Sample size estimates were obtained based on prior data that show that ascending- descending PWV measured by CMR is 3.3±0.6 m/s in normal subjects and 4.7±1.1 m/sec after CoA surgery.22, 70 Sample size estimates for comparison of PVW between three equal sized treatment groups (assuming overall significance level=0.05 and power=0.8) are shown in table 2. The investigators plan on recruiting 24 to 30 patients in each group for a total sample size of 72 to 90.