Renovascular Disease

Background/Epidemiology

• Impairment of renal perfusion caused by disease affecting the arterial supply to the kidneys
• Typically affects white male patients, >50 with coexistent vascular disease elsewhere.
  • up to 30% of patients high-risk for vascular disease, up to 20% in patients with T2DM; up to 50% in males >70 years old (incidence increases with age)

Risk factors/Aetiology

• Hypertension
• Age; male
• Peripheral vascular disease; cardiovascular disease; cerebrovascular disease
• Diabetes Mellitus
• Smoking
• Family History of vascular disease
• Hyperlipidaemia

Pathophysiology

• Narrowing of the renal artery typically occurs due to atherosclerosis.  Significant reduction of renal flow occurs when there is >70% narrowing.
  • This causes reduced renal perfusion and thus the release of renin (and activation of the renin-angiotensin-aldosterone system (RAAS))
  • This causes a rise in blood pressure, hypokalaemia and hyponatraemia
  • Secondary hypertension can cause further progression of the atherosclerotic process and thus further narrowing of the renal artery.
  • This can eventually cause shrinkage of the kidney and renal ischaemia
• Occasionally, particularly in younger, healthy, female patients, fibromuscular dysplasia is a more likely cause.
  • Characterised by hypertrophy of the vessel media which narrows the artery (rarely occludes)
• Most patients do not develop kidney impairment.

Presentation

• Hypertension
  • Often severe, semi-acute onset, refractory
  • When treated with an ACEI or ARB, there is often evidence of a deterioration in renal function and patients with bilateral disease may even go into Acute renal failure
• May also present with features of chronic kidney disease
  • e.g. proteinuria, (flash pulmonary oedema is an uncommon diagnostic feature)
• There may be evidence of other arterial disease e.g. peripheral artery disease, coronary heart disease etc
• Abdominal (and other) bruits may be heard on auscultation

Features/pointers to diagnosis of RAD: Young, hypertensive patients with no family history (fibromuscular dysplasia)
Peripheral vascular disease
Resistant Hypertension
Deterioration in blood pressure control in compliant, long-standing hypertensive patients
Deterioration in renal function with ACEIs
Renal impairment with minimal proteinuria
Flash pulmonary oedema
>1.5cm difference in kidney size on USS
Secondary hyperaldosteronism (low sodium and potassium)

Investigations

• Bloods
  • Renal function- U&Es; eGFR
  • Blood glucose
  • Lipids
• Urine
  • Urinalysis
  • Urinary protein-creatinine ratio
• Renal USS and Duplex renal ultrasound is recommended by European guidelines.  However, contrast CT angiography is often much more accurate (although is not suitable for patients with kidney failure)

Management

• Control risk factors
  • manage blood pressure (CCBs, ARBs and ACEIs are good BUT
    • introduce ACEIs with caution as they can reduce glomerular hydrostatic blood pressure and induce kidney failure
    • Contraindicated in bilateral (or unilateral with a single functional kidney) disease
  • statin
  • smoking cessation
  • aspirin
• Revascularisation procedures (balloon angioplasty- endovascular)
  • Particularly in patients with refractory hypertension, flash pulmonary oedema, malignant hypertension, acute heart failure etc
  • Patients should have >60% occlusion
  • NB No good evidence to suggest this improves renal function or blood pressure, and the procedure does carry risk of renal artery occlusion, infarction and atheroemboli.
• NB For patients with fibromuscular dysplasia, revascularisation is more beneficial and should be considered more readily