Prevalence and outcome of renal artery stenosis in atherosclerotic patients with renal dysfunction

Correlation and risk factors of peripheral and cervicocephalic arterial atherosclerosis in patients with ischemic cerebrovascular disease

Patients with ischemic cerebrovascular disease (ICVD) frequently develop concomitant peripheral artery disease (PAD) or renal artery stenosis (RAS), and multiterritorial atherosclerotic patients usually have a worse prognosis. We aimed to evaluate the status of peripheral atherosclerosis (AS) and cervicocephalic AS (CAS) in ICVD patients with AS, their correlation, and related risk factors contributing to coexisting cervicocephalic-peripheral AS (CPAS). Based on the severity and extent of AS evaluated by computed tomography angiography and ultrasound, the degree of AS was triple categorized to assess the correlation between CAS and PAD/RAS. CAS and PAD/RAS were defined as the most severe stenosis being ≥ 50% luminal diameter in cervicocephalic or lower limb arteries, and a peak systolic velocity at the turbulent site being ≥ 180 cm/s in the renal artery. Among 403 patients with symptom onset within 30 days, CAS, PAD, and RAS occurrence rates were 68.7%, 25.3%, and 9.9%, respectively. PAD was independently associated with the degree of extracranial and intracranial CAS (p = 0.042, OR = 1.428, 95% CI 1.014-2.012; p = 0.002, OR = 1.680, 95% CI 1.206-2.339), while RAS was independently associated with the degree of extracranial CAS (p = 0.001, OR = 2.880, 95% CI 1.556-5.329). Independent CPAS risk factors included an ischemic stroke history (p = 0.033), increased age (p < 0.01), as well as elevated fibrinogen (p = 0.021) and D-dimer levels (p = 0.019). In conclusion, the occurrence rates of RAS and PAD in ICVD patients with AS is relatively high, and with the severity of RAS or PAD increase, the severity of CAS also increase. Strengthening the evaluation of peripheral AS and controlling elevated fibrinogen might be crucial for preventing and delaying the progression of multiterritorial AS in ICVD patients with AS, thereby improving risk stratification and promoting more effective prevention and treatment strategies.

Renal ischemia alters the transcriptomic and epigenetic profile of inflammatory genes in swine scattered tubular-like cells

BACKGROUND

Scattered tubular-like cells (STCs) are differentiated renal tubular cells that during recovery from ischemic injury dedifferentiate to repair other injured renal cells. Renal artery stenosis (RAS), often associated with chronic inflammatory injury, compromises the integrity and function of STCs, but the underlying mechanisms remain unknown. We hypothesized that RAS alters the transcriptomic and epigenetic profile of inflammatory genes in swine STCs.

METHODS

STCs were harvested from pig kidneys after 10 weeks of RAS or sham (n=6 each). STC mRNA profiles of inflammatory genes were analyzed using high-throughput mRNA-sequencing (seq) and their DNA methylation (5mC) and hydroxymethylation (5hmC) profiles by DNA immunoprecipitation and next-generation sequencing (MeDIP-seq) (n=3 each), followed by an integrated (mRNA-seq/MeDIP-seq) analysis. STC protein expression of candidate differentially expressed (DE) genes and common proinflammatory proteins were subsequently assessed in vitro before and after epigenetic (Bobcat339) modulation.

RESULTS

mRNA-seq identified 57 inflammatory genes up-regulated in RAS-STCs versus Normal-STCs (>1.4 or <0.7-fold, P<0.05), of which 14% exhibited lower 5mC and 5% higher 5hmC levels in RAS-STCs versus Normal-STCs, respectively. Inflammatory gene and protein expression was higher in RAS-STCs compared with Normal-STCs but normalized after epigenetic modulation.

CONCLUSIONS

These observations highlight a novel modulatory mechanism of this renal endogenous repair system and support development of epigenetic or anti-inflammatory therapies to preserve the reparative capacity of STCs in individuals with RAS.

Renal Ischemia Induces Epigenetic Changes in Apoptotic, Proteolytic, and Mitochondrial Genes in Swine Scattered Tubular-like Cells

BACKGROUND

Scattered tubular-like cells (STCs) are dedifferentiated renal tubular cells endowed with progenitor-like characteristics to repair injured parenchymal cells. STCs may be damaged and rendered ineffective by renal artery stenosis (RAS), but the underlying processes remain unclear. We hypothesized that RAS alters the epigenetic landscape on DNA and the ensuing gene transcriptional profile of swine STCs.

METHODS

CD24+/CD133+ STCs were isolated from pig kidneys after 10 weeks of RAS or sham (n = 3 each) and their whole 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) profiles were examined by 5mC and 5hmC immunoprecipitation sequencing (MeDIP-/hMeDIP-seq, respectively). A subsequent integrated (MeDIP/hMeDIP-seq/mRNA-seq) analysis was performed by comparing all online available gene sets using Gene Set Enrichment Analysis. Apoptosis, proteolysis, and mitochondrial structure and function were subsequently evaluated in vitro.

RESULTS

Differential expression (DE) analysis revealed 239 genes with higher and 236 with lower 5mC levels and 275 genes with higher and 315 with lower 5hmC levels in RAS-STCs compared to Normal-STCs (fold change ≥1.4 or ≤0.7, p ≤ 0.05). Integrated MeDIP-/hMeDIP-seq/mRNA-seq analysis identified several overlapping (DE-5mC/mRNA and DE-5hmC/mRNA levels) genes primarily implicated in apoptosis, proteolysis, and mitochondrial functions. Furthermore, RAS-STCs exhibited decreased apoptosis, mitochondrial matrix density, and ATP production, and increased intracellular amino acid concentration and ubiquitin expression.

CONCLUSIONS

Renal ischemia induces epigenetic changes in apoptosis-, proteolysis-, and mitochondria-related genes, which correlate with alterations in the transcriptomic profile and corresponding function of swine STCs. These observations may contribute to developing novel targeted interventions to preserve the reparative potency of STCs in renal disease.

Emergent players in renovascular disease

Renovascular disease (RVD) remains a common etiology of secondary hypertension. Recent clinical trials revealed unsatisfactory therapeutic outcomes of renal revascularization, leading to extensive investigation to unravel key pathophysiological mechanisms underlying irreversible functional loss and structural damage in the chronically ischemic kidney. Research studies identified complex interactions among various players, including inflammation, fibrosis, mitochondrial injury, cellular senescence, and microvascular remodeling. This interplay resulted in a shift of our understanding of RVD from a mere hemodynamic disorder to a pro-inflammatory and pro-fibrotic pathology strongly influenced by systemic diseases like metabolic syndrome (MetS), hypertension, diabetes mellitus, and hyperlipidemia. Novel diagnostic approaches have been tested for early detection and follow-up of RVD progression, using new imaging techniques and biochemical markers of renal injury and dysfunction. Therapies targeting some of the pathological pathways governing the development of RVD have shown promising results in animal models, and a few have moved from bench to clinical research. This review summarizes evolving understanding in chronic ischemic kidney injury.

Metabolic Syndrome Alters the Cargo of Mitochondria-Related microRNAs in Swine Mesenchymal Stem Cell-Derived Extracellular Vesicles, Impairing Their Capacity to Repair the Stenotic Kidney

Background

Coexisting metabolic syndrome (MetS) and renal artery stenosis (RAS) are linked to poor renal outcomes. Mesenchymal stem/stromal cell- (MSC-) derived extracellular vesicles (EVs) from lean animals show superior ability to repair the experimental MetS+RAS kidney compared to EVs from MetS pig MSCs. We hypothesized that MetS leads to selective packaging in porcine EVs of microRNAs capable of targeting mitochondrial genes, interfering with their capacity to repair the MetS+RAS kidney.

Methods

Five groups of pigs (n = 7 each) were studied after 16 weeks of diet-induced MetS and RAS (MetS+RAS) and MetS+RAS 4 weeks after a single intrarenal delivery of EVs harvested from allogeneic adipose tissue-derived MSCs isolated from Lean or MetS pigs, and Lean or MetS sham controls. Single-kidney blood flow (RBF) and glomerular filtration rate (GFR) were assessed in vivo with multidetector CT, whereas EV microRNA cargo, renal tubular mitochondrial structure and bioenergetics, and renal injury pathways were assessed ex vivo.

Results

microRNA sequencing revealed 19 dysregulated microRNAs capable of targeting several mitochondrial genes in MetS-EVs versus Lean-EVs. Lean- and MetS-EVs were detected in the stenotic kidney 4 weeks after administration. However, only MetS-EVs failed to improve renal mitochondrial density, structure, and function or attenuate oxidative stress, tubular injury, and fibrosis. Furthermore, Lean-EVs but not MetS-EVs restored RBF and GFR in MetS+RAS.

Conclusion

MetS alters the cargo of mitochondria-related microRNAs in swine MSC-derived EVs, which might impair their capacity to repair the poststenotic kidney in MetS+RAS. These observations may contribute to develop approaches to improve the efficacy of MSC-EVs for patients with MetS.

Long-term outcomes and determinants of stenosis recurrence after renal artery angioplasty in hypertensive patients with renovascular disease

INTRODUCTION

Restenosis (RS) following percutaneous angioplasty (PTA) of renal artery stenosis (RAS) might have an unfavourable impact on renal function and blood pressure (BP) outcomes.

AIM

To evaluate the prevalence and predictors of RS in patients treated with PTA for RAS, and the relationship between BP and renal function (RF) changes with RS.

MATERIAL AND METHODS

We analysed freedom from RS in 210 patients (age 64.6 ±12.8 years; range: 20-85), who underwent 248 successful stent-assisted PTAs in RAS. The change in levels of serum creatinine (SCC), estimated glomerular filtration rate (eGFR), systolic/diastolic BPs (SBP/DBP) were analysed prior to PTA, at 6-, 12-month, and final follow-up visits, and whenever RS was diagnosed.

RESULTS

RS was identified in 30 (14.3%) patients, and there were 36 (14.5%) lesions. The Kaplan-Meier RS-free survival curves in fibromuscular dysplasia, atherosclerosis, and vasculitis at 1 and 7 years were: 100% and 100%; 95.6 and 83.9%; and 71.4 and 39.7%, respectively. Patients with RS, as compared to RS-free patients, presented with less pronounced changes in respect with: SBP (1.4 ±17.6 vs. -15.8 ±25.8 mm Hg; p = 0.01), DBP (2.64 ±10.1 vs. -6.5 ±14.1 mm Hg; p = 0.002), SCC (22.4 ±55.2 vs. -3.6 ±43.9 µmol/l; p = 0.002), and eGFR (-1.85 ±18 vs. -5.34 ±19.5 mm Hg; p = 0.045). In multivariate Cox regression analysis, independent predictors of RS occurred: lack of BP decrease (HR = 4.19, 95% CI: 1.67-10.3; p = 0.002), eGFR increase < 0.17 ml/min/1.73 m2 (HR = 2.93, 95% CI: 1.08-7.91; p = 0.033), stent diameter ≤ 5 mm (HR = 2.76, 95% CI: 1.09-6.97; p = 0.031), and vasculitis (HR = 5.61, 95% CI: 1.83-17.2; p = 0.003). RS was treated in 24 patients with RS recurrence in 20%.

CONCLUSIONS

The RS rate differs depending on RAS aetiology. Lack of SBP/DBP and eGFR improvement, vasculitis, and stent diameter are associated with RS risk. Repeated PTA is effective, but recurrent RS occurs in 20% of cases.

[Percutaneous angioplasty of renal artery stenosis: Short- and long-term results]

INTRODUCTION

Renal artery stenosis (RAS) may be symptomatic. The treatment of these lesions is primarily medical but may sometimes require surgical or endovascular revascularization. RAS angioplasty is well controlled but its results are discussed. The objective of this work was to report the short- and long-term results of the endovascular treatment of renal arteries in our center.

METHODS

We report a retrospective study between 2013 and 2018, including patients who received endovascular treatment for severe symptomatic RAS (≥75%).

RESULTS

Our population consisted of 17 patients. Mean age was 51.1 years [18-76], sex ratio 2.4. RAS was discovered during work-up for severe renovascular hypertension resistant to medical treatment for 16 patients and rapidly progressive renal failure for one patient. The etiology retained was: atherosclerosis (9 cases), fibromuscular dysplasia (6 cases) and Takayasu's disease (2 cases). The average stenosis rate was 85.9% [75-97%]. We performed simple angioplasty in 47% of the cases and stenting in 53%. The technical success rate was 100%. At 1 month, morbidity-mortality rates were zero. Mean follow-up was 12 months [6-36 months]. Patients with renovascular hypertension experienced a decrease in blood pressure, with discontinuation of antihypertensive therapy in 62.5% of cases and reduction of doses in 37.5% of cases. The permeability rate was 100% at 1 year, 94% at 2 years and 94% at 3 years. One patient had asymptomatic stent thrombosis at the 18th month. The restenosis rate was zero.

CONCLUSION

Angioplasty of symptomatic RAS may be indicated as first-line treatment. It is associated with satisfactory results in the short and long terms.

Atherosclerotic Renal Artery Stenosis: Should we Intervene Earlier?

Purpose of Review

Randomized trials have failed to show clinical benefit in patients with atherosclerotic renal artery stenosis who were treated with angioplasty with or without stenting. However, these studies were done in patients with a high-grade stenosis. This paper examines whether there are arguments to consider patients with low-grade stenosis for angioplasty.

Recent Findings

Patients with low-grade (< 50%) atherosclerotic renal artery stenosis have an excess risk for cardiovascular and renal complications. This could be related to inflammatory factors being generated by the stenotic kidney. Moreover, even a kidney with low-grade stenosis clears less or produces more of the natural nitric oxide inhibitor ADMA.

Summary

Patients with low-grade atherosclerotic renal artery stenosis have an increased risk for a variety of complications. In addition, the abnormality is progressive. There is a case for setting up a prospective trial to examine whether angioplasty confers benefit in patients with low-grade renal artery stenosis.

Peripheral vascular atherosclerosis in a novel PCSK9 gain-of-function mutant Ossabaw miniature pig model

Hypercholesterolemia is a major risk factor for atherosclerosis. Remaining challenges in the management of atherosclerosis necessitate development of animal models that mimic human pathophysiology. We characterized a novel mutant pig model with DNA transposition of D374Y gain-of-function (GOF) cDNA of chimp proprotein convertase subtilisin/kexin type-9 (PCSK9), and tested the hypothesis that it would develop peripheral vascular remodeling and target organ injury in the kidney. Wild-type or PCSK9-GOF Ossabaw miniature pigs fed a standard or atherogenic diet (AD) (n = 7 each) were studied in vivo after 3 and 6 months of diet. Single-kidney hemodynamics and function were studied using multidetector computed tomography and kidney oxygenation by blood oxygen level-dependent magnetic resonance imaging. The renal artery was evaluated by intravascular ultrasound, aortic stiffness by multidetector computed tomography, and kidney stiffness by magnetic resonance elastography. Subsequent ex vivo studies included the renal artery endothelial function and morphology of abdominal aorta, renal, and femoral arteries by histology. Compared with wild type, PCSK9-GOF pigs had elevated cholesterol, triglyceride, and blood pressure levels at 3 and 6 months. Kidney stiffness increased in GOF groups, but aortic stiffness only in GOF-AD. Hypoxia, intrarenal fat deposition, oxidative stress, and fibrosis were observed in both GOF groups, whereas kidney function remained unchanged. Peripheral arteries in GOF groups showed medial thickening and development of atheromatous plaques. Renal endothelial function was impaired only in GOF-AD. Therefore, the PCSK9-GOF mutation induces rapid development of atherosclerosis in peripheral vessels of Ossabaw pigs, which is exacerbated by a high-cholesterol diet. This model may be useful for preclinical studies of atherosclerosis.

Hypothalamic-pituitary-adrenal axis activity is associated with the prevalence of chronic kidney disease in diabetic patients

Progression of chronic kidney disease (CKD) in diabetic patients can occur through enhanced hypothalamic-pituitary-adrenal (HPA) axis activity. The purpose of our study was to determine whether HPA axis activity influences the prevalence of CKD in patients with type 2 diabetes mellitus. Seventy-seven diabetic patients (mean age, 60 years) were enrolled. CKD was defined by K/DOQI criteria, and serum cortisol level was measured after the 1 mg overnight dexamethasone suppression test (F-DST). F-DST values were significantly negatively correlated with estimated glomerular filtration rate (eGFR), and significantly positively correlated with cystatin C level and spot urine albumin to creatinine ratio in simple and multiple regression analyses. The subjects were divided into 3 groups (low, middle, and high) according to the F-DST, and the odds for CKD were 8.7-fold (95% confidence interval 2.56 to 29.6, P=0.01) and 12.5-fold (95% confidence interval 3.3 to 47.9, P<0.001) higher in subjects in the middle and high groups than those in the low group, respectively. In multivariate regression analysis, subjects in the middle group and high group (compared to those in the low group) had 13.0-fold (95% confidence interval, 2.9 to 58.8 and P=0.001) and 14.7-fold (95% confidence interval, 2.8 to 78.5 and P=0.002), respectively, higher risk for CKD. In conclusion, F-DST values have a relationship with decreased eGFR and increased cystatin C or albumin excretion involved in CKD, and enhanced HPA axis activity may be an independent risk factor for CKD in patients with type 2 diabetes mellitus.

Renoprotective Effects of Vitex megapotamica (Spreng.) Moldenke in C57BL/6 LDLr-Null Mice Undergoing High Fat Diet

Although Vitex megapotamica (Spreng.) Moldenke is used in Brazilian folk medicine as hypolipidemic drug no study has been conducted to evaluate the effects of this species in an experimental model of atherosclerosis. So, the aim of this study was to evaluate the possible renoprotective activity of methanolic extract obtained from Vitex megapotamica (MEVM) using C57BL/6 LDLr-null mice submitted to high fat diet (HFD). MEVM was orally administered at doses of 30, 100, and 300 mg/kg, for three weeks, starting from the 2nd week of HFD. Systolic blood pressure (SBP) and diuretic activity were measured weekly. At the end of experiments the serum lipids, atherogenic index serum (AIS), oxidative stress, and markers of renal function were determined. HFD induced a significant increase in the systolic blood pressure, dyslipidemia, increase in AIS, and lipid peroxidation accompanied by an important reduction in renal function. Treatment with MEVM was able to prevent increase in SBP, total cholesterol, triglycerides, AIS, urea, and creatinine levels in LDLr-null mice. These effects were accompanied by a significant reduction in oxidative stress and renal injury. The data reported here support the potential of Vitex megapotamica as candidate to be an herbal medicine used in cardiovascular or renal diseases.

A decline in glomerular filtration rate rather than renal arterial stenotic lesions, per se, predicts cardiovascular-renal events in type 2 diabetic patients

BACKGROUND

In diabetic patients with renal artery arteriosclerosis (RAAS), the factors associated with a greater risk for cardiovascular-renal events (CVREs) remain unclear: the decline in estimated glomerular filtration rate (eGFR) caused by RAAS or the advance of arteriosclerosis that causes RAAS. Hence, the features to determine which best predicts the onset of CVREs in such patients were compared.

METHODS AND RESULTS

The renal arteries of 162 type 2 diabetes patients were assessed by using magnetic resonance angiography (RAAS diagnosed as arteriosclerotic stenosis ≥50%) and they were studied longitudinally over 7 years. The influence of the presence/absence of RAAS, a decline in eGFR, clinical factors, surrogate arteriosclerotic markers and ischemic markers on patient's CVREs were assessed. A Cox regression analysis showed the detection of RAAS to be an independent risk factor for CVREs (bilateral RAAS was an extremely strong risk factor for the development of CVREs within 1,000 days), as was the decline in eGFR in a logistic regression analysis; the latter being a more powerful risk factor for CVREs. A multiple regression analysis revealed angiopoietin-2, a marker of ischemia, to be a risk factor for the decline in eGFR.

CONCLUSIONS

A decline in renal function but not the renal arterial stenotic lesion itself appears to be associated with an increased incidence of CVREs in type 2 diabetic patients with RAAS.

Renovascular hypertension leads to DNA damage and apoptosis in bone marrow cells

Angiotensin II (Ang II), which plays a pivotal role in the pathophysiology of the two-kidney, one-clip (2K1C) Goldblatt hypertension, has been associated with augmented generation of reactive oxygen species (ROS) in some cells and tissues. In the present study, we evaluated the influence of 2K1C hypertension on oxidative stress, DNA fragmentation, and apoptosis of bone marrow (BM) cells. Two weeks after the renal artery clipping or Sham operation, flow cytometry analysis showed a higher production of superoxide anions (approximately sixfold) and hydrogen peroxide (approximately twofold) in 2K1C hypertensive than in Sham normotensive mice. 2K1C mice also showed an augmented DNA fragmentation (54%) and apoptotic cells (21%). Our data show that the 2K1C renovascular hypertension is characterized by an increased production of ROS, DNA damage, and apoptosis of BM, which is a fundamental source of the cells involved in tissue repair.

Diagnosis and therapy of atheromatous renal artery stenosis

Atheromatous renal artery stenosis (ARAS), a lesion of systemic atherosclerotic disease, is the leading cause of stenotic lesions in the renal artery, followed by fibromuscular dysplasia, a primary abnormality of the renal artery. As a result of several clinical trails, which failed to show an additional benefit of renal revascularization to medical therapy in ARAS, the treatment of ARAS has shifted, and renal revascularization is less commonly performed for ARAS. However, it is recognized that renal revascularization benefits some patients with ARAS. Advances in imaging modalities would allow more frequent detection of ARAS in a society with a growing elderly population, a group with an increased prevalence of systemic atherosclerotic disease. Therefore, it is imperative to identify the patients with ARAS who could benefit from renal revascularization. This review presents a strategy for the treatment of ARAS based on the results of our analysis.

Clinical effect of endovascular treatment on blood pressure and kidney function for hypertensive patients with renal artery stenosis

The objective of this study was to evaluate the clinical effect of endovascular treatment on postoperative blood pressure (BP) control and kidney function of hypertensive patients with renal artery stenosis (RAS). Between January 2004 and December 2011, RAS was diagnosed in 120 renal arteries from 115 hypertensive patients. Preoperative and postoperative BPs and glomerular filtration rate (GFR) were monitored. Postoperative oral antiplatelet and antihypertensive agents were administered. Clinical follow-up was available for all patients for at least 6 months. Balloon angioplasty was performed successfully in 110 patients, and stents were deployed in 94 renal arteries from 89 patients. Hypertension was cured and lessened in 19 and 61 patients, respectively. Blood pressure was stable and worsened in 26 and 9 patients, respectively. The renal function was improved and stable in 23 patients and 57 patients, respectively. Deterioration of renal function was observed in 11 patients. Doppler ultrasound after discharge revealed 87 patent renal arteries and fixed stents in 82 patients 6 months after procedure. Balloon angioplasty and stent deployment are effective and feasible procedures for patients with RAS that help in controlling BP and improving renal function moderately.

Renovascular hypertension: screening and modern management

The diagnosis and management of patients with renovascular disease and hypertension continue to elude healthcare providers. The advent of novel imaging and interventional techniques, and increased understanding of the pathways leading to irreversible renal injury and renovascular hypertension, have ushered in commendable attempts to optimize and fine-tune strategies to preserve or restore renal function and control blood pressure. Large randomized clinical trials that compare different forms of therapy, and smaller trials that test novel experimental treatments, will hopefully help formulate innovative concepts and tools to manage the patient population with atherosclerotic renovascular disease.

Stage of chronic kidney disease is an outcome-predicting factor of angioplasty for atheromatous renal artery stenosis

Angioplasty with insertion of an endoprosthesis is an effective treatment for atheromatous renal artery stenosis (ARAS). However, this procedure may cause deterioration in renal function, and it is imperative to define the cases that could benefit from angioplasty. From 456 suspected renovascular hypertension cases, 33 were given a diagnosis of unilateral ARAS on renal arteriography. These unilateral ARAS cases were treated by angioplasty, and their baseline variables were evaluated with respect to the improvement achieved in post-angioplastic renal function of the treated side as measured by renal scintigram. The estimated glomerular filtration rate (eGFR) was the only variable that was significantly different between cases that showed improvement in renal function and those that did not. Cases that showed improvement in renal function had lower pre-angioplasty eGFR compared with cases that did not show improvement (59±24 ml min⁻¹ 1.73 m⁻² vs. 76±12 ml min⁻¹ 1.73 m⁻², P=0.04), and cases showing improvement were generally at later stages of chronic kidney disease (CKD). Most patients without improvement, who were generally at earlier stages of CKD, had a systemic blood pressure reduction after angioplasty. The present findings indicate that the baseline CKD stage could be used to predict the outcome of angioplasty for ARAS.

Mechanisms of tissue injury in renal artery stenosis: ischemia and beyond

Renal injury distal to an atherosclerotic renovascular obstruction reflects multiple intrinsic factors producing parenchymal tissue injury. Atherosclerotic disease pathways superimposed on renal arterial obstruction may aggravate damage to the kidney and other target organs, and some of the factors activated by renal artery stenosis may in turn accelerate the progression of atherosclerosis. This cross-talk is mediated through amplified activation of renin-angiotensin system, oxidative stress, inflammation, and fibrosis-pathways notoriously involved in renal disease progression. Oxidation of lipids also accelerates the development of fibrosis in the stenotic kidney by amplifying profibrotic mechanisms and disrupting tissue remodeling. The extent to which actual ischemia modulates injury in the stenotic kidney has been controversial, partly because the decrease in renal oxygen consumption usually parallels a decrease in renal blood flow, and because renal vein oxygen pressure in the affected kidney is not decreased. However, recent data using novel methodologies demonstrate that intra-renal oxygenation is heterogeneously affected in different regions of the kidney. Activation of such local injury within the kidney may lead to renal dysfunction and structural injury, and ultimately unfavorable and irreversible renal outcomes. Identification of specific pathways producing progressive renal injury may enable development of targeted interventions to block these pathways and preserve the stenotic kidney.

Angiotensin inhibition in renovascular disease: a population-based cohort study

BACKGROUND

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers effectively reduce blood pressure in patients with renovascular disease (RVD); yet, randomized cardiovascular prevention trials of these drugs typically exclude individuals with this condition.

PATIENTS AND METHODS

We studied the association of renin-angiotensin system inhibition with prognosis in a population-based cohort comprising 3,570 patients with RVD in Ontario, Canada; slightly more than half (n = 1,857, 53%) were prescribed angiotensin inhibitors. The primary outcome was the composite of death, myocardial infarction, or stroke. Secondary outcomes included individual cardiovascular and renal events.

RESULTS

Patients receiving angiotensin inhibitors had a significantly lower risk for the primary outcome during follow-up (10.0 vs 13.0 events per 100 patient-years at risk, multivariable adjusted hazard ratio [HR] 0.70, 95% CI 0.59-0.82). In addition, hospitalization for congestive heart failure (HR 0.69, 95% CI 0.53-0.90), chronic dialysis initiation (HR 0.62, 95% CI 0.42-0.92), and mortality (HR 0.56, 95% CI 0.47-0.68) was lower in treated patients. Conversely, patients receiving angiotensin inhibitors were significantly more likely to be hospitalized for acute renal failure during follow-up (HR 1.87, 95% CI 1.05-3.33; 1.2 vs 0.6 events per 100 patient-years at risk).

CONCLUSIONS

These data emphasize the high vascular risk of RVD and suggest that angiotensin inhibitors may improve prognosis in this setting at the expense of acute renal toxicity. If the latter are selected in the management of RVD, renal function parameters should be assiduously followed.

Angiographic index for angioplasty-treatable atheromatous renal artery stenosis

The relative reduction of the lumen diameter by an atheromatous lesion (% diameter reduction) is generally used as an angiographic index for atheromatous renal artery stenosis (ARAS), but its association with the clinical outcome of angioplasty has not been sufficiently evaluated. This study aimed to identify an angiographic index(ices) that can be used to identify angioplasty-treatable ARAS. We evaluated the clinical outcome of angioplasty in 27 patients who had unilateral ARAS without renal insufficiency by assessing the reduction in systemic arterial blood pressure (BP) after angioplasty and examined its association with various angiographic indices. In the receiver operating characteristic analysis for BP reduction, the area under the curve was larger for the absolute value of the lumen diameter at the narrowest part of its constriction (the narrowest diameter), an angiographic index introduced in this study, than for % diameter reduction (0.770 vs. 0.731). At a 3-mm maximum threshold, the narrowest diameter identified cases with BP reduction; the sensitivity/specificity was 0.89/0.75 (p < 0.001). Furthermore, the narrowest diameter correlated better than % diameter reduction with hemodynamic indices of ARAS. In conclusion, the narrowest diameter is an angiographic index that can effectively identify angioplasty-treatable ARAS in patients without renal insufficiency.

[Prevalence of renal artery stenosis in patients with critical limb ischemia]

BACKGROUND AND OBJECTIVE

Our purpose was to evaluate the prevalence of renal artery stenosis in patients with critical limb ischemia and to study any clinical or laboratory indicator that could predict this association.

PATIENTS AND METHOD

One hundred consecutive patients with critical limb ischemia evaluated by angiogram were included in the study from January to July 2003. Cardiovascular risk factors and renal function were analyzed.

RESULTS

One hundred angiographic studies have been analyzed. Thirty nine (39%) of our patients had some type of pathology of the renal artery but the rest, 61 (61%), had normal and healthy renal arteries. In 5 patients, a bilateral renal pathology was found. Severe disease (> 60% stenosis, bilateral or renal occlusion) was present in 15 cases including 6 occlusions. Once we compared the patients with healthy renal arteries with the patients with different degrees of stenosis, we did not appreciate significant differences in hypertension, diabetes, coronary disease or smoking habit, nor with laboratory data such as creatinine, urea, c-reactive protein, total cholesterol or atherogenic index. No differences were found either comparing patients with normal renal artery with patients with bilateral pathology or with unilateral occlusion.

CONCLUSIONS

There is a high prevalence of renal artery pathology in patients with critical limb ischemia although we have not found any clinical or laboratory factors useful to identify them.

Renal artery stent revascularization with embolic protection in patients with ischemic nephropathy

A prospective analysis of renal artery stent revascularization with distal embolic protection in a high-risk patient population with ischemic nephropathy is presented. A total of 63 patients (median age 70.2 years, range 54-86 years) had significant atherosclerotic stenosis of 83 renal arteries documented on pre-procedural imaging. All patients had baseline chronic renal insufficiency with a documented deterioration in renal function in the 6 months before revascularization. The endovascular technique used in all patients involved primary passage of an embolic filter into the distal main renal artery followed by primary stent deployment with a balloon expandable stainless steel stent. The filter baskets were recaptured and contents submitted for pathological analysis. At 6 months post-intervention, 97% of patients demonstrated stabilization or improvement in renal function. Only 3% of patients had an inexorable decline in renal function, unchanged by the intervention. After a mean follow up of 16.0 months (6-27), 94% of patients demonstrated stabilization or improvement in renal function. One patient suffered an acute post-procedural deterioration in renal function. In total, 60% of the filter baskets contained embolic material. This study confirms the technical feasibility of renal artery stent deployment with adjuvant embolic protection. The excellent results for renal preservation at 6 months post-intervention also suggest that a distal embolic protection device may improve the impact of percutaneous renal revascularization on progressive deterioration in renal function. The postulated mechanism is through the prevention of atheromatous embolization and the embolic yield from the distal filters supports this hypothesis. Patients most likely to receive the greatest benefit are those with mild baseline chronic renal insufficiency and a recent decline in renal function.

Atherosclerotic renovascular disease

Atherosclerotic renovascular disease is a combination of renal artery stenosis and renal ischemia. Blood pressure does not rise until the stenosis is 60% or greater. Disease of both large and small blood vessels is often accompanied by the loss of glomerular filtration rate. Activation of the renin-angiotensin-aldosterone system leads to vasoconstriction and salt retention. Risk factors for atherosclerotic renovascular disease include long-standing hypertension, diabetes, smoking and dyslipidemia. The prevalence of the condition in patients with hypertension resistant to two medications is 20%. As yet, there is no single ideal screening test or evidence-based recommended screening algorithm. Magnetic resonance angiography and computed tomography angiography are noninvasive and have high sensitivity and specificity, but also have high costs associated with them. The captopril renal scan has low sensitivity and specificity in people with renal disease (the population most likely to require the test). Doppler ultrasonography has high sensitivity and specificity in experienced hands, and the renal resistance index, which can easily be added to this test, can identify those with microvascular disease who may not benefit from revascularization. The best determinant of patient outcome is not the degree of renal artery stenosis but the degree of renal parenchymal disease. To date, renal revascularization has not been associated with improved renal survival compared with medical treatment alone. Today, the approach to atherosclerotic renovascular disease is determined by the patient's blood pressure and renal function; possibly, in the future, it will be determined by the result of the renal resistance index as part of a screening algorithm. If the blood pressure is uncontrollable or the renal function is deteriorating, the patient should be considered for renal revascularization initially, with a percutaneous endovascular stent. The management of hypertension involves the use of combinations of antihypertensive agents at doses sufficient to control blood pressure. Medical management also includes aggressive lipid-lowering therapy.

Atherosclerotic Disease: Whole-Body Cardiovascular Imaging with MR System with 32 Receiver Channels and Total-Body Surface Coil Technology—Initial Clinical Results

In this prospective study, the feasibility of a comprehensive cardiovascular imaging protocol with a dedicated whole-body 1.5-T magnetic resonance (MR) imager with 32 receiver channels in 34 patients with peripheral arterial occlusive disease was evaluated. Informed consent and institutional review board approval were obtained. Three-dimensional MR angiographic data sets were acquired with adapted injection protocol. Cardiac functional imaging and delayed-enhancement imaging were performed, as were fluid-attenuated inversion-recovery imaging of the brain and time-of-flight MR angiography of the intracranial blood vessels. Sensitivity and specificity for depiction of significant vascular stenosis (> 70%) were 96%, with conventional digital subtraction angiography as the standard. Substantial microangiopathic tissue alterations (n = 4) and/or cerebral infarction (n = 4) were diagnosed in seven patients. In seven patients, subendocardial or transmural delayed enhancement was detected in corresponding regions, indicating prior myocardial infarction. Previously unknown findings diagnosed with MR imaging required midterm follow-up or therapy in 24 patients, whereas change of therapy or immediate treatment was necessary in three. For patients suspected of having systemic atherosclerotic disease, comprehensive risk assessment is feasible within 30 minutes.

Predictors of undiagnosed renal artery stenosis among Japanese patients with risk factors of atherosclerosis

Atherosclerotic renal artery stenosis (ARAS) is a significant cause of end stage renal dysfunction (ESRD) among the elderly. Although early detection of ARAS and induction of adequate treatment could reduce the incidence of ESRD, there have been few reports about parameters predictive of ARAS among Japanese. In this study, we investigated the clinical indicators that predict ARAS among Japanese with risk factors of atherosclerosis (> 40 years of age plus hypertension, dyslipidemia or diabetes mellitus). After eliminating the patients who had already been diagnosed with renal artery stenosis, 202 patients were enrolled. The renal arteries of all 202 patients were evaluated by magnetic resonance arteriography (MRA), and the stenoses with > 50% reduction in diameter at the ostium of the renal artery were defined as ARAS. MRA detected ARAS in 42 patients (31 hemilateral and 11 bilateral). Between the patients with and without ARAS there was no significant difference in gender distribution, detection of abdominal vascular bruits or smoking habit. The prevalences of diabetic, hypertensive and cerebrovascular comorbidity were also not significantly different. The mean blood pressure, body mass index and total serum cholesterol values were similar between the two groups. However, age, pulse pressure, serum uric acid, serum creatinine, amount of urinary protein, and coronary artery comorbidity were significantly higher, while estimated creatinine clearance was significantly lower in the patients with ARAS than in those without ARAS. A high prevalence of hypertensive retinopathy was also noted among patients with ARAS. Multivariate analysis revealed that older age and renal impairment were independent predictors of ARAS in Japanese patients with atherosclerotic risk factors.

Evaluation of the Safety and Effectiveness of Renal Artery Stenting After Unsuccessful Balloon Angioplasty

OBJECTIVES

This study sought to define the safety and durability of renal stenting after suboptimal/failed renal artery angioplasty in patients with suspected renovascular hypertension.

BACKGROUND

Few prospective multicenter studies have detailed the safety, efficacy, and long-term clinical benefits of renal artery stent revascularization in hypertensive patients with aorto-ostial atherosclerotic renal artery lesions.

METHODS

This non-randomized study enrolled 208 patients with de novo or restenotic > or = 70% aorto-ostial renal artery stenoses, who underwent implantation of a balloon-expandable stent after unsuccessful percutaneous transluminal renal angioplasty (PTRA), which was defined as a > or = 50% residual stenosis, persistent translesional pressure gradient, or a flow-limiting dissection. The primary end point was the nine-month quantitative angiographic or duplex ultrasonography restenosis rate adjudicated by core laboratory analysis. Secondary end points included renal function, blood pressure, and cumulative incidence of major adverse events and target lesion revascularization at 24 months.

RESULTS

The stent procedure was immediately successful in 182 of 227 (80.2%) lesions treated. The nine-month restenosis rate was 17.4%. Systolic/diastolic blood pressure decreased from 168 +/- 25/82 +/- 13 mm Hg (mean +/- standard deviation) at baseline to 149 +/- 24/77 +/- 12 mm Hg at 9 months (p < 0.001 vs. baseline), and 149 +/- 25/77 +/- 12 mm Hg at 24 months (p < 0.001 vs. baseline). Mean serum creatinine concentration was unchanged from baseline values at 9 and 24 months. The 24-month cumulative rate of major adverse events was 19.7%.

CONCLUSIONS

In hypertensive patients with aorto-ostial atherosclerotic renal artery stenosis in whom PTRA is unsuccessful, Palmaz (Cordis Corp., Warren, New Jersey) balloon-expandable stents provide a safe and durable revascularization strategy, with a beneficial impact on hypertension.

Two cases of renovascular hypertension and ischemic renal dysfunction: reliable choice of examinations and treatments

We experienced two aged patients with atherosclerotic renovascular stenosis associated with hypertension and ischemic nephropathy. Both patients exhibited sudden rise in blood pressure (BP) and progressive aggravation of renal dysfunction. In these patients, the use of contrast medium to screen for renal artery stenosis (RAS) ran the risk of further deterioration of renal function. We therefore used magnetic resonance angiography (MRA), which is less conducive to renal damage, to screen for RAS. One-sided RAS was treated by percutaneous transluminal angioplasty of the renal artery (PTRA) and stenting. As a result, BP decreased in both patients. Serum creatinine (Cr) decreased slightly in one patient, whereas, in the other, serum Cr increased transiently and then decreased and stabilized to pre-treatment levels. Thus, although it is unclear whether the combination of PTRA and stenting is among the best treatments for patients with RAS and moderate-to-severe renal dysfunction, PTRA and stenting are clearly of benefit in selected patients. In addition, recent progress in characterizing the pathophysiology of ischemic nephropathy associated with renovascular hypertension has created interest in the therapeutic potential of angiotensin II receptor antagonists, sympatholytic agents, and antioxidants. Therefore, we discuss the therapeutic utility of PTRA and stenting and the above-mentioned medications in patients with RAS and renal dysfunction.

Kidney in early atherosclerosis

Atherosclerosis represents one of the major causes of premature death in the United States today, and it is frequently associated with, exacerbates, and is aggravated by chronic kidney disease (CKD). Atherosclerosis integrates the response to a number of insults, and consequently, the accelerated atherosclerosis found in CKD patients is associated with activation of a variety of humoral and tissue mechanisms. Hypertension, diabetes, dyslipidemia, obesity, metabolic syndrome, and additional nontraditional risk factors can damage the kidney directly and by promoting intrarenal atherogenesis, even in the absence of obstructive lesions in the renal artery. Evidence indicates that increased oxidative stress and inflammation may mediate a large part of the effects of risk factors on the kidney. In turn, progressive deterioration of renal function in CKD may lead to dyslipidemia or accumulation of uremic toxins, which can induce production of free radicals and activate proinflammatory and fibrogenic factors, leading to vascular endothelial cell dysfunction and injury, and favoring development of atherosclerosis. Therefore, the kidney can be a villain or a victim during atherogenesis. The purpose of this review is to provide new insights into the mechanisms by which atherogenic factors may instigate early renal injury.

A single chinese center investigation of renal artery stenosis in 141 consecutive cases with coronary angiography

BACKGROUND

There is an increasing prevalence of ischemic nephropathy in the aging population of the world. However, the exact incidence of ischemic nephropathy in the Chinese population is still uncertain. The present study investigated the incidence of renal artery stenosis (RAS) in patients with suspected coronary artery disease (CAD) using renal angiography.

METHODS

Renal angiography was performed immediately after coronary artery angiography in 141 patients with suspected CAD, including 59 males and 82 females whose mean ages were 59 +/- 10 years. Comorbidities included hypertension (n = 69), diabetes mellitus (n = 21), hyperlipidemia (n = 19), hypokalemia (n = 7) and preoperative renal insufficiency (Cr >132 micromol/l; n = 14). The patients were divided into CAD (luminal narrowing of > or =50%) and non-CAD (luminal narrowing of <50%) subgroups, and RAS (luminal narrowing of > or =50%) and non-RAS subgroups. In the RAS group, there were 11 patients (5 males, 6 females) in whom percutaneous transluminal renal angioplasty was performed in conjunction with stent implantation due to refractory hypertension.

RESULTS

The incidence of RAS was 18.4% (26/141) in all cases and 30.8% (16/52) in patients with CAD identified by coronary artery angiography. Ten cases with RAS were found among the 89 cases with normal coronary arteries (11.2%). The incidence of RAS in patients with CAD was higher than that in patients without CAD (30.8 vs. 11.2%, p< 0.05). In 52 cases with CAD, the incidence of RAS with three vessel lesions was significantly higher than that with one or two vessel lesions. Hypertension, CAD, renal insufficiency, hyperlipidemia and hypokalemia were associated with a higher risk of RAS.

CONCLUSIONS

This study suggests that RAS is very common in the elderly Chinese population, specifically for those with three vessel lesions in CAD. For early detection of potential ischemic nephropathy, renal angiography is necessary in patients who receive coronary artery angiography.

Angiotensin-Converting Enzyme Inhibitor Usage in Patients with Incidental Atherosclerotic Renal Artery Stenosis

The efficacy of angiotensin converting enzyme (ACE) inhibitors in treatment of renovascular disease has been controversial. It has been reported that patients with incidental atherosclerotic renal artery stenosis (ARAS) are sometimes treated with ACE inhibitors before being considered for renal revascularization. This study was designed to describe the frequency and the characteristics of patients with incidental ARAS, and to examine the frequency of ACE inhibitor usage in such patients. We studied a cohort of consecutive patients undergoing abdominal aortography at the time of cardiac catheterization. Patients were stratified and compared based on the presence and severity of ARAS. ARAS (> or =50%) was present in 146 (17.0%) of 859 evaluable patients. Factors independently related to the presence of ARAS were age (odds ratio (OR)=1.07, p < 0.001), severity of coronary artery disease (OR=2.13, p < 0.001) and peripheral vascular disease (OR=1.79, p = 0.021). Among all patients with ARAS, the percentage of ACE inhibitor usage was 74.7% (109/146). Among patients with severe ARAS, moderate ARAS, mild ARAS, insignificant ARAS and normal renal arteries, the percentage of ACE inhibitor usage was 85.7% (95% confidence interval (CI): 69-100%), 82.9% (95% CI: 71-95%), 68.5% (95% CI: 59-78%), 68.6% (95% CI: 55-82%) and 53.9% (95% CI: 50-58%), respectively (contingency coefficient=0.17, p < 0.001). In patients with severe ARAS, ACE inhibitor use, calcium channel blocker use and diuretic use were shown to correlate significantly with serum creatinine levels after controlling for potential confounding factors. In this study, ACE inhibitors were used commonly in patients with incidental ARAS; the frequency of ACE inhibitor use correlated with the severity of ARAS.