Thrombo-embolism and haemodynamic ischaemia secondary to atheromatous stenotic disease of the carotid and vertebral arteries are important causes of ischaemic stroke. In those patients with carotid stenosis the risk of stroke has been directly related to the severity of stenosis and the presence of symptoms (Inzitari et al., 2000). The average risk of stroke following a transient ischaemic attack (TIA) is about 8% in the first year and then 5% per annum, but, in patients with severe carotid stenosis, the risk even with medical treatment increases up to 28% over 2 years (NASCETC, 1991). Detection of significant carotid or vertebral artery stenosis after a TIA or stroke provides the opportunity for secondary preventive treatment of the stenosis to prevent a further stroke (see also ‘Stroke’).

Carotid endarterectomy (CEA), the surgical removal of the atheromatous plaque, was first performed fifty years ago and is, at present, still considered the gold standard in the treatment of severe symptomatic disease (Grace, 2004). The procedure usually involves the insertion of a silicon tube (shunt) directly into the opened internal and common carotid arteries. Blood then flows through the shunt from the carotid artery to the brain allowing the removal of the atherosclerotic plaque from the artery wall. A number of randomized clinical trials on selected groups of symptomatic and asymptomatic patients have indicated the benefits of CEA (NASCET, 1991; ACAS, 1995; ECST, 1998).