A novel blood pressure-independent arterial wall stiffness parameter; cardio-ankle vascular index (CAVI)

Cardio-ankle vascular index is superior to brachial-ankle pulse wave velocity as an index of arterial stiffness

Both cardio-ankle vascular index (CAVI) and brachial-ankle pulse wave velocity (baPWV) are noninvasive methods to estimate arterial stiffness. The purpose of this study is to determine whether CAVI or baPWV is superior as an index of arterial stiffness. One hundred and thirty patients with chest pain syndrome who underwent coronary angiography (CAG) were included in this study. We obtained intima-media-thickness (IMT) and the stiffness parameter beta of the carotid artery by carotid ultrasounds (CU). The peak early diastolic velocity (E), deceleration time of E (EDCT), peak atrial systolic velocity (A) of transmitral flow and left ventricular mass index (LVMI) were obtained by echocardiography. CAVI, baPWV, total cholesterol (T-C), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C) and triglycerides (TG) were measured before CAG. There was a significant correlation between CAVI and baPWV (r = 0.64, p < 0.01). Both CAVI and baPWV were significantly correlated with age, IMT and beta (age: r = 0.64, p < 0.01 for CAVI, and r = 0.48, p < 0.01 for baPWV; IMT: r = 0.40, p < 0.01, and r = 0.31, p < 0.01; beta: r = 0.36, p < 0.01 and r = 0.25, p < 0.01). However, only CAVI was correlated with the parameters of left ventricular diastolic indices from echocardiography (E/A: r = 0.44, p < 0.01; EDCT: r = 0.36, p < 0.01). Additionally, LDL-C and T-C/HDL-C were also associated with only CAVI (LDL-C: r = 0.26, p < 0.02; T-C/HDL-C: r = 0.30, p < 0.01), not baPWV. Finally, only CAVI was significantly higher in the group with angina pectoris than in the normal group (9.708 +/- 1.423 vs. 9.102 +/- 1.412; p = 0.0178). All parameters associated with atherosclerosis suggested that CAVI was superior to baPWV as a parameter of arterial stiffness.

Relative Effects of Telmisartan, Candesartan and Losartan on Alleviating Arterial Stiffness in Patients with Hypertension Complicated by Diabetes Mellitus: An Evaluation Using the Cardio-Ankle Vascular Index (CAVI)

Using the cardio-ankle vascular index (CAVI) as an indicator, we assessed improvement of arterial stiffness in 95 outpatients with hypertension complicated by type 2 diabetes mellitus who were treated orally for ≤ 12 months with telmisartan 40 mg/day, losartan 50 mg/day or candesartan 8 mg/day. At 1 year, in the telmisartan and losartan groups CAVI did not change whereas in the candesartan group CAVI showed a statistically significant decrease of 2.70%. Although telmisartan is believed to enhance the activity of peroxisome proliferator-activated receptor (PPAR-γ) in vitro, it did not ameliorate arterial stiffness in our patients. Candesartan, however, improved arterial stiffness independently of blood pressure lowering and without PPAR-γ agonist action, possibly by direct action resulting from its potent affinity and binding capacity for the angiotensin II type 1 receptor. We conclude that candesartan is a potentially useful therapy against arterial stiffness in hypertensive patients with type 2 diabetes mellitus.

Relationship of cardio-ankle vascular index (CAVI) to carotid and coronary arteriosclerosis

BACKGROUND

The cardio-ankle vascular index (CAVI) has been recently reported as a new index of aortic stiffness, which is less influenced by blood pressure than pulse wave velocity (PWV). The present study investigated the relationship between the levels of CAVI and carotid and coronary arteriosclerosis.

METHODS AND RESULTS

The 443 consecutive patients who underwent CAVI, carotid sonography, and coronary angiography in hospital were examined. Intima-media thickness (IMT) and carotid plaque were evaluated by ultrasonography. The severity of coronary artery disease (CAD) was evaluated by coronary angiography and the subjects were divided into 4 groups (0, no significant organic stenosis: 1, 1-vessel disease: 2, 2-vessel disease: 3, 3-vessel disease). Univariate analyses showed that both CAVI and brachial-ankle PWV (baPWV) were associated with IMT and the presence of carotid plaque. Multiple stepwise regression analyses revealed that CAVI (p=0.0427), but not baPWV, was associated with the IMT. Both CAVI (p<0.0001) and baPWV (p=0.0140) were significantly associated with the severity of CAD. Multiple logistic analyses revealed that CAVI (p=0.0342), but not baPWV (p=0.8027), was associated with the presence of multivessel disease.

CONCLUSION

High CAVI implies progression of carotid and coronary arteriosclerosis. CAVI may be more closely linked with arteriosclerosis than baPWV.

Cardio-ankle vascular index and ankle pulse wave velocity as a marker of arterial fibrosis in kidney failure treated by hemodialysis

BACKGROUND

Patients with kidney failure treated with hemodialysis have a high incidence of cardiovascular diseases caused by accelerated arteriosclerosis. However, accurate evaluation of the extent of arteriosclerosis is difficult. This study sought to compare the strength of predictions of arterial fibrosis by using a new parameter, the cardio-ankle vascular index (CAVI), versus pulse wave velocity (PWV) in patients with kidney failure treated with hemodialysis.

STUDY DESIGN

Diagnostic test study.

SETTING & PARTICIPANTS

103 patients with kidney failure undergoing surgical construction of an arteriovenous access for hemodialysis therapy.

INDEX TEST

CAVI and PWV.

REFERENCE TEST

Arterial fibrosis, evaluated by using Masson trichrome stain on part of the brachial artery obtained during surgery, expressed as percentage of fibrosis of the layer of vascular smooth muscle cells.

RESULTS

Median percentage of arterial stiffness was 52.85%. Mean PWV and CAVI were 18.3 +/- 5.6 (SD) m/s and 9.9 +/- 2.6, respectively. Multivariate regression analysis showed that arterial fibrosis was significantly associated with older age (0.247%/y; 95% confidence interval, 0.013 to 0.482) and CAVI (6.117%/unit; 95% confidence interval, 4.764 to 4.740), but not with systolic blood pressure (0.039%/mm Hg; 95% confidence interval, -0.076 to 0.153) or PWV (-0.044%/m/s; 95% confidence interval, -0.646 to 0.558). The area under the receiver operating characteristic curve to predict greater than median percentage of arterial stiffness was 0.892 for CAVI and 0.779 for PWV (P = 0.006).

LIMITATION

It is unclear whether arterial fibrosis of the brachial artery evaluated by using CAVI is applicable for arteriosclerosis of other arterial districts, and clinical outcomes were not evaluated in this study.

CONCLUSION

CAVI reflects the histological arterial fibrosis of hemodialysis patients and is a useful clinical marker for evaluating arterial stiffness in these patients.

Relationships Between Vascular Indexes and Atherosclerotic Risk Factors in Patients With Type 2 Diabetes Mellitus

The relationships of cardio-ankle vascular index, (a new indicator of arterial stiffness), common carotid artery intima-media thickness, and ankle-brachial pressure index with atherosclerotic risk factors were compared in patients with type 2 diabetes. There were significant correlations between each pair of the above vascular indexes. Both cardio-ankle vascular index and intima-media thickness showed significant correlations with age, systolic blood pressure, pulse pressure, and serum total cholesterol. Ankle-brachial pressure index showed a significant negative correlation with pulse pressure but not with systolic blood pressure and total cholesterol. Logistic regression analysis showed that cardio-ankle vascular index and intima-media thickness were associated with systolic blood pressure and pulse pressure independently of age. These results suggest that there are significant associations among the 3 vascular indexes and that systolic blood pressure and pulse pressure are major, age-independent determinants of cardio-ankle vascular index and common carotid artery intima-media thickness in patients with diabetes.

Availability of cardio-ankle vascular index (CAVI) as a screening tool for atherosclerosis

BACKGROUND

A novel index, the cardio-ankle vascular index (CAVI), which reflects the stiffness of the aorta, femoral artery, and tibial artery, was recently developed by measuring brachial - ankle pulse wave velocity and blood pressure.

METHODS AND RESULTS

In the present study 1,014 Japanese adults from the general population were screened to clarify the correlation between CAVI and other existing markers related to atherosclerosis, including carotid intima - media thickness (CIMT) and homocysteine (HCY). CAVI was strongly associated with age in both men and women. After adjustment for age and sex, CAVI was correlated with systolic and diastolic blood pressures. In addition, CAVI was significantly correlated with total cholesterol hemoglobin A(1c) and total HCY, as well as CIMT.

CONCLUSION

CAVI is an appropriate screening tool for atherosclerosis, but further studies are needed to establish a convenient and effective screening system using it.

Cardio-ankle vascular index measures arterial wall stiffness independent of blood pressure

Although brachial-ankle pulse wave velocity (baPWV) is a non-invasive method of detecting arteriosclerosis, it is affected by changes in blood pressure (BP). Cardio-ankle vascular index (CAVI) is a new method for estimating arteriosclerosis, and it has been reported to be less influenced by BP. We investigated the influence of BP changes on CAVI and the correlation of CAVI to clinical factors and carotid arteriosclerosis. CAVI and baPWV in 35 non-diabetic and 33 diabetic subjects were measured in increased BP (after stair climbing) and rested BP (after 10min of rest). Intima-media thickness (IMT) of carotid arteries was measured by ultrasoundsonography. We achieved the following results: CAVI did not show a significant change with a change in BP in both non-diabetic and diabetic subjects. On the contrary, baPWV was significantly influenced by BP changes. Carotid artery IMT had a significant positive correlation with CAVI and baPWV. Multiple regression analysis revealed that significant risk factors of high baPWV were age and systolic BP. On the contrary, significant risk factors of high CAVI were age and hemoglobin A1c, while systolic BP was not relevant. Our findings suggest that CAVI is independent of BP and useful as an indicator of early arteriosclerosis in diabetic subjects.

Prospective assessment of lower-extremity peripheral arterial disease in diabetic patients using a novel automated optical device

A new optical device based on the photoplethysmograph (PPG) method and an innovative algorithm for the assessment of lower-extremity peripheral arterial disease was investigated prospectively in patients with type II diabetes. This new functional PPG (fPPG) technique uses a cuffless functional test to assess diabetic peripheral arterial disease without operator dependency and the incompressible arteries, issues associated with ankle brachial pressure index (ABPI) measurement. Diabetic patients (n = 24; 47 legs; age, 70 +/- 3 years) were recruited from the vascular clinic, and controls (n = 15; 30 legs; age, 66 +/- 5 years) were recruited from the orthopedic outpatient clinic. All underwent resting ABPI, fPPG, and duplex angiography (DA) as "gold standard." fPPG requires the placement of an optical probe on the toe for acquisition of pulsatile arterial perfusion for a period of 30 seconds with the leg in supine and raised at 45 degrees positions. The data were analyzed, and indices were generated by an automated computer system. In those with diabetes, fPPG correlated significantly with DA (r = -.68, P < .01) and ABPI (r = -.65, P < .01). We also found a significant correlation between ABPI and DA (r = .81, P < .01). The analysis of the receiver operator curve showed that optimum sensitivity and specificity for ABPI and fPPG were 80% and 93% and 83% and 71%, respectively, against DA. This method uses changes in pulsatile arterial blood volume using a simple cuffless functional test. The fPPG investigation period was much shorter (5 minutes) with independence of operator skills, whereas ABPI took longer (10-15 minutes) and required operator experience. Although the fPPG results are promising, further improvement (eg, by incorporation of functional skin color and temperature changes) is required to improve the sensitivity and specificity of the system.

The relationship between the acute changes of the systolic blood pressure and the brachial-ankle pulse wave velocity

BACKGROUND

The brachial-ankle pulse wave velocity (baPWV) is a useful parameter to assess arterial stiffness. However, it is difficult to evaluate arterial stiffness in hypertensive patients because the baPWV is affected by the blood pressure itself. This study was designed to estimate the relationship between the change of the blood pressure parameters and the baPWV (deltabaPWV) when hypertensive patients were subjected to an acute reduction of blood pressure.

METHODS

Thirty patients with essential hypertension and whose blood pressure was higher than 140/90 mmHg were enrolled. In all the patients, the blood pressure and baPWV were measured using an automatic waveform analyzer with the patients at a resting state. When the reduction of blood pressure was more than 10 mmHg after sublingual administration of nifedipine 10 mg, then the blood pressure and baPWV were measured again in the same manner and then they were compared with the baseline values. Spearman's correlation and multiple linear regression tests were performed to estimate the relationship between the change of the blood pressure parameters (deltaSBP, deltaDBP, deltaMAP and deltaPP) and the deltabaPWV.

RESULTS

The baPWV was significantly decreased shortly after the administration of nifedipine (1903.6+/-305.2 cm/sec vs. 1716+/-252.0 cm/sec, respectively, p<0.01). The deltabaPWV was correlated with the deltaSBP (r=0.550, p<0.01), deltaDBP (r=0.386, p<0.05), deltaMAP (r=0.441, p<0.05), and deltaPP (r=0.442. p<0.05). On the multiple regression analysis, the deltaSBP was the only significant variable for predicting the deltabaPWV, and the linear equation was deltabaPWV=8.7xSBP-48.

CONCLUSIONS

The baPWV is affected by the systolic blood pressure level to a large degree and careful attention must be paid to the blood pressure level when evaluating arterial stiffness with using the baPWV.

Effects of IL-6, adiponectin, CRP and metabolic syndrome on subclinical atherosclerosis

BACKGROUND

Inflammation has been implicated in the pathogenesis of cardiovascular disease. Since there have been few studies elucidating gender-specific effect of inflammation and metabolic syndrome (MetS) on subclinical atherosclerosis, we evaluated the relative contribution of these factors in healthy subjects.

METHODS

MetS components, carotid intima-media thickness (IMT) and pulse wave velocity (PWV) were evaluated in apparently healthy 714 men and 364 women (40-59 y). Serum levels of high sensitive C-reactive protein (hs-CRP), interleukin-6 (IL-6) and adiponectin were also examined.

RESULTS

Increase in number of clustering MetS components was more clearly associated with worsening of IMT and PWV in women than in men. Serum IL-6 level was positively correlated with IMT and PWV, and adiponectin level was negatively correlated with IMT in men but not in women. The subjects either with a "high" IL-6 or hs-CRP, or a "low" adiponectin were associated with increase in IMT in the presence of MetS, though there was no significant effect of MetS in those with low inflammation.

CONCLUSIONS

While IL-6 and adiponectin are the important risk factors for early arterial alterations in men, components of MetS present profound effects on subclinical atherosclerosis in women rather than in men.

Relationship between cardio-ankle vascular index (CAVI) and carotid atherosclerosis in patients with essential hypertension

Aortic stiffness measured by aorta-iliac or carotid-femoral pulse wave velocity (PWV) predicts all-cause and cardiovascular mortality. Brachial-ankle PWV (baPWV) has been developed as a more convenient assessment of arterial stiffness. However, the problem with clinical use of baPWV is that the index itself is closely dependent on blood pressure. Recently, a new method, termed the cardio-ankle vascular index (CAVI), has been proposed in Japan to overcome the disadvantages associated with measuring PWV. However, its clinical usefulness has not yet been fully clarified. In the present study, we compared the usefulness of CAVI with that of ultrasound for evaluating atherosclerosis in patients with essential hypertension. CAVI was measured in 70 hypertensive patients. The intima-media thickness (IMT), cross-sectional distensibility coefficient (CSDC), stiffness parameter beta, and mean diastolic (V(d)) and systolic (V(s)) flow velocities were evaluated by carotid ultrasound. The V(d)/V(s) ratio, an index of peripheral arterial resistance, was also calculated. CAVI was positively correlated with IMT (r=0.360, p=0.0022) and stiffness beta (r=0.270, p=0.0239) and negatively correlated with V(d)/V(s) (r=-0.471, p<0.0001) and CSDC (r=-0.315, p=0.0079). Stepwise regression analysis revealed that age (r=0.475, p<0.0001) and pulse pressure (r=0.492, r<0.0001) were independent determinants of CAVI. These results suggest that CAVI is a useful clinical marker for evaluating atherosclerosis and arteriolosclerosis in patients with essential hypertension.

Evaluation of cardiovascular risk factors and related clinical markers in healthy young Japanese adults

BACKGROUND

Since atherosclerosis is a slowly progressive process at a young age, effective preventive measures should be taken early in life to prevent future events associated with cardiovascular disease.

METHODS

The study population comprised 132 young Japanese adults (mean age 21.4 years, range 18-31 years). We screened plasma total homocysteine and serum folate levels and evaluated mean carotid intima-media thickness and cardio-ankle vascular index.

RESULTS

Multiple regression analysis after adjustment for age and sex revealed that only folate levels were significantly correlated with plasma total homocysteine levels (beta=-0.37, p=0.028). Carotid intima-media thickness adjusted for age and sex and compared between quintiles of total homocysteine levels was significantly increased in the highest quintile compared with other quintiles. Cardio-ankle vascular index increased with age in both women and men, but no additional determinants were identified in young adults.

CONCLUSION

Serum folate is an independent determinant of plasma total homocysteine levels, and mild hyperhomocysteinemia may represent a risk factor for increased carotid intima-media thickness, even in young adults. Comprehensive health education from the early period of life, including the suggestion of appropriate dietary measures, is important for effective prevention of future atherosclerosis.

Clinical significance and reproducibility of new arterial distensibility index

BACKGROUND

The brachial-ankle pulse wave velocity (baPWV) is used to evaluate the degree of atherosclerosis and arterial distensibility, but its major limitation is that it is affected by changes in blood pressure (BP) during measurement. Recently, a new atherosclerotic index, the cardio-ankle vascular index (CAVI), has been developed by measuring PWV and BP. CAVI is adjusted for BP based on the stiffness parameter beta and should measure arterial stiffness independent of BP. The purpose of this study was to evaluate the validity of CAVI compared with baPWV, the reproducibility of the measurement of CAVI, and the effect of BP changes on CAVI and baPWV.

METHODS AND RESULTS

One thousand and thirty-three consecutive subjects undergoing health checkups were studied. CAVI was automatically calculated from the pulse volume record, BP, and the vascular length from heart to ankle. In this general population, both baPWV and CAVI demonstrated a positive correlation with age and systolic BP (SBP). CAVI showed a weaker correlation with SBP than baPWV. The measurement of CAVI demonstrated good reproducibility and was not affected by the increase in BP during measurement.

CONCLUSIONS

CAVI is a useful index of arterial distensibility and is not influenced by BP changes during measurement.