CAROTID ARTERY DISEASE
Stroke is a major cause of morbidity and death in Western Society. Fatty plaque (atherosclerosis) in the carotid arteries, can cause stroke. Removal of this plaque by surgical means can in some cases prevent stroke.
The carotid arteries provide a large proportion of the blood supply to the brain. A build-up of atheroma in the carotid artery can impair blood flow to the brain in two ways. Small clots can form in the plaque, break off and travel to the brain, thereby causing a minor or major stroke. Alternatively, it can reduce the blood flow to the brain thereby causing a stroke. It is therefore vital to identify those patients at risk of stroke due to carotid plaque, and to treat them before a major stroke occurs.
The development of atheroma is linked to certain risk factors, such as a family history of vascular disease, smoking, high blood pressure, high cholesterol, diabetes and obesity.
How is carotid disease identified?
It is important to make a distinction between those with no symptoms (asymptomatic carotid stenosis), and those with symptoms (symptomatic stenosis), as this has implications regarding management.
In patients with asymptomatic disease, the carotid plaque may be a chance finding. It may be suspected by the presence of a noise or “bruit” heard with the stethoscope. Duplex or ultrasound scanning of the carotid artery may verify the presence of a narrowing in the carotid artery.
In patients with symptomatic disease, the symptoms may be transient, lasting less than 24 hours, and are therefore referred to as transient ischaemic attack (TIA) or mini-stroke. These symptoms include numbness limited to one side of the body, affecting an arm or leg, weakness or paralysis affecting one side of the body, difficulty speaking or understanding speech, or visual disturbance, affecting one or both eyes.
Neurological symptoms, lasting in excess of 24 hours, reflect permanent damage to the brain due to a stroke.
The diagnosis is usually confirmed with an ultrasound or duplex scan. This is a non-invasive scan, easy to perform, does not involve any radiation and is reliable. (see picture)
In order to obtain more information regarding the characteristics of the plaque and the rest of the carotid artery, a CT angiogram or catheter angiogram may sometimes be required.
How is the carotid plaque treated
Carotid Endarterectomy (see operations performed)
This operation is performed in an operating suite, under general anaesthesia. The carotid artery is exposed in the neck, the artery clamped, opened and the plaque removed from the artery. The artery is then closed, either directly or using a patch, thus restoring normal flow to that side of the brain. A shunt may be used to maintain flow to the brain for the duration of the period of clamping.
It is important to bear in mind that the operation is performed to prevent a stroke in patients deemed to be at risk. The operation itself however does carries a small risk of stroke (less that 2%).
Carotid Stent (see operations performed)
In some cases, the carotid plaque can be treated with a stent. This procedure is performed in the catheter laboratory under X-ray guidance. Access to the carotid arteries is gained by puncturing the femoral artery in the groin, from where the stent is delivered. This technique has the advantage that it can performed under local anaesthesia and avoids the need for a surgical incision.
However, carotid stenting is often deemed to be more hazardous that the surgical approach, which remains the procedure of choice in most cases.