Hypertensive Renal Disease Flashcards

1
Q

Causes of renal artery stenosis

A
  • Atherosclerotic disease (60-80%) → >55 years, prevalence increases w/ age, M=F, risk relates to burden of other CVS risk factors, ostial/proximal portion of renal artery, can be B/L, ischaemic atrophy/total occlusion common, less amenable to intervention
  • Fibromuscular dysplasia (10-20%) → non-atheromatous, non-inflammatory, +ve family history in 7%, F:M 3:1 age 35-50, mid to distal renal artery (string of beads). Risk increased w/ smoking, pregnancy. Can affect multiple vascular beds (carotids, peripheral arteries). Ischaemic atrophy/total occlusion rare. Very amenable to intervention.
  • Other:
    • Renal artery embolism
    • Dissection/thrombosis
    • Post-traumatic injury
    • Occlusion from aortic stent graft
    • External compression
    • Systemic vasculitis
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2
Q

Pathogenesis of Renovascular Hypertension

A
  • Increasing stenosis → reduction in post-stenotic blood flow and pressure → activates RAAS
    • Need approx 80% stenosis to see changes in flow/pressure and subsequent activation of renin
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3
Q

When to suspect renovascular disease/hypertension

A
  • Age of onset <30 or > 50
  • Abrupt onset hypertension
  • Acceleration of previous stable BP
  • Malignant hypertension
  • Accelerated retinopathy
  • Flash pulmonary oedema
  • AKI with ACEi
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4
Q

Diagnosis of renal artery stenosis

A
  • Renin and aldosterone levels - low sensitivity and specificity
  • Doppler ultrasound - good screening test (sensitivity 97%, specificity 81%) → no contrast/radiation, operator dependent, does over-estimate degree of stenosis, cannot accurately determine degree of stenosis in FMD
  • CT Renal angiogram → good images, can detect accessory vessels, less accuracy in advanced CKD due to calcification, may be useful for assessing stent patency c/w MRI
  • MRI Renal angiogram → Sensitivity 92-97%, specficity 73-93%, risk of gadolinium nephrogenic systemic fibrosis in CKD
  • Nuclear ACEI Scintigraphy → sensitivity >75%, specificity >90%. Administration of ACEi → reduction in efferent vascular tone, if fixed lesion in afferent vessel GFR will drop. Functional assessment not anatomic.
  • Angiography → gold standard, reserved for confirmation of diagnosis. Risks → AKI, cholesterol emboli, contrast induced nepropathy, dissection, groin haematoma
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5
Q

Medical therapy for renal artery stenosis

A
  • Blood pressure management → RAAS blockade, multimodal therapy may be required
    • RAAS blockade >90% tolerated without AKI. Also risk reduction for death
  • CVS risk factor modification
    • Lipid and diabetes
    • Smoking cessation, weight loss, salt intake reduction
    • Anti-platelets (where indicated for other vascular disease)
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6
Q

Role of angioplasty in renal artery stenosis

A
  • FMD → cure with angioplasty and stent, can re-occur w/ benefit from re-intervention also
  • Atherosclerotic → conclusions from ASTRAL & CORAL angioplasty +/- stenting no superior to medical treatment in those with mild to moderate disease w/ respect to BP control and clinical event endpoints but did not address high risk populations (advancing renal impairment, flash APO). Possible role in high risk disease.

Complications of stenting

  • Groin haematoma
  • Segmental infarction, perineprhic haematoma, renal artery thrombosis/occlusion, stent misplacement , dissections, embolisation
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