis of carotid-radial pulse wave velocity (PWVcr) changes in response to forearm transient ischemia (TI) has been proposed as an alternative approach to evaluate endothelial function. Consider flow mediated dilatation tests, PWVcr changes are characterized after 5 minutes of TI. It is unknown if lower TI times could be used and if different TI times would result in different PWVcr responses (levels and/or kinetics). Objective: To determine PWVcr changes associated with the reactive hyperemia in response to 1, 3 or 5 minutes of forearm TI. Methods: We measured left PWVcr change using mechano-transducers in healthy volunteers (22±2 years old) before (basal) and after 1 (n=14), 3 (n=14) and 5 (n=15) minutes of TI (forearm cuff inflation), respectively. The change of level and rate in PWVcr were recorded at 15, 30, 45 and 60 seconds after cuff release. Right brachial pressure was measured. Results: There were no changes in heart rate or blood pressure during the studies. Regardless of the occlusion length, TI resulted in PWVcr reduction (p<;0.05). The groups showed similar maximum PWVcr reduction. However, there were differences in the immediate PWVcr changes (-4.9±0.2%; -6.8±0.3% and -8.3±0.5% for 1, 3 and 5 minutes of TI, respectively) (p<;0.05). Then, the immediate rate of PWVcr change differed (p<;0.05) among the different ischemia times considered. Thereafter, the differences diminished and a minute after TI the groups showed similar levels and mean rate of PWVcr reduction. Conclusion: Similar maximum PWVcr responses can be obtained after 1, 3, or 5 minutes of TI. Different TI times resulted in dissimilar immediate, but not later, PWVcr changes.