Renal Artery Stenosis

Question 1

Define

Answer 1

Stenosis of the renal artery

• Aka. Renovascular disease

1. Renal hypoperfusion stimulates the renin-angiotensin system
2. (RAS), leading to ↑circulating Angiotensin II and aldosterone
3. Leads to an ↑BP – which in turn causes fibrosis glomerulosclerosis and renal failure
4. Important cause of 2ndary HTN and chronic kidney disease

Question 2

Causes

Answer 2

1. 80% Atherosclerosis (in older pts) – widespread aortic disease, often coexistent with IHD, stroke, PVD
2. 10% Fibromuscular dysplasia (younger pt) – fibromuscular disorder of unknown aetiology associated with collage disorders, NF and Takayasu’s disease
   ±Microaneurysms in mid/distal renal arteries

Rarer: Takayasu’s arteritis (India and Far-East), antiphospholipid syndrome, post-renal transplant, thromboembolism, external compression

Question 3

Risk factors

Answer 3

HTN, ↑age, DM, smoking, FHX CV disease or renovascular disease, ↑lipids
Evidence of renal impairment or CV disease

Question 4

Epidemiology

Answer 4

high prevalence (7% in >65 years)
More common in white racial background
Fibromuscular dysplasia: mainly in women with HTN <45 years

Question 5

Symptoms

Question 6

Signs

Answer 6

• HTN
• Signs of renal failure in advanced bilateral disease
• Abdominal bruit over stenosed artery ±carotid/femoral bruits, weak leg pulses
• Look for evidence of vascular risk factors (e.g. xanthoma, xanthelasma, ↑BP, corneal arcus)
• Ophthalmoscopy to show any hypertensive retinopathy

Question 7

Investigations

Answer 7

Non-Invasive

• Duplex ultrasound
• Ultrasound measurement of kidney size

CT Angiogram or MR Angiography: risk of contrast nephrotoxicity

Digital Subtraction Angiography = GOLD STANDARD

Renal Scintigraphy

• Uses radio-agent that is either excreted by glomerular filtration or by the tubules
• Addition of an ACE inhibitor causes delayed clearance by the affected kidney (may not be useful in bilateral renal artery stenosis)