Relation Between Renal Function Within the Normal Range and Central and Peripheral Arterial Stiffness in Hypertension

Causal Association of Arterial Stiffness With the Risk of Chronic Kidney Disease

Background

Previous studies on the direction of the association between arterial stiffness (AS) and chronic kidney disease (CKD) were inconsistent, leaving a knowledge gap in understanding the temporal sequence of the association.

Objectives

This study sought to assess the temporal and longitudinal relationship between AS and CKD.

Methods

The temporal relationship between AS measured by brachial ankle pulse wave velocity and CKD measured by estimated glomerular filtration rate (eGFR) was analyzed among 7,753 participants with repeated examinations in the Kailuan study using cross-lagged panel analysis. The longitudinal associations of AS status and vascular aging (VA) phenotype with incident CKD were analyzed among 10,535 participants.

Results

The adjusted cross-lagged path coefficient (β 1 = -0.03; 95% CI: -0.06 to -0.01; P < 0.0001) from baseline brachial ankle pulse wave velocity to follow-up eGFR was significantly greater than the path coefficient (β 2 = -0.01; 95% CI: -0.02 to 0.01; P = 0.6202) from baseline eGFR to follow-up brachial ankle pulse wave velocity (P < 0.0001 for the difference). During a median follow-up of 8.48 years, 953 cases of incident CKD (9.05%) occurred. After adjustment for confounders, borderline (HR: 1.17; 95% CI: 1.08-1.38) and elevated AS (HR: 1.39; 95% CI: 1.12-1.72) was associated a higher risk of CKD, compared with normal AS. Consistently, supernormal VA (HR: 0.76; 95% CI: 0.66-0.86) was associated with a decreased and early VA (HR: 1.36; 95% CI: 1.29-1.43) was associated with an increased risk of CKD, compared with normal VA.

Conclusions

AS appeared to precede the decrease in eGFR. Additionally, increased AS and early VA were associated with an increased risk of incident CKD.

Glycemia is associated with subclinical atherosclerosis through renal function in nondiabetic apparently healthy adults: a mediation analysis

The causative associations between glycemia and early alterations in renal and vascular function remain unclear. To examine the interplay among glycemia, renal function, and markers of subclinical atherosclerosis in apparently healthy subjects. Nondiabetic (30-60 years old) individuals (n = 205) without chronic kidney disease or cardiovascular disease were consecutively recruited from a cardiovascular prevention clinic. All subjects underwent arterial stiffness assessment by measuring the carotid-femoral pulse wave velocity (cfPWV). Glomerular filtration rate (GFR) was estimated by CKD-EPI equation. Study procedures were identical in the two visits (median follow-up 66 months). We employed structural equation modeling (SEM) analysis to investigate the directionality of associations. Baseline fasting plasma glucose (FPG) was independently and inversely associated with GFR (p = 0.008). GFR was significantly associated with cfPWV (p < 0.001) at baseline. By SEM analysis decreasing baseline GFR directly correlated with increasing cfPWV (p = 0.003) whereas FPG correlated with cfPWV indirectly through GFR (mediation) (P = 0.032). FPG did not mediate the effect of GFR on cfPWV (P = 0.768). SEM analysis of longitudinal data revealed bidirectional correlations between changes in FPG and GFR (P < 0.001). Alterations in GFR were directly related to changes in cfPWV (p < 0.001) whereas FPG only indirectly correlated with cfPWV through GFR changes (P = 0.002). In apparently healthy nondiabetic subjects, the association between baseline or longitudinal glycemia levels and arterial stiffening was indirect, consistently mediated by renal function status. These findings provide the first clinical evidence supporting the directionality between kidney function and glycemia in nondiabetic subjects leading to vascular dysfunction. In apparently healthy nondiabetic subjects, without cardiovascular disease or chronic kidney disease, the association between baseline or longitudinal glycemia levels and arterial stiffening was indirect, consistently mediated by renal function status.

The Analysis of Arterial Stiffness in Heart Failure Patients: The Prognostic Role of Pulse Wave Velocity, Augmentation Index and Stiffness Index

Background: The role of arterial stiffness in the pathogenesis and clinical outcome of heart failure (HF) patients has to be clarified. The aim of this study was to evaluate the prognostic role of arterial stiffness in HF patients discharged after acute episode of decompensation by evaluating cut-off values for clinical assessment. Methods: Patients admitted for decompensated heart failure (ADHF) underwent pre-discharge evaluation. Arterial stiffness was measured by aortic pulse wave velocity (aPWV), augmentation index (AIx75) and stiffness index (β0). Patients were also evaluated after discharge for a variable follow-up time. Results: We observed 199 patients (male 61.3%, age 76.2 ± 10.7 years) after discharge for a median of 437 days (IQR 247-903), 69 (34.7%) patients suffered HF with preserved ejection fraction (HFpEF), 45 (22.6%) patients experienced HF with mid-range ejection fraction (HFmEF) and 85 (42.7%) reported an HF with reduced ejection fraction (HFrEF). After the adjustment for principal confounders, aPWV, AIx75 and β0 were inversely correlated with free-event survival (p = 0.006, p < 0.001, p = 0.001): only β0 was inversely correlated with overall survival (p = 0.03). Analysing the threshold, overall survival was inversely correlated with β0 ≥3 (HR 2.1, p = 0.04) and free-event survival was inversely correlated with aPWV ≥10 m/s (HR 1.7, p = 0.03), AIx75 ≥ 25 (HR 2.4, p < 0.001), and β0 ≥ 3 (HR 2.0, p = 0.009). Dividing HF patients for LV ejection fraction, β0 and AIx75 appeared to be accurate prognostic predictors among the three different classes according to free-event survival. Conclusions: The non-invasive measurements of arterial stiffness proved to be strong prognostic parameters in HF patients discharged after an acute HF decompensation.

Comprehensive assessment of systemic arteriosclerosis in relation to the ocular resistive index in acute coronary syndrome patients

This study aimed to investigate the relationship between ocular vascular resistance parameters, evaluated by laser speckle flowgraphy (LSFG), and systemic atherosclerosis, renal parameters and cardiac function in acute coronary syndrome (ACS) patients. We evaluated 53 ACS patients between April 2019 and September 2020. LSFG measured the mean blur rate (MBR) and ocular blowout time (BOT) and resistivity index (RI). 110 consequent patients without a history of coronary artery disease who visited ophthalmology as a control group. Significant positive correlations were observed between ocular RI and systemic parameters in ACS patients, including intima-media thickness (r = 0.34, P = 0.015), brachial-ankle pulse-wave velocity (r = 0.41, P = 0.002), cystatin C (r = 0.32, P = 0.020), and E/e’ (r = 0.34, P = 0.013). Ocular RI was significantly higher in the ACS group than in the control group in male in their 40 s (0.37 ± 0.02 vs. 0.29 ± 0.01, P < 0.001) and 50 s (0.36 ± 0.02 vs. 0.30 ± 0.01, P = 0.01). We found that the ocular RI was associated with systemic atherosclerosis, early renal dysfunction, and diastolic cardiac dysfunction in ACS patients, suggesting that it could be a useful non-invasive comprehensive arteriosclerotic marker.

Risk for subsequent hypertension and cardiovascular disease after living kidney donation: is it clinically relevant?

The first successful live donor kidney transplant was performed in 1954. Receiving a kidney transplant from a live kidney donor remains the best option for increasing both life expectancy and quality of life in patients with end-stage kidney disease. However, ever since 1954, there have been multiple questions raised on the ethics of live kidney donation in terms of negative impacts on donor life expectancy. Given the close relationship between reduced kidney function in patients with chronic kidney disease (CKD) and hypertension, cardiovascular disease and cardiovascular mortality, information on the impact of kidney donation on these is particularly relevant. In this article, we review the existing evidence, focusing on the more recent studies on the impact of kidney donation on all-cause mortality, cardiovascular mortality, cardiovascular disease and hypertension, as well as markers of cardiovascular damage including arterial stiffness and uraemic cardiomyopathy. We also discuss the similarities and differences between the pathological reduction in renal function that occurs in CKD, and the reduction in renal function that occurs because of a donor nephrectomy. Kidney donors perform an altruistic act that benefits individual patients as well as the wider society. They deserve to have high-quality evidence on which to make informed decisions.

Longitudinal Study of Brachial-Ankle Pulse Wave Velocity and Change in Estimated Glomerular Filtration Rate among Chinese Adults

BACKGROUND AND OBJECTIVES

Studies on the association between arterial stiffness and kidney function have generated inconsistent results. Whether arterial stiffness is linked to decline in renal function warrants further study. This study aimed to investigate the association between brachial-ankle pulse wave velocity (baPWV) and longitudinal change in estimated glomerular filtration rate (eGFR) among Chinese adults.

METHODS

In this longitudinal study, 8,264 participants in a community-based cohort had baPWV measured in 2010-2011 and were followed in subsequent surveys through to 2016. During each survey visit, fasting blood samples were collected for serum creatinine and eGFR was calculated. Participants were divided into 5 groups (Q1-Q5) by baPWV quintile. The association between baPWV and longitudinal changes in eGFR was assessed using generalized estimating equation models.

RESULTS

A total of 8,045 participants were included in the final analysis. The average age was 54 ± 12 years (age range 24-97 years), and mean eGFR was 93.0 ± 18.6 mL/min/1.73 m2. There was an inverse linear association between baseline baPWV and eGFR change rate (p < 0.001). Compared with Q1 (lowest) group, the mean differences and 95% CI in eGFR decrease rate among Q2-Q5 groups were -0.23 (-0.62, 0.16), -0.67 (-1.06, -0.28), -1.11 (-1.50, -0.72), and -1.30 (-1.69, -0.92) mL/min/1.73 m2 per year, respectively, after adjustment for age, gender, and other potential confounders (p trend < 0.0001). For each 100 cm/s increase in baPWV at baseline, the fully adjusted mean difference in eGFR decrease rate was -0.14 mL/min/1.73 m2 per year (95% CI -0.18, -0.10; p < 0.0001). Compared with participants with baPWV < 1,400 cm/s, the fully adjusted mean difference in eGFR decrease rate was -0.92 mL/min/1.73 m2 per year (95% CI -1.18, -0.66) for those with baPWV ≥ 1,400 cm/s (p < 0.0001).

CONCLUSIONS

Participants with a higher baPWV at baseline had a greater decrease in eGFR over time. Future studies could examine the relationship between baPWV and decline in renal function in higher risk cohorts, and its potential role in targeting reno-protective interventions to those who may benefit from them most.

Impact of Cardiovascular Hemodynamics on Cognitive Aging

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Pulse wave velocity is a new predictor of acute kidney injury development after off-pump coronary artery bypass grafting

Background

Brachial-ankle pulse wave velocity (baPWV) is the simple, non-invasive, gold-standard method for assessing arterial stiffness. However, baPWV has been shown to be associated with renal dyfunction, with a few reports demonstrating an association between baPWV and postoperative acute kidney injury (AKI) among surgical patients.

Methods

We retrospectively analyzed preoperative baPWV data that were prospectively collected from 164 patients who underwent off-pump coronary artery bypass grafting (CABG) between April 2013 and July 2019 (mean age: 66.2 ± 10.3 years, 29.3% females). Primarily, baPWV was investigated as an independent predictor of postoperative AKI development; secondarily, the patients were divided into high and low PWV groups according to the optimal baPWV cut-off value. Postoperative complications, mortality, and mid-term survival were compared between the two groups.

Results

AKI developed in 30 patients (18.3%). Univariate analysis showed that AKI was significantly associated with baPWV (20.2±7.3 vs. 16.2±2.8 m/s, p < 0.001), age, preoperative serum creatinine, and EuroSCORE. Multivariable logistic regression analysis revealed baPWV as independently associated with postoperative AKI even after adjustment for preoperative creatinine, old age (> 75 years), hypertension, diabetes under insulin therapy, and EuroSCORE. Moreover, area under the curve (AUC) analysis indicated that PWV can predict AKI better than preoperative creatinine levels (AUC, 0.781 [95% confidence interval, 0.688–0.874] vs. 0.680 [0.568–0.792]). The group-dividing baPWV cut-off value for AKI was 19 m/s. There were no 30-day mortality. The in-hospital mortality rates in the high and the low PWV groups were 2.2% (n = 1) and 0.8% (n = 1), respectively (p = 0.484). Midterm survival rates were not different between the two groups, but the rate of composite neurologic complication composed of stroke and delirium, was higher, and rate of mechanical ventilatory support was longer, in the high PWV group.

Conclusion

Brachial-ankle pulse wave velocity was an independent predictor of postoperative AKI following off-pump CABG, and high baPWVs may affect the composite neurologic outcome and the duration of mechanical ventilatory support.

The predictive value of β2-MG and TGF-β for elderly hypertensive nephropathy

Predictive value of β2-microglobulin (β2-MG) and transforming growth factor-β (TGF-β) for elderly hypertensive nephropathy was investigated. The clinical data of 56 patients with hypertensive nephropathy and admitted to Affiliated Hospital of Chengde Medical College from December 2015 to December 2017, were retrospectively analyzed and the clinical data were used as the study group, the clinical data of 50 patients with hypertension, but not nephropathy, were selected as the control group. The expression levels of β2-MG and TGF-β in the serum were detected by ELISA. The correlation between β2-MG and TGF-β was analyzed by Pearson's correlation. The sensitivity and specificity of β2-MG, TGF-β and combined application in the diagnosis of hypertensive nephropathy were analyzed by ROC curve. The expression levels of β2-MG and TGF-β in the serum of the patients in the study group were significantly higher than those in the control group (P<0.001). There was a positive correlation between the expression levels of β2-MG and TGF-β in the serum of the patients in the study group (r=0.619, P<0.001). The AUC of β2-MG in the diagnosis of hypertensive nephropathy was 0.786. The AUC of TGF-β in the diagnosis of hypertensive nephropathy was 0.793. The AUC of the combined application of β2-MG and TGF-β in the diagnosis of hypertensive nephropathy was 0.860. β2-MG and TGF-β were highly expressed in the patients with hypertensive nephropathy, and the expression levels of β2-MG and TGF-β were positively correlated (r=0.619, P<0.001). The combined application of β2-MG and TGF-β in the diagnosis of hypertensive nephropathy could reduce or even avoid the missed diagnosis caused by single detection. The two indicators complemented and confirmed each other, which had a great significance for improving the positive diagnosis rate of hypertensive nephropathy.

Determining Factors of Arterial Stiffness in Subjects with Metabolic Syndrome

BACKGROUND

Metabolic syndrome (MS) is a clustering entity characterized by obesity, hypertension, hyperglycemia, dyslipidemia, and insulin resistance. Early detection of atherosclerosis is important in patients with MS because cardiovascular diseases are the main cause of mortality in these patients.

METHODS

We aimed to investigate the factors influencing arterial stiffness, pulse wave velocity, and the augmentation index, respectively, in 150 subjects with MS (94 women and 56 men; mean age 60.56 ± 9.8 years). Arterial stiffness was measured using the TensioMed™ Arteriograph. We tested the relationship between arterial parameters and insulin resistance measured by the determination of insulinemia (the ELISA method) and the homeostasis model assessment index (HOMA).

RESULTS

In multivariate analysis we identified the independent factors that influence arterial stiffness: systolic blood pressure (coefficient of determination 3.586; P < 0.0001), serum triglycerides (coefficient of determination 3.579; P < 0.0001), and age (coefficient of determination 3.510; P = 0.001) are independent predictive factors for pulse wave velocity. The independent predictive factors of the augmentation index were the body mass index (coefficient of determination 0.55; P = 0.009), the presence of diabetes mellitus (coefficient of determination 4.7; P = 0.03), mean arterial pressure (coefficient of determination 0.44; P < 0.0001), gender (coefficient of determination 9.2; P < 0.0001), age (coefficient of determination 0.3; P < 0.0001), and heart rate (coefficient of determination 0.66; P < 0.0001). Insulin resistance (HOMA index) was a predictor of the brachial augmentation index (β coefficient 3.4; P < 0.001) and was not a predictor of pulse wave velocity (β = -0.3; P = 0.6) in our study.

CONCLUSIONS

Given the known predictive value of pulse wave velocity for cardiovascular events, identifying the factors responsible for the increase in arterial stiffness is extremely important.

Associations Between Kidney Disease Measures and Regional Pulse Wave Velocity in a Large Community-Based Cohort: The Atherosclerosis Risk in Communities (ARIC) Study

RATIONALE & OBJECTIVE

Arterial stiffness is suggested as a mediator of cardiorenal interaction. However, previous studies reported inconsistent associations between chronic kidney disease (CKD) and arterial stiffness and were limited by using either estimated glomerular filtration rate (eGFR) or albumin-creatinine ratio (ACR) and examining arterial stiffness at limited segments.

STUDY DESIGN

Cross-sectional.

SETTING & PARTICIPANTS

3,424 Atherosclerosis in Communities (ARIC) Study participants aged 66 to 90 years during 2011 to 2013.

PREDICTORS

eGFR and ACR.

OUTCOME

Pulse wave velocity (PWV) at 6 segments: carotid-femoral (cfPWV), heart-carotid (hcPWV), and heart-femoral (hfPWV), reflecting central stiffness; heart-ankle (haPWV) and brachial-ankle (baPWV), representing both central and peripheral stiffness; and femoral-ankle (faPWV), indicating peripheral stiffness.

ANALYTICAL APPROACH

Multiple linear and logistic regression models to quantify the associations of eGFR and ACR with continuous PWV and elevated PWV (in the highest quartile), respectively.

RESULTS

After adjusting for age, sex, and race, higher cfPWV and hfPWV were consistently associated with lower eGFR and higher ACR. Higher haPWV and baPWV were also observed with higher ACR. The independent association of both CKD measures with elevated cfPWV remained consistent after adjusting for additional confounders (ORs of elevated cfPWV were 1.09 [95% CI, 1.01-1.18] per 15-mL/min/1.73m² lower eGFR and 1.20 [95% CI, 1.07-1.33] per 4-fold higher ACR). Higher ACR was also associated with elevated hfPWV and haPWV (ORs per 4-fold higher ACR were 1.25 [95% CI, 1.12-1.39] for elevated hfPWV and 1.19 [95% CI, 1.06-1.33] for elevated haPWV). Lower eGFR was associated with lower odds of elevated baPWV and faPWV (ORs per 15-mL/min/1.73m² lower eGFR were 0.92 [95% CI, 0.84-0.99] and 0.91 [95% CI, 0.85-0.99], respectively).

LIMITATION

Unable to address temporality between CKD measures and arterial stiffness.

CONCLUSIONS

Both lower eGFR and higher ACR are independently associated with measures of central arterial stiffness, with stronger associations for ACR over eGFR. Our findings suggest that central arterial stiffness may be an important pathophysiologic phenotype of vascular disease in CKD.

Volume status and arterial blood pressures are associated with arterial stiffness in hemodialysis patients

BACKGROUND

Arterial stiffness is a strong predictor of mortality in hemodialysis patients. In this study, we aimed to investigate possible relations of arterial stiffness with volume status determined by bioimpedance analysis and aortic blood pressure parameters. Also, effects of a single hemodialysis session on these parameters were studied.

METHODS

A total of 75 hemodialysis patients (M/F: 43/32; mean age: 53 ± 17) were enrolled. Carotid-femoral pulse wave velocity, augmentation index, and aortic pulse pressure were measured by applanation tonometry before and after hemodialysis. Extracellular fluid and total body fluid volumes were determined by bioimpedance analysis.

RESULTS

Carotid-femoral pulse wave velocity (9.30 ± 3.30 vs 7.59 ± 2.66 m/s, p < 0.001), augmentation index (24.52 ± 9.42 vs 20.28 ± 10.19, p < 0.001), and aortic pulse pressure (38 ± 14 vs 29 ± 8 mmHg, p < 0.001) significantly decreased after hemodialysis. Pre-dialysis carotid-femoral pulse wave velocity was associated with age (r² = 0.15, p = 0.01), total cholesterol (r² = 0.06, p = 0.02), peripheral mean blood pressure (r² = 0.10, p = 0.005), aortic-mean blood pressure (r² = 0.06, p = 0.02), aortic pulse pressure (r² = 0.14, p = 0.001), and extracellular fluid/total body fluid (r² = 0.30, p < 0.0001). Pre-dialysis augmentation index was associated with total cholesterol (r² = 0.06, p = 0,02), aortic-mean blood pressure (r² = 0.16, p < 0.001), and aortic pulse pressure (r² = 0.22, p < 0.001). Δcarotid-femoral pulse wave velocity was associated with Δaortic-mean blood pressure (r² = 0.06, p = 0.02) and inversely correlated with baseline carotid-femoral pulse wave velocity (r² = 0.29, p < 0.001). Pre-dialysis Δaugmentation index was significantly associated with Δaortic-mean blood pressure (r² = 0.09, p = 0.009) and Δaortic pulse pressure (r² = 0.06, p = 0.03) and inversely associated with baseline augmentation index (r² = 0.14, p = 0.001). In multiple linear regression analysis (adjusted R² = 0.46, p < 0.001) to determine the factors predicting Log carotid-femoral pulse wave velocity, extracellular fluid/total body fluid and peripheral mean blood pressure significantly predicted Log carotid-femoral pulse wave velocity (p = 0.001 and p = 0.006, respectively).

CONCLUSION

Carotid-femoral pulse wave velocity, augmentation index, and aortic pulse pressure significantly decreased after hemodialysis. Arterial stiffness was associated with both peripheral and aortic blood pressure. Furthermore, reduction in arterial stiffness parameters was related to reduction in aortic blood pressure. Pre-dialysis carotid-femoral pulse wave velocity was associated with volume status determined by bioimpedance analysis. Volume control may improve not only the aortic blood pressure measurements but also arterial stiffness in hemodialysis patients.

Vascular dysfunction in children and young adults with autosomal dominant polycystic kidney disease

Background

Adults with autosomal dominant polycystic kidney disease (ADPKD) exhibit vascular dysfunction, as evidenced by impaired endothelium-dependent dilation (EDD) and stiffening of the large elastic arteries. However, it is unknown whether vascular dysfunction begins earlier in the course of ADPKD. The aim of the study was to assess EDD and arterial stiffness in children and young adults with ADPKD.

Methods

Fifteen children and young adults 6–22 years of age with ADPKD and normal renal function were prospectively recruited for participation in a cross-sectional study. Fifteen healthy controls were enrolled to match cases for age and sex. The primary outcomes were EDD, measured as brachial artery flow-mediated dilation (FMDBA), and arterial stiffness, measured as carotid-femoral pulse wave velocity (CFPWV).

Results

ADPKD cases were more likely to be taking an angiotensin-converting enzyme inhibitor, but otherwise did not differ from controls in clinical characteristics, including blood pressure. FMDBA was 25% lower in children and young adults with ADPKD (7.7 ± 0.9%, mean ± SE) when compared with matched controls (10.2 ± 0.8%) (P < 0.05). CFPWV was 14% higher in children and young adults with ADPKD (544 ± 23 cm/s) when compared with matched controls (478 ± 17 cm/s) (P < 0.05). Secondary measures of arterial stiffness, carotid augmentation index and carotid systolic blood pressure were also increased in cases when compared with controls (P < 0.05).

Conclusions

Impaired EDD and increased arterial stiffness, important independent predictors of future cardiovascular events and mortality, are evident very early in the course of ADPKD in the presence of normal kidney function. Novel interventions to reduce vascular dysfunction in children and young adults with ADPKD should be evaluated, as childhood and young adulthood may represent a critical therapeutic window to reduce future cardiovascular risk in patients with ADPKD.

Aortic-to-brachial stiffness gradient and kidney function in type 2 diabetes

OBJECTIVES

A reversed aortic-to-brachial stiffness gradient (ab-SG), defined as aortic pulse wave velocity (aPWV) greater than brachial PWV (bPWV), was recently shown to predict mortality independent of aPWV in dialysis patients. Patients with type 2 diabetes mellitus (T2DM) have increased risk of renal damage and exhibit haemodynamic abnormalities at rest and during exercise that may alter the ab-SG. This study aimed to examine ab-SG in patients with T2DM by comparison with nondiabetic controls during rest and exercise, and to determine associations between ab-SG, aPWV, and kidney function.

METHODS

Study participants were 60 patients with T2DM and 60 age and sex-matched nondiabetic controls (58 ± 8 years, 55% male both). ab-SG was defined as the quotient of bPWV (carotid-to-radial) and aPWV (carotid-to-femoral) recorded via applanation tonometry. Kidney function was assessed using estimated glomerular filtration rate (eGFR). The exercise substudy was undertaken in 21 patients with T2DM and 21 matched nondiabetic controls during semirecumbent exercise.

RESULTS

ab-SG was significantly lower in patients with T2DM (0.99 ± 0.2 vs. 1.2 ± 0.3, P < 0.001) and aPWV, but not bPWV, was significantly higher (P < 0.001 and P = 0.25). A total of 58% of patients with T2DM vs. 27% of nondiabetic controls (χ = 11.0, P < 0.001) had a reversed ab-SG (aPWV ≥ bPWV). ab-SG predicted eGFR independent of age, sex, T2DM status, and cardiovascular risk factors (β = 13.2, P = 0.024), whereas aPWV did not (β = -0.88, P = 0.30). Exercise ab-SG was significantly lower in patients with T2DM (0.97 ± 0.2 vs. 1.2 ± 0.2, P < 0.001), but did not predict eGFR.

CONCLUSIONS

Patients with T2DM have a reversed ab-SG during rest and exercise. Resting ab-SG predicts kidney function independent of aPWV, implying a reversed ab-SG may have a pathophysiological function.

Predictors of aortic pulse wave velocity in the elderly with severe aortic stenosis

Predictors of aortic pulse wave velocity (AoPWV) were not previously studied in the elderly with severe aortic stenosis (AS). We aimed to compare the AoPWV in these patients with matched controls and to study the predictors of AoPWV in this population. We measured the AoPWV during cardiac catheterisation in 40 patients with severe AS and 20 matched controls. AoPWV in both groups was similar (p = 0.198) and lied within normal reference value for age in 68 % of elderly with severe AS. Central systolic blood pressure (SBP) (adjusted β = 0.45, p = 0.001) and glomerular filtration rate (GFR) (adjusted β = -0.29, p = 0.023) were the only independent predictors of AoPWV in AS group. Central SBP >140 mmHg was the best predictor of abnormal AoPWV (≥14.6 m/s) with 100 % sensitivity and 70 % specificity, p < 0.001.

CONCLUSION

AoPWV is not increased in the elderly with severe AS compared to controls, and lies within the reference value for age in the majority of these patients. Central SBP >140 mmHg best predicts abnormal AoPWV in the elderly with severe AS.

Association between central aortic pulsatility and glomerular filtration rate in patients with coronary artery disease

Objective:

Aortic stiffness and chronic kidney disease share common risk factors. Increased aortic stiffness is a predictor of lower estimated glomerular filtration rate (eGFR) at lower levels of renal functions. We aimed to investigate the association between invasively measured central aortic pulsatility (AP) as an indicator of aortic stiffness and eGFR in a population with coronary artery disease and without overt renal disease.

Methods:

This study had a cross-sectional design. Data were retrospectively collected. We evaluated 72 patients (44 males and 28 females; mean age 59.0±10.3 years) with coronary artery disease. eGFR was calculated with dividing the Cockcroft–Gault formula by body surface area. Direct measurements of aortic blood pressures were utilized to calculate pulse pressure and AP. Multiple linear regression analysis was performed to test the relationship between eGFR and AP, independent from potential confounders.

Results:

eGFR was significantly correlated with age (r=0.489, p<0.001), body surface area (r=0.324, p=0.006), weight (r=0.323, p=0.006), aortic pulse pressure (r=-0.371, p=0.001), and AP (r=-0.469, p<0.001). In multiple linear regression analysis, AP was independently associated with eGFR (p=0.035), beside the age and body surface area. An AP cut-off level of >0.71 had 84% sensitivity and 72% specificity in predicting eGFR of <90 mL/min per 1.72 m² (receiver–operating characteristic area under curve: 0.851, 95% CI: 0.760–0.942, p<0.001).

Conclusion:

We found an independent relationship between invasively measured AP and eGFR in patients with coronary artery disease. Moreover, a higher AP may predict lower eGFR. These results may be utilized to predict eGFR from AP during invasive procedures.

High Serum Osteoprotegerin Is Associated with Arterial Stiffness in Kidney Transplant Patients

Osteoprotegerin (OPG) is a cytokine that regulates bone resorption by inhibiting osteoclastogenesis, and OPG has been implicated in the process that causes vascular stiffness. An increase in serum OPG level has been associated with the development of arterial stiffness. Kidney transplant (KT) patients are susceptible to aortic stiffness, which is considered to be a predictor of cardiovascular events in this patient population. Carotid-femoral pulse wave velocity (cfPWV) has emerged as a gold standard for non-invasive evaluation of aortic stiffness. The aim of this study was to evaluate the relationship between serum OPG concentration and cfPWV among KT patients. Fasting blood samples were obtained from 57 KT patients and their cfPWV was measured using applanation tonometry. The serum OPG levels were measured using an enzyme-linked immunosorbent assay. Univariable linear regression analysis showed that the cfPWV in KT patients was significantly and positively correlated with age, body weight, waist circumference, body mass index, log-creatinine, systolic blood pressure, diastolic blood pressure, pulse pressure, and the log-OPG concentration. KT patients with metabolic syndrome had higher cfPWV values than those without metabolic syndrome (P = 0.036), which indicates a higher incidence of aortic stiffness in this patient population. Multivariable forward stepwise linear regression analysis of the significant variables showed that the log-OPG (P = 0.001), the log-creatinine (P = 0.004), and the SBP (P = 0.005) remained as independent and positive predictors of cfPWV values. These findings indicate that serum OPG levels are positively associated with cfPWV in KT patients.

Changes in Vascular Tone Occur Early During Hemodialysis Treatments Independently of Volume Reduction

Hypotension commonly occurs during hemodialysis (HD). Hypotension can result from an absolute reduction in plasma volume following excessive ultrafiltration or from a reduction in vascular tone. We hypothesized that changes in vascular tone could occur during dialysis. Aortic pulse wave velocity (aPWV) was measured in 197 HD patients, mean age 63.3 ± 16.6 years, 62% male, 49% diabetic, during a single HD session. aPWV did not change (9.6 ± 2.2 vs. 9.6 ± 2.2 m/s) with HD. Systolic blood pressure (SBP) declined from 151 ± 31 to 147 ± 32 after 20 min and to 140 ± 36 mm Hg on completion of HD (P < 0.05), with an ultrafiltration volume of 2.2 ± 0.9 L over a 3.9 ± 0.4 h HD session. Aortic SBP declined from 154 ± 32 to 146 ± 29 after 20 min and 143 ± 35 at the end of HD, P < 0.001. Aortic augmentation index (Aortic Aix) decreased from 65% (52-79%) to 36.7% (23.3-52.9%) by 20 min and to 34.3 (15.1-49.1%) on completion of HD (P < 0.05), and brachial augmentation index (brachial Aix) from 5.7% (-25.2 to 27.5%) to -1.9% (-2.2 to 30.1%) and -6.6% (-44 to 22.7%), respectively, P < 0.05. Diastolic reflection area (DRA) increased from 36.7 (27.9-46.3) to 40.4 (32.2-51) after 20 min and 47.1 (34.2-60.5) on completion of HD, P < 0.05. We report changes in arterial tone within 20 min of starting HD, when minimal ultrafiltration has occurred, suggesting that volume changes may not be the only predisposing cause of intradialytic hypotension. The combination of a fall in SBP and a rise in DRA would suggest a reduction in coronary blood flow in keeping with reports of "myocardial stunning" during HD.

Aortic Blood Flow Reversal Determines Renal Function

Aortic stiffness determines the glomerular filtration rate (GFR) and predicts the progressive decline of the GFR. However, the underlying pathophysiological mechanism remains obscure. Recent evidence has shown a close link between aortic stiffness and the bidirectional (systolic forward and early diastolic reverse) flow characteristics. We hypothesized that the aortic stiffening–induced renal dysfunction is attributable to altered central flow dynamics. In 222 patients with hypertension, Doppler velocity waveforms were recorded at the proximal descending aorta to calculate the reverse/forward flow ratio. Tonometric waveforms were recorded to measure the carotid-femoral (aortic) and carotid-radial (peripheral) pulse wave velocities, to estimate the aortic pressure from the radial waveforms, and to compute the aortic characteristic impedance. In addition, renal hemodynamics was evaluated by duplex ultrasound. The estimated GFR was inversely correlated with the aortic pulse wave velocity, reverse/forward flow ratio, pulse pressure, and characteristic impedance, whereas it was not correlated with the peripheral pulse wave velocity or mean arterial pressure. The association between aortic pulse wave velocity and estimated GFR was independent of age, diabetes mellitus, hypercholesterolemia, and antihypertensive medication. However, further adjustment for the aortic reverse/forward flow ratio and pulse pressure substantially weakened this association, and instead, the reverse/forward flow ratio emerged as the strongest determinant of estimated GFR ( P =0.001). A higher aortic reverse/forward flow ratio was also associated with lower intrarenal forward flow velocities. These results suggest that an increase in aortic flow reversal (ie, retrograde flow from the descending thoracic aorta toward the aortic arch), caused by aortic stiffening and impedance mismatch, reduces antegrade flow into the kidney and thereby deteriorates renal function.

Associations between blood pressure responses to acute stress and impaired renal function and serum uric acid level

The study aimed to examine correlations between blood pressure (BP) responses to direct laryngoscopy and tracheal intubation and parameters of renal function, serum uric acid (SUA) level, and mean preoperative BP. Fifty-four patients (≥ 40 years) who were scheduled for oral surgery were analyzed. General anesthesia was induced by the rapid sequence method without opioid analgesics. Systolic and diastolic BP (SBP, DBP) in the operation room were measured when an electrocardiogram, a BP cuff, and a pulse oximetry probe were attached to the patients (T1) and immediately after the trachea was intubated (T2). The ΔSBP was defined as the difference between SBP at T2 and T1. The increasing rate of SBP (ΔSBPr) was defined as ΔSBP/SBP at T1. SBP at T2 was associated with increasing age (R = 0.44), serum creatinine (R = 0.32), SUA (R = 0.30), mean preoperative SBP and DBP (R = 0.54 and 0.37, respectively), and reduced estimated glomerular filtration rate (eGFR) (R = -0.44). Serum creatinine and SUA were positively associated, and eGFR was negatively associated with ΔSBP (R = 0.36, 0.34, and -0.29) and ΔSBPr (R = 0.39, 0.37, and -0.29). Multivariate regression analysis revealed that age and mean preoperative SBP was independently associated with SBP at T2, and serum creatinine was independently associated with ΔSBP and ΔSBPr. These findings suggested that elevated serum creatinine level, as well as elevated preoperative BP level, was associated with enhanced BP responses to acute stress in middle-aged to elderly patients.

A high normal ankle-brachial index is associated with proteinuria in a screened cohort of Japanese: the Okinawa Peripheral Arterial Disease Study

OBJECTIVES

We hypothesized that ankle-brachial index (ABI) increased with age as a result of arterial stiffness, and decreased when flow-limiting atherosclerotic stenosis occurred in the lower limbs. As arterial stiffness is associated with proteinuria, we investigated the relationship between ABI and prevalence of proteinuria.

METHODS

A cross-sectional study of ABI and proteinuria with 13,193 participants aged 21-89 years (53% women) from health checkups between July 2003 and March 2010 was conducted. ABI was measured using the automatic oscillometric method, and stratified into four groups: ABI ≤ 0.9 (low); 0.9 < ABI <1.0 (borderline low); 1.0 ≤ ABI <1.2 (normal); and 1.2 ≤ ABI <1.4 (high normal).

RESULTS

In participants with ABI at least 1.0, ABI was positively correlated with SBP, pulse pressure, and brachial-ankle pulse wave velocity. In participants with ABI less than 1.0, all indices were negatively correlated with ABI. The prevalence of proteinuria, defined as ≥ 1+ by dipstick, was significantly higher in low (23%) and high normal ABI (10%) compared with borderline low (6%) and normal ABI (7%). In participants at least 60 years, proteinuria was significantly associated with only low ABI [odds ratio (OR) 3.22, 95% confidence interval 1.34-7.41] compared with normal ABI before and after multivariable adjustment. In participants less than 60 years, adjusted OR for proteinuria was only significantly associated with high normal ABI (OR 1.32, 95% confidence interval 1.01-1.74).

CONCLUSION

High normal ABI in younger participants may be a result of arterial stiffness and associated with proteinuria.

Arterial stiffness: an independent determinant of adaptive glomerular hyperfiltration after kidney donation

After kidney donation, the remaining kidney tends to hyperfiltrate, thus limiting the initial loss of renal function. The potential determinants of this adaptive glomerular hyperfiltration (GHF) and specifically the influence of arterial function are poorly known. In 45 normotensive healthy kidney donors [51 ± 10 yr (mean ± SD), 39 females], glomerular filtration rate (GFR) was measured as the clearance of continuously infused (99m)Tc-DTPA and timed urine collections at baseline, i.e., before donation, and 1 yr after donation. GHF was computed as postdonation GFR minus half of baseline GFR. Arterial function was assessed as baseline carotid-femoral pulse wave velocity (PWV) and carotid augmentation index (AIx). After kidney donation, no significant change in blood pressure (BP) was observed, but two subjects developed hypertension. GFR decreased from 107 ± 19 to 73 ± 15 ml·min(-1)·1.73 m(-2), and mean GHF was 20 ± 10 ml·min(-1)·1.73 m(-2). In univariate analysis, GHF was inversely correlated to age (r(2) = 0.24, P = 0.01), baseline PWV (r(2) = 0.23, P = 0.001), and Aix (r(2) = 0.11, P = 0.031). Nevertheless, GHF was not correlated to baseline peripheral or central BP. In multivariate analysis, baseline PWV, but not AIx, remained inversely correlated to GHF, independently of age, baseline mean BP, and GFR (model r(2) = 0.34, P < 0.001). In healthy subjects selected for renal donation, increased arterial stiffness is associated with decreased postdonation compensatory hyperfiltration.

Compliance Index, a Marker of Peripheral Arterial Stiffness, may Predict Renal Function Decline in Patients with Chronic Kidney Disease

BACKGROUND

Compliance index derived from digital volume pulse (CI-DVP), measuring the relationship between volume and pressure changes in fingertip, is a surrogate marker of peripheral arterial stiffness. This study investigated if CI-DVP can predict renal function deterioration, cardiovascular events and mortality in patients with chronic kidney disease (CKD).

METHODS

In this prospective observational study, 149 CKD patients were included for final analysis. CI-DVP and brachial-ankle pulse wave velocity (baPWV) were measured, decline in renal function was assessed by the estimated glomerular filtration rate (eGFR) slope. Composite renal and cardiovascular outcomes were evaluated, including ≥50% eGFR decline, start of renal replacement therapy, and major adverse events.

RESULTS

Patients in CKD stages 3b to 5 had higher baPWV and lower CI-DVP values than those in patients with CKD stages 1 to 3a. Stepwise multivariate linear regression analysis showed that lower CI-DVP (p =0.0001) and greater proteinuria (p =0.0023) were independent determinants of higher eGFR decline rate. Multivariate Cox regression analysis revealed that CI-DVP (HR 0.68, 95% CI 0.46-1.00), baseline eGFR (HR 0.96, 95% CI 0.94-0.98) and serum albumin (HR 0.17, 95% CI 0.07-0.42) were independent predictors for composite renal and cardiovascular outcomes.

CONCLUSIONS

Compliance index, CI-DVP, was significantly associated with renal function decline in patients with CKD. A higher CI-DVP may have independent prognostic value in slower renal function decline and better composite renal and cardiovascular outcomes in CKD patients.

Serum osteoprotegerin is associated with arterial stiffness assessed according to the cardio-ankle vascular index in hypertensive patients

AIM

Arterial stiffness is recognized to be an independent risk factor for cardiovascular morbidity and mortality. Recent studies have found that osteoprotegerin (OPG) is associated with increased pulse wave velocity and may reflect endothelial dysfunction. The aim of this study was to evaluate the relationship between the serum OPG level and arterial stiffness in hypertensive patients using the cardio-ankle vascular index (CAVI).

METHODS

Fasting blood samples were obtained from 115 hypertensive patients and 52 healthy participants. The CAVI value was derived using the waveform device (CAVI-VaSera VS-1000). The serum OPG levels were measured using a commercially available enzyme-linked immunosorbent assay. A CAVI value of ≥9 defined the high arterial stiffness group.

RESULTS

Sixty-five hypertensive patients (56.5%) were included in the high arterial stiffness group. Diabetes (p=0.032), smoking (p=0.044), age (p < 0.001), systolic blood pressure (p=0.001), diastolic blood pressure (p=0.024), pulse pressure (p=0.046) and the creatinine (p=0.013) and serum OPG (p < 0.001) levels were higher in the high arterial stiffness group than in the low arterial stiffness group, while the glomerular filtration rate (p=0.003) was lower in the high arterial stiffness group than in the low arterial stiffness group among the hypertensive patients. The results of the Spearman's rank correlation coefficient test also indicated a strong positive correlation between the OPG and CAVI values (r=0.484, p < 0.001) in the hypertensive patients. In addition, a multivariate logistic regression analysis showed that age (odds ratio: 1.162, 95% confidence interval (CI): 1.070-1.263, p < 0.001), diastolic blood pressure (odds ratio: 1.109, 95% CI: 1.033-1.190, p=0.004), and serum OPG level (odds ratio: 1.275, 95% CI: 1.030-1.580, p=0.026) were independent predictors of arterial stiffness in hypertensive patients.

CONCLUSIONS

The serum OPG level is positively associated with arterial stiffness in hypertensive patients.

Lower glomerular filtration rate is associated with higher systemic vascular resistance in patients without prevalent kidney disease

The authors examined the association between estimated glomerular filtration rate (eGFR), calculated using the Chronic Kidney Disease Epidemiology Collaboration creatinine-cystatin C equation, and hemodynamics in 556 normotensive or never-treated hypertensive patients without kidney disease (mean age, 46 years). Hemodynamic variables were recorded using pulse wave analysis and whole-body impedance cardiography. The mean eGFR was 98 mL/min/1.73 m(2) (range, 64-145 mL/min/1.73 m(2) and one third of the patients had values below 92, while none had proteinuria. In linear regression analyses adjusted for differences in age, weight:height ratio, low-density lipoprotein cholesterol, and sex, significant associations were found between lower eGFR and higher systolic (P=.001) and diastolic blood pressure (P<.001) and higher systemic vascular resistance (P=.001). There was no association between eGFR and cardiac output or extracellular volume. In the absence of clinical kidney disease, lower eGFR was associated with higher blood pressure and systemic vascular resistance. Therefore, early impairment in kidney function may be involved in the pathogenesis of essential hypertension.

Association of serum osteoprotegerin levels with carotid-femoral pulse wave velocity in hypertensive patients

Osteoprotegerin (OPG) has been implicated in the process of vascular stiffness. The aim of this study was to evaluate the relationship between fasting serum OPG concentration and carotid-femoral pulse wave velocity (c-f PWV) in hypertensive patients. Fasting blood samples were obtained from 184 participants with or without hypertension. c-f PWV were performed by SphygmoCor system. Serum OPG levels were measured using a commercially available enzyme-linked immunosorbent assay. Hypertensive patients who had diabetes had higher c-f PWV levels than those without diabetes (P=.031). The univariable linear regression analysis showed that age (P<.001), systolic blood pressure (P=.003), pulse pressure (r=0.287; P=.003), log-BUN (P=.011), Cre (P<.001), and log-OPG concentration (P<.001) were positively correlated with c-f PWV levels, while the glomerular filtration rate (P=.005) and HDL-C level (P=.024) was negatively correlated with c-f PWV levels among the hypertensive patients. Multivariable forward stepwise linear regression analysis of the significant variables also showed that log-OPG (β=0.312, regression coefficient: 1.736; 95% confidence interval, 0.809-2.663; P<.001) was still an independent predictor of c-f PWV levels in hypertensive patients. Serum OPG levels positively associated with c-f PWV levels in hypertensive patients.

Deterioration in renal function is associated with increased arterial stiffness

BACKGROUND

Higher levels of baseline pulse wave velocity (PWV) have been associated with longitudinal decline in renal function in patients with kidney disease. We examined longitudinal decline in renal function in relation to levels of PWV. We hypothesized that longitudinal decline in renal function in a community-based, nonclinic sample would be associated with higher levels of PWV.

METHODS

We conducted a 4-5 year longitudinal study with 482 community-living individuals free from acute stroke, dementia, and end-stage renal disease (mean age = 60.9 years; 59% women; 93.2% white; 10% with diabetes mellitus; mean estimated glomerular filtration rate (eGFR) = 79.2 ml/min/1.73 m2). Multiple linear regression analyses were used to examine the association between changes in renal function (eGFR and serum creatinine) from baseline to follow-up and PWV levels at follow-up, the outcome measure. Regression coefficients were adjusted for age, sex, education, race/ethnicity, weight, activity level, mean arterial pressure, treatment of hypertension, and cardiovascular risk factors.

RESULTS

With adjustment for covariables, decline in renal function was associated with higher levels of PWV over a mean follow-up of 4.68 years.

CONCLUSIONS

Decline in renal functioning from baseline levels measured 4-5 years before measurement of PWV is related to higher levels of PWV in a community sample.

Estimated glomerular filtration rate is associated with both arterial stiffness and N-terminal pro-brain natriuretic peptide in newly diagnosed hypertensive patients

Even a slight decrease in the glomerular filtration rate (GFR) is an independent risk factor for cardiovascular disease. Arterial stiffness, left ventricular hypertrophy and N-terminal pro-brain natriuretic peptide (NT-proBNP) are independent risk factors for cardiovascular disease, which are particularly common in end-stage renal disease. We aimed to evaluate the association between GFR with arterial stiffness, left ventricle mass (LVM) and NT-proBNP in hypertensive subjects with normal to mildly impaired renal function. The study population consisted of 285 newly diagnosed hypertensive patients (mean age; 49.9 ± 11.8 years). GFR was estimated (eGFR) by the Modification of Diet in Renal Disease formula. Pulse wave velocity (PWV) and augmentation index (AIx), which reflects arterial stiffness, were calculated using the single-point method via the Mobil-O-Graph® ARCsolver algorithm. LVM was obtained by echocardiography. Plasma NT-proBNP was measured by electrochemiluminescence. The patients were divided into two groups according to the median eGFR value (eGFRlow group <101 ml/min/1.73 m(2) and eGFRhigh group ≥ 101 ml/min/1.73 m(2)). LVM and NT-proBNP values were higher in eGFRlow group compared with eGFRhigh group (p<0.05). Pulse wave velocity and augmentation index values were higher in eGFRlow group compared with eGFRhigh group (p<0.05, for all). Multiple linear regression analysis showed that eGFR was independently associated with PWV (β=-0.422, p<0.001) and NT-proBNP (β=-0.404, p<0.001). Present study showed that eGFR was independently associated with PWV and NT-proBNP values. Importantly, these findings may explain, in part, the increase in cardiovascular risk in with slightly impaired renal function.

Pulse-Wave Analysis of Optic Nerve Head Circulation Is Significantly Correlated with Kidney Function in Patients with and without Chronic Kidney Disease

Aim. To determine whether there is a significant correlation between the optic nerve head (ONH) circulation determined by laser speckle flowgraphy (LSFG) and kidney function. Materials. Seventy-one subjects were investigated. The estimated glomerular filtration rate (GFR) and serum creatinine, cystatin C, and urinary albumin excretion were measured. The ONH circulation was determined by an analysis of the pulse wave of LSFG, and this parameter was named blowout time (BOT). Chronic kidney disease (CKD) was defined to be present when the estimated GFR was <60 mL/min per 1.73 m². Pearson's correlation coefficients were used to determine the relationship between the BOT and the kidney function. We also examined whether there were significant differences in all parameters in patients with and without CKD. Results. BOT was significantly correlated with the level of creatinine (r = −0.24, P = 0.04), the estimated GFR (r = 0.42, P = 0.0003), cystatin C (r = −0.29, P = 0.01), and urinary albumin excretion (r = −0.29, P = 0.01). The BOT level in subjects with CKD was significantly lower than that in subjects without CKD (P = 0.002). Conclusion. BOT in ONH by LSFG can detect the organ damage such as kidney dysfunction, CKD.

Impaired renal function impacts negatively on vascular stiffness in patients with coronary artery disease

BACKGROUND

Chronic kidney disease (CKD) and coronary artery disease (CAD) are independently associated with increased vascular stiffness. We examined whether renal function contributes to vascular stiffness independently of CAD status.

METHODS

We studied 160 patients with CAD and 169 subjects without CAD. The 4-variable MDRD formula was used to estimate glomerular filtration rate (eGFR); impaired renal function was defined as eGFR <60 mL/min. Carotid-femoral pulse wave velocity (PWV) was measured with the SphygmoCor® device. Circulating biomarkers were assessed in plasma using xMAP® multiplexing technology.

RESULTS

Patients with CAD and impaired renal function had greater PWV compared to those with CAD and normal renal function (10.2 [9.1;11.2] vs 7.3 [6.9;7.7] m/s; P < 0.001). In all patients, PWV was a function of eGFR (β = -0.293; P < 0.001) even after adjustment for age, sex, systolic blood pressure, body mass index and presence or absence of CAD. Patients with CAD and impaired renal function had higher levels of adhesion and inflammatory molecules including E-selectin and osteopontin (all P < 0.05) compared to those with CAD alone, but had similar levels of markers of oxidative stress.

CONCLUSIONS

Renal function is a determinant of vascular stiffness even in patients with severe atherosclerotic disease. This was paralleled by differences in markers of cell adhesion and inflammation. Increased vascular stiffness may therefore be linked to inflammatory remodeling of the vasculature in people with impaired renal function, irrespective of concomitant atherosclerotic disease.

Heart rate significantly influences the relationship between atrial fibrillation and arterial stiffness

BACKGROUND

Atrial fibrillation (AF) and vascular disease share several risk factors and the two diseases often coexist. Heart rate (HR) is reported to be a major determinant of arterial stiffness. AF patients often have a transiently or persistently rapid HR. Hence, this study was to assess whether AF was significantly associated with arterial stiffness and HR could significantly influence the relationship between AF and arterial stiffness. Besides, we also determine the main correlates of arterial stiffness in AF patients and see whether HR was correlated with arterial stiffness in these patients.

METHODS

We included 166 AF and 1336 non-AF patients from subjects arranged for echocardiographic examinations. Arterial stiffness was assessed by brachial-ankle pulse wave velocity (baPWV).

RESULTS

Compared to non-AF patients, AF patients had a higher baPWV (p <0.001). In a multivariate model, including covariates of age, sex, blood pressures and so on, the presence of AF was significantly associated with baPWV (β = 0.079, P = 0.001). However, further adjustment for HR made this association disappear (β = 0.005, P = 0.832). In addition to age and systolic blood pressure, increased HR (β = 0.309, p <0.001) was a major determinant of increased baPWV in our AF patients.

CONCLUSIONS

This study demonstrated the presence of AF was associated with increased baPWV, but this association became insignificant after further adjustment for HR, which suggested HR could significantly influence the relationship between AF and baPWV. Besides, HR was positively correlated with arterial stiffness in our AF patients.

Pulse pressure, arterial stiffness, and end-organ damage

Whereas larger arteries participate in the dampening of blood pressure (BP) oscillations resulting from intermittent ventricular ejection, smaller arteries steadily deliver an adequate supply of blood from the heart to the peripheral organs. Numerous active mechanisms are involved in this process. Cyclic stress acts differently from steady stress, inducing stronger and stiffer material of the vessel wall than under static conditions. Cyclic strain participates in the phenotypic plasticity of smooth muscle cells, initiates transduction mechanisms and induces the transcriptional profile of mechanically induced genes. Finally, the autoregulatory mechanism protecting the brain, heart and kidney from cardiovascular (CV) damage differ markedly according to their localization. Whereas the heart is dependent on pulsatile forces, owing to the diastolic perfusion of coronary arteries, the brain and the kidney are rather influenced by steady mechanical forces. For the kidney, the transmission of pulsatile pressure may greatly contribute to glomerular sclerosis in the elderly.

The association between chronic kidney disease and cardiovascular disease risk factors in atomic bomb survivors

Atomic bomb (A-bomb) radiation is associated with cardiovascular disease (CVD) and metabolic CVD risk factors. Chronic kidney disease (CKD) is also known to be a risk factor for CVD and little is known whether CKD is associated with A-bomb radiation. To examine whether CKD is associated with CVD risk factors or with A-bomb radiation in A-bomb survivors, we classified renal dysfunction in 1,040 A-bomb survivors who were examined in 2004-2007 as normal [n = 121; estimated glomerular filtration rate (eGFR) ≥ 90 ml/min/1.73 m(2)]; mild (n = 686; eGFR 60-89 ml/min/1.73 m(2)); moderate (n = 217; eGFR 30-59 ml/min/1.73 m(2)); or severe (n = 16; eGFR <30 ml/min/1.73 m(2)). Also, we diagnosed subjects in the moderate and severe renal dysfunction groups as having CKD (n = 233; eGFR <59 ml/min/1.73 m(2)). After adjusting for age, gender, and smoking and drinking habits, we looked for an association between renal dysfunction and hypertension, diabetes mellitus (DM), hyperlipidemia, and metabolic syndrome (MetS), and between renal dysfunction and A-bomb radiation. Hypertension [odds ratio (OR), 1.57; 95% confidence interval (CI), 1.12-2.20, P = 0.009]; DM (OR, 1.79; 95% CI, 1.23-2.61, P = 0.002); hyperlipidemia (OR, 1.55; 95% CI, 1.12-2.14, P = 0.008); and MetS (OR, 1.86; 95% CI, 1.32-2.63, P < 0.001) were associated with CKD (moderate/severe renal dysfunction), and hyperlipidemia and MetS were also associated with mild renal dysfunction. CKD (OR/Gy, 1.29; 95% CI, 1.01-1.63, P = 0.038) and severe renal dysfunction (OR/Gy, 3.19; 95% CI, 1.63-6.25, P < 0.001) were significantly associated with radiation dose. CKD associated with radiation may have played a role in the development of CVD among A-bomb survivors.

Association of glomerular filtration rate with arterial stiffness in Chinese women with normal to mildly impaired renal function

Objective

Both decreased glomerular filtration rate (GFR) and arterial stiffness were considered as risk factors for atherosclerosis. Previous studies have suggested the association between central arterial stiffness and the degree of GFR loss. Whether decreased GFR contributes to peripheral artery stiffness remains controversial. Moreover, data analyzed from a cohort of Chinese women are rare. Our aim was to explore the relationship between GFR and regional arterial stiffness in Chinese women.

Methods

In this cross-sectional study, we randomly recruited 1131 adult women residents with GFR ≥ 60 mL/min per 1.73 m² estimated by the Chinese Modification of Diet in Renal Disease equation from three large communities. Central and peripheral arterial stiffness were estimated simultaneously by measuring carotid-femoral pulse wave velocity (PWVcf) and carotid-radial PWV (PWVcr) using a validated automatic device. Augmentation Index at heart rate 75 beats/minutes (AIx-75) was measured by pulse wave analysis as a composite parameter reflecting both large and distal arterial properties.

Results

The mean estimated GFR (eGFR) of the study group was 100.05 ± 23.26 mL/minute per 1.73 m². Subjects were grouped by tertiles of eGFR level. PWVcf and AIx-75 increased ongoing from the top to the bottom eGFR tertile, while the values of PWVcr were comparable. Both univariate Pearson correlations and multiple stepwise regression analyses showed that eGFR significantly correlated to PWVcf, but not to PWVcr and AIx-75.

Conclusions

In Chinese women with normal to mildly impaired renal function, decreased eGFR affected carotid-to-femoral rather than carotid-to-radial stiffening. This provides rational to conduct future prospective studies to investigate predictors of atherosclerosis in this population.

Decreased estimated glomerular filtration rate (eGFR) is not an independent risk factor of arterial stiffness in Chinese women

Recent studies suggest that decreased estimated glomerular filtration rate (eGFR) and uric acid (UA) may be independent risk factors for arterial stiffness (AS). As serum UA level is linked to renal function, we hypothesize that decreased eGFR may be not an independent risk factor of AS, but may be related to UA level. In this study, we aimed to validate this hypothesis in a large community-based Chinese population. A total of 13,899 people were selected from the Cardiovascular Risk Survey (CRS) from October 2007 to March 2010. Pulse wave velocity (PWV) was calculated using the established methods. The relationships between eGFR, fasting blood glucose (FBG), UA and PWV were analyzed with multivariate linear regression. We found that PWV was significantly correlated to FBG (r = 0.173, p < 0.001) and UA (r = 0.177, p < 0.001), and inversely correlated to eGFR (r = - 0.161, p < 0.001). A multivariable regression analysis revealed that FBG (β = 0.056, p < 0.001) and UA (β = 0.039, p < 0.001), but not eGFR (β = - 0.011, p = 0.062) were significantly related to elevation of PWV. In women, eGFR was not an independent risk factor of AS with progressively decreasing renal function (all p > 0.05). However, in men, eGFR was associated with PWV in subjects with eGFR < 60 ml/min/1.73 m(2). Our results suggest that decreased eGFR is not independently associated with AS in Chinese women.

Age- and sex-specific reference limits for creatinine, cystatin C and the estimated glomerular filtration rate

BACKGROUND

Early detection of patients with chronic kidney disease is of great importance. This study developed reference limits for serum creatinine and serum cystatin C concentrations and for the estimated glomerular filtration rate (eGFR) in healthy subjects from the general population aged 25-65 years.

METHODS

This study defined a reference population including 985 subjects from the first follow-up of the Study of Health in Pomerania. Serum creatinine was measured with a modified kinetic Jaffé method. Serum cystatin C was measured with a nephelometric assay. The eGFR was calculated from serum creatinine according to the Cockcroft-Gault (eGFR(CG)) and the Modification of Diet in Renal Disease (eGFR(MDRD)) equation, respectively, as well as from serum cystatin C according to the formula by Larsson (eGFR(Larsson)). Non-parametric quantile regression was used to estimate the reference limits. For serum creatinine and serum cystatin C the 95th percentile and for eGFR(CG), eGFR(MDRD) and eGFR(Larsson) the 5th percentile were selected as reference limits. All data was weighted to reflect the age- and sex-structure of the German population in 2008.

RESULTS

The reference limits for serum creatinine (men: 1.11-1.23 mg/dL; women: 0.93-1.00 mg/dL) and serum cystatin C levels (men: 0.92-1.04 mg/L; women: 0.84-1.02 mg/L) increased with advancing age. The reference limits for eGFR decreased with increasing age (eGFR(CG) men: 106.0-64.7 mL/min, women 84.4-57.9 mL/min; eGFR(MDRD) men: 82.5-62.2 mL/min/1.73 m², women 75.0-58.2 mL/min/1.73 m²; eGFR(Larsson) men: 85.5-72.9 mL/min, women 94.5-75.7 mL/min).

CONCLUSIONS

This study presents age- and sex-specific reference limits for five measures of renal function based on quantile regression models.

Systolic pressure, diastolic pressure, or pulse pressure as a cardiovascular risk factor in renal disease

Chronic kidney disease is a leading global health problem with an increasing prevalence. Hypertension is present in most patients with chronic kidney disease, and hypertension-related nephrosclerosis is a top cause of progressive renal damage and end-stage renal disease. Systolic blood pressure (BP) and pulse pressure, together with nocturnal BP, are the most important factors favoring the progression of renal failure. Consequently, strict control of BP and other cardiovascular risk factors is required, including an adequate degree of suppression of the renin-angiotensin system in every patient.

Aortic stiffness is associated with vascular calcification and remodeling in a chronic kidney disease rat model

Increased aortic pulse-wave velocity (PWV) reflects increased arterial stiffness and is a strong predictor of cardiovascular risk in chronic kidney disease (CKD). We examined functional and structural correlations among PWV, aortic calcification, and vascular remodeling in a rodent model of CKD, the Lewis polycystic kidney (LPK) rat. Hemodynamic parameters and beat-to-beat aortic PWV were recorded in urethane-anesthetized animals [12-wk-old hypertensive female LPK rats ( n = 5)] before the onset of end-stage renal disease and their age- and sex-matched normotensive controls (Lewis, n = 6). Animals were euthanized, and the aorta was collected to measure calcium content by atomic absorption spectrophotometry. A separate cohort of animals ( n = 5/group) were anesthetized with pentobarbitone sodium and pressure perfused with formalin, and the aorta was collected for histomorphometry, which allowed calculation of aortic wall thickness, medial cross-sectional area (MCSA), elastic modulus (EM), and wall stress (WS), size and density of smooth muscle nuclei, and relative content of lamellae, interlamellae elastin, and collagen. Mean arterial pressure (MAP) and PWV were significantly greater in the LPK compared with Lewis (72 and 33%, respectively) animals. The LPK group had 6.8-fold greater aortic calcification, 38% greater aortic MCSA, 56% greater EM/WS, 13% greater aortic wall thickness, 21% smaller smooth muscle cell area, and 20% less elastin density with no difference in collagen fiber density. These findings demonstrate vascular remodeling and increased calcification with a functional increase in PWV and therefore aortic stiffness in hypertensive LPK rats.

Glomerular hemodynamics and arterial function in normal individuals

OBJECTIVE

To determine the relationship between arterial function (stiffness and wave reflection) and glomerular hemodynamics.

METHODS

In 49 healthy normotensive individuals, glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured by urinary clearances of 99mTC-DTPA and 131I-hippuran, respectively. Filtration fraction was computed as GFR/ERPF. Arterial stiffness was estimated by carotid-femoral pulse wave velocity (PWV). Wave reflection was evaluated by carotid augmentation index (AIx), reflection magnitude and the round-trip travel time of the pressure wave.

RESULTS

PWV and round-trip travel time were not independently correlated with any renal hemodynamic parameter or urinary albumin-creatinine ratio (UACR). AIx and reflection magnitude were directly correlated with filtration fraction (r = 0.35 and 0.37, respectively) and UACR (r = 0.43 and 0.53, respectively). When the population was divided into quartiles of reflection magnitude, filtration fraction and UACR progressively increased from the lowest to the highest quartile and after adjustment for age, mean arterial pressure, heart rate but also sex for UACR (P linear trend = 0.031 and 0.001, respectively).

CONCLUSION

It is suggested that in normal individuals, the amplitude of wave reflection but not arterial stiffness is associated with signs evocative of increased glomerular pressure (filtration fraction and UACR), independently of systemic blood pressure.