Carotid endarterectomy

Fate of the external carotid artery following carotid interventions

OBJECTIVE

The external carotid artery (ECA) is an important collateral pathway for cerebral blood flow. Carotid artery stenting (CAS) typically crosses the ECA, while carotid endarterectomy (CEA) includes deliberate ECA plaque removal. The purpose of the present study was to compare the long-term patency of the ECA following CAS and CEA as determined by carotid duplex ultrasound.

METHODS

Duplex ultrasounds and hospital records were reviewed for consecutive patients undergoing CAS between February 2002 and April 2008, and were compared with those undergoing CEA in the same time period. Preoperative and postoperative ECA peak systolic velocities were normalized to the common carotid artery (CCA) as ECA/CCA ratios. A significant (80% or greater) ECA stenosis was defined as an ECA/CCA ratio of 4.0. A change of ratio by more than 1 was defined as significant. Data were analyzed using Student's t test and χ(2) analysis.

RESULTS

A total of 86 CAS procedures in 83 patients were performed (81 men, mean age 69.9 years). Among them, 38.4% of patients had previous CEA, 9.6% of whom had contralateral internal carotid artery occlusion. Sixty-seven CAS and 65 CEA patients with complete duplex data in the same time period were included in the analyses. There was no difference in the incidence of severe ECA stenosis on preoperative ultrasound evaluations. During a mean follow-up of 34 months (range four to 78 months), three postprocedure ECA occlusions were found in the CAS group. The likelihood of severe stenosis or occlusion following CAS was 28.3%, compared with 11% following CEA (P<0.025). However, 62% of CEA patients and 57% of CAS patients had no significant change in ECA status. Reduction in the patient's degree of ECA stenosis was observed in 9.4% of CAS versus 26.6% of CEA patients. Overall, immediate postoperative ratios of both groups were slightly improved, but there was a trend of more disease progression in the CAS group during follow-up.

CONCLUSION

CAS is associated with a higher incidence of post-procedure ECA stenosis. Despite the absence of neurological symptoms, a trend toward late disease progression of ECA following CAS warrants long-term evaluation.

Carotid endarterectomy in adults 50 years of age and younger: a retrospective comparative study

PURPOSE

Atherosclerotic carotid artery stenosis (CAS) is the most common cause of stroke in young adults. We retrospectively studied clinical characteristics of premature CAS and the safety and durability of carotid endarterectomy (CEA) in 56 patients 50 years of age or younger (mean, 46.4 years; 34 (60%) males; group I) who underwent primary CEA at the Cleveland Clinic between 1983 and 1993.

METHODS

The patients were identified from the Vascular Surgery Registry and were compared with 202 randomly selected patients 60 years of age and older (mean, 69.3 years; group II) who were frequency-matched by gender and the year of primary CEA. Carotid shunting was used routinely, and the arteriotomy was patched in the majority of cases. Patients were followed-up for mean of 47.2 months (group I) and 46.0 months (group II).

RESULTS

No significant differences were found in the indications for CEA (symptomatic CAS, 49% in group I vs 48% in group II) or the prevalence of diabetes, coronary diseases, and lower extremity arterial disease. Younger adults were more likely to have a history of smoking (93% vs 76%; p = 0.005), hypertension (71% vs 52%; p = 0.006), premature menopause (57% vs 18%; p < 0.001) and had lower levels of high-density lipoprotein cholesterol (p = 0.03). There were no in-hospital deaths. Perioperative strokes in the distribution of the operated artery occurred within 24 hours in one younger patient (1.8%) and in one older patient (0.5%). This was attributed to early carotid thrombosis in the young patient. Major late postoperative neurologic complications were documented in one young patient (1.8%) and six older patients (3%). Patients in group I were at significantly higher risk for recurrent carotid stenosis (risk ratio, 3.1; 95% confidence interval [CI], 1.3 to 7.3; p = 0.010); younger individuals remained at significantly higher risk for recurrent stenosis even after adjusting for smoking and hypertension (risk ratio, 3.7; 95% CI, 1.5 to 9.4; p = 0.006). By life-table analysis, younger adults tended to have a higher rate of late reoperations (p = 0.065).

CONCLUSIONS

CEA can be safely performed in young adults with premature CAS, although younger individuals appear to have higher rates of recurrent carotid stenosis compared with older counterparts.

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.

Monitoring of somatosensory evoked potentials during carotid endarterectomy

Somatosensory evoked potentials (SEPs) were monitored in the course of 368 carotid endarterectomies (CEAs) carried out in 312 patients. In an initial group of 26 patients the shunt was used routinely while in a second group, involving 342 CEAs, it was applied selectively on the basis of modifications which the SEP underwent during clamping. The criterion for shunting was the progressive reduction, up to 50%, of the N20-P25 amplitude. New postoperative neurological deficits appeared in 6 patients, all of whom displayed a transitory SEP flattening. The SEPs of 2 of these returned to normal by the time they awoke and both showed a clinical deficit homolateral to the operated side. In only 2 cases did the deficit fail to regress completely and their postoperative CT scans revealed ischaemic lesions. A positive relationship emerged between SEP changes and back pressure values; nonetheless, as many as 75% of the patients with low residual back pressure values (less than 25 mmHg) tolerated the clamping. SEP monitoring appears to provide a reliable basis for selectively applying a shunt when there is a high risk of haemodynamic ischaemia during clamping.

An assessment of the variability of early scalp-components of the somatosensory evoked response in uncomplicated, unshunted carotid endarterectomy

Although many publications deal with the usefulness of the SER in CEAs, the criteria of calling a SER abnormal during a CEA are largely arbitrary. One way to define the limits of normalcy for SERs during the CEA will be to analyze the SER tracings obtained during unshunted and uncomplicated (intra- and postoperative) CEAs. In 23 such CEAs (10 right, 13 left; clamptime 10-23 mins.), data analysis at the ipsilateral parietal electrode, on stimulation of the contralateral median nerve (square pulse -5.1/sec, 10-30 V, 200 microseconds; bandpass-30-3000 Hz trials-500 stimuli), revealed that (1) latency fluctuations of the N20 (21.4 msec) were narrowest, being less than 1.5 msec different during and after clamping compared to the preclamp latency in all 23 CEAs, whereas those of P25 (27.4 msec) and N35 (38.5 msec) were greater than 2.0 msec different from the preclamp latency in 3 and 8 CEAs respectively, and (2) the amplitudes of N20, P25 and N35 measured from the preceding peak of opposite polarity, fell to less than 75% of the preclamp value on 3, 4 and 7 CEAs respectively. It is concluded that N20 was the most stable of the first three short-latency components in the SER and should perhaps be most relied upon to predict abnormality of the SER during CEAs.

Saphenous vein patch grafts in carotid endarterectomy

The clinical data and findings on the early postoperative intravenous digital subtraction angiograms (IVDSA's) were studied in 61 patients undergoing 70 consecutive conventional carotid endarterectomies and in 46 patients undergoing 50 consecutive carotid endarterectomies with a saphenous vein patch graft (SVPG). The IVDSA's were considered normal in 50 of 70 conventional carotid endarterectomies and in 46 of 50 carotid endarterectomies with SVPG (p = 0.004). The internal carotid artery (ICA) origin was consistently larger and had a more normal configuration after carotid endarterectomy with SVPG. Ballooning at the endarterectomy site was an uncommon finding and occurred with similar frequency in both groups; that is, after three conventional carotid endarterectomies and two carotid endarterectomies with SVPG. In the conventional group, early symptomatic thrombosis occurred in the ICA in one patient and in the common carotid artery (CCA), ICA, and external carotid artery (ECA) in two patients. Silent ICA occlusion was seen in three patients in the conventional group. There were no occlusions in the SVPG group (p = 0.04). Stenosis at the distal end of the ICA arteriotomy was found after nine conventional carotid endarterectomies, and was mild (less than or equal to 33% reduction in the lumen) in seven patients, moderate (34% to 66%) in one, and severe (greater than or equal to 67%) in one. Mild distal ICA stenosis was seen in one case after carotid endarterectomy with a SVPG (p = 0.03). Stenosis of 33% or less was found at the proximal end of the CCA arteriotomy after two carotid endarterectomies in the conventional group and one carotid endarterectomy in the SVPG group. Four patients in the conventional group suffered a postoperative cerebral infarct and one patient in the SVPG group suffered a postoperative brain-stem infarct (p = 0.28). The authors' findings have led them to routinely use a SVPG in carotid endarterectomy.

Carotid endarterectomy in a small community hospital

Over a 10 year period carotid endarterectomy was performed in a total of 177 operations in 145 patients at a small community hospital. Mortality and morbidity rates were similar to those reported from larger medical centers. The use and comparison of intracerebral protective techniques of hypercarbia and shunting are discussed. Routine use of the Silastic shunt appears preferable to more elaborate means of cerebral protection. The noninvasive Dopscan and periorbital Doppler examination are effective tools in the selection of patients for surgery and follow-up of patients with asymptomatic bruits, contralateral stenoses or both. These noninvasive studies often add valuable information when the angiographic findings are uncertain. The treatment of asymptomatic carotid lesions remains controversial. Significant carotid stenosis or ulcerated plaque can be treated prophylactically by endarterectomy if the operator can show no hospital mortality and a reversible neurologic deficit of about 2 percent in his series.

Carotid endarterectomy

Thousands of carotid endarterectomies are now performed each year. In properly selected patients in the hands of competent surgeons, the mortality and morbidity rate should not exceed 2 per cent. Although the long-term results are good, this procedure is prophylactic, and a patient who has already sustained a fixed neurologic deficit will rarely be improved by increasing the blood flow in the carotid arteries. This procedure, probably more than any other in the armamentarium of the vascular surgeon, depends on meticulous attention to detail and careful and gentle handling of tissue.