Causes of Perioperative Stroke after Carotid Endarterectomy: Special Considerations in Symptomatic Patients

Abstract

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.

Intraoperative Neurological Changes in 1665 Regional Anaesthetic Carotid Endarterectomies Predicts Postoperative Stroke

“…The only identified predictor of perioperative stroke and mortality in this series was intraoperative neurological change after carotid cross‐clamping, necessitating the placement of an intra‐arterial shunt. Whereas this finding confirms previous reports, these studies also purport that other factors such as preoperative stroke or contralateral carotid artery occlusion significantly increase the stroke risk 17,22,26,27 . Our large series does not support these claims, showing clamp intolerance and subsequent shunting to be a strong and the sole predictor.…”

“…Analysis showed that patient characteristics and comorbidities were not predictors. Traditionally, contralateral carotid artery occlusion has been considered a significant predictor of perioperative stroke and poor outcome 12,22 . Although our series showed that this was an important predictor of intraoperative neurological change necessitating shunting, the status of the contralateral carotid artery was unimportant in predicting perioperative stroke and death.…”

“…Patients with preoperative strokes were shown to have a lower rate than the other groups, although this was only a trend. The findings that neither the indication nor the contralateral artery are important in predicting stroke and mortality may be surprising given previous reports 14,22,25,26 . Nevertheless, it is reasonable to assume that predictors of shunting are not predictors of strokes.…”

Monocyte-Chemoattractant Protein-1 Levels in Human Atherosclerotic Lesions Associate With Plaque Vulnerability

“…Periprocedural strokes during carotid endarterectomy might have multiple causes but have been shown to frequently originate from plaque thrombosis and embolization. 48 Although the mechanisms underlying the observed associations remain unknown, they might relate to the higher risk of periprocedural microembolization previously reported to be more common in patients with features of vulnerable plaques. 27,49 To our knowledge, there has been only one small phase II trial targeting MCP-1 signaling in the context of human atherosclerosis.…”

Neurological complications of carotid revascularisation

“…Intraoperative thromboemboli occur during cross-clamping, arteriotomy, shunt placement and vessel closure by disrupting the atheromatous plaque, and stimulating local platelet activation and aggregation 28 30 31. In CAS, thromboemboli may arise as a result of plaque disruption at the site of intervention, protrusion of the thrombus through open cell stents with subsequent embolisation, or more proximally from the aortic arch during device introduction 32.…”