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.     

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.     

Treatment of renovascular disease and of renovascular hypertension

ABSTRACT: Treatment of occlusive lesions of renal arteries, defined as renovascular disease (RVD), is aimed both at preventing ischemic renal disease (IRD) and rescuing renal function through revascularization procedures, such as PTRA, endovascular stenting and surgical revascularization, as well as curing or improving hypertension in the presence of renovascular hypertension (RVH), i.e. hypertension caused by these vascular lesions. Preventive treatment of IRD is still an individual decision making process based on the type of renal lesions, degree of renal stenosis and progressive loss of renal mass as well as on immediate and late technical success of revascularization procedures together with their rate of complications. Rescue of renal function and-or prediction of the outcome of renal function after successful revascularization depends not only on the possibility of clarifying whether the decrease in renal function is a functioning-reversible phenomenon linked to renal hypoperfusion but also on the potential risk that the revascularization procedure may induce irreversible kidney damage. The rationale for treating RVH through revascularization procedures derives from the possibility of establishing a pathogenetic link between the occlusive lesions and hypertension, mainly through renal vein renin measurement and captopril renography and possibly their combination. Finally, medical treatment of hypertension is needed in patients who cannot undergo or refuse revascularization and whose blood pressure is not normalized by these procedures.     

Percutaneous coronary intervention in chronic kidney disease patients

Cardiovascular disease (CVD) is the major cause of morbidity and mortality in patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD). The increased prevalence of CVD in patients with renal dysfunction has been attributed to lack of effective prevention and low utilization of effective therapy. The optimal treatment of ischemic heart disease in ESRD patients before renal transplantation is controversial. Although no meta-analysis or pooled analysis of the data from small trials exists, it appears that percutaneous coronary intervention (PCI) provides excellent angiographic success but is associated with increased restenosis and the need for revascularization and that coronary artery bypass grafting (CABG), while associated with higher in-hospital morbidity and mortality, provides better overall long-term results and freedom from angina. Despite suboptimal results for percutaneous interventions in comparison with bypass surgery, PCI remains a viable option, especially for patients who are not candidates for surgery and those with disabling angina despite anti-anginal therapy. Regardless of the revascularization strategy used, outcomes of CABG or PCI in these patients are significantly worse than outcomes in the general population. The long-term benefit after revascularization and adjunctive medical therapy should be an area of intense future research. Studies should also be conducted to investigate the benefit and safety of therapies such as the long-term use of beta-blockers, statins, and renin-angiotensin-aldosterone axis inhibition in patients with CKD.     

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.     

132例动脉粥样硬化性肾动脉狭窄临床分析

目的探讨动脉粥样硬化性肾动脉狭窄(ARAS)患者的临床特点,评价介入治疗和单纯药物治疗对肾功能预后的影响。方法分析本院经肾动脉造影确诊的ARAS患者132例的临床资料。88例单侧ARAS按年龄≤70岁和>70岁分组及按基础GFR≥60 ml／min和GFIR< 60 ml／min分组,比较介入治疗和药物治疗对GFR的影响。44例双侧ARAS按行双侧、单侧、非介入治疗分组,比较3组差异。结果单侧ARAS、年龄≤70岁者,介入治疗1年后GFR变化值优于药物治疗组(P<0．05);基础GFR≥60 ml／min者,介入治疗1年后GFR变化值优于药物治疗组(P<0．05);年龄>70岁,GFR<60 ml／min者,介入治疗与药物治疗相比,GFR变化值无显著性差异。双侧ARAS者双侧介入治疗GFR变化值优于单侧介入,单侧介入优于非介入治疗组。Logistic回归分析示基础GFR≥60 ml／min,进行介入治疗的单侧AKAS者,肾功能(GFR)的预后较好。结论单侧ARAS年龄≤70岁,介入治疗前GFR≥60 ml／min者,介入治疗后肾功能 (GFR)预后较好;年龄大于70岁的患者,介入前应仔细评估,慎重选择介入治疗。     

Diagnosis and therapy of atheromatous renal artery stenosis

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

Renal artery revascularization: collaborative approaches for specialists

Endovascular revascularization for atherosclerotic renal artery stenosis (RAS) is the revascularization strategy of choice for patients with hemodynamically and clinically significant renal artery stenosis. Surgical revascularization is reserved for failed endovascular therapy or concomitant abdominal aortic surgery. Endovascular renal artery stenting is associated with excellent technical success, low complication rates, and acceptable long-term patency. This technique has been proven to be beneficial for preserving kidney function and stabilizing or improving blood pressure control in selected patients. Nevertheless, deterioration in kidney function after the procedure in 10% to 20% of cases may limit the immediate benefits of this technique. Atheroembolism appears to play an important role in the cause of kidney dysfunction after renal revascularization. Renal revascularization with a distal embolic protection device is a promising strategy in reducing the risk of atheroembolism and deterioration in kidney function.     

Surgical correction of renovascular hypertension

The role of surgical revascularization in the management of patients with renal artery disease has changed in recent years. This has occurred owing to the advent of transluminal angioplasty as an effective method of treatment for certain patients, improved results of surgical revascularization in older patients with atherosclerosis, an enhanced appreciation of advanced atherosclerotic renal artery disease as a correctable cause of renal failure, and the development of more effective surgical techniques for patients with severe aortic atherosclerosis and branch renal artery disease. Surgical revascularization is at present the treatment of choice for patients with branch renal artery disease, ostial atherosclerotic renal artery disease, a renal artery aneurysm, and patients in whom renal angioplasty has been unsuccessful. Excellent clinical results continue to be achieved with surgical revascularization in properly selected patients.     

Diagnostic criteria for renovascular disease: where are we now?

Renovascular disease, especially atherosclerotic renal artery stenosis (ARAS) in older subjects, is commonly encountered in clinical practice. This is at least in part due to the major advances in non-invasive imaging techniques that allow greater diagnostic sensitivity and accuracy than ever before. Despite increased awareness of ARAS, renal revascularization is less commonly performed, likely as a result of several prospective, randomized, clinical trials which fail to demonstrate major benefits of renal revascularization beyond medical therapy alone. Primary care physicians are less likely to investigate renovascular disease and nephrologists likely see more patients after a period of unsuccessful medical therapy with more advanced ARAS. The goal of this review is to revisit current diagnostic and therapeutic paradigms in order to characterize more clearly which patients will likely benefit from further evaluation and intensive treatment of renal artery stenosis.     

Evaluation and preparation for surgical treatment of renal artery disease

The diagnosis of renovascular disease and renovascular hypertension is outlined. A comparison and analysis of the advantages of three forms of treatment are made. These include medical management, percutaneous transluminal coronary angioplasty, and surgical intervention. Selection of patients for revascularization to preserve renal function is discussed, and guidelines for determining renal salvageability are presented. Surgical revascularization is the treatment of choice for patients with ostial atherosclerotic renal artery disease, branch renal artery disease, or a renal artery aneurysm.     

Captopril renal scintigraphy--an advance in the detection and treatment of renovascular hypertension

Despite the risks associated with renovascular hypertension and the durable benefits of revascularization, the detection of patients with renovascular hypertension and the selection of those who will benefit from interventional therapy remains a challenge. We have previously documented the reliability of captopril renal scintigraphy in predicting angiographically significant renal artery stenosis in patients suspected of having renovascular hypertension. In the present study we report our recent experience with this noninvasive technique in predicting outcome after revascularization. Captopril renal scintigraphy involves the administration of 50 mg of captopril 3 hours after a baseline technitium-99m diethylenetriaminepentaacetic acid renal scan and 1 hour before a repeat captopril renal scintigraphy scan. Nineteen of the last 70 patients with clinically suspected renovascular hypertension undergoing captopril renal scintigraphy had abnormal renal scan outcomes, and 17 had a decrease in flow or function after captopril (positive captopril renal scintigraphy). Eight of these 17 with abnormal findings on captopril renal scintigraphy underwent revascularization, and the hypertension was cured or improved in six of the eight: two of three after surgical bypass grafting and four of five after angioplasty. In the seven surviving patients with abnormal renal scan results but no change with captopril (negative captopril renal scintigraphy), improvement in hypertension after treatment occurred in only one: one of two after nephrectomy, zero of three after bypass surgery, and zero of two after angioplasty (p less than 0.05). We conclude that captopril renal scintigraphy is an accurate predictor of hypertension response to revascularization. Further evaluation of this new noninvasive technique for assessing patients with suspected renovascular hypertension appears warranted.     

3 R study: renal outcome in renal ischemia: revascularisation or medical treatment

Ischemic nephropathy refers to the kidney damage following stenosis or an obstructive lesion in the main kidney arteries. This disorder has been overlooked in the past and a more rational and specific use of clinical criteria, and the development of not very invasive techniques with a good diagnostic accuracy such as spiral CT angiography, NMR angiography and echo-colour-Doppler have improved our ability to identify these patients. It is therefore likely that, in the next few years, we will find ourselves treating an increasing number of patients with renovascular ischemic disorders. Transluminal angioplasty and, more recently, the use of endovascular stents, have led to a marked improvement in the treatment of stenoses and, together with vascular surgery, allow to treat almost all patients with this disorder. There is, however, a lack of prospective and controlled studies, which demonstrate the long term benefit of revascularization treatment, as compared with optimum conservative treatment in reducing cardiovascular mortality, cardiovascular events and preserving renal function. The Ischemic Nephropathy Study Group of the Italian Society of Nephrology has organized a prospective, controlled study over a period of three years, aimed at comparing the effect of revascularization versus medical therapy in 300 patients with renal artery stenosis, ranging between 50 and 90 per cent, who will be randomly assigned to the two treatments. End point will be cardiovascular mortality and morbidity and need for renal replacement therapy.     

Surgical renal artery reconstruction after percutaneous transluminal angioplasty

Percutaneous transluminal renal angioplasty (PTRA) is a controversial treatment for renal artery stenosis. This article discusses whether or not a prior attempt at PTRA compromises a subsequent elective or emergent surgical revascularization. Thirteen patients had surgical renal artery reconstruction after one or more PTRAs. Eight of the patients were treated because of atherosclerotic renal artery disease whereas five had a form of fibromuscular dysplasia. Five patients had renal artery injury directly related to the angioplasty. Four of these kidneys were saved. Eight patients were treated from 6 to 920 days after PTRA because of recurrent stenosis or occlusion of the renal artery. Only one of these kidneys was lost, an attempt at revascularization of a small kidney that failed to resume function. A prior attempt at PTRA did not compromise the ability of subsequent surgical revascularization to ameliorate hypertension. We conclude that surgical renal revascularization is not made less likely to succeed by a previous attempt at PTRA; even if the renal artery is thrombosed or perforated during the procedure, a reasonable chance of renal salvage is obtained by immediate surgical revascularization.     

Management of peripheral vascular disease compromising renal allograft placement and function: review of the literature with an illustrative case

As the average age of a renal transplant candidate increases, the challenge of managing recipient vascular disease affecting renal allograft function will become more common. Pre-operative screening can reveal the presence of atheromatous disease that could adversely affect allograft transplantation and function, but parameters for successful screening have not been established. Treatment options include pre-operative revascularization, concurrent therapy or delayed revascularization. Endovascular therapies have burgeoned but surgical correction is still required for some of the more complex, long-segment lesions. Potential surgical interventions range from endarterectomy to aorto-iliac bypasses. We present a case of immediate post-operative revascularization using a femoro-femoral bypass to salvage a renal allograft. The literature is reviewed to assess best practices for detecting peripheral vascular disease in renal transplant candidates and subsequent management options.     

On-pump versus off-pump coronary artery bypass grafting: impact on postoperative renal failure requiring renal replacement therapy

BACKGROUND: Despite refinements in perioperative patient management postoperative renal failure requiring hemofiltration or dialysis is still a common complication after coronary artery bypass grafting associated with impaired patient outcome. METHODS: Prospective data on 9,631 patients receiving myocardial revascularization with (coronary artery bypass grafting [n = 8,870]) or without cardiopulmonary bypass (off-pump coronary artery bypass grafting [n = 761]) between April 1996 and August 2001 were evaluated by univariate and multivariate logistic regression analysis. RESULTS: Overall prevalence of postoperative continuous renal replacement therapy was 4.1% (coronary artery bypass grafting, 4.3%; off-pump coronary artery bypass grafting, 1.8%; p = 0.001). Thirty of 40 selected preoperative and intraoperative patient and treatment related variables had a high association with the requirement for postoperative renal replacement therapy; fifteen of these variables were independent predictors in the whole study population. Off-pump coronary artery bypass surgery was identified as having a significantly lower predictive value for postoperative continuous renal placement therapy. In the subgroup of patients undergoing off-pump coronary artery bypass grafting surgery, a second multivariate logistic regression model revealed preoperative cardiogenic shock, urgent operation, intraoperative low cardiac output, and high transfusion requirement as independent predictors for postoperative renal replacement therapy. CONCLUSIONS: Patients with preoperative nondialysis dependent renal insufficiency are at a high risk for further decline in renal function requiring postoperative continuous renal replacement therapy. Off-pump coronary artery bypass surgery is associated with a lower prevalence of postoperative renal replacement therapy after coronary artery bypass grafting.     

Simultaneous aortic and renal artery reconstruction

Nine patients presenting with combined aortic and renal artery disease underwent simultaneous infrarenal aortic reconstruction and renal revascularization. Seven patients had aneurysmal and two had occlusive aortic disease in association with unilateral (four cases) or bilateral (five cases) atheromatous renal artery stenosis. The indications for renal revascularization were hypertension (n = 8) refractory to medical treatment or associated with renal functional impairment and chronic renal failure alone (n = 1). Five patients developed postoperative complications with one fatality. Eight patients were followed up for between 7 months and 4 years. Control of blood pressure had improved in six of seven hypertensive patients. Serum creatinine levels were stabilized or had fallen in five patients. Simultaneous aortic and renal artery reconstruction is widely recognized as having a high postoperative morbidity rate but can improve control of hypertension and stabilize renal function in carefully selected patients.     

Improved results of vascular reconstruction in pediatric and young adult patients with renovascular hypertension

From 1955 to 1988, 56 patients 21 years old or younger underwent surgical treatment for renovascular hypertension at our clinic. The cause of renal artery disease was fibrous dysplasia in 53 patients, Takayasu's arteritis in 2 or an arterial aneurysm in 1. Bilateral or branch renal artery disease, and extrarenal arterial disease were present in 16, 23 and 11 patients, respectively. The results of 28 patients treated from 1955 to 1977 (group 1) were compared to those of 28 patients treated from 1978 to 1988 (group 2). Hypertension was cured or improved postoperatively in 83% of the patients from group 1 and in 96% from group 2 (p = 0.07). However, this outcome was achieved through surgical revascularization in only 48% of the patients from group 1 compared to 96% from group 2 (p = 0.0002). A multivariate analysis revealed that the only significant variable related to clinical outcome was the era of treatment, which reflects the improved technical efficacy of revascularization during the last decade. Aortorenal bypass and renal autotransplantation have emerged as the preferred revascularization operations. It currently is possible to achieve amelioration of hypertension and preservation of renal function in most young patients with renal artery disease.     

Atherosclerotic renal artery stenosis: current status and future directions

PURPOSE OF REVIEW: Atherosclerotic renal artery stenosis is a common, progressive problem that increases in prevalence with age. It can have important clinical consequences such as hypertension, pulmonary edema, and renal failure. In addition, it is associated with increased cardiovascular mortality. The purpose of this review is to describe the current status of knowledge and future directions for this evolving field. RECENT FINDINGS: In patients who are suspected of having the disease, duplex Doppler ultrasound and magnetic resonance angiography remain the most promising noninvasive screening tests. Percutaneous revascularization continues to advance, and technical success is possible in the vast majority of patients. Revascularization for hypertension is of modest clinical benefit. Limited information is available on the effect of revascularization on preservation of renal function or cardiovascular events and mortality. SUMMARY: Further studies are still needed focusing on the identification of which patients will derive benefit from percutaneous revascularization and whether intervention provides an advantage over medical therapy, particularly with respect to preservation of renal function and reduction in cardiovascular morbidity and mortality.     

Therapeutical aspects of intrarenal artery aneurysms

The relative infrequency of aneurysms of the branches of the renal artery produces some indecision as to the surgeon's therapeutical choice. The purpose of this study is to carefully examine the indications for surgical treatment and to select precise therapeutical criteria on the basis of 8 patients in whom aneurysms of the main renal artery or of its branches were diagnosed from 1978 to 1986. In 1 patient, the disease was bilateral with a ruptured main artery aneurysm. 5 aneurysms were treated surgically (the ruptured one by nephrectomy, 2 by ex situ revascularization and 2 by in situ revascularization). In the remaining cases, only periodical controls were performed. In 4 surgically treated patients, angiographic follow-up demonstrated a regular renal revascularization and in 1 patient a thrombosis on the site of the anastomosis. On the basis of personal experience, surgical treatment is required for aneurysms larger than 1.5 cm in size without or with partial calcification, aneurysms occurring in pregnant women or in patients likely to conceive in the future, expanding aneurysms, and renin-mediated hypertension. The introduction of microsurgical techniques and renal preservation makes it possible for the urologist to chose between various therapeutical means for the treatment of intrarenal aneurysms. Reconstruction of anatomical continuity of the arterial supply avoiding unnecessary operative demolishment is feasible.