Doppler ultrasound assessment of the internal carotid artery following carotid endarterectomy.

Abstract

SUMMARY Doppler-shifted ultrasound with spectral analysis was used to assess the internal carotid arteries of 48 patients who had undergone carotid endarterectomy (58 carotid endarterectomies). Three patients died in the immediate post-operative period, therefore 45 patients, who represented 54 endarterec tomies, were assessed for up to six years following surgery (mean -thirty-four months).Ultrasound tests demonstrated total occlusion of the internal carotid artery in 7 patients within the first post-operative week. Sonagrams from the supraorbital and common carotid arteries exhibit two peaks during cardiac systole (A and B). The post-operative A/B ratios were abnormal in 24 instances and these were associated with symptoms in seven. Of these 24, 7 developed severe disease in the internal carotid artery during the six year follow-up period; five were associated with symptoms. Post-operative A/B ratios were normal in 23 instances, 19 of which remained normal at follow-up. None of these nineteen developed symptoms.Only patients with abnormal post-operative A/B ratios subsequently developed severe occlusive disease in the internal carotid artery during the follow-up assessment.Thirty-eight patients underwent unilateral carotid endarterectomy, eight of whom had severe internal carotid artery disease at the contralateral bifurcation at the time of carotid endarterectomy. A further four patients developed severe occlusive disease in the contralateral internal carotid artery during the follow-up period, one of whom was symptomatic. Stroke Vol 14, No 6, 1983THE BENEFIT OF CAROTID ENDARTERECTOMY has usually been assessed clinically by the prevention of further symptoms. 12It is only relatively recently that readily repeatable methods for objective follow-up assessment of the patency of carotid arteries have been available which have no significant complications. Ca rotid angiography is the standard method for assessing carotid artery disease but it is not entirely satisfactory since it may miss ulceration or lesions present in a different plane to that of the angiogram. 3,4 It is also associated with complications 5 ' 6 and therefore is not routinely used to assess the patency of the internal carotid artery in asymptomatic patients following ca rotid endarterectomy. 7Angiography performed soon after carotid surgery can provide unreliable information, which may be due to tissue fragmentation and oedema of the vessel wall. 8Postoperative angiograms were performed by Schultz and his colleagues 9 who reported that of eleven internal carotid arteries shown to have irregular walls at this time, four were found to be smooth on angiograms performed after a further six months. Lougheed et al 10 also reported a patient in whom a carotid angiogram, which was not performed until six months after carotid endarterectomy, showed the arterial wall to be irregu lar, whilst an angiogram performed more than two years later demonstrated a smooth wall.Non-invasive tests have been developed in recent years to avoid the risks of angiography a...