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Background: Our report summarizes and compares the characteristics of six prospective, multicenter, randomized clinical trials of carotid endarterectomy underway in North America and Europe., Summary of Review: Three trials are designed to evaluate the safety and efficacy of endarterectomy in patients with asymptomatic carotid artery stenosis. The other three trials enroll patients who have had transient ischemic attacks or a minor cerebral infarction in the distribution of the randomized artery. Considered together, these six clinical trials span the range of candidates for carotid endarterectomy. The inclusion and exclusion criteria, methodology, and statistical considerations of each study are detailed in tables., Conclusions: The results from these trials will be helpful in resolving some of the questions surrounding endarterectomy, provided the similarities and differences in the study designs are considered when interpreting the results.

We have developed a scoring system to quantify extent of extracranial carotid artery atherosclerosis using real-time ultrasound (B-mode). To evaluate repeatability of this scoring system we correlated repeat scores obtained within a short interval of one another (6 months) in 52 individuals. We compared repeatability of extent measurements with repeatability of a measure of severity (single most severe lesion). Correlations between first and second studies for severity were weak (r2 = 0.20) but significant (p less than 0.001). Extent scores correlated much better (r2 = 0.77, p less than 0.001). In another group of 22 patients we found that the extent of atherosclerosis decreased following endarterectomy. We used this method to determine changes in extent of carotid atherosclerosis with age in two sets of individuals. One consisted of a cohort of 22 patients who underwent repeat B-mode studies separated by 1 1/2-3 years. This cohort demonstrated an increase in carotid score with age (p less than 0.05). In a second group of volunteers undergoing cardiac catheterization and B-mode evaluation of the carotid system, carotid scores could be compared in individuals with age differences that averaged 15 years. Extent of carotid atherosclerosis was significantly greater in older individuals (p less than 0.01) and differences in extent with age were exaggerated in patients with coronary disease compared to coronary disease free controls.

We polled 582 physicians to determine what their approach would be to management of an asymptomatic murmur at the carotid bifurcation and to carotid-distribution transient ischemic attack. We discovered a great disparity in attitudes attributable to location and type of practice. However, there was no difference attributable to age, and few differences were found with respect to measures of the physician's awareness of his own health. Physicians' attitudes and practices do not necessarily parallel scientific literature or recommendations of experts in the field.

Continuous-wave (CW) Doppler ultrasound imaging for prediction of arteriogrphic abnormality at the carotid bifurcation was carried out in 195 arteries of 105 patients. The Doppler method had no predictive value when compared to angiographic findings in arteries classified as 0-50% stenosis by Doppler. In 50-75% stenosis by arteriography Doppler accuracy was 52%. With stenosis of 76-99% Doppler imaging correlated with 71% reliability. When an arteriogram was compared with Doppler imaging the latter gave a "false negative" reading in 56% and "false positive" readings in 19%. We conclude that Doppler ultrasound evaluation provides important information regarding the state of the carotid bifurcation, which supplements the bedside evaluation, but it does not substitute for arteriography.

Cerebral angiographic findings of 32 Japanese patients with carotid system TIA's were compared with those of an equal number of age and sex matched American Caucasians. The end points included irregularity, ulceration, stenosis or occlusion of the carotid artery appropriate to the side of TIA. Atherosclerotic changes were found in 27 patients (84.4%) of the Japanese and 30 patients (93.7%) of the American patients. Mild lesions (49% stenosis and below) were similar in either frequency of topography between both groups; namely 25 intracranial and 17 extracranial lesions in Japanese as well as 29 intracranial and 10 extracranial in Caucasian patients. There was, however, an extra-intracranial difference in severe lesions (50% stenosis and above) between American Caucasian and Japanese patients; 10 of 12 severe lesions in Japanese were located intracranially, while 17 of 20 severe lesions present in the American group occurred in the extracranial portion of the internal or common carotid arteries.

The plethora of recent articles regarding carotid endarterectomy has tended to confuse rather than clarify its indications, efficacy, and acceptability. The National Institutes of Health has recently funded two large multicenter controlled clinical trials, one including asymptomatic persons with carotid stenoses, and the other, patients having transient ischemic episodes or minor strokes. Eight academic professors of neurology (four), neurosurgery (two), and vascular surgery (two) with a long and abiding interest in cerebrovascular disease prepared a statement delineating acceptable levels of mortality and morbidity from this procedure. These might serve as guidelines until the large trials have been completed.

One hundred patients with asymptomatic carotid bruit or transient ischemic attack (TIA) underwent continuous-wave Doppler (CWD) and real time ultrasound (RTU) testing of their cervical carotid arteries. After ultrasonic studies, 51 patients also underwent bilateral carotid angiography. There was 95% agreement between CWD and angiography for the diagnosis of a significant (greater than 50%) stenosis. The RTU diagnosis of a normal or occluded vessel was correct in 100% of cases. Seven plaques appreciated on RTU may not have been large enough for detection by angiography. In this small series, ulceration confirmed pathologically was more reliably predicted by RTU than by cerebral angiography. Significant ipsilateral carotid plaques occurred more often in patients with amaurosis fugax than in patients with hemispheric TIAs. Ipsilateral plaque ulceration occurred in 50% of symptomatic carotid bruits, but in only 10% of asymptomatic carotid bruits. Plasma concentrations of total cholesterol were significantly higher in TIA patients with carotid stenosis than in controls.

A rare type of fibromuscular dysplasia of the common carotid artery, in the form of a septum, was observed in a patient suffering from recurrent cerebral infarctions. Angiography demonstrated growth of the lesion and documented the presence of an intraluminal thrombus attached to it. Comparison with reported cases of the more common "string of beads" lesion of fibromuscular dysplasia suggests that the risk for development of ischemic neurological problems is higher for this type of fibromuscular lesion. Surgical correction is recommended, especially for symptomatic patients.

The effects of irradiation on blood vessels supplying the brain are reviewed. Short-term and long-term effects on large arteries result in an atheroscleroticlike disorder. The response may have a latency up to 20 years before the onset of symptoms and signs. This delay is probably related to the diameter of the irradiated artery; the interval is longer for larger arteries. However, it is possible that the apparent injury to the large arteries is in fact due to occlusion of the vasa vasorum because the microvasculature is especially vulnerable to radiation damage.