Renal artery stenosis

Question 1

what is it?

Answer 1

is a narrowing of the renal artery lumen

significant if more than a 50% reduction

Question 2

Risk factors

Answer 2

Dyslipidaemia
Diabetes
Smoking

weak; female

Question 3

Aetiology?

Answer 3

1. Atherosclerosis (older patients) - widespread aortic disease involving the renal artery ostia
2. Fibromuscular Dysplasia (younger patients)
   Unknown aetiology
   May be associated with collagen disorders, neurofibromatosis and Takayasu’s arteritis.
   May be associated with micro-aneurysms in the mid and distal renal arteries (resembling a string of beads on angiography)

Question 4

What is the pathophysiology of fibromuscular dysplasia?

Answer 4

Renal hypoperfusion (due to the stenosis) stimulates the renin-angiotensin system leading to increased angiotensin II and increased aldosterone

This leads to increased blood pressure

The high blood pressure leads to fibrosis, glomerulosclerosis and renal failure

Question 5

Epidemiology of RAStenosis?

Answer 5

Accounts for 1-5% of all hypertension

Fibromuscular dysplasia occurs mainly in women with hypertension < 45 yrs

Question 6

Brief typical hx of some1 with RAStenosis?

Answer 6

History of hypertension in < 50 yrs

Hypertension refractory to treatment

Accelerated hypertension and renal deterioration on starting ACE inhibitors

History of flash pulmonary oedema (rapid onset)

Question 7

Which drug do we avoid in RAS?

Answer 7

ACE INHIBITORS!!!

Question 8

Signs of RAS on examination?

Answer 8

Hypertension

Signs of renal failure in advanced bilateral disease

Renal artery bruits

Question 9

Invx for RAS?

Answer 9

1.nBloods;
Serum creatinine - high or norm
Serum K+ - low (if aetiology is due to RASystem activation)

2. Duplex ultrasound
   - renal artery narrowing >50%
3. CT Angiogram or MR Angiography: risk of contrast nephrotoxicity
4. Digital Subtraction Angiography = Gold standard???