Renal artery stenosis resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Karol Gema Hernandez, M.D. [2]

Definition

Renal artery stenosis is defined as a dimished diameter of the lumen of the renal artery. Renal artery of >70% is considered hemodynamically significant.

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated. Renal artery stenosis does not have life threatening causes.

Common Causes

• Atherosclerosis
• Fibromuscular dysplasia
• Neurofibromatosis
• Vasculitis
• Congenital bands
• Radiation

Managment of RAS

Clinical Clues to the Diagnosis of RAS

Determine if one or more of the following is present: ❑ Onset of hypertension before the age of 30 years ❑ Onset of severe hypertension after the age of 55 ❑ Accelerated, resistant, or malignant hypertension ❑ Development of new azotemia or worsening renal function after administration of an ACE inhibitor or ARB agent ❑ Unexplained atrophic kidney or size discrepancy between kidneys >1.5 cm ❑ Sudden, unexplained pulmonary edema ❑ Unexplained renal dysfunction, including individuals starting renal replacement therapy ❑ Multi-vessel CAD ❑ Unexplained CHF ❑ Refractory angina

If yes: ❑ Proceed with non-invasive imaging

Is patient allergic to contrast

If yes: ❑ Proceed with US

If no check for: ❑ Implanted devices: - Pacemakers - Defibrillators - Cochlear implants - Spinal cord stimulators ❑ Claustrophobic patient

If none of the above proceed with MRA

If yes to any of the above, proceed with CT

Inconclusive noninvasive test but with high clinical index of suspicion: ❑ Perform catheter angiography

Confirmed RAS: ❑Proceed to treatment

Algorithm based on the 2013 AHA Guidelines Recommendations for Management of Patients with PAD.

Treatment

Initiate a regimen that combines: ❑ Tight blood pressure control to <130/80 mmHg (120/75 mmHg if proteinuria is present) with: ACEI ARB CCB beta blockers ❑ Control of hyperlipidemia (LDL cholesterol <70 mg/dl) with statins ❑ Glycemic control (Hemoglobin A1c <7%) ❑ Anti platelet agents ❑ Life style modifications: Smoking cessation counseling Normalization of body weigth

Determine if the following conditions are met: ❑ Hypertension controlled on <3 drugs ❑ Stable mild/moderate renal insufficiency ❑ Advanced renal atrophy (<7.5 cm) ❑ Doppler ultrasonographic renal resistance index >80 (<7.5 cm) ❑ History or clinical evidence of cholesterol embolisation

If yes: ❑ Conservative treatment/watchful waiting

If no: ❑ Check if any of the following are present

❑ Hemodynamically significant RAS (see table above) with recurrent, unexplained CHF or sudden, unexplained pulmonary edema ❑ RAS with: - Accelerated, resistant, or malignant hypertension - Hypertension with unilateral small kidney - Hypertension with medication intolerance ❑ RAS and CRI with bilateral RAS or RAS to solitary functioning kidney ❑ RAS and unstable angina ❑ Asymptomatic bilateral or solitary viableʰ kidney with a hemodynamically significant RAS ❑ Asymptomatic unilateral hemodynamically significant RAS in a viable kidney (>7cm) ❑ RAS and CRI with unilateral RAS (2 kidneys present)

❑ If answered yes to any:

❑Renal Angioplasty/Stent

❑ Renal artery surgery

Atherosclerotic RAS

Fibromuscular dysplasia RAS

Renal stent placement is indicated for ostial atherosclerotic RAS lesions that meet the clinical criteria for intervention

Balloon angioplasty with bailout stent placement if necessary is recommended for fibromuscular dysplasia lesions

Algorithm based on the 2013 AHA Guidelines Recommendations for Management of Patients with PAD.

References

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