Causes of perioperative stroke after carotid endarterectomy: special considerations in symptomatic patients.

In order to maximize the efficacy of carotid endarterectomy (CEA), the rate of perioperative stroke must be kept to a minimum. A recent analysis of carotid surgery at our institution found that most perioperative strokes were due to technical errors resulting in thrombosis or embolization. From 1992 through 1997 we have performed nearly 1200 additional CEAs; the purpose of this study was to examine recent trends in the causes of perioperative stroke, with specific attention to differences in symptomatic and asymptomatic patients. The records of 1041 patients undergoing 1165 CEAs were reviewed from a prospectively compiled database. Analysis of these data showed that a history of preoperative stroke appears to increase the risk of perioperative stroke after CEA. Surgical factors associated with perioperative stroke include an inability to tolerate clamping, use of an intraarterial shunt, and having surgery performed under general anesthesia; these factors are clearly interrelated and only the use of intraarterial shunting remains a risk factor by multivariate analysis. Over half of all perioperative strokes (54%) appear to be caused by intraoperative or postoperative thrombosis and embolization. The patient requiring use of intraarterial shunting and/or with a preoperative stroke most likely has a significant watershed area of brain at increased risk of infarction. However, technical errors are still the most common cause of perioperative stroke in these high-risk patients. Such high-risk patients may manifest clinical stroke from small emboli that may be tolerated by asymptomatic clamp-tolerant patients. Technical precision and appropriate cerebral protection are particularly critical for successful outcomes in high-risk patients.

Anesthetic methods in reoperative carotid surgery.

It has been suggested that general anesthesia is the preferred method for reoperative carotid surgery for several reasons, including: the difficulty of the reoperative dissection; the disease may extend unusually high into the internal carotid artery; and the reconstruction required may be more complex than a typical endarterectomy. The purpose of this study is to show that reoperative carotid surgery can be performed safely under regional anesthesia. The records of 109 reoperative carotid operations performed on 96 patients over the past 25 years were reviewed. Procedures performed under regional anesthesia were compared to those performed under general anesthesia with respect to patient characteristics, intraoperative courses, and perioperative results. Regional anesthesia was utilized in 79 operations (72.5%); 30 operations were performed with general anesthesia (27.5%). The two patient groups were essentially equivalent with regard to atherosclerotic risk factors, preoperative neurologic symptoms, and the prevalence of contralateral total occlusion. The etiologies for recurrent disease included recurrent atherosclerosis (50.4%), intimal hyperplasia (30.3%), and vein patch aneurysm (9.2%). The methods of reconstruction employed included saphenous vein patch (47.7%), vein interposition graft (11.9%), prosthetic patch (20.2%), and prosthetic graft (20.2%). Perioperative strokes occurred in one case performed under regional anesthesia (1.3%), and in two cases under general anesthesia (6.6%); this difference was not statistically significant. Reoperative carotid artery surgery can be performed under regional anesthesia safely in the majority of instances. The aforementioned theoretical factors in favor of general anesthesia could also lead to technical difficulties with intraarterial shunt insertion. Having the patient awake, even if just long enough to prove that the patient will tolerate carotid artery clamping, might simplify many of these operations by avoiding shunt insertion. Regional anesthesia should therefore be considered an acceptable option in cases of reoperative carotid surgery.

A comparison of regional and general anesthesia in patients undergoing carotid endarterectomy.

PURPOSE: The optimal anesthetic for use during carotid endarterectomy is controversial. Advocates of regional anesthesia suggest that it may reduce the incidence of perioperative complications in addition to decreasing operative time and hospital costs. To determine whether the anesthetic method correlated with the outcome of the operation, a retrospective review of 3975 carotid operations performed over a 32-year period was performed. METHODS: The records of all patients who underwent carotid endarterectomy at our institution from 1962 to 1994 were retrospectively reviewed. Operations performed with the patient under regional anesthesia were compared with those performed with the patient under general anesthesia with respect to preoperative risk factors and perioperative complications. RESULTS: Regional anesthesia was used in 3382 operations (85.1%). There were no significant differences in the age, gender ratio, or the rates of concomitant medical illness between the two patient populations. The frequency of perioperative stroke in the series was 2.2%; that of myocardial infarction, 1.7%; and that of perioperative death, 1.5%. There were no statistically significant differences in the frequency of perioperative stroke, myocardial infarction, or death on the basis of anesthetic technique. A trend toward higher frequencies of perioperative stroke (3.2% vs 2.0%) and perioperative death (2.0% vs 1.4%) in the general anesthesia group was noted. In examining operative indications, however, there was a significant increase in the percentage of patients receiving general anesthesia who had sustained preoperative strokes when compared with the regional anesthesia patients (36.1% vs 26.4%; p < 0.01). There was also a statistically significant higher frequency of contralateral total occlusion in the general anesthesia group (21.8% vs 15.4%; p = 0.001). The trend toward increased perioperative strokes in the general anesthesia group may be explicable either by the above differences in the patient populations or by actual differences based on anesthetic technique that favor regional anesthesia. CONCLUSIONS: In a retrospective review of a large series of carotid operations, regional anesthesia was shown to be applicable to the vast majority of patients with good clinical outcome. Although the advantages over general anesthesia are perhaps small, the versatility and safety of the technique is sufficient reason for vascular surgeons to include it in their armamentarium of surgical skills. Considering that carotid endarterectomy is a procedure in which complication rates are exceedingly low, a rigidly controlled, prospective randomized trial may be required to accurately assess these differences.

Long-term follow-up of patients undergoing carotid endarterectomy in the presence of a contralateral occlusion.

BACKGROUND: Patients with stenosis of one carotid artery and occlusion of the contralateral carotid artery (stenosis-occlusion) who are treated medically are at high risk for stroke. We have recently reported that carotid endarterectomy on the stenotic artery has a low perioperative risk in these patients. We now present follow-up data to define the long-term effectiveness of this operation. PATIENTS AND METHODS: From 1985 to 1991, 135 patients with stenosis-occlusion underwent endarterectomy of the stenotic carotid artery. Selective intra-arterial shunting was performed based on mental status changes under regional anesthesia, preoperative neurologic deficit, or evidence of preoperative cerebral infarction on computed tomography scan. Shunting was used in 70 patients (52%). Saphenous vein was used for patch closure in 132 patients (98%), and polytetrafluoroethylene in 3 (2%). RESULTS: By life-table analysis, 92% of patients have remained stroke-free at 5 years. Fourteen deaths, none related to cerebrovascular disease, have occurred during follow-up. The life-table cumulative stroke-free survival rate at 5 years is 74%, and the overall survival rate is 82%. CONCLUSION: Carotid endarterectomy in the presence of a contralateral occlusion provides long-term benefit to the patient with respect to prevention of stroke. With lower perioperative stroke rates and proven long-term benefit, carotid endarterectomy of the stenotic artery should be the treatment of choice in the patient with stenosis-occlusion.

Carotid endarterectomy in the presence of a contralateral occlusion: a review of 315 cases over a 27-year experience.

Recent data from the North American Symptomatic Carotid Endarterectomy Trial revealed a 14.3% perioperative risk of stroke or death with carotid endarterectomy contralateral to a carotid artery occlusion. Since last reporting on this topic in the mid-1980s, the authors have reviewed 180 patients with occlusion of one internal carotid artery (ICA) and who underwent endarterectomy of the stenotic contralateral ICA operated from 1965 to 1984 (group A) compared with 135 operated on from 1985 to 1991. The two groups were similar with respect to age, sex, incidence of coronary artery disease, hypertension, diabetes and history of smoking, but group B had a significantly increased incidence of patients who were neurologically symptom-free before surgery (21.5% versus 7.8%, P < 0.001). The combined perioperative stroke or death rate for patients in group B was significantly lower than for those in group A (0.7% versus 6.7%, P < 0.01). Comparison of the operative techniques showed more frequent placement of intra-arterial shunt (52.6% versus 29.4%, P < 0.001) and increased use of general anesthesia (20.0% versus 9.4%, P < 0.01) in patients of group B. Analysis of the etiology of the complications, however, showed that shunting alone could not account for the improved results. Lower incidences of postoperative thrombosis, embolization and intracerebral hemorrhage were equally important.(ABSTRACT TRUNCATED AT 250 WORDS)

Is there detrimental gender bias in preoperative cardiac management of patients undergoing vascular surgery?

BACKGROUND: To investigate the possibility of gender bias in the cardiac management of patients who undergo peripheral vascular surgery, we examined the hospital data and outcomes for 350 adult men and 128 women who underwent vascular surgery from September 1987 to December 1991. METHODS AND RESULTS: There were no significant differences between the two groups in age at operation, incidence of standard risk factors for myocardial infarction, or incidence or duration of episodes of perioperative silent ischemia. Nevertheless, a significantly lower percentage of women than men had undergone prior coronary bypass procedures (6.3% and 17.1%, respectively; P < .01), an apparent example of gender bias. However, there was no significant difference in the incidence of perioperative myocardial infarction in women (3.9%) compared with men (4.0%). Furthermore, actuarial analysis showed that at 24 months after operation a significantly higher percentage of women (77.9%) had escaped late cardiac death and cardiac complications than men (71.9%; P < .05). CONCLUSIONS: These findings indicate that apparent gender bias in the preoperative cardiac management of this group of women who underwent vascular surgery may have had no detrimental effect on short- and long-term incidence of cardiac death and complications, and may represent sound clinical judgment rather than true bias. However, the possibility that female patients might have had even better short- and long-term cardiac results if they had undergone more preoperative cardiac revascularization cannot be discounted.

The cause of perioperative stroke after carotid endarterectomy.

PURPOSE: The purpose of this study was to examine the cause of perioperative stroke after carotid endarterectomy. METHODS: The records of 2365 patients undergoing 3062 carotid endarterectomies from 1965 through 1991 were reviewed. Sixty-six (2.2%) operations were associated with a perioperative stroke. The mechanism of stroke was determined in 63 of 66 cases. Patient risk factors and surgeon-dependent factors were analyzed. RESULTS: More than 20 different mechanisms of perioperative stroke were identified, but most could be grouped into broad categories of ischemia during carotid artery clamping (n = 10), postoperative thrombosis and embolism (n = 25), intracerebral hemorrhage (n = 12), strokes from other mechanisms associated with the surgery (n = 8), and stroke unrelated to the reconstructed artery (n = 8). Dividing the operative experience approximately into thirds, during the years 1965 to 1979, 1980 to 1985, and 1986 to 1991 the perioperative stroke rates were 2.7%, 2.2%, and 1.5%, respectively. This, in part, is associated with a better selection of patients (more symptom free, fewer with neurologic deficits). There has been a notable decrease in perioperative stroke caused by ischemia during clamping and intracerebral hemorrhage, but postoperative thrombosis and embolism remain the major cause of neurologic complications. CONCLUSIONS: Although patient selection seems to play a role, most perioperative strokes were due to technical errors made during carotid endarterectomy or reconstruction and were preventable.

Long-term follow-up of patients undergoing reoperation for recurrent carotid artery disease.

PURPOSE: We examined the perioperative course and long-term fate of individuals who required reoperation for recurrent carotid artery disease. METHODS: The records of 2289 patients undergoing 2961 consecutive operations during a 22-year period were reviewed. Forty-two patients (1.8%) who underwent reoperations were studied. Forty-seven redo carotid artery reconstructions were performed on these 42 patients for neurologic symptoms or asymptomatic high-grade stenosis. Long-term follow-up was obtained on 41 of 42 patients (mean 54 months; range 9 to 202 months). RESULTS: The forty-seven reoperations consisted of endarterectomy with patch angioplasty (n = 36), saphenous vein or polytetrafluoroethylene interposition graft (n = 7), or simply vein or polytetrafluoroethylene patch angioplasty (n = 4). There were no perioperative strokes or deaths. Three patients had perioperative transient ischemic attacks and two had cranial nerve injuries. The incidence of late failure after secondary surgery was 19.5% (8/41 patients). These failures consisted of one stroke, three transient ischemic attacks, and four asymptomatic occlusions. One tertiary carotid artery reconstruction was performed for a restenosis at the site of the secondary reconstruction. CONCLUSION: The factors responsible for the high incidence of late failures after secondary carotid artery reconstruction are unclear. Reoperation for recurrent carotid artery disease appears less durable than primary carotid endarterectomy. Close postoperative surveillance is recommended after carotid artery reoperation.

Silent myocardial ischemia monitoring predicts late as well as perioperative cardiac events in patients undergoing vascular surgery.

In a previous study we have shown that perioperative monitoring for silent myocardial ischemia can noninvasively identify those patients undergoing peripheral vascular surgery who are at significantly increased risk for perioperative myocardial infarction. In the present study a group of 385 patients undergoing peripheral vascular surgery was studied long-term as well as short-term to determine whether perioperative monitoring for silent ischemia can identify those patients who are at significantly increased risk of late cardiac death or late cardiac complications as well as those patients at increased risk of perioperative myocardial infarction. All patients were monitored before, during, and after operation and were divided into two groups on the basis of results of monitoring: patients whose total duration of silent ischemia as a percentage of the total duration of perioperative monitoring was 1% or greater (group I, n = 120) and those for whom this value was less than 1% (group II, n = 265). Among patients in group I 13.3% (16 of 120) suffered a perioperative myocardial infarction in contrast to only 1.1% (3 of 265) patients in group II (p less than 0.001). Multivariate logistic regression analysis of preoperative and perioperative characteristics showed that the presence of a total perioperative percent time ischemic 1% or greater and age were the only significant predictors of perioperative myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Redo endarterectomy for recurrent carotid artery stenosis.

From a registry of 2406 carotid endarterectomies performed on 1818 patients over a 19-year period, 29 patients (1.6%) underwent reoperations for recurrent stenosis. Reoperations were performed for symptomatic stenosis for 23 and asymptomatic greater than 80% stenosis for six patients. Compared to the entire series, there was no difference in the incidence of restenosis for men and women. The pathologic findings were myointimal hyperplasia in 27%, atherosclerosis in 53%, thrombus with vessel dilatation in 17% and extrinsic scar in 3%. Redo endarterectomy with patch angioplasty was used for reconstruction in 27 patients and patch angioplasty alone in two. There were no operative deaths or strokes. Late follow-up (mean 50 months) revealed only one stroke and six other deaths. Although 21 (75%) were alive and stroke-free, follow-up studies suggest a high incidence (21%) of tertiary lesions among patients who have undergone redo endarterectomy for recurrent stenosis.

Vertebral artery angioplasty in patients younger than 55 years: long-term follow-up.

Since 1964 we have performed 136 vertebral artery reconstructions representing 4% of all operations on extracranial cerebral arteries by our staff. Fifteen of our patients were under age 55 years and had symptoms of dizziness, bilateral visual disturbances, ataxia, presyncopal episodes, and occasionally localized extremity weakness. Dizziness, often severe and incapacitating, has been the most common and consistent symptom. The diagnosis of vertebral artery lesions was made using aortic arch four-vessel cerebral arteriography. Operations were performed for severely obstructing bilateral vertebral artery lesions and included only unilateral vertebral vein patch angioplasty with or without suture plication of the artery in 13 patients. Unilateral carotid vertebral bypass was performed in one patient and unilateral vertebral reimplantation to the carotid in another. Follow-up averaged 8.9 years, ranging from ten months to 20 years. Eleven of 15 patients have remained asymptomatic and without strokes. Recurrent dizziness was present in three, two of whom had vertebral arteriography showing patent vertebral reconstructions. Another had a stroke related to the anterior circulation in follow-up at nine years. Atherosclerotic obstruction of vertebral arteries does occur in patients in the preatherosclerotic age group. Even atypical symptoms suggestive of vertebrobasilar insufficiency may be associated with isolated correctable bilateral flow-impeding vertebral lesions. These symptoms warrant evaluation with cardiac neurological and cerebrovascular studies. Vertebral angioplasty relieves symptoms and the incidence of stroke during follow-up is low.

Rupture of the vein patch: a rare complication of carotid endarterectomy.

Vein patch closure after carotid endarterectomy has been used to reduce the incidence of residual and recurrent stenosis at the carotid bifurcation. A rare but potential serious complication is rupture of the vein patch during the early postoperative period. In our experience of 2359 carotid operations performed from 1962 through 1986, saphenous vein was used for closure in 2275 (96.5%) operations. In three patients out of 75 in whom the vein patch had been harvested from the ankle, rupture of the patch occurred 2 to 5 days after uneventful carotid surgery. At emergency reoperation, the central portion of the vein was necrotic, with no evidence of infection. In each case the carotid artery was closed again with fresh thigh saphenous vein, and recovery was uneventful. The use of ankle vein was discontinued in December 1983 in favor of groin saphenous vein, and similar complications have not occurred in more than 600 carotid endarterectomies performed since. Early noninfectious ruptures of the saphenous vein patches have been mentioned in other reported series of carotid operations and have often been related to the use of ankle vein, but they remain unexplained.

The value of silent myocardial ischemia monitoring in the prediction of perioperative myocardial infarction in patients undergoing peripheral vascular surgery.

Real-time electrocardiographic monitoring for silent myocardial ischemia was performed on 200 patients undergoing peripheral vascular surgery to try to better define those at high risk of perioperative myocardial infarction. The patients were divided into those undergoing abdominal aortic aneurysm or lower extremity revascularization procedures (group I, n = 120) and those undergoing carotid artery endarterectomy (group II, n = 80). Silent ischemia was detected during the preoperative, intraoperative, or post-operative periods in 60.8% of group I and 67.5% of group II patients. Six group I and three group II patients suffered an acute perioperative myocardial infarction with two cardiac deaths. In both groups I and II a variety of parameters based on monitoring of silent myocardial ischemia were compared between the subgroups of patients who had myocardial infarction and those who did not. The results show that in both groups there was a significantly (p less than or equal to 0.05) greater total duration of perioperative ischemic time, total number of perioperative ischemic episodes, and total duration of perioperative ischemic time as a percent of total monitoring time in patients who suffered a perioperative myocardial infarction compared to those who did not. Multivariate logistic regression analysis of preoperative characteristics in all 200 patients showed the occurrence of preoperative silent myocardial ischemia and angina at rest to be the only significant predictors of perioperative myocardial infarction. Thus perioperative monitoring for silent myocardial ischemia might noninvasively identify those patients undergoing peripheral vascular surgery who are at increased risk for perioperative myocardial infarction, permitting implementation of timely preventive measures in selected patients.

Beta blockade to decrease silent myocardial ischemia during peripheral vascular surgery.

The incidence and duration of intraoperative silent myocardial ischemia have been shown to be significantly correlated with the incidence of perioperative myocardial infarction in patients undergoing peripheral vascular surgery. To assess the effectiveness of intraoperative beta blockade in limiting such silent myocardial ischemia, a group of 48 patients was treated with oral metoprolol immediately prior to peripheral vascular surgery. The total duration of intraoperative silent myocardial ischemia, the percentage of intraoperative time silent myocardial ischemia was present, the number of intraoperative episodes of silent myocardial ischemia, and the intraoperative heart rate in the treated patients were compared with those in 152 similar but untreated peripheral vascular surgery patients. The patients treated with oral metoprolol had significantly less intraoperative silent ischemia with respect to relative duration and frequency of episodes, a significantly lower intraoperative heart rate, and less intraoperative silent myocardial ischemia in terms of total absolute duration. These results suggest that beta-adrenergic activation may play a major role in the pathogenesis of silent myocardial ischemia during peripheral vascular surgery.

Is duplex scanning sufficient evaluation before carotid endarterectomy?

Recent reports have suggested that cerebral angiography may not be necessary before carotid endarterectomy is performed in selected patients. To determine if arteriography provides additional information that might influence the decision to operate or the conduct of the operation, a retrospective review was performed of 100 consecutive patients undergoing cerebral angiography and carotid duplex scanning. Eighty of the 100 patients subsequently underwent carotid endarterectomy for neurologic symptoms or asymptomatic stenosis greater than 80%. Among the 20 patients not operated on, three would have undergone unnecessary surgery for mistaken diagnoses had the arteriogram not been obtained. Two other patients in this group of 20 would have had carotid endarterectomy for asymptomatic stenosis in the presence of an equally stenotic tandem lesion. Among the 80 patients operated on, an additional three had the operative procedure altered because arteriographic studies revealed pathologic findings outside the area of duplex scan examination. Thus the use of arteriography altered the management of eight (8%) patients in this group of 100.