Management of Renal Artery Stenosis: 2010

Renal artery stenosis (RAS) is a relatively common manifestation of atherosclerosis, although in a small percentage of cases it is due to fibromuscular dysplasia and less frequently may have other etiologies. RAS may be treated by revascularization, using either percutaneous or open surgical techniques. Currently, technical success with percutaneous revascularization utilizing angioplasty and stenting is achieved in 95% or more of cases in which it is attempted. Despite this, at least one third of patients undergoing renal artery stenting do not receive any measurable benefit. Furthermore, randomized trials of stenting for RAS have failed to demonstrate a benefit over medical management alone. Thus, the clinician is faced with a challenge when determining how to manage an individual patient with RAS. In the current era, all patients with RAS should receive “optimal medical therapy.” This approach should use medicines to control blood pressure, and specifically utilize agents proven to reduce cardiovascular morbidity and mortality. Other components of “optimal medical therapy” include the use of anti-platelet drugs such as aspirin and statins to minimize progression of atherosclerosis. In addition to these strategies, consideration should be given to revascularization therapy. When deciding to revascularize RAS, the patient should have an appropriate clinical indication, in addition to a significant anatomic stenosis. Importantly, stents should not be placed due to the “oculostenotic reflex.” Specifically, patients who continue to have uncontrolled blood pressure or worsening renal function despite an aggressive approach with medical therapy may be particularly good candidates for renal artery stenting. Despite the lack of benefit in randomized trials to date, there is likely still a role for renal artery stenting in RAS; however, careful patient selection is essential to maximize the potential benefit.     

Treating Renal Artery Stenosis

Renal artery stenosis (RAS) leading to hypertension or ischemic nephropathy can be treated by endovascular revascularization using balloon angioplasty or stent implantation. Although high technical success rates > 95%, relatively low frequencies of complications and good long-term patency can be achieved, the indications for interventional treatment are a matter of ongoing debate. Curing hypertension by means of angioplasty rarely occurs, although the number of antihypertensive medication usually can be reduced after successful treatment. Targeting ischemic nephropathy, revascularization can stabilize or at least slow the decline of renal function. Nevertheless, angioplasty also bears the risk of inducing renal deterioration. Careful patient selection remains the most crucial point in renal interventions, however, current data are insufficient to give final recommendations on this issue. The present review focuses on the potential beneficial effects of renal artery PTA and stenting in patients with RAS.     

Management of Atherosclerotic Renal Artery Stenosis: Interventional Versus Medical Therapy

Atherosclerotic renal artery stenosis (RAS) is the most common secondary cause of hypertension, and often results in hypertension that is difficult to control. Atherosclerotic RAS may also result in chronic renal insufficiency, and although controversial, likely leads to end-stage renal failure in a subset of patients. Bilateral RAS, or stenosis to a solitary functioning kidney, has resulted in recurrent episodes of "flash" pulmonary edema and unstable angina pectoris. Despite these serious sequelae of RAS, there remains no consensus on optimal therapy. Invasive therapy (endovascular percutaneous transluminal angioplasty, with or without stent deployment; surgical revascularization) has generated significant interest among interventional physician specialists. However, effective antihypertensive therapy may be a reasonable option in certain scenarios.     

糖尿病患者肾动脉狭窄支架术的疗效

目的评估糖尿病患者肾动脉狭窄支架术后肾功能和血压的变化。方法入选43例糖尿病合并单侧或双侧肾动脉明显狭窄行肾动脉支架术作为糖尿病组,选择同期43例行肾动脉支架术的非糖尿病患者作为对照组。比较两组一般情况、术后肾功能和血压的变化。结果术前糖尿病组血清肌酐和尿β2-微球蛋白水平较对照组明显增高(分别为135±17μmol/L比107±31μmol/L;175±72μg/L比139±57μg/L,P均<0.05),两组肾动脉狭窄程度、支架术成功率相似。术后6个月两组血清肌酐较术前下降,但糖尿病组血清肌酐水平仍明显高于对照组(127±31μmol/L比99±22μmol/L,P<0.05);术后6个月糖尿病组尿β2-微球蛋白含量较术前明显下降(134±17μg/L比175±72μg/L,P<0.05),但在控制血压获益方面较对照组差(44%比71%,P<0.05)。结论糖尿病肾动脉狭窄支架术后肾功能和血压控制改善程度较对照组差。     

冠状动脉病变与肾动脉粥样硬化性狭窄

目的探讨动脉粥样硬化性肾动脉狭窄(ARAS)与脉压及其他相关因素的关系。方法553例入选病例在冠脉造影后行非选择性肾动脉造影,应用多变量Logistic回归分析评价脉压及其他临床因素和ARAS的关系。结果连续3年入选553例患者,24例(4.3%)有轻度肾血管病变(腔径狭窄<50%),84例(15.2%)ARAS(腔径狭窄≥50%),冠心病者ARAS(22.6%vs2.0%)及肾血管病变(5.9%vs1.5%)发生率明显高于非冠心病者。多因素Logistic逐步回归分析显示冠脉狭窄程度、脉压、血肌酐是ARAS发生的独立危险因素。结论ARAS与冠心病冠脉病变程度密切相关。脉压和血肌酐升高是ARAS的独立危险因素。     

冠状动脉病变与肾动脉粥样硬化性狭窄

目的探讨动脉粥样硬化性肾动脉狭窄(ARAS)与脉压及其他相关因素的关系.方法553例入选病例在冠脉造影后行非选择性肾动脉造影,应用多变量Logistic回归分析评价脉压及其他临床因素和ARAS的关系.结果连续3年入选553例患者,24例(4.3%)有轻度肾血管病变(腔径狭窄＜50%),84例(15.2%)ARAS(腔径狭窄≥50%),冠心病者ARAS(22.6%vs 2.0%)及肾血管病变(5.9%vs 1.5%)发生率明显高于非冠心病者.多因素Logistic逐步回归分析显示冠脉狭窄程度、脉压、血肌酐是ARAS发生的独立危险因素.结论ARAS与冠心病冠脉病变程度密切相关.脉压和血肌酐升高是ARAS的独立危险因素.     

动脉粥样硬化性肾动脉狭窄的早期发现

探讨冠状动脉造影同时行肾动脉造影的必要性及动脉粥样硬化性肾动脉狭窄的相关危险因素分析。共 4 91例临床疑似冠心病患者行冠状动脉造影同时行非选择性或选择性肾动脉造影 ,并对相关的临床因素进行评价 ,筛选出动脉粥样硬化性肾动脉狭窄的独立危险因素。冠心病组患者中动脉粥样硬化性肾动脉狭窄的发病率为2 0 % ,显著高于非冠心病组 (2 .6 % )。冠心病、外周血管疾病是动脉粥样硬化性肾动脉狭窄的独立危险因素 (多元Logistic回归分析示 ,P <0 .0 0 1、P =0 .0 0 3) ,是其早期发现的指标。对怀疑有冠心病的患者 ,在冠状动脉造影同时行肾动脉造影有助于动脉粥样硬化性肾动脉狭窄的早期发现。     

Update on Interventions in Renal Artery Stenosis

Noninvasive techniques such as ultrasound and renal scanning have improved the frequency of detection of renal artery stenosis in patients with arterial hypertension, renal insufficiency, or multivascular disease. The results of conventional balloon angioplasty on nonostial renal artery stenoses caused by fibromuscular dysplasia or atherosclerosis showed a high recurrence rate and a moderate impact on the management of hypertension. In patients with ostial lesions, the results of angioplasty were disappointing with low initial success rates and a high rate of restenosis. Other limitations of balloon angioplasty include initial failure or suboptimal result, occluding dissection, and short- or mid-term restenosis. The immediate procedural results of renal artery stenting are excellent, with a low complication rate and satisfactory restenosis rate. Long-term effects on renal function and blood pressure seem to be good. Systematic stent placement is indicated for ostial stenosis. For nonostial lesions, the indication for stent placement may be reserved for residual stenosis or dissection. The indication for a stent would probably be more liberal in cases of bilateral lesions or lesions in a solitary kidney. Multicenter studies probably will be needed to assess the indications and benefits obtained in different clinical and anatomical situations.     

Contrast-Enhanced Doppler Ultrasound of Renal Artery Stenosis

Over the past few years, there has been extensive research for a reliable, noninvasive, and nonionizing imaging method to screen for renal artery stenosis (RAS). Doppler ultrasound (US) is one of many modalities that have been evaluated for the detection of RAS. The lack of standardization in examination protocols and diagnostic criteria, as well as the wide differences in reported accuracy among different laboratories, however, have prevented universal acceptance of this technique as a reliable screening test for RAS. Recently, the introduction of US contrast agents has substantially expanded the potentials of color Doppler US. The use of microbubble echo enhancers in combination with harmonic Doppler imaging has been shown to improve diagnostic confidence by improving the operator's ability to visualize the renal arteries, and to significantly reduce the number of equivocal examinations. In addition, contrast-enhanced harmonic Doppler US can currently provide objective functional assessment of RAS through analysis of time-intensity renal enhancement curve. State-of-the-art contrast-enhanced Doppler US seems to have the potential to become a useful screening test for patients at risk from renovascular hypertension and a tool for follow-up of patients who undergo revascularization procedures.     

Renal Artery Stenosis: Imaging Options,Pitfalls, and Concerns

Renal artery stenosis can be diagnosed with multiple imaging modalities, each one having different risk vs accuracy tradeoffs. Catheter angiography with pressure gradient measurements is the definitive gold standard but also the most invasive and thus reserved primarily for imaging at the time of renal revascularization. Ultrasonography is the safest and least expensive but also the least accurate and most operator-dependent. Contrast-enhanced computed tomographic angiography and magnetic resonance angiography are intermediate (between ultrasound and catheter angiography) with respect to accuracy and expense. Exciting new advances in magnetic resonance that include new contrast agents, which eliminate nephrogenic systemic fibrosis risk, and techniques to characterize the hemodynamic significance of renal artery stenoses are now becoming available. In addition, magnetic resonance angiography without any contrast has become more accurate and rivals contrast-enhanced techniques in some patients. This review explores these techniques for renal artery stenosis imaging.