Renal artery stenosis

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Renal artery stenosis
Renal papilla
  • 17. Renal column
    • SpecialtyNephrology
    Risk factorsSmoking, High blood pressure[1]
    Diagnostic methodCaptopril challenge test, Doppler ultrasound[2][3]
    TreatmentACE inhibitors[1]

    Renal artery stenosis (RAS) is the

    blood flow to the target kidney, resulting in renovascular hypertension – a secondary type of high blood pressure. Possible complications of renal artery stenosis are chronic kidney disease and coronary artery disease.[1]

    Signs and symptoms

    Most cases of renal artery stenosis are asymptomatic, and the main problem is high blood pressure that cannot be controlled with medication.

    flash pulmonary edema.[5]

    Cause

    Renal artery stenosis is most often caused by atherosclerosis which causes the renal arteries to harden and narrow due to the build-up of plaque. This is known as atherosclerotic renovascular disease, which accounts for about 90% of cases.[6] This narrowing of renal arteries due to plaque build-up leads to higher blood pressure within the artery and decreased blood flow to the kidney. This decreased blood flow leads to decreased blood pressure in the kidney, which leads to the activation of the Renin-Angiotensin-Aldosterone (RAA) system. Juxtaglomerular cells secrete renin, which converts angiotensinogen to angiotensin I, which is then converted to angiotensin II by angiotensin converting enzyme (ACE). Angiotensin II then acts on the adrenal cortex to increase secretion of the hormone aldosterone. Aldosterone causes sodium and water retention, leading to an increase in blood volume and blood pressure. Therefore, people with RAS have chronic high blood pressure because their RAA system is hyperactivated.[7]

    Pathophysiology

    The pathophysiology of renal artery stenosis leads to changes in the structure of the kidney that are most noticeable in the

    tubular tissue.[8] If the stenosis is longstanding and severe, the glomerular filtration rate in the affected kidneys never recovers and (prerenal) kidney failure is the result.[medical citation needed
    ]

    Changes include:[8]

    • Fibrosis
    • Tubular cell
      size (decrease)
    • Thickening of
      Bowman capsule
    • Tubulosclerosis
    • Glomerular capillary tuft (atrophy)

    Diagnosis

    Assessment of Kidneys with Renal Artery Stenosis taken by Magnetic Resonance Angiography.

    The diagnosis of renal artery stenosis can use many techniques to determine if the condition is present, a clinical prediction rule is available to guide diagnosis.[9]

    Among the diagnostic techniques are:

    The specific criteria for renal artery stenosis on Doppler are an acceleration time of greater than 70 milliseconds, an acceleration index of less than 300 cm/sec² and a velocity ratio of the renal artery to aorta of greater than 3.5.[2]

    Treatment

    A diuretic (Hydrochlorothiazide)

    Atherosclerotic renal artery stenosis

    It is initially treated with medications, including

    minimally-invasive angioplasty with or without stenting. It is unclear if this approach yields better results than the use of medications alone.[15] It is a relatively safe procedure.[15] If all else fails and the kidney is thought to be worsening hypertension and revascularization with angioplasty or surgery does not work, then surgical removal of the affected kidney (nephrectomy) may significantly improve high blood pressure.[16]

    Fibromuscular dysplasia

    Angioplasty alone is preferred in fibromuscular dysplasia, with stenting reserved for unsuccessful angioplasty or complications such as dissection.[17]

    See also

    References

    1. ^ a b c "Renal Artery Stenosis". National Institute of Diabetes and Digestive and Kidney Diseases. Retrieved 2015-08-17.
    2. ^
      PMID 23397022
      .
    3. ^
      ISBN 9789812560735
      .
    4. ^ MedlinePlus Encyclopedia: Renovascular hypertension
    5. PMID 21406441
      .
    6. PMID 29056991
      .
    7. S2CID 232311595
      .
    8. ^ a b c Renal Artery Stenosis at eMedicine
    9. ISBN 9780387772448
      .
    10. PMID 24135303
      .
    11. ISBN 9780729541473
      .
    12. PMID 24591488
      .
    13. ISBN 978-1405183239
      .
    14. PMID 22085467
      .
    15. ^
      PMID 25478936
      .
    16. ISBN 9781444312737
      .
    17. PMID 24649423
      .

    Further reading

    External links

    Scholia has a topic profile for Renal artery stenosis.
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