The purpose of this intra-agency agreement (Y02-AG-5-0282) is to support the measurement of arterial pulse wave velocity as a measure of arterial stiffness in the NHLBI Activity Counseling Trial (ACT). The trial is designed to test the hypothesis that increases in physical activity resulting from educational interventions will reduce arterial stiffness. The setting is appropriate for this hypothesis testing because of the prospective nature of the study and the range of interventions which will be adopted. The measurements will be taken at three points in time when other physiologic measures are taken. This will allow assessment of intra-individual variability as well as the possibility of examining change over time in these measures in relation to the level of compliance with the physical activity intervention. The study is taking place in three geographic locations to assure adequate sample size for subgroup analysis: Memphis, TN, Dallas, TX and Palo Alto, CA. Pulse wave velocity is being measured by two Doppler flow velocity probes simultaneously measuring the carotid and femoral arteries. A computer algorithm calculates average flow velocity tracings on a beat-to-beat basis. The time needed for the pressure wave to travel from the proximal to distal sampling site is calculated from the foot of the pressure wave. Although there was an initial delay in patient recruitment in the early months of the study, each site is now operating at a higher level. The most recent recruitment report indicates that approximately 200 patients have been examined in the three clinics. A sizable number of patient records have been reviewed by the cardiologist for quality of the pulse wave velocity tracings. Recruitment will continue over the next several months, and second visits will follow at approximately 6 months after completion of the baseline, with a final measurement taken at approximately 24 months subsequent to baseline.
| Havlik, R J; Brock, D; Lohman, K et al. (2001) High-density lipoprotein cholesterol and vascular stiffness at baseline in the activity counseling trial. Am J Cardiol 87:104-7, A9 |
