A review of the current treatment of renal artery stenosis.

PURPOSE: Atherosclerotic renal artery stenosis (ARAS) is associated with morbidity and mortality consequent to progressive ischemic renal failure and the cardiovascular consequences of hypertension. There is considerable uncertainty concerning the optimal management of patients with this condition. This review considers the aetiological factors and the physiologic consequences of ARAS and compares the results of clinical studies of medical and endovascular therapies on blood pressure control and preservation of renal function. RESULTS: Although, in patients with fibromuscular disease the results of percutaneous transluminal angioplasty (PTA) are clearly superior to medical therapy and surgery, in asymptomatic patients with ARAS the antihypertensive benefits and preservation of renal function of endovascular, surgical and medical therapies appear similar. In selected symptomatic patients interventions may, however, be life-saving. Surgery is generally reserved for arterial occlusions with preserved renal parenchyma and function. CONCLUSIONS: The results of larger, multicentre, randomised, controlled trials are required to clearly clarify the role of interventional therapy in asymptomatic patients.     

Renal Artery Stenosis: To Intervene,or Not to Intervene, “That is the Question”

Renal artery stenosis (RAS) due to atherosclerosis continues to be a major cause of secondary hypertension. It can also lead to renal dysfunction due to ischemic nephropathy. While major clinical trials have emphasized that medical management should be preferred over angioplasty and stenting for the treatment of renal artery stenosis, clinical scenarios continue to raise doubts about the optimal management strategy. Herein, we present two cases that were admitted with hypertensive emergency and renal function deterioration. Medical therapy failed to control the blood pressure and in one patient, renal failure progressed to a point where renal replacement therapy was required. Both patients underwent angioplasty (for >90% stenosis) and stent insertion with successful resolution of stenosis by interventional radiology. Postoperatively, blood pressure gradually decreased with improvement in serum creatinine. Dialysis therapy was discontinued. At 4‐ and 8‐month follow‐up, both patients continue to do well with blood pressure readings in the 132–145/70–90 mmHg range. This article highlights the importance of percutaneous interventions in the management of atherosclerotic RAS and calls for heightened awareness and careful identification of candidates who would benefit from angioplasty and stent insertion.     

Renovascular hypertension: current concepts

Hypertension produced by renal artery occlusive disease is an important secondary form of hypertension. Clinicians commonly encounter forms of renal arterial disease of varying severity, many of which are of little hemodynamic significance when first detected. Experimental studies emphasize that transient activation of the renin-angiotensin-aldosterone system is necessary for initiation of renovascular hypertension. At some point, angiotensin II activates additional mechanisms responsible for sustained increased blood pressure including sodium retention, endothelial dysfunction, and vasoconstriction related to production of reactive oxygen species. Widespread application of agents that block the renin-angiotensin system, including angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers, render many patients with unilateral renal arterial disease manageable primarily by medical means for many years. In the setting of high a priori likelihood of renovascular disease, recognizing the potential for disease progression during medical therapy and individually evaluating the risks and benefits of renal revascularization are important tasks. Recent prospective studies show limited, but real, benefit regarding blood pressure control for patients with atherosclerotic disease. Whether earlier renal revascularization offers benefits regarding improved morbidity and mortality from cardiovascular end point reduction is an important question to be addressed in multicenter, prospective, randomized trials. Our paradigm stresses the fact that patients with renovascular hypertension require intensive blood pressure control and cardiovascular risk factor intervention, both before and after revascularization. Hence, management of such patients requires close attention and periodic review regarding restenosis and progression of vascular disease.     

Revascularization for atherosclerotic renal artery stenosis: the treatment of choice?

Atherosclerotic renal artery stenosis (ARAS) is an important cause of renal dysfunction and secondary hypertension, and is associated with adverse cardiovascular events and increased mortality. The natural history of ARAS is characterized by anatomic disease progression and/or renal dysfunction in only a minority of patients. Medical therapy for ARAS is directed primarily toward blood pressure control and cardiovascular risk factor reduction. Renal artery revascularization is an additional treatment option for ARAS associated with ischemic nephropathy or severe, poorly controlled hypertension despite aggressive medical therapy. Unfortunately, the benefits associated with revascularization versus medical therapy alone remain unproven. Renal artery revascularization may be accomplished through open surgical revascularization or angioplasty and stenting. Although surgical renal revascularization is associated with more durable results and relatively lower risk for postoperative renal function decline, the increased risk of death or major complications associated with this management approach limit its use in patients with significant comorbidities. Renal artery angioplasty and stenting is being utilized with increasing frequency but is of uncertain benefit and is associated with rates of post-intervention renal function improvement and deterioration that are approximately equal. Renal function outcomes associated with angioplasty and stenting may be improved through a selective treatment approach and utilization of distal embolic protection. Renal artery revascularization represents the only treatment alternative for patients unresponsive to medical management, and is therefore the 'treatment of choice' in this select group. Results of ongoing randomized trials are eagerly anticipated and may provide useful guidance for future management of ARAS.     

Safety and efficacy of transjugular renal biopsy performed by interventional nephrologists

Obtaining renal tissue is often critical in the diagnosis and management of patients with renal disease of unknown etiology. Bleeding diathesis, liver disease, and obesity are common contraindications for percutaneous renal biopsy. In high-risk patients, transjugular renal biopsy is believed to be a safe and effective procedure. This study reports the experience of an academic interventional nephrology program with performing transjugular renal biopsy. We performed a retrospective observational study of 23 patients with either acute or chronic kidney disease with contraindications for percutaneous renal biopsy. All transjugular renal biopsies were performed by interventional nephrologists at our university. We studied the efficacy and safety of transjugular renal biopsy in these patients. Twenty out of 23 (87%) of the procedures yielded adequate tissue for pathologic diagnosis. Three (13%) patients required blood transfusions, none required coil embolization or nephrectomy, and there were no deaths. Even though performing transjugular renal biopsy requires considerable technical expertise and must be performed in an interventional radiology suite, it can be safely and effectively performed by well-trained interventional nephrologists to achieve pathological diagnosis.     

同种异体肾移植术后移植肾动脉狭窄 介入治疗的临床疗效分析

目的探讨同种异体肾移植术后移植肾动脉狭窄（TRAS）介入治疗的临床疗效。方法介入治疗同种异体肾移植术后TRAS患者22例,其中单纯球囊扩张治疗10例（球囊组）,内支架治疗12例（支架组）。对所有患者术前及术后2年内血压、肾功能以及生活质量进行评估,并与同期接受单纯药物治疗的6例TRAS患者（药物组）进行比较。结果球囊组技术成功率90.00%,支架组技术成功率100%。术后在血压及肾功能改善方面,球囊组和支架组均取得显著疗效,两组近期疗效未见明显差异,药物组疗效不满意。术后随访6个月～2年,支架组再狭窄率16.67%,除1例不明原因治疗无效外,其余11例均能比较健康的生活和工作。球囊组手术失败1例,再狭窄率达40.00%。结论内支架植入术可作为TRAS特别是I型及Ⅱ型狭窄的首选治疗方法。     

Evidence-based medicine in renal artery stenting

Atherosclerotic renovascular disease is an increasingly recognized cause of severe hypertension and declining kidney function. Patients with atherosclerotic renovascular disease have been demonstrated to have an increased risk of adverse cardiovascular events. Over the course of the last two decades renal artery revascularization for treatment of atherosclerotic renal artery stenosis (RAS) has gained great increase via percutaneous techniques. However the efficacy of contemporary revascularization therapies in the treatment of renal artery stenosis is unproven and controversial. The indication for renal artery stenting is widely questioned due to a not yet proven benefit of renal revascularization compared to best medical therapy. Many authors question the efficacy of percutaneous renal revascularization on clinical outcome parameters, such as preservation of renal function and blood pressure control. None of the so far published randomized controlled trials could prove a beneficial outcome of RAS revascularization compared with medical management. Currently accepted indications for revascularization are significant RAS with progressive or acute deterioration of renal function and/or severe uncontrollable hypertension, renal function decline with the use of agents blocking the renin-angiotensin system and recurrent flash pulmonary edema. The key point for success is the correct selection of the patient. This article summarizes the background and the limitations of the so far published and still ongoing controlled trials.     

Advances in the medical management of renovascular hypertension

Although clinical reports have suggested that antihypertensive therapy can control blood pressure in patients with renovascular hypertension, adequate randomized studies comparing medical versus surgical management are lacking. It is well recognized that progressive deterioration in renal function can occur despite good blood pressure control. Recent experience suggests that higher-risk patients with atherosclerotic renovascular hypertension can benefit from an aggressive surgical approach, whereas newer medical therapies capable of specific inhibition of the renin-angiotensin system suggest greater potential benefits to other patients. Properly performed randomized trials comparing medical versus surgical therapy of renovascular hypertension are needed.     

Leitlinie zur chirurgischen Therapie bei Erkrankungen der Nierenarterien

Background

These guidelines are the current publication of the German guidelines for surgical revascularization of renal artery disease, focusing on atherosclerotic renal artery stenosis. These guidelines update a previous version: Allenberg JR (1998) Guidelines for renovascular disease. In: German College of Vascular Surgery (DGG) Guidelines for diagnostic and therapy in vascular surgery. Deutscher Ärzteverlag, Köln

Purpose

The aim was to evaluate the effect of surgical revascularization on clinical outcomes in adults with atherosclerotic renal artery stenosis in comparison to endovascular therapy or best medical treatment.

Data Sources

The appropriate criteria were reviewed by a literature search (MEDLINE database) and updated in order to evaluate the results of previous studies and obtain new and highly significant scientific evidence on the surgical therapy of renovascular diseases.

Data interpretation

Using the evidence-based criteria there were only two randomized trials with an evidence level type Ib, one comparing surgical revascularization with best medical treatment and another comparing surgical revascularization with percutaneous transluminal angioplasty (PTA). In both studies there were no significant differences in the outcome. However, the statistical power of these trials with a total of 110 randomized patients was poor. Many trials with evidence level II and III have been carried out. Available evidence is not sufficient to predict which intervention would result in better outcomes. There have been no randomized prospective trials comparing the three therapeutic options, surgical revascularization, PTA/stent and best medical treatment.

Conclusion

An advantage for a specific type of therapy has not yet been demonstrated. The decision for any kind of treatment approach depends on the individual renal artery lesion, the therapeutic options, skills and the necessary interdisciplinary infrastructure of the treating medical unit.     

Expert consensus: Renal denervation for the treatment of hypertension

Catheter-based renal denervation is a new method able to disrupt renal sympathetic nerves located in the adventitia of renal arteries. A randomized clinical trial showed a decrease in blood pressure in resistant hypertensive patients. In order to guide clinicians and interventional practitioner for the use of this new approach, different French scientific societies (Hypertension, Cardiology and Radiology) decided to combine their expertise and propose an expert consensus to assess benefit/risk ratio of this technique in the field of arterial hypertension. In 2012, this expert consensus propose to limit renal denervation technique to patients with essential hypertension uncontrolled by four or more antihypertensive therapies with at least one treatment being a diuretic and spironolactone at a dose of 25mg shown to be unable to control blood pressure. Measurement of office BP should be at least with SBP more than 160mmHg and/or DBP more than 100mmHg confirmed by ambulatory BP measurement (home or ABP measurement with SBP more than 135mmHg and DBP more than 85mm during daytime period). Finally, renal artery anatomy and function should allow proper intervention (i.e., two functional kidneys, absence of previous renal angioplasty). Renal enervation is a complex interventional procedure with potentially arterial complications, training is required for practitioners. Antihypertensive treatment should not be interrupted immediately after renal denervation since blood pressure lowering effect are delayed and reached maximum effect after 3 months. Monitoring of blood pressure, renal function and anatomy of renal arteries is required 12 months and 36 months after procedure. The expert consensus requires the inclusion of patients experiencing this procedure in a observational study with record form and follow-up.     

Results of prospective randomized controlled trials of transmyocardial laser revascularization

Over 6,000 patients worldwide have undergone transmyocardial laser revascularization (TMR) for the treatment of myocardial ischemia due to end-stage coronary artery disease since 1990. Four prospective randomized controlled trials have reported their results in comparing TMR to maximum medical therapy. All of the trials demonstrated that TMR provided significant relief of angina when compared to medical management. Additional objective data in the form of exercise tolerance and myocardial perfusion scanning was used to support the symptomatic improvement. Recent reports of the failure of percutaneous transmyocardial laser revascularization (PMR) to provide angina relief greater than that seen in a placebo group underscore the need for better understanding of TMR. While all of these trials are similar, they are not identical and this review provides an update and comparison of the results.     

Lipid metabolism in chronic kidney disease: the role of statins in cardiovascular risk.

In the general population, the relation between lipids and cardiovascular disease is clearcut, whereas it is highly controversial in chronic kidney disease (CKD) patients. This is primarily due to diverging results of retrospective observational trials. This study design often encounters confounding, especially in renal disease patients. Even if analyses are corrected for multiple influences, there might be unknown confounders changing the results. Prospective randomized trials assure that groups are comparable except for the intervention used. Confounding is eliminated by randomization. Nevertheless, the lipid discussion was restarted when two randomized, placebo-controlled, interventional trials on lipid-lowering therapy in renal patients have been published (Assessment of Lescol in Renal Transplantation and 4D Study [Atorvastatin in patients with type 2 diabetes on hemodialysis]). Surprisingly, both showed no significant reduction of the primary endpoint by statin therapy. In addition to other factors, this might be due to an altered pathogenesis of atherosclerosis in renal patients where multiple nontraditional cardiovascular risk factors are to be mentioned and different characteristics of cardiovascular disease with a high proportion of sudden cardiac death are present. This review will focus on dyslipidemia in renal failure and its treatment. The data published so far is summarized and grouped according to the different stages of CKD.     

Current status of the management of symptomatic intracranial atherosclerotic disease: the rationale for a randomized trial of medical therapy and intracranial stenting

Stenting and Aggressive Medical Management for Preventing Recurrent stroke in Intracranial Stenosis (SAMMPRIS) is a randomized trial comparing aggressive medical management alone with aggressive medical management in combination with angioplasty and stenting using the Gateway-Wingspan system in patients with symptomatic, high-grade, intracranial stenosis. This trial represents a landmark in the maturation of the field of neurointervention, establishing a foundation for evidenced-based practice. We review the natural history of symptomatic intracranial stenosis when treated medically, the available interventional therapies and the rationale for the design of the SAMMPRIS trial.     

Prospective,double-blind,randomized placebo-controlled trials in interventional spine: what the highest quality literature tells us

Background contextThe prospective, double-blind, randomized, placebo-controlled study design is essential in the interventional spine literature to truly evaluate whether or not a procedure is effective.PurposeThis article will critically evaluate the highest quality interventional spine literature with strict interpretation of the results of these trials.Study designReview article.MethodsExtensive Medline/Pubmed searches and searches of the large review articles on the major interventional spine topics were performed to find all prospective, double-blind, randomized placebo-controlled trials in the English language interventional spine literature.ResultsFluoroscopically-guided lumbosacral transforaminal epidural corticosteroid injections are effiective in the treatment of acute/subacute lumbosacral radicular pain, and in preventing future surgeries. Injection of corticosteroid or Sarapin on the cervical or lumbar medical branch nerves is not effective. When done with proper technique, percutaneous radiofrequency lumbar and cervial medial branch neurotomy are both effective. Intraarticular sacrociliac joint corticosteroid injections are effective in patients with spondyloarthropathy. IDET is modestly effective in the treatment of lumbosacral discogenic pain in carefully selected patients. Percutaneous radio frequency neurotomy of the ramus communicans is effective in the treatment of lumbosacral discogenic pain. No firm conclusions can be drawn about cervical epidural corticosteroid injections, lumbosacral epidural corticosteroid injections for the treatment of chronic radicular pain, cervical or lumbosacral intraarticular zygapophysial joint corticosteroid injections for the treatment of degenerative zygapophysial joint pain, or intradiscal corticosteroid injections.ConclusionsThe prospective, double-blind, randomized placebo-controlled trials in the interventional spine literature demonstrate efficacy from several different procedures when properly performed on appropriate patients. Other procedures have been shown to lack efficacy, while inconclusive evidence exists from multiple other interventional spine procedures. Further details are discussed in the text.     

Continuing uncertainty about the value of percutaneous revascularization in atherosclerotic renovascular disease: a meta-analysis of randomized trials.

BACKGROUND:To study the effect of revascularization on blood pressure (BP) and serum creatinine (SCr) in patients with atherosclerotic renovascular disease (ARVD). METHODS:Three randomized studies comparing balloon angioplasty (plus medication if necessary) with medical therapy alone in patients with ARVD were identified. In one study, patients were stratified and analysed according to whether they had unilateral or bilateral disease. Therefore, four sets of results were available for inclusion in a meta-analysis comparing BP and SCr at 6 months and changes from baseline. RESULTS:The three trials recruited 210 patients. There was no clear benefit for angioplasty when comparing BP at 6 months. Relative to the medical therapy group, the mean (95% CI) systolic/diastolic BP was 2.9 mmHg (-9.1, 3.4)/0.35 mmHg (-3.6, 2.9) lower in the angioplasty group (P=0.4/0.8). There was, however, some suggestion of benefit for angioplasty when changes in BP were compared. There was a greater reduction in the systolic/diastolic BP in the angioplasty group, with a difference of 6.3 mmHg (-11.7, -0.8)/3.3 mmHg (-6.2, -0.4) in the mean change (P=0.02/0.03). There was some suggestion of benefit for angioplasty in terms of changes in SCr, although this was not significant (P=0.06). CONCLUSIONS:The reported trials have been too small to determine reliably the role of angioplasty in ARVD. Although the combined results of three previous trials exclude the possibility of a large improvement in renal function or hypertension after angioplasty, a moderate but clinically worthwhile benefit cannot be ruled out. Further large-scale randomized evidence is needed.     

Coronary Artery Disease in patients with End-Stage Kidney Disease; Current perspective and gaps of knowledge

Coronary artery disease (CAD) is very common in dialysis patients. One third have preexisting CAD and another one third have significant occult disease at the time of starting dialysis. Symptoms are often absent or are atypical, emphasizing the need for vigorous screening, specifically in patients awaiting transplant. The lesions tend to be heavily calcified, diffuse, and involve multiple vessels, consequently, percutaneous coronary interventions are more complicated to perform, and are less successful in achieving and maintaining short- and long-term patency. Dialysis patients have been excluded from the randomized controlled trials on which the current standards for managing CAD have been established. Due to differences in pathobiology and risks and benefits, it is uncertain that the results of these clinical trials extrapolate to patients with advanced chronic kidney disease (CKD). Here we review the data from observational studies and identify special considerations concerning the diagnosis and management of CAD in dialysis patients, including the use of noninvasive functional testing vs anatomical testing, the management of acute coronary syndromes and of stable coronary artery disease, the role for percutaneous revascularization vs coronary artery bypass grafting, and of platelet inhibitor therapy after coronary stenting. We review the preliminary results of the recently published ISCHEMIA-CKD trial, the only trial to date to involve large numbers of dialysis patients. This is the first of, hopefully, many trials in the pipeline that will examine therapies for CAD specifically in patients with advanced CKD, a growing population that is at particularly high risk for poor outcomes.     

Atherosclerotic renovascular disease: medical therapy versus medical therapy plus renal artery stenting in preventing renal failure progression: the rationale and study design of a prospective, multicenter and randomized trial (NITER)

BACKGROUND: Many studies suggest a major prevalence of atherosclerotic renovascular disease (ARVD), caused by mono or bilateral renal artery stenosis (RAS). Unfortunately, there is no definite therapy to cure this disease to date; therefore, ARVD is burdened by important clinical complications with high social and economic costs. The last few years have seen important advancements in both medical therapy and in interventional radiology (for example, percutaneous transluminal renal artery stenting (PTRS)). All of them could affect, in some way, the natural history of ARVD, but to date the optimal strategy has not been established. METHODS: The protocol of a prospective, multicenter, randomized trial "Nephropathy Ischemic Therapy (NITER)" is presented. It enrolls patients with stable renal failure (glomerular filtration rate (GFR) >or=30 ml/min) and hypertension, and hemodynamically significant atherosclerotic ostial RAS (>or=70%) diagnosed by duplex Doppler (DD) ultrasonography and confirmed by magnetic resonance angiography (MRA). This study aims to evaluate whether medical therapy plus interventional PTRS is superior to medical therapy alone according to the following combined primary endpoint: death or dialysis initiation or reduction by >20% in estimated GFR after 0.5, 1, and 2 yrs of follow-up and an extended follow-up until the 4th year. Medical therapy means drugs to control hypertension, improve dyslipidemia and optimize platelet anti-aggregant therapy. The sample size is estimated in 50 patients per group to achieve a statistical significance of 0.05 in case of a reduction by 50% in the combined endpoints.     

Transcatheter therapy for the treatment of atherosclerotic renal artery stenosis

The preemptory challenge in this invited review was to provide a contemporary evidence-based analysis of how renal artery intervention effects renal function and hypertension while also addressing the efficacy in transplanted kidneys. The authors tailored the paper architecture in a way that provides a systematic review of the randomized and observational data relating to the impact of renal stenting in each of these clinical domains. When appropriate the aujthors include data from their experience with over 1 200 renal stent procedures. This contemporary literature review provides objective insight into the procedural risk and early outcomes following renal intervention based on observational study RESULTS: However, well-controlled randomized trials and standardization of interventional technique with or without embolic protection is desperately needed.     

Debate over patient-centered care: Percutaneous coronary intervention or coronary artery bypass grafting?

Coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) have developed as effective therapies to treat coronary artery disease. Initial CABG is associated with lower mortality than initial medical management, especially among high- and intermediate-risk patients with coronary artery disease. However, PCI is currently the most frequent initial treatment delivered by interventional cardiologists to treat multivessel coronary artery disease, despite substantial evidence from meta-analyses of randomized trials and registry data favoring CABG. Recent advancements in PCI did not result in detectable improvements in death or myocardial infarction compared with medical therapy, although significant reductions in target lesions or vessel revascularization were identified after implantation of a drug-eluting stent (DES) rather than a baremetal stent. The SYNTAX trial compared patients with left main and/or three-vessel coronary artery disease treated with DES or CABG. The results of the trial demonstrated the 1-year inferiority of PCI compared with CABG with respect to major adverse cardiac and cerebrovascular events. Nevertheless, patients with coronary artery disease continue to receive more recommendations for PCI and fewer for CABG than are indicated in the guidelines. A multidisciplinary team approach should be the standard of care when recommending interventions for treating complex coronary artery disease among patients for whom CABG is superior in terms of survival and freedom from reintervention.     

Resolution of Renal Failure 1 Month After Onset through Angioplasty of Renal Artery Stenosis

Abstract

The stent placement in patients with atherosclerotic renal artery stenosis and impaired renal function (STAR) and revascularization versus medical therapy for renal-artery stenosis (ASTRAL) trials concluded that renal artery angioplasty was not superior to medical management in delaying progression to renal failure or controlling blood pressure in a selected population. There were several criticisms of the STAR trial’s methodology, and an important criticism of ASTRAL was that the patient was excluded if their clinician was uncertain of the value in correcting the stenosis. Anuric renal failure by renal artery stenosis is a rare occurrence and falls outside this criteria.