Renal Artery Stenosis

1. 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

2. 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.

3. 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

4. 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.

5. 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.

6. 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%)

7. 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.

8. 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)

9. Duplex Ultrasound

10. Catheter Angiogram

11. Computerized Tomographic Angiography

12. Magnetic Resonance Angiogram

13. Treatment

14. 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
http://bestpractice.bmj.com/best-practice/monograph/435/treatment/details.html

15.  British Journal of Medicine, “RAS”
• http://bestpractice.bmj.com/best-
practice/monograph/435/highlights/summary.html
 UpToDate, “RVHTN”
• http://www.uptodate.com/contents/establishing-the-diagnosis-of-
renovascular-
hypertension?source=search_result&search=renal+artery+stenosis&se
lectedTitle=1~150
 Medscape, “RAS”
• http://emedicine.medscape.com/article/245023-overview
 MedicineNet, “RAS”
• http://www.medicinenet.com/renal_artery_stenosis/article.htm