Renal artery stenosis Flashcards
Define renal artery stenosis
The narrowing of the renal artery lumen
What are the main causes of renal artery stenosis?
- Atherosclerotic plaque build up
2. Renal fibromuscular dysplasia
Which cell responds to sodium concentration in the tubule and how does it change the blood pressure?
Low sodium levels are detected by the macula densa cells lining the tubule. They release a prostaglandin in response that activate the juxtaglomerular cells to release renin.
Renin causes the blood vessels to constrict and also reabsorb more sodium = increases blood pressure
What is the pathophysiology of renal artery stenosis?
- The narrowed renal artery means the blood pressure to the kidney is low.
- The kidney responds by releasing renin, which increases blood pressure in the body.
- However, the narrowed artery still means the blood pressure to the kidney is low, which causes a viscious cycle of more renin being released = hypertension
- The reduced blood supply to the kidney also causes renal atrophy and scar tissue formation.
Can someone with renal artery stenosis get acute kidney failure?
Yes if both kidneys are affected
What is the epidemiology of renal artery stenosis?
- 5% of all hypertensive patients have RAS
- 90% of patients get RAS due to atherosclerosis
- 10% of patients get RAS because of renal fibromuscular dysplasia
What is the appearance of the renal artery in renal fibromuscular dysplasia?
String of beads appearance
What are the presenting symptoms of a patient with RAS?
- History of hypertension
What are the signs of RAS on physical examination?
- Renal artery bruits
- Hypertension
- Signs of renal failure in bilateral disease
What are the appropriate investigations for RAS?
- Serum creatinine - normal or elevated
- Urinanalysis
- USS of kidney
- CT angiogram
What are the risk factors for RAS?
- Dyslipidaemia
- Obesity
- Smoking
- Female for renal fibromuscular dysplasia
