Contralateral internal carotid artery occlusion impairs early but not 30-day stroke rate following carotid endarterectomy

Oxidative Stress and Total Antioxidant Status During Internal Carotid Artery Clamping with or without Shunting: An Experimental Pilot Study

Background

The exact role of shunting during carotid endarterectomy remains controversial and unclear. The aim of this experimental study was to investigate to what degree carotid clamping may induce changes in the cerebral oxidative status and to focus on the relation of these changes with shunt insertion.

Material/Methods

Forty New-Zealand rabbits were randomized into 4 groups: group 1 classifying animals with carotid shunt and patent contralateral carotid artery; group 2 shunt and occlusion of the contralateral carotid artery; group 3 no-shunt and patent contralateral carotid artery; and group 4 no-shunt and occlusion of the contralateral carotid artery. Blood samples were collected from the ipsilateral internal jugular vein, immediately after carotid clamping (time 0), and then at 5, 10, 15, 30, and 60 minutes afterwards. Evaluation of oxidative stress was accomplished by measuring the lag-time, representing the initial phase of oxidation, rate of accumulation (RA), showing concentration of free oxygen radical and total antioxidant status (TAS) representing antioxidant composition of serum.

Results

Lag-time was significantly different in time points 0, 30 and 60 minutes within each different group. TAS was significantly different in time points 0, 15 and 60 min and RA in time points 0, 5, 10 and 60 min within each different group. 60 minutes after carotid clamping, the rate of accumulation as well as lag-time and TAS were increased in all groups, independently of using or not shunting or the presence of contralateral occlusion. After comparing groups 1, 2 and 3 regarding lag-time, TAS and RA, we did not find statistical difference among the groups at any time point. On the contrary, groups 1, 2 and 3 did show significantly different values comparing to group 4 after 60 min of occlusion.

Conclusions

Our experimental work based on cerebral metabolism found a significantly higher oxidative stress in models with contralateral carotid occlusion. The use of shunt in all other models did not have any influence on oxidative response. Future human studies should focus on the relation of oxidative status and shunt insertion to determine the benefit of selective or routine shunting during CEA.

The influence of contralateral occlusion on results of carotid interventions from the Society for Vascular Surgery Vascular Registry

OBJECTIVE

Data on the influence of contralateral carotid occlusion (CCO) on carotid endarterectomy (CEA) are conflicting and are absent for carotid artery stenting (CAS). This study evaluated the influence of CCO on CEA and CAS.

METHODS

We evaluated patients with and without CCO in the Society for Vascular Surgery Vascular Registry. Primary outcome was a composite of periprocedural death, stroke, or myocardial infarction (MI) (major adverse cardiovascular events [MACE]) and its individual components. Further analysis was done to identify the influence, if any, of symptom status on outcomes.

RESULTS

There were 1128 CAS and 666 CEA patients with CCO. CAS patients were more often symptomatic with a greater incidence of coronary artery disease, congestive heart failure, diabetes, chronic obstructive pulmonary disease, and New York Heart Association class >III. Absolute risk of periprocedural MACE (2.7% for CAS vs. 4.2% for CEA), death (1.1% for CAS vs. 0.7% for CEA), stroke (2.1% for CAS vs. 3.1% for CEA), and MI (0.3% for CAS vs. 0.6% for CEA) was statistically equivalent for both. This equivalence was maintained when patients with CCO were segregated according to symptom status and after adjusting for periprocedural risk. There were 16,646 patients without contralateral occlusion (5698 CAS; 10,948 CEA). Patients without contralateral occlusion with CEA have better outcomes in periprocedural MACE (1.8% for patients without contralateral occlusion vs 4.2% for patients with CCO), and stroke (1.1% for patients without contralateral occlusion vs. 3.1% for patients with CCO) (P < .0001 for both). In CAS patients, CCO did not significantly affect periprocedural MACE (3.2% for patients without contralateral occlusion vs. 2.7% for patients with CCO), death (0.8% for patients without contralateral occlusion vs. 1.0% for patients with CCO), stroke (2.3% for patients without contralateral occlusion vs. 2.1% for patients with CCO), or MI (0.6% for patients without contralateral occlusion vs. 0.3% for patients with CCO). In CEA patients, CCO increased MACE, primarily by increasing stroke rates in asymptomatic (0.7% vs. 2.0%; P = .0095) and symptomatic (1.7% vs. 4.9%; P = .0012) patients.

CONCLUSIONS

Although CEA is preferred in patients without contralateral occlusion, regardless of symptom status, based on lower rates of periprocedural MACE, death, and stroke, the benefit of CEA is lost in patients with CCO because of increased stroke rates in CCO patients after CEA but not after CAS regardless of symptom status. The results of CAS and CEA in patients with CCO are equivalent and within acceptable American Heart Association guidelines.

Diagnosis of and treatment for symptomatic carotid stenosis: an updated review

Carotid stenoses of ≥50% account for about 15-20% of strokes. Their degree may be moderate (50-69%) or severe (70-99%). Current diagnostic methods include ultrasound, MR- or CT-angiography. Stenosis severity, irregular plaque surface, and presence of microembolic signals detected by transcranial Doppler predict the early recurrence risk, which may be as high as 20%. Initial therapy comprises antiplatelets and statins. Benefit of revascularization is greater in men, in older patients, and in severe stenosis; patients with moderate stenoses may also profit particularly if the plaque has an irregular aspect. An intervention should be performed within <2 weeks. In large randomized studies comparing endarterectomy and stenting, endovascular therapy was associated with a higher risk of periprocedural stroke, yet in some studies, with a lower risk of myocardial infarction and of cranial neuropathy. These trials support endarterectomy as the first choice treatment. Risk factors for each of the two therapies have been indentified: coronary artery disease, neck radiation, contralateral laryngeal nerve palsy for endarterectomy, and, elderly patients (>70 years), arch vessel tortuosity and plaques with low echogenicity on ultrasound for carotid stenting. Lastly, in direct comparisons, a contralateral occlusion increases the risk of periprocedural complications in both types of treatment.