Sirolimus-Eluting versus Bare-Metal Low-Profile Stent for Renal Artery Treatment (GREAT Trial): Angiographic Follow-up after 6 Months and Clinical Outcome up to 2 Years

Interventions for renal artery stenosis: Appraisal of novel physiological insights and procedural techniques to improve clinical outcome

Randomized clinical trials failed to show additional benefit of renal artery stenting on top of medical therapy. Instead of writing an obituary on renal artery stenting, we try to explain these disappointing results. A transstenotic pressure gradient is needed to reduce renal perfusion and to activate the renin-angiotensin-aldosterone system. In only a minority of patients included in trials, a transstenotic pressure gradient is measured and reported. Like the coronary circulation, integration of physiological lesion assessment will allow to avoid stenting of non-significant lesions and select those patients that are most likely to benefit from renal artery stenting. Renal artery interventions are associated with peri-procedural complications. Contemporary techniques, including radial artery access, no-touch technique to engage the renal ostium and the use of embolic protection devices, will minimize procedural risk. Combining optimal patient selection and meticulous technique might lead to a netto clinical benefit when renal artery stenting is added to optimal medical therapy.

Therapy for Renal Artery Stenosis: A Call for Change

CLINICAL IMPACT

We present a brief case description of a patient who benefitted from stenting in ARAS and provide a comprehensive review of ARAS; its prevalence, pathophysiology, clinical manifestations, diagnosis and treatment. We review the evidence for and against stenting in ARAS as well as consensus guidelines for stenting. Our review is valuable as we argue that stenting in ARAS is underutilized and the randomized control data for stenting in those patients who may benefit most is lacking. Our review will provide an important perspective for clinicians faced with decisions of how to treat ARAS.

Double kiss mini-crush technique to treat complex recurrent renal artery in-stent restenosis

The double-kiss mini-crush (DKMC) technique has been successfully deployed in the past for the treatment of complex coronary lesions even for left main lesions. Our case report consists of a proof-of-principle that the DKMC technique can be successfully translated as well to the field of complex renal artery lesions. Insightful thinking out-of-the "coronary" box in concert with skillful off-label application of coronary stenting procedures may open the gate for unprecedented opportunities for the treatment of difficult-to-tackle in-stent restenosis in the renal circulation.

Simultaneous Kissing Balloon Stenting Technique in Management of Two Branches of Right Renal Artery Bifurcation: A Case Report

Atherosclerosis and fibromuscular dysplasia are the commonest types of diseases associated with renovascular hypertension, with atherosclerosis accounting for 70%-80% of all cases and the latter accounting for 10% of cases. We report a case of a 65-year-old asian male with stenosis of the right renal artery with early bifurcation treated by percutaneous balloon dilation and simultaneous kissing balloon stenting technique.

Endovascular interventions in main renal artery pathologies: an overview and update

Renal arteries are involved in a wide spectrum of pathologies including atherosclerosis, fibromuscular dysplasia, Takayasu arteritis, aneurysms, and aortic type B dissections extending into main renal arteries. They manifest as renovascular hypertension, renal ischemia, and cardiovascular dysfunction. The location of the renal arteries in relation to the abdominal aortic aneurysm is a critical determinant of interventional options and long-term prognosis. This article provides a comprehensive review of the role of interventional radiologists in transcatheter interventions in various pathologies involving the main renal arteries with analysis of epidemiology, pathophysiology, newer interventional techniques, and management options.

Factors predicting long-term outcomes of percutaneous angioplasty and stenting of the superior mesenteric artery for chronic mesenteric ischemia

Background: To analyse the long-term outcomes of percutaneous angioplasty and stenting of the superior mesenteric artery (SMA) in the treatment of chronic mesenteric ischemia (CMI), and to assess predictive factors for a better clinical outcome. Patients and methods: Retrospective analysis of 76 consecutive patients, treated percutaneously for CMI between January 1999 and January 2018 and followed up until the end of 2018. Patients' pre-, peri- and post-interventional clinical and radiological data were gathered from the institutional electronic medical records. The Kaplan Meier method with log rank test or the Cox model were used to analyse overall survival; the cumulative incidence function with Pepe and Mori test or the Fine and Grey model were used to analyse relapse-free survival, considering death as a competing event. Results: Seventy-six consecutive patients with a mean age of 72 years were included in the study. Catheter-angiography revealed an ostial or non-ostial >90% stenosis in n=23 (29.7%) and n=53 (69.7%) of included patients, respectively. Immediate clinical success was achieved in n=68 (89.5%), and procedural complications were observed in n=13 (17.1%) patients. Long-term follow-up revealed relapse of symptoms in n=21 (28.8%) patients, and overall survival estimates are 81.8%, 57.0% and 28.2% after two, five and ten years of follow-up, respectively. A trend towards longer relapse-free survival was found in the circumferential stenosis group (78.2% at five years) compared with the non-circumferential stenosis group (55.5%) (P=0.063). Conclusions: Angioplasty and stenting of the SMA for CMI is relatively safe and effective despite a substantial number of patients experiencing clinical relapse over time. Patients with focal, circumferential stenosis might have longer relapse-free survival than patients with non-circumferential stenosis.

Renal and Mesenteric Artery Intervention

Atherosclerotic renal artery stenosis is the most common cause of secondary hypertension and may cause progressive renal disease and cardiac destabilization syndromes. Guideline-directed medical therapy is advised in all patients. Patients with refractory symptoms and hemodynamically significant stenoses are more likely to benefit from renal artery stent placement. Chronic mesenteric ischemia (CMI) is an infrequent and difficult to diagnose illness. Due to robust collateralization, clinical symptoms from mesenteric artery stenosis or occlusion is uncommon. Atherosclerosis is the most common etiology of CMI. Current evidence suggests that, compared with open surgical repair, endovascular therapy is the most cost-effective choice for CMI.

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: When to Revascularize in 2017

Atherosclerotic renal artery stenosis is the leading cause of secondary hypertension; it can also cause progressive renal insufficiency and cardiovascular complications such as refractory heart failure and flash pulmonary edema. Medical therapy including risk factor modification, renin-angiotensin-aldosterone system antagonists, lipid lowering agents, and antiplatelet therapy is the first line of treatment in all patients. Patients with uncontrolled renovascular hypertension despite optimal medical therapy, ischemic nephropathy, and cardiac destabilization syndromes who have severe renal artery stenosis are likely to benefit from renal artery revascularization. Screening for renal artery stenosis can be done with Doppler ultrasonography, computed tomographic angiography and magnetic resonance angiography. Invasive physiologic measurements are useful to confirm the severity of renal hypoperfusion and therefore improve the selection patients likely to respond to renal artery revascularization. Primary patency exceeds 80% at 5 years and surveillance for in-stent restenosis can be done with periodic clinical, laboratory, and imaging follow-up.

Treatment of In-Stent Restenosis in Patients with Renal Artery Stenosis

PURPOSE

To determine clinical outcomes of patients treated for renal artery in-stent restenosis (ISR) with atherosclerotic renal artery stenosis.

MATERIALS AND METHODS

A retrospective review was performed of the clinical data of all patients who underwent renal artery stent placement for atherosclerotic renal artery stenosis from 1996 to 2009. Medical records of patients were reviewed for relevant clinical history, including blood pressure, antihypertensive medications, and renal function data before and after an intervention. In 1,052 patients, 1,090 renal artery stent placements were performed. Of these, 101 stents in 79 patients developed ISR, which was treated with either percutaneous transluminal angioplasty (PTA) or repeat stent placement. Procedural details, including modality of intervention, stent diameter, and time to restenosis, were recorded. Hypertensive agent and use of statins were recorded. Univariate analysis was performed to identify risk factors associated with restenosis after treatment of ISR.

RESULTS

Patients treated with repeat stent placement were 6.89 times more likely to lose patency after treatment than patients treated with PTA (P < .01). No additional clinical or procedural factor, including smoking history; presence of cardiac, renal, or metabolic disease; use of statin at time of ISR treatment; or diameter of treatment (stent or PTA), had a significant association with duration of stent or angioplasty patency.

CONCLUSIONS

Treatment of renal artery ISR with PTA among patients with atherosclerotic renal artery stenosis has a lower rate of subsequent ISR compared with repeat stent placement.

Renal Transplant Arterial Stenosis Treated With Bare-Metal Versus Drug-Eluting Stents: Comparison of Treatment Outcomes

INTRODUCTION

This study aims to evaluate outcomes of bare-metal stents (BMS) versus drug-eluting stents (DES) in patients who undergo stenting for transplant renal arterial stenosis.

MATERIALS AND METHODS

We retrospectively reviewed records of renal transplantation patients who underwent transplant renal arterial stenting from September 2009 to September 2013. All stents greater than 5 mm were excluded to allow for equivalent comparison between the DES and BMS groups. Statistical comparisons were performed using a two-tailed Fischer exact test, and analysis of continuous variables was analyzed using a one-way analysis of variance.

RESULTS

The final study population included a total of 18 patients who received either BMS or DES (11 and 7 patients, respectively) for transplant renal arterial stenosis. The most common indications for stenting were increasing creatinine level and abnormal Doppler velocities. There were more re-interventions with BMS (n = 4/11) than DES (n = 0/7), but the trend was not statistically significant (P = .12). Three patients who received BMS had a clinically significant decrease in blood pressure versus 4 in the DES group (P = .33). Six patients who received BMS had a clinically significant decrease in creatinine level versus 3 in the DES group (P = 1.0).

CONCLUSION

There is an absolute but not statistically significant difference in the incidence of restenosis requiring repeat intervention between the BMS and DES groups. No difference was detected in clinical success as measured by decreases in blood pressure or creatinine. Future larger studies are needed to corroborate these findings.

Renal Artery Stent Outcomes: Effect of Baseline Blood Pressure, Stenosis Severity, and Translesion Pressure Gradient

BACKGROUND

Multiple randomized clinical trials comparing renal artery stent placement plus medical therapy with medical therapy alone have not shown any benefit of stent placement. However, debate continues whether patients with extreme pressure gradients, stenosis severity, or baseline blood pressure benefit from stent revascularization.

OBJECTIVES

The study sought to test the hypothesis that pressure gradients, stenosis severity, and/or baseline blood pressure affects outcomes after renal artery stent placement.

METHODS

Using data from 947 patients with a history of hypertension or chronic kidney disease from the largest randomized trial of renal artery stent placement, the CORAL (Cardiovascular Outcomes in Renal Atherosclerotic Lesions) study, we performed exploratory analyses to determine if subsets of patients experienced better outcomes after stent placement than the overall cohort. We examined baseline stenosis severity, systolic blood pressure, and translesion pressure gradient (peak systolic and mean) and performed interaction tests and Cox proportional hazards analyses for the occurrence of the primary endpoint through all follow-up, to examine the effect of these variables on outcomes by treatment group.

RESULTS

There were no statistically significant differences in outcomes based on the examined variables nor were there any consistent nonsignificant trends.

CONCLUSIONS

Based on data from the CORAL randomized trial, there is no evidence of a significant treatment effect of the renal artery stent procedure compared with medical therapy alone based on stenosis severity, level of systolic blood pressure elevation, or according to the magnitude of the trans-stenotic pressure gradient. (Benefits of Medical Therapy Plus Stenting for Renal Atherosclerotic Lesions [CORAL]; NCT00081731).

Endovascular versus medical therapy for atherosclerotic renovascular disease

The diagnosis of renal artery stenosis (RAS) has become increasingly common in part due to greater awareness of ischemic renal disease and increased use of diagnostic techniques. Over 90 % of RAS cases are caused by atherosclerotic renovascular disease (ARVD). Patients with ARVD are at high risk for fatal and nonfatal cardiovascular and renal events. The mortality rate in patients with ARVD is high, especially with other cardiovascular or renal comorbidities. Recent clinical studies have provided substantial evidence concerning medical therapy and endovascular interventional therapeutic approaches for ARVD. Despite previous randomized clinical trials, the optimal therapy for ARVD remained uncertain until the results of the Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial were released recently. CORAL demonstrated that optimal medical therapy was equally effective to endovascular therapy in the treatment of ARVD. Clinicians can now practice with more evidence-based medicine to treat ARVD and potentially decrease mortality in patients with ARVD using optimal medical therapy.

Fracture of a sirolimus-eluting stent in renal artery stenosis

Atherosclerosis accounts for most adult cases of renal artery stenoses (RAS). Revascularization of atherosclerotic RAS is beneficial in terms of improved blood pressure control, preservation of renal function and overall decrease of cardiovascular risk, in particular in mononephric patients. Endovascular stenting has been proven superior to percutaneous transluminal angioplasty (PTA) alone in terms of initial success and restenosis rates in atherosclerotic RAS. In this case report revascularization of atherosclerotic RAS in a mononephric patient is presented and the long-term follow-up and complications of PTA and stenting are illustrated. Our case is the first report of fracture of a sirolimus-eluting stent overlapped to a previously implanted Palmaz-Schatz in the left renal artery. The mechanisms and possible remedies of this complication are discussed.

Restoration of renal allograft function via reduced-contrast percutaneous revascularization of transplant renal artery stenosis

Transplant renal artery stenosis (TRAS), the most common vascular complication of kidney transplantation, can lead to heart failure, uncontrolled hypertension, and irreversible dysfunction of the transplanted kidney. Percutaneous revascularization can improve outcomes in well-selected patients with symptomatic TRAS, but the intervention itself poses risk to the transplanted kidney because of the quantities of nephrotoxic contrast solution that often are used. We report the case of a patient with TRAS who, 5 months after undergoing a kidney transplant, developed allograft dysfunction and heart failure that required hemodialysis. We performed angioplasty and stenting of the TRAS, using intravascular ultrasonography and fluoroscopy as our primary imaging methods. To minimize further damage to a potentially viable kidney, the volume of intravascular contrast medium used was trivial (a total of 9 cc). Revascularization of the patient's TRAS restored his renal function: within 4 weeks of the procedure, he no longer needed hemodialysis, and his heart failure symptoms had resolved. This case emphasizes the value of early definitive treatment of TRAS and the usefulness of intravascular ultrasonography to minimize the amount of contrast medium used in endovascular procedures.

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.

Current views on the management of atherosclerotic renovascular disease

Atherosclerotic renovascular disease (ARVD) is a common condition in both elderly patients and those with other vascular disease. No published randomized controlled trial has demonstrated an overall benefit of revascularization on any clinical or biochemical end-point, and optimal medical therapy in this condition is not clearly defined. In this review we consider the epidemiology of ARVD and discuss the evidence for current medical treatment. We also address the literature on revascularization, consider settings in which an interventional approach may still be considered, and touch upon on-going areas of research.

Renal intervention to treat hypertension

Renal artery intervention to treat hypertension is one of the frontiers of ongoing research in combating this epidemic. This article focuses on recent data regarding PTRS and catheter-based renal sympathetic denervation. Despite progress in this field large multicenter, randomized trials that compare these treatment modalities with medical therapy for hypertension are lacking.

Use of drug-eluting stent with provisional T-stenting technique in the treatment of renal artery bifurcation stenosis; long-term angiographic follow-up

Atherosclerotic renal artery stenosis (RAS) usually involves the ostium and the proximal one-third of the renal artery main branch. Percutaneous renal artery angioplasty with stent placement is a well recognized treatment for atherosclerotic RAS. Occasionally, atherosclerotic RAS involves renal artery bifurcations. However, stent implantation in atherosclerotic RAS involving bifurcation is not only troublesome, but also challenging because of side branch occlusion and in-stent restenosis (ISR). In the present report, we describe the use of drug-eluting stents (DES) with provisional T-stenting technique for the treatment of renal artery bifurcation lesion. Follow-up angiogram showed no significant ISR 18 months after the procedure. In the treatment of renal bifurcation lesions, a two-stent strategy using DES could be a viable option in selected patients.

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.

Two-stent strategy for renal artery stenosis with bifurcation lesion

Renal artery stenosis (RAS) with a bifurcation lesion is a challenge for interventional therapy. The aim of this study is to summarize our experience in RAS with a bifurcation lesion. Five patients with RAS involving bifurcation lesion are described. In cases 1 to 3, a single-stent strategy was first adopted. However, these three patients were converted to a two-stent strategy for bailout stent implantation in the side branches. In cases 4 and 5, a simultaneous kissing stent technique was performed. Angiography showed that the reference vascular diameter of the main branch was much larger than those of the side branches. Although obvious residual stenosis existed in cases 1 to 3 after stent implantation, no obvious residual stenosis was seen in cases 4 and 5. Renal artery duplex sonography was performed in cases 1 through 5 at 6, 7, 7, 8, and 6 months, respectively, after the procedures. No evidence of restenosis or occlusion was seen. In conclusion, stent implantation with the simultaneous kissing stent technique may result in more simple and more satisfactory immediate angiographic results.

Primary stenting for atherosclerotic renal artery stenosis

INTRODUCTION

Endovascular treatment for atherosclerotic renal artery stenosis (ARAS) was first performed >30 years ago and its use has increased rapidly since then. However, only recently have large randomized trials rigorously evaluated its clinical benefit.

METHODS

We systematically reviewed the controlled studies on primary stenting for atherosclerotic renal artery stenosis. Studies were included if they compared the outcome of stenting with other treatments, or the outcome associated with different stent characteristics or stenting methods.

RESULTS

Stenting is preferred over angioplasty alone and over surgery when revascularization is indicated for ostial ARAS, except in cases of coexistent aortic disease indicating surgery. Randomized controlled trials showed no significant benefit and substantial risk of renal artery stenting over medication alone in patients with atherosclerotic ARAS without a compelling indication. Improvements in the procedure, such as with distal embolic protection devices and coated stents, are not associated with better clinical outcomes after stent placement for ARAS.

CONCLUSION

Recent evidence shows that impaired renal function associated with ARAS is more stable over time than previously observed. Optimal medical treatment should be the preferred option for most patients with ARAS. Only low-level evidence supports compelling indications for revascularization in ARAS, including rapidly progressive hypertension or renal failure and flash pulmonary edema.

Targeting stents with local delivery of paclitaxel-loaded magnetic nanoparticles using uniform fields

The use of stents for vascular disease has resulted in a paradigm shift with significant improvement in therapeutic outcomes. Polymer-coated drug-eluting stents (DES) have also significantly reduced the incidence of reobstruction post stenting, a disorder termed in-stent restenosis. However, the current DESs lack the capacity for adjustment of the drug dose and release kinetics to the disease status of the treated vessel. We hypothesized that these limitations can be addressed by a strategy combining magnetic targeting via a uniform field-induced magnetization effect and a biocompatible magnetic nanoparticle (MNP) formulation designed for efficient entrapment and delivery of paclitaxel (PTX). Magnetic treatment of cultured arterial smooth muscle cells with PTX-loaded MNPs caused significant cell growth inhibition, which was not observed under nonmagnetic conditions. In agreement with the results of mathematical modeling, significantly higher localization rates of locally delivered MNPs to stented arteries were achieved with uniform-field-controlled targeting compared to nonmagnetic controls in the rat carotid stenting model. The arterial tissue levels of stent-targeted MNPs remained 4- to 10-fold higher in magnetically treated animals vs. control over 5 days post delivery. The enhanced retention of MNPs at target sites due to the uniform field-induced magnetization effect resulted in a significant inhibition of in-stent restenosis with a relatively low dose of MNP-encapsulated PTX (7.5 microg PTX/stent). Thus, this study demonstrates the feasibility of site-specific drug delivery to implanted magnetizable stents by uniform field-controlled targeting of MNPs with efficacy for in-stent restenosis.

The current state of endovascular therapy in the evaluation and management of renovascular disease

Hypertension is the most common reason for physician office visits among nonpregnant adults in the United States; up to one-third of Americans over the age of 18 have been diagnosed with hypertension. Patients with physiologically significant renal artery stenosis often go unnoticed because hypertension can often be well controlled with antihypertensive medications. As a result, screening for renovascular causes of hypertension is rarely done. However, the likelihood of renovascular disease increases in patients with acute, severe, or refractory hypertension and should be explored in patients who fall into these categories. Renovascular disease is a crucial consideration in the management of hypertension due to its increasing incidence and its potential for reversibility. Although renovascular disease accounts for less than 1% of patients with mild hypertension, it is estimated that between 10 and 45% of white patients with severe or malignant hypertension have renal artery stenosis (RAS). In this population, diagnosing and treating RAS can have a profound and long-lasting effect on the treatment of hypertension.

Sirolimus-eluting stent placement for refractory renal artery in-stent restenosis: sustained patency and clinical benefit at 24 months

Abstract

Renal artery stenosis may cause or exacerbate hypertension and renal failure. Percutaneous transluminal renal artery stent placement, increasingly the first-line therapy for ostial atherosclerotic renal artery stenosis, can be complicated by in-stent restenosis weeks to months after the procedure. There is currently no consensus for the treatment of in-stent restenosis. Sirolimus-eluting stents have been shown to be effective to treat in-stent restenosis in the coronary circulation. We report a case of sustained 24-month patency after repair of recurrent renal artery in-stent restenosis with use of a sirolimus-eluting stent.

Treatment of renal artery in-stent restenosis with sirolimus-eluting stents

The objective of this study was to analyze the use of sirolimus-eluting stent (SES) placement for the treatment of renal artery in-stent restenosis (RA-ISR). The optimal treatment of RA-ISR has not been fully elucidated to date. We retrospectively analyzed consecutive patients from our institution who underwent treatment of RA-ISR with a SES from May 2004 to June 2006. Using duplex ultrasound, RA-ISR (> 60% diameter) was determined by peak systolic velocity (PSV) > 300 cm/s and renal aortic ratio (RAR) > 4.0. Renal function (creatinine) and blood pressure were measured at baseline and follow-up. SESs were implanted in 16 patients (22 renal arteries) during the study period. The study cohort was predominantly female (75%) with a mean age of 68 +/- 12 years. RA-ISR was treated with SESs with a mean diameter of 3.5 mm and mean length of 17.9 +/- 3.8 mm. The mean post-dilation balloon diameter was 4.8 +/- 0.6. The baseline renal artery PSV was 445 +/- 131 cm/s with a mean RAR of 5.0 +/- 1.6. Follow-up information was available in 21 renal arteries. During a median follow-up of 12 months (range: 9-15 months), 15 renal arteries (71.4%) developed recurrence of ISR by ultrasonographic criteria. Univariate analysis revealed that female sex was an independent predictor of recurrence of ISR after SES implantation (p < 0.05). In conclusion, placement of a SES for the treatment of ISR in renal arteries is associated with high initial technical success but significant restenosis on duplex ultrasonography at follow-up.

Atherosclerotic renal artery stenosis: current therapy and future developments

Atherosclerotic renal artery stenosis affects between 2 and 4 million people in the United States alone and likely has a higher prevalence than previously thought. Renal artery stenosis has been increasingly recognized in recent years, especially in patients with cardiovascular disease. It has been associated with hypertension, renal dysfunction, and sudden onset of pulmonary edema. Patients with symptomatic and hemodynamically significant renal artery stenosis are candidates for revascularization. Revascularization is most often accomplished by renal artery stenting, which has high success rates in terms of patency and low complication rates. An important element in managing patients with renal artery stenosis is selecting those patients who are most likely going to benefit from revascularization. This review article focuses on the clinical diagnosis, current treatment options, and future directions regarding treatment of patients with renal artery stenosis.

[Renal artery stenosis. Pathophysiology--diagnosis--therapy]

Renal artery stenosis (RAS) is both a common and progressive disease and its prevalence in patients > 65 years is 6.8%. In patients with known or suspected atherosclerosis undergoing coronary angiography, a frequency of even 11-23% is reported in the literature. Despite this high prevalence, there is an ongoing discussion about the indications for revascularization and it is currently unclear, whether renal artery revascularization reduces adverse cardiovascular and renal events. Nevertheless, the number of interventions for RAS is rising steadily, although up to 40% of patients do not profit from this intervention. This fact underlines the necessity of a thorough diagnostic work-up before intervention, integrating morphological and functional tests. For morphological evaluation, multislice computed tomography, magnetic resonance tomography or digital subtraction angiography can be done. In experienced centers, Doppler ultrasound can serve as an excellent functional tool, to assess the physiological relevance of an RAS, but also invasive measurements of pressure and flow provide valuable information about the significance of stenoses; however, these methods will have to be assessed with respect to their value to predict long-term outcome. Although percutaneous intervention of RAS is associated with a substantially lower risk of major adverse events as compared to surgery, by using contrast media this procedure holds the risk of deterioration of renal function and of a small number of procedure-dependent complications as well. Thus, a careful consideration of pros and cons of this procedure is mandatory.

[Hypertension in patients with renal artery stenosis]

Renal artery stenosis (RAS) is often present in patients with severe hypertension and atherosclerotic vascular disease. In this setting it is important to screen patients for renovascular disease, e.g. with Duplex-ultrasound, CT- or MR-angiography. The challenge of treating these patients is to find the evidence proving that the RAS is responsible for hypertension and/or renal dysfunction. Measurement of the intra-arterial pressure gradient is necessary in order to determine hemodynamic relevance. On the other side, in these patients hypertension is often of primary and/or renoparenchymatous origin and is aggravated by a renovascular disease. This explains why hypertension cannot be cured even if a high grade stenosis has been removed. In addition, thromb- and cholesterol-embolic material is often mobilized during an invasive procedure and leads to renaparenchymatous ischemia which sustains hypertension after intervention. An individual evaluation of profit versus risk is important for the decision for or against an invasive procedure, especially since there is no sufficient evidence for a decrease of mortality after interventions of RAS. The optimal conservative treatment, including the treatment of atherosclerotic risk factors is recommended.

Drug-eluting stents in the management of peripheral arterial disease

Since major meta-analyses of randomized controlled trials in interventional cardiology showed the potential of drug-eluting stents in decreasing restenosis and reintervention rates after coronary artery stenting, one of the next steps in the treatment of arterial occlusive disease is the transfer of the active coating technology towards peripheral arterial interventions. In this manuscript, we aim to provide a literature overview on available peripheral (lower limb, renal, and supra-aortic) drug-eluting stent applications, debate the cost implications, and give recommendations for future treatment strategies.