Fibromuscular dysplasia

Renal artery stenosis secondary to atherosclerosis accounts for around 90% of renal vascular disease, with fibromuscular dysplasia being the most common cause of the remaining 10%.

• Noninflammatory and nonatherosclerotic condition caused by abnormal cell development in the arterial wall that can lead to vessel stenosis, aneurysm, or dissection.

Epidemiology

• 90% of patients are female (age 15-50)

Clinical presentation

• Resistant HTN from renal artery involvement
• Renal: chronic kidney disease or more acute renal failure e.g. secondary to ACE-inhibitor initiation
  • FMD decreases perfusion to the kidneys, which increases both renin and aldosterone levels (secondary hyperaldosteronism)
  • aldosterone concentration to renin activity ratio is ~10 (<20)
• CVS: 'flash' pulmonary oedema
• CNS: brain ischemia (e.g amaurosis fugax, Horner's syndrome, TIA, stroke)
  • Non-specific symptoms (headache, pulsatile tinnitus, dizziness) from carotid or vertebral artery involvement
• can also involve iliac, subclavian and visceral arteries

Investigations

• renal function: CKD or acute rise in creatinine (especially after ACE inhibitor/ARB)
• Doppler ultrasound: first-line imaging (reduced renal blood flow, asymmetry)
• CT angiography or MR angiography: confirms diagnosis
• Catheter-based digital substraction arteriography if inconclusive

Management

• antihypertensive therapy
  • ACE inhibitors or ARBs (with close monitoring of renal function)
  • F-up Medically treated patients with BP and creatinine every 3-4 months & renal ultrasound every 6-12 months
• revascularisation (angioplasty ± stenting)