Validation of Carotid Artery Tonometry as a Means of Estimating Augmentation Index of Ascending Aortic Pressure

• Published in: Hypertension (Dallas, Tex. 1979) Tex. 1979), 1996-02, Vol.27 (2), p.168-175
• Main Authors: Chen, Chen-Huan, Ting, Chih-Tai, Nussbacher, Amit, Nevo, Erez, Kass, David A., Pak, Peter, Wang, Shih-Pu, Chang, Mau-Song, Yin, Frank C.P.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Aorta, Thoracic - physiology; Aorta, Thoracic - physiopathology; Biological and medical sciences; Blood Pressure - drug effects; Cardiac Catheterization; Cardiomyopathy, Hypertrophic - physiopathology; Cardiovascular Diseases - physiopathology; Cardiovascular system; Carotid Arteries - physiology; Carotid Arteries - physiopathology; Child; Coronary Disease - physiopathology; Diastole; Female; Heart Defects, Congenital - physiopathology; Heart Rate; Heart Valve Diseases - physiopathology; Humans; Hypertension - physiopathology; Investigative techniques of hemodynamics; Investigative techniques, diagnostic techniques (general aspects); Male; Manometry - methods; Medical sciences; Middle Aged; Nitroglycerin - pharmacology; Physical Exertion; Reference Values; Systole
• ISSN: 0194-911X; 1524-4563
• DOI: 10.1161/01.hyp.27.2.168

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 Unites 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 plus/minus SD and correlation coefficients were baseline (14 plus/minus 16, 28 plus/minus 17, .77), handgrip (18 plus/minus 19, 32 plus/minus 15, .86), and nitroglycerin (7 plus/minus 12, 18 plus/minus 13, .52). In addition, after adjusting for age, sex, height, blood pressure, heart rate, and study site, the changes of both Als 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. (Hypertension. 1996;27:168-175.).