Gary Giangola

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.

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

Abstract 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.

Intracranial hemorrhage after carotid endarterectomy

Among 1500 carotid endarterectomies performed between 1975 and 1984, 11 ipsilateral intracranial hemorrhages (IH) occurred between the first and tenth postoperative days for an incidence of 0.7%. The mortality rate among these patients was 36%. The only recognizable predisposing factor was relief of high-grade carotid stenosis (greater than 90%) whereas other factors such as age (58 to 81 years), preoperative hypertension (systolic blood pressure 120 to 160 mm Hg), preoperative head CT scans showing recent infarction (only one in five positive), and preoperative cerebral infarction (only 1 of 11 patients) did not play a role. All patients had normal coagulation studies. No patient required a shunt because all tolerated cross-clamping of the carotid artery. Postoperative systolic blood pressures were 200 to 240 mm Hg in 6 of 11 patients. The time of occurrence of IH extended from the immediate postoperative period to the tenth postoperative day (mean interval 3.3 days). Treatment consisted of craniotomy in five patients; four survived and one recovered completely. Of the six patients treated nonoperatively, three survived and two completely recovered. IH shares equal incidence with recurrent thrombosis, cross-clamping ischemia, and embolization as a cause of perioperative stroke. Although all except IH can be prevented by current practice, the means of preventing IH are not apparent; however, careful monitoring of blood pressure to prevent uncontrolled hypertension deserves consideration.

Natural history and management of the asymptomatic, moderately stenotic internal carotid artery

PURPOSE Although it has been widely accepted as the evidence supporting prophylactic carotid endarterectomy, aspects of the Asymptomatic Carotid Atherosclerosis Study have left unease among clinicians who must decide which individuals without symptoms should undergo surgery. Additional confusion has been created by the fact that the several large randomized trials investigating the efficacy of carotid endarterectomy have classified and analyzed different categories of carotid stenosis. In an effort to provide more information on the natural history of asymptomatic, moderate carotid artery stenosis (50% to 79%), we have reviewed data on approximately 500 arteries. METHODS Records of our vascular laboratory from 1990 to 1992 were reviewed. We identified 425 patients with asymptomatic, moderate carotid artery stenosis; 71 patients had bilateral stenoses in this category, resulting in 496 arteries for study. RESULTS The mean length of follow-up was 38 +/- 18 months. New ipsilateral strokes occurred in 16 (3.8%) patients. New ipsilateral transient ischemic attacks occurred in 25 (5.9%) patients. Documented progression of stenosis occurred in 48 (17%) of the 282 arteries for which a repeat duplex examination was available. Arteries that progressed to > 80% stenosis were significantly more likely to have caused strokes than those that remained in the 50% to 79% range (10.4% vs 2.1%, p < 0.02). Conversely, arteries that remained stable in the degree of stenosis were significantly more likely to have remained asymptomatic than those that progressed (92.7% vs 62.5%, p < 0.001). With life-table analysis the estimated cumulative ipsilateral stroke rate was 0.85% at 1 year, 3.6% at 3 years, and 5.4% at 5 years. The respective estimated cumulative transient ischemic attack rates were 1.9%, 5.5%, and 6.3%. The respective estimated cumulative rates for progression of stenosis were 4.9%, 16.7%, and 26.5%. Life-table comparison of ipsilateral stroke revealed a significantly higher cumulative rate among arteries that progressed in the degree of stenosis than among those that remained stable (p < 0.001). CONCLUSIONS Based on the low rate of permanent neurologic events in these cases, prophylactic carotid endarterectomy for the asymptomatic, moderately stenotic internal carotid artery cannot currently be recommended. The only factor that appears to predict increased risk for future stroke is progression of stenosis. Careful follow-up with serial repeat duplex examinations must be performed in these patients. Until there are widely accepted duplex parameters that can provide all clinicians with accurate identification of arteries with narrowing corresponding to 60% stenosis as defined by the Asymptomatic Carotid Atherosclerosis Study, all surgeons will need to be aware of specifically how their noninvasive laboratories are deriving their results. For the many laboratories that continue to use the University of Washington criteria, 80% should remain the level above which prophylactic carotid endarterectomy is warranted.

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.

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.

Redo carotid surgery: An analysis of materials and configurations used in carotid reoperations and their influence on perioperative stroke and subsequent recurrent stenosis

OBJECTIVE The ideal method of arterial reconstruction in operations for recurrent carotid disease after prior endarterectomy is unknown. The goal of this study was to review a series of carotid reoperations and to determine whether the surgical technique influenced the rate of perioperative stroke, late stroke, or secondary restenosis. METHODS A retrospective review was conducted of 82 carotid reoperations performed on 74 patients at our institution. RESULTS The patient population included 39 men (52.7%) and 35 women (47.3%), with a mean age of 67.5 years. The indications for redo surgery included transient ischemic attack or amaurosis fugax in 35.3% of the patients, stroke in 6.1%, and asymptomatic restenosis (>80%) in 58.5%. Patch angioplasty with or without redo endarterectomy was used in 47 cases (57.3%), with saphenous vein in 26 (31.7%), Dacron in 15 (18.3%), and polytetrafluoroethylene in 6 (7.3%). Interposition grafting was used in 35 cases (42.7%), with saphenous vein in 9 (11.0%), Dacron in 10 (12.2%), and polytetrafluoroethylene in 16 (19.5%). The perioperative complications included three strokes (3.7%). There was a trend toward increased perioperative neurologic complications with interposition grafting when compared with patch angioplasty (8.6% vs 2.1%), although this did not reach statistical significance. Long-term clinical follow-up was obtained in all cases with a mean duration of 35 months, with follow-up duplex scanning performed in 89.2%. The late failures of redo surgery included four significant secondary restenoses and five total occlusions. There was a trend towards improved long-term results with interposition grafting as opposed to patch angioplasty. However, the cases in which reconstruction was performed with a vein had a significantly higher rate of late failures (stroke, secondary recurrent stenosis, or occlusion) than those in which reconstruction was performed with any prosthetic material (26.7% vs 2.3%; P =.002 by Fisher exact test). CONCLUSION The use of autologous material for redo carotid surgery in any configuration appears to significantly increase the rate of subsequent recurrent stenosis or total occlusion of the operated artery. The reason for this finding is unclear but may be related to both host and technical factors. Prosthetic material may be more durable in the long-term for redo carotid surgery. Interposition grafting for redo carotid surgery may increase the perioperative neurologic complication rate to some degree; however, this was not statistically significant in this series. Interposition grafting may be a more durable solution in long-term follow-up than redo endarterectomy and patch angioplasty. A longer follow-up period will be needed to confirm this conclusion.

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.

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)