PubMed Health⌕ Search

Biomedical subjects

G G Ferguson

Publications and source records attributed to G G Ferguson.

At least 19 recordsLinked to original sources
PubMed1997

Guidelines for the use of carotid endarterectomy: current recommendations from the Canadian Neurosurgical Society.

OBJECTIVE: To develop guidelines on the suitability of patients for carotid endarterectomy (CEA). OPTIONS: For atherosclerotic carotid stenosis that has resulted in retinal or cerebral ischemia: antiplatelet drugs or CEA. For asymptomatic carotid stenosis: CEA or no surgery. OUTCOMES: Risk of stroke and death. EVIDENCE: Trials comparing CEA with nonsurgical management of carotid stenosis. VALUES: Greatest weight was given to findings that were highly significant both statistically and clinically. BENEFITS, HARMS AND COSTS: Benefit: reduction in the risk of stroke. Major harms: iatrogenic stroke, cardiac complications and death secondary to surgical manipulations of the artery or the systemic stress of surgery. Costs were not considered. RECOMMENDATIONS: CEA is clearly recommended for patients with surgically accessible internal carotid artery (ICA) stenoses equal to or greater than 70% of the more distal, normal ICA lumen diameter, providing: (1) the stenosis is symptomatic, causing transient ischemic attacks or nondisabling stroke (including retinal infarction); (2) there is no worse distal, ipsilateral, carotid distribution arterial disease; (3) the patient is in stable medical condition; and (4) the rates of major surgical complications (stroke and death) among patients of the treating surgeon are less than 6%. Surgery is not recommended for asymptomatic stenoses of less than 60%. Symptomatic stenoses of less than 70% and asymptomatic stenoses of greater than 60% are uncertain indications. For these indications, consideration should be given to (1) patient presentation, age and medical condition; (2) plaque characteristics such as degree of narrowing, the presence of ulceration and any documented worsening of the plaque over time; (3) other cerebral arterial stenoses or occlusions, or cerebral infarcts identified through neuroimaging; and (4) surgical complication rates at the institution. CEA should not be considered for asymptomatic stenoses unless the combined stroke and death rate among patients of the surgeon is less than 3%. VALIDATION: These guidelines generally agree with position statements prepared by other organizations in recent years, and with a January 1995 consensus statement by a group of experts assembled by the American Heart Association.

Canada↗
PubMed1995

Long-term prognosis and effect of endarterectomy in patients with symptomatic severe carotid stenosis and contralateral carotid stenosis or occlusion: results from NASCET. North American Symptomatic Carotid Endarterectomy Trial (NASCET) Group.

The purpose of this study was to examine how the prognosis of patients who presented with a recent ischemic event referable to a 70% to 99% stenosis of one carotid artery (ipsilateral) was altered by stenosis and occlusion of the contralateral carotid artery. The benefit of performing carotid endarterectomy on the recently symptomatic artery, in the presence of contralateral artery disease, was also examined. A total of 659 patients were grouped into one of three categories according to the extent of stenosis in the contralateral carotid artery: less than 70% (559 patients), 70% to 99% (57 patients), and occlusion (43 patients). Strokes that occurred during the follow-up period were designated as ipsilateral if they arose from the same carotid artery as the symptom for which the patient had been entered into the study. Medically treated patients with an occluded contralateral artery were more than twice as likely to have had an ipsilateral stroke at 2 years than patients with either severe (hazard ratio: 2.36; 95% confidence interval (CI): 1.00-5.62) or mild-to-moderate (hazard ratio: 2.65; 95% CI: 1.43-4.90) contralateral artery stenosis. The perioperative risk of stroke and death was higher in patients with an occluded contralateral artery (4.0% risk) or mild-to-moderate (5.1% risk) contralateral stenosis. Regression analyses indicated that the results were not affected by other risk factors. An occluded contralateral carotid artery significantly increased the risk of stroke associated with a severely stenosed ipsilateral carotid artery. Despite higher perioperative morbidity in the presence of an occluded contralateral artery, the longer-term outlook for patients who had endarterectomy performed on the recently symptomatic, severely stenosed ipsilateral carotid artery was considerably better than for medically treated patients.

Aged↗
PubMed1995

Current status of the prospective, randomized trials of symptomatic carotid bifurcation disease.

Three contemporary trials that are studying patients who have symptomatic carotid disease have proven beyond doubt that CE is extremely beneficial in reducing the risk of future stroke in patients with high-grade stenosis (greater than 70%). The relative risk of major stroke is reduced by at least 80% at 2 years of follow-up. That such a remarkably positive result for surgery was not predicted is a consequence of the unanticipated malignant natural history of TIAs and minor stroke in severe carotid disease. Previous epidemiological studies had underestimated the risk of future stroke by almost threefold. The current studies also highlight the remarkable power of prospective clinical trials to evaluate the effectiveness of a surgical procedure. In the case of NASCET, only 659 patients were required to prove the benefit of CE, whereas, innumerable previous anecdotal cases had failed to provide a convincing answer. However it must be remembered that the benefit from CE is dependent on a low rate of perioperative morbidity and mortality, a strict measure of the degree of stenosis on angiography, recency of ischemic events, and unequivocal carotid symptoms. The ongoing study of patients with moderate degrees of carotid stenosis holds the promise that in the very near future precise guidelines, which have been properly evaluated by careful scientific scrutiny,, will be available to guide surgeons in the proper management of all patients who present with symptomatic carotid disease.

Carotid Artery Diseases↗
PubMed1994

Prevention of functional impairment by endarterectomy for symptomatic high-grade carotid stenosis. North American Symptomatic Carotid Endarterectomy Trial Collaborators.

OBJECTIVE: To determine whether carotid endarterectomy prevents deterioration of functional status among patients with transient ischemic attacks or nondisabling strokes and ipsilateral carotid stenosis of 70% to 99%. DESIGN: Multicentered randomized controlled trial with an average 18-month follow-up. SETTING: Fifty clinical centers in North America. PATIENTS: A total of 659 patients presenting with recent transient attacks of nondisabling stroke and ipsilateral atherosclerotic carotid stenosis of 70% to 99% were included. Patients were stable neurologically at the time of entry. No patient was lost to follow-up. INTERVENTION: Vascular surgeons and neurosurgeons were prescreened for low perioperative complication rates. Patients were randomly allocated to carotid endarterectomy plus continuing medical care (n = 328) or medical care alone (n = 331), including antiplatelet therapy. MAIN OUTCOME MEASURES: All patients were assessed by neurologists for the occurrence of stroke and functional status at scheduled intervals after entry. RESULTS: In addition to a previously reported risk reduction for ipsilateral stroke for patients assigned to carotid endarterectomy, there was an absolute risk reduction (and relative risk reduction [RRR]) for functional status impairment of 5.6% (RRR, 69%) for vision, 4.6% (RRR, 87%) for comprehension of language, 8.3% (RRR, 88%) for fluency of speech, 4.3% (RRR, 84%) for swallowing, 6.0% (RRR, 53%) for lower-limb function, 9.3% (RRR, 75%) for upper-limb function, 7.4% (RRR, 60%) for shopping, and 10.5% (RRR, 50%) for visiting outside usual residence (P < .05, two-tailed, for all items). CONCLUSIONS: Carotid endarterectomy reduced the risk for impairment of function among patients with recent symptomatic cerebral ischemia and ipsilateral high-grade carotid stenosis.

Carotid Artery, Internal↗
PubMed1994

Early endarterectomy for severe carotid artery stenosis after a nondisabling stroke: results from the North American Symptomatic Carotid Endarterectomy Trial.

PURPOSE: The timing of carotid endarterectomy (CE) after a recent nondisabling stroke remains controversial. Delaying surgery in such cases may needlessly place patients at risk for a recurrent stroke that may be major and disabling. This study examines the prognostic implications of performing early endarterectomy compared with delayed endarterectomy in patients from the North American Symptomatic Carotid Endarterectomy Trial. METHOD: This retrospective, subgroup analysis involved 100 surgical patients with severe (70% to 99%) angiographically defined carotid artery stenosis, who were diagnosed with a nondisabling hemispheric stroke at entry into the trial. Forty-two CEs were performed within 30 days (early group, ranging 3 to 30 days), and 58 were performed beyond 30 days (delayed group, range 33 to 117 days) after stroke. The risk of subsequent stroke after CE was compared between the two groups. RESULTS: Baseline clinical characteristics were comparable in both the early and delayed groups. In the delayed group more lesions were identified ipsilateral to the symptomatic side on the preoperative computed tomography scans. The postoperative (30 days after endarterectomy) stroke rate was 4.8% in the early group and 5.2% in the delayed group, yielding a relative rate of 0.92 (95% confidence interval, 0.16 to 5.27; p = 1.00). No deaths occurred after operation in either group. At the end of 18 months, the rates of any stroke or death were 11.9% and 10.3% for the early and delayed groups, respectively, resulting in a relative rate of 1.15 (95% confidence interval, 0.38 to 3.52; p = 1.00). No association was found between an abnormal preoperative computed tomography scan result and the subsequent risk of stroke when early operation was used. CONCLUSION: Early CE for severe carotid artery stenosis after a nondisabling ischemic stroke can be performed with rates of morbidity and mortality comparable to those who receive delayed endarterectomy. Delaying the procedure by 30 days for patients with symptomatic high-grade stenosis exposes them to a risk of a recurrent stroke, which may be avoidable by earlier surgery.

Aged↗
PubMed1994

Significance of plaque ulceration in symptomatic patients with high-grade carotid stenosis. North American Symptomatic Carotid Endarterectomy Trial.

BACKGROUND AND PURPOSE: The importance of carotid plaque ulceration as a cause of cerebral ischemic symptoms remains uncertain. Moreover, its prominence in symptomatic patients with severe carotid stenosis is unknown. METHODS: The association between angiographically defined plaque ulceration and risk of subsequent stroke was assessed using Cox proportional hazards regression in 659 patients with severe (70% to 99%) carotid stenosis from the North American Symptomatic Carotid Endarterectomy Trial. RESULTS: Treatment assignment (medical versus surgical) and degree of ipsilateral stenosis were identified as having a significant influence on the results. The risk of ipsilateral stroke at 24 months for medically treated patients with ulcerated plaques increased incrementally from 26.3% to 73.2% as the degree of stenosis increased from 75% to 95%. For patients with no ulcer, the risk of stroke remained constant at 21.3% for all degrees of stenosis. The net result yielded relative risks of stroke (ulcer versus no ulcer) ranging from 1.24 (95% confidence interval, 0.61 to 2.52) to 3.43 (95% confidence interval, 1.49 to 7.88). Conversely, for surgically treated patients with antecedent presence of an ulcerated plaque, the risk of stroke increased slightly at the highest degrees of stenosis. Overall, carotid endarterectomy reduced the risk of ipsilateral stroke at 24 months by at least 50%. Similar results were obtained for risk of major ipsilateral stroke and risk of all strokes and death. CONCLUSIONS: The presence of angiographically defined ulceration for medically treated symptomatic patients is associated with an increased risk of stroke. The risk of stroke more than doubles at higher degrees of stenosis. Carotid endarterectomy is beneficial in substantially reducing the risk of stroke, regardless of plaque ulceration and degree of severe carotid stenosis.

Carotid Artery Diseases↗
PubMed1994

Angiographic detection of carotid plaque ulceration. Comparison with surgical observations in a multicenter study. North American Symptomatic Carotid Endarterectomy Trial.

BACKGROUND AND PURPOSE: Carotid plaque ulceration is used as one of the determinants in deciding which patients should be submitted to carotid endarterectomy. Uncertainties about its importance persist. Its detection by angiography is an important consideration. METHODS: The detection of ulceration by angiography was compared with observations during endarterectomy in the first 500 patients recruited into the North American Symptomatic Carotid Endarterectomy Trial. This represents the first multicenter compilation of data on this subject and the largest series of patients with both arteriographic and direct surgical observation. RESULTS: Sensitivity and specificity of detecting ulcerated plaques were 45.9% and 74.1%, respectively. The positive predictive value of identifying an ulcer was 71.8%. These results remained unchanged with differing degrees of carotid stenosis and were confirmed by analyses based on receiver operating characteristic (ROC) methodology. The area under the ROC curve (Az) was estimated to be 0.61 (95% confidence interval, 0.55 to 0.67). CONCLUSIONS: These observations from a multicenter study confirm that little agreement exists between angiography and surgical observation in detecting carotid plaque ulceration.

Angiography↗
PubMed1994

Basilar artery dissection: an early postoperative complication of aneurysm clipping. Case report.

Recurrent subarachnoid hemorrhage (SAH) in the early period following successful clipping of a cerebral aneurysm is unusual. The authors report a unique case of distal basilar artery dissection and fatal SAH on the 6th day postoperatively. It is concluded that this complication was related to vascular trauma inflicted by repositioning the aneurysm clips during a seemingly uneventful procedure for a basilar artery tip aneurysm.

Adult↗
PubMed1994

Hunterian proximal arterial occlusion for giant aneurysms of the carotid circulation.

Hunterian proximal artery occlusion was used in the treatment of 160 of 335 patients harboring giant aneurysms of the anterior circulation. One hundred and thirty-three of these aneurysms arose from the internal carotid arteries, 20 from the middle cerebral arteries, and seven from the anterior cerebral arteries. Ninety percent of the patients had satisfactory outcomes. The safety of internal carotid artery occlusion has been greatly enhanced by preoperative flow studies and by test occlusion with an intracarotid balloon to identify those patients who require preliminary extracranial-to-intracranial bypass, which was used in all of the middle cerebral occlusions. The anterior cerebral artery had magnificent leptomeningeal collateral flow that prevented infarction even without cross flow. Obliteration of the aneurysm by thrombosis was complete, or nearly so, in all but four patients whose treatment was completed. Analysis of poor outcome in 16 patients revealed that hemodynamic ischemic infarction was known to occur after only two of the carotid occlusions.

Adult↗
PubMed1991

Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis.

BACKGROUND: Without strong evidence of benefit, the use of carotid endarterectomy for prophylaxis against stroke rose dramatically until the mid-1980s, then declined. Our investigation sought to determine whether carotid endarterectomy reduces the risk of stroke among patients with a recent adverse cerebrovascular event and ipsilateral carotid stenosis. METHODS: We conducted a randomized trial at 50 clinical centers throughout the United States and Canada, in patients in two predetermined strata based on the severity of carotid stenosis--30 to 69 percent and 70 to 99 percent. We report here the results in the 659 patients in the latter stratum, who had had a hemispheric or retinal transient ischemic attack or a nondisabling stroke within the 120 days before entry and had stenosis of 70 to 99 percent in the symptomatic carotid artery. All patients received optimal medical care, including antiplatelet therapy. Those assigned to surgical treatment underwent carotid endarterectomy performed by neurosurgeons or vascular surgeons. All patients were examined by neurologists 1, 3, 6, 9, and 12 months after entry and then every 4 months. End points were assessed by blinded, independent case review. No patient was lost to follow-up. RESULTS: Life-table estimates of the cumulative risk of any ipsilateral stroke at two years were 26 percent in the 331 medical patients and 9 percent in the 328 surgical patients--an absolute risk reduction (+/- SE) 17 +/- 3.5 percent (P less than 0.001). For a major or fatal ipsilateral stroke, the corresponding estimates were 13.1 percent and 2.5 percent--an absolute risk reduction of 10.6 +/- 2.6 percent (P less than 0.001). Carotid endarterectomy was still found to be beneficial when all strokes and deaths were included in the analysis (P less than 0.001). CONCLUSIONS: Carotid endarterectomy is highly beneficial to patients with recent hemispheric and retinal transient ischemic attacks or nondisabling strokes and ipsilateral high-grade stenosis (70 to 99 percent) of the internal carotid artery.

Aged↗
PubMed1991

Monitoring electrophysiologic function during carotid endarterectomy: a comparison of somatosensory evoked potentials and conventional electroencephalogram.

There is no consensus as to the most appropriate monitor for detecting ischemia during carotid endarterectomy. Accordingly, simultaneous 16-channel continuous electroencephalogram (EEG) and somatosensory evoked potential (SSEP) monitoring were performed in 64 normocapnic patients undergoing carotid endarterectomy and anesthetized with isoflurane or halothane-nitrous oxide (supplemented with fentanyl). Recordings were obtained before, during, and for 15 min after cross-clamping of the internal carotid artery. Internal shunt was not used in any patient, regardless of EEG and SSEP changes. Significant amplitude reduction in the cortical component of the primary negative peak (greater than 50%) in SSEP occurred in 6 patients, and an increase in central conduction time (CCT) (greater than 1 ms) occurred in 5 patients. Major EEG changes occurred in 6 patients, 4 of whom also had SSEP changes. Two patients had transient neurologic deficits postoperatively, with both having SSEP changes (amplitude reduction greater than 50%), whereas one had EEG changes. Based on these observations, the relative sensitivity and specificity for EEG and SSEP (amplitude reduction greater than 50%) in detecting postoperative neurologic deficits were 50% and 92% for EEG and 100% and 94% for SSEP, respectively, differences that were not statistically significant. Regarding SSEP, the use of latency change (CCT) as a criterion was associated with a sensitivity of 0% (P = 0.046 from sensitivity of amplitude) and a specificity of 87% (P = 0.17 from specificity of amplitude).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Neuropsychological improvement versus practice effect following unilateral carotid endarterectomy in patients without stroke.

Patients who were admitted to hospital for a recent transient ischemic attack were entered into one of three groups based on medical and surgical characteristics; those with an abnormal neurological examination or a focal abnormality on CT Scan were omitted from the study. The two surgical groups (12 patients each) underwent either a left or right endarterectomy for a symptomatic atheroma of the ipsilateral carotid artery. The control group consisted of 12 patients who either demonstrated minor or nonexistent carotid abnormalities or a TIA distribution that was contralateral to what would otherwise have been a surgically treatable lesion. Patients were tested before surgery and again 6-8 weeks later with the WAIS, WMS, and other neuropsychological measures. Significant improvement on some measures at follow-up was strictly equivalent across all groups and was attributed to practice effects.

Aged↗
PubMed1987

Use of detachable balloons for proximal artery occlusion in the treatment of unclippable cerebral aneurysms.

Of 68 patients with unclippable aneurysms treated by proximal artery occlusion with detachable balloons, permanent occlusion was achieved in 65; of these patients, 37 had carotid artery aneurysms below the origin of the ophthalmic artery, 21 had aneurysms arising from the supraclinoid portion of the carotid artery, six had basilar trunk aneurysms, and one had a distal vertebral aneurysm. Examination for treatment selection included assessment of the circle of Willis by compression angiography and xenon blood flow studies, with the ultimate evaluation being test occlusion under systemic heparinization with the balloon temporarily placed in the desired position. Of 67 patients who underwent a formal occlusion test, eight with carotid artery aneurysms did not initially tolerate the occlusion test, and ischemic signs disappeared instantaneously with deflation and removal of the balloon. During test occlusion, two additional patients had ischemic events that proved to be embolic; these reversed immediately upon balloon deflation. Of the 65 patients in whom permanent occlusion was effected by detachable balloon, there were nine instances of delayed cerebral events. One of these was a seizure leading to respiratory arrest and resuscitation 3 days following occlusion in a patient who had presented with seizures. The other eight cases were delayed ischemic events; seven were completely reversed and one patient had residual weakness in one leg (1.5% permanent morbidity). Extracranial-intracranial bypass procedures were performed in 25 of the 65 cases. All aneurysms of the carotid artery below the level of the ophthalmic artery presented angiographic proof of complete thrombosis. Ten of 21 aneurysms arising from the supraclinoid portion of the carotid artery were completely thrombosed by proximal occlusion alone, without additional trapping procedures. Similarly, in three of six basilar trunk aneurysms, proximal occlusion alone initiated complete aneurysm thrombosis without trapping. The conclusion is that proximal balloon occlusion for unclippable cerebral aneurysms is a convenient, safe, and effective way of producing arterial occlusion in these cases.

Carotid Artery Diseases↗
PubMed1987

Intravenous digital subtraction angiography and duplex ultrasonography in postoperative assessment of carotid endarterectomy.

Seventy-four consecutive patients who had undergone carotid endarterectomy procedures were examined with intravenous digital subtraction angiography (IV-DSA) and duplex ultrasonography (DUS) at intervals ranging from 1 to 14 months postoperatively. Ninety-one percent of the DUS and 74% of the DSA images were of diagnostic quality. The two modalities agreed in the assessment of the endarterectomy appearance in 84% of the arteries, with 85% showing no evidence of significant residual disease. There were no arteries with severe restenosis or complete occlusion. In the 10 vessels in which the two modalities disagreed in disease assessment, the IV-DSA images were often degraded by artifact or vessel overlap leading to underestimation of disease. The authors conclude that DUS is the examination of choice for routine follow-up studies of carotid endarterectomy.

Arteriosclerosis↗