Vasoactive drugs influence aortic augmentation index independently of pulse-wave velocity in healthy men

Aortic augmentation index, a measure of central systolic blood pressure aug mentation arising mainly from pressure-wave reflection, increases with vasc ular aging. The augmentation index is influenced by aortic pulse-wave veloc ity (related to aortic stiffness) and by the site and extent of wave reflec tion. To clarify the relative influence of pulse-wave velocity and wave ref lection on the augmentation index, we studied the association between augme ntation index, pulse-wave velocity, and age and examined the effects of vas oactive drugs to determine whether altering vascular tone has differential effects on pulse-wave velocity and the augmentation index. We made simultan eous measurements of the augmentation index and carotid-to-femoral pulse-wa ve velocity in 50 asymptomatic men aged 19 to 74 years at baseline and, in a subset, during the administration of nitroglycerin, angiotensin Il, and s aline vehicle. The aortic augmentation index was obtained by radial tonomet ry (Sphygmocor device, PWV Medical) with the use of an inbuilt radial to ao rtic transfer function. In multiple regression analysis, the aortic augment ation index was independently correlated only with age (R=0.58, P <0.0001). Nitroglycerin (3 to 300 mug/min IV) reduced the aortic augmentation index from 4.8 +/-2.3% to -11.9 +/-5.3% (n=10, P <0.002). Angiotensin II (75 to 3 00 ng/min IV) increased the aortic augmentation index from 9.3 +/-2.4% to 1 8.3 +/-2.9% (n=12, P <0.001). These drugs had small effects on aortic pulse -wave velocity, producing mean chan ges from baseline of <1 m/s (each P <0. 05). In healthy men, vasoactive drugs may change aortic augmentation index independently from aortic pulse-wave velocity.