tiffness of large arteries has been related to cardiovascular mortality, but the mechanisms underlying this relationship have not been established. 1 Methods are used to estimate this stiffness include carotid ultrasound (CU) and pulse-wave-velocity (PWV). 2 Carotid artery stiffness detected by CU is known to representative of systemic arteriosclerosis. The measurement of PWV is very useful for diagnosing arteriosclerosis in any part of the body 3-7 and a new method for measuring PWV has been proposed in Japan. Brachial -ankle PWV (baPWV) measures the PWV in the arm and leg by applying air pressure using the volume plethysmographic method. However, baPWV is reportedly influenced by several factors such as blood pressure (BP), autonomic nerve function etc and therefore does not reflect arteriosclerosis in some cases.The stiffness parameter is reported to be independent of BP. 8 Beta of the thoracic descending aorta (TDA) has been obtained previously only by transesophageal echocardiography (TEE), 9 but recently this problem has been solved with the advent of the cardio-ankle vascular index (CAVI). CAVI is a new parameter that is also independent of BP 10-12 and in the present study, we examined the accuracy and usefulness of CAVI and compared it with other parameters of arteriosclerosis, using CU and serum lipids measurement in patients with chest pain syndrome.
Methods
Principle of CAVI and Method of MeasurementCAVI was obtained by substituting the stiffness parameter in the following equation for determining vascular elasticity and PWV. The stiffness parameter indicates BPindependent patient-specific vascular stiffness measured by arterial US. The stiffness parameter is calculated as: (1) where Ps and Pd are respectively the systolic and diastolic BP in mmHg. D is the diameter of the blood vessel and ∆D is the change of D.Bramwell-Hill's formula expresses the relationship between volume elastic modulus and PWV as follows:where ∆P is pulse pressure, is blood density, V is the volume of the blood vessel and ∆V is the change of V.From equation (2), the following formula is derived:where D is the diameter of the blood vessel and ∆D is the change of D. If we substitute equation (3) for equation (1), we obtain the stiffness parameter:CAVI is measured as follows. PWV is obtained by dividing vascular length (L) by the time (T) taken for the pulse wave to propagate from the aortic valve to the ankle Circ J 2007; 71: 1710 -1714 (Received February 15, 2007 revised manuscript received June 20, 2007; accepted July 4, 2007) Division of Cardiology, Tokuyama Central Hospital, Shunan, *Division
Methods and ResultsThe purpose of this study was to evaluate the accuracy and usefulness of CAVI and to compare it with other parameters of arteriosclerosis by carotid ultrasound (CU). The instantaneous dimensional change of the TDA on TEE was measured simultaneously with systemic pressure of the brachial artery in 70 patients in sinus rhythm. There were significant correlations between CAVI and age (r=0.65, p<0.01), and CAVI and...
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