Atherosclerotic renal artery stenosis

Opinion statement The clinical diagnosis of renal artery stenosis relies on a high index of suspicion and confirmation by noninvasive imaging modalities. There are three distinct clinical syndromes associated with renal artery stenosis: renin-dependent hypertension, essential hypertension, and ischemic nephropathy. Clinical features that should heighten suspicion for renal artery stenosis include abrupt-onset or accelerated hypertension at any age, unexplained acute or chronic azotemia, azotemia induced by angiotensin-converting enzyme (ACE) inhibitors, asymmetric renal dimensions, and congestive heart failure with normal ventricular function. Patients with true renin-dependent (renovascular) hypertension are typically young or middle-age women with renal fibromuscular dysplasia (FMD). Initial therapy for renovascular hypertension associated with FMD is an ACE inhibitor; refractory hypertension responds readily to balloon angioplasty without stenting. Elderly patients with generalized atherosclerosis and hypertension often have atherosclerotic renal artery stenosis (ARAS); hypertension in these patients is usually not renin dependent (ie, essential hypertension). Hypertension alone, even if treated with multiple medications, is not a compelling indication for renal artery revascularization; these patients should be treated aggressively with antihypertensive medical therapy. Renal artery revascularization with stenting may be considered for refractory severe hypertension, and would be expected to improve blood control and modestly reduce medication requirements. Renal revascularization rarely cures hypertension in patients with ARAS. Patients with ARAS, hypertension, and end-organ injury should be considered for renal revascularization. Manifestations of end-organ injury include nonischemic pulmonary edema; hypertensive crisis associated with acute coronary syndrome, aortic dissection, or neurologic impairment; and renal insufficiency. Ischemic nephropathy is best treated before the development of advanced renal failure. The best candidates for revascularization are those with baseline serum creatinine less than 2.0 mg/dL, bilateral renal artery stenosis, normal renal resistive indices, no proteinuria, and one or more manifestations of end-organ injury. In these patients, renal revascularization is best accomplished by stenting, although surgical revascularization may be considered in patients with concomitant severe aortic aneurysmal or occlusive disease.     

Percutaneous transluminal renal stenting for transplant renal artery stenosis

Objectives : Renal transplantation is a well‐accepted therapeutic option for patients with end stage renal disease. Renal artery stenosis occurring in a transplanted kidney is a potentially serious condition and adversely affects graft survival and prognosis. The objective of this study is to document the immediate and intermediate term clinical results of renal stenting in this rare subset of renal artery stenosis. Background: There is limited data about the effectiveness of renal stenting in transplant renal artery stenosis. Methods : Eight patients, aged between 22 and 51 (42.5 ± 9.25) years, were referred to our tertiary care interventional cardiology services for renal intervention. The diagnosis of transplant renal artery stenosis was based on clinical presentation (uncontrolled hypertension (n = 4, 50%), worsening renal function (n = 3, 37.5%) or flash pulmonary oedema (n = 1, 12.5%)] and Doppler ultrasound. Results : All patients had live donor renal transplant using end to end anastomosis 2 to 11 (6.25 ± 3.24) months prior to intervention. Angiography revealed discrete stenosis at the anastomotic site. Intrarenal stenting performed from femoral access using 6 F accessories produced excellent angiographic results. There were no access site or procedure related complications. The intervention produced excellent immediate and intermediate term clinical results. In three patients, there was stabilization of renal function during 62 ± 9.16 months of follow‐up with decrease in serum creatinine by 38.86 ± 6.62 %; P = 0.0476. In four patients with refractory hypertension, excellent blood pressure control was achieved with a reduction in mean blood pressure by 25.95 ± 5.48 mm Hg (from 122.4 ± 5.7 to 96.45 ± 2.45 mm Hg; P = 0.0002) during 65.25 ± 23.79 months follow‐up. There was decrease in antihypertensive drug requirement from 3.75 ± 0.5 to 1.75 ± 0.5. During follow‐up, Doppler ultrasound documented a high peak systolic velocity in one asymptomatic patient with well controlled blood pressure and preserved renal function. Sustained benefits of percutaneous revascularization were supported by normal Doppler parameters in the remaining patients. Conclusions : Percutaneous renal stenting provides excellent angiographic and clinical results sustained at intermediate term follow‐up in patients with symptomatic transplant renal artery stenosis. © 2011 Wiley‐Liss, Inc.     

Suprarenal artery stenosis may be mistaken for renal artery stenosis in Doppler studies

There are several limitations in using colour-flow-Doppler (CFD) to diagnose renal artery stenosis. This report describes a case of "false positive" stenosis of the renal artery diagnosed using CFD. A patient affected by arterial hypertension and with a suspected stenosis of the renal artery was examined using CFD. However, the patient was in fact suffering from suprarenal artery stenosis.     

Catheter-based therapy for atherosclerotic renal artery stenosis

The prevalence of atherosclerotic renal artery stenosis (RAS) is more common than was previously thought, particularly in patients with known coronary, cerebrovascular, or peripheral vascular atherosclerosis. Clinical subsets in which RAS is more common include patients with uncontrolled hypertension, renal insufficiency, and/or sudden onset ("flash") pulmonary edema. Renal artery atherosclerosis progresses over time and is associated with loss of renal function regardless of medical therapy. Patients with symptomatic (hypertension, renal insufficiency, or flash pulmonary edema) and hemodynamically significant RAS are potential candidates for revascularization. The current standard of care is stent placement for aorto-ostial atherosclerotic lesions. Procedure success rates are very high (> or =95%), with infrequent major complication rates. Five-year primary patency rates are 80% to 85%, and secondary patency rates exceed 90%. The key element in managing patients with RAS is selecting those most likely to benefit, that is, those with blood pressure control, preservation or improvement of renal function, and control of flash pulmonary edema from renal revascularization. This article will highlight the anatomical features, physiologic parameters, and biomarkers that may be helpful in optimally selecting patients for renal artery revascularization.     

Revascularization in renal artery stenosis

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

对吻技术治疗肾动脉狭窄分叉病变五例

目的探讨对吻球囊技术和对吻支架技术治疗肾动脉狭窄分叉病变的疗效。方法共5例患者采用对吻球囊技术或对吻支架技术治疗粥样硬化性肾动脉狭窄分叉病变。结果 5例患者肾动脉主支参考血管直径(RVD)为(5.6±0.4)mm,分支1RVD为(3.4±0.4)mm,分支2RVD为(3.6±0.5)mm。3例患者采用对吻球囊技术治疗肾动脉分叉病变,并于主支-分支置入支架,均有不同程度的残余狭窄;2例患者采用对吻支架技术治疗肾动脉分叉病变,无残余狭窄。术后随访2例患者血压水平降低,3例患者血压水平无明显变化,其中1例血压水平虽无明显变化,但服用的降压药物种类减少。1例患者术后血肌酐水平显著降低。结论对吻支架技术适用于分叉近端主支血管内径明显大于分叉远端分支血管内径的情况。从有限的经验来看,似乎对吻支架技术与对吻球囊技术相比具有更好的即刻影像学效果。     

Utility of captopril renal scans for detecting renal artery stenosis

BACKGROUND: Captopril renal scanning (CRS) is commonly recommended as a noninvasive method for detecting renal artery stenosis (RAS), based on performance characteristics determined in research settings. Scant data are available, however, regarding the utility of CRS in clinical practice. METHODS: We evaluated the performance characteristics (sensitivity, specificity, and predictive values) of CRS in a consecutive series of 90 patients who underwent both CRS and renal arteriography within a 6-month period (January 1, 1991, through December 31, 1995) at a university hospital. RESULTS: Among 86 eligible patients (and 169 kidneys), the prevalence of RAS was 43%. The sensitivity of CRS was 74% (95% confidence interval [CI], 62%-83%); the specificity was 59% (95% CI, 49%-69%); the positive predictive value was 58% (95% CI, 47%-68%); and the negative predictive value was 75% (95% CI, 64%-84%). Also, there was evidence of spectrum bias, because the sensitivity and specificity (as well as the positive and negative predictive values) were different for groups with and without vascular disease. CONCLUSIONS: The results of CRS were substantially worse in a clinical practice setting than previously reported in research settings, despite a similar prevalence of RAS. Captopril renal scanning should not be used as an initial screening test for diagnosing RAS, even among patients with high clinical likelihood of disease.     

Angiographic index for angioplasty-treatable atheromatous renal artery stenosis

The relative reduction of the lumen diameter by an atheromatous lesion (% diameter reduction) is generally used as an angiographic index for atheromatous renal artery stenosis (ARAS), but its association with the clinical outcome of angioplasty has not been sufficiently evaluated. This study aimed to identify an angiographic index(ices) that can be used to identify angioplasty-treatable ARAS. We evaluated the clinical outcome of angioplasty in 27 patients who had unilateral ARAS without renal insufficiency by assessing the reduction in systemic arterial blood pressure (BP) after angioplasty and examined its association with various angiographic indices. In the receiver operating characteristic analysis for BP reduction, the area under the curve was larger for the absolute value of the lumen diameter at the narrowest part of its constriction (the narrowest diameter), an angiographic index introduced in this study, than for % diameter reduction (0.770 vs. 0.731). At a 3-mm maximum threshold, the narrowest diameter identified cases with BP reduction; the sensitivity/specificity was 0.89/0.75 (p < 0.001). Furthermore, the narrowest diameter correlated better than % diameter reduction with hemodynamic indices of ARAS. In conclusion, the narrowest diameter is an angiographic index that can effectively identify angioplasty-treatable ARAS in patients without renal insufficiency.     

Current methods for diagnosing renal artery stenosis]

PURPOSE: Today, the methods for detecting renal artery stenosis are numerous. They lead to the identification either of anatomic stenosis or functional stenosis (onset of renin-angiotensin system). The purpose of this review is to emphasize the performances, limitations and diagnostic criteria for each technique. CURRENT KNOWLEDGE AND KEY POINTS: For detection of anatomic stenosis, the feasibility of Doppler examination has been increased by the improvement of US systems and the development of contrast agents. However, the criteria used nowadays still need wider evaluation. Helical CT angiography allows a better detection of accessory arteries and calcifications but MR angiography has a better spatial resolution and uses a non-nephrotoxic contrast agent. The performances of these two techniques have never been compared. The choice between these techniques depends on the operators' experience and the availability of the systems. For functional stenosis, detection is now based on captopril-sensitized scintigraphy. FUTURE PROSPECTS AND PROJECTS: It would be necessary to better compare performances and cost-effectiveness ratios of these methods and of the two imaging strategies (detection of anatomic stenosis versus functional stenoses). Probably in the future, MR will gain a major place, providing, in the same imaging session, morphologic and functional data.     

Ostial renal artery stent placement for atherosclerotic renal artery stenosis in patients with coronary artery disease

To test the utility of endoprosthetic treatment for ostial renal artery stenosis, and to examine blood pressure and its treatment, serum creatinine, and restenosis rate, 44 ostial renal stent placements were performed in 30 patients with concomitant coronary artery disease, arterial hypertension, and the indication for angiotensin converting enzyme (ACE) therapy. There was a marked decrease in systolic and diastolic blood pressure (163 ± 30 to 145 ± 17 and 93 ± 18 to 83 ± 10 mm Hg; P < 0.008) with a decrease in number of medication (3.2 ± 0.9 to 2.8 ± 1.0; P = 0.005). In 5 out of 8 patients not receiving an ACE inhibitor, this drug could be added. Serum creatinine changed from 1.46 ± 0.7 mg/dl to 1.39 ± 0.58 mg/dl (P = ns). Three patients showed restenosis (12.5%). Ostial stenting lowers blood pressure, decreases antihypertensive drugs and increases medication flexibility. Cathet. Cardiovasc. Diagn. 45:1–8, 1998. © 1998 Wiley-Liss, Inc.     

Salvage stenting for acute renal failure secondary to renal artery stenosis

We present two cases of successful, emergency renal artery stenting in the setting of acute renal failure requiring dialysis secondary to renal artery stenosis. Early reopening of the stenotic renal artery led to the resolution of acute renal failure and obviated the need for further dialysis in both cases.     

肾动脉狭窄的临床诊断

目的:探讨肾动脉狭窄患者的临床诊断依据和方法。方法:回顾性分析2004年10月至2005年10月在我院介入科行肾动脉造影证实为双肾或单肾肾动脉狭窄患者的临床表现及相关的检查。结果:41例患者经造影证实有双侧或单侧肾动脉狭窄。其中:(1)82.9%(34/41)的患者血压控制不理想;(2)51.22%(21/41)的患者肾超声检查有肾缩小(长径<9cm),80.5%(33/41)患者肾动脉血流峰速>180cm/s;(3)31.7%(13/41)的患者血清肌酐水平升高;(4)仅12.2%(5/41)的患者出现蛋白尿,7.3%的患者有外周血管杂音出现;(5)5例行磁共振成像(MAI)检查均提示有肾动脉狭窄,并经造影证实。结论:肾动脉狭窄的临床表现不典型。血压难控制、超声检查肾脏缩小、血管峰值流速增加(>180cm/s),应高度警惕有肾动脉狭窄可能,进一步行MAI,甚至肾动脉造影检查以明确诊断。