Renal Artery Stenosis

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Information about Renal Artery Stenosis
Health & Medicine

Published on March 14, 2014

Author: KhalafAlGhamdi



Renal Artery Stenosis

K H A L A F S . A L G H A M D I , M B B S R H E U M A T O L O G Y U N I T O F M E D I C I N E K K U H M O N D A Y 2 4 F E B R U A R Y 2 0 1 4 Renal Artery Stenosis

Definitions  Renal artery stenosis is narrowing or complete occlusion of one or both renal arteries, defined by radiograph imaging at  greater than 60% stenosis on renal Doppler or  greater than 50% on angiography  Ischaemic nephropathy is a chronic reduction in GFR that occurs from a narrowing in the renal artery.  Renovascular HTN (RVHTN) is HTN mediated by high levels of renin and angiotensin II, produced by an underperfused kidney behind a stenosed renal artery.

Epidemiology  RAS has a prevalence of 0.2% to 5% in all hypertensive patients.  Atherosclerotic RAS accounts for 90% of all RAS.  Prevalence is as high as 25% in patients with CAD  2% of ESRD pts is due to ischemic nephropathy  More common in people aged older than 50 years  Found more commonly in women than in men  Fibromuscular dysplasia accounts for 10% of clinical RAS  Females are 2 to 10 times more likely than males  Onset typically occurs before the age of 30

Aetiology  Atherosclerotic RAS:  Atherosclerosis  Diabetes mellitus  Dyslipidemia  Smoking  Fibromuscular dysplasia:  Medial fibroplasia (histological finding in 90% of cases)  Intimal and adventitial fibroplasia (less common)  Smoking  Other causes:  Post-transplant (site of vascular anastomosis)  Miscellaneous renal arterial disease  Renal artery aneurysm  Accessory renal artery  Takayasu's arteritis  Atheroemboli  Thromboemboli  Williams syndrome  Neurofibromatosis  Spontaneous renal artery dissection  Arteriovenous malformations  Arteriovenous fistulas  Trauma  Abdominal radiotherapy  Retroperitoneal fibrosis.

Pathophysiology  When the stenosis exceeds 50% reduction in vessel diameter  underperfusion of the kidney  the regulatory mechanism (renin-angiotensin system) fail  vascular resistance & sodium retention  worsening kidney function & difficult-to-control HTN  RAS   Atrophy of tubular cells  Fibrosis of the capillary tuft  Intra-renal arterial medial thickening.

Classification  Anatomical:  Unilateral  Unilateral in a single functional kidney  Bilateral  Proximal  Distal  Severity:  Moderate stenosis (≥50% of RA diameter)  Severe stenosis (≥75%)  Total occlusion (100%)

Presentation Signs & Symptoms:  or in urination  edema, usually in the legs, feet, or ankles  drowsiness or tiredness  generalized itching or numbness  dry skin  headaches  weight loss  appetite loss  nausea  vomiting  sleep problems  trouble concentrating  darkened skin  muscle cramps  In many cases, RAS has no symptoms until it becomes severe.

Diagnosis  RAS should be considered if  Age <30 or >50 when they developed HTN  NO FHx of HTN  Refractory hypertension (No improvement with using 3 or more of Anti HTN medications)  Clinically (bruit on auscultation)  Labs:  Serum creatinine  Serum potassium  Urine analysis and sediment evaluation  Aldosterone-to-renin ratio  Duplex ultrasound (US + Doppler)  Catheter angiogram  Computerized tomographic angiography (CTA) scan  Magnetic resonance angiogram (MRA)

Duplex Ultrasound

Catheter Angiogram

Computerized Tomographic Angiography

Magnetic Resonance Angiogram


Treatment  Atherosclerotic patient group:  1st line: Antihypertensive therapy + Life style modification + Statin + Antiplatlet agents  2nd line: stenting + medical therapy + clopidogrel  3rd line: surgery  Fibromascular dysplasia :  1st line: Antihypertensive therapy + Life style modification + percutaneous renal artery balloon angioplasty  2nd line: Surgery + renal artery stenting and dual antiplatelet therapy

 British Journal of Medicine, “RAS” • practice/monograph/435/highlights/summary.html  UpToDate, “RVHTN” • renovascular- hypertension?source=search_result&search=renal+artery+stenosis&se lectedTitle=1~150  Medscape, “RAS” •  MedicineNet, “RAS” •

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