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  • • Caused most often by renal artery stenosis (RAS)

    • -67% caused by atherosclerosis

      -33% fibromuscular dysplasia

    • Rare causes of renovascular hypertension

    • -Renal artery aneurysms

      -Emboli

      -Dissections

      -Hypoplastic renal arteries and stenotic proximal aorta

    • Juxtaglomerular complex secrete increased renin resulting in increased angiotensin II, aldosterone levels; leads to chronic changes in kidneys

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Atherosclerosis

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  • • Stenosis at orifice of main renal artery

    • Usually starts in aorta extends into renal artery, rarely originates in renal artery

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Fibromuscular Dysplasia

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  • • Involves middle to distal 33% of renal artery

    • Medial dysplasia most common (85%)

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Epidemiology

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  • • 23% of Americans have hypertension

    • 2-7% of hypertension is caused by renovascular disease

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Atherosclerosis

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  • • More common in males older than 45 years, bilateral in 95%

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Fibromuscular Dysplasia

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  • • Bilateral in 50%

    • Primarily in women

    • Hypertension often occurs before age 45

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Symptoms and Signs

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  • • Most asymptomatic

    • Irritability, headache, depression

    • Persistent elevation of diastolic blood pressure

    • Bruit frequently present in abdomen

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Imaging Findings

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  • Intravenous pyelography (IVP)

    • -Common screening test to compare 2 kidneys

      --Atrophic kidney suggests diagnosis

    Renal arteriography

    • -Most precise for delineating obstructive lesion

      -Perform for high clinical suspiscion, worsening renal function

      -Collateral renal vessels suggest > 10 mm Hg pressure gradient across stenoses

      -Minimize contrast to avoid contrast nephropathy

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  • • Consider this diagnoses for early-onset hypertension, antihypertensive drug resistance, deterioration of renal function, diastolic blood pressure > 115 mm Hg, deterioration of renal function with ACE inhibitors

    • Selective renal vein blood renin levels

    • -Renal vein renin ratio (RVRR): Involved kidney to uninvolved kidney; > 1.5 is diagnostic

    • RVRR not accurate if bilateral RAS

    • Captopril stimulation test causes drop in blood pressure in renin-dependent hypertension

    • Captopril renal scintigraphy: Preferred study to establish diagnosis

    • Duplex US

    • -Up to 90% sensitive

      -Peak systolic velocities in renal artery > 180 cm/s suggests diagnosis

    • Magnetic resonance angiography (MRA) with gadolinium avoids nephrotoxicity, overestimates stenosis

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  • • IVP, duplex may be used for screening

    • Arteriogram or MRA should be performed prior to any surgical intervention

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  • • Primarily treated with medical therapy

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Surgery

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  • Endarterectomy: If lesion focal and close to aorta

    Arterial replacement

    • -Preferred for fibromuscular dysplasia

      -Saphenous vein or hypogastric artery are preferred

    • Splenorenal, iliorenal, hepatorenal bypasses are nonanatomic bypasses with good results

    • Nephrectomy should be considered if unilateral and atrophic kidney

    • Percutaneous angioplasty/stent best for focal lesions distant from aorta; patients with fibromuscular dystrophy preferred

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Indications

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  • • Extent of disease in renal arteries

    • Poor response to medical therapy

    • Associated arterial disease

    • Patient's life expectancy

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Prognosis

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  • • Percutaneous transluminal angioplasty ...

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