Increased renal resistive index in patients with essential hypertension: a marker of target organ damage

Renal haemodynamics and severity of carotid atherosclerosis in hypertensive patients with and without impaired renal function

BACKGROUND AND AIM

Renal resistance index (RRI), assessed by Duplex-Doppler sonography, has been classically considered as a mere expression of intrarenal vascular resistance. Recent studies, however, have showed that RRI is also influenced by upstream factors, especially arterial compliance, confirming its possible role as a marker of systemic vascular alterations. Several studies have shown that carotid intima-media thickness (cIMT) and carotid plaques (cP), assessed by ultrasonography, are documented markers of subclinical organ damage as well as expression of progressive atherosclerotic disease, and that they get worse with the progressive deterioration of renal function. The study was aimed to evaluate the relationship between RRI and severity of carotid atherosclerosis in hypertensive subjects with and without impaired renal function.

METHODS AND RESULTS

The study population, including 263 hypertensive patients (30-70 years), was split into 3 groups based on cIMT and presence of cP (cIMT ≤ 0.9 mm and no cP; cIMT > 0.9 mm and no cP; cP). All patients were also divided into 2 subgroups (normal renal function; CKD stage I-IV). A stepwise increase in RRI corresponding to the groups of progressive severity of carotid atherosclerosis was observed (respectively 0.61 ± 0.07, 0.65 ± 0.06, 0.68 ± 0.06; p < 0.001). A strong positive correlation was observed between RRI and cIMT in the whole population (r = 0.43; p < 0.001) and in the subgroups with (r = 0.42; p < 0.001) and without (r = 0.39; p < 0.001) CKD. These associations remained statistically significant even after adjustment for various confounding factors.

CONCLUSION

Showing a close association between RRI and severity of carotid atherosclerosis, our results strengthen the concept that RRI is a marker of systemic vascular changes.

Prevalence of renal artery disease and its prognostic significance in patients undergoing coronary bypass grafting

Several studies demonstrated the prognostic importance of renal failure and peripheral artery disease in patients undergoing coronary artery bypass grafting (CABG), but data regarding the prognostic value of renal artery disease in this context are scarce. We aimed to study the prevalence and prognostic value of renal artery disease in patients undergoing CABG. We assessed by duplex ultrasound the renal arteries of 429 consecutive patients who underwent CABG, of whom 401 had satisfactory imaging quality to detect >60% renal artery stenosis (RAS) and/or an elevated resistive index (ERI>0.80). Of the 401 subjects included (age 68±10 years, 83% men), 40 (10%) had RAS and 35 (9%) had ERI. Nine patients (2.2%) had both conditions. Patients were followed up for 12.4±7.0 months. The primary outcome was composite, including 30-day death, stroke, and/or myocardial infarction. In a multivariate model adjusted for age, gender, cardiovascular (CV) risk factors, renal function, chronic obstructive pulmonary disease, the use of off-pump CABG, CV co-morbidities, and drugs, the presence of ERI was strongly associated with the occurrence of the composite outcome (odds ratio 4.3, 95% confidence interval 1.7 to 9.9, p=0.0006). Similarly, ERI, not RAS, was significantly associated with the 30-day acute kidney disease and the midterm mortality, as well as fatal and nonfatal CV events. In conclusion, regardless of renal function and other factors, the renal resistive index is a strong predictor of CV and renal events after CABG. Renal duplex ultrasound can identify a subgroup of patients at high risk of CABG.

Renal sympathetic denervation for the treatment of refractory hypertension

Resistant hypertension poses significant health concerns. There are strong demands for new and safe therapies to control resistant hypertension while addressing its common causes, specifically poor compliance to lifelong polypharmacy, lifestyle modifications, and physician inertia. The sympathetic nervous system plays a significant pathophysiological role in hypertension. Surgical sympathectomy for blood pressure reduction is an old but extremely efficacious therapeutic concept, now abandoned with the dawn of a safer contemporary pharmacology era. Recently, clinical studies have revealed promising results for safe and sustained blood pressure reduction with percutaneous renal sympathetic denervation. This is a novel, minimally invasive, device-based therapy, specifically targeting and ablating the renal artery nerves with radiofrequency waves without permanent implantation. There are also reported additional benefits in related comorbidities, such as impaired glucose metabolism, renal impairment, left ventricular hypertrophy, heart failure, and others. This review focuses on how selective renal sympathetic denervation works, its present and potential therapeutic indications, and its future directions.

Ultrasound Doppler renal resistive index: a useful tool for the management of the hypertensive patient

The Doppler-derived renal resistive index has been used for years in a variety of clinical settings such as the assessment of chronic renal allograft rejection, detection and management of renal artery stenosis, evaluation of progression risk in chronic kidney disease, differential diagnosis in acute and chronic obstructive renal disease, and more recently as a predictor of renal and global outcome in the critically ill patient. More recently, evidence has been accumulating showing that an increased renal resistive index not only reflects changes in intrarenal perfusion but is also related to systemic hemodynamics and the presence of subclinical atherosclerosis, and may thus provide useful prognostic information in patients with primary hypertension. On the basis of these results, the evaluation of renal resistive index has been proposed in the assessment and management of patients with primary hypertension to complement other signs of renal abnormalities.

The relationship between renal resistive index, arterial stiffness, and atherosclerotic burden: the link between macrocirculation and microcirculation

The renal resistive index (RRI) measured by Doppler sonography is a marker of microvascular status that can be generalized to the whole of the arterial tree. Its association with large-vessel dysfunction, such as arterial stiffness or the atherosclerotic burden, can help to establish physiopathological associations between macrocirculation and microcirculation. The authors conducted a cross-sectional study of hypertensive patients (n=202) and a healthy control group (n=16). Stiffness parameters, atherosclerotic burden, and determination of the RRI in both kidneys were performed. The average RRI was 0.69±0.08 and was significantly greater in patients with diabetes and chronic kidney disease. Renal resistive index positively correlated with age, creatinine, and albuminuria. Positive correlations were found with arterial stiffness parameters (pulse wave velocity, ambulatory arterial stiffness index, and 24-hour pulse pressure), as well as atherosclerotic burden and endothelial dysfunction measured as asymmetric dimethylarginine in serum. In the multivariate analysis, independent factors for increased RRI were age, renal function, 24-hour diastolic blood pressure, and arterial stiffness. The authors concluded that there is an independent association between renal hemodynamics and arterial stiffness. This, together with the atherosclerotic burden and endothelial dysfunction, suggests that there is a physiopathologic relationship between macrovascular and microvascular impairment.

Predictive role of renal resistive index for clinical outcome after revascularization in hypertensive patients with atherosclerotic renal artery stenosis: a monocentric observational study

Background

The present study evaluated the predictive value of renal resistive index (RI) for renal function and blood pressure (BP) outcome in hypertensive patients with unilateral atherosclerotic renal artery stenosis submitted to successful revascularization.

Methods

In 158 hypertensive patients with atherosclerotic renal artery stenosis RI was acquired. Twelve months after revascularization, they were classified on the basis of renal function and BP outcome as benefit (BP < 140/90 mmHg or diastolic BP reduction > 15 mmHg with the same of reduced drugs; decrease in glomerular filtration rate > 20%), or failure.

Results

Regarding renal function outcome, RI in the stenotic and in the contralateral kidney were significantly higher in patients with failure (n = 20) than in those with benefit (0.72 ± 0.11 vs 0.61 ± 0.11 and 0.76 ± 0.08 vs 0.66 ± 0.09, p < 0.05). Among different cutpoints generated, RI in the contralateral kidney >0.73 provided the largest area under the curve (0.77), and the highest sensitivity (80%) and specificity (72%). In the multivariate logistic regression analysis, RI in the contralateral kidney >0.73 was an independent predictor of a failure in renal function outcome.

Regarding BP outcome, patients with no benefit from revascularization (n = 60) had similar RI in the stenotic and contralateral kidney (p = ns), but presented higher pulse pressure, albuminuria and hypertension duration in comparison to patients with improved BP control.

Conclusions

RI in the contralateral kidney is an independent predictor of renal function outcome after successful revascularization in hypertensive patients with unilateral atherosclerotic renal artery stenosis, whereas it is not able to predict blood pressure outcome.

Abdominal aortic calcification and renal resistive index in patients with chronic kidney disease: is there a connection?

BACKGROUND

We aimed to evaluate the relationship between abdominal aortic calcification (AAC) and renal resistive index (RRI), parameters associated with cardiovascular outcome, in non-dialysis chronic kidney disease (CKD) patients.

METHODS

Seventy-seven stable patients mainly in CKD stages 3B and 4 (44 and 28%), median age 69 years, with a positive history of systemic atherosclerosis were prospectively enrolled. RRI, carotid intima-media thickness (IMT), Kauppila score for AAC (AACs), cardio-ankle vascular index (CAVI) and ankle-brachial index (ABI) were assessed. Traditional and non-traditional atherosclerosis risk factors were also evaluated.

RESULTS

Vascular (50%), diabetic (26%) and primary glomerular nephropathies (8 %) were the main causes of CKD. AAC was highly prevalent (77%). In the whole cohort, RRI was directly related to AACs (rs = 0.35, p < 0.001). AACs correctly identified patients with RRI >0.7 in 69% (56-81%) of cases, a cut-off of 5 resulting the best combination of sensitivity (65%) and specificity (68%). Compared to those with AACs <5, patients with AACs >5 were older, had higher serum cholesterol, C-reactive protein and IMT, lower ABI, but similar CAVI, estimated glomerular filtration rate, serum calcium and phosphate. In the whole cohort, AACs was negatively correlated with ABI (rs = -0.51, p < 0.001) and positively with IMT (rs = 0.27, p = 0.01), supporting a role for Kauppila score in integrating information on both intra- and extrarenal atherosclerosis.

CONCLUSIONS

As Kauppila score correlates with RRI in non-dialysis CKD patients, it could be a fast, convenient and relatively inexpensive tool for estimating RRI, and consequently the intrarenal vascular status, but further research is warranted.

Reference Values and Factors Associated With Renal Resistive Index in a Family-Based Population Study

Increased renal resistive index (RRI) has been recently associated with target organ damage and cardiovascular or renal outcomes in patients with hypertension and diabetes mellitus. However, reference values in the general population and information on familial aggregation are largely lacking. We determined the distribution of RRI, associated factors, and heritability in a population-based study. Families of European ancestry were randomly selected in 3 Swiss cities. Anthropometric parameters and cardiovascular risk factors were assessed. A renal Doppler ultrasound was performed, and RRI was measured in 3 segmental arteries of both kidneys. We used multilevel linear regression analysis to explore the factors associated with RRI, adjusting for center and family relationships. Sex-specific reference values for RRI were generated according to age. Heritability was estimated by variance components using the ASSOC program (SAGE software). Four hundred women (mean age±SD, 44.9±16.7 years) and 326 men (42.1±16.8 years) with normal renal ultrasound had mean RRI of 0.64±0.05 and 0.62±0.05, respectively ( P <0.001). In multivariable analyses, RRI was positively associated with female sex, age, systolic blood pressure, and body mass index. We observed an inverse correlation with diastolic blood pressure and heart rate. Age had a nonlinear association with RRI. We found no independent association of RRI with diabetes mellitus, hypertension treatment, smoking, cholesterol levels, or estimated glomerular filtration rate. The adjusted heritability estimate was 42±8% ( P <0.001). In a population-based sample with normal renal ultrasound, RRI normal values depend on sex, age, blood pressure, heart rate, and body mass index. The significant heritability of RRI suggests that genes influence this phenotype.

Correlation of ultrasonographic measurement of intrarenal arterial resistance index with microalbuminuria in nonhypertensive, nondiabetic obese patients

PURPOSE

To determine whether intrarenal arterial resistance index (RI) value is related to increased urinary albumin excretion and whether RI value is an independent good indicator to evaluate early renal damage in nonhypertensive, nondiabetic obese subjects.

METHODS

Sixty-four nonhypertensive, nondiabetic obese patients (OB) and 35 age- and sex-matched normal healthy subjects were involved in this study. Clinical characteristics and blood biochemistry of all the subjects were measured. Urinary albumin/creatinine ratio (ACR) and sonographic evaluation of renal blood flow were determined.

RESULTS

ACR and interlobar arterial RI were significantly higher in obese patients than those of normal healthy subjects. Interlobar arterial RI value was higher in patients with microalbuminuria than those with normoalbuminuria. Correlation analysis showed interlobar artery RI value had a positive correlation with ACR (r = 0.615, p < 0.01) and plasma free fatty acids (FFAs, r = 0.407, p < 0.01). ACR had a positive correlation with BMI (r = 0.380, p < 0.01), waist circumference (r = 0.414, p < 0.01), plasma FFAs (r = 0.537, p < 0.01). Multivariate regression analyses showed that ACR was best predicted by interlobar artery RI value even when body mass index, waist circumference, FFAs, and high-sensitive C reaction protein were added in the statistical analysis.

CONCLUSIONS

Interlobar arterial RI may be an independent predictor of microalbuminuria in nonhypertensive, nondiabetic obese patients, and interlobar arterial RI could be a useful tool for assessment early renal damage in obese patients.

Association of renal resistive index with target organ damage in essential hypertension

BACKGROUND

The renal resistive index (RI) measured using Doppler ultrasonography has been used as a diagnostic tool in the daily work-up of kidney diseases. A better understanding of its relationship with preclinical organ damage may help in determining overall cardiovascular risk in hypertensive patients.

METHODS

We evaluated the association between RI and the presence and degree of target organ damage (TOD) in 288 (130 male) essential hypertensive patients. RI, carotid intima-media thickness (IMT), and left ventricular (LV) mass index were assessed by ultrasound scan. Albuminuria was measured as the albumin-to-creatinine ratio (ACR) in three consecutive first morning urine samples.

RESULTS

In univariate analysis, patients with TOD showed significantly higher RI as compared with those without TOD (presence vs. absence of carotid wall thickening, LV hypertrophy, and albuminuria, P < 0.01, respectively). The severity of each TOD increased progressively from the lower to the upper RI tertile. Multiple logistic regression analysis found that each standard deviation increase in RI gave a 47% higher odds of having LV hypertrophy, and a 70% higher odds of having albuminuria (P < 0.05, respectively). The occurrence of at least two signs of TOD also significantly increased in parallel with elevation of RI (odds ratio (OR): 1.89 for 1 s.d. increase, P < 0.01).

CONCLUSIONS

These results suggest that increased RI may be a marker of subclinical TOD in patients with essential hypertension.

Renal arterial resistive index is associated with severe histological changes and poor renal outcome during chronic kidney disease

Background

Chronic kidney disease (CKD) is a growing public health problem and end stage renal disease (ESRD) represents a large human and economic burden. It is important to identify patients at high risk of ESRD. In order to determine whether renal Doppler resistive index (RI) may discriminate those patients, we analyzed whether RI was associated with identified prognosis factors of CKD, in particular histological findings, and with renal outcome.

Methods

RI was measured in the 48 hours before renal biopsy in 58 CKD patients. Clinical and biological data were collected prospectively at inclusion. Arteriosclerosis, interstitial fibrosis and glomerulosclerosis were quantitatively assessed on renal biopsy in a blinded fashion. MDRD eGFR at 18 months was collected for 35 (60%) patients. Renal function decline was defined as a decrease in eGFR from baseline of at least 5 mL/min/ 1.73 m²/year or need for chronic renal replacement therapy. Pearson’s correlation, Mann–Whitney and Chi-square tests were used for analysis of quantitative and qualitative variables respectively. Kaplan Meier analysis was realized to determine renal survival according to RI value using the log-rank test. Multiple logistic regression was performed including variables with p < 0.20 in univariate analysis.

Results

Most patients had glomerulonephritis (82%). Median age was 46 years [21–87], eGFR 59 mL/min/ 1.73m² [5–130], percentage of interstitial fibrosis 10% [0–90], glomerulosclerosis 13% [0–96] and RI 0.63 [0.31-1.00]. RI increased with age (r = 0.435, p = 0.0063), pulse pressure (r = 0.303, p = 0.022), renal atrophy (r = −0.275, p = 0.038) and renal dysfunction (r = −0.402, p = 0.0018). Patients with arterial intima/media ratio ≥ 1 (p = 0.032), interstitial fibrosis > 20% (p = 0.014) and renal function decline (p = 0.0023) had higher RI. Patients with baseline RI ≥ 0.65 had a poorer renal outcome than those with baseline RI < 0.65 (p = 0.0005). In multiple logistic regression, RI≥0.65 was associated with accelerated renal function decline independently of baseline eGFR and proteinuria/creatininuria ratio (OR=13.04 [1.984-85.727], p = 0.0075). Sensitivity, specificity, predictive positive and predictive negative values of RI ≥ 0.65 for renal function decline at 18 months were respectively 77%, 86%, 71% and 82%.

Conclusions

Our results suggest that RI ≥ 0.65 is associated with severe interstitial fibrosis and arteriosclerosis and renal function decline. Thus, RI may contribute to identify patients at high risk of ESRD who may benefit from nephroprotective treatments.

Renal Resistive Index and Cardiovascular and Renal Outcomes in Essential Hypertension

Increased renal restive index (RI) measured using Doppler ultrasonography has been shown to correlate with the degree of renal impairment in hypertensive patients. We investigated the prognostic role of RI in cardiovascular and renal outcomes. A total of 426 essential hypertensive subjects (mean age, 63 years; 50% female) with no previous cardiovascular disease were included in this study. Renal segmental arterial RI was measured by duplex Doppler ultrasonography. During follow-up (mean, 3.1 years), 57 participants developed the primary composite end points including cardiovascular and renal outcomes. In multivariate Cox regression analysis, RI was an independent predictor of worse outcome in total subjects (hazard ratio, 1.71 for 1 SD increase), as well as in patients with estimated glomerular filtration rate (eGFR) <60 mL/min per 1.73 m 2 (hazard ratio, 2.11 for 1 SD increase; P <0.01, respectively). When divided into 4 groups based on the respective sex-specific median levels of RI in the eGFR ≥60 and eGFR <60 mL/min per 1.73 m 2 groups, the group with eGFR <60 and high RI (male ≥0.73, female ≥0.72) had a significantly poorer event-free survival rate (χ 2 =126.4; P <0.01), and the adjusted hazard ratio by multivariate Cox regression analysis was 9.58 (95% CI, 3.26–32.89; P <0.01). In conclusion, impairment of renal hemodynamics evaluated by increased RI is associated with an increased risk of primary composite end points, and the combination of high RI and low eGFR is a powerful predictor of these diseases in essential hypertension. In hypertensive patients with chronic kidney disease, RI evaluation may complement predictors of cardiovascular and renal outcomes.

Carotid resistive index in treated hypertensive patients: relationship with target organ damage

AIM

The resistive index (RI) is a hemodynamic parameter that reflects local wall extensibility and related vascular resistance. We analyze the relationship between common carotid RI and target organ damage in treated hypertensive patients.

METHODS

We analyzed 265 consecutive hypertensive patients. Risk factors, cardiovascular history and treatments were collected; blood test, urinary albumin excretion (UAE), echocardiography to determine left ventricular mass index (LVMI), ankle-brachial index (ABI) and carotid echo-Doppler ultrasound to calculate the carotid intima-media thickness (IMT) and RI of both common carotids arteries were performed.

RESULTS

A positive correlation was found between carotid RI and age, systolic blood pressure, heart rate, carotid IMT, LVMI, UAE and a negative correlation was found with diastolic blood pressure and ABI. Subjects at the top quartile of carotid RI showed a higher prevalence of left ventricular hypertrophy and peripheral artery disease (increased IMT, carotid plaques and lower ABI) compared with those with low RI (p < 0.05). Multiple regression analysis demonstrated that age, systolic and diastolic blood pressure and LVMI independently influence carotid RI.

CONCLUSION

Carotid RI is related with age, systolic-diastolic blood pressure and LVMI in hypertensive patient. This evaluation could predict the presence of early cardiovascular damage and provide an accurate estimation of overall risk in this population.

Are increased carotid artery pulsatility and resistance indexes early signs of vascular abnormalities in young obese males?

PURPOSE

To provide insight into the factors by which obesity in itself may directly lead to early arterial damage, we aimed to determine early sonographic markers of obesity-related vascular dysfunction in young obese males.

METHODS

Thirty-five young obese males and 23 age-matched healthy male volunteers were recruited into the study. Common carotid artery pulsatility index and resistance index were calculated from blood flow velocities curves obtained by pulsed Doppler ultrasonography.

RESULTS

The mean pulsatility index, resistance index, body mass index, waist circumference, systolic and diastolic blood pressure, homeostasis model assessment for insulin resistance, plasma fasting glucose, insulin, C-peptide, triglycerides, low-density lipoprotein cholesterol, and high-sensitivity C-reactive protein were statistically higher in obese subjects than in healthy controls.

CONCLUSIONS

Our results suggest that depressed vessel compliance and increased vascular resistance are features of young, obese, normotensive subjects independently of and in addition to cardiovascular risk factors. As changes in arterial wall properties may be incipient in young obese subjects, future studies will be required to demonstrate whether early intervention such as diet and exercise in this population can improve vascular functions.

Renal hemodynamics and renal function after catheter-based renal sympathetic denervation in patients with resistant hypertension

Increased renal resistive index and urinary albumin excretion are markers of hypertensive end-organ damage and renal vasoconstriction involving increased sympathetic activity. Catheter-based sympathetic renal denervation (RD) offers a new approach to reduce renal sympathetic activity and blood pressure in resistant hypertension. The influence of RD on renal hemodynamics, renal function, and urinary albumin excretion has not been studied. One hundred consecutive patients with resistant hypertension were included in the study; 88 underwent interventional RD and 12 served as controls. Systolic, diastolic, and pulse pressure, as well renal resistive index in interlobar arteries, renal function, and urinary albumin excretion, were measured before and at 3 and 6 months of follow-up. RD reduced systolic, diastolic, and pulse pressure at 3 and 6 months by 22.7/26.6 mm Hg, 7.7/9.7 mm Hg, and 15.1/17.5 mm Hg (P for all <0.001), respectively, without significant changes in the control group. SBP reduction after 6 months correlated with SBP baseline values (r=-0.46; P<0.001). There were no renal artery stenoses, dissections, or aneurysms during 6 months of follow-up. Renal resistive index decreased from 0.691±0.01 at baseline to 0.674±0.01 and 0.670±0.01 (P=0.037/0.017) at 3- and 6-month follow-up. Mean cystatin C glomerular filtration rate and urinary albumin excretion remained unchanged after RD; however, the number of patients with microalbuminuria or macroalbuminuria decreased. RD reduced blood pressure, renal resistive index, and incidence of albuminuria without adversely affecting glomerular filtration rate or renal artery structure within 6 months and appears to be a safe and effective therapeutic approach to lower blood pressure in patients with resistant hypertension.

Relationship between renal hemodynamics and urinary type IV collagen in patients with essential hypertension

Urinary type IV collagen excretion (uT4C) in diabetic patients is higher than in normal subjects. In this study, we investigated the relationship between uT4C and renal hemodynamics in 42 patients with essential hypertension. The renal resistive index (RI) is calculated from blood flow velocities measured using pulsed-wave in interlobar arteries. There was a significant correlation between uT4C to creatinine ratio (uT4C/uCr) and age, hemoglobin A1c (HbA1c), and RI. A stepwise regression analysis showed that RI was independently associated with uT4C/uCr. These results indicated that uT4C may be a marker of renovascular stiffness due to glomerulosclerosis in patients with essential hypertension.

A longitudinal study of the control of renal and uterine hemodynamic changes of pregnancy

We have determined the sequence and extent of maternal renal and uterine adaptation to pregnancy and examined the role of hormonal factors in their regulation. Renal bipolar diameter (RBD), renal artery resistance index (RARI), uterine artery pulsatility index (UAPI), and plasma relaxin, human chorionic gonadotropin (hCG), progesterone, estradiol, urea, and creatinine were measured longitudinally in women with normal spontaneous singleton pregnancies, in vitro fertilization (IVF) singleton pregnancies, ovum donation (OD) singleton pregnancies, and multiple pregnancies from prepregnancy to postpartum. There was a progressive increase in the RBD and the RARI and a decrease in the UAPI during pregnancy. These changes reversed toward prepregnancy levels by 6 weeks post delivery. There was no difference in the rate of change of RBD, RARI, and UAPI between spontaneous singleton, IVF singleton, OD singleton, and multiple pregnancies (p < 0.05), but relaxin was directly correlated to the RARI (r = 0.654, p = 0.015), and progesterone was inversely correlated to uterine artery PI (r = 0.554, p = 0.049). These data show that renal size and resistance to blood flow increase with advancing gestation, whereas the uterine artery resistance declined with gestation. These changes may be influenced by relaxin and progesterone.

Renal resistive index and parathyroid hormone relationship with renal function in nondiabetic patients

INTRODUCTION

The renal resistive index (RRI) reflects intrarenal vascular resistance and stiffness, which are associated with chronic kidney disease. The links connecting renal function, intrarenal arterial resistance, and parathyroid hormone (PTH) with hypertension and metabolic factors remain elusive. The aim of this study is to investigate the possible relationship of RRI with glomerular filtration rate, PTH, hypertension, obesity (body mass index and waist-to-hip ratio), bioelectrical impedance analysis in body composition assessment, serum lipids, and insulin resistance assessed by homoeostasis model insulin resistance index.

PATIENTS AND METHODS

This study was carried out on 387 (246 women, 141 men) nondiabetic patients, between >25 and <75 years, referred to an Internal Medicine Clinic and Day Hospital for essential hypertension, overweightness-obesity, and/or dyslipidemia. Lower salt/lower calorie Mediterranean diet, physical activity increase, smoking withdrawal, and lifestyle counseling, provided by a health psychologist support, were prescribed.

RESULTS

Higher hypertension risk, present in 42.5% of the overall group of eligible patients (164/387), is associated with high PTH and high RRI, along with greater renal insufficiency, insulin resistance, and obesity. There is a straight linear relationship of RRI to PTH (0.202; p=0.009) in arterial hypertension, which is not observed in normal blood pressure patients. By gender-adjusted multiple linear regression analysis, it was found that fat mass, waist-to-hip ratio, and PTH account significantly for 62.3% of the variance to RRI in hypertensive patients.

CONCLUSION

Increased arterial stiffness and intrarenal arterial resistance are associated with higher PTH in arterial hypertension; obesity (defined by greater fat mass and waist-to-hip ratio) and PTH are the independent conditions that account significantly for higher RRI.

Renal resistive index and low-grade inflammation in patients with essential hypertension

In essential hypertension, increased renal resistive index (RRI) is associated to a reduction of renal function and microalbuminuria, and to renal tubulo-interstitial damage. A tubulo-interstitial inflammatory infiltration was found in experimental models of hypertension, and serum high-sensitive C-reactive protein (hsCRP) levels correlated with urinary markers of tubulo-interstitial damage in humans. We studied the relationship between RRI and serum hsCRP in hypertensives with preserved renal function, without microalbuminuria. We investigated hypertensive patients without diabetes, renal failure, microalbuminuria or major inflammatory disease. Serum levels of hsCRP were assayed. RRI was calculated by intrarenal Doppler ultrasound and considered pathologic when ≥0.70 or >95% of upper confidence limit expected for age decade. The renal volume-to-resistive index ratio (RV/RRI) was also calculated. We evaluated 85 patients (57±14 years, 61 males). Patients with pathologic RRI (n=21) were older and had significantly higher hsCRP levels (4.70±2.30 vs 2.93±2.09 mg l(-1), P<0.01) compared with patients with normal RRI, as well as patients with decreased RV/RRI (n=43). HsCRP was directly related with RRI (r=0.41, P<0.001) and inversely with RV/RRI (r=-0.35, P<0.001). HsCRP proved to be a significant predictor of both pathologic RRI and decreased RV/RRI, even after adjustment. In essential hypertension low-grade inflammation is associated with tubulo-interstitial damage evaluated by Doppler ultrasonography.

Central pulse pressure and aortic stiffness determine renal hemodynamics: pathophysiological implication for microalbuminuria in hypertension

A significant link has been reported between aortic stiffening and renal microvascular damage, but the underlying mechanism remains poorly understood. We hypothesized that alterations in central and renal hemodynamics are responsible for this link. In 133 patients with hypertension, pressure waveforms were recorded on the radial, carotid, femoral, and dorsalis pedis arteries with applanation tonometry to estimate the aortic pressures and aortic (carotid-femoral) and peripheral (carotid-radial and femoral-dorsalis pedis) pulse wave velocities. Flow-velocity waveforms were recorded on the renal segmental arteries with duplex ultrasound to calculate the resistive index (RI) as [1 - (end-diastolic velocity/peak systolic velocity)] and on the femoral arteries to calculate the reverse/forward flow index and diastolic/systolic forward-flow ratio. Albuminuria was defined as urinary albumin/creatinine ratio ≥30 mg/g of creatinine. The renal RI (mean: 0.65±0.07) was strongly correlated (P<0.001) with the aortic pulse pressure (r=0.62), incident pressure wave (r=0.55), augmented pressure (r=0.49), and aortic pulse wave velocity (r=0.51), although not with the mean arterial pressure or peripheral pulse wave velocities. The correlations remained highly significant after consideration of confounders including age, cholesterol, hemoglobin A(1c), and glomerular filtration rate. The renal RI was inversely correlated with the femoral reverse and diastolic forward flow indices. Both aortic pulse pressure and renal RI correlated with the urinary albumin/creatinine ratio independent of confounders. Each 0.1 increase in renal RI was associated with a 5.4-fold increase in the adjusted relative risk of albuminuria. In conclusion, increased aortic pulse pressure causes renal microvascular damage through altered renal hemodynamics resulting from increased peripheral resistance and/or increased flow pulsation.

Dynamic evaluation of renal resistive index in normoalbuminuric patients with newly diagnosed hypertension or type 2 diabetes

AIM/HYPOTHESIS

Renal resistive index is a useful measure for quantifying alterations in renal blood flow. In the present study we evaluated resistive index at baseline and after vasodilation induced by nitroglycerine in normoalbuminuric patients with type 2 diabetes or essential hypertension, relating the values to indices of systemic vascular dysfunction.

METHODS

Newly diagnosed treatment-naïve type 2 diabetic (n = 32) and hypertensive patients (n = 49) were compared with 27 age- and sex-matched healthy controls. Renal resistive index was obtained by duplex ultrasound at baseline and after 25 μg sublingual nitroglycerine. Endothelium-dependent (flow-mediated dilation) and -independent (response to nitroglycerine) vasodilation in the brachial artery was assessed by computerised edge detection system. Carotid-femoral pulse-wave velocity and augmentation index were assessed by applanation tonometry. Nitrotyrosine levels, an index of oxidative stress, were also measured.

RESULTS

Resistive index was higher in diabetic than in hypertensive patients and controls (p < 0.001), while changes in resistive index induced by nitroglycerine were lower in hypertensive patients compared with controls (p < 0.01), and were further reduced in type 2 diabetic patients. Hypertensive and diabetic patients showed significantly increased arterial stiffness, nitrotyrosine levels and reduced endothelial function than controls (p < 0.05). Changes in resistive index induced by nitroglycerine were independently related to serum glucose, reactive hyperaemia and aortic pulse-wave velocity in the overall population.

CONCLUSIONS/INTERPRETATION

These results support the dynamic evaluation of renal resistive index as an early detector of renal vascular alterations in the presence of type 2 diabetes and hypertension, even before the onset of microalbuminuria.

Common carotid end-diastolic velocity and intima-media thickness jointly predict ischemic stroke in Taiwan

BACKGROUND AND PURPOSE

In Asian populations, few studies investigated the association between stroke and common carotid artery intima-media thickness (IMT). Our previous case-control studies showed that low end-diastolic velocity (EDV) in common carotid artery, a potential hemodynamic marker of intracranial resistance, was associated with ischemic stroke. Therefore, we investigated the relationship between both EDV and IMT and incident ischemic stroke in an Asian population.

METHODS

Baseline data from 3175 adults (30 years or older) in the Cardiovascular Diseases Risk Factor Two-Township Study were linked to incidental ischemic stroke status derived from insurance claims and death certificate records. Hazard ratios for risk of ischemic stroke for high IMT and low EDV values measured in common carotid artery were calculated using Cox proportional hazard models.

RESULTS

With 9.85 years (median) of follow-up, 184 persons had ischemic stroke develop. Compared with the first tertile of IMT, hazard ratios were 2.03 (95% confidence intervals, 1.27-3.25) for the second tertile and 3.87 (95% confidence intervals, 2.36-5.69) for the third tertile. Hazard ratios of EDV were 5.31 (95% confidence intervals, 3.52-7.99; first tertile) and 1.94 (95% confidence intervals, 1.21-3.09; second tertile) compared with the third tertile. The individuals with high IMT and low EDV had >2-fold ischemic stroke risk compared to those with low IMT and high EDV (2.10; 95% confidence intervals, 1.35-3.26) after adjusting for age, sex, and traditional cardiovascular risk.

CONCLUSIONS

Common carotid IMT and EDV jointly and independently predicted future ischemic stroke in this Taiwanese population. More prospective studies are required in various ethnic groups to understand the significance and implication of the current findings, particularly with respect to EDV.

Renal function and severity of bright liver. Relationship with insulin resistance, intrarenal resistive index, and glomerular filtration rate

AIMS

Relationships of renal function and liver disease are described in acute and chronic liver failure. The aim of the study is to investigate which relationship, if any, is present between severity of non-alcoholic fatty liver disease (NAFLD), assessed by bright liver score (BLS) versus mild-moderate renal insufficiency assessed by glomerular filtration rate (GFR) and by ultrasound intra-renal arterial resistive index (RRI). Moreover, which difference, if any, can be found in NAFLD patients with normal versus increased transaminases.

PATIENTS

The study enrolled 323 NAFLD and 176 non-NAFLD consecutive patients, comparable for age, gender distribution, GFR, and RRI referred to a university clinical day hospital after an ultrasound diagnosis of bright liver, for clinical-nutritional counselling. Personalized computerized mediterranean diet, physical activity increase, and smoking withdrawal integrated counselling were provided.

RESULTS

In NAFLD patients, homoeostasis model (HOMA) has a significant correlation with BLS. According to the severity of BLS, grade II-III versus grade I patients have significantly higher values of HOMA, body mass index (BMI), triglycerides, and longitudinal right liver length. By odds ratio, more severe BLS, increased HOMA, and transaminases are associated with lower GFR. Increased transaminases are associated with higher grades of BLS, HOMA, and BMI. By multiple linear regression waist-to-hip ratio, RRI, and BLS, as significant independent factors (p < 0.0001), explain significantly variance to GFR. This is not observed in normal control group, in which only RRI is a factor explaining GFR.

CONCLUSION

Greater RRI, abdominal obesity, and greater BLS account for a lower GFR in NAFLD patients suggesting the hypothesis that inter-related factors can be operating early in the natural history of obesity-related kidney and liver disease.

Impairment of skin blood flow during post-occlusive reactive hyperhemy assessed by laser Doppler flowmetry correlates with renal resistive index

We lack non-invasive tools for evaluating the coronary and renal microcirculations. Since cutaneous Doppler laser exploration has evidenced impaired cutaneous microvascular responses in coronary artery disease and in impaired renal function, we wanted to find out if there was a link between the impairments in the cutaneous and renal microcirculations. To specify the significance of the rise in the renal resistive index (RI), which is still unclear, we also sought relations between RI and arterial stiffness. We conducted a cross-sectional controlled study in a heterogeneous population including hypertensive patients of various ages with or without a history of cardiovascular disease along with a healthy control group. The cutaneous microcirculation was evaluated by laser Doppler flowmetry of the post-occlusive reactive hyperhemy (PORH) and of the hyperhemy to heat. The renal microcirculation was evaluated by measurement of the RI. Arterial stiffness was evaluated from an ambulatory measurement of the corrected QKD(100-60) interval. We included 22 hypertensives and 11 controls of mean age 60.6 vs 40.8 years. In this population, there was a correlation between RI and basal zero to peak flow variation (BZ-PF) (r=-0.42; P=0.02) and a correlation between RI and rest flow to peak flow variation (RF-PF) (r=-0.44; P=0.01). There was also a significant correlation between RI and the corrected QKD(100-60) (r=-0.47; P=0.01). The significant correlation between PORH parameters and RI indicates that the functional modifications of the renal and cutaneous microcirculations tend to evolve in parallel during ageing or hypertension. The relation between RI and arterial stiffness shows that RI is a compound index of both renal microvascular impairment and the deterioration of macrovascular mechanics.

Lifestyle interventions, insulin resistance, and renal artery stiffness in essential hypertension

The study investigates lifestyle and effective anti-hypertensive intervention in overweight-obese patients can influence insulin-resistance (HOMA-IR) and US Renal-Resistive-Index (RRI). After a 1-year interventional program (including a personalized Mediterranean diet, physical activity increase, smoking withdrawal counseling), 156 Essential Hypertension (EH) patients still have abnormal HOMA-IR, significantly higher in comparison to 159 control group patients. Body mass index (BMI) and cholesterol-high-density-lipoprotein improvement are the best predictors of a HOMA-IR decrease; RRI improves in EH according to lifestyle interventions, but no predictor to RRI is identified. Persistence of IR can be tentatively assumed as a steady sign, persistent also after extended lifestyle intervention in EH, further warranting more intensive dietary interventions.

Renal vascular response to angiotensin II inhibition in intensive antihypertensive treatment of essential hypertension

INTRODUCTION

High blood pressure (BP) leads to target organ damage. It is suggested that regression of early organ lesions is possible on condition of BP normalization. The study objective was to assess whether permanent reduction of BP to the recommended values modifies renal vascular response to acute angiotensin II inhibition in the Doppler captopril test (DCT) in patients with essential hypertension (EH).

MATERIAL AND METHODS

Twenty-nine persons (58 kidneys) were found eligible for the study: 18 patients with EH and 11 healthy volunteers constituting the control group. Glomerular filtration rate estimation (eGFR), 24-h ambulatory BP monitoring (ABPM) and DCT with evaluation of renal resistive index change (ΔRI) were performed before and after a 6-month period of intensive antihypertensive therapy (IAT). Additional ABPM was performed at the end of IAT.

RESULTS

The mean IAT period was 8.5 ±2.4 months. The mean 24-h values of systolic and diastolic BP in the EH group were significantly lower in the IAT period than at the beginning and at the end of the study. Significantly lower systolic and diastolic BP (p < 0.05) and improvement of renal function (eGFR 121 ±38 vs. 139 ±40 ml/min, p < 0.001) were found after IAT as compared to initial values. Before IAT, ΔRI was significantly lower in the EH group as compared to the controls, but no such differences were found after IAT.

CONCLUSIONS

In EH patients, intensive BP lowering to the recommended values was associated with improvement of renal function and normalisation of renal vascular response to acute angiotensin II inhibition.

The renal resistance index is increased in mild-to-moderate obstructive sleep apnoea and is reduced under continuous positive airway pressure

BACKGROUND

Impaired renal function has recently been reported in obstructive sleep apnoea (OSA). The underlying mechanisms, however, are not entirely understood. This study investigated the influence of mild-to-moderate OSA and its treatment on renal haemodynamics as assessed by the renal resistance index (RRI).

METHODS

RRI has been measured by colour duplex ultrasound in 64 patients with newly diagnosed mild-to-moderate OSA and 61 controls without OSA at baseline and follow-up after 9.9 months. Treatment with continuous positive airway pressure was offered to all patients with OSA (apnoea/hypopnoea index ≥ 5/h).

RESULTS

Increased values of RRI (≥ 1 SD [8.9%] above the age-adjusted normal value) were found in 41 out of 64 (64.0%) OSA patients when compared with 20 out of 61 (32.8%) controls (P < 0.001). The corresponding mean RRI was 70.50 ± 9.01 vs 66.51 ± 8.33 (P = 0.012). In multivariate analyses, the influence of OSA on RRI was independent from hypertension, diabetes mellitus, age and baseline renal function. At follow-up, RRI decreased only in patients with effective OSA treatment but remained unchanged in ineffectively treated OSA patients and controls.

CONCLUSIONS

For the first time, this prospective controlled observational study demonstrates an impairment of renal haemodynamics in OSA as measured by an increased RRI. These changes of renal blood flow may identify OSA patients at high risk of declining renal function. Both parenchymal and vascular renal diseases are proposed as pathomechanisms for this association. An effective treatment of OSA resulted in a decreased RRI, suggesting an improvement in renal perfusion. Further studies are needed to elucidate the role of impaired renal haemodynamics in OSA.

Serum uric acid levels and renal damage in hyperuricemic hypertensive patients treated with renin-angiotensin system blockers

BACKGROUND

A correlation between hyperuricemia and renal target organ damage (TOD) was shown in hypertensive patients, locally mediated by the activation of renin-angiotensin system (RAS). We investigated whether high serum uric acid (UA) levels could negatively affect tubulointerstitial damage in hyperuricemic essential hypertensive patients with normal renal function, on treatment with RAS-blocking drugs.

METHODS

We studied 40 patients with World Health Organization stage I-II essential hypertension, 9 with high serum UA levels (hyperuricemic group) and 31 with normal serum UA levels (normouricemic group, either normouricemics, n = 15, or formerly hyperuricemics in chronic allopurinol treatment, n = 16). All patients were on RAS-blocking drugs (either angiotensin-converting enzyme inhibitors or angiotensin II receptors blockers). Evaluation of renal TOD included urinary albumin excretion (UAE), Doppler ultrasound renal resistive index (RRI) and renal volume-to-resistive index ratio (RV/RRI) measurements.

RESULTS

Hyperuricemics had significantly higher RRI and lower RV/RRI values than normouricemics. Creatinine clearance and UAE were similar between groups. Linear regression analysis showed that RV/RRI values were inversely related to serum UA levels (r = -0.57, P < 0.01). The logistic regression analysis selected serum UA as an independent predictor of decreased RV/RRI (odds ratio 4.45, 95% CI 1.47-13.45, P = 0.01).

CONCLUSIONS

In hyperuricemic hypertensives normal serum UA levels are associated with normal RV/RRI, integrated marker of tubulointerstitial damage and renal arteriolopathy, independently of RAS activation.

Relationship between renal resistive index and inflammation in untreated hypertensive patients

The aim of this study was to evaluate the relationship between renal resistive index and inflammation in untreated hypertensive patients. Sixty-one hypertensive patients (male/female: 38/23, aged 45.8 +/- 8.3 years, and mean hypertension duration 28.2 +/- 35.6 months) and 40 (male/female: 23/17, aged 42.7 +/- 8.5 years) healthy control subjects were included in the study. Renal resistive index was positively correlated with age (P = 0.016, r = 0.308), pulse pressure (P = 0.022, r = 0.294), C-reactive protein (P = 0.00, r = 0.757), urinary albumin excretion (P = 0.003, r = 0.371) and negatively correlated with creatinine clearance (P = 0.042, r = -0.262) in the hypertensive group. The hypertensive group was further divided in two groups according to the renal resistive index; < 0.60 and > 0.60. In the > 0.60 group, age (48.0 +/- 7.3 versus 42.8 +/- 8.9 years, P = 0.01) and C-reactive protein levels (7.4 +/- 1.5 versus 4.0 +/- 1.6 mg/L, P = 0.01) were higher, and creatinine clearance (95.5 +/- 22.1 versus 109.1 +/- 25.3 mL/min, P = 0.04) was lower than the < 0.60 group. Renal resistive index was higher in the nondippers than the dippers (0.61 +/- 0.04 versus 0.58 +/- 0.03, P = 0.003). Renal resistive index is associated with inflammation and may be a useful marker, together with albuminuria, in hypertensive patients when evaluating hypertensive renal damage.

Renal resistive index--a valid tool to assess renal endothelial function in humans?

BACKGROUND

In humans, renal endothelial function is assessed by the vasoconstrictive response to L-NG-monomethyl arginine (L-NMMA). We hypothesized that Doppler sonographic measurements of the renal resistive index in response to inhibition of nitric oxide synthase offer a new methodological approach for testing renal endothelial function.

METHODS

Forty-one patients without nephropathy were included. Para-aminohippurate and inulin clearance were performed under basal conditions and during L-NMMA infusion. In parallel, renal resistive index was assessed by Doppler sonography, and central blood pressure was determined.

RESULTS

Following nitric oxide synthase inhibition, renal resistive index increased significantly, and 29% of our patients developed Doppler sonographic diastolic zero flow. Renal plasma flow decreased in response to L-NMMA, and conversely, renal vascular resistance increased. There was no correlation of renal vascular resistance and renal resistive index at baseline and during nitric oxide synthase inhibition. Changes in renal resistive index were not related to changes in renal perfusion or renal vascular resistance. Renal resistive index correlated with central pulse pressure at baseline and during L-NMMA infusion, whereas renal vascular resistance did not correlate with central pulse pressure.

CONCLUSION

Our data do not support the hypothesis that renal resistive index is a tool to test renal endothelial function in humans and should not be used interchangeably with renal vascular resistance.

Insulin resistance is associated with increased renal resistive index independent of other factors in newly diagnosed type 2 diabetes mellitus and hypertensive patients

Renal resistive index (RRI) is increased in subjects with diabetes. We analyzed whether insulin resistance is independently related with RRI. Medical history, physical examination, laboratory analysis, Doppler ultrasonography, and 24-hour urinary albumin excretion were analyzed. The threshold for an increased RRI was at least 0.70, which has been previously shown to be discriminatory of increased RRI level. Eighty newly diagnosed essential hypertensive and type 2 diabetes mellitus patients were included. Sixty-one patients had low RRI (<0.70). When compared with low-RRI patients, those with high RRI were older and had higher pulse pressure, serum creatinine, and homeostasis model assessment (HOMA) index. The HOMA index and RRI were positively correlated (r = +0.371, P = .001). In multivariate logistic regression analysis, age (odds ratio [OR] = 1.164, 95% confidence interval [CI] = 1.040-1.303, P = .008), pulse pressure (OR = 1.188, 95% CI = 1.020-1.384, P = .027), and HOMA index (OR = 1.422, 95% CI = 1.085-1.862, P = .011) were independently associated with high RRI. Increased insulin resistance is independently related with increased RRI.

Evaluation of renal volume by ultrasonography in patients with essential hypertension in Ile-Ife, south western Nigeria

Background and aims

To determine renal volume in adult patients with essential hypertension and correlate it with age, sex, body mass index (BMI), body surface area (BSA) and duration of hypertension.

Patients and methods

A total of 150 patients (75 males, 75 females) with essential hypertension and normal renal status were evaluated sonographically in this prospective study. Fifty healthy individuals (25 males, 25 females) without hypertension were also evaluated as control. Renal volume was then calculated from the kidney's length, width and anterio-posterior diameter using the formula L×W×AP×0.523.

Results

The range of renal volume obtained was 51.65–205.02 cm³, with a mean of 114.06 ± 29.78 cm³ for the left kidney and 47.37–177.50 cm³ with a mean of 106.14 ± 25.42 cm³ for the right kidney. The mean volumes of the right and left kidneys in males (112.98 ± 25.56 cm³ and 123.11 ± 32.49 cm³, respectively), were significantly higher than in females (99.31 ± 23.07 cm³ and 105.01 ± 23.77 cm³, respectively). Renal volume correlated significantly with BSA and BMI, but decreased with age. The renal volume showed no correlation with duration of hypertension.

Conclusion

Renal volume is higher in the left than the right kidney in hypertensive patients of both sexes and female hypertensive patients have smaller kidney size compared to males. The study also shows that volume of both kidneys decreases with age and positive correlation between renal volume, BSA and BMI. However, there is no correlation between renal size and duration of hypertension.

Relationship between serum homocysteine and other parameters in renal transplant patients

INTRODUCTION

Hyperhomocysteinemia frequently occurs after renal transplantation. We therefore assessed whether serum homocysteine (Hcy) concentrations were correlated with clinical, paraclinical, and arterial Doppler parameters among renal transplant patients.

METHODS

A cross-sectional study was performed on 47 patients (30 males, 17 females) who received unrelated living donor renal transplants.

RESULTS

The mean serum Hcy concentration was 21.7 +/- 8.4 micromol/L (range = 5.8-48 micromol/L); 37 patients (79%) showed hyperhomocysteinemia (Hcy >or= 15 micromol/L). Serum Hcy was strongly related to body mass index (BMI; r = .43, P = .002), cyclosporine trough level (r = .44, P = .005), and serum creatinine concentration (r = .32, P = .028), but not to age, transplant duration, or sex. Multivariate analysis showed that only BMI (P = .003) and cyclosporine trough level (P = .0037) were independent predictors of serum Hcy concentrations. Hyperhomocysteinemia was more prevalent among patients taking mycophenolate mofetil (MMF) than azathioprine (86% vs 50%; P = 0.017). The hyperhomocysteinemia and normohomocysteinemia groups did not differ significantly in mean carotid intima-media thickness (IMT; 0.78 +/- 0.348 vs 0.77 +/- 0.419 mm, P = .97) or mean intrarenal resistive index (RI) (0.7 +/- 0.06 vs 0.7 +/- 0.06, P = .85). The two groups also did not differ in sex prevalence, diabetes, C-reactive protein >or= 5 mg/L, or mean low-density lipoprotein, high-density lipoprotein, and mean arterial pressure (MAP) values.

CONCLUSION

Serum Hcy correlated with higher cyclosporine trough levels and obesity. Hyperhomocysteinemia was more common among patients taking MMF than azathioprine, but had no effect on intrarenal RI or carotid IMT.

Intra-renal hemodynamics and carotid intima-media thickness in the metabolic syndrome

AIMS

Metabolic syndrome (MetS) is associated with increased cardiovascular risk. We hypothesize that early vascular changes are already present at the time of diagnosis of MetS. The relationship of different measures of early vascular impairment with body fat distribution and the natural progression of MetS was examined in newly diagnosed subjects non-pharmacologically treated.

METHODS

246 consecutively enrolled subjects were categorized according to the presence of MetS and type 2 diabetes (T2D). Intra-renal Doppler flow was used to ascertain resistive (RI) and pulsatility (PI) indices as markers of vascular resistance. Carotid intima-media thickness (IMT), cutis-rectis (CR) and rectis-aorta (RA) thicknesses were measured by ultrasonography; RA/CR ratio was used as measure of body fat distribution. Pro-inflammatory cytokines, C-reactive protein, oxidative markers insulin and adiponectin blood concentrations were also measured.

RESULTS

Baseline characteristics demonstrated increasing trends in biochemical, inflammatory, and oxidative parameters from MetS-, MetS+, to MetS+/T2D (p<0.001). After adjusting for age, the same increasing trends across the groups were observed in both sexes in IMT (p<0.001), RI (p<0.001) and PI (p<0.001). IMT correlated with RI (r=0.25; p<0.001), PI (r=0.26; p<0.001), and RA/CR ratio (r=0.43; p<0.001).

CONCLUSIONS

Carotid IMT and intra-renal resistances are elevated at an early stage in MetS and are associated with a dysregulated production of fat-derived hormones and cytokines.

Relationship between renal resistive index and early target organ damage in patients with never-treated essential hypertension

The aim of our study was to evaluate renal resistive index (RI) value in never treated hypertensive patients in relation to ambulatory blood pressure measurement (ABPM) values and early target organ damage. The study included 318 subjects: 223 patients with never treated essential hypertension (mean age 37.1 years) and 95 normotensive healthy subjects (mean age 37.9 years). ABPM, echocardiography and carotid and renal arteries duplex color Doppler examinations were performed. RI values in patients with never treated essential hypertension were no different from the normotensive control group (0.59 +/- 0.05 vs 0.59 +/- 0.05; NS). In the untreated patients RI correlated significantly with 24-h pulse pressure (r=0.234; p<0.01) and ambulatory arterial stiffness index (AASI) values (r=0.274; p<0.001), intima-media thickness (IMT) (r=0.249; p<0.001), E'/A' (rho= -0.279; p<0.001) and relative wall thickness (RWT; r=0.185; p<0.01). In the multivariate stepwise analysis, RI values correlated independently with carotid IMT (beta=0.272; p=0.020) and 24-h AASI values (beta=0.305; p=0.009). In normotensive healthy controls, significant independent correlation between RI and carotid IMT and 24-h AASI values were also found. Our study may indicate limited value of RI in differentiating patients with uncomplicated hypertension with healthy controls. Renal resistive values were independently correlated with carotid IMT and AASI. These may suggest that renal vascular resistance is related to two markers for cardiovascular events both in the hypertensive and normotensive subjects.

Valsartan Reduces Serum Cystatin C and the Renal Vascular Resistance in Patients with Essential Hypertension

A high level of albuminuria and increased renal vascular resistance are associated with hypertensive renal damage. In this study, the authors investigated the effect of the angiotensin II receptor blocker, valsartan, on renal function and intrarenal hemodynamics in non-diabetic patients with essential hypertension. A prospective three-month study of the effects of valsartan, 40-80 mg/day, was performed in 30 hypertensive patients. As an assessment of renal function, serum creatinine, urine albumin/creatinine (Alb/Cr) ratio, and serum cystatin C levels were evaluated. Doppler ultrasonography of the kidney was performed for the evaluation of renal hemodynamics. Peak-systolic, end-diastolic, and mean velocities of interlobar arteries were evaluated, and the pulsatility index (PI) and resistive index (RI) were calculated. It was determined that patients with microalbuminuria had higher levels of serum cystatin C, PI, and RI compared to patients without microalbuminuria. Valsartan treatment significantly reduced systolic and diastolic blood pressure and decreased the Alb/Cr ratio. Serum creatinine was not changed, whereas serum cystatin C levels were significantly reduced. Valsartan treatment significantly decreased the PI in all patients and both PI and RI in patients with microalbuminuria. These results suggest that the angiotensin II receptor blocker, valsartan, is able to improve renal function by reducing renal vascular resistance in hypertensive patients, especially in patients with microalbuminuria, and may prevent future renal failure in patients with essential hypertension.