What are the causes of bilateral renal artery stenosis?

Causes of Bilateral Renal Artery Stenosis

Atherosclerosis is the most common cause of bilateral renal artery stenosis, accounting for approximately 90% of all renovascular stenotic lesions. 1

Primary Causes

Atherosclerotic Disease

• Atherosclerotic renal artery disease (RAD) is the predominant cause of bilateral renal artery stenosis, especially in older patients 1
• Risk factors for atherosclerotic renal artery stenosis include:
  • Advanced age 1
  • Male gender 1
  • Hypertension 1, 2
  • Smoking 1, 3
  • Diabetes mellitus 1, 4
  • Dyslipidemia 1, 5
  • Chronic kidney disease (CKD) 1
  • Existing aorto-iliac occlusive disease 1
  • Coronary artery disease (CAD), particularly triple-vessel disease 2
• Atherosclerotic lesions typically affect the aorto-ostial segment, including the proximal 1 cm of the main renal artery 1

Fibromuscular Dysplasia (FMD)

• Second most common cause of renal artery stenosis, accounting for approximately 10% of cases 1
• More prevalent in younger patients, especially women 1
• Most common cause of renovascular hypertension in young hypertensive patients 1
• Unlike atherosclerotic disease, FMD typically affects the mid and distal portions of the renal artery 1

Less Common Causes

• Arteritis (inflammatory vascular diseases) 1
• Takayasu arteritis (more common in Asian populations) 1
• Radiation fibrosis 1
• Renal artery dissection or infarction 1
• Renal artery obstruction from aortic endovascular stent grafts 1

Clinical Manifestations of Bilateral Renal Artery Stenosis

• Resistant hypertension (difficult to control with standard medication regimens) 1
• Unexplained renal failure 1
• Flash pulmonary edema (particularly in patients with severe bilateral RAS or unilateral RAS in a single functioning kidney) 1
• Activation of the renin-angiotensin-aldosterone system (RAAS) 1
• Acute kidney injury when treated with ACE inhibitors or angiotensin receptor blockers 1

Diagnostic Considerations

• Duplex ultrasound (DUS) is recommended as the first-line imaging modality to screen for significant stenosis 1
• Further imaging with magnetic resonance angiography (MRA) and/or computed tomography angiography (CTA) is recommended when clinical suspicion is high 1
• Peak systolic velocity in the main renal artery shows the best sensitivity (85%) and specificity (92%) for identifying significant stenoses 1
• Digital subtraction angiography (DSA) remains the gold standard for diagnosis 1

Clinical Implications and Management

• Medical therapy is recommended as first-line treatment for atherosclerotic renal artery stenosis 1
• Revascularization may be considered for patients with:
  • High-grade bilateral renal artery stenosis 1
  • Renal artery stenosis affecting a solitary kidney 1
  • Acute kidney injury 1
  • Marked reductions in GFR with RAAS blockers 1
  • Acute decompensated heart failure 1
  • Progressive deterioration of kidney function with uncontrolled hypertension 1

Prevalence in Special Populations

• Present in 5-10% of the general population, with higher prevalence in high-risk groups 1
• Approximately 20% of patients with renal artery stenosis have bilateral disease 1
• Found in up to 33% of diabetic patients with hypertension and/or renal impairment 4
• Present in 49.1% of patients with peripheral vascular disease 3
• Detected in 24% of older subjects (mean age 71 years) with resistant hypertension 1

Understanding the causes of bilateral renal artery stenosis is essential for proper diagnosis and management, as it can significantly impact treatment decisions, particularly regarding medication choices and the potential need for revascularization in specific patient populations.