Early control of distal internal carotid artery during carotid endarterectomy: does it reduce cerebral microemboli?

According to the results of the large trials on carotid endarterectomy (CEA), this type of surgery is only warranted if perioperative mortality and morbidity are kept considerably low. Less attention has been paid to methods of cerebral protection during CEA, although intraoperative transcranial Doppler (TCD) can visualise intracerebral microemboli (MES) during routine carotid dissection, although MES occur throughout the CEA, only those during dissection are related to neurological outcome. Prevention of MES by means of early control of the distal internal carotid artery dislodging from the carotid artery plaque during dissection is very likely the mechanism behind an eventual benefit from this approach. Hence, the amount of MES might serve as a surrogate parameter for the risk of periprocedural neurological events. So, the aim of the present study was to evaluate whether early control of the distal carotid artery during CEA is capable of reducing the number of MES by means of a prospective randomised trial.

Twenty-eight patients (29 procedures) could be prospectively included in our study. Before surgery we randomly assigned the patients to two groups: group A (N.=12): CEA by means of early control of the distal internal carotid artery; group B (N.=17): CEA with dissection of the total carotid bifurcation before clamping the arteries. Periprocedurally, we continuously monitored the cerebral blood flow in the ipsilateral middle cerebral artery by means of TCD. Pre- and postoperative morbidity were independently verified by a neurologist <2 days before and not later than five days after the procedure. Values of microembolic signs during dissection were summarised with arithmetic means and standard deviations. For further analysis non parametric Wilcoxon test was performed between both methods. P-values <0.05 were considered as statistically significant. Wilcoxon test was performed to compare both methods concerning clamp- and procedure times.

We performed EEA 26 times, in three patients a longitudinal arteriotomy with endarterectomy and patchplasty was performed, in one of these patients a shunt was necessary. In 12 twelve patients MES occurred during the dissection before clamping. Eight of these patients belonged to group B and four patients to group A. The mean number of MES during dissection for group A was 2.4 (SD 4.6; 5-15) and for group B 3.9 (SD 7.1; 2-28). There is no statistically significant difference in the Wilcoxon-test; P=0.4375. There was no patient showing reperfusion syndrom or clinical signs of a new cerebral infarction or any other neurological deficit. There were no other major complications like myocardial infarction or death as well as no minor complications like periphereal nerve lesions, bleeding or wound healing disturbance.

In this prospective, randomised trial early control of the distal internal carotid artery did not reduce the occurrence of MES during dissection of the carotid bifurcation. Also, the total number of MES throughout the procedure and postoperatively was comparable between both groups. The procedure related times as well as the clinical outcome did not differ significantly. Thus, early control of the distal internal carotid artery has got no advantage but also no disadvantage as compared to the traditional CEA technique. However, a limitation of the study is the small number of patients included.