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For further information, see CMDT Part 22-13: Renal Artery Stenosis

Key Features

Essentials of Diagnosis

  • Produced by atherosclerotic occlusive disease (most patients) or fibromuscular dysplasia

  • Hypertension

  • Acute kidney injury with initiation of angiotensin-converting enzyme (ACE) inhibitor therapy if stenosis is bilateral

General Considerations

  • Atherosclerotic ischemic renal disease

    • Accounts for most cases of renal artery stenosis

    • Occurs most commonly in persons older than age 45 years with additional risk factors such as CKD, diabetes mellitus, and tobacco use

  • Fibromuscular dysplasia is a less common cause

Demographics

  • Approximately 5% of Americans with hypertension suffer from renal artery stenosis

Clinical Findings

Symptoms and Signs

  • Refractory hypertension

  • New-onset hypertension in older patient

  • Pulmonary edema with poorly controlled blood pressure

  • Acute kidney injury upon starting an ACE inhibitor or an angiotensin receptor blocker (ARB)

  • Abdominal bruit on affected side

Differential Diagnosis

  • Hypertensive nephrosclerosis

  • Primary hyperaldosteronism

  • Cushing syndrome

  • Coarctation of the aorta

Diagnosis

Laboratory Tests

  • Elevated blood urea nitrogen and serum creatinine

  • Hypokalemia

    • May be found in patients with bilateral renal artery stenosis

    • Reflects activation of the renin-angiotensin-aldosterone system in response to reduced blood flow (a "prerenal" state)

Imaging Studies

  • Abdominal ultrasound shows asymmetric kidney size

  • Initial screening tests: Doppler ultrasonography, CT angiography, and magnetic resonance angiography (MRA)

  • Doppler ultrasonography

    • Highly sensitive and specific (85% and 92%, respectively, in a meta-analysis of 88 studies) and relatively inexpensive test

    • Poor choice for patients who are obese, unable to lie supine, or have interfering bowel gas patterns

  • CT angiography

    • A noninvasive procedure

    • Consists of intravenous contrast injection with digital subtraction arteriography

    • Sensitivity ranges from 77% to 98% and specificity from 90% to 94%

  • MRA

    • Excellent but expensive test

    • Sensitivity is 77% to 100% and specificity ranges from 71% to 96%

    • Turbulent blood flow can cause false-positive results

    • Its imaging agent, gadolinium, has been associated with nephrogenic systemic fibrosis

  • Renal angiography

    • Gold standard for diagnosis; performed after an initial imaging test result is abnormal

    • Fibromuscular dysplasia has characteristic "beads-on-a-string" appearance

    • CO2 subtraction angiography is used when risk of dye nephropathy exists (eg, diabetic patients with kidney injury)

    • Risk of atheroembolic phenomena after angiography ranges from 5% to 10%

Treatment

Medications

  • Antihypertensive agents, avoiding ACE inhibitors and ARBs

Surgery

  • Surgical bypass (revision) is an option for atherosclerotic ischemic renal disease

Therapeutic Procedures

  • Angioplasty

    • Might reduce number of antihypertensive medications

    • However, does not significantly change the progression of kidney dysfunction

  • Stenting

    • Produces significantly better results than angioplasty

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