Renal resistive index and cardiovascular and renal outcomes in essential hypertension

Resistive index as predictor of acute kidney injury in patients with non-ST-segment elevation myocardial infarction

BACKGROUND

Acute kidney injury (AKI) is common in patients with non-ST-segment elevation myocardial infarction (NSTEMI). Early detection of AKI is likely to speed diagnosis and implementation of measures to preserve renal function. To evaluate if renal Doppler resistive index (RI) would predict AKI in patients with NSTEMI on presentation in the emergency department.

METHODS

Patients with NSTEMI at the emergency department were included. The renal Doppler RI was measured. Baseline demographic data and clinical characteristics of patients at admittance were recorded. Based on discharge diagnosis, the patients were divided into AKI group and no-AKI group. Multiple logistic regression analysis was performed to determine predictor variables significantly associated with AKI.

RESULTS

A total of 293 patients were included in the analysis; 44 (15.0%) developed AKI without need for dialysis. There were statistical differences in the age, incidence of diabetes mellitus and cerebrovascular disease, beta-receptor blockers, serum creatinine and renal index between the two groups. Using multivariate logistic regression analysis, age [OR 1.87; 95% confidence interval (CI) 1.595-2.585; p = 0.027], diabetes mellitus (OR 2.007, 95% CI: 1.489-2.793; p = 0.014), serum creatinine (OR 1.817, 95% CI: 1.568-2.319; p = 0.013), and RI (OR 2.168, 95% CI: 1.994-4.019; p = 0.003) predicted AKI in patients with NSTEMI. According to receiver operating characteristic (ROC) analysis, RI showed a significantly increased area under the curve (AUC) compared to serum creatitine (AUC: 0.891 vs 0.679; p < 0.001).

CONCLUSIONS

Renal Doppler RI may be a useful predictor of AKI in patients with NSTEMI in the emergency department.

Fructose plus High-Salt Diet in Early Life Results in Salt-Sensitive Cardiovascular Changes in Mature Male Sprague Dawley Rats

Fructose and salt intake remain high, particularly in adolescents and young adults. The present studies were designed to evaluate the impact of high fructose and/or salt during pre- and early adolescence on salt sensitivity, blood pressure, arterial compliance, and left ventricular (LV) function in maturity. Male 5-week-old Sprague Dawley rats were studied over three 3-week phases (Phases I, II, and III). Two reference groups received either 20% glucose + 0.4% NaCl (GCS-GCS) or 20% fructose + 4% NaCl (FHS-FHS) throughout this study. The two test groups ingested fructose + 0.4% NaCl (FCS) or FHS during Phase I, then GCS in Phase II, and were then challenged with 20% glucose + 4% NaCl (GHS) in Phase III: FCS-GHS and FHS-GHS, respectively. Compared with GCS-GCS, systolic and mean pressures were significantly higher at the end of Phase III in all groups fed fructose during Phase I. Aortic pulse wave velocity (PWV) was elevated at the end of Phase I in FHS-GHS and FHS-FHS (vs. GCS-GCS). At the end of Phase III, PWV and renal resistive index were higher in FHS-GHS and FHS-FHS vs. GCS-GCS. Diastolic, but not systolic, LV function was impaired in the FHS-GHS and FHS-FHS but not FCS-FHS rats. Consumption of 20% fructose by male rats during adolescence results in salt-sensitive hypertension in maturity. When ingested with a high-salt diet during this early plastic phase, dietary fructose also predisposes to vascular stiffening and LV diastolic dysfunction in later life.

Cystatin C, vascular biomarkers and measured glomerular filtration rate in patients with unresponsive hypertensive phenotype: a pilot study

Background: Biomarkers are commonly used to estimate the presence of subclinical cardiovascular disease (CVD) in patients with essential arterial hypertension (HT). In addition to known association between cystatin C and glomerular filtration rate (GFR), elucidating the association between cystatin C and vascular biomarkers (intima-media thickness of common carotid arteries (CCIMT), carotid plaque and renal artery resistance index (RRI)) in patients with unresponsive hypertensive phenotype could be of significant clinical interest.

Methods: Participants (n = 200, median age 58 (52–64) years, 49% female) under treatment with antihypertensive drugs were stratified into two subgroups based on their blood pressure level as having responsive hypertension (RHT – compliant and responsive to treatment, n = 100), or nonresponsive (URHT – compliant but nonresponsive to treatment, n = 100). GFR was measured by isotopic (slope-intercept) method (99m Tc diethylene triamine penta-acetic acid – mGFR).

Results: The URHT group had significantly higher median cystatin C serum concentration (p = 0.02) and CCIMT (p = 0.00) compared to the RHT group, with no significant difference in RRI (p = 0.51) and mGFR among subgroups [69.9 ± 28.2 vs 76.74 ± 23.61 ml/min/1.73m², p = 0.27]. In the URHT group, cystatin C was found to be associated with CCIMT (p = 0.02), hsCRP (p = 0.01) and duration of HT (p = 0.02), independently of mGFR and age. Independent predictors of URHT phenotype were CCIMT (p= 0.02) and hsCRP (p= 0.04).

Conclusion: In addition to GFR, cystatin C serum concentration is positively and independently associated with CCIMT in patient with URHT phenotype and subclinical CVD. Prospective larger studies should further investigate the clinical importance of this relationship.

Renal resistive index and mortality in chronic kidney disease

Renal resistive index (RRI) measured by Doppler ultrasonography is associated with cardiovascular events and mortality in hypertensive, diabetic, and elderly patients. We studied the factors associated with high RRI (≥0.70) and its associations with mortality in chronic kidney disease patients without renal artery stenosis. We included 1962 patients with an estimated glomerular filtration rate of 15 to 59 mL/min per 1.73 m(2) who also had RRI measured (January 1, 2005, to October 2011) from an existing chronic kidney disease registry. Participants with renal artery stenosis (60%-99% or renal artery occlusion) were excluded. Multivariable logistic regression model was used to study factors associated with high RRI (≥0.70), and its association with mortality was studied using Kaplan-Meier plots and Cox proportional hazards model. Hypertension was prevalent in >90% of the patients. In the multivariable logistic regression, older age, female sex, diabetes mellitus, coronary artery disease, peripheral vascular disease, higher systolic blood pressure, and the use of β blockers were associated with higher odds of having RRI≥0.70. During a median follow-up of 2.2 years, 428 patients died. After adjusting for covariates, RRI≥0.70 was associated with increased mortality (adjusted hazard ratio, 1.29; 95% confidence interval, 1.02-1.65; P<0.05). This association was more pronounced among younger patients and those with stage 3 chronic kidney disease. Noncardiovascular/non-malignancy-related deaths were higher in those with RRI≥0.70. RRI≥0.70 is associated with higher mortality in hypertensive chronic kidney disease patients without clinically significant renal artery stenosis after accounting for other significant risk factors. Its evaluation may allow early identification of those who are at risk thereby potentially preventing or delaying adverse outcomes.

Renal resistive index as a marker of vascular damage in cardiovascular diseases

The article presents changeability of renal resistive index (RRI) in various cardiovascular diseases and considers the usefulness of the marker and interpretational difficulties of the index. The values of RRI are not specific to an individual disease, but in a selected group of patients, it seems to be a perfect marker of cardiovasculorenal changes and a predictor of rapid loss of a renal function. The RRI usually does not reflect the vascular resistance, but is dependent on total and local vascular bed compliance changing with age, in the course of consecutive diseases and the influence of drugs. Under specific conditions, RRI appears to be a good marker of vascular damage. This review summarizes current concepts in RRI interpretation against the cardiovascular pathologies, focusing on the vascular damage association with regard to the complex nature of RRI value variability.