Carotid endarterectomy, 1982--the state of the art

Surgical Techniques from Intraoperative Angiographic and Velocimetric Controls in 43 Consecutive Carotid Bifurcation Endarterectomies

From January to November, 1985, 43 carotid bifurcation endarterectomies (CE) were performed with intraoperative functional (Doppler spectrum analy sis) and morphologic (angiography) controls.

In the first 20 cases, after thromboendarterectomy and direct suture, Dop pler showed absence of or no significant variations of frequency in 17 cases, a frequency increase corresponding to a less than 45% diameter reduction steno sis at the apex of the suture in 2 cases, and no flow in the internal carotid artery (ICA) in 1 case. Angiography confirmed the thrombosis in the above mentioned case and showed 3 less than 50% stenoses at the distal end of the arteriotomy: 2 already recognized by Doppler in small-size ICAs and 1 in a medium-size ICA without significant changes of flow. The reason for thrombosis was a distal intimal flap, which was successfully removed; the 2 stenoses in which Doppler and angiography agreed were corrected by patch angioplasty. In the last 23 cases, patch angioplasty was performed routinely in small-size ICAs (6 cases); in 1 case, first treated by a direct suture, Doppler and angiography showed a medium-grade stenosis, immediately corrected; in 1 case both techniques showed a 50% stenosis in a common carotid artery, immediately corrected. The execution of intraoperative angiography in this group of patients al lowed the authors to define the indication for the use of patch angioplasty, never previously employed. Nevertheless, the authors state that, on account of loss of time, costs, and exposure to radiations, intraoperative angiography must be reserved for those cases selected by Doppler spectrum analysis. This method seems to be highly sensitive in recognizing significant technical defects that could lead to an immediate or late failure.

Bispectral index monitoring may not reliably indicate cerebral ischaemia during awake carotid endarterectomy † †This study was conducted in the Department of Neurosurgery, Newcastle General Hospital, Newcastle Upon Tyne NE4 6BE, UK. Preliminary results were presented at the British Neurosurgery Research Group Meeting, Sheffield, March 29–30, 2001

BACKGROUND

Intraoperative ischaemia during carotid cross-clamping in patients undergoing carotid endarterectomy (CEA) is a major complication and prompt recognition of insufficient collateral blood supply is crucial. Electroencephalogram (EEG) is believed to be one of the useful forms of monitoring cerebrovascular insufficiency during CEA. The aim of this study was to evaluate the utility of bispectral index (BIS) monitoring, a processed EEG parameter, for the reliable detection of intraoperative cerebral ischaemia during awake CEA.

METHODS

We monitored 52 patients continuously with the BIS monitor together with assessment of neurological function (contralateral upper and lower limb strength and the verbal component of the Glasgow Coma Scale for speech) in patients undergoing awake CEA.

RESULTS

Overall mean BIS value in all patients was 96 (SD 2.9). In five patients who showed clinical evidence of cortical ischaemia during carotid cross-clamping, there was no change in the original range of BIS values throughout the procedure (96.7 [3.2]). In one patient BIS values decreased to 38 about 5 min after the incision and recovered within the next 10 min. The mean BIS value in the remaining 46 patients who did not develop clinical signs of ischaemia was 95.4 (2.6). Three cases are presented which demonstrate the inability of the BIS monitor to detect cerebral ischaemia.

CONCLUSIONS

Lack of correlation of BIS with the signs of cerebral ischaemia during CEA makes it unreliable for detection of cerebrovascular insufficiency. We conclude that awake neurological testing is the preferred method of monitoring in these patients.

Influence of patient-related variables on the outcome of carotid endarterectomy

PURPOSE

Variability in outcome after carotid endarterectomy is well recognized. This study examines the importance of patient-related factors in determining outcome.

METHODS

Four hundred and sixty consecutive patients undergoing carotid endarterectomy for symptomatic severe (60% to 99%) internal carotid stenosis performed by one vascular surgeon have been studied prospectively. Patients were followed-up at 3, 6, 9, and 12 months and then yearly. Pre-, intra-, and perioperative details and follow-up information were entered on a database.

RESULTS

Multiple logistic regression identified a number of factors significantly associated with death and stroke. A history of crescendo transient ischemic attacks (TIAs) (p = 0.003, p = 0.0002) and being female (p = 0.03, p = 0.0001) were associated with both perioperative death and stroke within 30 days of operation, respectively. Deaths between 1 and 36 months were associated with ischemic heart disease (p = 0.03) and diabetes (p = 0.04), whereas stroke was associated with small internal carotid diameter (p = 0.02). The importance of symptoms at presentation on outcome was further emphasized by life-table analysis. In 98% of patients with amaurosis fugax, only 67% of those with crescendo TIAs were alive at 18 months (p < 0.01). The survival of patients with amaurosis was significantly better than those with TIAs (p < 0.01), transient stroke (p < 0.01), and progressive, stroke (p < 0.05). Similarly, postoperative stroke was significantly more common for patients with crescendo TIAs than those with amaurosis (p < 0.01), established stroke (p < 0.05), and TIA (p < 0.05). Transient stroke was associated with a poor outcome, with only 66% of patients being alive in 36 months and 14% having suffered a stroke (p < 0.05 compared with established stroke).

CONCLUSION

Presenting symptoms significantly predict outcome after carotid endarterectomy. This should be considered both in patient selection and comparison of patient series.

A systematic review of the risks of stroke and death due to endarterectomy for symptomatic carotid stenosis

BACKGROUND AND PURPOSE

Carotid endarterectomy reduces the risk of carotid territory ischemic stroke ipsilateral to a recently symptomatic severe carotid stenosis. However, the benefit is limited by the risks of stroke and death associated with the operation. Although reported surgical risks vary enormously, there has been no systematic review of the published literature.

METHODS

We performed a systematic review of mortality and the risk of stroke and/or death due to endarterectomy for symptomatic carotid stenosis in studies published since 1980.

RESULTS

Fifty-one studies fulfilled our criteria. Overall mortality was 1.62% (95% confidence interval [CI], 1.3 to 1.9), and the risk of stroke and/or death was 5.64% (95% CI, 4.4 to 6.9). However, there was significant heterogeneity of risk of stroke and/or death (P < .001). The risk varied systematically with the methods and the authorship of the study. The risk of stroke and/or death was highest in studies in which patients were assessed by a neurologist after surgery (7.7%; 95% CI, 5.0 to 10.2) and lowest in studies with a single author affiliated with a department of surgery (2.3%; 95% CI, 1.8 to 2.7). After correcting for study methodology, there was no temporal trend in the risk of stroke and/or death between 1980 and 1995.

CONCLUSIONS

The reported risks of endarterectomy for symptomatic carotid stenosis show significantly greater variability than would be expected by chance. However, much of this variability can be accounted for by differences in methodology and authorship. The 5.6% overall risk of stroke and/or death is consistent with present guidelines.

Asymptomatic carotid stenosis: a benign lesion?

Recent reports of the risk of asymptomatic carotid stenosis have been compromised by flawed patient selection or the performance of a large number of carotid endarterectomies during follow-up. We report the natural history of a randomly selected group of asymptomatic patients (n = 188; 114 males and 74 females) with documented carotid artery disease who were prospectively followed without intervention for up to 8 years. Risk factors included ischaemic heart disease in 17%, diabetes in 10%, hypertension in 46% and 88% were smokers. The degree of internal carotid stenosis was classified by duplex scanning and a total of 259 vessels had evidence of atherosclerosis. Study end-points included TIA, CVA and death. At mean follow-up of 4 years 3% of the 96 patients with internal carotid artery stenosis of less than 50% had died and 2% suffered a stroke. Six per cent of patients with a stenosis of 50-79% had died and 4% and 2% had suffered a CVA and TIA, respectively. In the 59 patients with greater than 80% stenosis 7% had suffered a TIA and an additional 7% a CVA, while 2% had died. None of the patients suffering a stroke had an antecedent TIA. Though the incidence of ischaemic events is significantly higher in patients with greater than 80% stenosis the incidence of unheralded stroke remains low. We therefore continue to recommend a conservative approach to the management of asymptomatic carotid stenosis.

Blowout of carotid venous patch angioplasty

Two cases of vein patch blowout were observed five and seven days after carotid bifurcation endarterectomy with patch angioplasty. Both patients died in spite of emergency reoperation. One patient developed respiratory failure with subsequent fatal cardiac arrest seven days after reoperation; the other died of extensive hemispheric infarction on the fifth postoperative day. At reoperation both ruptures were found to be located in the middle of the patch whereas the suture lines were intact. Both patients were hypertensive. In the first case, an accessory saphenous vein retrieved from the calf had been the only venous material available for the patch, while the other patient had varicose veins in the contralateral leg. Pathology revealed central transmural tissue necrosis in one of the disrupted patches. A review of the literature regarding morphologic alterations of free vein grafts placed within the arterial circulation as well as hemodynamics in patched arterial segments may provide additional insight as to the inherent benefits and risks of vein patch angioplasty after carotid endarterectomy. When considering vein patch angioplasty, particular attention should be directed to the gross aspect of the vein to be used as well as to any antecedent history of phlebitis.

Effects of Furegrelate (Upjohn 63557A) on patency and platelet deposition after canine carotid endarterectomy

Platelet deposition upon endarterectomy sites is a likely cause for early postoperative thrombosis, embolism and restenosis. Platelets aggregate by the thromboxane-prostacycline mechanism. Thromboxane synthetase inhibitors which have been safely administered to humans should reduce platelet deposition after surgical therapy and therefore reduce peri-operative mortality and the prevalence of stroke. A randomized prospective controlled trial was designed to determine vessel patency and platelet deposition associated with the use of 3 mg/kg and 30 mg/kg of Furegrelate (Upjohn U63557A) daily in dogs, who were to have carotid endarterectomy. The 46 treated and 46 control dogs had total carotid patency of 96% and 76% respectively (P less than 0.01). Fourteen dogs treated with 30 mg/kg Furegrelate had no occlusions, compared with a 19% prevalence in 13 controls (P less than 0.02). Furegrelate 10 mg/kg significantly lowered platelet aggregation. Platelet deposition was not significantly changed, however. The reason for this disparity was a probable persistence of vessel wall factors which promoted platelet deposition. This approach might therefore lower rates of peri-operative thrombosis but it would be very unlikely to alter the incidence of restenosis or embolism. Further research could be directed towards modifying the stimuli for platelet deposition upon the endarterectomy site.

Carotid endarterectomy in a community hospital: a change in physicians' practice patterns

A total of 243 consecutive carotid endarterectomies (CEA) performed at Providence Medical Center in Portland, Oregon, were retrospectively reviewed over a 22-month period. Of these, 137 patients (56%) underwent CEA for asymptomatic disease, 52 (37%) of whom had stenotic lesions of 79% or less. There were 6 deaths (3%) and 12 strokes (5%). Four strokes were in asymptomatic patients. These data prompted development of criteria for CEA: (1) hemisphere-specific transient ischemic attacks, reversible ischemic neurologic deficits, or amaurosis fugax with an appropriate carotid lesion; (2) completed stroke with major recovery and significant carotid stenosis; (3) asymptomatic lesion with greater than 80% stenosis (D+) either by carotid arteriogram or non-invasive lab evaluation; and (4) other indications only with a supporting second opinion from a disinterested vascular surgeon, neurosurgeon or neurologist. A prospective review followed institution of the guidelines. In 21 months, 148 operations were performed, a 36% reduction over the initial study period. Of these, 46 (31%) were for asymptomatic lesions. Two patients (4%) did not fulfill the guideline criteria. There were six strokes (4%) and no deaths. The reduction of CEAs appears to be related to a significant decrease in "inappropriate" operations being performed. Surgeons' familiarity with the data rather than external pressures seems to be the major factor in changing practice patterns. The decrease in stroke/death rate is not statistically significant.

Risk factors for intra-operative neurological deficit during carotid endarterectomy

Although embolism is considered to be the major cause of intra-operative neurological deficit (IOND) during carotid endarterectomy, the possibility that patients may vary in susceptibility to ischaemic damage following minor embolisation or falls in cerebral perfusion pressure is rarely considered. A prospective study was undertaken in 60 consecutive patients undergoing carotid endarterectomy to identify risk factors for IOND. The hypothesis was that patients with impaired cerebral vascular reserve (CVR) may be more vulnerable to intra-operative emboli or falls in cerebral perfusion pressure than normal subjects. Recent work using Positron Emission Tomography has indicated that the best index of CVR is the ratio of cerebral blood flow to cerebral blood volume, which is another expression for the reciprocal of mean cerebral transit time (MCTT). In this study, a new isotopic method of quantifying MCTT was used to identify patients with impaired CVR. Six patients (10%) recovered from anaesthesia with an IOND, only one of which was disabling. Significant risk factors for IOND were: (i) age over 65 years (Odds Ratio 13.0 (95%CI 1.4-121), p = 0.013); (ii) a residual neurological deficit prior to operation (Odds Ratio 7.0 (95%CE 1.1-43), p = 0.038); (iii) complex plaque morphology (Odds Ratio 6.4 (95%CI 1.06-34), p = 0.046); and (iv) the combination of impaired CVR and a CT scan infarct in the symptomatic hemisphere (Odds Ratio 9.8 (95%CI 1.5-62), p = 0.026). These observations suggest that certain risk factors for IOND can be identified preoperatively and this may enable a more discriminating approach to patient selection for operation and a more critical evaluation of operative technique and methods for intra-operative protection and monitoring in the future.

Pre- and intraoperative transcranial Doppler: prediction and surveillance of tolerance to carotid clamping

We report 91 patients (mean age 70 years) operated upon, prospectively for a total of 100 carotid revascularizations (nine bilateral). Eighty-five of these patients had pre-, intra-, and postoperative transcranial Doppler investigations. Preoperatively, these 85 patients (92 procedures) were classified into two groups based on the results of their Doppler examinations: Group A (65 patients, 72 procedures), those who did not require an intraoperative indwelling shunt and Group B (20 patients, 20 procedures), those who did. The shunt was inserted only when the mean stump (back) pressure was less than 50 mmHg after cross-clamping. Group A all had satisfactory collaterality with a functional anterior and one or two posterior communicating arteries. Group B had no communicating arteries (anterior or posterior) identified by transcranial Doppler. In 17 of 20 patients in this group, the stump pressure was less than 50 mmHg and a shunt was placed. The overall prediction based on Doppler examination of whether or not patients would need a shunt during operation for the two groups A and B (i.e., 92 procedures) was correct in 95.6% (88/92) of cases. Moreover, six hemodynamically significant stenoses (four in the cavernous portion, two in the middle cerebral artery) were disclosed. Sensitivity and specificity of transcranial Doppler as correlated with arteriographic findings were 70 and 90%. Preoperative transcranial Doppler can measure the velocities of the principal cerebral arteries and the collateral capacity of the circle of Willis, and can forecast tolerance to carotid cross-clamping. Intraoperatively, the velocity of flow in the middle carotid artery was correlated with stump pressure, which allowed for surveillance of the shunt.

Comparison of the processed electroencephalogram and awake neurological assessment during carotid endarterectomy

A processed electroencephalogram (EEG) produced by the Lifescan monitor (Neurometrics), was compared to awake neurological assessment for detecting cerebral ischaemia in seventy patients undergoing carotid endarterectomy under cervical plexus block. Of the six patients demonstrating neurological signs on cross-clamping the carotid, five displayed simultaneous EEG changes, four being detected during surgery, and one being detected after reviewing the EEG postoperatively. Another four patients displayed EEG changes indicative of ischaemia but unassociated with neurological signs. A further patient displayed contralateral intraoperative EEG changes. Hypotension resulted in one EEG change and two cases were associated with technical difficulties with the monitor. The presence of false negatives, possible false positives, technical errors and subjective interpretation associated with the processed EEG make it less reliable than awake neurological assessment for the detection of cerebral ischaemia.

Surgical treatment of extracranial cerebrovascular disease: regional experience

This paper reports a retrospective review of 40 patients who underwent 48 surgical procedures to treat extracranial cerebrovascular disease. The surgery was performed at the Port Kembla District Hospital (a 145-bed regional institution) between 4 October 1984 and 9 September 1987. Carotid endarterectomy was the most common operation (n = 44, 91.6%). The survey reports the patterns of presenting symptoms, risk factors, investigations, surgical detail and early and late complications, and compares these with other published series. Operative and peri-operative morbidity and mortality were within contemporary international standards: mortality 0% (reference range: 0-1%); stroke 2.1% (1-3%); transient ischaemic attack 6.3% (0-8%). These results support the contention of other authors that international standards for extracranial cerebrovascular surgery are achievable in regional institutions.

The course of atherosclerotic diseases after carotid endarterectomy in 279 patients followed-up for 21 years

Two hundred and seventy-nine patients underwent 331 consecutive carotid endarterectomies during a 20-year period from 1965 to 1984 and were followed-up for 21 years (median 76.0 months). The procedure-combined mortality was 3.9% (13 out of 331 patients). The mortality was 2-3% during the first 3 years, 4-6% from the fourth to the seventh year, and 9-10% per year thereafter. Late deaths (n = 101) were caused by coronary heart disease (CHD) in 51% by cerebrovascular disease (CVD) in 17% and by other causes in 32% of the cases. The ratio of CHD to CVD deaths, 3:1, is similar to a normal population. The possibility of dying in a cerebrovascular accident is six-fold in untreated patients when compared to the results in this study. The combined incidence of fatal and non-fatal strokes during the first and fifth year was 3%, and otherwise 1-2%. The other manifestations of atherosclerosis, CHD, and peripheral arterial occlusive disease were combined with CVD in 68.5% of the cases. The frequency of CHD was significantly combined with elevated serum triglyceride, and apolipoprotein B concentrations, decreased serum high density lipoprotein cholesterol concentrations at the control examination, and frequency of hypertension. Therefore, it would be important to follow such patients and reduce the risk factors of CHD.

The use of aperiodic analysis of the EEG during carotid artery surgery

A new processed EEG machine, the Lifescan, which uses aperiodic analysis, was used to monitor cerebral activity prospectively in twenty-one patients undergoing carotid artery surgery under general anaesthesia. The machine was easy to apply, use and read. Volatile agents caused a bilateral decrease in high frequency activity. Unilateral changes consistent with cerebral ischaemia at the time of carotid cross-clamping were also seen. One such prolonged change was not associated with neurological deficit. A further patient awoke with neurological deficit without displaying Lifescan evidence of ischaemia. The machine requires further assessment.

Therapy for isolated, low and high grade symptomatic carotid artery stenosis

This study evaluates whether medical therapy alone can achieve satisfactory results in the treatment of low grade carotid stenosis or ulcerated plaques. Out of 525 patients presenting with transient or minor strokes, 64 were found with unilateral extracranial vascular disease as the sole potential source for their neurological symptoms. Utilizing arteriographic criteria, 35 patients with ulcerated plaques or carotid artery stenosis of less than 50% luminal artery diameter were treated conservatively with aspirin and dipyridamole (300 mg/day each). Twenty-nine patients with unilateral internal carotid artery stenosis of greater than 50% luminal artery diameter were treated by means of carotid endarterectomy. Follow-up in the two groups for a mean period of 24-26 months revealed no major strokes or neurological deaths in either group. Myocardial infarction was the major cause of death. Two patients developed subsequent transient ischemic attacks, and one a minor stroke with total recovery in the conservatively treated group. All became asymptomatic when warfarin replaced aspirin therapy. The findings in this study confirmed that "low grade" stenoses can be safely treated by medical measures alone.

Cerebral angiography for cerebrovascular disease: the risks

Cerebral angiography is still suggested as a first line investigation for patients with putative transient ischaemic attacks (TIA) and it is considered by most surgeons as a necessary prelude to carotid endarterectomy. That conventional cerebral angiography involves risk is well known, although the magnitude of this risk is not. Prospective studies of cerebral complications from this technique, published over the last decade, have been analysed to show that the major stroke rate after conventional cerebral angiography for patients with TIAs is likely to be about 2.4 per cent. This must be taken into account if the true morbidity of carotid endarterectomy is to be appreciated (assuming conventional angiograms have been used). Furthermore, since many sufferers are assessed by angiography but not submitted to surgery, a policy of conventional angiography for patients with TIAs puts a far greater number at risk than that actually having carotid endarterectomy.

Long-term results after carotid artery surgery

This study presents the results from a follow-up after 414 carotid reconstructions performed on 352 patients during the years 1971-82. At the end of the follow-up period 267 patients were alive (75.8%) and 253 patients remained asymptomatic. The median follow-up time was 35 months (6 months-12 years). Patients with coronary artery disease (CAD) had a significantly lower survival than patients without signs of CAD. Coronary artery disease was significantly more frequent among patients with bilateral carotid lesions compared to patients with unilateral lesions. The actuarial stroke frequency, operative morbidity included, on the operated side was 2.5%/year. However, from 6 months postoperatively up to 8 years the stroke frequency was 1%/year. In the stroke frequencies all neurological deficits of more than 24 h duration are accounted for. Although there was a trend toward higher stroke rates among older patients there were no significant differences between age groups. Assuming a 10% stroke frequency during the first year after a TIA and a 6% annual stroke rate thereafter our results would cross even such a natural course curve at 18 months.

Risk factors in carotid artery surgery: an evaluation of 414 operations

Four hundred and fourteen carotid reconstructions performed on 352 patients during the years 1971-82 were analysed retrospectively. Fifty-eight percent of the patients were operated on because of hemispheric transient ischaemic attacks (TIA). Twenty-eight percent had suffered a stroke before surgery. The overall combined mortality and morbidity was 7.7%. The procedure mortality was 2.9% with a slightly higher mortality i.e. 5.9% in the stroke group although not significantly higher than among non-stroke patients with a mortality of 1.4%. Patients of more than 70-years had a significantly higher operative mortality (11.1%) than the rest of the patients (1.7%). Non-fatal strokes occurred in 20 patients (4.8%). No correlation was found with the degree of stenosis of the contralateral artery.

Prospective assessment of carotid endarterectomy by clinical and ultrasonic methods

Sixty-three carotid endarterectomies in 60 patients were followed by clinical and duplex scanning at 2 weeks postoperatively and at 3-monthly intervals for 3 years (mean 18 months). Four patients died (two of stroke, two of myocardial infarction) and four survivors had recurrent ipsilateral symptoms. Two had an immediate mild hemiparesis which recovered completely within 36 h; in both, the endarterectomized arteries were patent on scanning. The other two experienced amaurosis fugax for 2-3 weeks at 2 and 24 weeks; scanning showed that the sites of both endarterectomies had become occluded. Ultrasound assessment at 2 weeks showed that 43 of 61 (70.5 per cent) endarterectomized arteries were widely patent. There were three occlusions, one stenosis of greater than 75 per cent, three stenoses of greater than 50 per cent and eleven stenoses of less than 50 per cent. At 6 months a total of five vessels were occluded, with greater than 75 per cent stenosis in three and greater than 50 per cent stenosis in eight. At latest follow-up, six of eight arteries with greater than 50 per cent stenosis shown earlier had scans which had reverted to normal. Tacking down of the distal intima was associated with higher incidence of restenosis and occlusion (P less than 0.01). Women were more predisposed to restenosis by neointimal hyperplasia (P less than 0.05). All restenosis occurred within the first 6 months postoperatively (26.2 per cent) and fell to 16.4 per cent at the end of the study.

Carotid endarterectomy: factors influencing perioperative complications

Early carotid surgery has been suggested to be an important cause of perioperative deterioration due to secondary haemorrhage into a recent brain infarction. It has also been suggested that the existence of preoperative neurological deficits may worsen the prognosis of surgical treatment in carotid disease. Neither of these observations could be confirmed; severe perioperative complications (5%) in this study of carotid endarterectomy were strongly related to the degree of carotid stenosis. This aspect of carotid surgery has not been previously studied. Even though technical difficulties may play an exaggerated role in a training hospital system, it is nevertheless necessary to assess the impact of surgical procedures of different extent when the "acceptable risk" for carotid surgery is calculated.

Carotid endarterectomy in Great Britain and Ireland

A survey of the practice of carotid surgery by 245 vascular and neurological surgeons in Great Britain and Ireland was conducted with a 96 per cent response. Ninety-six surgeons (41 per cent) performed at least one carotid endarterectomy in 1984 and a total of 1374 such operations were carried out in that year. The indications for carotid endarterectomy in order of frequency were transient ischaemic attack, minor stroke and stroke. Operation was hardly ever undertaken for asymptomatic carotid bruit. Eighty-six per cent of surgeons who performed carotid endarterectomy generally assessed patients in the first instance using techniques less invasive than conventional angiography, principally Doppler ultrasonography or digital subtraction angiography. Nevertheless, conventional angiograms were usually performed before surgery by 89 per cent of surgeons. Almost all surgeons operated only under general anaesthesia, while opinion on the use of an intraluminal shunt during carotid endarterectomy was divided. Despite an increase in the number of carotid endarterectomies in recent years, this operation is currently performed nineteen times less frequently in Great Britain and Ireland than in the USA. The reasons for this are explored and certain controversies surrounding carotid endarterectomy are discussed.

Prevention of early restenosis and thrombosis-occlusion after carotid endarterectomy by saphenous vein patch angioplasty

The hypothesis that saphenous vein patch angioplasty protects against early postoperative restenosis and thrombosis-occlusion was tested by comparing the clinical outcome and carotid artery status of 100 carotid endarterectomies with and 100 without saphenous vein patch angioplasty performed by a single surgeon over a 30-month period. The patient population, selection, perioperative management, and the technical aspects of the operation, except for the vein patch, were essentially identical in both groups. Carotid artery status was assessed by direct continuous wave Doppler and Gee OPG at three to six months and again at one year postoperatively. There were two hospital deaths, both in the nonpatched group, one cardiac and the other neurologic due to internal carotid thrombosis. Two reversible neurological deficits due to thrombosis and one due to restenosis occurred in the non-patched group. Asymptomatic greater than 50% diameter restenosis occurred in four and asymptomatic occlusion in one non-patched carotids. There were no restenosis, no occlusions and no neurologic symptoms in the patched group. Morbidity, mortality, restenosis or thrombosis-occlusion occurred in 10/100 (10%) non-patched and 0/100 (0%) patched arteries (p less than 0.01 by Chi Square). Restenosis or thrombosis-occlusion occurred in 9/100 (9%) of non-patched and 0/100 (0%) patched arteries (p less than 0.01). These results support the use of saphenous vein patch angioplasty reconstruction of carotid endarterectomy to protect against early restenosis and thrombosis-occlusion.

Computerised EEG monitoring for carotid endarterectomy

A prospective study was undertaken in twenty patients undergoing carotid endarterectomy using computerised EEG monitoring in the form of a density-modulated spectral array, spectral edge frequency and integrated EEG power for monitoring cerebral ischaemia. This form of monitoring proved to be easy to use and understand. Because ischaemic EEG events longer than one minute were not necessarily followed by postoperative deficits, the definition of significant events that would cause ischaemia may need to be modified.

ISI values and interhemispheric differences in patients with ischemic cerebrovascular disease; correlations with clinical and angiographic findings

Xenon 133 inhalation CBF studies of one hundred patients with ischemic cerebrovascular disease in the territory of the carotid artery were compared in an attempt to gain more insight into the collateral capacity, especially in those with a stenosis or occlusion of one of the major arteries. Asymmetry of the ISI values for the two hemispheres was expressed as a ratio. High ratios (greater ISI asymmetries) were found for patients with an occlusion of the internal carotid or middle cerebral artery, especially--but not exclusively--those with the more severe clinical symptoms. It also appeared that even when the patient is in a good clinical condition, an elevated ratio reflects insufficiency of the collateral supply to the affected side. The ISI values for individual patients seem to be less useful, partly due to the variable age dependency of this flow parameter.

Carotid endarterectomy. Review of 150 consecutive cases in two small community hospitals

The authors have reviewed 150 consecutive carotid endarterectomies in 140 patients performed by three neurosurgeons. These were performed in two small community hospitals. There was an overall mortality rate of 1.3%; major or minor stroke was seen in 2.7% of patients and transient neurological dysfunction in 2.7%. Preoperative symptoms included major or minor stroke in 39.3% of patients and transient neurological dysfunction in 43.3%; 17.3% of patients were asymptomatic. The patients were continuously monitored intraoperatively with electroencephalography. There were two operative deaths, both related to myocardial infarction and both on the 2nd postoperative day. These statistics appear to compare favorably with those of series reported by major institutions. The average number of carotid endarterectomies per surgeon per year was 10. These were performed over a 7-year period (October, 1976, through November, 1983). Previous series have implied the need for higher frequency in performing the procedure to assure low morbidity and mortality rates. This series appears to offer evidence to the contrary. A key to these results has been that in 148 of the 150 operations, the primary surgeon has been assisted by one of the other two neurosurgeons. This affords the primary surgeon the benefit of excellent technical assistance, and also broadens the experience of the assisting surgeon, thereby allowing maximum experience from the small volume of cases.

Combined carotid coronary reconstructions--synchronous or sequential?

Analysis of 16 synchronous with 26 sequential combined carotid coronary reconstructions showed no statistical advantage of either approach. Sequential operations are more convenient but increase the total operating time by an hour or so. Synchronous operations can be carried out without carotid shunting despite hypotension provided hypothermia is established. In other circumstances the internal carotid back pressure is used to indicate the need for carotid shunting. In the 42 patients there were three strokes (7%) including one fatal stroke (2%) and two myocardial infarctions, both fatal (5%).

Fluid filled oculoplethysmography and carotid artery disease: imperfect but useful

Fluid filled oculoplethysmography (OPG) is a widely used method of assessing carotid stenosis but it has limitations in the detection of bilateral internal carotid artery lesions and of external carotid artery stenoses. In this study, 157 consecutive patients having carotid angiography and fluid filled OPG were assessed to determine the accuracy of the technique and define the sources of error. Haemodynamically significant stenosis (HDS) was defined as at least 50% stenosis of the internal carotid artery (ICA). Only the most severely stenosed side of the 35 bilateral HDS lesions was detected owing to the poor reliability of ear pulse delays. Eye/eye delays alone detected the most severely stenosed side in 82 of 98 patients with an HDS stenosis of one or both ICAs for a sensitivity of 84% a specificity of 71% (41/59) and accuracy of 79% (81/157). The measurement of ear/ear pulse delays for external carotid artery (ECA) stenosis had a sensitivity of only 15% (5/34). Ear/eye pulse delays detected none of the 35 patients with bilateral HDS ICA stenosis. Bilateral equal HDS ICA stenoses were a significant source of error. Stenotic disease was present in the aortic arch and branches (five patients) or the carotid siphon (eight patients) and in seven cases it resulted in an incorrect localization on OPG. There was no diagnostic relationship between the severity of delay and the presence of total occlusion. Chronic local eye pathology was present in 13 patients and did not affect the results of the OPG. We have ceased to use ear pulse measurements for routine assessment but continue to use the eye/eye delays in conjunction with a carotid doppler imaging system.