Ronnie Landis

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.

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.

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.

A model for predicting occult carotid artery stenosis: screening is justified in a selected population

OBJECTIVES The diagnosis and treatment of carotid artery disease is an integral part of stroke prevention. However, a population of patients who would benefit from screening for carotid artery stenosis has not been well defined. As part of an institutional stroke-screening program, a modified, rapid duplex scan was developed to evaluate patients for occult carotid stenosis. The goal of this study was to evaluate risk factors predictive of carotid stenosis in a selected population, and to identify patients who would benefit from carotid screening. METHODS Patients were eligible for the study if they were >60 years of age and had a history of hypertension, heart disease, current smoking, or family history of stroke. A modified carotid duplex scan that had been previously validated against formal duplex scanning was utilized; this involved visualization of the carotid bulb and proximal internal carotid artery where Doppler flow velocities were obtained and recorded. RESULTS Screening was performed on 394 patients. Thirty-eight patients (9.6%) had either unilateral or bilateral carotid stenosis of > or =50%. Risk factors evaluated included smoking, hypertension, cardiac disease, or hypercholesterolemia. If none of these risk factors was present, the incidence of carotid stenosis was 1.8%. This increased to 5.8% with one risk factor, 13.5% with two risk factors, and 16.7% with three risk factors. Two of three patients with all four risk factors had carotid stenosis (66.7%). Logistic regression and prespecified contrast statements for multiple comparisons were used to assess the relationship between the presence of risk factors and occult carotid artery stenosis. The presence of any one of these risk factors was associated with a statistically significant increase in the presence of occult carotid stenosis (P <.01). This was also statistically significant for the presence of any two risk factors (P <.01) or three risk factors (P <.05). CONCLUSION The prevalence of carotid stenosis significantly increases with the presence of one or more identifiable demographic risk factors in a selected population. Assuming the diagnosis and treatment of carotid stenosis are fundamental to stroke prevention, screening for carotid artery disease is justified in this group of patients.

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.

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)

A Comparative Study of Saphenous Vein, Internal Jugular Vein, and Knitted Dacron Patches for Carotid Artery Endarterectomy

To determine whether the choice of material used for patch closure following carotid artery endarterectomy (CAE) affected the immediate operative results, the early follow-up results, or the incidence of early restenosis, a retrospective study of 275 consecutive carotid endarterectomies by two vascular surgeons was performed. Among 275 primary CAEs performed between July 1991 and August 1993, 159 (57.8%) were closed with saphenous vein (SV), 25 (9.1%) with double-thickness internal jugular vein (JV), and 91 (33.1%) with knitted Dacron (KD). Primary closure was not used in any of the arteries in this series. The overall perioperative mortality rate was 1.1% and the rate of major and minor morbidity was 4.4%. There were four (1.5%) perioperative strokes: two (1.3%) in the SV group, one (4.0%) in the JV group, and one (1.1%) in the KD group. Two-hundred fifty-eight (93.8%) of the 275 endarterectomies were followed postoperatively for 2 to 35 months (mean 14.4). Two-hundred nineteen (79.6%) were evaluated using duplex scans during follow-up with a mean interval of 13.7 months. Of the arteries studied, four (3.6%) in the SV group, none in the JV group, and six (8.4%) in the KD group demonstrated restenosis of >50% at the time of follow-up (NS). In addition, one (0.9%) artery in the SV group, one (5.6%) in the JV group, and none in the KD group demonstrated complete occlusion. Retrospective analysis of the data showed no statistically significant differences in perioperative morbidity, mortality, or early postoperative restenosis whether the artery was closed with saphenous vein, jugular vein, or knitted Dacron patches. Longer follow-up is needed to determine whether rates of late restenosis and aneurysmal dilatation will differ between synthetic and autologous patches.

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 clamptolerant patients. Technical precision and appropriate cerebral protection are particularly critical for successful outcomes in high-risk patients.

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.

Should proximal saphenous vein be used for carotid patch angioplasty: a clinical study of the need for vein in subsequent operations.

Reluctance to use saphenous vein (SV) for patch closure of the carotid arteriotomy is due in part to the concern of vascular surgeons that the SV should be preserved for possible future coronary or lower extremity reconstruction. Even among those who favour vein patch closure of the arteriotomy for improved immediate and late results, an effort has been made to use the ankle portion of the SV, preserving the upper, larger segment for later surgery. Recent reports of rupture of the patches formed from ankle SV and a study showing a decrease in strength of the ankle segment of vein, raised the question of the importance of trying to preserve the proximal SV and the impact of use of this segment in those patients requiring secondary vascular procedures. We reviewed 134 consecutive carotid patients from 1981 who had proximal SV harvested for patch angioplasty. Of those 122 were available (mean 44.9 months). Thirteen had secondary vascular procedures. Adequate saphenous vein was available in twelve. We conclude from this study that (1) less than 15% of patients undergoing carotid surgery will require a secondary vascular surgery within 5 years and (2) harvesting SV from the thigh rarely compromises future revascularisation.