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{(2ρ/ΔP) × ln(Ps/Pd)PWV2} + b where, Ps and Pd are systolic and diastolic blood pressures respectively, PWV is pulse wave velocity between the heart and ankle, ΔP is Ps − Pd, ρ is blood density, and a and b are constants. This equation was derived from Bramwell-Hill’s equation1), and stiffness parameter2). 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.
Arterial stiffness has been known to be a surrogate marker of arteriosclerosis, and also of vascular function. Pulse wave velocity (PWV) had been the most popular index and was known to be a ...predictor of cardiovascular events. But, it depends on blood pressure at measuring time. To overcome this problem, cardio-ankle vascular index (CAVI) is developed. CAVI is derived from stiffness parameter β by Hayashi, and the equation of Bramwell-Hill, and is independent from blood pressure at a measuring time. Then, CAVI might reflect the proper change of arterial wall by antihypertensive agents. CAVI shows high value with aging and in many arteriosclerotic diseases and is also high in persons with main coronary risk factors. Furthermore, CAVI is decreased by an administration of α1 blocker, doxazosin for 2-4 hours, Those results suggested that CAVI reflected the arterial stiffness composed of organic components and of smooth muscle cell contracture. Angiotensin II receptor blocker, olmesartan decreased CAVI much more than that of calcium channel antagonist, amlodipine, even though the rates of decreased blood pressure were almost same. CAVI might differentiate the blood pressure-lowering agents from the point of the effects on proper arterial stiffness. This paper reviewed the principle and rationale of CAVI, and the possibilities of clinical applications, especially in the studies of hypertension.
Objects
The purpose of this study was to calculate robust quantitative estimates of the predictive value of cardio-ankle vascular index, (CAVI) for future all-cause mortality in hemodialysis ...patients.
Subjects and methods
A total of 163 hemodialysis patients (102 males and 61 females, mean age 60±11 years), who had the examination of CAVI between 2004 and 2005 at Mihama Narita Clinic, Chiba ,Japan, were included and followed up for 80 months. Those had diabetes mellitus (27.0%), hypertension (77.3%) or/and dyslipidemia (36.8%). CAVI was measured using Vasela1500 (Fukuda Denshi. Co.LTD).
Results
Among 163 hemodialysis patients, 51 deaths were observed in 6.5 years. Causes of death were heart disease (37.3%), brain stroke (19.6%), infection (17.6%), suffocation (3.9%) and others. In subjects with death, higher CAVI (9.3±1.8 vs. 8.3±1.2), mean age (65±12 vs. 57±10 years) and prevalence of diabetic nephropathy (43.1 vs. 19.6%) were observed.
COX proportional-hazards regression analysis of the association between death and clinical variables showed that high CAVI (≥10) independently increased the risk of death with OR of 2.605 (95% CI 1.321–5.141, P=0.006). OR of Diabetic nephropathy was 2.027(95%CI 1.102–3.727, P=0.023) and OR of elderly (≥65 years) was 3,152, (95%CI 1.758–5.649, P<0.0001).
Kaplan-Meier curves for cumulative survival in hemodialysis patients stratified by severity of CAVI(8>, 9>,10>, 10<) showed that the survival rates on the patients with higher CAVI groups were significantly low (P = 0.002, Log-rank test).
Conclusion
CAVI is an independent predictor of death in hemodialysis patients.
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GEOZS, NUK, OILJ, SBJE, UL, UM, UPUK
Mortality rate of maintenance hemodialysis patients is known to be high. Cardio-ankle vascular index (CAVI) is an index reflecting the proper stiffness of the arterial tree from the origin of the ...aorta to the ankle. We aimed to clarify the utility of CAVI as a predictor of mortality in hemodialysis patients. The roles of age and nutritional conditions on survival were also examined.
We followed 242 patients undergoing hemodialysis for 6 consecutive years. Data from 209 patients (mean age was 60 ± 11 years) excluding those with ankle-brachial index <0.90 were then analyzed. CAVI and heart to ankle pulse wave velocity (haPWV) were measured using Vasera 1500.
Thirty-eight hemodialysis patients who died during the 6-year period had higher age, cardiothoracic ratio (CTR), CAVI, and haPWV, and lower diastolic blood pressure, albumin, phosphate, and calcium phosphate product. The Kaplan-Meier curves for cumulative survival among the tertile groups showed that the mortality rate was higher in the highest tertile (T3) compared to T1/T2 for both CAVI and haPWV. Receiver operating characteristic (ROC) analysis revealed that CAVI had better discriminatory power for all-cause mortality compared to haPWV. In the Cox-proportional hazards analyses, 1 SD increase in both parameters contributed independently to all-cause mortality CAVI: HR 1.595 (95% CI 1.108-2.297), haPWV: HR 1.695 (95% CI 1.185-2.425), as well as age and CTR. Both parameters above the cut-offs estimated in the ROC analysis (CAVI ≥ 9.2, haPWV ≥ 8.9) also had independent contributions to mortality.
Through the 6 consecutive years of follow-up in 209 HD patients, increased CAVI might represent a major modifiable risk factor for all-cause mortality. Further research is needed to examine whether CAVI-lowering interventions contribute to improved prognosis.
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