Renovascular disease

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Renal artery stenosis

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Etiology & Pathophysiology

Causes of Ischemic Renal Disease

  • Atherosclerotic Renal Artery Stenosis (ARAS)
    • Atherosclerosis accounts for approximately 90% of the cases of RAS and is the predominant lesion detected in patients >50 years of age
    • The presence and number of diseased coronary arteries predicts the likelihood of ARAS
    • RAS resulting from atherosclerotic disease is common in (18% to 20%) individuals undergoing coronary angiography (1)
    • RAS resulting from atherosclerotic disease is even more common (35% to 50%) in individuals undergoing peripheral vascular angiography for occlusive disease of the aorta and legs (2)
  • Fibromuscular dysplasia
    • Unknown etiology
    • Second most common cause of RAS
    • Affects middle-aged women
    • More common in first-degree relatives and in the presence of the ACE-I allele.
    • Renal artery involvement is seen in 60% of cases - frequently bilateral compromise.
    • Progressive renal stenosis is seen in 37% of cases and loss of renal mass in 63%
  • Nephroangiosclerosis (HTN injury)
  • Diabetic Nephropathy (small vessels)
  • Renal thromboembolic disease
  • Atheroembolic renal disease
  • Aortorenal dissection
  • Post renal transplant RAS
  • Renal artery vasculitis
  • Trauma
  • Neurofibromatosis
  • Thromboangiitis obliterans
  • Scleroderma

Incidence

  • Prevalence of Renal Artery Stenosis
    • Most Common Cause of HTN
  • Incidence of Renal Artery Stenosis at Cardiac Catheterization

Diagnosis

  • Manifestations of Renovascular Disease (3)
    • Asymptomatic "Incidental RAS"
    • Renovascular Hypertension
    • Ischemic Nephropathy
    • Accelerated CV Disease
      • Congestive Heart Failure
      • Stroke
      • Secondary Aldosteronism

Clinical Clues to the Diagnosis of Renal Artery Stenosis-ACC/AHA Guidelines

  • CLASS I
    • Onset of hypertension before the age of 30 years or severe hypertension after age 55; level of evidence B
    • Accelerated, resistant, or malignant hypertension; level of evidence C
    • Development of new azotemia or worsening renal function after administration of an ACE inhibitor or ARB agent; level of evidence B
    • Uneaplained atrophic kidney or sizse discrepancy between kidnyes of >1.5cm; level of evidence B
    • Sudden, unexplained pulmonary edema; level of evidence B
  • CLASS IIa
    • Unexplained renal dysfunction, including individuals starting renal replacement therapy; level of evidence B
  • CLASS IIb
    • Multivessel coronary artery disease; level of evidence B
    • Unexplained congestive heart failure; level of evidence C
    • Refractory angina; level of evidence C

Diagnostic Methods to Detect Renal Artery Stenosis - ACC/AHA Guidelines

  • CLASS I
    • Duplex ultrasound sonography is recommended as a screening test to establish the diagnosis of renal artery stenosis; Level of eveidence: B
    • Computed tomographic angiography(in individuals with normal renal function) is recommended as a screnning test to establish the diagnosis of renal artery stenosis; Level of eveidence: B
    • Magnetic resonance angiography is recommended as a screening test to establish the diagnosis of renal artery stenosis; Level of eveidence: B
    • When the clinical index of suspicion is high and the results of noninvasive tests are inconclusive, cathether angiography is recommended as a diagnostic test to establish teh diagnosis of renal aretry stenosis; Level of eveidence: B
  • CLASS III
    • Captopril renal scintigraphy is not recommended as a screening test to establish the diagnosis of renal artery stenosis; Level of eveidence: C
    • Selective renal vein measurements are not recommended as a useful screening test to establish the diagnosis of RAS; Level of eveidence: B
    • The plasma renin activity is not recommended as a useful screening test to establish the diagnosis of RAS; Level of eveidence: B
    • The captopril test (measurements of plasma renin activity following captopril administration) is not recommended as a useful screening test to establish the diagnosis of renal artery stenosis; Level of eveidence: B

Indications for Revascularization

  • Reasons to Revascularize Atherosclerotic Renovascular Disease
    • Treat Symptoms
    • Prevent Future Illness
    • Lower BP
    • Preserve Renal Function
    • “Bystander” Effects
      • Prevent Death
      • Prevent MI
      • Prevent CHF
      • Prevent CVA
  • Indications for revascularization of RAS
    • hypertension
      • Failure of medical therapy despite full doses of 3 drugs, including diuretic
      • Compelling need for ACE inhibition/angiotensin blockade with angiotensin-dependent GFR
    • Progressive renal insufficiency with salvagable kidneys
      • Recent rise in serum creatinine
      • Loss of GFR during antihypertensive therapy (e.g., ACEI)
      • Evidence of preserved diastolic blood flow (low resistive index)
    • Circulatory congestion, recurrent “flash” pulmonary edema
    • Refractory congestive heart failure with bilateral renal artery stenosis

Treatment Options

Medical Therapy

PTA

Surgical

Technical Considerations

Renal Arteriography

  • Abdominal Aortogram: identification of ostia of the renal arteries and accessory renal arteries (25% of population)
  • Arteriography should include both the arterial phase and the nephrographic phase
  • Disease involving renal bifurcations require cranial or caudal angulation to open out the lesion
  • Evidence of aortic atheroma: technique of no-touch angiography is recommended

Brachial Approach

  • For renal arteries that are oriented cephalad.
  • When the aorta is occluded distally or the renal artery takeoff is severely angulated
  • Proximal renal artery segment initially courses inferiorly and posteriorly braquial approach allows more coaxial alignment.
  • Greater incidence of vascular site complications

Femoral approach

  • Renal artery angioplasty and stenting are usually performed via retrograde femoral approach.
  • When the real artery origin is oriented horizontally or caudally with respect to the aorta, femoral approach is preferred.

Complications

Complications of Percutaneous Renal Revascularization

  • Atheroembolism into the renal or peripheral vascular bed = cholesterol embolization
  • Dissection of renal artery or the wall of the aorta
  • Acute or delayed thrombosis
  • Infection
  • Rupture of renal artery
  • Renal perforation

Prognosis

Favorable Predictors

Successful Outcome For Control Of Hypertension

  • Rapid acceleration of hypertension over the prior weeks or months
  • Presence of “malignant” hypertension
  • Hypertension in association with flash pulmonary edema
  • Contemporaneous rise in serum creatinine
  • Development of azotemia in response to ACE inhibitors administered for control of hypertension.

Successful Salvage Or Preservation Of Renal Function

  • Recent rapid rise in creatinine, unexplained by other factors
  • Azotemia resulting from ACE inhibitors
  • Absence of diabetes or other cause of intrinsic kidney disease
  • Presence of global renal ischemia, wherein the entire functioning renal mass is subtended by bilateral critically narrowed renal arteries or a vessel supplying a solitary kidney.

Unfavorable Predictors

  • Renal atrophy demonstrated by kidney length <7.5 cm on ultrasound
  • High renal resistance index detected by duplex ultrasound
  • Proteinuria > 1gm/day
  • Hyperuricemia
  • Creatinine clearance <40 mL/minute

References

  1. PMID 11936924
  2. PMID 12472042
  3. PMID 16129817


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