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.
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Other:
- Renal artery embolism
- Dissection/thrombosis
- Post-traumatic injury
- Occlusion from aortic stent graft
- External compression
- Systemic vasculitis
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
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
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
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)
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