| Early Surgical Results of Carotid Endarterectomy. |
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Ham, Hyung Yong , Kim, Tae Sun , Moon, Hyung Sik , Seo, Bo Ra , Jang, Jae Won |
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Department of Neurosurgery, Chonnam National University Hospital & Medical School, Gwangju, South Korea. taesun1963@yahoo.co.kr |
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| Abstract |
OBJECTIVE
S: In this study, we evaluated early surgical results including 30 days early stroke and death rate and complications in 168 cases carotid endarterectomy (CEA). METHODS: A retrospective review of patients who underwent CEA at our institute between September 1999 and August 2010 was done. Preoperative symptoms were stroke in 72 cases, transient ischemic stroke or reversible ischemic neurologic deficit in 56 cases and asymptomatic in 40 cases. Most of the patients had conventional cerebral angiography or neck computed tomography angiography (CTA) for preoperative evaluation. Immediate radiological follow up was performed by neck CTA 1 week postoperatively. RESULTS: The overall postoperative stroke rate including transient ischemic attack within 30 days of the treatment was 1.7%. Major stroke rate with morbidity and death rate within 30 days was 0.6% (1 : major stroke, 1 : death). The cause of death was airway occlusion due to wound hematoma. Cranial nerve palsy developed in two patients (1.1%) and neck hematoma in six patients (3.5%). Neck CTA revealed total occlusion of internal carotid artery in one patient with acute cerebral infarction and then recovered fully. Intracranial hemorrhage relating to the hyperperfusion syndrome developed in one patient. Radiological patency rate was 98.7%. The comparison of 30 days morbidity and mortality rate between CEA and carotid angioplasty and stenting were each 0.6% and 1.5%, but there was no statistical significance. CONCLUSIONS: Carotid endarterectomy provides considerable future risk prevention against stroke in patients with symptomatic and asymptomatic carotid stenosis. |
| Key Words:
Endarterectomy, Carotid, Stroke, Early outcomes |
Introduction
Stroke is the second most common cause of death worldwide, and it is also the second most common cause of death in South Korea, after malignant neoplasm, according to 2006 data from the National Statistics Office.21)
Ischemic stroke accounts for 80% of all cases of stroke and 15~20% of all ischemic strokes are caused by extracranial internal carotid artery stenosis.5)11)23)25)
In 1953, Debakey et al.7) became the first to report a successful carotid endarterectomy (CEA). Since then, CEA has undergone prospective randomized control trials for internal carotid artery (ICA) stenosis, and has become the standard method for the prevention of stroke in patients with severe internal carotid artery stenosis. In 2004, the United Sates Food and Drug Administration approved the use of stent insertion for the treatment of severe carotid artery stenosis with concomitant neurological symptoms in patient with a high risk of CEA. Since then, although stent insertion has been suggested as an alternative to CEA, the role and safety of stent insertion has not been clearly demonstrated. Besides, several studies reported that the incidence rate of early stroke after CEA decreased to about 1% due to the development of a relevant surgical technique.14)17)18)
Also, in South Korea, the number of people diagnosed with carotid artery stenosis is increasing due to increased intake of meat and frequency of medical checkup, although reports on the outcome of the disease are very few.
In this study, the complications and surgical outcomes of CEA, such as the incidence rate of early stroke and consequential mortality within 30 days after the CEA, were investigated by reviewing the 168 cases of CEA that were performed in the past 10 years.
Materials and Methods
A retrospective investigation was conducted of 168 cases that underwent CEA for severe ICA stenosis (i.e., over 70% of the intraluminal diameter stenosed) and symptomatic moderate stenosis (50~69% intraluminal diameter stenosed) from September 1999 to August 2010 at our institute.
Conventional cerebral angiography was performed in most of the patients, and in the remaining, carotid computed tomography angiography (CTA) was done. Cerebral angiography is essential to reveal a hemodynamic condition such as branching pattern of external carotid artery, existence of tandem stenosis, contralateral carotid stenosis, the severity of carotid stenosis and collateral circulations.
The surgical indications of CEA include symptomatic ICA stenosis (70~99% intraluminal stenosis as measured by NASCET criteria), regardless of neurologic deficit, symptomatic moderate ICA stenosis (50~69%) that is not responsive to maximal best medical treatment and asymptomatic severe ICA stenosis (over 70%) found in patients with a low operation risk.
Carotid angioplasty and stenting (CAS) was considered in case of recurrent ICA stenosis after CEA, long segment ICA stenosis, previous extensive neck surgery, radiation induced stenosis, existence of contralateral stenosis and higher risk than operation under general anesthesia. CAS was performed using transfemoral catheterization under local anesthesia. A distal protection device was used with spider FX (ev3 Inc.). Results of CAS were compared with that of CEA.
According to the medical records before the surgery, patients were classified into three groups based on their medical records:stroke group, transient ischemic attack group and asymptomatic group. In addition, the risk factors of the patients and the early complications that developed within 30 days after the surgery were identified based on the patients’ medical records. Patients with symptoms received surgical treatment 4~8 weeks after the symptoms appeared, and a follow-up was made using neck CTA 1 week after the operation.
All the patients kept taking aspirin until the day when the surgery was performed and restarted taking it the day after. After the surgery, each patient was transferred to the neurological intensive care unit for monitoring of neurological change and blood pressure and received intravenous nicardipine, a calcium channel blocker.
CEA was performed under general anesthesia. In some patients who underwent CEA during the early phase of the study period, an electroencephalogram was used for intra?operative monitoring of their nerve, whereas in most of the patients who underwent the surgery after the early phase of the study period, trans-cranial optical spectroscopy was used for intra-operative monitoring. An intraoperative shunt was not used during the surgery, and intravenous heparin (2,000~5,000IU) was administered just before the carotid artery was blocked to prevent acute thrombosis.
Chi-square test was used for statistical comparisons between CEA and CAS.
Results
The average age of the cases was 67.2 years (range:46~87 years). There were 127 males (75.5%) and 41 females (24.5%). The most common preoperative risk factors were hypertension and diabetes. Forty-two (25%) of the cases had coronary artery disease and 128 (76.1%) cases, preoperative neurological symptoms and the stenosed area was most common between cervical vertebrae C3 and C4 (90 patients, 53.5%) (Table 1).
Three cases (1.7%) developed stroke as an early complication within 30 days postoperatively; among them, one had a permanent neurological deficit. In the case of this patient, according to the result of the preoperative conventional cerebral angiography, right ICA stenosis was accompanied with right middle cerebral artery stenosis. Postoperative left hemiparesis developed and brain CT scans revealed acute cerebral infarction in the right middle cerebral artery territory. Cranial nerve (hypoglossal nerve) injury occurred in two cases after CEA and intracranial hemorrhage occurred in one case due to the hyperperfusion syndrome after CAS (Fig. 1). Preoperative cerebral angiography showed that aneurysm was absent. Wound hematoma occurred in the surgery site in six cases (3.5%); one of them died due to acute airway obstruction (Fig. 2). In five of six patients, these hematoma resolved completely within a few days later after conservative treatment. The morbidity rate within 30 days after the operation was 0.6% and also the morbidity rate within 30 days after the operation was 0.6% (Table 2). When comparing two groups (CEA group and CAS group), the CEA group had more superior outcomes than the CAS group. But, there was no statistical significance (Table 2).
Neck CTA that was performed one week after the operation showed that most of the cases (98.7%) maintained a good patency, and only one case had acute obstruction (Table 3). No infection was found in the surgery site.
Discussion
According to North American Symptomatic Carotid Endarterectomy (NASCET) and European Carotid Surgery Trial (ECST), the prospective randomized control studies that were performed in the early 1990s in carotid artery stenosis patients with a history of preoperative neurological symptoms showed early stroke incidence rates of 5.2% and 6% and mortality rates of 0.6% and 1%, respectively, within 30 days after the carotid endarterectomy.2)3)8) In addition, the Asymptomatic Carotid Atherosclerosis Study (ACAS) reported that the postoperative incidence rates of early stroke and mortality were 1.4% and 0.1%, respectively.1)4)15)
Due to the recent development in the interventional procedure for carotid stenosis, CAS is drawing attention as an alternative to CEA for patients with severe carotid stenosis. According to the Endarterectomy Versus Angiography in patients with Symptomatic Severe Carotid Stenosis (EVA-3S) study reported in 2006, however, the incidence rate of stroke and mortality within 30 days after the CEA was 3.9% and the incidence rate of stroke and mortality 30 days after carotid stent insertion was 9.6%.13)16) Moreover, the Nationwide Inpatient Sample (NIS) study, which investigated the results of the CEA performed in 245,045 patients and of the CAS performed in 14,035 patients from 2003 to 2004, showed that CEA was safer with stroke and mortality postoperative incidence rates each of 0.9% and 0.4%, than CAS with stroke and mortality incidence rates of 2.1% and 1.3%, respectively.10)24)26)
The intermediate report on the ongoing International Carotid Stenting Study (ICSS) showed that CEA was the better choice than CAS in patients with carotid stenosis if the other conditions are the same.9)22)
In this study, there was only one case of early death after CEA in the 10-year period, and the early stroke incidence rate was 1.7%, which is similar to the results of other studies. Besides, the incidence rate of postoperative complications such as myocardial infarction, intracranial hemorrhage and cranial nerve injury in this study was considerably lower than that in other studies.
Presently, postoperative cerebral infarction occurred in three cases but permanent neurological deficit was seen in only one case. To prevent cerebral infarction in the perioperative period, all operational procedures should be carefully performed. Arterial wall dissection and exposure should be gently handled and heparin should be appropriately used. In addition, the arterial lumen should be thoroughly examined and washed and coagulation and intraluminal irrigation should be performed, using reflux, just before complete carotid artery suture.
Hypoglossal nerve injury occurred in two cases during CEA. Hypoglossal nerve injury has been known to occur due to venous plexus clotting around the nerve or excessive protraction of the descendens hypoglossi. Thus, complications can be minimized if wide operative fields can be secured by dissecting this nerve from the main hypoglossal nerve.
Myocardial infarction is the most common cause of postoperative mortality in cases who have undergone CEA. Thus, it is critical to evaluate the condition of their cardiovascular system, including the presence of hypertension and coronary artery disease, when evaluating underlying chronic disease and risk factors of patients before surgery. Previous studies showed that patients with both carotid stenosis and coronary artery stenosis were frequently observed and 50% or more of the patients who underwent carotid endarterectomy had significant coronary artery disease.6)19) In the cases who underwent CEA at our hospital, none developed postoperative myocardial infarction. In the other group (66 patients) in which CAS was performed during the same period, the number of cases with coronary artery disease was higher than that of the cases who underwent CEA. This low number of cases with postoperative coronary artery disease could explain why there was no mortality due to postoperative myocardial infarction. Besides, it is believed that risk factors such as systemic disease and administration of an anticoagulant drug (e. g. warfarin) could be critical to the surgical outcome.
The eligible patient group for CAS has been expanded to cover the low-risk patient group because of its non?invasive features.12)20) In our hospital, however, CEA was considered as the first treatment choice for all the cases with carotid artery stenosis and CAS was considered only in patients with a high risk of surgery.
To decide whether or not to perform CAS or CEA, it was important to perform preoperative conventional cerebral angiography in most cases and to identify the degree of carotid stenosis and the hemodynamic condition such as branching pattern of external carotid artery, exist of tandem stenosis, contralateral carotid stenosis, the severity of carotid stenosis and collateral circulations.
As mentioned above, one case who underwent CEA died postoperatively; this case was found to have had acute airway obstruction. In the case of transient stroke, brain CTA showed that the contralateral side of the surgery site was supplying blood to the carotid artery and the patient is being followed up as an outpatient department after the conservative treatment without particular problems (Fig. 3).
The major causes of postoperative ICA occlusion result from technical mistakes but are also associated with heparin-induced hypercoagulopathy or vessel tortuosity in elderly patients. Thrombogenicity of the vessel that underwent endarterectomy is also a contributing factor that can be resolved through the irrigating of the internal wall of vessel during operation.
In this study, CEA was conducted under general anesthesia, which has the advantages of reducing the patient’s fear and of completely controlling the physiological variables such as respiration and blood pressure, with the help of drug administration. It has the disadvantage, however, of relying on an electrical physiological monitoring device for neurologic evaluation. On the other hand, as local anesthesia cannot completely control the patient’s respiration and blood pressure, its role is very restrictive in brain protection. The anesthetic technique should thus be chosen due to its advantages and disadvantages.
Hematoma occurred in the surgery site in six cases (3.5%) and one of them died caused by acute airway obstruction. Surgery site hematoma is considered that have occurred due to the combined effects of the insufficient hemostasis during the exposure of the operation site and the continuous administration of the anti?platelet agent. Thus, more careful hemostasis during surgery is considered necessary.
In this study, early complications within 30 days postoperatively and their results were investigated. Long-term follow-up is required to establish the efficacy of CEA.
Conlcusion
This study of a total of 168 cases who underwent CEA in the past 10 years showed that CEA is safe for the treatment of severe carotid stenosis and for the prevention of stroke. CEA and CAS represent complementary rather than competing modes of therapy because CAS is reserved for use in a disadvantaged subset of high-risk patients owing to anatomic risk factors or medical comorbidities. In addition, long-term follow-up is necessary for patients with a high risk of surgery.
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