Renal Artery Stenosis

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Contents 1 Introduction 2 Epidemiology 3 Pathology 4 Clinical-manifestations 5 Laboratory 6 Diagnostic-procedures 7 Radiology 8 Complications 9 Management 10 More General Terms 11 Additional Terms 12 References

Introduction

• Etiology:
• atherosclerotic plaques*
• fibromuscular dysplasia, stenosis*

• more common in women
• patients under 50

• thrombosis
• embolism
• renal arterial dissection/ aneurysm
• arteritis
• extrinsic compression
• occlusion by foreign body
• coarctation of aorta
• arteriovenous fistula
• post irradiation stenosis
• post transplant stenosis

• * 2 most common causes

Epidemiology

• uncommon
• atherosclerotic disease: > 50 years of age
• fibromuscular dysplasia: < 30 years of age

Pathology

• the perceived reduction in renal perfusion results in release of renin & activation of the renin-angiotensin-aldosterone axis

Clinical-manifestations

• epigastric, subcostal or flank bruits
• accelerated hypertension
• unilateral small kidney
• sudden development or worsening of hypertension

• diastolic blood pressure > 120 mm Hg

• hypertension & unexplained renal failure
• hypertension refractory to 3-drug medical therapy
• impairment of renal function in response to ACE inhibitor
• extensive atherosclerosis evident in other organ systems
• flash pulmonary edema with uncontrolled hypertension
• high-grade hypertensive retinopathy
• ischemic nephropathy - glomerulonephritis
• secondary hyperaldosteronism

Laboratory

• increased serum aldosterone

Diagnostic-procedures

• renal vein renin levels

• ratio involved/ contralateral side > 1.5 suggests significant lesion

• renin activity weighted analysis point system
• screening for renovascular hypertension (sensitivity/ specificity)

• captopril test 95/95
• captopril scan ( scintigraphy) 80/100
• renal scan 75/75
• IVP 75/85
• digital subtraction angiogram 90/90
• renal vein renin 75/95

Radiology

• captopril scan for screening (33-47/92-88)*
• renal angiography for fibromuscular dysplasia ( gold standard)*
• gadolinium-enhanced magnetic resonance angiography ( MRA) (90-95/80-82)*#
• captopril enhanced doppler sonography (63-79/95-80)*
• computed tomographic angiography [10]
• digital subtraction angiography [10]

• * sensitivity/ specificity (50% - >70% stenosis) relative to angiography
• # test of choice, Veterans Administration, Mather

Complications

• unilateral or bilateral renal artery stenosis can cause hypertension refractory to antihypertensives

Management

• NOT ALL cases of hypertension & renal artery stenosis are due to renovascular disease; the two conditions can coexist
• many patients can control blood pressure with medical therapy
• angioplasty
• stent placement no better than medical therapy for atherosclerotic renal artery stenosis [8,9]
• aggressive control of cardiovascular risk factors

• control of hypertension

• use of ACE inhibitors or ARBs controversial
• earlier literature recommends avoiding ACE inhibitors
• ref [2] recommends ACE inhibitors or ARBs

• statins & antiplatelet therapy ( clopidogrel or aspirin) may be used to treat peripheral vascular disease [6]
• control of diabetes mellitus
• diet & life style measures

• weight reduction 2[ smoking cessation

More General Terms

• arterial stenosis
• kidney disease; renal disease

Additional Terms

• fibromuscular dysplasia
• renal artery

References

1. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 277
2. Medical Knowledge Self Assessment Program (MKSAP) 11, 15, American College of Physicians, Philadelphia 1998, 2009
3. Journal Watch 20(13):103, 2000
4. Journal Watch 21(20):161-62, 2001 Vasbinder et al, Ann Intern Med 135:401, 2001
5. Journal Watch 22(1):2, 2002 Qanaduu et al, AJR Am J Roentgenol 177:1123, 2001
6. Balk E et al, Effectiveness of management strategies for renal artery stenosis: a systematic review. Annals of Intern Med 2006, 145:901 PMID: [1]
7. van Jaarsveld BC et al, The effect of balloon angioplasty on hypertension in atherosclerotic renal-artery stenosis. N Engl J Med 2000, 342:1007 PMID: [2]
8. Bax L et al Stent Placement in Patients With Atherosclerotic Renal Artery Stenosis and Impaired Renal Function Annals of Internal Medicine, 2009 150(12)840-848 <PubMed> PMID: [3] <Internet> [4]
9. Wheatley K et al for The ASTRAL Investigators. Revascularization versus medical therapy for renal-artery stenosis. N Engl J Med 2009 Nov 12; 361:1953. PMID: [5]
10. Dworkin LD, Cooper CJ. Clinical practice. Renal-artery stenosis. N Engl J Med 2009; 361:1972-1978; November 12, 2009. PMID: [6]
11. National Guideline Clearinghouse Procedure guideline for diagnosis of renovascular hypertension. Society of Nuclear Medicine, Inc ngc-guideline: [7]
    - Renovascular hypertension. (American College of Radiology) ngc-guideline: [8]
    - Renal artery stenosis Caring for Australasians with Renal Impairment ngc-guideline: [9]

renal artery stenosis (RAS)