A Novel Blood Pressure-independent Arterial Wall Stiffness Parameter; Cardio-Ankle Vascular Index (CAVI)

To measure the stiffness of the aorta, femoral artery and tibial artery noninvasively, cardio-ankle vascular index (CAVI) which is independent of blood pressure was developed. The formula for measuring this index is; CAVI=a (2rho/DeltaP) x ln (Ps/Pd) PWV (2) + b where, Ps and Pd are systolic and diastolic blood pressures respectively, PWV is pulse wave velocity between the heart and ankle, DeltaP is Ps - Pd, rho is blood density, and a and b are constants. This equation was derived from Bramwell-Hill's equation (1) ), and stiffness parameter (2) ). To elucidate the clinical utility of CAVI, the reproducibility and dependence on blood pressure were studied using VaSera (Fukuda Denshi Co. , Ltd. ). Furthermore, CAVI in hemodialysis patients with or without atherosclerotic diseases was measured. The average coefficient of variation for five measurements among 22 persons was 3. 8%. In hemodialysis patients (n = 482), CAVI was correlated weakly with systolic and diastolic blood pressures (R = 0. 175, 0. 006), while brachial-ankle PWV was correlated strongly with systolic and diastolic blood pressures (R = 0. 463, 0. 335). CAVI in hemodialysis patients without signs of atherosclerotic diseases (NA) was 8. 1 +/- 0. 3 (mean +/- SD). That in patients receiving percutaneous transluminal coronary angioplasty was 8. 8 +/- 0. 3 (p < 0. 05 vs. NA). CAVI in patients with ischemic change in their electrocardiogram (ECG) was 8. 5 +/- 0. 3 (p < 0. 05 vs. NA). That in patients with diabetes mellitus was 8. 5 +/- 0. 3 (p < 0. 002 vs. NA). CAVI in the patients with all three complications was 8. 9 +/- 0. 35 (p < 0. 001 vs. NA). These results suggested that CAVI could reflect arteriosclerosis of the aorta, femoral artery and tibial artery quantitatively.