Correlation of postoperative and two-year follow-up angiography with neurological function in 99 carotid endarterectomies in 86 consecutive patients

A systematic review of patch angioplasty versus primary closure for carotid endarterectomy

BACKGROUND

Guidelines recommend routine patching after carotid endarterectomy (CEA) on the basis of a lower restenosis rate and presumed lower procedural stroke rate than with primary repair. Underlying evidence is based on studies performed decades ago with perioperative care that significantly differed from current standards. Recent studies raise doubt about routine patching and have suggested that a more selective approach to patch closure (PAC) might be noninferior for procedural safety and long-term stroke prevention. The objective was to review the literature on the procedural safety and perioperative stroke prevention of PAC compared with primary closure (PRC) after CEA.

METHODS

MEDLINE, Embase, and Cochrane Central Register of Controlled Trials databases were searched from January 1966 to September 2017. Two authors independently performed the search, study selection, assessment of methodologic quality, and data extraction. Articles were eligible if they compared PAC and PRC after CEA, were published in English, included human studies, and had a full text available. Methodologic quality for nonrandomized studies was assessed using the Methodological Index for Non-Randomized Studies score; randomized controlled trials were assessed using Grading of Recommendations Assessment, Development, and Evaluation. Nonrandomized studies with a score ≤15 were excluded. The primary outcome measure was 30-day stroke risk. Secondary outcome measures were long-term restenosis (>50%) and postoperative bleeding.

RESULTS

Twenty-nine articles met the inclusion criteria, 9 randomized studies and 20 nonrandomized studies, for a total of 12,696 patients and 13,219 CEAs. Overall 30-day stroke risk was higher in the PRC group (odds ratio [OR], 1.9; 95% confidence interval [CI], 1.2-2.9). After exclusion of nonrandomized studies, this difference was not statistically significant anymore (OR, 1.8; 95% CI, 0.8-3.9). The restenosis rate was higher after PRC (OR, 2.2; 95% CI, 1.4-3.4). There were no differences in bleeding complications. Methodologic quality of the nonrandomized studies was moderate, and seven were excluded. Quality of the evidence according to Grading of Recommendations Assessment, Development, and Evaluation was moderate for restenosis, 30-day stroke, and bleeding.

CONCLUSIONS

In this systematic review, on the basis of moderate-quality evidence, perioperative stroke rate was lower after PAC compared with PRC. The rate of restenosis was higher after PRC, although the clinical significance of this finding in terms of long-term stroke prevention remained unclear.

Carotid surgery without external carotid endarterectomy: a 6-year clinical experience with 1027 cases

PURPOSE

previously we routinely performed endarterectomy of the external carotid artery (ECA) during carotid surgery. However, discouraging experience and lack of supportive data in the literature made us question its necessity. The present report describes our experience with a modified carotid endarterectomy (CEA) technique where the ECA is left undisturbed regardless of its degree of stenosis.

METHODS

from January 1996 to June 2001, 1027 CEAs were performed in 905 patients with this technique at our institution. All operations were performed for at least 60% internal carotid artery (ICA) stenosis. A preoperative carotid duplex scan was available for review in 990 cases (96%). Follow-up duplex scans were recovered from 0 to 1 months in 851 cases (83%) and from >1 month in 655 cases (64%). Seventy percent of these cases were performed for asymptomatic lesions.

RESULTS

the perioperative (30-day) mortality rate for the entire group of patients was 0.5% and the stroke rate was 0.7%. Mean follow-up was 18 months (range: 2-66 months). Only two ECAs occluded in the first postoperative month. During the follow-up period, 37 additional ECAs (5.6%) were found to progress from mild to severe (>75%) stenosis postoperatively. In addition, 7% of the cases were found to have worsened the degree of stenosis, 8% improved and 85% remained unchanged.

CONCLUSION

these data support sparing of the ECA during CEA.

The outcome of external carotid endarterectomy during routine carotid endarterectomy

PURPOSE

This study is an analysis of the outcome of a common method of management of the external carotid artery (ECA) during routine carotid endarterectomy (CEA).

METHODS

Between 1986 and 1997, 1069 primary CEAs were performed with a combination of proximal eversion technique and blind distal endarterectomy on the ECA. Of these, 973 CEAs (91%) had 1 or more postoperative duplex scans that included the ECA. Both preoperative and early postoperative studies were performed on 313 of these CEAs. Intraoperative post-CEA continuous-wave Doppler scans identified low flow or occlusion of the ECA in 37 CEAs (4%). These ECAs were isolated and repaired.

RESULTS

The early post-CEA duplex scan velocities were 143 +/- 81 cm/s (mean +/- 1 standard deviation of the mean). In the first 6 months after the CEAs, 692 ECAs (72%) had <50% stenosis, 175 (18%) had 50% to 74% stenosis, 90 (9%) had > or =75% stenosis, and 9 (1%) were occluded. Of the 37 repaired ECAs, 20 (54%) had <50% stenosis, 10 (27%) had 50% to 74% stenosis, 5 (14%) had > or =75% stenosis, and 2 (5%) were occluded. The cumulative life-table > or =50% stenosis rate was 36% at 1 year, 40% at 3 years, 48% at 5 years, and 81% at 10 years. The cumulative > or =75% stenosis rate was 12% at 1 year, 12% at 3 years, 15% at 5 years, and 37% at 10 years. Preoperative studies showed <50% stenosis in 152 of the 313 ECAs (48%). In the early postoperative period, 102 of these ECAs (66%) had <50% stenosis, 35 (23%) had 50% to 74% stenosis, 13 (9%) had > or =75% stenosis, and 3 (2%) were occluded. Of the 161 ECAs with > or =50% preoperative stenosis, 66 (41%) had <50% stenosis in the first 6 months after CEA, 61 (38%) had 50% to 74% stenosis, 32 (20%) had > or =75% stenosis, and 2 (1%) were occluded.

CONCLUSIONS

Combined proximal eversion technique and blind distal ECA endarterectomy during routine CEA gives poor and unacceptable early and late outcomes. The repair of severely obstructed or occluded ECA identified during surgery after CEA has a similarly poor outcome. The technique and management of the ECA during routine CEA needs further investigation and modification.

Carotid endarterectomy with homologous vein patch angioplasty: a review of 1006 cases

PURPOSE

Because homologous vein is rarely used in vascular reconstructions, we evaluated the homologous vein as a patch for the reconstruction of the carotid bifurcation after endarterectomy.

METHODS

Excess vein harvested during open heart operations was either refrigerated in saline solution or cryopreserved in a solution of 10% dimethyl sulfoxide. Donors were tested for transmissible infections, and the veins were cultured for common pathogens. Data were analyzed from 837 consecutive patients (1006 cases) who underwent carotid endarterectomy with homologous vein patch angioplasty between 1981 and 1993.

RESULTS

The perioperative mortality rate was 0.8% (eight patients). Two deaths (0.2%) were attributed to ipsilateral strokes. Ischemic strokes occurred in 12 patients (1.2%; 10 ipsilateral), and ipsilateral transient ischemic attacks occurred in three patients (0.3%). Follow-up data were obtained for 482 patients (56%; mean follow-up time, 61 months; range, 1 to 132 months). Ipsilateral recurrent symptoms occurred in eight patients (1.7%; seven strokes, one transient ischemic attack). Of the 63 late deaths (13%), the majority (25 patients; 40%) were caused by complications of coronary artery disease. The 10-year overall survival rate was 76% +/- 3.2%, and the 10-year rate of freedom from late ipsilateral morbidity was 96% +/- 1.4%. The 10-year rate of freedom from late stenosis (a reduction in diameter of > or = 20%) in the 220 arteries (22%) that were studied by duplex scan was 84% +/- 2.3%.

CONCLUSIONS

The postoperative mortality and neurologic morbidity rates of carotid endarterectomy with homologous vein patch angioplasty are similar to those in the best series with all types of closure. The existing long-term follow-up data indicate that the homologous vein is a durable patch that behaves like other patches used in the same location.

The natural history of the external carotid artery after carotid endarterectomy: implications for management

PURPOSE

Most surgeons perform some type of endarterectomy of the external carotid artery (ECA) routinely during standard carotid endarterectomy (CEA). This approach has been shown to result in a small percentage of ECA occlusions, the clinical significance of which remains poorly understood. We have modified our approach to the management of the ECA during standard CEA by averting any attempt at external CEA. To evaluate the natural history of the untreated ECA after CEA, we reviewed the preoperative, postoperative, and follow-up duplex scans obtained from 232 CEAs over the past 4 years.

METHODS

Preoperative and postoperative carotid artery duplex examinations with specific evaluation of the extent of ECA stenosis were available for review on 114 CEAs performed between January 1991 and July 1994. All CEAs were performed for internal carotid artery stenosis greater than 75% as determined by duplex scanning, which was confirmed by either contrast arteriography or magnetic resonance angiography.

RESULTS

Seventy-three (64.0%) procedures were performed for symptomatic lesions, whereas 41 (36.0%) were performed for asymptomatic stenosis. There were no perioperative strokes or transient ischemic attacks in this group, and there was one postoperative death (0.9%). Short- and intermediate-term follow-up demonstrated insignificant changes in ECA diameter after operation, with no cases of ECA occlusion and only five cases progressing to greater than 75% on the 1-year follow up duplex examination.

CONCLUSION

We conclude from these data that averting external CEA during standard CEA does not result in significant progression of ECA stenosis or occlusion.

Eversion endarterectomy of the internal carotid artery: midterm results of a new technique

A new eversion endarterectomy technique was used in 65 internal carotid artery reconstructions in 56 patients. The original features of the technique include a complete oblique transection of the internal carotid artery distal to the lesion and eversion endarterectomy through a longitudinal incision of the common carotid and external carotid arteries. The mean age of the patients was 68.2 +/- 7.8 years. Seventy-three percent of the patients had hypertension and 45.5% had coronary heart disease. Fifty-four percent experienced neurologic symptoms (transient in 36%, reversible in 6%, and permanent in 11%). Operations were performed under general anesthesia. An indwelling shunt was inserted whenever routine stump pressure was < 50 mmHg. There were no neurologic complications but one patient died of a compression hematoma of the neck, for a combined mortality and morbidity rate of 1.5%. Arteriograms were obtained from all patients on day 5 and showed complete restoration of normal anatomy in all cases and thrombosis of the external carotid artery in one. During a mean follow-up of 27 +/- 4.7 months no strokes were observed. Follow-up duplex scans showed no hemodynamically significant restenoses. Eversion endarterectomy is a reliable alternative to other reconstruction procedures of the internal carotid artery.

Safety and durability of redo carotid endarterectomy for recurrent carotid artery stenosis

We retrospectively reviewed the records of patients who underwent redo carotid endarterectomies during a 5-year period. Patients were followed by duplex ultrasound to assess late patency of the carotid artery. Reoperations for recurrent carotid stenosis were performed in 46 of 973 patients who had carotid endarterectomies (5%). Indications for surgery were hemispheric transient ischemic attacks (TIA) in 33 (72%) and asymptomatic greater than 80% stenosis in 13 (28%). Pathologic findings revealed that the cause of recurrence was myointimal hyperplasia in 11 patients (24%), with a mean recurrence interval of 12.8 postoperative months, and atherosclerosis in 35 (76%), with a mean recurrence interval of 84 postoperative months (P = 0.0002). Redo endarterectomy with patch angioplasty was used for reconstruction in 32 cases (70%), patch angioplasty alone in 11 (24%), and endarterectomy with primary closure in 3. There were 3 perioperative strokes (7%). Late follow-up (mean 30.9 months) revealed no strokes and 1 TIA. Of 40 patients, 34 (85%) were alive and stroke free. Although six late deaths occurred, none were stroke related. One patient (2%) had late significant second recurrent carotid stenosis. Redo carotid endarterectomy for symptomatic patients and asymptomatic high-grade stenosis is safe and durable.

Intraoperative duplex monitoring of the carotid bifurcation for the detection of technical defects

OBJECTIVES

Intraoperative Duplex examination can be used to identify technical imperfections during carotid endarterectomy. The objectives of this study were: (1) to evaluate the technical feasibility of intraoperative Duplex; (2) to compare Duplex findings with contrast arteriography; (3) to correlate intraoperative Duplex findings with postoperative complications and with Duplex data obtained during follow-up.

DESIGN

Prospective clinical study.

SETTING

Department of Vascular Surgery, Catharina Hospital, Eindhoven, The Netherlands.

MATERIALS

44 patients underwent Duplex scanning at the completion of carotid endarterectomy. In addition intraoperative arteriography was performed in the first 16 consecutive patients. Follow-up included a Duplex examination at three monthly intervals during the first postoperative year.

OUTCOME MEASURES

Technical defects and flow disturbance at the time of surgery, and postoperative restenosis.

RESULTS

At contrast arteriography a distal intimal ridge with 15-20% diameter reduction was observed in two, an occlusion of the external carotid artery in three and moderate kinking in one patient. All abnormalities were identified at Duplex imaging. In none of the cases were the Duplex findings considered an indication to re-explore the endarterectomised internal carotid artery. Postoperative complications occurred in six patients: three strokes, two transient ischaemic attacks and two internal carotid occlusions (in one patient combined with a stroke). Severe spectral broadening (spectral class D) correlated significantly with early postoperative complications (p = 0.027). In contrast, moderate defects on Duplex imaging did not correlate significantly with early complications. Duplex examination during the first year of follow-up demonstrated recurrent stenosis in four patients. Intraoperative spectral broadening did not correlate significantly with the development of common or internal carotid restenosis. However, external carotid recurrent stenosis was positively related to intraoperative flow disturbance (p = 0.0003).

CONCLUSION

Duplex scanning is easy to use after completion of carotid endarterectomy. There is good agreement between intraoperative Duplex scanning and contrast arteriography. Extensive spectral broadening of the Doppler velocity signal is associated with an increased prevalence of early postoperative complications. Restenosis at follow-up appears to be related to severe flow disturbance as was demonstrated for the external carotid artery.

Surgical decisions on the basis of magnetic resonance angiography of the carotid arteries

The recent demonstration of the efficacy of carotid endarterectomy in certain patients emphasizes the advantages of having a noninvasive, accurate means of evaluating the carotid arteries. Advances in magnetic resonance (MR) angiography now allow accurate depiction of the carotid arteries that may be adequate for surgical planning in many cases. This report examines the accuracy of MR angiography compared with that of conventional angiography in symptomatic patients undergoing carotid endarterectomy and compares them with surgical findings. Twenty-one carotid arteries in 20 patients were treated surgically for severe stenosis or occlusion. Preoperatively, all patients had both MR and conventional angiograms, which were interpreted on a five-grade scale by two independent neuroradiologists who were unaware of the patient's clinical history. The two studies were highly correlated, particularly in the case of severe stenosis and occlusion. There were no false-negative MR studies that missed surgically significant lesions. In two cases, MR angiography overestimated the stenosis by one grade. On MR angiography, surgically significant stenosis appears as focal areas of signal intensity loss at the level of stenosis with reappearance of the signal distally. If the distal signal intensity does not reappear, the artery is likely to be occluded. In symptomatic patients, MR angiograms that demonstrate a flow-void gap with distal reappearance at a site consistent with the symptoms may be adequate as the sole preoperative study. Three patients who underwent carotid endarterectomy on this basis are presented. The factors that contribute to artifactual and overestimated stenosis are reviewed.

Carotid endarterectomy complicated by vein patch rupture

Saphenous vein patch angioplasty has been used to improve the results of carotid endarterectomy by decreasing the incidence of postoperative occlusion and recurrent stenosis. A rare but potentially lethal complication of this technique is aseptic necrosis and rupture of the vein patch during the postoperative period. We report three cases of this phenomenon and review an additional 13 cases from the literature. This event generally occurs without warning 2 to 7 days postoperatively and may result in death or stroke. At reoperation, the central portion of the vein patch is necrotic, without evidence of infection. Technical considerations in the harvesting and preparation of these grafts are reviewed, as are the physical parameters predisposing certain vein patches to rupture. Saphenous vein harvested from the ankle has been linked to every reported case. Small diameter veins in particular appear to carry a higher risk of rupture.

Deriving clinical prediction rules from stroke outcome research

BACKGROUND AND PURPOSE

Our purpose was to determine whether clinical prediction rules could be derived from current stroke outcome research.

SUMMARY OF REPORT

We reviewed 92 articles on stroke outcome research to determine their suitability for implementation as a clinical prediction rule. Methodological problems in many of these studies made implementation of their results as a clinical prediction rule difficult.

CONCLUSIONS

Implementation of stroke outcome research as clinical prediction rules would be facilitated by description of patient population demographics; precise definitions of predictor and outcome measures; stratification of patients by stroke mechanism; use of adequate patient sample sizes; and description of the mathematical methods used, including coding schemes, cutpoints, beta coefficients, constant terms, and a priori probabilities.

Late follow-up of carotid endarterectomy with venous patch angioplasty

Ninety carotid endarterectomies with venous patch angioplasty were performed in 83 patients between July 1980 and December 1985. The primary indication for patching was a small-caliber internal carotid artery (ICA) with a diameter less than 3.0 mm in 54 arteriotomies (60%). Patency of the endarterectomy was evaluated by completion arteriography in all instances. Follow-up was conducted after an intermediate postoperative period of 21 +/- 12.5 months in 69 sides by arteriography. A late follow-up was conducted at 55.4 +/- 11.2 months either by arteriography (in 45 sides) or by carotid duplex scanning (in 11 sides). Twenty-one patients with 23 endarterectomies died, only 1 of a cerebral event. Seven patients moved or refused study and five were lost to follow-up. Three recurrent stenoses and five carotid occlusions developed by the time of the intermediate follow-up. By the time of late follow-up, three additional patients developed recurrent stenoses. Our results suggest that recurrent stenosis continues to develop with a longer period of follow-up in patients undergoing venous patch angioplasty with carotid endarterectomy.

Does carotid restenosis predict an increased risk of late symptoms, stroke, or death?

The identification of carotid restenosis as an unexpected late complication of carotid endarterectomy has prompted concerns regarding its importance as a source of new cerebral symptoms, stroke, and death. To investigate these concerns, we analyzed a consecutive series of 507 patients undergoing 566 carotid endarterectomies, each documented as technically satisfactory. Post-operative duplex Doppler examination data at 3 days, 1, 3, 6, 12 months, and annually thereafter in 484 arteries (85.5%) permitted classification of these arteries according to the most severe degree of postoperative stenosis: normal (n = 306); 1% to 19% (n = 89); 20% to 50% (n = 40); more than 50% (n = 49, including 8 occluded). The incidence of more than 50% restenosis was 14.5% in female and 7.7% in male patients (p = 0.003). Life table analyses to 10 years revealed a significantly greater life expectancy among those with restenosis (p = 0.05). Stroke was also less likely in patients with restenosis, although this difference did not reach statistical significance. When survival and stroke were both endpoints, the likelihood of patients with more than 50% restenosis remaining alive and stroke free was also greater than the less than 20% stenotic group (p = 0.03). Thus patients with carotid restenosis were less likely than patients with normal postoperative scans to have late symptoms, stroke, or early death.

Prospective study of the effectiveness and durability of carotid endarterectomy

In a series of 252 consecutive patients who underwent 282 carotid endarterectomies, we conducted clinical and angiographic follow-up for 2 to 6 years (mean, 3.2 years). Digital subtraction angiography (DSA) was done postoperatively in 95% of cases. Clinical follow-up was achieved in 97% of cases, and DSA follow-up was obtained in 66% of cases. The overall group had a 1% operative minor morbidity (three cases of minimal new neurologic deficit), no major morbidity, and a 0.7% mortality (one death from stroke and one from myocardial infarction). Complications correlated well with the patient's preoperative risk category. During follow-up, 10 minor strokes, only 1 of which was attributable to the reconstructed artery, and 10 transient ischemic attacks, 3 of which were presumably related to recurrent stenosis, occurred. Asymptomatic mild to moderate restenosis of the internal carotid or common carotid artery was identified in 10% of follow-up DSAs and severe stenosis or occlusion in 3%. Stenosis in the opposite common carotid or internal carotid artery progressed in 48 cases (26% of follow-up DSAs and ultrasound studies), and 10 of these became symptomatic. An actuarial analysis of patients who had endarterectomy indicated that the cumulative probability of ipsilateral stroke was 1.5% at 1 month and 2% at 5 years. The cumulative probability of ipsilateral stroke, transient ischemic attack, or reversible ischemic neurologic deficit was 4% at 1 month and 8% at 5 years or less than 1% per year after the first month, with censoring at the time of the second surgical procedure.

Combined carotid endarterectomy and myocardial revascularization

From February 1971 through December 1987, 95 patients underwent combined carotid endarterectomy and myocardial revascularization. Mortality and postoperative stroke rates were 4 percent and 2 percent, respectively, for the 16-year experience. From 1980 to 1987, when 89 percent of patients had their operation, mortality and stroke rates were 1 percent and 2 percent, respectively. Follow-up carotid duplex scan in 41 patients revealed that 25 percent had more than 50 percent restenosis. Only two in this group were symptomatic. We conclude that the combined approach to concomitant carotid and coronary artery atherosclerosis can be done safely. Continued study with noninvasive testing is important to document restenosis rates.

Effectiveness of carotid endarterectomy for asymptomatic carotid stenosis: design of a clinical trial. Mayo Asymptomatic Carotid Endarterectomy Study Group

A clinical trial, as described in this report, has been designed to compare the effects of carotid endarterectomy and medical treatment with aspirin for prevention of transient ischemic attack, reversible ischemic neurologic deficit, and ischemic stroke in patients with asymptomatic pressure-significant carotid stenosis. A prospective randomized controlled trial design is being used, and selection of patients with asymptomatic pressure-significant carotid stenosis is based on the results of ocular pneumoplethysmography and either duplex ultrasound scanning or digital subtraction angiography. Patients are randomized to either surgical (carotid endarterectomy) or medical (aspirin, 80 mg/day) treatment, and follow-up assessment is accomplished by return visits and patient questionnaires. A total of 945 patient-years of follow-up will accumulated for each of the medical and surgical groups.

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.

Surgery for radiation-induced symptomatic carotid atherosclerosis

Carotid atherosclerosis occurring secondary to cervical irradiation is known to produce stroke. Transient neurologic symptoms have necessitated surgical intervention to prevent stroke despite concern over technical problems, wound healing, operative risks, and uncertain therapeutic outcome. With this report, 26 surgical procedures in 20 patients are now documented in the literature (12 men--60%; eight women--40%). Mean age of these patients (56 years) was 10 years younger than carotid surgery patients with no prior radiation history. No relationship was noted between elevated serum cholesterol and the subsequent development of radiation-induced carotid atherosclerosis. Surgical procedures performed included carotid endarterectomy in 17 cases (65%) and arterial bypass in nine (35%). The combination of radiation therapy and previous neck surgery, including prior radical neck dissection, did not adversely influence operability. Surgical outcome was uniformly good with only one stroke (4%) documented in the perioperative period. Longer follow-up on our six cases (mean two years) disclosed neither new clinical symptoms nor the development of hemodynamically significant restenosis.

Carotid endarterectomy: to shunt or not to shunt

Because of controversies in the cerebrovascular literature regarding the use of an intraluminal shunt in carotid endarterectomy, we report a randomized prospective study of 118 consecutive symptomatic patients receiving surgery within a single neurosurgical practice. Over 4 years, 138 carotid endarterectomies were performed in the 118 patients, 63 operations with intraluminal shunting and 75 without. Standard rationale for surgery included ipsilateral cerebral infarction in 38% of the operations and ipsilateral transient ischemic attacks in 36%. Unilateral angiographic stenosis of greater than 90% was seen in 58% of the operations; there were no ipsilateral occlusions. Surgery was performed under general anesthesia with barbiturate induction and mild blood pressure elevation. The 30-day complication rate included a mortality rate of 0.7% with a 5.1% incidence of postoperative neurologic deficit and a 1.4% rate of myocardial infarction. In the 24 hours after surgery there were no cerebral infarctions in the shunted group and six in the unshunted group. This 8% rate in the unshunted group compared with 0% in the shunted group was significant at p = 0.023 with a power of 0.95 by Fisher's exact test and chi 2 analysis. This suggests that in our neurosurgical practice (resident training program) the use of an intraluminal shunt during carotid endarterectomy significantly reduces the risk of intraoperative neurologic deficit without increasing the incidence of other complications.

Hemodynamic significance of internal carotid artery disease

Neurologic symptoms in the region of an internal carotid artery stenosis are considered to be embolic in most instances. Only in a subgroup has carotid occlusive disease with impairment of the collateral supply, caused a state of hemodynamic failure with marked reduction of perfusion pressure. Though unproven, it is reasonable to assume that without surgical intervention, the risk is higher than average for patients with hemodynamic failure. Equally, should there be any postoperative improvement of cerebral blood flow or neurologic deficits, it should be looked for in this group. Thus, it is necessary to distinguish those with low perfusion pressure from the population of patients with carotid artery disease. Preoperative clinical evaluation and direct visualization of the carotid bifurcation should be supplemented by indirect physiological tests which allow assessment of collateral perfusion. Examination of periorbital flow direction or oculoplethysmography could be used as a screening procedure. Negative tests most certainly rule out any severe pressure gradient across the stenosis, irrespective of the luminal reduction. A positive result, on the other hand, should be further quantified since most indirect tests become positive at relatively small pressure gradients. Studies of cerebral blood flow at rest and during cerebral vasodilation makes it possible to identify patients with severe reduction of cerebral perfusion pressure. Such hemodynamic failure of one hemisphere may be identified in most cases by a conventional non-invasive xenon-133 technique and stationary detectors. Smaller focal regions of hypoperfusion may be identified by computer emission tomography, either by the detection of single-photon emission or by paired detection of annihilation photons. Endarterectomy does improve cerebral hemodynamics in terms of increased flow through the reconstructed vessel and elimination of pressure gradients. The cerebral blood flow, though remains unchanged in the majority of patients, at least when measured at baseline. Only in those patients with a reduction in perfusion pressure can a significant improvement in baseline flow occur. Flow reserve determined by cerebral vasodilation, however, will improve in most patients with hemodynamic failure. In addition, some patients in the low-pressure group develop marked, but temporary, hyperperfusion after reconstruction of very high grade carotid stenosis. This is considered a result of chronic low perfusion pressure with subsequent loss of autoregulation, and autoregulatory control is first regained after some days.(ABSTRACT TRUNCATED AT 400 WORDS)

The geometry and mechanics of saphenous vein patch angioplasty after carotid endarterectomy

To elucidate some of the mechanisms that may account for the potential advantages and disadvantages of saphenous vein patch angioplasty (VPA) after endarterectomy of the carotid artery, the author evaluated 50 VPAs with respect to geometry, blood-flow velocities, and wall mechanics. The mean internal carotid artery (ICA) diameter cephalad to the vein patch was 4.5 mm, whereas the mean diameter of the patched segment was 7.4 mm. The mean ratio between the cross-sectional area of the patched ICA and the cross-sectional area calculated as if the artery were nonpatched was 2.9. In the presence of restenosis sufficient to occlude the nonpatched artery, this ratio was decreased to 1.9 when the artery alone was stenosed and to 0.49 when both the artery and the vein patch were stenosed. The mean ratio between the peak blood-flow velocity distal to the patch and the blood-flow velocity in the patched segment was 3.4. These area and velocity ratios indicate that the wall shear stress in the patched segment was three to five times lower than that in the distal ICA. The normal stress in the circumferential vein patch wall was two to three times greater than that in veins used as bypass grafts at the same intraluminal pressure. In comparison to primary arteriotomy closure after carotid endarterectomy, VPA provides a partially endothelialized flow surface, a significantly greater cross-sectional area, and a relatively mild wall shear stress; all three of these factors may protect the artery against both hemodynamically significant restenosis and early post-operative thrombosis.

A prospective study of vein patch angioplasty during carotid endarterectomy. Three-year results for 801 patients and 917 operations

From 1983 through 1985, 801 consecutive patients (mean age: 66 years) underwent 917 primary carotid endarterectomies at the Cleveland Clinic. Conventional arteriotomy closure was performed during 483 operations, while patch angioplasty using a distal segment of saphenous vein was employed in 434. Preoperative risk factors, surgical management, and antiplatelet therapy were equivalent in the vein patch (VP) and nonpatch (NP) groups. Early results were evaluated by intravenous angiography (DSA) in 715 patients (89%), and 332 reconstructions (36%) have been reassessed by objective imaging during a mean follow-up interval of 21 months. Ischemic strokes occurred after 18 (1.9%) of the 917 procedures (0.7% VP, 3.1% NP; p = 0.0084), and symptomatic (N = 9) or unsuspected (N = 8) thrombosis of the internal carotid artery was confirmed by neck exploration or routine DSA after 1.9% of all operations (0.5% VP, 3.1% NP; p = 0.0027). Only ten patients (1.2%) have required reoperations for severe recurrent lesions, but the cumulative 3-year incidence of new defects (greater than or equal to 30% stenosis) documented by objective studies in the VP and NP groups was 9% and 31%, respectively (p = 0.0066). These results strongly suggest that VP angioplasty enhances the safety and durability of carotid endarterectomy.

Recurrent carotid stenosis. Results and complications of 57 operations

Among 1992 patients undergoing carotid endarterectomy from January 1972 through December 1984, 57 operations were performed in 51 patients for recurrent carotid stenosis. Thirty-four of these cases had undergone initial surgery at this institution while 23 had endarterectomy elsewhere. Fifty-two of the 57 operations were for symptomatic disease while five were for evidence of a progressing lesion. All operative procedures were monitored with intracerebral blood flow measurements and continuous electroencephalograms. Twenty-three patients required intraoperative shunting. There were no complications related to shunt usage or to the period of temporary occlusion in patients who did not require shunting. Recurrent stenosis was related to intimal hyperplasia in 14 cases, recurrent atherosclerosis with interluminal thrombi or degenerated plaque in 27, unexplained soft thrombus in eight, proximal scarring in six, and to aneurysms in two. Intimal hyperplasia was the most common cause for restenosis within 2 years from the date of surgery and developed earlier in patients with a primary closure than in patients closed with a patch graft. The operative complication rate was 10.5% or 4 times the risk of surgery for primary atherosclerosis at this institution. Complications were attributed primarily to intraoperative and postoperative thromboembolic events related to apparent increased thrombogenicity of these vessels. The highest complication rate occurred in the group of patients undergoing surgery for thrombotic material in the internal carotid artery, either primary or with underlying atherosclerosis. There were no neurological complications in the group with myointimal hyperplasia. The authors' experience suggests that on-lay patch grafting without endarterectomy should be used in patients with myointimal hyperplasia. Patients with complicated recurrent atherosclerosis can be treated with endarterectomy and patch grafting, but interposition vein grafts should be considered in cases in which the vessels are extensively damaged by the recurrent plaque or with an unexplained thrombus at the site of previous endarterectomy.