Related Subjects: |Hypertension |Hypertension in Pregnancy |Acute Heart Failure |Chronic Heart Failure

MR angiography is probably the investigation of choice nowadays for suspected RAS. ACEI can cause worsening renal function and AKI in those with renal artery stenosis

ℹ️ About

• Potentially treatable cause of hypertension
• Suspect in older patients with atheroma
• Suspect in younger patients with hypertensions

Causes

• Fibromuscular dysplasia (20-40%): younger often female. Beaded appearance.
• Atherosclerosis: older patients. The lesion usually ostial within 1 cm of the proximal renal artery. Often have missing pulses, bruits and atheroma

Clues to diagnose RAS - Suspected renal artery stenosis if there is a greater than 25% reduction in eGFR within 3 months of starting (or increasing the dose of) a renin-angiotensin system antagonist, refractory hypertension, pulmonary oedema, and/or a renal artery bruit.

• Worsening renal function with ACEI
• Disparity on renal size on USS >1.5 cm (Ischaemic nephropathy)
• Flash pulmonary oedema
• Neurofibromatosis I (also get phaeochromocytomas)
• Renal bruit
• Intermittent claudication suggesting coexisting atherosclerosis + hypertension
• Proteinuria

Tests

• Captopril enhanced radionuclide renal scan: shows reduced uptake on the affected side which may be exacerbated by Aspirin or captopril
• MR Angiography with gadolinium enhancement shows a string of beads in Fibromuscular dysplasia and focal narrowing with atherosclerosis
• Spiral CTA with contrast less expensive than MRA
• Duplex doppler scan can assist renal artery flow velocity
• Intra-arterial angiography: the gold standard – should be carried out by experienced radiologists with minimal contrast load.

Indications for interventions

• Stenosis>75%
• Flash pulmonary oedema
• Resistant hypertension
• Affecting solitary kidney

💊 Management

• Treat Pulmonary oedema. Avoid ACEI/AT2 blockers. Use Furosemide, Nitrates. Also consider low-dose dopamine for its natriuretic effect if no response to initial therapy.
• Best Medical - Aspirin, statins, BP meds, Calcium channel blockers, Diuretics to optimise blood pressure and atheroma
• Transluminal Angioplasty +/- stents but risks appear higher in those with Fibromuscular dysplasia
• Surgical resection of a stenosed portion of the artery
• Nephrectomy may be required
• Blood pressure improves but rarely returns to normal after treatment for atherosclerotic RAS. A lot depends on patient selection as at post mortem studies some degree of RAS is often seen in those with atherosclerosis and hypertension but may not be causative.

Cases — Renal Artery Stenosis / Renovascular Disease

• Case 1 — Resistant hypertension 🩺: A 58-year-old man with long-standing hypertension remains uncontrolled despite triple therapy (ACE inhibitor, calcium-channel blocker, thiazide). Exam: abdominal bruit. Bloods: creatinine 120 µmol/L. Renal Doppler ultrasound: reduced flow in right renal artery. Diagnosis: atherosclerotic renal artery stenosis. Managed with aggressive risk factor control, antihypertensives, and consideration of stenting if progressive.
• Case 2 — Flash pulmonary oedema 🌊: A 72-year-old woman presents with recurrent sudden pulmonary oedema and uncontrolled blood pressure. Exam: elevated JVP, bilateral basal crackles. Creatinine rises after starting ACE inhibitor. MR angiography: bilateral renal artery stenosis. Diagnosis: bilateral RVD with recurrent flash pulmonary oedema. Managed with cautious antihypertensives and endovascular intervention.
• Case 3 — Fibromuscular dysplasia (young woman) 👩: A 34-year-old woman presents with severe hypertension (BP 200/110) and headache. She has no vascular risk factors. Exam: bruit over epigastrium. CT angiography: “string of beads” appearance in renal arteries. Diagnosis: fibromuscular dysplasia causing renal artery stenosis. Managed with percutaneous angioplasty, which is often curative.

Teaching Point 🩺: Renovascular disease should be suspected in resistant hypertension, flash pulmonary oedema, deteriorating renal function on ACEi/ARB, or abdominal bruits. Causes include atherosclerosis (elderly, male, vascular risk factors) and fibromuscular dysplasia (younger women).