The role of percutaneous revascularization for renal artery stenosis

Evaluating Short-Term and Long-Term Risks Associated with Renal Artery Stenosis Position and Severity: A Hemodynamic Study

Background: Moderate renal artery stenosis (50-70%) may lead to uncontrolled hypertension and eventually cause irreversible damage to renal function. However, the clinical criteria for interventional treatment are still ambiguous in this condition. This study investigated the impact of the position and degree of renal artery stenosis on hemodynamics near the renal artery to assess the short-term and long-term risks associated with this disease. Methods: Calculation models with different degrees of stenosis (50%, 60%, and 70%) located at different positions in the right renal artery were established based on the computed tomography angiography (CTA) of a personalized case. And computational fluid dynamics (CFD) was used to analyze hemodynamic surroundings near the renal artery. Results: As the degree of stenosis increases and the stenosis position is far away from the aorta, there is a decrease in renal perfusion. An analysis of the wall shear stress (WSS)-related parameters indicated areas near the renal artery (downstream of the stenosis and the entrance of the right renal artery) with potential long-term risks of thrombosis and inflammation. Conclusion: The position and degree of stenosis play a significant role in judging short-term risks associated with renal perfusion. Moreover, clinicians should consider not only short-term risks but also independent long-term risk factors, such as certain regions of 50% stenosis with adequate renal perfusion may necessitate prompt intervention.

The Maintained Glycemic Target Goal and Renal Function Are Associated with Cardiovascular and Renal Outcomes in Diabetic Patients Following Stent-Supported Angioplasty for Renovascular Atherosclerotic Disease

Patients with type 2 diabetes mellitus (T2DM) constitute a large proportion of patients with atherosclerotic renal artery stenosis (ARAS). However, the mechanism of impaired renal function and hypertension in this subset of patients is multifactorial. We aimed to investigate whether, in diabetic patients, renal function (RF), systolic (SBP) and diastolic blood pressure (DBP) values following stent-supported angioplasty (PTA) for ARAS have an impact on cardiovascular and renal outcomes. Methods: The study group included 93 patients with T2DM and resistant hypertension who underwent PTA for ARAS. The pre- and post-procedure (6 to 12, and 24 months) values of SBP, DBP, eGFR and glycaemia were obtained. The prospective follow-up of median 44 months was performed for combined outcome: major cardiac and cerebral events (MACCE) and progression to renal replacement therapy (RRT). Results: MACCE-RRT occurred in 46 (49.5%) patients, with higher incidence in patients with higher values of SBP (147.8 ± 25.8 vs. 136.7 ± 15.8 mmHg, p = 0.006), DBP (80.8 ± 13.3 vs. 74.4 ± 12.3 mmHg, p = 0.009), chronic kidney disease in stages 3B to 5 (p = 0.029) and those who have not obtained target glycemic goals compared to well-maintained T2DM (p = 0.007) at 24-months. On multivariate Cox analysis, well-maintained T2DM targets [Hazard Ratio (HR):0.27; 95% Confidence Interval (CI):0.13−0.57; p < 0.001], eGFR below 45 mL/min/m2 (HR: 2.20; 95%CI: 1.20−4.04; p = 0.011), previous stroke (HR:2.52; 95%CI:1.19−5.34; p = 0.015) retained their associations with MACCE-RRT, while BP values were not associated with the outcome. Conclusions: The post-procedural RF, maintained glycemic target goal and previous stroke are vital for the outcome in patients undergoing PTA for renovascular disease in diabetic patients.

Distribution of atherosclerotic lesions in various arteries of WHHLMI rabbits, an animal model of familial hypercholesterolemia

In WHHLMI rabbits, arterial lesions develop spontaneously in various arteries even with standard chow. Here, we examined the development of arterial lesions in various arteries to demonstrate standard characteristics of arterial lesions in WHHLMI rabbits. For WHHLMI rabbits at 6, 12, 20, and 30 months of age, lesion areas and areas of arterial lumen surfaces were measured using image analysis software. Histopathological sections of arterial lesions were stained with elastic van Gieson staining. Arterial lesions developed around bifurcations and expanded with aging. In the aorta, atheromatous lesions were severe in the thoracic aorta but were mild in the distal part of the abdominal aorta. Carotid artery lesions progressed in the proximal region and at bifurcations, and the histopathological features were similar to those of coronary lesions. Pulmonary artery lesions contained many foam cells. Fibrous lesions were observed in the proximal and distal areas of the renal arteries, at the bifurcation of the iliac-femoral artery and mesenteric artery, and around the anastomosis of vertebral arteries. Lesions in the celiac artery contained foam cells and/or lipid droplets within fibrous lesions. In a pair of right and left arteries, the arterial lesions tended to progress more in the right artery. Gender did not affect analysis of arterial lesions. In conclusion, the arterial lesions expanded from bifurcations, and the morphological features of the arterial lesions varied depending on the type of artery. These results serve as reference data for arterial lesions in studies using WHHLMI rabbits.

Flow visualisation study of spiral flow in the aorta-renal bifurcation

The aim of this study was to analyse the flow dynamics in an idealised model of the aorta-renal bifurcation using flow visualisation, with a particular focus on the effect of aorta-to-renal flow ratio and flow spirality. The recirculation length was longest when there was low flow in the renal artery and smaller in the presence of spiral flow. The results also indicate that patients without spiral flow or who have low flow in the renal artery due to the presence of stenosis may be susceptible to heightened development of atherosclerotic lesions.

Recirculation zone length in renal artery is affected by flow spirality and renal-to-aorta flow ratio

Haemodynamic perturbations such as flow recirculation zones play a key role in progression and development of renal artery stenosis, which typically originate at the aorta-renal bifurcation. The spiral nature of aortic blood flow, division of aortic blood flow in renal artery as well as the exercise conditions have been shown to alter the haemodynamics in both positive and negative ways. This study focuses on the combinative effects of spiral component of blood flow, renal-to-aorta flow ratio and the exercise conditions on the size and distribution of recirculation zones in renal branches using computational fluid dynamics technique. Our findings show that the recirculation length was longest when the renal-to-aorta flow ratio was smallest. Spiral flow and exercise conditions were found to be effective in reducing the recirculation length in particular in small renal-to-aorta flow ratios. These results support the hypothesis that in renal arteries with small flow ratios where a stenosis is already developed an artificially induced spiral flow within the aorta may decelerate the progression of stenosis and thereby help preserve kidney function.

Multimarker assessment for the prediction of renal function improvement after percutaneous revascularization for renal artery stenosis

BACKGROUND

Identifying patients likely to have improved renal function after percutaneous transluminal renal angioplasty and stenting (PTRA) for renal artery stenosis (RAS) is challenging. The purpose of this study was to use a comprehensive multimarker assessment to identify those patients who would benefit most from correction of RAS.

METHODS

In 127 patients with RAS and decreased renal function and/or hypertension referred for PTRA, quantification of hemodynamic cardiac stress using B-type natriuretic peptide (BNP), renal function using estimated glomerular filtration rate (eGFR), parenchymal renal damage using resistance index (RI), and systemic inflammation using C-reactive protein (CRP) were performed before intervention.

RESULTS

Predefined renal function improvement (increase in eGFR ≥10%) at 6 months occurred in 37% of patients. Prognostic accuracy as quantified by the area under the receiver-operating characteristics curve for the ability of BNP, eGFR, RI and CRP to predict renal function improvement were 0.59 (95% CI, 0.48-0.70), 0.71 (95% CI, 0.61-0.81), 0.52 (95% CI, 0.41-0.65), and 0.56 (95% CI, 0.44-0.68), respectively. None of the possible combinations increased the accuracy provided by eGFR (lower eGFR indicated a higher likelihood for eGFR improvement after PTRA, P=ns for all). In the subgroup of 56 patients with pre-interventional eGFR <60 mL/min/1.73 m(2), similar findings were obtained.

CONCLUSIONS

Quantification of renal function, but not any other pathophysiologic signal, provides at least moderate accuracy in the identification of patients with RAS in whom PTRA will improve renal function.

Renal artery stenosis and mean platelet volume

Objective:

Increased mean platelet volume (MPV) has been reported in various atherosclerotic diseases. The aim of our study was to investigate the relationship between the atherosclerotic renal artery stenosis (ARAS) and various hematological parameters including MPV.

Methods:

This study was performed with a retrospective review of the angiographic images of patients who underwent renal angiography at Bülent Ecevit University catheter laboratory between January 2004 and December 2009. The patients were trichotomized into three groups based on the presence and severity of renal artery stenosis (RAS). Group 1 included patients with a critical RAS (33 patients; 18 female (F), 15 male (M); mean age 61.6±11.5 years), group 2 consisted of patients with non-critical RAS (26 patients; 15 F, 11 M; mean age 58.1±11.3 years), and group 3 was composed of patients without RAS (69 patients; 38 F, 31 M; mean age 53.5±11.9 years). Demographic data, complete blood count, and biochemical parameters were compared between the groups.

Results:

Comparison of the hematological parameters revealed that MPV and platelet distribution width were significantly higher in group 1 than in group 2 and 3 (8.96±0.99 fL versus 8.35±0.76 fL, 8.31±0.79 fL, respectively; p=0.001; 16.53±0.58% versus 16.19±0.56%, 16.29±0.53%, respectively; p=0.04).

Conclusion:

MPV levels are higher in patients with ARAS. Considering both the effect of platelets on atherosclerosis and their close association with other risk factors, MPV level may be an important factor in pathogenesis of ARAS.

Spiral blood flow in aorta-renal bifurcation models

The presence of a spiral arterial blood flow pattern in humans has been widely accepted. It is believed that this spiral component of the blood flow alters arterial haemodynamics in both positive and negative ways. The purpose of this study was to determine the effect of spiral flow on haemodynamic changes in aorta-renal bifurcations. In this regard, a computational fluid dynamics analysis of pulsatile blood flow was performed in two idealised models of aorta-renal bifurcations with and without flow diverter. The results show that the spirality effect causes a substantial variation in blood velocity distribution, while causing only slight changes in fluid shear stress patterns. The dominant observed effect of spiral flow is on turbulent kinetic energy and flow recirculation zones. As spiral flow intensity increases, the rate of turbulent kinetic energy production decreases, reducing the region of potential damage to red blood cells and endothelial cells. Furthermore, the recirculation zones which form on the cranial sides of the aorta and renal artery shrink in size in the presence of spirality effect; this may lower the rate of atherosclerosis development and progression in the aorta-renal bifurcation. These results indicate that the spiral nature of blood flow has atheroprotective effects in renal arteries and should be taken into consideration in analyses of the aorta and renal arteries.

Effect of Huanshuai Recipe Oral Liquid ([characters: see text]) on renal dysfunction progression in patients with atherosclerotic renal artery stenosis

OBJECTIVE

To investigate the effect of Huanshuai Recipe Oral Liquid ([characters: see text], HSR) on retarding the progression of renal dysfunction in patients with atherosclerotic renal artery stenosis (ARAS).

METHODS

A total of 52 ARAS patients with the Chinese medicine (CM) syndrome of qi deficiency and blood stasis, phlegm and dampness retention were recruited and randomly assigned into the treatment group (36 cases) and the control group (16 cases). Both groups received a basic treatment (high-quality low-protein diet, blood pressure control, lipid-lowering, correcting the acidosis, etc.). In addition, the treatment group received 20 mL HSR and the control group received placebo, 3 times a day for 6 months. Renal function (serum creatinine, blood urea nitrogen and uric acid) and blood lipids (cholesterol, triglycerides and low density lipoprotein) were examined monthly. The estimated glomerular filtration rate (eGFR) and CM syndrome score were compared between groups.

RESULTS

After treatment, compared with the control group, the serum creatinine level, uric acid level and CM syndrome score of the treatment group were significantly decreased (P<0.05 or P<0.01), and the eGFR in the treatment group were significantly increased (P<0.05).

CONCLUSION

HSR can effectively improve the renal function and clinical symptoms of ARAS patients.

Surgical, interventional, and device innovations in the management of hypertension

The prevalence of hypertension around the world has increased significantly with projections for an increasing major global burden of hypertension. Medication-resistant hypertension can be perplexing and frustrating. The existence of these difficult patients results in the need for additional approaches to treatment including surgery, percutaneous interventions, and device management. The sophistication of these techniques has progressed markedly and initial procedures such as classical sympathectomy and renal artery bypass are almost never performed. Newer techniques of angioplasty with stenting, renal artery denervation, and baroreflex activation therapy via electrical stimulation of the carotid baroreceptors are now in use with increasing evidence for significant benefit.

Transcatheter therapies for resistant hypertension: Clinical review

Resistant hypertension (RHTN) is a commonly encountered clinical problem and its management remains a challenging task for healthcare providers. The prevalence of true RHTN has been difficult to assess due to pseudoresistance and secondary hypertension. Atherosclerotic renal artery stenosis (RAS) has been associated as a secondary cause of RHTN. Initial studies had shown that angioplasty and stenting for RAS were a promising therapeutic option when added to optimal medical management. However, recent randomized controlled trials in larger populations have failed to show any such benefit. Sympathetic autonomic nervous system dysfunction is commonly noted in individuals with resistant hypertension. Surgical sympathectomy was the treatment of choice for malignant hypertension and it significantly improved mortality. However, post-surgical complications and the advent of antihypertensive drugs made this approach less desirable and it was eventually abandoned. Increasing prevalence of RHTN in recent decades has led to the emergence of minimally invasive interventions such as transcatheter renal denervation for better control of blood pressure. It is a minimally invasive procedure which uses radiofrequency energy for selective ablation of renal sympathetic nerves located in the adventitia of the renal artery. It is a quick procedure and has a short recovery time. Early studies in small population showed significant reduction in blood pressure. The most recent Symplicity HTN-3 study, which is the largest randomized control trial and the only one to use a sham procedure in controls, failed to show significant BP reduction at 6 mo.

Nonobstructive angioscopy in patient with atherosclerotic renal artery stenosis

Few applications of angioscopy for evaluating atherosclerosis of the abdominal aorta have been described. We report the demonstration of atherosclerotic yellow plaque by nonobstructive angioscopy in a patient with left renal artery stenosis. Computed tomography angiography showed stenosis in one of the left renal arteries in a 65-year-old man who presented with renal impairment and hypertension. Invasive selective renal angiography indicated severe stenosis in the proximal portion of the inferior left renal arteries. Intravascular ultrasound demonstrated eccentric plaque with predominant low-density plaque with calcification as the culprit. Percutaneous transluminal renal angioplasty with stent implantation of the left renal artery was performed. Nonobstructive angioscopy demonstrated a grade 3 yellow culprit plaque at the proximal end of the stent, and grade 2 and grade 1 yellow plaques as the culprit plaques at the middle and distal portions of the artery, respectively. .

A reversible cause of 'end-stage renal disease': discrepant findings in serial duplex ultrasonograms in a suspected occlusion of a renal arterial bypass graft

Duplex ultrasonography may be inaccurate due to a number of variables in operator and patient characteristics. We describe a 40-year-old woman who presented with acute kidney injury after prior complex abdominal aortic surgery that had left her with an essentially solitary functional kidney. On the basis of normal Doppler findings, she was started on dialysis. Owing to high clinical suspicion and a failure of renal function to return, a second Doppler study was performed 3 weeks after the first, revealing the characteristic tardus-parvus waveform of renal artery stenosis. The patient underwent urgent renal arterial angioplasty and stent placement. She experienced an immediate increase in urinary output, required no further dialysis, and the creatinine improved to 1.7 mg/dL (her prior renal baseline). The case illustrates an important complication of abdominal aortic aneurysm repair, draws attention to a potential source of error in the Doppler measurement, and underscores the limitations of duplex ultrasonography for excluding renal artery stenosis in the presence of high pretest probability.

Stent revascularization restores cortical blood flow and reverses tissue hypoxia in atherosclerotic renal artery stenosis but fails to reverse inflammatory pathways or glomerular filtration rate

BACKGROUND

Atherosclerotic renal artery stenosis (ARAS) is known to reduce renal blood flow, glomerular filtration rate (GFR) and amplify kidney hypoxia, but the relationships between these factors and tubulointerstitial injury in the poststenotic kidney are poorly understood. The purpose of this study was to examine the effect of renal revascularization in ARAS on renal tissue hypoxia and renal injury.

METHODS AND RESULTS

Inpatient studies were performed in patients with ARAS (n=17; >60% occlusion) before and 3 months after stent revascularization, or in patients with essential hypertension (n=32), during fixed Na(+) intake and angiotensin converting enzyme/angiotensin receptors blockers Rx. Single kidney cortical, medullary perfusion, and renal blood flow were measured using multidetector computed tomography, and GFR by iothalamate clearance. Tissue deoxyhemoglobin levels (R(2)*) were measured by blood oxygen level-dependent MRI at 3T, as was fractional kidney hypoxia (percentage of axial area with R(2)*>30/s). In addition, we measured renal vein levels of neutrophil gelatinase-associated lipocalin, monocyte chemoattractant protein-1, and tumor necrosis factor-α. Pre-stent single kidney renal blood flow, perfusion, and GFR were reduced in the poststenotic kidney. Renal vein neutrophil gelatinase-associated lipocalin, tumor necrosis factor-α, monocyte chemoattractant protein-1, and fractional hypoxia were higher in untreated ARAS than in essential hypertension. After stent revascularization, fractional hypoxia fell (P<0.002) with increased cortical perfusion and blood flow, whereas GFR and neutrophil gelatinase-associated lipocalin, monocyte chemoattractant protein-1, and tumor necrosis factor-α remained unchanged.

CONCLUSIONS

These data demonstrate that despite reversal of renal hypoxia and partial restoration of renal blood flow after revascularization, inflammatory cytokines and injury biomarkers remained elevated and GFR failed to recover in ARAS. Restoration of vessel patency alone failed to reverse tubulointerstitial damage and partly explains the limited clinical benefit of renal stenting. These results identify potential therapeutic targets for recovery of kidney function in renovascular disease.

The Role of Sonography in Renal Artery Stenosis Evaluation and Stent Placement

A literature review has been conducted to demonstrate the role of duplex sonography in evaluating renal artery stenosis (RAS) as a screening method for patients prior to percutaneous transluminal renal artery stent (PTRAS) placement. The review also evaluates the role of ultrasound surveillance following PTRAS and establishes the overall influence of ultrasound on defining stent efficacy for managing hemodynamically significant renovascular disease. Recent studies have narrowed criteria for intervention through duplex sonographic assessment of RAS to better predict patient benefit and response to stent placement. Studies using sonographic parameters evaluating patients for renal artery stenosis, criteria-dependent stent placement, and postintervention follow-up have shown improved patient response, helping ensure effective and appropriate care in RAS management.

Screening for significant atherosclerotic renal artery stenosis with a regression model in patients undergoing transradial coronary angiography/intervention

OBJECTIVE

Early detection of atherosclerotic renal artery stenosis (ARAS) is clinically important with respect to blood pressure control, prevention of renal insufficiency, and even improving survival. We investigated whether the presence of significant ARAS (luminal diameter narrowing ≥70%) could be predicted using a logistic regression model before coronary angiography/intervention.

METHODS

Initially, we developed a logistic regression model for detecting significant ARAS based upon clinical and angiographic features and biochemical measurements in a cohort of 1813 patients undergoing transfemoral coronary and renal angiography. This model was then prospectively applied to an additional 495 patients who received transradial renal angiography to ascertain its predictive accuracy for the presence of significant ARAS.

RESULTS

Multivariate regression analysis revealed that older age (≥65 years), resistant hypertension, type 2 diabetes, creatinine clearance (Ccr) ≤60 ml/min, and multivessel coronary disease were independent predictors for significant ARAS. A logistic regression model for detecting ARAS by incorporating conventional risk factors and multivessel coronary disease was generated as: P/(1-P)=exp(-2.618+1.112[age≥65 years]+1.891[resistant hypertension]+0.453[type 2 diabetes]+0.587[Ccr≤60 ml/min]+2.254[multivessel coronary disease]). When this regression model was prospectively applied to the additional 495 patients undergoing transradial coronary and renal angiography, significant ARAS could be detected with a sensitivity of 81.2%, specificity of 88.9%, and positive and negative predictive accuracies of 53.8% and 96.7%, respectively.

CONCLUSIONS

The logistic regression model generated in this study may be useful for screening for significant ARAS in patients undergoing transradial coronary angiography/intervention.

Screening for carotid artery stenosis and renal artery stenosis in patients undergoing tunneled cuffed hemodialysis catheter placement

In this study, we noted the common risk factors with atherosclerosis and chronic renal disease. We, therefore, hypothesized that the placement of a dialysis catheter would be a useful marker in identifying populations at increased risk of vascular disease (carotid, renal, and aortic). To further explore this issue, we examined the results of duplex scanning of the carotid arteries and aortorenal arteries in patients undergoing dialysis catheter placement. Over 49 months, each of the 123 patients who underwent permanent tunneled dialysis catheter placement received a carotid duplex study. Twelve patients (9.8%) had ≥ 60% stenosis and 8 patients (6.5%) had 70% to 99% stenosis. Furthermore, 109 patients who underwent a aortorenal artery duplex study were also analyzed. The study population demonstrated a prevalence rate of 3.7% for abdominal aorta aneurysm (AAA) and 4.6% for renal artery stenosis (RAS). Based upon these data, we suggest performing routine carotid duplex scans in patients who will also receive dialysis catheter placement. However, the data did not support routine screening of AAA or RAS.

The incidence of renal artery stenosis in the patients referred for coronary artery bypass grafting

Multivessel coronary disease or peripheral arterial disease is the clinical clue to diagnosis of renal artery stenosis (RAS). RAS is considered equivalent to coronary artery disease in terms of cardiovascular risk. In this study, we evaluated the incidence of RAS in the patients who were proposed to undergo coronary artery bypass grafting (CABG). Diagnostic evaluations of coronary arteriography and renal artery angiography were performed during the same procedure; the patients who were proposed for CABG in terms of CAD anatomy and clinical manifestation were enrolled. RAS was evaluated and a diameter stenosis of ≥50% was considered as significant RAS; significant RAS patients were divided into five groups. The five groups of RAS were as follows: (1) unilateral RAS ≥50–70%, (2) unilateral RAS ≥70%, (3) bilateral RAS ≥50–70%, (4) one-renal-artery stenosis ≥50–70%, contralateral RAS ≥70%, and (5) bilateral renal artery stenosis ≥70%. A total of 151 patients were enrolled, and RAS (≥50% stenosis in either or both renal arteries) was identified in 47.02% (71/151) patients. Unilateral RAS ≥50–70% was identified in 16.6% (25/151) patients, unilateral RAS ≥70% in 4.6% (7/151) patients, bilateral RAS ≥50–70% in 7.9% (12/151) patients, one-renal-artery stenosis ≥50–70% and contralateral RAS ≥70% in 7.9% (12/151) patients, and bilateral RAS ≥70% was in 9.9%(15/151) patients. The incidence of RAS was 29.03% (18/62) in patients aged ≤60 years, 60% (36/60) in patients aged >60 and ≤70 years, and 58.62% (17/29) in patients aged >70 years. The incidence of RAS was significantly higher in patients aged >60 - ≤70, and >70 years than patients aged ≤60 years (P = 0.001 and P = 0.007, respectively). There was a trend that the incidence of RAS in patients with hypertension [HTN, 50.40% (64/127)] was higher than those without HTN (29.17%, 7/24), with P = 0.056. The incidence of RAS was 47.02% in patients who were proposed for CABG; bilateral RAS of ≥70% was 9.9%. Older age and HTN were associated with RAS in patients who were referred for CABG. This study indicates that the incidence of RAS was high in the patients referred for CABG, and the renal function should be taken care of.

Influence and critique of the ASTRAL and CORAL Trials

Optimal management of renal artery atherosclerotic occlusive disease has been widely debated and studied. Although the accepted invasive treatment has evolved into favoring balloon angioplasty and stenting, the indications for intervention or medical therapy have not been universally agreed upon. The Angioplasty and Stenting for Renal Artery Lesions (ASTRAL) trial was conducted to answer the question of whether medical therapy or angioplasty and stenting is the best treatment for hemodynamically significant renal artery stenosis. However, the ASTRAL trial's study design was faulty and therefore did not provide conclusive evidence to answer the question. The Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial was designed to answer the same question as to which treatment (medical or angioplasty and stent) is best for renal artery stenosis, and its methodologies took into consideration the weaknesses of the ASTRAL trial. Results are soon to be released.

Arterial interventions for renovascular hypertension

Renovascular hypertension is a major cause of secondary hypertension. It affects relatively younger patients. The unifying pathology is renal artery stenosis. The most common cause is atherosclerosis accounting for about 90% of cases with fibromuscular dysplasia being the second most common cause. Both of these are amenable to percutaneous interventional therapy. With the advent of new medical therapies, the control of blood pressure has improved significantly. In well-selected patients, renal arterial intervention has a good outcome. The intervention includes renal angioplasty and stenting. In this article, the authors review the role of percutaneous intervention and the techniques involved with renal angioplasty and stenting for the treatment of renovascular hypertension.

Atherosclerotic renal artery stenosis--diagnosis and treatment

Renal artery stenosis (RAS) is characterized by a heterogeneous group of pathophysiologic entities, of which fibromuscular dysplasia and atherosclerotic RAS (ARAS) are the most common. Whether and which patients should undergo revascularization for ARAS is controversial. The general consensus is that all patients with ARAS should receive intensive medical treatment. The latest randomized clinical trials have increased confusion regarding recommendations for revascularization for ARAS. Although revascularization is not indicated in all patients with ARAS, experts agree that it should be considered in some patients, especially those with unstable angina, unexplained pulmonary edema, and hemodynamically significant ARAS with either worsening renal function or with difficult to control hypertension. A search of the literature was performed using PubMed and entering the search terms renal artery stenosis, atherosclerotic renal artery stenosis, and renal artery stenosis AND hypertension to retrieve the most recent publications on diagnosis and treatment of ARAS. In this review, we analyze the pathways related to hypertension in ARAS, the optimal invasive and noninvasive modalities for evaluating the renal arteries, and the available therapies for ARAS and assess future tools and algorithms that may prove useful in evaluating patients for renal revascularization therapy.

Revascularization of swine renal artery stenosis improves renal function but not the changes in vascular structure

Renal revascularization by percutaneous transluminal angioplasty improves blood pressure and stenotic kidney function in selected groups of patients, but the reversibility of intrarenal and microvascular remodeling remains unknown. Here, we tested the hypothesis that renal angioplasty improves the function and structure of renal microcirculation in experimental chronic renal artery stenosis. Stenotic kidney function, hemodynamics, and endothelial function were assessed in vivo in pigs after 10 weeks of unilateral renal artery stenosis. Renal microvascular remodeling, angiogenic pathways, and fibrosis were measured ex vivo. Angioplasty and stenting carried out 4 weeks before measurement decreased blood pressure, improved glomerular filtration rate, and improved microvascular endothelial function. It also promoted the expression of angiogenic factors and decreased renal apoptosis due to stenosis, compared with a sham intervention. The spatial density of renal microvessels, however, was partially improved after angioplasty. Renal blood flow was incompletely restored compared with the kidneys of sham-treated animals, as was interstitial fibrosis. Renal microvascular media-to-lumen ratio remained unchanged by angioplasty. Thus, our study shows that revascularization of a stenotic renal artery restores the glomerular filtration rate and renal endothelial function 4 weeks later. Renal hemodynamics and structure, however, are incompletely resolved.