Carotid Cross-Clamp intolerance during carotid endarterectomy in regional anesthesia

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Introduction

Carotid endarterectomy (CEA) is a safe and effective treatment for preventing stroke in patients with significant internal carotid stenosis [1-3]. This method is associated with lower perioperative stroke compared to interventional stenting [2-6].   

During the surgical endarterectomy, carotid cross clamping is needed for arteriotomy and plaque removal. Carotid cross clamping reduces the bool flow to the circle of Willis and some patients show intolerance to the temporary occlusion of internal carotid artery [7-9]. In this case the use of a temporary shunt is necessary. Locoregional anesthesia has been the first choice in our department since 2019.

The aim of this study is to demonstrate the safety of the locoregional anesthesia in patients with carotid cross clamping intolerance (CCI) and the risk factors that predict this condition. 

Material and methods

All patients who underwent surgical carotid endarterectomy between January 2019 and December 2020 were identified in a retrospective review and analysis of a prospectively maintained database. The degree of internal carotid artery (ICA) stenosis and consequently surgical treatment followed the European Carotid Surgery Trial (ESCET) [10]. The Indication for surgical treatment was made for a stenose of ICA between 70% to 99% or in case of symptomatic stenosis.

Technique of locoregional anesthesia

To perform the superficial cervical Plexus Block we rotate the head of the patient approximately 45 to 60 degrees to the contralateral side. By slightly lifting the head in this position the posterior border of the sternocleidomastoid muscle can be identified. The first injection site is located halfway between the mastoid process and the clavicle on the posterior edge of the sternocleidomastoid muscle at the punctum nervosum (Erb´s point). After a local anesthetic skin wheal (3 ml Mepivacaine 1%) the needle is positioned 1 cm to 2 cm below the sternocleidomastoid muscle to inject the rest of the Mepivacaine 1% (7ml). This is followed by a subcutaneous infiltration (up to 40 ml Ropivacaine 0,5% / max. 3mg per kilogram body weight) starting from the initial injection site in the direction of the mastoid, the clavicle and the anterior border of the sternocleidomastoid muscle. To complete the subcutaneous infiltration the second injection site is located at the anterior border of the sternocleidomastoid from which the injection goes to cranial and caudal. Due to the use of a retractor in the area of ​​the lower jaw, which is often perceived as painful, the last injection is made from the angle of the jaw along the mandible.  Any needle positioning must be done under aspiration to avoid intravenous administration of the local anesthetic.

Surgical technique

An incision is made at the front edge of the sternocleidomastoid muscle and the common carotid artery (CCA) is identified and isolated from surrounding tissues with sharp dissection and continuing toward the bifurcation. Now the internal and external carotid arteries can be isolated too. Heparin (5.000U) is administrated intravenously and the systolic arterial pressure is increased and kept over 160 mmHg. In the next step the cross-clamping tolerance test for 60 second is performed. During clamping, the patient is neurologically meticulously observed. In case of cross clamping intolerance, the operation is proceeded with the insertion of a temporary shunt. The arteriotomy is started in the common carotid artery and continuing to the internal carotid artery. The plaque is completely removed and the arteriotomy incision is covered with a patch. Before completing the suture, the clamps are partially removed to flush out the debris using the blood flow. Now the external and common artery can be released and finally the clamp of internal carotid artery ca be removed.

Statistical analysis

Continuous variables are described as mean and standard deviation and compared with the Student’s t-test. The chi- squared and Fisher’s exact tests is used for comparing the categorial variables. The threshold of statistically significant difference was p<0.05. The statistical analyses were performed using the IBM SPSS statistical software (version 24; IBM Corporation, Armonk, NY, USA).

Results

During a period from January 2019 to December 2020, 53 patients were identified and included for further analysis. Of the recruited patients,29 were male. The baseline characteristic and risk factors are shown in table I. As we see the arterial hypertension followed by CAD are the most frequent risk factors.

Eight patients (15%) had cross-clamping tolerance test intolerance and in all these cases the surgical procedure was continued with shunt. The further course of the operation remained uncomplicated. The in-hospital mortality was nil and only in one case a transient ischemic attack occured. The result of the univariate regression analysis is presented in table II. Coronary artery disease [odds ratio (OR) 12.65, 95 % CI 1.43–112.50], History of cerebrovascular events [odds ratio (OR) 10.50, 95 % CI 1.83–60.30] and contralateral stenosis of 70% and more [odds ratio (OR) 26.66, 95 % CI 2.29–304.37] presented significant association to the cross-clamping intolerance and the need to shunt. The remaining factors showed no significant association to the intolerance.

Discussion

The carotid endarterectomy is a safe method for preventing stroke in case of internal carotid stenosis. But we know that the carotid cross clamping cannot be tolerated by all the patients. The incidence of cross-clamping intolerance is estimated to be between 7 to 30 % [1]. In our cohort this incidence was15%. The major benefit of locoregional anesthesia is the continuous neurological monitoring of awake patients. The locoregional anesthesia gives us the opportunity to identify the patients who needs a shunt. In all cases we could proceed the open surgical procedure using an arterio-arterial shunt. This method can be particularly difficult in restless patients. Lutz et al. [10] described the carotid endarterectomy in locoregional anesthesia as a safe method with better neurological outcomes. A currently meta-analysis comparing LA with GA showed that LA was associated with significantly less stroke, cardiac complication, and hospital mortality [12]. Our study presented only one transient attack but no stroke or mortality. Some factors that predict cross clamping intolerance are previously discussed in a few literatures. Pifretti et al. [7] identified hypertension and symptomatic lesions as significant predictors, whereas Kretz et al. [13] described renal insufficiency and contralateral carotid occlusion as predicting factors for the clamp intolerance.

We found that Coronary artery disease, history of cerebrovascular events and contralateral stenosis of 70% and more, as significant factors to predict cross clamping intolerance. Other factors remain without significant association.

At this point the importance of the circle of Willis must be mentioned. Statistically significant association between cross clamping intolerance and agenesia in the circle of Willis is reported [8, 9].

The simple size of our study is the main limitation. In addition, the investigating of the circle of Willis could give us more information.

Conclusion

Regional anesthesia is a safe method for identifying patients with CCI and safely performing the surgical procedure. Contralateral stenosis of the ICA and a history of cerebrovascular events are significant factors for predicting CCI.

Data are presented as n (%) for categorical variables and median (range) for continuous variables.

Table 1: Descriptive characteristics of the included patients

Variable	Value (n=53)
Age (median with range)	78 (56-90)
Male/ Female	29 (54.7%) / 24(45.3%)
Diabetes	14 (26.4%)
Hypertension	45 (84.9%)
Coronary artery disease	23 (43.4%)
History of cerebrovascular events	16 (30.2%)
Renal insufficiency	10 (18.9%)
Dyslipidaemia	30 (56.6%)
Chronic obstructive pulmonary disease	5 (9.4%)
Smoking history	20 (37,7%)

 

Table 2: Logistic regression analysis of potential factors associated with perioperative shunt requiring

Variable	OR	Lower limit	Upper Limit	P value
Age	0.98	0.90	1.07	0.627
Female	4.50	0.82	24.83	0.121
Diabetes	0.35	0.039	3.149	0.333
Hypertension	1.29	0.14	12.17	0.824
Coronary artery disease	12.69	1.43	112.50	0.006
History of cerebrovascular events	10.50	1.83	60.30	0.003
Renal insufficiency	1.54	0.26	9.08	0.630
Dyslipidaemia	0.40	0.09	1.89	0.237
Chronic obstructive pulmonary disease	1.46	0.14	15.10	0.574
Smoking history	0.50	0.09	2.26	0.420
Contralateral stenosis over 70%	26.66	2.29	304.37	0.009
Symptomatic lesion	3.90	0.73	20.71	0.124

Additional Info

Conflict of interests. The authors declare no actual and potential conflict of interests which should be stated in connection with publication of the article.

Participation of authors. P. Majd, P. Galkin, M. Tayeh, T. Herzmann, M. Gores, E. Kalmykov, W. Ahmad – research concept and design, material collection and processing, statistical analysis, text writing, editing.

About the authors

Payman Majd

Evangelical Hospital Bergisch Gladbach

Email: mir.majd@uk-koeln.de
ORCID iD: 0000-0002-5835-8318

Chief physician, Specialist in surgery, Specialist in vascular surgery, Endovascular surgeon

Germany, Bergisch Gladbach North Rhine-Westphalia, Germany

Peter Galkin

Evangelical Hospital Bergisch Gladbach

Email: p.galkin@uk-koeln.de
ORCID iD: 0000-0003-2666-5337

Senior physician Dr. Med., Specialist in vascular surgery

Germany, Bergisch Gladbach North Rhine-Westphalia, Germany

Mahmoud Tayeh

Evangelical Hospital Bergisch Gladbach

Email: m.tayeh@uk-koeln.de
ORCID iD: 0000-0001-5460-8562

Assistant Doctor

Germany, Bergisch Gladbach North Rhine-Westphalia, Germany

Thomas Herzmann

Evangelical Hospital Bergisch Gladbach

Email: t.herzmann@uk-koeln.de
ORCID iD: 0000-0002-7442-9825

Germany, Bergisch Gladbach North Rhine-Westphalia, Germany

Michael Gores

Evangelical Hospital Bergisch Gladbach

Email: m.gores@uk-koeln.de
ORCID iD: 0000-0002-1015-3698

Germany, Bergisch Gladbach North Rhine-Westphalia, Germany

Egan Kalmykov

Evangelical Hospital Bergisch Gladbach

Author for correspondence.
Email: info@helios-international.com
ORCID iD: 0000-0001-6784-2243

MD, PhD

Germany, Bergisch Gladbach North Rhine-Westphalia, Germany

Wael Ahmad

University Hospital of Cologne

Email: wael.ahmad@uk-koeln.de
ORCID iD: 0000-0001-5090-3468

Germany, Cologne North Rhine-Westphalia, Germany

References

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