title: Validation of carotid artery tonometry as a means of estimating augmentation index of ascending aortic pressure.
abstract: Our objective was to validate a carotid artery tonometry-derived augmentation index as a means to estimate augmentation index (AI) of ascending aortic pressure under various physiological conditions. A total of 66 patients (50 men, 16 women; mean age, 55 years; range, 21 to 78 years; 44 in Taiwan and 22 in the United States) undergoing diagnostic catheterization were studied. Arterial pressure contours were obtained simultaneously from the right common carotid artery by applanation tonometry with an external micromanometer-tipped probe and from the ascending aorta by a micromanometer-tipped catheter at baseline (n = 62), after handgrip (n = 36), or after sublingual nitroglycerin administration (n = 17). The AI (expressed as percentage values) was calculated as the ratio of amplitude of the pressure wave above its systolic shoulder to the total pulse pressure. The carotid AI was consistently lower than the aortic AI, but the two were highly correlated at baseline and after both handgrip and nitroglycerin. Mean +/- SD and correlation coefficients were baseline (14 +/- 16, 28(+) +/- 17, .77), handgrip (18 +/- 19, 32(+) +/- 15, .86), and nitroglycerin (7 +/- 12, 18(+) +/- 13, .52). In addition, after adjusting for age, sex, height, blood pressure, heart rate, and study site, the changes of both AIs from baseline values with handgrip or nitroglycerin were highly associated such that the aortic AI could be approximated from the carotid AI with appropriate regression equations. The high correlations and predictable changes after interventions between the central AI and those estimated from noninvasive carotid tonometry suggest that this technique may have wide applicability for many cardiovascular studies.
authors.affiliation: Department of Medicine, Veterans General Hospital-Taipei, Republic of China.
authors.forename: C H
authors.initials: CH
authors.lastname: Chen
authors.forename: C T
authors.initials: CT
authors.lastname: Ting
authors.forename: A
authors.initials: A
authors.lastname: Nussbacher
authors.forename: E
authors.initials: E
authors.lastname: Nevo
authors.forename: D A
authors.initials: DA
authors.lastname: Kass
authors.forename: P
authors.initials: P
authors.lastname: Pak
authors.forename: S P
authors.initials: SP
authors.lastname: Wang
authors.forename: M S
authors.initials: MS
authors.lastname: Chang
authors.forename: F C
authors.initials: FC
authors.lastname: Yin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001013:Aorta, Thoracic / Q000502:physiology / Q000503:physiopathology*; D001794:Blood Pressure / Q000187:drug effects; D006328:Cardiac Catheterization; D002312:Cardiomyopathy, Hypertrophic / Q000503:physiopathology; D002318:Cardiovascular Diseases / Q000503:physiopathology*; D002339:Carotid Arteries / Q000502:physiology / Q000503:physiopathology*; D002648:Child; D003327:Coronary Disease / Q000503:physiopathology; D003971:Diastole; D005260:Female; D006330:Heart Defects, Congenital / Q000503:physiopathology; D006339:Heart Rate; D006349:Heart Valve Diseases / Q000503:physiopathology; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D008297:Male; D008365:Manometry / Q000379:methods; D008875:Middle Aged; D005996:Nitroglycerin / Q000494:pharmacology; D005082:Physical Exertion; D012016:Reference Values; D013599:Systole
chemical_list: D005996:Nitroglycerin