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Renal artery stenosis/aneurysm

Criteria for workup of renovascular HTN

• Severe/refractory HTN with Grade III-IV hypertensive retinopathy
• Sudden onset moderate/severe HTN in previously normotensive or well-controlled hypertensive
• HTN before 20yo or after 50yo
• Unexplained worsening renal function with(out) HTN or after starting ACEi/ARB or with improved BP with other antiHTN medications
• Worsening HTN with diuretics
• Unexplained recurrent heart failure episodes
• Abdominal bruit that radiates bilaterally
• Diffuse vascular disease and/or cholesterol emboli

Renal artery stenosis

• Definition: narrowing of renal artery > 50% normal luminal diameter
• Most common cause of renovascular HTN
• 60-80% are atherosclerotic, the remainder are fibromuscular dysplasia
• Causes 5-15% total renal failure in ages > 50
• Imaging: duplex ultrasonography is best screening test, arteriography is gold standard, consider CT/MR

RAS Management

• Unilateral stenosis: induces HTN due to normal kidney excreting water/salt and vasoconstriction from angiotensin, resolves with treatment of stenosis, ACEi/ARB
• Bilateral stenosis: induces HTN due to inability to excrete water/salt and subsequent volume expansion, resolves with treatment of stenosis
• AntiHTN meds can cause renal ischemia distal to obstruction, monitor renal function
• Percutaneous transluminal renal artery angioplasty (PTRA): dilation with balloon, optimal lesions are < 1cm, partially occluded, and not involving ostium, restenosis rates 15-25%
• Stenting: unclear benefit, still require medical therapy
• Surgery: indicated for aneurysmal/occlusive aortic disease, macroaneurysms, or rapidly worsening HTN/renal function
• Monitoring: screen with doppler US and labs to assess for changes in renal function

Renal artery aneurysms

• Usually asymptomatic (incidentally diagnosed on CT/XR), may present with flank pain, hematuria, or HTN
• Asymptomatic repair criteria: ≥ 2cm, uncontrolled/resistant HTN, potential future pregnancy
• Symptomatic repair criteria: perinephric/retroperitoneal bleeding, renal ischemia/infarction, gross hematuria
• Management: open repair, robotic repair, endovascular stenting/occlusion

Fibromuscular Dysplasia

Fibromuscular dysplasia types

Type	% total	Cause	Demographic	Location	Angiographic appearance	Progression?	Renal Failure?
Medial fibroplasia	75-85%	Medial layer fibrosis	Women 25-50yo	Distal renal artery extending into branches	String of beads	Minimal	No
Perimedial fibroplasia	10-25%	Collagen deposits in outer medial layer	Women 5-15yo	Midrenal artery extending into branches	String of beads	Yes (occlusion)	Yes
Intimal fibroplasia	10%	Collagen deposits in intimal layer	Children and young adults	Proximal renal artery	Stenosis with distal aneurysm/dissection	Yes (occlusion)	Yes
Medial hyperplasia	2-3%	Smooth muscle hyperplasia without fibrosis

Management

• Medications: continue medical management if long-standing HTN, all patients should take ASA 81
• PTRA: young/healthy patients prior to HTN onset, or for patients with poorly controlled HTN
• Monitoring: labs, BP checks, and doppler US to assess for worsening or recurrence