Carotid endarterectomy in Great Britain and Ireland

Carotid and cerebral angiography performed by cardiologists: cerebrovascular complications

The management of extracranial carotid artery disease is primarily concerned with the prevention of acute stroke. In order to understand the current risks of carotid angiography performed by interventional cardiologists, we undertook a retrospective study to determine the neurologic complications in patients who underwent selective cerebral angiography. All patients undergoing studies that were limited to diagnostic aortic arch angiography and selective four-vessel cerebral angiography in the cardiac catheterization laboratories during the past 6 years were included in this study. Hospital records were reviewed to determine any in-hospital cerebrovascular complications following carotid angiography, ranging from transient ischemic attack to major disabling stroke or death. A total of 189 consecutive patients underwent 191 diagnostic studies limited to aortic arch and four-vessel cerebral angiography in the cardiac catheterization laboratories between 1 January 1995 and 31 December 2000. Only one (0.52%) neurological complication, a minor stroke, occurred in our study population. There were no transient ischemic attacks, major strokes, or death. We have shown that experienced interventional cardiologists can perform diagnostic aortic arch and selective carotid and vertebral angiography in a cardiac catheterization laboratory with a very low complication rate. Because the risks of angiography add to those of revascularization of the carotid artery, the most highly skilled angiographer, regardless of primary specialty, should perform these studies.

Comparison of magnetic resonance angiography, duplex ultrasound, and digital subtraction angiography in assessment of extracranial internal carotid artery stenosis

The results of a prospective study comparing ultrasound, intra-arterial digital subtraction angiography, and magnetic resonance angiography in the assessment of the degree of extracranial internal carotid artery stenosis are reported in patients with symptoms of recent carotid territory ischaemia. A total of 70 patients and 137 vessels were examined by all three techniques. The results obtained by each technique were reported blind. The mean difference (SD) for the comparison of magnetic resonance angiography and digital subtraction angiography was -0.7 (14)%, for ultrasound and digital subtraction angiography 3.1 (15)%, and for magnetic resonance angiography and ultrasound -3.8 (15)%. The level of agreement was greater for the more tightly stenosed vessels. With the assumption that the results of the digital subtraction angiogram reflect the true situation, the sensitivity and specificity in the detection of > or = 30% stenoses were 93% and 82% with ultrasound and 89% and 82% with magnetic resonance angiography; for stenoses > or = 70% 93% and 92% with ultrasound and 90% and 95% with magnetic resonance angiography; and for stenoses of 70-99% 89% and 93% with ultrasound and 86% and 93% with magnetic resonance angiography. For occlusion the values were 93% and 99% with ultrasound and 80% and 99% with magnetic resonance angiography. Increased sensitivity and specificity were obtained when analysis was confined to those vessels in which ultrasound and magnetic resonance angiography were in agreement over classification. It is thus possible to accurately categorize the degree of stenosis of the extracranial internal carotid artery from a combination of ultrasound and magnetic resonance angiography. The adoption of this combination for the investigation of patients before carotid endarterectomy removes the risk associated with conventional angiography and represents an important advance in the management of carotid stenosis.

Carotid endarterectomy in Great Britain and Ireland: practice between 1984 and 1992

Of 356 questionnaires on carotid endarterectomy sent to all vascular surgeons in Great Britain and Ireland likely to undertake this procedure, 326 (92 per cent) were returned. Of those who replied 131 (40 per cent) performed at least one carotid endarterectomy in 1992; 57 (44 per cent) of these carried out ten or fewer operations and 74 (56 per cent) more than ten. The 131 surgeons were collectively responsible for 2628 operations in 1992, twice as many as were undertaken in either 1984 or 1989, years for which similar survey data are available. This sharp rise in the number of operations was accounted for by increased activity on the part of experienced operators, rather than any rise in the number of 'occasional' carotid surgeons. In 1992, although the neurologist remained a major source of patient referral, general practitioners (and others) were also referring patients in large numbers direct to the vascular surgeon; this represents a change in practice compared with previous years. Many of the technical aspects surrounding carotid endarterectomy remained unchanged over the years surveyed (1984, 1989, 1992) but by 1992 duplex scanning, intra-arterial (but not intravenous) digital subtraction angiography and transcranial Doppler ultrasonography had become established as clinically useful techniques.

Complications of cerebral angiography in patients with symptomatic carotid territory ischaemia screened by carotid ultrasound

After nearly 40 years, carotid endarterectomy has been shown to be of benefit to patients with symptomatic carotid territory ischaemia and greater than 70% stenosis of the relevant internal carotid artery. Cerebral angiography is performed before surgery and is not without risk. These risks must be added to those of surgery before recommending the procedure to patients. The study evaluated the local, systemic and neurological complications following digital subtraction angiography with selective catheterisation of the carotid arteries in 200 patients presenting to a cerebrovascular clinic for assessment of cerebral ischaemia. All patients had carotid ultrasound screening before angiography to screen out those with normal arteries or mild disease (less than 30% stenosis of symptomatic internal carotid artery). Complications occurred in 28 patients. There were six (3%) local, two (1%) systemic and 20 (10%) neurological complications. Seventeen neurological complications occurred within 24 hours and there were three late complications (24-72 hours). Neurological complications occurred more frequently when angiography was performed by a trainee rather than a consultant neuroradiologist (p < 0.01). The neurological complications were transient (resolved within 24 hours) in 10/200 (5%), reversible (resolved within seven days) in two (1%) and permanent in 8/200 (4%). Two patients died after a stroke and two other patients suffered a disabling stroke. At 24 hours post angiography the permanent (persisting beyond seven days) neurological complication rate was 2.5%. The incidence of total neurological complications and post angiographic strokes was higher in patients with greater than 90% stenosis of the symptomatic internal carotid artery (p < 0.001). The increased use of non-invasive Doppler duplex screening will reduced the absolute number of patients put at risk of angiography, yet the rate of post angiographic complications is likely to increase as patients with severe stenosis of the symptomatic internal carotid artery are probably most at risk of complications and have most to gain from carotid endarterectomy.

Carotid endarterectomy: recommendations for management of transient ischaemic attack and ischaemic stroke. Association of British Neurologists

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Cost-effective investigation of patients with suspected transient ischaemic attacks

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Carotid endarterectomy in Great Britain and Ireland: trends and current practice

Of 309 questionnaires on carotid endarterectomy sent to all surgeons in Great Britain and Ireland who might use this technique, 298 (96 per cent) were returned. In all, 110 (37 per cent) of 298 surgeons performed at least one carotid endarterectomy in 1989; 67 performed less than 10 and 43 greater than 10. In total, these 110 surgeons performed 1417 operations in 1989, a situation that has changed little over 5 years since the previous survey. Transient ischaemic attack and minor stroke remain the main indications for carotid endarterectomy; the operation was hardly ever performed for asymptomatic stenosis. By 1989 almost all surgeons initially assessed prospective patients using a technique less invasive than conventional angiography; duplex scanning was used 'always' or 'sometimes' by 70 per cent of surgeons. While 72 per cent of surgeons in 1984 'always' required conventional angiograms before operation, by 1989 only 21 per cent did so, most now relying on less invasive techniques. During operation there was an increasing use of shunts, carotid sinus nerve blockade and patch closure of the arteriotomy. The overall number of carotid endarterectomies performed annually in Great Britain and Ireland has remained steady over the past 5 years and is relatively low for a population of 60 millions. An increase in the number of surgeons performing the operation is almost entirely accounted for by an increase in those performing less than 10 carotid endarterectomies per year.

Neurosurgical experience with carotid endarterectomy: a 12-year study

In the 13-year period from 1975 to 1988, 91 carotid endarterectomies were performed on 83 patients in a neurosurgical unit. Sixty-seven of these patients had continued to have symptoms after the best medical treatment. Seventy-one presented with transient ischaemic attacks (TIAs), nine with TIA and minor completed stroke (MCS), and three with MCS alone. Follow-up ranged from 8 months to 12 years with a mean of 5.5 years. Within the follow-up period, including operative complications, four deaths of cerebral origin (4.8%) and three major cerebral events (3.6%) occurred--an annual stroke morbidity and mortality rate of less than 1.5%, which compares favourably with a minimum stroke risk of 5% per annum for the first 3 years following a TIA and 3% for subsequent years. The annual stroke and/or vascular death rate including myocardial infarction was 3.5% compared to an expected stroke and/or vascular death rate of 7.4%. It appears that carotid endarterectomy is a useful adjunct to medical therapy. Myocardial ischaemia is the major cause of death in the follow-up period in this group of patients. It is suggested that patients with TIAs and MCS should be investigated, and those who do not respond to medical therapy should be identified for carotid endarterectomy.

Complications of cerebral angiography for patients with mild carotid territory ischaemia being considered for carotid endarterectomy

It is essential to image the carotid bifurcation adequately in patients with symptomatic carotid territory ischaemia if they are being considered for carotid endarterectomy. Optimal resolution is achieved by selective intraarterial contrast angiography which is an invasive procedure carrying some risk. The overall risk-benefit of carotid endarterectomy is currently being investigated in several large randomised trials in Europe and North America. Because cerebral angiography is a prerequisite for carotid endarterectomy, the risks of cerebral angiography will need to be added to those of surgery when considering whether carotid endarterectomy is effective in the management of these patients. This study evaluated prospectively 382 patients with symptomatically mild carotid ischaemia who had cerebral angiography to visualise a potentially resectable lesion at the carotid bifurcation. Complications followed 14 cerebral angiograms in 13 patients (3.4%); two complications were local (0.5%), two systemic (0.5%) and 10 were neurological (2.6%). The neurological complications were transient (TIA 1, generalised seizure 1) in two patients (0.5%), reversible (stroke) in three (0.8%) and permanent (stroke) in five patients (1.3%). There were no deaths. The significant risk factors for post angiographic stroke were (1) stroke before angiography compared with transient ischaemic attacks of the eye or brain and (2) the presence of greater than or equal to 50% diameter stenosis of the symptomatic internal carotid artery; unfortunately it may be the latter patients who are most at risk of stroke as part of the natural history of their disease and therefore most in need of prophylactic carotid endarterectomy (which requires cerebral angiography). The absolute risk of post-angiographic stroke of patients for cerebral angiography using clinical evaluation and Duplex carotid ultrasound screening.

Cerebral angiographic risk in mild cerebrovascular disease

We review the eight prospective and seven retrospective studies from which it is possible to derive the complication rate of conventional cerebral angiography for patients with mild ischemic cerebrovascular disease who are potential candidates for carotid endarterectomy. Three studies of intravenous and one of intra-arterial digital subtraction angiography are also examined. An overview of the results suggests that the risk of a neurological complication (TIA or stroke) is about 4% and that a permanent neurological deficit (disabling stroke) occurs in about 1%. The mortality rate is very low (less than 0.1%). Systemic complications are not infrequent, particularly with intravenous digital subtraction angiography. The complication rate of cerebral angiography must be considered when evaluating the risks of carotid endarterectomy in patients with ischemic cerebrovascular disease.

Cerebral angiography for cerebrovascular disease: the risks

Cerebral angiography is still suggested as a first line investigation for patients with putative transient ischaemic attacks (TIA) and it is considered by most surgeons as a necessary prelude to carotid endarterectomy. That conventional cerebral angiography involves risk is well known, although the magnitude of this risk is not. Prospective studies of cerebral complications from this technique, published over the last decade, have been analysed to show that the major stroke rate after conventional cerebral angiography for patients with TIAs is likely to be about 2.4 per cent. This must be taken into account if the true morbidity of carotid endarterectomy is to be appreciated (assuming conventional angiograms have been used). Furthermore, since many sufferers are assessed by angiography but not submitted to surgery, a policy of conventional angiography for patients with TIAs puts a far greater number at risk than that actually having carotid endarterectomy.