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.

Screening, diagnosis, and treatment of renal artery stenosis by percutaneous transluminal renal angioplasty with stenting

BACKGROUND

Renal artery stenosis is one of the most frequent causes of secondary hypertension. Appropriate methods for screening, diagnosis and therapy are currently under debate.

OBJECTIVES

To evaluate and recommend methods for screening and diagnosing renal artery stenosis, and to assess the clinical outcomes of renal artery stenting.

METHODS

A total of 450 patients undergoing non-emergent coronary angiography fulfilled the selection criteria for selective renal arteriography; those with severe (luminal narrowing > or = 70%) renal artery stenosis underwent percutaneous transluminal renal angioplasty with renal artery stenting.

RESULTS

Of 166 patients (36.9%) with renal artery stenosis, 41 (9.1%) had severe stenosis that required renal artery stenting, and 83% had ostial renal stenosis. The primary success rate was 100% and there were no complications. During the follow-up period, two patients required a second PTRA. After stent deployment, significant reductions were observed in systolic and diastolic pressures (P < 0.001 and P = 0.01, respectively) and in the number of antihypertensive drugs used by the patients (P < 0.001). These reductions were sustained during follow-up. Hypertension was cured (systolic blood pressure < 130 mmHg) in 9 patients (21.4%) and improved in 27 (64.3%). Plasma creatinine did not change significantly.

CONCLUSIONS

Selective renal angiography is an effective diagnostic tool for identifying symptomatic cases of renal artery stenosis in patients undergoing coronary angiography. Our finding of a high success rate and low complication rate supports the use of primary renal artery stenting in symptomatic patients with renal artery stenosis.

Computer-aided auscultation to diagnose Renal Artery Stenosis

Renal Artery Stenosis (RAS) is the most common cause of secondary hypertension, and early diagnosis is important since correct and timely treatment may cure hypertension and prevent loss of renal function. This study investigates a new approach to diagnosing renal artery stenosis by computer analysis of the phonogram recorded with an electronic stethoscope. Phonograms recorded from five positions over the renal arteries were obtained, three from patients with confirmed RAS and 15 from healthy subjects. Two features describing the power ratios between the systolic and diastolic periods in two different frequency bands were extracted. It was possible to discriminate all three RAS subjects from the healthy subjects in the frequency band 0.4-1.1 kHz. However, the number of subjects is insufficient to draw statistically significant conclusions about the performance of the system.

[Renal artery stenosis in patients with type 2 diabetes mellitus: clinical signs, diagnosis, prognostic value]

AIM

To define the prevalence, clinical features, risk factors, and prognostic value of atherosclerotic renal artery stenosis (RAS) in patients with type 2 diabetes mellitus (T2DM).

SUBJECTS AND METHODS

One hundred and fifty-seven T2DM patients (63 males and 94 females) aged over 50 years were examined. Screening for RAS was carried out by duplex ultrasound scanning (DUSS); the diagnosis was verified by multispiral computed tomography and magnetic resonance imaging. Moreover, the detection rate of RAS was analyzed from the selective angiographic readings of 30 patients with T2DM and 26 coronary angiography patients without DM who had undergone coronary angiography (CA).

RESULTS

In the total group of T2DM patients, the RAS detection rate was 36.9%, as evidenced by DUSS and 43.3% by selective renal artery angiography in the patients who had undergone CA. The factors associated with the development of RAS were smoking (relative risk (RR) = 3.3; p < 0.001); atherosclerosis of coronary (RR = 4.28; p < 0.001) and peripheral (RR = 3.38; p < 0.02) arteries, isolated systolic hypertension (RR = 3.9; p < 0.01), and anemia (RR = 6.4; p < 0.001). In patients with T2DM, RAS was one of the important factors of progressive renal and cardiac diseases and increased mortality determined by the combined end point: death, emergency hospitalization for heart failure, myocardial infarction, double creatinine, and end-stage renal failure (RR = 6.28; p < 0.001).

CONCLUSION

The optimization of prognosis in T2DM patients with RAS requires its timely clinical identification in combination with other types of renal lesion, aggressive correction of the mechanisms of the progressive process, and development of medical and endovascular therapies.

Stenting renal artery stenosis: what is the fuss all about?

Renal artery stenosis is the most common cause of secondary hypertension after exclusion of renal parenchymal disease and/or hypertensive nephrosclerosis. Atherosclerotic processes comprise the major contributors to this condition and account for 90% of the disease burden. Usually, the disease comes to light when there has been substantial morbidity resulting from several years of uncontrolled blood pressures and renal failure. Early recognition and intervention is warranted. Interventions include both medical and surgical modalities. Currently, there are several reliable diagnostic procedures to identify renal artery stenosis. However, once the disease process is identified, the management differs quite dramatically based on the patient population, the goals of therapy such as control of hypertension versus amelioration of ischemic nephropathy, availability of interventionists and so on. In this review, we discuss the importance of identifying atherosclerotic renal artery stenosis, the diagnostic modalities available and some of the interventions used to manage this disorder. We emphasize evidence based medicine and recent clinical trials such as the STAR trial.

Clinical practice. Renal-artery stenosis

A 73-year-old former smoker with a history of hypertension and dyslipidemia presents to the emergency department with shortness of breath. His blood pressure is 160/75 mm Hg, heart rate 60 beats per minute, and respiratory rate 24 breaths per minute. Chest auscultation reveals diffuse rales, and there is 1+ pitting edema. The serum creatinine level is 1.4 mg per deciliter (124 µmol per liter) (estimated glomerular filtration rate, 52 ml per minute), and urinalysis shows 1+ protein. His condition improves after treatment with intravenous diuretics, but his systolic blood pressure remains elevated, at 170 mm Hg. Magnetic resonance angiography (MRA) reveals a diseased aorta, a high-grade ostial lesion of the left renal artery that is consistent with atherosclerotic stenosis, and a normal right renal artery. How should he be further evaluated and treated?

Use of extracorporeal circulation and selective renal perfusion during the surgical correction of abdominal aortic coarctation

Coarctation of the abdominal aorta is a rare pathology. Stenosis of visceral and renal arteries may present together with coarctation, which requires specific operation techniques. We present the case of a patient with coarctation of the abdominal aorta associated with stenosis of the celiac trunk, the superior mesenteric and the right renal arteries. Distal aortic perfusion by extracorporeal circulation and selective right renal perfusion techniques were used during the operation to protect the spinal cord and kidney against hypoperfusion and ischemia.

Renal artery stenosis: diagnostic performance of balanced fast field gradient echo MRA

OBJECTIVE

To compare the diagnostic performance of new B-FFE MR angiography with contrast-enhance MR angiography in diagnosis of renal artery stenosis.

MATERIAL AND METHOD

One hundred and fourteen patients suspected of having renal artery stenosi underwent MR angiography with 2D B-FFE technique and 3D post contrast enhancement.

RESULTS

Compared with contrast enhanced MR angiography, B-FFE MR angiography correctly depicte, significant stenotic renal arteries (> or = 50% stenosis) in 13 and 12 renal arteries from 21 renal arteries reviewed by first and second radiologists, respectively. The overall sensitivity, specificity, negative an, positive predictive values of B-FFE MR angiography in diagnosis of significant renal artery stenosis (> or =50% stenosis) reviewed by first and second radiologists, were 57.1-61.9%, 91.9-93.6%, 96.1-96 4%, and 81.3 92.3%, respectively.

CONCLUSION

B-FFE MR angiography of renal arteries can be promising technique for screening patient. who are suspected of having renovascular disease without requirement of intravenous contrast injection especially the kidney disease patients.

[Renal artery stenosis--diagnosis and treatment]

Screening for renal artery stenosis (RAS) should be restricted to patients with a high RAS risk. Captopril renography, computed tomography (CT)-angiography, magnetic resonance (MR)-angiography and ultrasound (US) Doppler can be used. Most patients should receive medical treatment. If predictive tests suggest a good outcome, revascularisation with percutaneous transluminal renal angioplasty (PTRA) should be considered in patients with refractory hypertension, fibromuscular dysplasia, recurrent pulmonary oedema, bilateral renal artery stenosis or progressive azotaemia, and in patients with a narrow stenosis to a single kidney.

[Renal hypertension. A case report - therapeutic dilemmas]

Hypertension associated with fibromuscular dysplasia of renal artery is the most common form of secondary hypertension among young patients. In this article we present a case of a 27-year-old patient, with drug-resistant hypertension. Stenosis of right renal artery and small right kidney were found on ultrasonography, angio-CT and angiography. There was no sign of renal atrophy therefore we performed percutaneous transluminal angioplasty. After the procedure we observed a decrease in blood pressure and no need to use hypertensive medication. Diagnosis and treatment of this condition are discussed.

Unexpected complete aortorenal occlusion

In chronic aorto-iliac occlusive disease, pre-existing renal artery stenosis may give rise to sufficient development of collateral blood flow and prevent ischaemic symptoms for a long time and therefore may cause delay in diagnosis. An early diagnosis of aorto-iliac disease is necessary in order to avoid fatal outcome. Duplex scanning is generally used to rule out a renal artery stenosis. This can generally detect the occlusion, but has some drawbacks such as obesity gas interposition, accessory renal arteries or the anatomy of the left renal artery, which may hinder complete examination of both renal arteries and may give rise to misdiagnosis. On the other hand, CT may provide detailed anatomic information. In this paper, we present a case of total aortorenal occlusion mimicking renal artery stenosis on duplex scanning.

[Renal artery stenosis after abdominal radiotherapy]

INTRODUCTION

Renal artery stenosis represented 1 to 5% of all arterial hypertensions and is the leading cause of secondary hypertension. Renovascular hypertension is more common among women less than 30 years old (fibrodysplasia, 33%) and men older than 50 years old (66% atherosclerosis). Other causes are rare, especially radiation-induced renal artery stenosis.

MATERIALS AND METHODS

We report the case of Mr. D., 49 years old, with severe high blood pressure (230/125 mmHg) seven years after abdominal radiotherapy for Hodgkin's disease. Echo-Doppler was performed and found a subocclusive right ostial renal artery stenosis probably radiation-induced taking into account the history of the patient. Renal angiography confirmed this diagnosis and percutaneous transluminal renal artery angioplasty was performed with a final acceptable result (residual stenosis<50%).

DISCUSSION

Radiation-induced renal artery stenosis is rare (0.5/1000 to 1%). Most of the cases are proximal and the median time from radiation to referral is nine years. Radiation-induced nephritis disease was often referred to occurrence high blood pressure after abdominal radiotherapy but various data shows that radiation can also cause damage to larger vessels sizes (such as renal arteries) induced by atherosclerosis radiation. Patients should be successful treated by percutaneous intervention, as demonstrated by Fakhouri et al. [Am J Kidney Dis 38 (2001) 302-309] in a study of 11 patients.

CONCLUSION

This case shows that radiation-induced renal artery stenosis may occur many years after initial treatment, and patients developing severe arterial hypertension after abdominal radiation should be investigated for renal artery stenosis.

Renal artery stenosis in hypertensive patients with or without type 2 diabetes: a comparative magnetic resonance angiography study

BACKGROUND

Increased prevalence of various vascular diseases is common in type 2 diabetes mellitus. However, the increased prevalence of renal artery atheroma resulting in renal artery stenosis in patients with diabetes mellitus has not been fully assessed. We used magnetic resonance angiography to assess the prevalence of renal artery stenosis in a group of patients with hypertension and type 2 diabetes mellitus and compared them with a group of hypertensive patients without diabetes.

METHODS

One hundred and seventy-three individuals were recruited consecutively in this study. They were divided into two groups: 50 patients with known type 2 diabetes and coexistent hypertension in group A and 123 hypertensive patients without diabetes in group B. All the patients underwent magnetic resonance angiography of the renal arteries to assess the presence of renal artery stenosis.

RESULTS

The prevalence of renal artery stenosis in groups A and B was 44% and 35.8%, respectively (P=0.402). However, there was a significant association between the age and renal artery stenosis (P=0.023).

CONCLUSION

Diabetes mellitus was not associated with the increased prevalence of renal artery stenosis in our study.

[Atheroembolic renal disease]

Atheroembolic renal disease can be defined as renal failure due to occlusion of the renal arterioles by cholesterol crystal emboli usually dislodged from ulcerated atherosclerotic plaques of the aorta. Atheroembolic renal disease is part of multisystem disease, since the embolization usually involves other organ systems such as the gastrointestinal system, central nervous system, and lower extremities. The kidney is frequently involved because of the proximity of the renal arteries to the abdominal aorta, where erosion of atheromatous plaques is most likely to occur. Embolization may occur spontaneously or after angiographic procedures, vascular surgery, and anticoagulation. In the last decade, atheroembolic renal disease has become a recognizable cause of renal disease. An ante-mortem diagnosis of the disease is possible in a significant proportion of cases as long as the level of diagnostic suspicion is high. The disease can severely affect kidney and patient survival. Although no specific treatment has been proven efficacious, use of statins may be justifiable and such therapy would be a reasonable choice for future treatment trials.

[Acute renal failure as atypical complication of atrial fibrillation]

We present a case of a 76-year-old woman with persistent atrial fibrillation, recent diagnosis of ischemic stroke and embolic occlusion of the iliac artery, who was admitted to our department with symptoms of acute renal failure. Using the data from medical history, physical examination, ECG, laboratory tests (urinalysis, LDH in serum and urine) and radiologic studies (color Doppler ultrasound, angio-CT) we diagnosed renal artery embolus and infarct of solitary functioning kidney. We presumed that this complication was related to the inadequate anticoagulation in the course of atrial fibrillation. Patient received intravenous heparin followed by oral warfarin and started renal replacement therapy.