What is Carotid Artery Stenting (CAS)
The carotid arteries in the neck supply blood to the brain. When they become narrowed (stenosed) due to atherosclerotic plaque build-up, fragments of this plaque can break off and travel to the brain, causing a stroke or TIA (mini-stroke). Carotid artery stenting involves placing a stent across the narrowed segment to restore full blood flow and prevent these embolic events.
CAS is an alternative to carotid endarterectomy (surgical removal of plaque) and is particularly favoured for patients who are high surgical risk, have had prior neck surgery or radiation, or have a stenosis in a location difficult to access surgically.
Who Needs Carotid Stenting?
Carotid stenting is recommended for patients with significant narrowing of the carotid arteries, particularly those with symptomatic carotid stenosis greater than 50% following a transient ischaemic attack (TIA) or minor stroke. It is also considered in asymptomatic patients with high-grade stenosis, typically greater than 70–80%, when they are suitable candidates for intervention. This procedure is especially beneficial for individuals at high surgical risk, including those with severe cardiac disease, a history of prior neck surgery, or previous radiation therapy. Additionally, carotid stenting is indicated in cases of restenosis following carotid endarterectomy and in patients with carotid artery narrowing located in areas that are difficult to access surgically, such as high bifurcation or intracranial extension.
How CAS is Performed
- Under local anaesthesia and mild sedation, a catheter is inserted through the femoral artery at the groin
- An embolic protection device (filter) is deployed beyond the stenosis to catch any dislodged plaque particles during the procedure
- The narrowed segment is pre-dilated with a small balloon (angioplasty)
- A self-expanding stent is deployed across the stenosis and post-dilated to ensure full expansion
- The embolic protection filter is retrieved, and a final angiogram confirms restored blood flow
Renal Artery Stenting
The renal (kidney) arteries supply blood to the kidneys and regulate blood pressure through the renin-angiotensin system. When these arteries are significantly narrowed (renal artery stenosis), the affected kidney releases excess renin, causing severe, often medication-resistant hypertension. Over time this can damage both kidneys, leading to chronic kidney disease.
Renal artery stenting involves placing a balloon-expandable stent across the narrowed segment, restoring blood flow to the kidney, often resulting in better blood pressure control and preservation of kidney function.
Who Needs Renal Artery Stenting?
- Resistant hypertension (uncontrolled on 3 or more antihypertensive medications)
- Renal artery stenosis >70% on CT/MR angiography
- Flash pulmonary oedema (sudden lung fluid accumulation) with bilateral renal artery stenosis
- Progressive reduction in kidney function (GFR decline) attributable to stenosis
- Fibromuscular dysplasia (FMD) causing renal artery stenosis, especially in young women
How Renal Artery Stenting is Performed
- Access is typically obtained through the femoral artery under local anaesthesia
- A guide catheter is positioned at the origin of the affected renal artery
- Angiography confirms the stenosis location and severity
- A balloon-expandable stent is deployed precisely at the stenosis, which is then inflated to embed the stent into the artery wall
- Completion angiography confirms optimal result with no significant residual stenosis
