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Mural thrombosis after experimental carotid endarterectomy.

The incidence of mural thrombosis following three types of experimental intimal injuries at common carotid arteries, was investigated in a series of 12 dogs. Mural thrombosis was obtained at each of the intimal lesions. Moreover, obstructive thrombosis occurred in three instances. Further investigation of thrombi revealed that partial fragmentation occurred when exposed to hydrodynamic forces. These results suggest that mural thrombosis following carotid endarterectomy in humans, is possibly more frequent and significant than it is generally appreciated, thus leading to the consideration of postoperative anticoagulation after endarterectomy, as a means to minimize the incidence of postoperative embolic cerebrovascular accidents.

Animals↗

Carotid endarterectomy without shunt: the role of cerebral metabolic protection.

BACKGROUND: The optimal method to protect the brain from hemodynamic ischemia during carotid endarterectomy (CEA) remains controversial. This study reports our experience with induced arterial hypertension and selective etomidate cerebral protection in a cohort of patients who underwent CEA without shunting and continuous electroencephalography (EEG) monitoring. METHODS: We reviewed retrospectively 102 consecutive CEAs performed in 102 patients with routine EEG monitoring and general anesthesia between March 1998 and October 2002. There were 65 (66%) symptomatic and 37 (34%) asymptomatic individuals. A protocol of induced arterial hypertension against EEG ischemic changes during carotid artery cross clamping was followed. Only patients with EEG changes refractory to induced hypertension went into etomidate-induced burst suppression. RESULTS: EEG changes were classified as mild, moderate and severe. Twenty patients (19.6%) developed asymmetric EEG changes, of which the great majority were mild and moderate (75%, p< 0.05). Seven patients with moderate (n=3) and severe (n=4) EEG changes needed etomidate cerebral protection. There were no mortalities and only one stroke (0.98%) is reported in the series. The morbidity rate was 6.8% and included transient cranial nerve palsies (n=5) and wound hematoma (n=1). CONCLUSIONS: Carotid endarterectomy can be safely performed with EEG monitoring and selective induced arterial hypertension and etomidate cerebral protection. Our results suggest that this method may be a good alternative for shunting and its inherent risks.

Adult↗

Has evidence changed practice?: appropriateness of carotid endarterectomy after the clinical trials.

OBJECTIVE: To assess how appropriateness of and indications for carotid endarterectomy (CEA) have changed following the publication of several large international randomized controlled trials (RCTs) designed to rationalize use of CEA. METHODS: The New York Carotid Artery Surgery Study (NYCAS) is a population-based cohort study of all CEAs performed on elderly patients from January 1998 through June 1999 in New York State. Detailed clinical data were abstracted from medical charts to assess indications for and appropriateness of surgery using a list of 1,557 indications for CEA developed by national experts using RAND appropriateness methods. Deaths and strokes within 30 days of surgery were ascertained and confirmed by two physicians. RESULTS: Among the 9,588 patients, the mean age was 74.6 years and 93.6% had 70 to 99% carotid stenosis. Nearly three-quarters of patients (72.3%) underwent CEA for asymptomatic stenosis, 18.6% for TIA, and 9.1% for stroke. Overall, 87.1% of operations were done for appropriate reasons, 4.3% for uncertain reasons, and 8.6% for inappropriate reasons (vs 32% inappropriate before the RCTs, p < 0.0001). Among procedures judged inappropriate, the most common reasons were high comorbidity in asymptomatic patients (62.2%), operating after a major stroke (14.2%), or for minimal stenosis (10.5%). Among asymptomatic patients, those with high comorbidity had over twice the risk of death or stroke compared to those without high comorbidity (7.13% vs 2.69%, p < 0.0001). CONCLUSIONS: Since publication of the randomized controlled trials, there has been a reduction in the proportion of patients undergoing carotid endarterectomy (CEA) for inappropriate reasons. The shift toward many asymptomatic patients undergoing CEA is concerning because the net benefit from surgery for these patients is low and is reduced further for patients with high comorbidity.

Aged↗

Do the facts and figures warrant a 10-fold increase in the performance of carotid endarterectomy on asymptomatic patients?

The detailed results of the Asymptomatic Carotid Atherosclerosis Study (ACAS) have been published. Electrifying reports in the media suggested that 53% fewer strokes would occur if individuals with 60% or greater stenosis were submitted to endarterectomy. The burning question is whether the evidence from this trial, and those preceding it, is sufficiently compelling to persuade any or all individuals with carotid stenosis, but free of any hemisphere and retinal symptoms, to have carotid endarterectomy. Based on a variety of population samplings, it is reasonable to estimate that approximately two million people are living in North America and Europe with asymptomatic lesions comparable with those studied in the ACAS.

Carotid Stenosis↗

II. Improved dark adaptation after carotid endarterectomy. Evidence of a long-term ischemic penumbra?

We have reported that dark vision is impaired in symptomatic carotid artery disease and that the impairment correlates with internal carotid artery stenosis. To find out whether this impairment is reversible after carotid endarterectomy, dark adaptation was examined pre- and postoperatively. Twenty-one consecutive patients were examined by dark adaptometry. Two examinations were done for each eye on two consecutive days pre- and postoperatively. Thirty-one matched control subjects were examined under identical conditions. The control subjects did not have clinical evidence of carotid artery disease. Patients and control subjects were free of ophthalmologic disorders. Dark vision frequently improved remarkably after endarterectomy. The average retinal sensitivity to light in darkness on the operated side doubled, and there was also improvement on the nonoperated side. There was no significant change in dark vision in the control subjects, negating a learning effect. The findings suggest the existence of reversible neuronal ischemia secondary to hemodynamic causes or frequent subclinical microembolization. Because the circulatory conditions are optimized, formerly inactive, surviving neurons may regain function.

Aged↗

Small, unruptured intracranial aneurysms and management of symptomatic carotid artery stenosis. North American Symptomatic Carotid Endarterectomy Trial Group.

Of the 2885 patients participating in the North American Symptomatic Carotid Endarterectomy Trial, 90 (3.1%) had unruptured intracranial aneurysms (UIA), of which 96% had a diameter of less than 10 mm. During an average 5-year follow-up, only one patient had subarachnoid hemorrhage 6 days after carotid endarterectomy (CE). For patients with unrepaired UIA, the 5-year stroke risk was 10% after CE and 22.7% with best medical care. Both risks are similar to those of patients without UIA. The decision regarding CE probably should not be influenced by the presence of a small UIA.

Aged↗

The use of argatroban for carotid endarterectomy in heparin-induced thrombocytopenia.

Heparin-induced thrombocytopenia (HIT) is a major obstacle in cardiovascular surgeries. In this case report, we used argatroban, a direct thrombin inhibitor, to achieve and maintain anticoagulation for carotid endarterectomy. Unlike heparin, the direct thrombin inhibitors bind directly to thrombin, bypassing antithrombin III and the potential to precipitate HIT. A bolus of argatroban 150 microg/kg followed by an infusion of 5 microg . kg(-1) . min(-1) was used, and adequate anticoagulation was demonstrated with multiple laboratory tests (at 28 min, prothrombin time = 29.8 s, partial thromboplastin time = 69.1 s, international normalized ratio = 3.52 s, and activated clotting time = 220 s). The surgery was successful, and the patient was discharged the next day with no postoperative neurologic sequelae or other complications. We conclude that argatroban can be used safely and successfully for carotid endarterectomy in a patient with a history of HIT.

Aged↗

Microsurgical endarterectomy of the intracranial vertebral artery for vertebrobasilar transient ischemic attacks.

Two patients who had typical vertebrobasilar transient ischemic attacks (TIAs) that were refractory to anticoagulation with dicumarol and to antiplatelet therapy with aspirin and/or dipyridamole are described. Angiography revealed in both patients a stenotic atherosclerotic plaque of the intracranial vertebral artery between the posterior and anterior inferior cerebellar arteries. At operation, the first patient had an atherosclerotic plaque extending into the basilar artery, and no endarterectomy was attempted. The second patient had a 1-cm localized plaque that was removed successfully from the vertebral artery. Neither patient sustained a neurological deficit as a result of the operation. The patient whose plaque was not removed at operation continues to have vertebrobasilar TIAs and suffered a brain stroke 2 weeks after operation. The patient whose plaque was removed at operation continues to be free of TIAs 8 months later, and angiography performed 3 months after operation showed a widely patent vertebral artery. A portion of the intracranial vertebral artery has now been shown to be accessible to endarterectomy using the operating microscope. Angiography is helpful in determining this accessibility preoperatively.

Aged↗

Carotid endarterectomy without shunt.

This series of 280 consecutive carotid endarterectomies was performed on 222 patients without an indwelling shunt or electroencephalograpic monitoring. Symptomatic patients with lateralized and nonlateralized transient ischemic attacks, ulcerated atherosclerotic plaques. One-third of the patients had severe bilateral stenosis or unilateral stenosis and contralateral occlusion. Adequate cerebral protection was provided during operation by general anesthesia and moderate hypertension. The carotid occlusion time averaged 10 minutes. There was no operative mortality within 30 days. There were no strokes during carotid occlusion and only three strokes (1.1%) within 1 month of operation. Follow-up data are available on 93% of the patients. Indwelling shunts, electroencephalographic monitoring, and carotid back pressure measurements are not necessary for the safe performance of carotid endarterectomy.

Adult↗

Perioperative management of high risk patients with cardiopulmonary disease undergoing carotid endarterectomy or extracranial-intracranial bypass.

Among a large group of patients who underwent either carotid endarterectomy or extracranial-intracranial (EC-IC) bypass were 13 patients who had cardiopulmonary monitoring performed by a dye dilution technique either with or without a thermodilution Swan-Ganz catheter. Each patient had at least two significant medical problems that were thought to place him or her at increased risk. The usefulness of this monitoring approach in the perioperative management of these patients is demonstrated by several clinical examples. No patient sustained myocardial infarction, congestive heart failure, or new neurological deficit during the perioperative period. Our experience suggests that high risk patients can safely undergo either carotid endarterectomy or EC-IC bypass provided that careful attention is paid to myocardial function and the state of hydration.

Aged↗

Current status of carotid endarterectomy for atheromatous disease.

The authors discuss the indications for both elective and emergency carotid endarterectomy. Reports on the surgical treatment of asymptomatic bruit and contralateral carotid stenosis are reviewed. The results of endarterectomy for symptomatic carotid disease, including transient ischemic attacks, acute neurological deficit, and complete carotid occlusion, are discussed. The complications and risks of carotid surgery are also presented.

Carotid Artery Diseases↗

Cerebral hyperperfusion after carotid endarterectomy: a cause of cerebral hemorrhage.

Correction of a very high grade carotid stenosis by endarterectomy in a normotensive man was followed by the development of severe unilateral head, eye, and face pain, seizures, and on the 6th day a fatal intracerebral hemorrhage. Autopsy revealed changes in the cerebral hemisphere ipsilateral to the endarterectomy that resembled the changes seen in malignant hypertension, whereas the opposite hemisphere was normal. These changes included hypercellularity and edema of arterial and arteriolar walls, with necrosis, extravasation of erythrocytes, and exudation of fibrin. We propose that the clinical and pathological features in this case were due to relative hyperperfusion of a cerebral hemisphere in which autoregulation had been impaired because of preoperative chronic hypoperfusion with chronic maximal dilatation of its blood vessels. This state of relative hyperperfusion is probably similar to the normal perfusion pressure breakthrough that occasionally occurs after the resection of cerebral arteriovenous malformations. It is similar to the breakthrough perfusion that occurs in severely hypertensive patients and results in hypertensive encephalopathy.

Arterioles↗

Effect of antithrombotic agents after carotid endarterectomy in rats.

The pharmacological prevention of thrombosis after surgical arterial injury is still an open question. In the present study, a recently developed model of carotid endarterectomy in rats was used to assess the effectiveness of heparin, prostacyclin (PGI2), and OKY-1581, a selective thromboxane A2 (TXA2) synthetase inhibitor, in preventing thrombus formation. Thirty-six male Sprague-Dawley rats were divided into six groups: A--controls (no treatment), B--tris (hydroxymethyl) aminomethane (Tris)-HCl buffer (vehicle of PGI2), C--heparin (100 IU/kg), D--OKY-1581 (100 microns/kg/minute), E--low dose PGI2 (10 ng/kg/minute), F--high dose PGI2 (50 ng/kg/minute). The animals were killed by in vivo perfusion-fixation 15 minutes after recirculation. The endarterectomized vessels were submitted to scanning electron microscopy examination and were evaluated blindly according to the following scale: 1, (almost) normal appearance of the endarterectomized surface; 2, moderately abnormal appearance; and 3, definitely abnormal appearance. The results in terms of thrombus prevention were as follows: controls congruent to Tris-HCl buffer less than OKY-1581 congruent to low dose PGI2 less than high dose PGI2 less than heparin. When combined, the two control groups did significantly worse than all four treated groups (P greater than 0.05). Fisher's exact test showed a statistically significant difference between controls and the heparin group (P = 0.01) and between controls and high dose PGI2-treated rats (P less than 0.05), but not between controls and low dose PGI2-(P less than 0.16) or OKY-1581-treated animals (P less than 0.16). In conclusion, the present study confirms that anticoagulation with heparin is effective in reducing thrombus formation after carotid endarterectomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Early carotid endarterectomy after cerebral infarction.

The objective of the study was to review our recent experience with carotid endarterectomy performed within 30 days of completed cerebral infarction and to evaluate the role of computed tomographic (CT) scanning in the decision-making process. Twenty-seven of 302 operations (9%) were carried out during the 30-day time period. The mean interval between cerebral infarction and surgery was 14 days. Angiography revealed severe stenosis (greater than 75%) of the internal carotid artery in 19 patients. Severe stenosis with deep ulceration found in 6 patients and moderate stenosis (i.e., 50-75%) with deep ulceration was found in 2 patients. CT scans showed recent infarction in 4 patients and an old subcortical lacune in 2 patients. Twenty-two patients were neurologically stable with mild deficits and showed normal results on a CT scan performed 24 hours or more after the ischemic event. These patients underwent early cerebral angiography and carotid endarterectomy without permanent morbidity or mortality. Two patients with moderate stable neurological deficits and findings of recent infarction on CT scans had uneventful postoperative courses. Five patients who were neurologically unstable underwent surgery. The 2 patients with repeated transient ischemic attacks and normal findings on CT scans had uneventful postoperative courses. Two of the three patients with progressive neurological deficits and CT findings of recent cerebral infarction experienced extension of their infarcts after surgery. One of these patients died. Our personal experience, together with a review of previous reports, indicated that patients who have minimal residual neurological deficits and whose CT scans show normal findings are at low surgical risk, perhaps approaching that of patients with transient ischemic attacks.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Ischemia↗

Correlation of contralateral stenosis and intraoperative electroencephalogram change with risk of stroke during carotid endarterectomy.

Two hundred ninety-three carotid endarterectomies were performed with electroencephalogram (EEG) monitoring and without the use of a shunt. Two hundred sixteen patients had contralateral carotid stenosis of less than 70%; 45 had contralateral stenosis of 70 to 99%; and 32 had contralateral occlusion. There were six perioperative strokes (2.0%) and two deaths (0.7%). Major EEG changes were seen in 11 of the 77 patients (14.3%) with significant contralateral stenosis or occlusion versus 11 of the 216 patients (5.1%) in those without (P less than 0.025). The risk of immediate postoperative deficit was significantly higher in the subgroup with major EEG changes (4 of 22, 18.2%) than in those without such changes (5 of 271, 1.8%) (P less than 0.005). The risk in patients with less than 70% contralateral stenosis (7 of 216, 3.2%) was not significantly different from those with greater contralateral stenosis or occlusion (2 of 77, 2.6%). Carotid endarterectomy can be safely performed without a temporary shunt. Contralateral stenosis or occlusion alone does not confer increased risk. Major EEG changes are infrequent, but they identify a subgroup with significantly higher risk of intraoperative stroke.

Adult↗

Preoperative risks predict neurological outcome of carotid endarterectomy related stroke.

The aim of this study was to determine if preoperative risk factors are predictors of poor stroke outcome after carotid endarterectomy. In addition, the effect of other stroke risk factors on stroke severity was determined. A retrospective review of carotid endarterectomy results spanning 10 years, encompassing 561 patients, and reporting the combined results of all surgeons at our institution was performed. Patients were assigned to one of four groups. There were 227 patients with no preoperative risks (Group 1), 61 with angiographic risks (Group 2), 196 with medical risks with or without angiographic risks (Group 3), and 77 with neurological risks with or without medical/angiographic risks (Group 4). Other risks associated with stroke occurrence were recorded including: intraoperative risks (cross-clamp time, use of shunt, use of glucose solutions), surgical complications (carotid occlusion/thrombus or ligation), and medical complications (hypoxia, myocardial infarct). Stroke incidence was 5% with 2% (11 patients) and 3.4% (19 patients) having good and poor outcomes, respectively. Stroke incidence was highest in Groups 2 and 4 (10 and 14%, respectively), and Group 4 had the highest incidence of poor-outcome stroke (12%). Cross-clamp time, intraoperative shunt placement, and intraoperative glucose administration were similar among preoperative risk groups and were not primary determinants of stroke severity. The most common medical complication was myocardial infarction, which had the highest incidence in Groups 3 and 4 (6.1 and 5%, respectively). The highest incidence of surgical complications occurred in Groups 2 and 4, carotid thrombosis being the most common event (16 patients). Surgical complications were more commonly associated with stroke than were medical complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

Direct endarterectomy of the middle cerebral artery for treatment of symptomatic stenosis: case report.

The authors report the clinical course and surgical technique used to treat a patient with a high-grade stenosis of the proximal middle cerebral artery that had caused a previous infarction and threatened the remaining dominant hemisphere. Trapping of the involved middle cerebral artery segment allowed direct exposure for excision of the atheromatous plaque and subsequent closure of the arteriotomy. Intraoperative angiography confirmed the reestablishment of flow. The patient made an uneventful postoperative recovery. Direct middle cerebral artery endarterectomy has the advantage of potentially reestablishing flow to lenticulostriate branches. The technique may also avoid the problem of occlusion at the site of maximum stenosis that can be caused by the use of an extra/intracranial bypass graft. Middle cerebral artery endarterectomy is a potentially valuable technique that deserves further investigation.

Cerebral Angiography↗

Endarterectomy of the intradural vertebral artery via the far lateral approach.

Transient ischemic attacks (TIAs) of the posterior circulation are associated with a significant risk of subsequent infarction, particularly when caused by stenotic lesions in the intracranial portion of the vertebral artery (VA). Eight patients who had persistent posterior circulation TIAs despite receiving maximal medical therapy (including anticoagulation) and who had angiographic evidence of severe stenosis of the proximal intracranial VA with poor collateral flow were treated by endarterectomy of the intradural VA. Their ages ranged from 52 to 65 years. Five of these operations were performed via the far lateral approach. In all patients, the contralateral VA was hypoplastic or occluded, or ended in the posterior inferior cerebellar artery. Postoperative angiograms showed that the arteries of five of the patients were widely patent, one was improved but still stenotic, and two were occluded. The latter two patients subsequently underwent thrombectomy, after which the artery was patent in one patient and remained occluded in the other. After surgery, the TIAs of seven patients were relieved completely, and the patients were neurologically intact. The patient with persistent occlusion ultimately had moderate disability. Complications included the two cases of thrombotic occlusion that required a second operation, three cases of communicating hydrocephalus that required lumboperitoneal shunts, and two cases of transient dysfunction of the 9th and 10th cranial nerves. Suitable patients with persistent posterior circulation TIAs refractory to medical therapy who have appropriate angiographic evidence of proximal VA stenosis and poor collateral flow may benefit from endarterectomy of the intradural VA.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗