Renal Artery Stenosis

Renal Artery Stenosis

A. Brad Farris, III, MD

Shown here are a shrunken kidney image affected by renal artery stenosis and a granular kidney image affected by hypertension, likely stimulated by renin production by the shrunken kidney.

There are numerous sclerotic, closely approximated glomeruli image and tubular atrophy in a thyroidization pattern image in this kidney affected by renal artery stenosis.



  • Renal artery stenosis (RAS)


  • Atherosclerotic renovascular disease: Certain cases of RAS

  • Fibromuscular dysplasia: Selected cases of RAS

  • Renovascular disease


  • Narrowing of renal artery lumen sufficient to cause ischemic changes in kidney and hypertension


Causes of RAS

  • Atherosclerosis

    • Most common cause of occlusion/stenosis of large renal arteries (70-90% of RAS cases)

    • Autopsy studies show RAS in 5-42% of patients

    • Up to 50% of patients with extensive peripheral vascular disease have RAS

    • RAS is bilateral in 33-39%

      • Bilateral RAS has higher incidence of renal failure

    • Patients often have multifocal occlusive vascular disease, including coronary artery disease or peripheral arterial disease

      • Injury is conceptually semiepisodic, leading to “layers” of injury with vessels that are not able to autoregulate, eventually leading to “critical stenosis”

    • Atheromatous plaques

      • More common with age and in those with risk factors (cigarette smoking, HTN, diabetes, hyperlipidemia)

    • Atheroemboli (cholesterol emboli)

      • May occur immediately after or within months of angiographic or surgical procedures involving vessels

      • 0.1-0.8% frequency of symptomatic cholesterol emboli after angiography

      • Incidence of 0.1-3.3% in renal vessels

      • Emboli present in ˜ 31% of patients with aortic aneurysms and ˜ 77% of patients dying shortly after abdominal aortic surgery

  • Thromboembolic

  • Fibromuscular dysplasia

  • Neurofibromatosis

  • Moyamoya disease

  • Takayasu arteritis and other arteritides

  • Dissecting aneurysms of either aorta or renal artery

  • Umbilical artery catheterization in neonates

  • Coarctation of the aorta

  • Irradiation

  • Retroperitoneal fibrosis

  • Compression by tumor

  • Arteriovenous fistula

  • Trauma

Ischemic Renal Disease/Ischemic Nephropathy

  • Fundamental mechanism of injury in RAS

  • Occurs when renal artery has 70-80% or greater stenosis

Goldblatt Kidney

  • Unilateral RAS experimental model developed by Goldblatt has revealed pathophysiology

  • Causes hypertension (HTN) by activation of renal-angiotensin-aldosterone system

    • Ischemic kidney produces renin

    • Increased angiotensin II

      • Increased aldosterone production is stimulated

      • Leads to volume retention, hypervolemia, and increased cardiac output

    • Systemic HTN results

      • Ischemic kidney is protected from effects of HTN

      • Contralateral kidney suffers from effects of HTN (arterial and arteriolar nephrosclerosis)



  • Age

    • Atherosclerotic RAS primarily affects older patients

  • Gender

    • 2:1 male to female ratio in atherosclerotic RAS


  • Renal dysfunction

    • Chronic renal insufficiency

      • Increased serum creatinine and blood urea nitrogen

  • Hypertension

  • Proteinuria

    • Usually of low or moderate degree

    • Particularly occurs in patients with focal segmental glomerulosclerosis (FSGS)

  • Retinopathy

  • Abdominal or flank bruits

  • Hypokalemia may sometimes be seen

  • Family history of HTN may be absent

  • Hyperlipidemia, particularly in patients with atherosclerotic RAS

  • Diabetes

  • Congestive heart failure

  • If atheroemboli are associated with RAS

    • Livedo reticularis

    • Acute renal failure

    • HTN

    • Leg pain

    • Gastrointestinal symptoms

    • Vision loss

    • Peripheral eosinophilia

    • Decreased serum complement


  • Surgical approaches

    • Percutaneous transluminal angioplasty

      • Used more often than stent placement

    • Angioplasty

      • Can be coupled with stent placement

      • Particularly useful when stenosis is at renal artery ostium, where angioplasty has higher failure rate

    • Bypass grafts

  • Drugs

    • Antihypertensive agents

      • ACE inhibitors

      • Beta blockers

      • Calcium channel blockers

    • Lipid lowering agents

    • Antidiabetic agents and glucose control


  • With 70-80% narrowing of renal artery lumen, ischemic renal disease may occur and may rapidly progress to failure of affected kidney

    • Around 1/2 progress within 2 years


Radiographic Findings

  • Intraarterial digital subtraction is “gold standard” to demonstrate RAS

  • Other radiographic imaging modalities are useful

    • Magnetic resonance angiography

    • Computed tomographic angiography

    • Color-aided duplex ultrasonography

    • Abdominal aortography

      • If renal artery narrowing, there may be poststenotic dilatation

  • Radiography coupled with renal functional measurements are useful in determining contribution of each kidney to overall renal functioning


General Features

  • Grossly, narrowing of renal artery may be appreciated

    • Origin from aorta involved in approximately 50% of cases

      • Aorta may override renal artery ostium

    • Bilateral disease in up to 60% of cases

    • Can occur from a yellow-white fibroatheromatous plaque (atheroma) in atherosclerotic RAS cases

  • Kidneys may be small in ischemic nephropathy from RAS

    • Most RAS kidneys are < 50% of normal weight

  • Large cortical scars and small cortical cysts may be present

  • Granular capsular surface is often evident because of concurrent arteriolosclerosis

  • Renal cortex is thinned

  • Interlobar and arcuate arteries may appear prominent


Histologic Features

  • Glomeruli

    • Glomeruli may have basement membrane wrinkling

      • Sometimes referred to as an accordion-like wrinkling

      • Particularly appreciable on periodic acid-Schiff (PAS) and silver stains

    • Glomerular capillary tuft may contract toward vascular pole (a process referred to as glomerulus becoming “simplified”), leading to relative increase in Bowman space

    • Intracapsular fibrosis

      • Collagen deposition in Bowman space

      • Occurs 1st near vascular pole, eventually extending toward urinary pole

    • “Atubular glomeruli” may be present

      • Typically are present as residual glomeruli in fibrotic scars

      • Open capillary loops are not attached to tubules on serial sectioning, and mean glomerular volume tends to be larger than in controls

    • FSGS with resultant global sclerosis can occur

      • FSGS occurs as secondary form

      • Proteinuria may be prominent

    • Juxtaglomerular apparatus may be hypertrophic

  • Tubulointerstitium

    • Interstitial fibrosis and tubular atrophy (IFTA), and interstitial inflammation

      • Fibrosis may be diffuse and fine, demonstrable with connective tissue stains (e.g., trichrome)

      • Interstitial fibrosis and inflammation may be more severe in hypertensive nephrosclerosis than in RAS

    • Dilated tubules (“super tubules”)

    • “Classic” atrophic proximal tubules

      • Thickened tubular basement membranes, possibly due to regeneration from repeated tubular injury

      • Numerous mitochondria with decrease in other cellular organelles

    • “Endocrine change” form of atrophic tubules

      • Decreased tubular diameter with narrowed or inconspicuous lumens

      • Cuboidal epithelial cell lining, often with clear cytoplasm

      • Often occur in clusters

      • Terminology derived from resemblance of these renal tubules to endocrine glands such as parathyroid

    • Thyroidization may also be seen, consisting of atrophic tubules filled with proteinaceous cast material

    • Tubular atrophy can be potentially reversible

      • Reversal of atrophy can be accomplished with reestablishment of blood flow in rat model of RAS

      • Atubular glomeruli may be useful prognostic sign (irreversible)

  • Vessels

Jul 7, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Renal Artery Stenosis

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