PII S0301-5629(98)00146-X ● Original Contribution CAROTID ARTERIAL STIFFNESS AS A SURROGATE FOR AORTIC STIFFNESS: RELATIONSHIP BETWEEN CAROTID ARTERY PRESSURE– STRAIN ELASTIC MODULUS AND AORTIC PULSE WAVE VELOCITY YOJI NAGAI,* JEROME L. FLEG, † MARY K. KEMPER, ‡ TOMASZ M. RYWIK, † CHRISTOPHER J. EARLEY ‡ and E. JEFFREY METTER* *Laboratory of Clinical Investigation, Gerontology Research Center, National Institute on Aging, National Institutes of Health; † Laboratory of Cardiovascular Science, Gerontology Research Center, National Institute on Aging, National Institutes of Health; and ‡ Department of Neurology, Johns Hopkins University Bayview Medical Center, Baltimore, MD (Received 5 February 1998; in final form 3 September 1998) Abstract—Common carotid arterial (CCA) stiffness can be assessed during carotid ultrasonography, but its association with aortic stiffness, a well-defined cardiovascular risk factor, has not been clarified. This study examines the relationship between CCA and aortic stiffness. CCA pressure–strain elastic modulus (Ep) and aortic pulse wave velocity (APWV) were evaluated in 110 healthy volunteers (age 56.2  14.6 y) by B-mode and Doppler ultrasonography. CCA Ep increased linearly with age and was higher in men than in women (model r 2  0.50, p < 0.001). APWV increased quadratically with age (model r 2  0.54, p < 0.001), similarly for women and men. Both CCA Ep and APWV were linearly associated with systolic blood pressure (BP) (r  0.53 and 0.46, respectively) but not with diastolic BP. A linear relationship was found between CCA Ep and APWV (APWV  194.7  5.67  Ep [model r 2  0.42, p < 0.001]). CCA Ep was associated with APWV (p < 0.001) independent of age, gender, and BP (model r 2  0.62, p < 0.001), and the most parsimonious model to explain APWV included CCA Ep and age (APWV  601.73  15.64  age  0.223  age 2  2.69  Ep [model r 2  0.60, p < 0.001]). Thus, CCA Ep is moderately associated with APWV. CCA stiffness as assessed by B-mode may be useful as a surrogate for aortic stiffness. © 1999 World Federation for Ultrasound in Medicine & Biology. Key Words: Common carotid artery, Aorta, Stiffness, Ultrasonics. INTRODUCTION AND LITERATURE Increased stiffness of large elastic arteries is thought to represent an early risk factor for cardiovascular disease (Arnett et al. 1994; Hodes et al. 1995; Lehmann 1996). Increased aortic stiffness mechanically leads to systolic blood pressure (BP) elevation (O’Rourke and Avolio 1980) and left ventricular hypertrophy (Nichols et al. 1985), both of which are well-established cardiovascular risk factors. Increased aortic stiffness also is associated with increasing age (Avolio et al. 1983), hypertension (Heints et al. 1993; Liu et al. 1989), diabetes (Airaksinen et al. 1993), hyperlipidemia (Lehmann et al. 1992), and smoking (Stefanadis et al. 1997). In addition, increased aortic stiffness is linked to the C allele of angiotensin II type I receptor polymorphism (Benetos et al. 1995), which increases the risk of myocardial infarction (Lud- wig et al. 1995). Increased aortic stiffness is reported in patients with coronary artery disease (Dart et al. 1991; Hirai et al. 1989) or stroke (Lehmann et al. 1995), and in healthy young adults with a family history of noninsulin- dependent diabetes mellitus (Hopkins et al. 1996). These findings suggest the potential utility of increased aortic stiffness in identifying individuals at higher cardiovas- cular risk. However, assessment of aortic stiffness cur- rently is limited to the research laboratory, largely due to a lack of convenient evaluation methods. Carotid ultrasonography is a commonly used clini- cal tool for diagnosing cerebrovascular disease (Eliasziw et al. 1995; Wityk et al. 1996) and allows for noninvasive determination of the common carotid arterial (CCA) stiffness by using B-mode (Barth et al. 1988; Lage et al. 1994) or M-mode (Barenbrock et al.; 1996 Gamble et al. 1994). Although CCA stiffness as assessed by these Address correspondence to: E. Jeffrey Metter, M.D., National Institutes of Health, National Institute on Aging, Gerontology Research Center, Box 06, Longitudinal Studies Section, 5600 Nathan Shock Drive, Baltimore, MD 21224-6825, U.S.A. E-mail: metterj@grc.nia. nih.gov Ultrasound in Med. & Biol., Vol. 25, No. 2, pp. 181–188, 1999 Copyright © 1999 World Federation for Ultrasound in Medicine & Biology Printed in the USA. All rights reserved 0301-5629/99/$–see front matter 181