Management of renovascular disease: a review of renal artery stenting in ten studies

Use of percutaneous transluminal renal angioplasty in atherosclerotic renal artery stenosis: a systematic review and meta-analysis

OBJECTIVE

For patients with atherosclerotic renal artery stenosis (ARAS), the role of percutaneous transluminal renal angioplasty (PTRA) remains inconclusive. This study aimed to comparatively evaluate the benefits of best medical therapy (BMT) plus PTRA and BMT alone in treating ARAS.

METHODS

We performed a systematic review and meta-analysis, and searched for all randomized, controlled trials that reported patients with ARAS. The effectiveness and safety in the BMT plus PTRA and BMT alone groups were estimated, taking into account hypertension, stroke, renal events, cardiac events, and mortality.

RESULTS

Nine randomized, controlled trials involving 2309 patients were included. In the BMT plus PTRA group, the incidence of refractory hypertension was significantly lower compared with that in the BMT alone group (odds ratio 0.09; 95% confidence interval 0.01, 0.70). However, there were no significant differences in the rates of stroke, renal events, cardiac events, cardiac mortality, and all-cause mortality between the two groups.

CONCLUSIONS

PTRA plus BMT improves blood pressure in patients with ARAS, but there is insufficient evidence for this therapy in improving stroke, renal events, cardiac events, and cardiac and all-cause mortality.

When and How Should We Revascularize Patients With Atherosclerotic Renal Artery Stenosis?

Atherosclerotic renal artery stenosis is the leading cause of secondary hypertension and may lead to resistant (refractory) hypertension, progressive decline in renal function, and cardiac destabilization syndromes (pulmonary edema, recurrent heart failure, or acute coronary syndromes) despite guideline-directed medical therapy. Although randomized controlled trials comparing medical therapy with medical therapy and renal artery stenting have failed to show a benefit for renal artery stenting, according to comparative effectiveness reviews by the Agency for Healthcare Research and Quality, the trials may not have enrolled patients with the most severe atherosclerotic renal artery stenosis, who would be more likely to benefit from renal stenting. Because of limitations of conventional angiography, it is critical that the hemodynamic severity of moderately severe (50% to 70%) atherosclerotic renal artery stenosis lesions be confirmed on hemodynamic measurement. The authors review techniques to optimize patient selection, to minimize procedural complications, and to facilitate durable patency of renal stenting. The authors also review the current American College of Cardiology and American Heart Association guidelines and the Society for Cardiovascular Angiography and Interventions appropriate use criteria as they relate to renal stenting.

Successful Depressor Effect Concomitant with Complete Normalization of High Renin and Aldosterone Profile by Percutaneous Transluminal Renal Angioplasty in a Patient with Acute Exacerbated Heart Failure with Preserved Ejection Fraction

Patient: Male, 59

Final Diagnosis: Renovascular hypertension

Symptoms: Dyspnea

Medication: —

Clinical Procedure: Percutaneous transluminal renal angioplasty

Specialty: Cardiology

3D-Printed Sugar-Based Stents Facilitating Vascular Anastomosis

Microvascular anastomosis is a common part of many reconstructive and transplant surgical procedures. While venous anastomosis can be achieved using microvascular anastomotic coupling devices, surgical suturing is the main method for arterial anastomosis. Suture-based microanastomosis is time-consuming and challenging. Here, dissolvable sugar-based stents are fabricated as an assistive tool for facilitating surgical anastomosis. The nonbrittle sugar-based stent holds the vessels together during the procedure and are dissolved upon the restoration of the blood flow. The incorporation of sodium citrate minimizes the chance of thrombosis. The dissolution rate and the mechanical properties of the sugar-based stent can be tailored between 4 and 8 min. To enable the fabrication of stents with desirable geometries and dimensions, 3D printing is utilized to fabricate the stents. The effectiveness of the printed sugar-based stent is assessed ex vivo. The fabrication procedure is fast and can be performed in the operating room.

Minimally invasive percutaneous transluminal renal artery stenting

BACKGROUND

Minimally invasive percutaneous transluminal renal artery stenting (MIPTRS) is a method that prevents complications to the greatest extent possible. The present study aimed to investigate the safety and efficacy of MIPTRS performed in cases of renal artery stenosis with an estimated glomerular filtration rate (eGFR)≤45mL/min.

METHODS

Cases of patients who underwent MIPTRS at our hospital between December 2010 and June 2015 in whom eGFR was ≤45mL/min were retrospectively analysed. MIPTRS was performed as follows: 1) using a 4Fr sheathless guiding catheter in a trans-radial approach and 2) using a guiding catheter non-touch technique. The amount of contrast agent used was maintained at ≤10mL with 3) carbon dioxide enhancement and 4) intravascular ultrasound guide stenting, and 5) a distal protection device was used.

RESULTS

MIPTRS was performed in 22 patients (32 lesions). The pre-MIPTRS creatinine level and eGFR were 2.01±0.88mg/dL and 29.2±9.0mL/min/1.73m², respectively. On postoperative day 2, they were 1.78±0.73mg/dL and 35.1±12.3mL/min/1.73m²; at 1month after the procedure, they were 1.80±0.74mg/dL and 33.3±12.3mL/min/1.73m². Creatinine level did not change significantly, but eGFR was significantly elevated after versus before the procedure, both 2days later (p<0.01) and 1month later (p<0.05).

CONCLUSION

The results of this study demonstrated the usefulness of MIPTRS for protecting renal function. This method can be safely used in patients with decreased renal function.

Renal artery stenting for atherosclerotic renal artery stenosis identified in patients with coronary artery disease: Does captopril renal scintigraphy predict outcomes?

The authors evaluated the effectiveness of percutaneous renal revascularization (PRR) with stenting for the treatment of atherosclerotic renal artery stenosis (ARAS) in patients with coronary artery disease and the usefulness of captopril renal scintigraphy for predicting clinical outcomes after PRR. Sixty-four consecutive patients, referred for evaluation of suspected ARAS, after coronary angiography, underwent baseline captopril renal scintigraphy followed by renal angiography. Forty-four patients (68.7%) were diagnosed with a significant ARAS≥ 60% and were treated with PRR plus medical therapy. Twenty-four months after PRR, 86.4% and 73.3% of patients showed a hypertension and renal benefit, respectively. Captopril renal scintigraphy positivity had moderate sensitivity and high specificity in predicting a hypertension and renal benefit. In patients with ARAS≥ 70%, the sensitivity and specificity were 100% for both a hypertension and renal benefit.PRR for ARAS conferred a substantial benefit in patients with a high coronary artery disease burden. Captopril renal scintigraphy was highly accurate in predicting clinical outcomes.

Drug-eluting stents versus bare metal stents for the prevention of restenosis in patients with renovascular disease

AIMS

The aim of this study was to assess the impact of drug-eluting stents (DES) compared to bare metal stents (BMS) for the endovascular treatment of atherosclerotic renal artery stenosis (ARAS).

METHODS AND RESULTS

We retrospectively evaluated all of our endovascular BMS and DES implantations performed in de novo ARAS between 2000 and 2014 at our institution. The occurrence of in-stent restenosis (ISR) detected by ultrasound or angiography, kidney function, blood pressure (BP), and the number of antihypertensive drugs were analysed as endpoints. Overall, 338 renal arteries were treated in 298 patients. BMS were implanted in 163 (48%), and DES in 175 lesions (52%). Of the 175 lesions treated with DES, 55 (31%) were treated with a BMS-in-DES hybrid technique. For reasons of comparability, only lesions treated with balloon sizes of 4-6.5 mm were included in the final analysis. After 12 months, the rate of ISR >50% was 18.6% in the BMS group and 7.2% in the DES group (p=0.031). None of the BMS-in-DES-treated (hybrid) lesions developed ISR (hybrid technique vs. BMS only p=0.008, hybrid technique vs. DES only p=0.034). Systolic BP and number of antihypertensive drugs remained unchanged in the BMS group but declined in the DES group (p=0.02). Renal function significantly deteriorated in the BMS group (p=0.03) but did not change significantly in the DES group (p=0.188).

CONCLUSIONS

DES were superior to BMS in preventing ISR. Overall, the BMS-in-DES-technique (hybrid) achieved the lowest risk for ISR.

Renal Artery Stenosis: Optimal Therapy and Indications for Revascularization

Atherosclerotic renal artery stenosis (ARAS) is associated with increased cardiovascular risk and overall mortality. Manifestations of ARAS include resistant or malignant hypertension, progressive deterioration of renal function, and cardiac dysfunction syndromes of flash pulmonary edema and angina. Diagnosis rests upon non-invasive studies such as duplex ultrasonography and is confirmed using invasive renal arteriography. Regardless of the severity of ARAS, management of this entity has been a topic of contentious debate. For over two decades, the use of percutaneous revascularization to treat ARAS has been studied with various clinical trials. Though case series seem to demonstrate favorable clinical response to revascularization, the overwhelming majority of randomized clinical trials have not mirrored a robust outcome. In these trials, poor correlation is noted between the reduction of stenosis and the improvement of renovascular hypertension and glomerular filtration rate, and decrease in cardiovascular outcomes and mortality. With dichotomizing results, the explanation for these discrepant findings has been attributed to improper trial design and inappropriate patient selection. An overview of the treatment options available will be provided, with a focus on the methodology and design of clinical trials investigating the efficacy of percutaneous revascularization. Emphasis is placed on appropriate patient selection criteria, which may necessitate the use of hemodynamic lesion assessment and clinical correlation based on individualized care. When clinical equipoise exists between optimal medical therapy and revascularization, the current paradigm supports ongoing medical therapy as the treatment of choice. However, renal artery stenting remains a viable therapeutic option for those who continue to have clinical syndromes consistent with renal hypoperfusion while adequately treated with optimal medical therapy. Despite observational studies suggesting clinical benefit for this specific patient population, there remains a paucity of randomized clinical trial data. Further trials targeting the patients who are inadequately treated with optimal medical therapy need to be undertaken to confirm the efficacy of revascularization.

Current approaches to atherosclerotic obstructive renal artery stenosis

Increased lifespan in the last few decades has substantially changed the scenario for renal artery stenosis. Indeed, because older populations show a higher prevalence of atherosclerotic disease, the incidence of atheromatous renal artery stenosis has also increased. Intuitively, one could surmise that stenosis removal should void both the hypertension and the kidney damage resulting from the obstructive stenosis. Surprisingly, a number of important clinical trials have failed to show the reversion seen in experimental models. The reasons for these differences may be linked to chronicity and inflammation associated with the atherosclerotic lesion. However, the failure to obtain a favorable response may also be related to abnormalities in the contralateral kidney. Indeed, this apparently normal kidney should work to compensate the hemodynamic effects of the ipsilateral stenosed kidney. Instead, structure and function in the contralateral kidney can be altered in renal artery stenosis to the point that this nonstenotic kidney may sustain both, hypertension and progressive kidney disease. Certainly, comparing the effects of clip removal in the Goldblatt model to angioplasty in clinical settings with atherosclerotic lesions may be totally inappropriate. Nevertheless, there remain certain clinical situations such as bilateral renal arterial disease, congestive heart failure, and progressive renal failure, where angioplasty may be an alternative. These approaches however are yet to be tested.

Safety and efficacy of carbon dioxide and intravascular ultrasound-guided stenting for renal artery stenosis in patients with chronic renal insufficiency

We evaluated the feasibility, safety, and mid-term outcomes of renal artery stenting using carbon dioxide (CO₂) digital subtraction angiography and intravascular ultrasound (IVUS) for patients with renal insufficiency and significant atherosclerotic renal artery stenosis (RAS). Eighteen consecutive patients with chronic renal insufficiency underwent renal artery stenting under the guidance of CO₂ angiography and IVUS without contrast media. Renal function and blood pressure were assessed pre- and postintervention. A total of 27 de novo RAS in 18 patients (15 males; mean age: 72 ± 9 years) with renal insufficiency were treated by renal artery stenting with the combined use of the CO₂ angiography and IVUS without any procedural complications. Although the mean serum creatinine concentration preprocedure and 6 months after treatment did not change (2.7 ± 1.0-2.4 ± 1.1 mg/dL), blood pressure significantly decreased 6 months after stenting (158 ± 10-147 ± 11 mm Hg, P < .01).

From the 1990s to CORAL (Cardiovascular Outcomes in Renal Atherosclerotic Lesions) trial results and beyond: does stenting have a role in ischemic nephropathy?

The prevalence of atherosclerotic renal artery stenosis is high, ∼7% in individuals older than 65 years and ∼50% in patients with diffuse arterial disease, and it is increasingly frequent in an aging population. About 10% to 15% of atherosclerotic renal artery stenosis cases lead to the development of resistant hypertension and/or ischemic nephropathy. The management of ischemic nephropathy may include medical therapy and/or revascularization. In the past, revascularization required surgical bypass or endarterectomy, accompanied by the morbidity and mortality associated with a major surgical procedure. During the last few decades, less invasive endovascular procedures such as percutaneous transluminal renal artery angioplasty with stent placement have become available. At the same time, new antihypertensive and cardiovascular drugs have been developed, which may preclude revascularization, at least in some cases. The indications of each of these therapeutic options have changed over time. This review offers a temporal perspective on the course of technical and scientific advances and the accompanying change in clinical practice for the treatment of ischemic nephropathy. The latest randomized clinical trials, including the CORAL (Cardiovascular Outcomes in Renal Atherosclerotic Lesions) trial, the largest on the subject, as well as a meta-analysis of these studies, have indicated that the best approach is medical therapy alone. There is evidence that revascularization brings no additional benefit, at least in low-risk and stable atherosclerotic renal artery stenosis. High-risk patients, especially those with recurrent flash pulmonary edema, could benefit from percutaneous transluminal renal artery angioplasty and stent placement, but there is no definitive evidence and the treatment choice should take into account the risks and potential benefits of the procedure.

Transcatheter renal interventions: a review of established and emerging procedures

Catheter-based interventions play an important role in the multidisciplinary management of renal pathology. The array of procedures available to interventional radiologists (IRs) includes established techniques such as angioplasty, stenting, embolization, thrombolysis, and thrombectomy for treatment of renovascular disease, as well as embolization of renal neoplasms and emerging therapies such as transcatheter renal artery sympathectomy for treatment of resistant hypertension. Here, we present an overview of these minimally invasive therapies, with an emphasis on interventional technique and clinical outcomes of the procedure.

SCAI expert consensus statement for renal artery stenting appropriate use

The pathophysiology of atherosclerotic renal artery stenosis (RAS) includes activation of the renin-angiotensin-aldosterone axis with resultant renovascular hypertension. Renal artery stenting has emerged as the primary revascularization strategy in most patients with hemodynamically significant atherosclerotic RAS. Despite the frequency with which hemodynamically significant RAS is observed and high rates of technical success of renal artery stenting, there remains considerable debate among experts regarding the role of medical therapy versus revascularization for renovascular hypertension. Modern, prospective, multicenter registries continue to demonstrate improvement in systolic and diastolic blood pressure with excellent safety profiles in patients with RAS. Modern randomized, controlled clinical trials of optimal medical therapy versus renal stenting particularly designed to demonstrate preservation in renal function after renal artery stenting have demonstrated limited benefit. However, these trials frequently excluded patients that may benefit from renal artery stenting. This document was developed to guide physicians in the modern practical application of renal stenting, to highlight the current limitations in the peer-reviewed literature, to suggest best-practices in the performance of renal stenting and to identify opportunities to advance the field.

Management of Renal Arterial Disease

Severe atherosclerotic renal artery stenosis can manifest as treatment-resistant hypertension, ischemic nephropathy and/or cardiac disturbance syndromes of recurrent flash pulmonary edema and refractory angina. Renal artery revascularization can dramatically impact patient outcome. However, patient selection for revascularization can be challenging. Renal artery stenting is most commonly used for renal revascularization and is a safe procedure when performed in carefully selected patients. This review addresses the pathophysiology of renal artery stenosis and the data supporting revascularization in such patients.

Management of atherosclerotic renovascular disease after Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL)

Many patients with occlusive atherosclerotic renovascular disease (ARVD) may be managed effectively with medical therapy for several years without endovascular stenting, as demonstrated by randomized, prospective trials including the Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial, the Angioplasty and Stenting for Renal Artery Lesions (ASTRAL) trial and the Stent Placement and Blood Pressure and Lipid-Lowering for the Prevention of Progression of Renal Dysfunction Caused by Atherosclerotic Ostial Stenosis of the Renal Artery (STAR) and ASTRAL. These trials share the limitation of excluding subsets of patients with high-risk clinical presentations, including episodic pulmonary edema and rapidly progressing renal failure and hypertension. Although hemodynamically significant, ARVD can reduce renal blood flow and glomerular filtration rate; adaptive mechanisms preserve both cortical and medullary oxygenation over a wide range of vascular occlusion. Progression of ARVD to severe vascular compromise eventually produces cortical hypoxia, however, associated with active inflammatory cytokine release and cellular infiltration of the renal parenchyma. In such cases ARVD produces a loss of glomerular filtration rate that no longer is reversible simply by restoring vessel patency with technically successful renal revascularization. Each of these trials reported adverse renal functional outcomes ranging between 16 and 22% over periods of 2-5 years of follow-up. Blood pressure control and medication adjustment may become more difficult with declining renal function and may prevent the use of angiotensin receptor blocker and angiotensin-converting enzyme inhibitors. The objective of this review is to evaluate the current management of ARVD for clinical nephrologists in the context of recent randomized clinical trials and experimental research.

Revascularization as a treatment to improve renal function

An aging atherosclerosis-prone population has led to an increase in the prevalence of atherosclerotic renovascular disease (ARVD). Medical management of this disease, as with other atherosclerotic conditions, has improved over the past decade. Despite the widespread availability of endovascular revascularization procedures, there is inconsistent evidence of benefit in ARVD and no clear consensus of opinion as to the best way to select suitable patients for revascularization. Several published randomized controlled trials have attempted to provide clearer evidence for best practice in ARVD, but they have done so with varying clarity and success. In this review, we provide an overview of ARVD and its effect on renal function. We present the currently available evidence for best practice in the management of patients with ARVD with a particular focus on revascularization as a treatment to improve renal function. We provide a brief overview of the evidence for revascularization in other causes of renal artery stenosis.

Renal angioplasty for atherosclerotic renal artery stenosis: Cardiologist's perspective

Atherosclerotic renal artery stenosis (ARAS) is frequently associated with concomitant coronary and peripheral arterial disease with a significant impact on cardiovascular morbidity and mortality. Renal angioplasty of ARAS is more challenging because of increased incidence of technical failures, complications, and restenosis; while there is barely perceptible control of hypertension and only marginal improvement in renal function. This is because most of the patient population in recent randomized trials had unmanifested or clinically silent renovascular disease. Manifestations of RAS should be looked for and incorporated in the management plan particularly before deciding for revascularization. In the absence of clinical manifestation like renovascular hypertension, ischemic nephropathy, left ventricular failure, or unstable coronary syndromes; mere presence of RAS is analogous to presence of concomitant peripheral arterial disease which increases risk of adverse coronary events. Dormant-RAS in the absence of any manifestations can be managed with masterly inactivity. Chronological sequence of events and clinical condition of the patient help in decision making by identifying progressive renovascular disease. Selecting patients for renal artery stenting who actually will benefit from revascularization shall also decrease the unnecessary complications inherent with any interventional procedure. The present review is an attempt to analyze the current view on the diagnostic and management issues more specifically about the need and rationale behind angioplasty.

Treatment of atheromatous renal artery in-stent restenosis in 51 patients

OBJECTIVE

To evaluate our treatment of renal artery in-stent restenosis.

PATIENTS AND METHODS

Monocentric retrospective study of 53 cases of restenosis and two occlusions in 51 patients detected via systematic follow-up with imaging (72.5%) and/or deterioration of kidney function (5.9%) and/or blood pressure failure (54.9%), 15.7 months (5-121) after implantation, giving rise to 49 recalibrations via a balloon and five additional stentings. Analysis of the technical results, the effects on blood pressure and kidney function after repeated revascularizations.

RESULTS

Secondary permeability of 38 arteries (63.2%) after 12.4 months (3-64) with 14 second restenoses; 33.3% after redilation with a balloon, 60% after renewed stenting, more common in smokers (P=0.02), in case of peripheral arterial disease (P=0.02), ostial location (P=0.049) and kidney function impairment at the time of diagnosis of the restenosis (P=0.012). After 12.7 months (3-64) post-revascularization, kidney function was improved in 30% of patients and stabilised in 50% of patients. Treatment of second restenoses: one failure (7.1%), nine dilations with a balloon, three cutting balloon, one second stent. Treatment of third restenoses: 71.4% treated with a balloon (2), cutting balloon (2) or coated stent (DES) (1); then permeability at a later point in time: 50%.

CONCLUSION

The treatment of repeated restenoses with conventional techniques is of imperfect efficacy, and currently remains un-codified.

Percutaneous revascularization for ischemic nephropathy: the past, present, and future

Occlusion of the renal arteries can threaten the viability of the kidney when severe, in addition to accelerating hypertension and circulatory congestion. Renal artery stenting procedures have evolved from a treatment mainly for renovascular hypertension to a maneuver capable of recovering threatened renal function in patients with “ischemic nephropathy” and improving management of congestive heart failure. Improved catheter design and techniques have reduced, but not eliminated hazards associated with renovascular stenting. Expanded use of endovascular stent grafts to treat abdominal aortic aneurysms has introduced a new indication for renal artery stenting to protect the renal circulation when grafts cross the origins of the renal arteries. Although controversial, prospective randomized trials to evaluate the added benefit of revascularization to current medical therapy for atherosclerotic renal artery stenosis until now have failed to identify major benefits regarding either renal function or blood pressure control. These studies have been limited by selection bias and have been harshly criticized. While studies of tissue oxygenation using blood oxygen level dependent (BOLD) MR establish that kidneys can adapt to reduced blood flow to some degree, more severe occlusive disease leads to cortical hypoxia associated with microvascular rarefication, inflammatory injury and fibrosis. Current research is directed toward identifying pathways of irreversible kidney injury due to vascular occlusion and to increase the potential for renal repair after restoring renal artery patency. The role of nephrologists likely will focus upon recognizing the limits of renal adaptation to vascular disease and identifying kidneys truly at risk for ischemic injury at a time point when renal revascularization can still be of benefit to recovering kidney function.

Revascularization in renal artery stenosis

The predominant cause of renal artery stenosis (RAS) is atherosclerosis. Clinical manifestations of atherosclerotic RAS are both direct (hypertension and kidney dysfunction) and indirect (increased cardiovascular events and mortality). However, in many cases, atherosclerotic RAS seems to be an incidental finding with no discernable effects. Antihypertensive medications such as renin-angiotensin-aldosterone system inhibitors, along with statins and aspirin, have significantly improved the medical treatment of atherosclerotic RAS. However, revascularization is still advocated in a variety of clinical settings such as the preservation of renal function, recurrent episodes of "flash" pulmonary edema, and in patients with refractory hypertension. Current management guidelines indicate "resistant hypertension" as an indication for renal artery revascularization. A large number of observational studies support revascularization for both control of high blood pressure and/or preservation of renal function. Unfortunately, the favorable effects of revascularization on these end points seen in the observational studies were not reproduced in randomized controlled trials compared to medical therapy alone. The ability for revascularization to improve control of congestive heart failure or to prevent hard cardiovascular end points (eg, myocardial infarction or stroke) has not been tested in the randomized clinical trials published to date. Hence, the efficacy of intervention remains controversial, which poses a dilemma, especially given the large number of elderly patients with resistant systolic hypertension.

Adipose tissue-derived mesenchymal stem cells improve revascularization outcomes to restore renal function in swine atherosclerotic renal artery stenosis

Reno-protective strategies are needed to improve renal outcomes in patients with atherosclerotic renal artery stenosis (ARAS). Adipose tissue-derived mesenchymal stem cells (MSCs) can promote renal regeneration, but their potential for attenuating cellular injury and restoring kidney repair in ARAS has not been explored. We hypothesized that replenishment of MSC as an adjunct to percutaneous transluminal renal angioplasty (PTRA) would restore renal cellular integrity and improve renal function in ARAS pigs. Four groups of pigs (n = 7 each) were studied after 16 weeks of ARAS, ARAS 4 weeks after PTRA and stenting with or without adjunct intrarenal delivery of MSC (10 × 10(6) cells), and controls. Stenotic kidney blood flow (renal blood flow [RBF]) and glomerular filtration rate (GFR) were measured using multidetector computer tomography (CT). Renal microvascular architecture (micro-CT), fibrosis, inflammation, and oxidative stress were evaluated ex vivo. Four weeks after successful PTRA, mean arterial pressure fell to a similar level in all revascularized groups. Stenotic kidney GFR and RBF remained decreased in ARAS (p = .01 and p = .02) and ARAS + PTRA (p = .02 and p = .03) compared with normal but rose to normal levels in ARAS + PTRA + MSC (p = .34 and p = .46 vs. normal). Interstitial fibrosis, inflammation, microvascular rarefaction, and oxidative stress were attenuated only in PTRA + MSC-treated pigs. A single intrarenal delivery of MSC in conjunction with renal revascularization restored renal hemodynamics and function and decreased inflammation, apoptosis, oxidative stress, microvascular loss, and fibrosis. This study suggests a unique and novel therapeutic potential for MSC in restoring renal function when combined with PTRA in chronic experimental renovascular disease.

The effect of revascularization of renal artery stenosis on renal perfusion in patients with atherosclerotic renovascular disease

BACKGROUND

Only a small fraction of patients with atherosclerotic renovascular disease (ARVD) treated with revascularization have improved renal function after the procedure. It has been suggested that this may be due to effects of renal microvascular disease. Our aim was to measure the effect of renal artery stenosis (RAS) revascularization on renal perfusion in patients with renovascular disease.

METHODS

Seventeen renovascular disease patients were treated by dilatation of unilateral (N = 8) or bilateral (N = 9) RAS (N = 23 kidneys), mainly because of uncontrolled or refractory hypertension. The patients were studied before and after (103 ± 29 days) the procedure. Renal perfusion was measured using quantitative positron emission tomography (PET) perfusion imaging.

RESULTS

Although renal perfusion correlated inversely with the degree of RAS in patients with renovascular disease, it did not change after revascularization.

CONCLUSIONS

Our data support the notion of former clinical trials that angiographic severity of RAS does not determine the response to revascularization. Quantitative PET perfusion imaging is a promising tool to noninvasively measure renal perfusion for the assessment of physiological impact of RAS.

Secondary arterial hypertension: improvements in diagnosis and management in the last 10 years

The diagnosis and management of secondary hypertension has improved in the last decade as a result of the advances in the acknowledgment of some physiopathologic mechanisms and mainly by the development of new diagnostic methods. Furthermore, the treatment of some types of secondary hypertension may be solved by noninvasive techniques. Hypertension of renal and renovascular origin, coarctation of the aorta, primary hyperaldosteronism, and adrenal medullary tumors are analyzed. The main results of some relevant studies on diagnostic and treatment of those diseases are presented. Also, some experimental methods are mentioned, taking into account the possibility of clinical use in the near future.

Atherosclerotic renal artery stenosis and renal artery stenting: an evolving therapeutic option

Atherosclerotic renal artery stenosis is a common clinical problem for which the optimal therapeutic strategy remains to be defined. However, renal artery stenting procedures have significantly increased as one approach to treat this clinical problem. Despite improvements in device design and technical performance of the procedure, the benefits and results of randomized clinical trials of renal artery stenting as a therapy remain confusing. Understanding the epidemiology, pathophysiology and natural history of renal artery stenosis are central to improving the outcomes of renal artery stenting. Developing both noninvasive and invasive predictive tools to better identify which patient will respond to renal revascularization will also be beneficial. In this article, we will present an overview of atherosclerotic renal artery disease. The results of renal artery stenting will be discussed and from this, the available noninvasive and invasive tools available to assess the clinical and hemodynamic significance of renal artery stenosis will be presented.

Dramatic improvement of rapidly progressing acute renal failure and severe hypertension after bilateral renal artery stenting

In this case report, we describe an 83-year-old man with bilateral renal artery stenosis who had rapidly progressing acute renal failure and severe hypertension. These conditions improved dramatically after bilateral renal artery stenting. Renal artery stenosis can cause renal failure, hypertension, and heart failure, leading to a poorer life prognosis. If renal artery stenosis is found as a cause of acute renal failure, severe hypertension, or heart failure, it is useful to perform revascularization as soon as possible. Revascularization by stenting has a high success rate and is expected to improve the condition remarkably.

Clinical efficacy of percutaneous renal revascularization with stent placement in hypertension among patients with atherosclerotic renovascular diseases

AIM

The aim was to assess the effect of renal angioplasty with stent on systolic, diastolic, and mean arterial blood pressure (MAP) in awake and sleep time with ambulatory blood pressure (ABP) monitoring (Holter monitoring).

MATERIALS AND METHODS

Patients with angiographically proven atherosclerotic renal artery stenosis (RAS) were referred to the Angiography Department of Imam Hospital for intervention during a 1-year period from June 2008 to December 2009. Primary stent placement was attempted by a single operator in 27 severe RAS cases although 1 case was omitted from the study because of technical failure. Pre- and postprocedure creatinine levels, ejection fraction (EF), history of diabetes mellitus (DM), and ABP were obtained. Twenty-six (17 men, 9 women; average age, 62.6 years; age range, 90-21 years) consecutive patients participated in the study.

RESULTS

All patients had severe hypertension resistant to multiple medications; 10 patients had impaired renal function (serum creatinine level greater than 130 µmol/L). A total of 3 (11.5%) patients had congestive heart failure, and 10 (37.7%) were diabetic. Hypertension was cured in 1 (4%) patient, had improved in 23 (88.4%) patients, and had failed to respond to treatment in 2 (7.6%). Serum creatinine decreased significantly from 1.46 ± 0.89 to 1.35 ± 0.61 mg/dL (P<0.05).

CONCLUSION

Percutaneous transluminal angioplasty for atheromatous RAS rarely cures hypertension, but improved blood pressure control is often achieved.

Renovascular hypertension and ischemic nephropathy

Renovascular disease remains among the most prevalent and important causes of secondary hypertension and renal dysfunction. Many lesions reduce perfusion pressure including fibromuscular diseases and renal infarction, but most are caused by atherosclerotic disease. Epidemiologic studies establish a strong association between atherosclerotic renal-artery stenosis (ARAS) and cardiovascular risk. Hypertension develops in patients with renovascular disease from a complex set of pressor signals, including activation of the renin-angiotensin system (RAS), recruitment of oxidative stress pathways, and sympathoadrenergic activation. Although the kidney maintains function over a broad range of autoregulation, sustained reduction in renal perfusion leads to disturbed microvascular function, vascular rarefaction, and ultimately development of interstitial fibrosis. Advances in antihypertensive drug therapy and intensive risk factor management including smoking cessation and statin therapy can provide excellent blood pressure control for many individuals. Despite extensive observational experience with renal revascularization in patients with renovascular hypertension, recent prospective randomized trials fail to establish compelling benefits either with endovascular stents or with surgery when added to effective medical therapy. These trials are limited and exclude many patients most likely to benefit from revascularization. Meaningful recovery of kidney function after revascularization is limited once fibrosis is established. Recent experimental studies indicate that mechanisms allowing repair and regeneration of parenchymal kidney tissue may lead to improved outcomes in the future. Until additional staging tools become available, clinicians will be forced to individualize therapy carefully to optimize the potential benefits regarding both blood pressure and renal function for such patients.

Prevalence of renal artery stenosis in flash pulmonary oedema: determination using gadolinium-enhanced MRA

PURPOSE

The primary purpose was to determine the prevalence of renal artery stenosis (RAS) in patients presenting with acute ("flash") pulmonary oedema (FPE), without identifiable cause using contrast-enhanced magnetic resonance angiography (CE-MRA) of renal arteries. A secondary goal was to correlate clinical parameters at presentation with the presence or absence of RAS.

MATERIALS AND METHODS

Patients presenting with acute pulmonary oedema without identifiable cause prospectively underwent CE-MRA. >50% renal artery stenosis was considered significant. Clinical parameters (blood pressure, serum creatinine, history of hypertension/hyperlipidaemia) were compared in patients with and without RAS using an unpaired t-test. Results expressed; mean (+/-SD).

RESULTS

20 patients (4 male, 16 female, age 78.5+/-11 years) underwent CE-MRA. 9 patients (45%) had significant RAS (6 (30%) bilateral, 3 (15%) unilateral). Systolic BP was higher in patients with RAS (192+/-38 mm Hg) than those without (134+/-30 mm Hg) (p<.005). Diastolic BP was higher in patients with RAS (102+/-23 mm Hg) than those without (76+/-17 mm Hg) (p<.01). All patients with RAS and 6/11(55%) patients without RAS had a history of hypertension. No significant difference in creatinine or hyperlipidaemia history was observed.

CONCLUSION

The prevalence of RAS in patients presenting with FPE is 45%. The diagnosis should be considered in patients presenting with unexplained acute pulmonary oedema, particularly if hypertensive at presentation.

One year clinical outcomes of renal artery stenting: the results of ODORI Registry

The safety, efficacy and long term clinical benefits of renal artery revascularization by stenting are still a matter of debate. The aim of our study was to define the safety and efficacy of renal artery stenting with the Tsunami peripheral stent (Terumo Corporation, Tokyo, Japan). The ODORI was a prospective, multicentre registry which enrolled 251 consecutive patients, (276 renal arteries) in 36 centres across Europe. The primary endpoint was acute procedural success defined as <30% residual stenosis after stent placement. Secondary endpoints included major adverse events, blood pressure control, serum creatinine level, and target lesion revascularization (TLR) at 6 and 12 months. Patients were 70 +/- 10 years old, 59% were male, 33% had diabetes, and 96% hypertension. The main indications for renal stent implantation were hypertension in 83% and renal salvage in 39%. Direct stent implantation was performed in 76% of the cases. Acute success rate was 100% with residual stenosis of 2.5 +/- 5.4%. Systolic/diastolic blood pressure decreased from a mean of 171/89 at baseline to 142/78 mmHg at 6 months (p < 0.0001 vs. baseline), and 141/80 mmHg at 12 months (p < 0.0001 vs. baseline). Mean serum creatinine concentration did not change significantly in the total population. However, there was significant improvement in the highest tercile (from 283 micromol/l at baseline to 205 and 209 micromol/l at 6 and 12 months respectively). At 12-months, rates of restenosis and TLR were 6.6 and 0.8% respectively. The 12 month cumulative rate of all major clinical adverse events was 6.4% while the rate of device or procedure related events was 2.4%. In hypertensive patients with atherosclerotic renal artery stenosis Tsunami peripheral balloon-expandable stent provides a safe revascularization strategy, with a potential beneficial impact on hypertension control and renal function in the highest risk patients.

Effect of baseline glomerular filtration rate on renal function following stenting for atherosclerotic renal artery stenosis

OBJECTIVE

Percutaneous transluminal renal artery angioplasty and stenting (PTRAS) is one treatment option for atherosclerotic renal artery stenosis (ARAS). However, factors predicting the outcome remain controversial. This study investigated the effect of the baseline glomerular filtration rate (GFR) on renal function after PTRAS in patients with ARAS.

MATERIAL AND METHODS

Patients who underwent PTRAS due to significant ARAS (luminal narrowing > or = 60%) were enrolled. The patients were divided into control (n = 57; estimated GFR (eGFR) > or = 60 ml/min/1.73 m(2)) and chronic renal failure (CRF) groups (n = 53; eGFR < 60 ml/min/1.73 m(2)), according to the baseline eGFR.

RESULTS

The mean age at the time of PTRAS was 62 +/- 9 years, and the mean duration of follow-up was 50 +/- 26 months. There was a significant decrease in eGFR after PTRAS in the control group, whereas the CRF group showed no significant change in eGFR. The percentage change in eGFR was negatively correlated with the baseline eGFR (r = -0.274, p = 0.004). Multivariate linear regression revealed that only baseline eGFR predicted the change in eGFR (p = 0.032).

CONCLUSIONS

PTRAS was more effective at preserving renal function in patients with moderately impaired renal function. Thus, baseline GFR may indicate the expected renal function outcome after PTRAS.

Renal parenchymal preservation after percutaneous renal angioplasty and stenting

BACKGROUND

The intent of endovascular therapy for symptomatic atherosclerotic renal artery stenosis (ARAS) is to preserve parenchyma and avoid renal-related morbidity. The aim of this study is to examine the impact of renal artery intervention on parenchymal preservation.

METHODS

We performed a retrospective analysis of records from patients who underwent endovascular intervention for ARAS and were followed by duplex ultrasound between 1990 and 2008. Renal volume (in cm(3)) was estimated in all patients as renal length (cm) x renal width (cm) x renal depth (cm) x 0.5. The normal renal volume was calculated as 2 x body weight (kg) in cm(3). Failure of preservation was considered to be a persistent 10% decrease in volume. Clinical benefit defined as freedom from renal-related morbidity (increase in persistent creatinine >20% of baseline, progression to hemodialysis, death from renal-related causes) was calculated.

RESULTS

Five hundred ninety-two renal artery interventions were performed. One hundred eighty-six kidneys suffered parenchymal loss (>5%) with an actuarial parenchymal loss rate of 29% +/- 1% at five years respectively. There were no significant differences in age, gender, starting renal volume, or kidney size. However, patients with parenchymal loss had lower eGFR (45 +/- 24 vs 53 +/- 24 mL/min/1.73 m(2); Loss vs noLoss, P = .0002, Mean +/- SD) higher resistive index (0.75 +/- 0.9 vs 0.73 +/- 0.10; P = .0001) and worse nephrosclerosis grade (1.43 +/- 0.55 vs 1.30 +/- 0.49; P = .006) then those not suffering parenchymal loss. Parenchymal loss was associated with significantly worse five-year survival (26% +/- 4% vs 48% +/- 2%; Loss vs noLoss; P < .001) and freedom from renal-related morbidity (70% +/- 5% vs 82% +/- 2%; P < .05) with increased numbers progressing to dialysis (17% vs 7%; P < .006).

CONCLUSION

While parenchymal preservation occurs in most patients, parenchymal loss occurs in 31% of patients and is associated with markers of impaired parenchymal perfusion (resistive index and nephrosclerosis grade) at the time of intervention. Pre-existing renal size or volumes were not predictive of parenchymal loss. Parenchymal loss is associated with a significant decrease in survival and a marked increased renal related morbidity and progression to hemodialysis.

Limitations of angiography for the assessment of renal artery stenosis and treatment implications

Renovascular hypertension due to atherosclerotic renal artery stenosis is the most common cause of secondary hypertension. Percutaneous catheter-based renal artery revascularization has been increasingly utilized for the treatment of renal artery stenosis. Renal artery stenting has a high technical success rate, but the rate of improvement in hypertension is somewhat less than expected with this technique. Misinterpretation of angiographic images may play a role in these unfavorable clinical results. We present a case in which the diagnosis of severe renal artery stenosis was not apparent by angiography. Intravascular ultrasound and translesional pressure gradient measurements during arteriography can help to determine the precise severity of stenosis and may augment the clinical results of percutaneous renal artery stent placement.