STENOSIS OF RENAL ARTERY: AN UNSELECTED NECROPSY STUDY

Focus on the Most Common Paucisymptomatic Vasculopathic Population, from Diagnosis to Secondary Prevention of Complications

Middle-aged adults can start to be affected by some arterial diseases (ADs), such as abdominal aortic or popliteal artery aneurysms, lower extremity arterial disease, internal carotid, or renal artery or subclavian artery stenosis. These vasculopathies are often asymptomatic or paucisymptomatic before manifesting themselves with dramatic complications. Therefore, early detection of ADs is fundamental to reduce the risk of major adverse cardiovascular and limb events. Furthermore, ADs carry a high correlation with silent coronary artery disease (CAD). This study focuses on the most common ADs, in the attempt to summarize some key points which should selectively drive screening. Since the human and economic possibilities to instrumentally screen wide populations is not evident, deep knowledge of semeiotics and careful anamnesis must play a central role in our daily activity as physicians. The presence of some risk factors for atherosclerosis, or an already known history of CAD, can raise the clinical suspicion of ADs after a careful clinical history and a deep physical examination. The clinical suspicion must then be confirmed by a first-level ultrasound investigation and, if so, adequate treatments can be adopted to prevent dreadful complications.

Atherosclerotic Renal Artery Stenosis: Should we Intervene Earlier?

Purpose of Review

Randomized trials have failed to show clinical benefit in patients with atherosclerotic renal artery stenosis who were treated with angioplasty with or without stenting. However, these studies were done in patients with a high-grade stenosis. This paper examines whether there are arguments to consider patients with low-grade stenosis for angioplasty.

Recent Findings

Patients with low-grade (< 50%) atherosclerotic renal artery stenosis have an excess risk for cardiovascular and renal complications. This could be related to inflammatory factors being generated by the stenotic kidney. Moreover, even a kidney with low-grade stenosis clears less or produces more of the natural nitric oxide inhibitor ADMA.

Summary

Patients with low-grade atherosclerotic renal artery stenosis have an increased risk for a variety of complications. In addition, the abnormality is progressive. There is a case for setting up a prospective trial to examine whether angioplasty confers benefit in patients with low-grade renal artery stenosis.

Meta-analysis of revascularization versus medical therapy for atherosclerotic renal artery stenosis

The aim of the study was to compare the efficacy of revascularization versus medical therapy in patients with atherosclerotic renal artery stenosis (ARAS). ARAS is the most common cause of secondary hypertension and is associated with several complications, such as renal failure, coronary artery disease, cardiac destabilization, and stroke. Medical therapy is the cornerstone for management of ARAS; however, numerous trials have compared medical therapy with revascularization in the form of percutaneous renal artery angioplasty (PTRA) or percutaneous renal artery angioplasty with stent placement (PTRAS). Medline (PubMed and Ovid SP), Embase, Cochrane Central Register of Controlled Clinical Trials (CENTRAL), and Cochrane Database of Systematic Review (CDSR) were searched till present (November 2013) to identify clinical trials where medical therapy was compared with revascularization (PTRA or PTRAS). We performed a meta-analysis using a random effects model. The heterogeneity was assessed using I2 values. The initial database search identified 540 studies and 7 randomized controlled trials, and 2,139 patients were included in the final analysis. Angioplasty with or without stenting was not superior to medical therapy with respect to any outcome. The incidence of nonfatal myocardial infarction was 6.74% in both the stenting and medical therapy group (odds ratio=0.998, 95% confidence interval 0.698 to 1.427, p=0.992), and incidence of renal events in stenting population was found to be 19.58% versus 20.53% in medical therapy (odds ratio=0.945, 95% confidence interval 0.755 to 1.182, p=0.620). In conclusion, PTRA or PTRAS does not improve outcomes compared with medical therapy in patients with ARAS. Future studies should investigate to identify patient subgroups that may benefit from such an intervention.

Analysis of the sensitivity and specificity of noninvasive imaging tests for the diagnosis of renal artery stenosis

BACKGROUND

Aging and atherosclerosis are related to renovascular hypertension in elderly individuals. Regardless of comorbidities, renal artery stenosis is itself an important cause of cardiovascular morbidity and mortality.

OBJECTIVE

To define the sensitivity, specificity, positive predictive value, and negative predictive value of noninvasive imaging tests used in the diagnosis of renal artery stenosis.

METHODS

In a group of 61 patients recruited, 122 arteries were analized, thus permitting the definition of sensitivity, specificity, and the relative contribution of each imaging study performed (Doppler, scintigraphy and computed tomographic angiography in comparison to renal arteriography).

RESULTS

The mean age was 65.43 years (standard deviation: 8.7). Of the variables related to the study population that were compared to arteriography, two correlated with renal artery stenosis, renal dysfunction and triglycerides. The median glomerular filtration rate was 52.8 mL/min/m². Doppler showed sensitivity of 82.90%, specificity of 70%, a positive predictive value of 85% and negative predictive value of 66.70%. For tomography, sensitivity was 66.70%, specificity 80%, positive predictive value 87.50% and negative predictive value 55.20%. With these findings, we could identify the imaging tests that best detected stenosis.

CONCLUSION

Tomography and Doppler showed good quality and efficacy in the diagnosis of renal artery stenosis, with Doppler having the advantage of not requiring the use of contrast medium for the assessment of a disease that is common in diabetics and is associated with renal dysfunction and severe left ventricular dysfunction.

Percutaneous renal artery intervention versus medical therapy in patients with renal artery stenosis: a meta-analysis

AIMS

Patients with renal artery stenosis are treated with percutaneous intervention, but randomised studies are inconclusive. We aimed to compare renal percutaneous revascularisation versus medical therapy.

METHODS AND RESULTS

A systematic search for randomised controlled studies yielded three studies comparing renal angioplasty and two studies comparing renal angioplasty with stenting versus medical therapy, respectively. Six sets of data were extracted focusing on systolic and diastolic blood pressure as well as serum creatinine at follow-up. The five trials included 1,030 patients with renal artery stenosis. There was a trend toward, but no significant improvement in, systolic blood pressure (weighted mean difference [WMD] -2.76 mmHg, 95% confidence interval (CI) -5.71 to 0.18; p=0.07), diastolic blood pressure, (WMD -1.18 mmHg, 95% CI -2.69 to 0.32; p=0.12), or serum creatinine (WMD -7.26 mmol/L, 95% CI -14.99 to 0.47; p=0.07) in the patients who underwent percutaneous intervention compared to the medical therapy group. All but one trial showed at least a moderate overall bias risk.

CONCLUSIONS

We did not find a significant improvement in blood pressure or renal function in patients with renal artery stenosis treated with renal artery revascularisation compared to medical therapy alone. However, trial quality was a limitation.

Management of hypertension in the elderly

Hypertension is the most-prevalent modifiable risk factor for cardiovascular morbidity and mortality worldwide. Hypertension is highly prevalent among older adults (≥65 years), and aging of the population will substantially increase the prevalence of this condition. Age-related endothelial dysfunction and increased arterial stiffness contribute to the increased prevalence of hypertension, particularly systolic hypertension, among the elderly. The incidence of some forms of secondary hypertension also increases with age, mainly owing to the use of drugs (especially NSAIDs that have pressor effects) and the presence of chronic kidney disease, obstructive sleep apnea, and renal artery stenosis. Guidelines differ in thresholds and goals for antihypertensive drug therapy in the elderly because of a paucity of high-level evidence from randomized controlled trials and inconsistencies in the definition of 'elderly'. Medical treatment of hypertension reduces cardiovascular morbidity and mortality in the elderly, and all guidelines recommend lifestyle modifications and medical treatment for elderly patients whose blood pressure exceeds prescribed thresholds and who are at moderate or high cardiovascular disease risk. In the absence of comorbidities, which constitute 'compelling indications' for the use of specific antihypertensive drugs or drug classes, no clear evidence exists to support recommendations for the use of particular antihypertensive-drug classes in older adults.

Renal artery stenosis and its predictors in hypertensive patients undergoing coronary artery angiography

Background

Renal artery stenosis (RAS) has been increasingly recognized in the recent years, especially in patients with coronary artery disease (CAD). RAS affects the patients with hypertension (HTN), but the exact prevalence is not known.

Objectives

This study was performed to determine the prevalence and to identify the predictors of RAS in hypertensive patients undergoing coronary artery angiography.

Patients and Methods

In a cross-sectional study from August 2008 to August 2009, 481 patients with HTN and suspected CAD underwent selective coronary and renal angiography for screening and predicting RAS. RAS was defined as a higher than 50% stenosis in the renal artery lumen. Multivariate analysis of factors associated with the presence of RAS were examined using a logistic regression model.

Results

The mean ± standard deviation of age was 59.25 ± 10.81 years and 50.3% were men. According to angiographic data, 425 patients (88.4%) had CAD, while 56 (11.6%) had normal coronary arteries. RAS was seen in 94 (22%) patients with CAD. The multivariate logistic regression analysis identified only age (P < 0.001) and the number of significant coronary lesions (P < 0.001) as independent predictors of RAS. Gender, smoking, congestive heart failure, diabetes mellitus (DM), hyperlipidemia (HLP) and body mass index (BMI) were not independent predictors.

Conclusions

This study suggests that in the management of patients with RAS, risk factors should most likely be considered as beneficial. In addition, the clinical and angiographic features are helpful in predicting its presence in elderly patients with CAD.

Histomorphometric and sympathetic innervation of the human renal artery: A cadaveric study

Background and Aim:

Renal artery stenosis (RAS) and acute renal failure may be due to the intimal hyperplasia and sympathetic fibers of the renal artery (RA), respectively. The purpose of this study was to characterize arterial wall and sympathetic innervation of the human RA.

Materials and Methods:

Fifty-two fresh human RA samples (proximal part) were collected from 26 cadavers (19 males and 7 females), between the ages of 19 and 83 years, during autopsy. Samples were divided into three age groups: Group 1, 19-40 years; Group 2, 41-60 years; Group 3, over 61 years. 5-μm thick sections of each sample were taken and stained with hematoxylin-eosin and Verhoeff-Van Gieson. Five out of 52 samples were processed for tyrosine hydroxylase (TH) immunostaining.

Results:

Our histological studies revealed that tunica media of RA showed smooth muscle cells and fine irregularly arranged elastic fibers. Intimal hyperplasia was the most common finding. The present study showed that thickness of tunica intima and media were found to increase with age. Sympathetic nerves were present in the tunica adventitia and outer media of the RA. The mean adventitial and sympathetic nerve fiber areas were found to be 0.595 and 0.071 mm², respectively. Sympathetic index (SI) to RA was calculated by dividing the sympathetic fiber area by the adventitial area of the RA. SI of RA was found to be 0.140.

Conclusion:

We conclude that RA showed the structure of musculo-elastic artery. SI may be used for the analysis of sympathetic fiber related problems of the human RA or kidneys.

MR in hypertension

Hypertension is a common systemic disorder affecting the cardiovascular system and kidneys with important morbidity and mortality. However, hypertension is often thought of by radiologists as an "invisible" disease. The aim of this article is to first review hypertension first in terms of its diagnosis, epidemiology and clinical importance. Second, those causes of secondary hypertension that may be diagnosed with MRI techniques are described along with the effects of hypertension on the cardiovascular system and kidneys that are demonstrable with MRI with particular emphasis on renovascular disease. Lastly the use of integrated MRI protocols to evaluate the hypertensive patient and areas for future research are considered.

Atherosclerotic renal artery stenosis: review of pathophysiology, clinical trial evidence, and management strategies

Renal artery stenosis is prevalent and commonly encountered by cardiovascular specialists. Recently published randomized studies have provoked tremendous controversies in the treatment strategy with regard to renal artery stenting. However, these studies are inconclusive because of major study limitations. As such, cardiovascular specialists are uncertain of the indications or utility of renal revascularization, with differing opinions on management by nephrologists and cardiologists. A greater understanding of this disease process, especially with regard to its functional significance and consequence and treatment strategies based on well-designed clinical trials, is sorely needed. Our review focuses on atherosclerotic renal artery stenosis, with an emphasis on indications for revascularization and review of current trial data.

Magnetic resonance angiography and Doppler scanning for detecting atherosclerotic renal artery stenosis

BACKGROUND

Atherosclerotic renal artery stenosis (ARAS) is a progressive but potentially reversible chronic kidney disease. Although the high sensitivity and specificity of renal Doppler scanning (RDS) for ARAS has been reported in western countries, ARAS has not been detected by RDS. This study used magnetic resonance angiography (MRA) to evaluate the sensitivity and specificity of RDS for detecting ARAS among outpatients at a nephrology clinic, and to calculate the degree of underestimation of ARAS by RDS.

METHODS

A total of 257 outpatients, aged > 50 years were examined for ARAS by RDS and MRA.

RESULTS

Thirty-seven (14.4%) and 139 (54.1%) of 257 patients had stenosis detected by RDS and MRA, respectively. Among the 220 patients whose RDS results were negative, MRA detected stenosis in 111 (50.45%). Multivariate logistic regression analysis showed that age > 65 years, duration of smoking, coronary artery disease, and serum creatinine levels > 354 mmol/L (4 mg/dL) were significant and independent factors that influenced ARAS in patients with negative results by RDS.

CONCLUSION

RDS might still be the diagnostic procedure of choice for screening outpatients for ARAS because it is inexpensive, convenient, able to detect severity, and avoids the use of contrast media. When RDS is negative in aged people who have smoked longer than 20 years, with coronary artery disease or serum creatinine > 4 mg/dL, MRA is recommended for further evaluation of ARAS.

Management of renal artery stenosis: the case for intervention, defending current guidelines, and screening (drive-by) renal angiography at the time of catheterization

There is little debate that an untreated significant obstruction of blood flow to the kidney, most often due to atherosclerosis, is potentially hazardous to the health of patients. The treatment of atherosclerotic renovascular disease has evolved over the past 20 years from open surgery with its inherent morbidity and risk of mortality to percutaneous endovascular treatment with stents. The current debate is on the question of which patients are offered any additional advantage by revascularization for renal artery stenosis over medications alone. The primary issue is patient selection, including the most appropriate screening strategies for renal artery stenosis, which must be balanced against the risk of procedure-related complications. The goal of this paper is to explore the most appropriate utilization of revascularization with renal stent placement.

Epidemiology and natural history of atherosclerotic renovascular disease

Atheromatous renovascular disease (ARVD) is increasingly suspected and diagnosed, and it commonly presents to several different clinical specialties. In this review, the epidemiology, risk factors, comorbid disease associations, natural history, and prognosis of ARVD is described. Atheromatous renovascular disease is strongly associated with macrovascular pathology in other important vascular beds, especially the coronary, aortoiliac and iliofemoral circulations, and also with structural and functional heart disease. These clinicopathologic relationships contribute to the high morbidity and mortality associated with the condition. Understanding of the natural history of renal artery stenosis may enable intensified treatment strategies to reduce associated risk and improve patient prognosis.

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.

[Atherosclerotic renal artery disease diagnosis update]

Atherosclerotic renal artery disease represents a cause of which little is known but not a cause to be neglected for hypertension and renal insufficiency. Even though its occurrence remains badly defined, atherosclerotic renal artery disease is constantly on the rise due to the aging population, the never prevailing hypertension and diabetes mellitus. This review aims to give a clinical profile of patients presenting with atherosclerotic renal artery disease and to discuss, in the light of study results, which diagnostic evaluation should be used considering the sequence and the benefit and risk of each in order to initiate a personalized treatment. Patients affected by atherosclerotic renal artery disease are likely to have more complications and more extensive target-organ damage than patients without renal artery stenosis. The evolution of the atherosclerotic renal artery disease is in general slow and progressive. Nevertheless, certain clinical cases manifest themselves with the onset of acute renal failure bought upon by the administration of blockers of the rennin-angiotensin-aldosterone system, or by some other causes responsible for a sudden drop in renal plasma flow (e.g., thrombosis of the renal artery). The relationship between atherosclerotic renal artery disease and atherosclerosis is complex, and mediators implicated in the pathophysiology of renovascular disease may also contribute to the progression of cardiovascular damage. An early assumption of the atherosclerotic renal artery stenosis is warranted to determine the adapted treatment (i.e., medical treatment, revascularisation...) just as the assumption and the correction of the more general cardiovascular risk factors.

Management of acute renal failure in the elderly patient: a clinician's guide

Numerous anatomical and functional changes occurring in the aging kidney lead to reduced glomerular filtration rate, lower renal blood flow and impaired renal autoregulation. The elderly are especially vulnerable to the development of renal dysfunction and in this population acute renal failure (ARF) is a common problem. ARF is often iatrogenic and multifactorial; common iatrogenic combinations include pre-existing renal dysfunction and exposure to nephrotoxins such as radiocontrast agents or aminoglycosides, use of NSAIDs in patients with congestive cardiac failure and use of ACE inhibitors and diuretics in patients with underlying atherosclerotic renal artery stenosis. The aetiology of ARF is classically grouped into three categories: prerenal, intrinsic and postrenal. Prerenal ARF is the second most common cause of ARF in the elderly, accounting for nearly one-third of all hospitalized cases. Common causes can be grouped into true volume depletion (e.g. decreased fluid intake), decreased effective blood volume (e.g. systemic vasodilation) and haemodynamic (e.g. renal artery stenosis, NSAID use). Acute tubular necrosis (ATN) is the most common cause of intrinsic ARF and is responsible for over 50% of ARF in hospitalized patients, and up to 76% of cases in patients in intensive care units. ATN usually occurs after an acute ischaemic or toxic event. The pathogenesis of ATN involves an interplay of processes that include endothelial injury, microvascular flow disruption, tubular hypoxia, dysfunction and apoptosis, tubular obstruction and trans-tubular back-leak. Vasculitis causing ARF should not be missed as this condition is potentially life threatening. The likelihood of a postrenal cause for ARF increases with age. Benign prostatic hypertrophy, prostatic carcinoma and pelvic malignancies are all important causes. Early identification of ARF secondary to obstruction with renal imaging is essential, and complete or partial renal recovery usually ensues following relief of the obstruction.A comprehensive medical and drug history and physical examination are all invaluable. Particular attention should be paid to the fluid status of the patient (skin turgor, jugular venous pressure, lying and standing blood pressure, urine output). Urinalysis should be performed to detect evidence of proteinuria and haematuria, which will aid diagnosis. Fractional excretion of sodium and urine osmolality may be measured but the widespread use of diuretics in the elderly gives rise to unreliable results. Renal imaging, usually ultrasound scanning, is routinely performed for assessment of renal size and to exclude urinary obstruction. In some cases, renal biopsy is necessary to provide specific diagnostic information. The general principles of managing ARF include treatment of life-threatening features such as shock, respiratory failure, hyperkalaemia, pulmonary oedema, metabolic acidosis and sepsis; stopping and avoiding administration of nephrotoxins; optimization of haemodynamic and fluid status; adjustment of drug dosage appropriate to glomerular filtration rate; early nutritional support; and early referral to nephrologists for diagnosis of ARF cause, timely initiation of dialysis and initiation of specific treatment. The treatment of prerenal and ATN ARF is largely supportive with little evidence of benefit from current pharmacological therapies. Despite advances in critical care medicine and renal replacement therapy, the mortality of ARF has not changed significantly over the last 40 years, with current mortality rates being up to 75%.

Renal artery stenosis and chronic ischemic nephropathy: epidemiology and diagnosis

Atherosclerotic renal artery stenosis (RAS) is the most common primary disease of the renal arteries and results in renovascular hypertension and ischemic nephropathy. Ischemic nephropathy from atherosclerotic RAS is increasingly recognized as a cause of chronic kidney disease (CKD) and in severe cases can lead to end-stage renal disease. The exact prevalence of atherosclerotic RAS is unknown because the disease is often asymptomatic and few are screened unless they have significant traditional cardiac risk factors or symptoms. A high prevalence of atherosclerotic RAS is seen in patients with advanced age, congestive heart failure, and extrarenal atherosclerosis. The primary reason for diagnosing ischemic nephropathy from renovascular disease is that the loss of kidney function is potentially reversible through treatment of the occlusion with surgical revascularization or percutaneous transluminal renal angioplasty. However, the benefits of revascularization have to be considered in the context of other comorbid disease and remain controversial. There are several tests available for the screening and diagnosis of atherosclerotic RAS; however, the diagnostic test of choice should be based on patient factors and institutional expertise because the best test is the one performed most often at the individual medical facility.

Navigator-Gated MR Angiography of the Renal Arteries: A Potential Screening Tool for Renal Artery Stenosis

OBJECTIVE

The purpose of our study was to determine how well unenhanced navigator-gated steady-state free precession (Nav SSFP) MR angiography (MRA) performs as a screening test for the detection of renal artery stenosis.

SUBJECTS AND METHODS

Forty patients referred to rule out renal artery stenosis were imaged using an optimized Nav SSFP MRA sequence before conventional contrast-enhanced MRA (CE-MRA). Two radiologists evaluated Nav SSFP for maximum stenosis measurement, and comparison was made with CE-MRA results.

RESULTS

Fifteen of the 40 patients had greater than 50% renal artery stenosis as determined on CE-MRA. Sensitivity for detecting renal artery stenosis with Nav SSFP was 100%; specificity, 84%; negative predictive value, 100%; and positive predictive value, 79%. The average mean stenosis difference between Nav SSFP and CE-MRA was 10% +/- 9%.

CONCLUSION

Sensitivity and negative predictive value for the detection of renal artery stenosis using Nav SSFP were perfect, with an acceptable specificity of 84%. This suggests Nav SSFP is a promising technique for simple unenhanced screening for the detection of renal artery stenosis.

Steady-state free precession MRA of the renal arteries: Breath-hold and navigator-gated techniques vs. CE-MRA

PURPOSE

To explore the use of breath-hold and navigator-gated noncontrast Steady State Free Precession (SSFP) MR angiography (MRA) protocols for the evaluation of renal artery stenosis (RAS).

MATERIALS AND METHODS

Twenty patients referred to rule out RAS were imaged using two breath-hold and one navigator-gated SSFP MRA sequences. All patients underwent contrast-enhanced MRA (CE-MRA). Two radiologists evaluated all sequences both qualitatively (blur, artifacts, reader confidence) and quantitatively (maximum stenosis). Using CE-MRA as truth, a receiver operating characteristics (ROC) curve was generated and a statistical analysis of navigator-gated SSFP (Nav SSFP) was performed.

RESULTS

Seven patients had >50% renal artery stenosis by CE-MRA. Nav SSFP performed significantly better than either breath-hold SSFP technique in terms of blur, artifacts, and reader confidence. Using a 50% threshold for stenosis, sensitivity for detecting RAS was 100%, with a specificity of 85% and a negative predictive value of 100%. The average mean stenosis difference between Nav SSFP and CE-MRA was 9 +/- 9%.

CONCLUSION

Nav SSFP outperformed breath-hold SSFP in measures of image quality and reader confidence. Sensitivity and negative predictive value for detecting RAS with Nav SSFP was perfect, with an acceptable specificity of 85%. This suggests further study is warranted to evaluate Nav SSFP as a noncontrast screening technique for renal artery stenosis.

Quantitative Vascular Measurements in Arterial Occlusive Disease

Accuracy in quantifying arterial occlusive disease requires an understanding of the relevant technical considerations and familiarity with the strengths and weaknesses of various imaging modalities in this setting. The degree of stenosis is evaluated in terms of diameter stenosis, which can be measured on either projection images or cross-sectional images, or area stenosis, which can be measured only on cross-sectional images. With projection images, the minimum luminal diameter should be sought on multiple images obtained at different angles. The reference site used for measurement should be noted and may be located at the level of the lesion or in a normal-looking portion of the stenotic vessel near the lesion. Multi-detector row computed tomographic (CT) angiography and magnetic resonance (MR) angiography are starting to replace digital subtraction angiography in quantifying arterial occlusive disease. CT angiography allows accurate evaluation without reducing in-plane resolution, although beam-hardening artifacts from high-attenuation structures can degrade image quality. MR angiography is useful even in cases of severe calcification but has a lower spatial resolution. Ultrasonography (US) may also be helpful in quantifying arterial occlusive disease; US analysis is almost always based on blood flow velocity measurement. Precise measurements of stenotic occlusion will help determine optimal therapy for affected patients.

Atherosclerotic renovascular disease in chronic heart failure: should we intervene?

Renal artery stenosis (RAS) is most commonly caused by atherosclerosis, which is also the most common cause of chronic heart failure (CHF). One-third of patients with CHF are reported to have significant renovascular disease. The presence of RAS confers a worse outcome in studies of hypertension and coronary disease, though data are lacking for patients with CHF. As the kidney is intricately involved in the fluid retention that occurs in CHF, an adverse effect of RAS on outcome would be expected. Presentations of RAS in CHF include flash pulmonary oedema, hypertension, worsening of CHF, and worsening renal function. RAS commonly progresses and may cause worsening of renal function in patients with CHF and previously stable renal function. A variety of investigations that can safely and accurately identify RAS in CHF are available, although none is recommended in current guidelines for the management of CHF. Treatment for RAS, whether for hypertension, for renal dysfunction, or for pulmonary oedema, is at the discretion of the physician due to the lack of adequate randomized controlled trials demonstrating the efficacy and safety of intervention. As it is not clear how RAS should be managed in CHF, screening cannot be advocated. Currently, a multicentre randomized outcome trial, which includes a cohort of patients with RAS and CHF, is in progress to provide answers in this area of uncertainty.

Dilemmas in the management of renal artery stenosis

Atherosclerotic renovascular disease (ARVD) accounts for >90% of renal artery stenosis (RAS) in Western populations; the remainder are due to fibromuscular disease (FMD). The epidemiology is quite different in the Indian subcontinent and the Far East where Takayasu's arteritis may be responsible for up to 60% of RAS cases. ARVD is very commonly associated with hypertension and renal dysfunction; it is a disease of ageing and is frequently observed in association with other vascular diseases. There is increasing evidence that in patients with ARVD and chronic renal dysfunction the aetiology of the latter is more often due to long-standing intra-renal vascular disease and parenchymal injury than to reversible ischaemia. This is reflected in the variability in renal functional outcome following revascularization, with an improvement in renal function being observed in only a minority of patients; the majority show no apparent change or even a decline in renal function. A major current challenge concerns the identification of patients who are likely to benefit from renal revascularization procedures, but technological advances in imaging offer potential in aiding this selection. Large-scale randomized controlled trials are required to determine the overall effects of renal artery intervention and, more specifically, to help identify which subgroups of patients will benefit from revascularization.

Ultrasound measured renal length versus low dose CT volume in predicting single kidney glomerular filtration rate

Ultrasound measured renal length and CT measured renal volume are potential surrogate markers for single kidney glomerular filtration rate (SKGFR). The aims of this study are to determine: (1) the repeatability of ultrasound measured length and low radiation dose spiral CT measured volume; (2) the relationship between renal length and volume; and (3) whether length and/or volume is a predictor of SKGFR. 69 patients with suspected renal artery stenosis underwent ultrasound renal length measurement, CT evaluation of renal volume and assessment of SKGFR. 40 patients had ultrasound measurement of length and CT evaluation of volume performed twice on two separate visits. 25 patients also had ultrasound measured renal parenchymal thickness and area. The region of interest was drawn around the kidneys and a threshold set to subtract renal peripelvic fat and renal pelvis. The volume from each slice was summed to obtain the total volume for each kidney. The limits of agreement for ultrasound measured renal length were -1.6 cm to 1.52 cm and that for CT renal volume were -33 ml to 32 ml. There was significant correlation between ultrasound measured length and CT volume (r=0.74, p<0.01). Volume was a better predictor of SKGFR (r(2)=0.57) than length (r(2)=0.48). The combined parameters of ultrasound measured length, area and parenchymal thickness were a better predictor of volume (r(2)=0.81) and SKGFR (r(2)=0.58) than ultrasound measured length on its own. The low dose CT technique was reasonably reproducible and renal volume measurements correlate better with SKGFR than length. Ultrasound predictions of renal volume and SKGFR can be improved by incorporating cross-sectional area and parenchymal thickness. Further investigation is required to refine our low dose CT technique.

Associations between renovascular disease and prevalent cardiovascular disease in the elderly: a population-based study

Atherosclerotic renovascular disease (RVD) is a suspected contributor to the morbidity and mortality of cardiovascular disease (CVD) through its potential effects on blood pressure and excretory renal function as well as through its associations with other forms of CVD. However, population-based data regarding the associations between the presence of RVD and prevalent CVD are lacking. The Cardiovascular Health Study (CHS) is a prospective, multicenter cohort study of CVD among elderly Americans. As part of an ancillary study, participants in the Forsyth County, North Carolina, cohort of the CHS were invited to undergo renal duplex sonography (RDS) to establish the presence or absence of RVD (defined as any focal peak systolic velocity >/= 1.8 m/second or the absence of a Doppler-shifted signal from an imaged artery). Demographic, risk factor, and prevalent CVD data were obtained from the CHS coordinating center and matched with ancillary study participants. Eight hundred thirty-four CHS participants (including 525 women [63%], 309 men [37%], 194 African-Americans [23%], and 635 Caucasians [76%]) with a mean age of 77.2 +/-4.9 years underwent RDS examination. RVD was present in 57 participants (6.8%). Overall, clinical and/or subclinical manifestations of CVD were present in 603 participants (72.3%) at the time of RDS. Participants with RVD demonstrated a significantly greater prevalence of angina (p = 0.002), previous myocardial infarction (p < 0.001), >/= 25% diameter-reducing internal carotid artery stenosis (p = 0.010), increased carotid intimal medial thickness (p = 0.003), and major electrocardiographic abnormalities (p = 0.013). Following adjustment for demographics and cardiovascular risk factors, the presence of RVD demonstrated a significant and independent association with prevalent coronary artery disease but not with prevalent cerebrovascular or lower extremity vascular disease. These results suggest important population-based associations between RVD and both clinical and subclinical manifestations of CVD, especially coronary artery disease.

Renal angioplasty and stenting with distal protection of the main renal artery in ischemic nephropathy: early experience

PURPOSE

We present a retrospective review of a single tertiary hospital experience in renal artery stent revascularization with distal protection in patients with ischemic nephropathy. The objectives of the study included preliminary assessment of the effect of distal protection on procedure-related acute deterioration in renal function and on renal salvage.

MATERIAL AND METHODS

All patients had significant atherosclerotic main renal artery stenosis, documented at preprocedural imaging, and a degree of chronic renal impairment before revascularization. Forty-six renal arteries were treated in 37 patients with preprocedural renal impairment, which was mild in 10 patients, moderate in 19 patients, and severe in 8 patients. Median patient age was 72 years (range, 59-85 years). All patients underwent primary stenting of renal artery ostial stenoses with adjuvant use of a filter device (Angioguard guide wire system; Cordis Corp, Division of Johnson & Johnson, Miami, Fla) in the distal main renal artery. The filter baskets were recaptured for pathologic analysis.

RESULTS

Overall, in 95% of patients, including all patients with preprocedural mild or moderate renal impairment, renal function was stabilized or improved after revascularization. In 5% of patients decline in renal function was unchanged. No patients had acute postprocedural deterioration. Mean follow-up was 12.5 months (range, 2-28 months). These results are better than in most reports in the literature and also better than in a historical group of similar patients with ischemic nephropathy who underwent stent revascularization without distal protection at the same institution. The improved results are thought to be due to prevention of cholesterol atheroembolization during the procedure by the distal filter baskets. Sixty-five percent of the distal protection baskets contained embolic material, including fresh thrombus, chronic thrombus, atheromatous fragments, and cholesterol clefts.

CONCLUSION

A distal protection device may significantly improve results during stent revascularization. There are a number of unique demands on a renal protection device, and the ideal device has not yet been developed.

Percutaneous stenting of incidental unilateral renal artery stenosis: decision analysis of costs and benefits

PURPOSE

To determine the incremental cost-effectiveness of prophylactic percutaneous transluminal angioplasty with stent placement (PTA-S) in patients with incidentally discovered, asymptomatic renal artery stenosis (RAS) compared to delaying PTA-S until patients develop refractory hypertension or renal insufficiency (therapeutic PTA-S).

METHODS

The Markov decision analysis model was used to determine the incremental cost per quality adjusted life year (QALY) saved for prophylactic PTA-S as compared to therapeutic PTA-S in a hypothetical cohort of patients with 50% unilateral atherosclerotic RAS followed from age 61 to death.

RESULTS

Prophylactic PTA-S compared to therapeutic PTA-S results in more QALYs/patient (10.9 versus 10.3) at higher lifetime costs ($23,664 versus $16,558). The incremental cost effectiveness of prophylactic PTA-S was estimated to be $12,466/QALY. Prophylactic stenting was not cost effective (>$50,000/QALY) if the modeled incidence of stent restenosis exceeded 15%/year and the incidence of progression in the contralateral renal artery was <2% of arteries/year.

CONCLUSIONS

PTA-S of incidental, asymptomatic unilateral RAS may improve patients' quality of life at an acceptable incremental cost. However, this technology should be used hesitantly until a randomized comparison confirms its effectiveness.

Prevalence of renal artery stenosis in high-risk veterans referred to cardiac catheterization

OBJECTIVE

The prevalence of atherosclerotic renal artery stenosis (RAS) varies depending on patient selection with no specific guidelines on indications for selective renal angiography in patients referred for coronary angiography. The goal of this study is to determine the prevalence and predictors of renal artery stenosis in hypertensive veterans referred for coronary angiography.

DESIGN

Prospective study.

SETTING

Tertiary care veterans' administration facility in the USA.

PATIENTS, PARTICIPANTS

A total of 90 veterans referred for coronary angiography with an initial ascending aortic pressure > 135 mmHg.

INTERVENTIONS

Selective renal angiography was performed following coronary angiography.

RESULTS

We found that 28% of the patients had single RAS (> or = 50% stenosis), while 16% had single RAS > or = 70% stenosis, 10% had bilateral RAS >or = 50% and 6% had bilateral RAS > or = 70%. Significant positive univariate predictors of RAS (> or = 50%) were age, peripheral vascular disease (PVD), creatinine level (Cr) and myocardial infarction. Significant multivariate predictors of RAS (> or = 50%) were age > 65 years [relative risk (RR), 3.6; 95% confidence interval (CI), (1.2-10.6)], PVD [RR 3.2, 95% CI (1.1-9.1)] and Cr > 1 mg/dl [RR 4.9, 95% CI (1.53-15.9)]. No complications related to renal angiography were noted.

CONCLUSIONS

Selective renal angiography during routine coronary angiography in hypertensive veterans with coronary artery disease is safe and uncovers RAS in many older patients with PVD and renal insufficiency.

Relationships between renovascular disease, blood pressure, and renal function in the elderly: a population-based study

BACKGROUND

The purpose of this study is to examine the associations between renovascular disease (RVD) and cross-sectional measures of blood pressure and renal function among participants in the Cardiovascular Health Study (CHS).

METHODS

The CHS is a prospective cohort study of cardiovascular disease among elderly Americans. As part of an ancillary study, participants in the Forsyth County, NC, cohort of the CHS were invited to undergo renal duplex sonography (RDS) to define the presence or absence of RVD (defined as any focal peak systolic velocity > or = 1.8 milliseconds or the absence of a Doppler shifted signal from an imaged artery). Demographic, risk factor, blood pressure, and serum creatinine data were obtained at the time of RDS and from the annual CHS examination.

RESULTS

Eight hundred thirty-four CHS participants (including 525 women [63%], 309 men [37%], 194 African Americans [23%], and 635 Caucasians [76%]) with a mean age of 77.2 +/- 4.9 years underwent successful RDS. RVD was present in 57 participants (6.8%). When examined according to the presence or absence of RVD, significant univariate differences were observed in the prevalence of clinical hypertension (72% versus 50%; P = 0.001), systolic blood pressure (145 versus 136 mm Hg; P = 0.001), and renal insufficiency (16% versus 8%; P = 0.041). Multivariate analyses showed significant and independent associations for the presence of RVD with increasing systolic blood pressure (P = 0.034), clinical hypertension (odds ratio, 2.68; 95% confidence interval, 1.44 to 4.99; P = 0.002), increasing serum creatinine level, and renal insufficiency (odds ratio, 2.21; 95% confidence interval, 1.02 to 4.79; P = 0.043). A significant interaction was observed between the presence of RVD and increasing systolic blood pressure in association with increasing serum creatinine levels (P = 0.041).

CONCLUSION

These results suggest important population-based associations between RVD and cross-sectional measures of blood pressure and renal function. Furthermore, the observed relationship between RVD and increasing serum creatinine level was influenced strongly by increasing blood pressure.

The impact of atherosclerotic renovascular disease on diabetic renal failure

Atherosclerotic renovascular disease (ARVD) is common in the general population, and its prevalence increases with age. Parallel studies show it is also common in patients with diabetes. The widespread use of angiotensin converting enzyme inhibitors and angiotensin receptor antagonists for heart and kidney disease might therefore expose arteriopathic diabetic patients to potential harm if they had critical renal artery stenosis. This review looks at the natural history of ARVD in the diabetic and non-diabetic populations: while it is common, it only rarely leads to renal failure. Hence intervention to revascularize ischaemic kidney son the basis of radiological appearances alone may subject some patients to unnecessary therapy. Although untested by randomized trial, a policy of watchful waiting may be the simplest strategy for most diabetic patients with suspected ARVD, reserving angiography and angioplasty (usually backed up by a stent) for those with an abrupt decline in renal function and no other cause for renal deterioration. Future clinical trials may better define subgroups of patients who will truly benefit from renal revascularization.

Atherosclerotic renal artery stenosis: epidemiology, cardiovascular outcomes, and clinical prediction rules

Atherosclerotic renal artery stenosis is the most common primary disease of the renal arteries, and it is associated with two major clinical syndromes, ischemic renal disease and hypertension. The prevalence of this disease in the population is undefined because there is no simple and reliable test that can be applied on a large scale. Renal artery involvement in patients with coronary heart disease and/or heart failure is frequent, and it may influence cardiovascular outcomes and survival in these patients. Suspecting renal arterial stenosis in patients with recurrent episodes of pulmonary edema is justified by observations showing that about one third of elderly patients with heart failure display atherosclerotic renal disease. Whether interventions aimed at restoring arterial patency may reduce the high mortality in patients with heart failure is still unclear because, to date, no prospective study has been carried out in these patients. Increased awareness of the need for cost containment has renewed the interest in clinical cues for suspecting renovascular hypertension. In this regard, the DRASTIC study constitutes an important attempt at validating clinical prediction rules. In this study, a clinical rule was derived that predicted renal artery stenosis as efficiently as renal scintigraphy (sensitivity: clinical rule, 65% versus scintigraphy, 72%; specificity: 87% versus 92%). When tested in a systematic and quantitative manner, clinical findings can perform as accurately as more complex tests in the detection of renal artery stenosis.

A prospective study of the determinants of renal functional outcome and mortality in atherosclerotic renovascular disease

Atherosclerotic renovascular disease (ARVD) commonly causes renal failure and hypertension and is accompanied by high cardiovascular comorbidity and mortality. Interrelationships between these factors remain poorly understood. Patients with ARVD presenting to a single center between 1995 and 1999 were followed up, with prospective collection of clinical and biochemical data. Fifty men and 48 women were identified. Mean age at entry was 68.7 +/- 8.3 (SD) years, and baseline creatinine clearance (CrCl) was 35.5 +/- 20.7 mL/min. During follow-up (27.7 +/- 18.7 months), 10 patients required dialysis therapy, 11 patients underwent revascularization, and 35 patients (36%) died. Patients in whom renal function deteriorated during follow-up (n = 61) had similar ages, baseline CrCls, blood pressures, and comorbidities compared to patients with stable function. Mortality (55.7% versus 27.0%; P < 0.01) and proteinuria (protein, 1.3 +/- 1.6 versus 0.3 +/- 0.4 g/24 h; P < 0.001) were greater in patients with declining function. Baseline renal function was not significantly related to blood pressure, proteinuria, or change in renal function during follow-up (change in CrCl), but patients with a lower CrCl had increased mortality. There was no increase in cardiovascular comorbidity in groups with lower renal function. Patients with the most severe anatomic ARVD had worse hypertension and increased mortality, but severity of ARVD was unrelated to extent of renal dysfunction and proteinuria at baseline. Lack of correlation between renal artery anatomy and baseline renal function or functional outcome and correlation between renal functional outcome and proteinuria suggest that renal parenchymal damage is a major determinant of renal dysfunction and outcome in ARVD.

Ischemic renal disease in Kuwait

Ischemic renal disease (IRD) is a frequent cause of end-stage renal disease. Its prevalence is mainly known from autopsy or retrospective arteriographic studies. This prospective study was conducted in 115 subjects selected from 732 patients with advanced chronic renal failure (CRF). Only patients with clinical features suggestive of IRD were selected for this study. In addition to detailed clinical and laboratory evaluation, captopril renal scintigraphy was performed in selected cases. All subjects underwent renal arteriography and all were followed up for 18.4 +/- 11.4 months. Renovascular disease was seen in 15 patients and significant bilateral renal artery disease leading to IRD was observed in 13 (11.3%). Hence the prevalence of IRD in the advanced CRF patients was 1.7%. The majority of patients with IRD (8 [61%]) were above 46 years of age and there were more men than women (10:3). Atherosclerotic renovascular disease was the most common (10 [77%]), even though arthritis (1 [7.6%]), and fibromuscular dysplasia (2 [15.3%]) were also observed. Serum creatinine at time of presentation was significantly higher in patients with IRD (784 +/- 292, p = 0.043) compared to those who did not have IRD (359 +/- 126). Corrective procedures were performed in 5 patients. After treatment the improvement in serum creatinine in patients with IRD at 3 and 6 months (166 +/- 32 and 173 +/- 47, respectively) was significantly different (p < or = 0.05) compared to those who were not treated (610 +/- 194 and 645 +/- 220, respectively). Hyperlipidemia, coronary artery disease and peripheral vascular disease were more prevalent in patients who had IRD compared to those with renal failure. The incidence of diabetes mellitus were similar in both groups. This study denotes a lower prevalence of IRD in the advanced CRF population; they had more severe renal failure at presentation but specific corrective treatment delayed progression of renal disease significantly.

The natural history of incidental renal artery stenosis in patients with aortoiliac vascular disease

PURPOSE

To examine the association between incidentally discovered renal artery stenosis and deterioration of renal function as determined by the change in serum creatinine concentration over time.

SUBJECTS AND METHODS

We performed a retrospective review of consecutive patients who underwent aortography for aortoiliac vascular disease. Angiograms were reviewed for renal artery stenosis, defined as a narrowing of at least 20% compared with adjacent normal renal artery. For patients with at least 180 days of subsequent follow-up, the change in serum creatinine concentration per year was compared in patients who had or did not have renal artery stenosis.

RESULTS

Of the 201 patients, 96 (48%) had some degree of renal artery stenosis in one or both renal arteries, including 53 (26%) who had at least one stenosis > or= 50% and 40 (20%) who had bilateral stenoses. The only clinical predictor of renal artery stenosis was a history of coronary artery disease (odds ratio = 2.0, 95% confidence interval: 1.2 to 3.8, P = 0.001). Among the 174 patients with > or =180 days of follow-up, there was no statistically significant difference (P = 0.88) in the mean change in serum creatinine concentration per year in the 78 patients with renal artery stenosis (0.06+/-0.33 mg/dL per year) as compared with the 96 patients without renal artery stenosis (0.06+/-0.22 mg/dL per year). Grouping the patients by the maximal percentage of stenosis did not reveal any difference in the mean changes in serum creatinine concentration per year.

CONCLUSIONS

Although renal artery stenosis is a common incidental finding in patients with atherosclerotic vascular disease, it is an uncommon cause of progressive renal disease.

Ischemic nephropathy: clinical characteristics and treatment

Ischemic nephropathy is a long-term cause of hypertension and renal failure. Although its real incidence is unknown, ischemic nephropathy is growing because of the increased mean age of the population and the greater prevalence of hypertensive and diabetic populations. This review describes the clinical profile of afflicted patients. Atherosclerosis in different vascular beds is common in these patients. The evolution of ischemic nephropathy is generally progressive, although some patients present with acute renal failure, either secondary to the administration of angiotensin-converting enzyme inhibitors or caused by thrombosis of the renal arteries. Revascularizing surgery may stabilize or improve renal function, even in patients with nonfunctioning kidneys. The results obtained with intraluminal angioplasty are worse, with a high percentage of restenosis. Placement of an endoprothesis is recommended when the lesions affect the ostium or proximal third of the artery. This complex disease typically affects multiple organs, thus making individual assessment essential.

New insights into the epidemiologic and clinical manifestations of atherosclerotic renovascular disease

Atherosclerotic renovascular disease (ARVD) continues to challenge the clinician as we enter the third millenium. ARVD frequently complicates patients with other vascular pathological states, and it is an increasingly common cause of end-stage renal failure. Although renovascular interventional procedures are now widely available and are of benefit to some patients with ARVD, a large proportion still progress to dialysis. Recent epidemiological investigations have emphasized the relationship between ARVD and other vascular diseases, and these are notable in patients with coronary artery disease and/or cardiac failure. Increased awareness of the possible coexistence of ARVD in patients with these latter conditions may allow earlier diagnosis and a minimization of complications (eg, angiotensin-converting enzyme inhibitor-related uremia or flash pulmonary edema). Contemporary studies also highlight the importance of intrarenal vascular and parenchymal injury in the cause of chronic renal failure in many patients with ARVD. Severe renal structural damage often coexists with proximal renal arterial narrowing, and this can explain the variability of renal functional outcomes known to accompany revascularization procedures. More appropriate selection of those patients likely to benefit from renovascular revascularization is now required. Large-scale trials that will identify the optimal approach to improving renal functional and survival outcomes in this high-risk group of patients are now long overdue.

Prevalence of renal artery stenosis in autopsy patients with stroke

BACKGROUND AND PURPOSE

Atherosclerotic renal artery stenosis commonly exists as one manifestation of more generalized atherosclerosis. It is a progressive but potentially curable disorder. Thus, information on renal artery involvement in atherosclerotic diseases could be important. We investigated the prevalence of renal artery stenosis in autopsied patients with stroke over 40 years of age.

METHODS

From 2167 consecutive autopsy patients who died between 1980 and 1997, we studied 346 cases of mean age of 69+/-11 years with clinical evidence of stroke.

RESULTS

Atherosclerotic renal artery stenosis (>/=75% luminal area narrowing) was found in 36 patients (10.4%). Patients with renal artery stenosis were older and had worse renal function. Renal artery stenosis was found in 14.7%, 28.6%, and 23.9% of patients with hypertension, renal insufficiency, and aortic aneurysm, respectively. Extracranial carotid artery stenosis (>50% luminal area narrowing) was found in 101 patients (29.2%). Of the 346 stroke patients, 256 had a history of brain infarction. In patients with brain infarction, renal artery stenosis was found in 31 (12.1%) and carotid stenosis was found in 81 (33.6%). Patients with carotid artery stenosis were more likely to have renal artery stenosis than patients without carotid artery stenosis (24.4% versus 5.9%, P<0.0001). Multiple logistic regression analysis identified renal insufficiency, hypertension, female gender, and presence of carotid artery stenosis as independent predictors of renal artery stenosis in patients with brain infarction.

CONCLUSIONS

These data reveal that atherosclerotic renal artery stenosis is common in patients with stroke, especially in those with brain infarction.

Renal angioplasty: better for treating hypertension or for rescuing renal function?

Angioplasty of renal artery stenosis has been used extensively in the last two decades for treating renovascular hypertension, and, more recently, for preserving the jeopardized renal function. A large body of evidence has accumulated indicating that this approach is by far the most convenient for patients with fibromuscular stenosis in whom the technical success of the procedure is followed by a high cure rate (50%) or at least by some improvement of blood pressure (40%). In contrast, in patients with atheromatous stenosis, the rate of cure is very low (8-10% at best) and the rate of improvement is between 40 and 50% irrespective of whether the stenosis is treated with angioplasty or with stent implantation. Thus, before undergoing procedures which are not devoid of potentially serious side-effects, these patients should be thoroughly investigated to select those in whom the benefit actually outweighs the risks. Studies investigating the effects of angioplasty on renal function are less numerous than those addressing the effects on blood pressure, and, in most cases, suffer the limitation of using the levels of serum creatinine as the sole marker of the changes in glomerular filtration rate induced by the procedure. These investigations have shown that some amelioration can be achieved in one-third of patients, with another third having unmodified levels of creatinine at follow-up. Radioisotopic techniques, which allow a more precise and separate evaluation of the function of the two kidneys, appear to be a promising alternative for the investigation of the effects of angioplasty; indeed, preliminary studies which took advantage of these methodologies have shown that the function of the stenotic kidney can possibly be rescued by slowly reversing the multiple mechanisms by which chronic ischaemia damages the kidney.