Description

Narrowing of one or both renal arteries and/or their more distal branches, resulting in decreased perfusion, increased renin release, increased vascular resistance, and systemic hypertension

Epidemiology

• Hypertension in infants and young children is often secondary to some identifiable cause. Of those with secondary hypertension, most have intrinsic renal disease (e.g., renal scarring, dysplasia, chronic nephritis).
• Up to 5% of adults with hypertension have renal artery stenosis (RAS).
• RAS accounts for ~10% of secondary hypertension in children. Its importance clinically is not its frequency but its potential curability.

Risk Factors

• Any condition associated with thromboembolic events (such as a complication of an umbilical artery catheter in newborns)
• Renal trauma including renal artery surgery (e.g., transplantation)
• Extrinsic compression of the renal artery (e.g., Wilms tumor, neuroblastoma, or pheochromocytoma)
• Underlying vascular disease such as midaortic syndrome, Williams syndrome, or Takayasu arteritis

General Prevention

Reduce risk factors, such as thromboembolic events, which can lead to renal artery narrowing.

Pathophysiology

Arterial narrowing leads to diminished perfusion of the affected kidney, leading to signals in the juxtaglomerular apparatus, which lead to renin release and results in increased vascular resistance, sodium retention, and blood pressure (BP).

Etiology

• Majority are caused by fibromuscular dysplasia (FMD), a noninflammatory vascular disease of unknown etiology.
  • Primarily affects females and affects up to 4 in 100 adults
  • The renal vasculature is the most common arterial bed affected.
  • FMD can concurrently affect other vascular beds including carotid, vertebral, and intracranial vascular beds.
• Arterial narrowing by atheroma is common in adults but rare in children.

Commonly Associated Conditions

• Renal artery hypoplasia
• Neurocutaneous disorders (neurofibromatosis [type 1], tuberous sclerosis)
• Vasculitis (granulomatous polyangiitis, polyarteritis nodosa, Kawasaki disease, Takayasu arteritis, moyamoya disease)
• Williams syndrome
• Marfan syndrome
• Alagille syndrome
• Infections (e.g., congenital rubella, fungal infection)
• Nephrotic syndrome may accompany RAS and is probably secondary to it.
• RAS has been associated with multicystic dysplasia in the contralateral kidney.