Carotid endarterectomy surgery methods
1.Standard CEA (sCEA): The patient is placed in a supine position with the head to the opposite side, and a straight incision is made in front of the sternocleidomastoid muscle. If the lesion is high, the upper edge of the incision should be turned posteriorly along the mandibular rim to avoid damaging the mandibular rim branch of the facial nerve, and the skin, subcutaneous and broad carotid muscles are incised in turn. The common carotid artery, internal carotid artery and external carotid artery were exposed, and the superior thyroid artery, external carotid artery, internal carotid artery and common carotid artery were blocked respectively.
The common carotid artery and the wall of the internal carotid artery were dissected longitudinally, the intima and plaque were removed, the superior thyroid artery, the external carotid artery, the internal carotid artery and the common carotid artery were blocked, the internal carotid artery was dissected transversely along the beginning of the internal carotid artery, the plaque and the vessel wall were separated circumferentially along the circumference of the internal carotid artery, the wall of the internal carotid artery was lifted, the intima and plaque were removed with a stripper, and the wall of the internal carotid artery was dissected upward like a sleeve. The internal carotid artery wall was separated upward like a sleeve to the migrating part of the plaque and normal intima, and the plaque was sharply cut off and removed, and then the internal carotid artery was anastomosed end-to-end to the original incision.
sCEA is the basis and standard of CEA and has a wider scope of application. sCEA is still one of the most important surgical procedures in China and abroad, although patching techniques and reversal CEA were introduced later.
2.Flipped carotid endarterectomy (eCEA): After blocking the superior thyroid artery, external carotid artery, internal carotid artery and common carotid artery respectively, the internal carotid artery is cut off transversely along the beginning of the internal carotid artery, the plaque and vessel wall are separated circumferentially along the circumference of the internal carotid artery, the wall of the internal carotid artery is lifted, and the intima and plaque are peeled off with a stripper, and the wall of the internal carotid artery is separated upward like a sleeve, until The plaque and the normal intima were sharply cut off to remove the plaque, and then the end-lateral anastomosis of the internal carotid artery was made to the original incision.
The procedure is completed by sequential suturing of the incision. eCEA has the advantage of avoiding incision and suturing of the distal internal carotid artery, which may reduce the rate of restenosis due to suturing.
3. Patch-forming repair technique: In sCEA, surgeons are concerned about postoperative loss of canal diameter or distal restenosis due to the technique of sequential suturing, so patch-forming repair techniques are used. The patches used include intravenous patches and synthetic materials, etc. After removal of the plaque by sCEA, one end of the patch is fixed to the upper edge of the incision, and then successive sutures are made separately.
4.Modified flipped carotid endarterectomy: Kumar et al. modified flipped CEA by first cutting the artery longitudinally from the proximal segment of the common carotid plaque to the fork of the internal carotid bulb, without cutting the internal carotid artery transversely and directly flipping and peeling the plaque, which also achieved better efficacy, but in the actual operation, the operation is not easy.
5. The purpose of the diversion technique required in CEA surgery is to maintain a certain amount of cerebral blood flow after blocking the carotid artery, so as to avoid cerebral infarction caused by the block.
5.1 Choice of diversion or not: The need for diversion during CEA is controversial. It is recommended that the need for diversion be determined by effective intraoperative monitoring, for example, if TCD monitoring shows that ipsilateral middle cerebral artery flow is reduced to less than 50% after arterial blockade, the use of diversion techniques is recommended.
Some scholars use diversion in all cases, but there is a risk that the diverter tube may damage the intima of the artery; others do not perform diversion in all cases and replace it with a significant increase in blood pressure, but there is evidence that large intraoperative changes in blood pressure may cause damage to the patient’s cardiac function, which is potentially risky.
5.2 Diversion technique: Placement of a diversion is generally done after the artery has been blocked and dissected with the common carotid end placed first, followed by the internal carotid end after the diversion tube has been vented. And before the end of the artery is sutured, the diversion tube is removed, then the arterial lumen is ventilated, and finally the remaining few stitches are sutured.
6. Regarding the choice of several surgical procedures: Although there are several surgical procedures, in general, each method has its own strengths. The surgical technique itself is not advanced or not, but the key is to individualize the choice for the specific situation of the patient.
6.1 sCEA versus eCEA: Data from Shah et al. between 1993 -1998 showed that eCEA did not result in the distal canal reduction seen after sCEA. eCEA had lower complication rates than sCEA, including mortality and neurological deficit rates, and more importantly, follow-up revealed a restenosis rate of 0.3% for eCEA versus 1.1% for sCEA. This study, together with the prospective study by KoskasU and Entz et al, confirmed the advantages of eCEA.
However, a review of the literature by Cao et al. showed that although eCEA may be useful in reducing restenosis rates, it does not significantly improve stroke or death in patients, and because of the small number of cases, it still cannot prove superiority over sCEA. eCEA, on the other hand, has some technical limitations, such as longer suture operation time and difficulty in externalizing the suture during end-lateral anastomosis. In addition, eCEA is difficult to remove all plaques in patients with extensive involvement of the common carotid artery.
Also, because eCEA is a transection of the bifurcation of the internal carotid artery, and because the internal carotid artery needs to be separated along the entire circumference due to the need for external rotation, the carotid sinus nerve is likely to be severed, thus damaging the pressure receptors and losing the pressure perception reflex, resulting in postoperative {blood pressure or uncontrollable blood pressure fluctuations. Some studies have found that eCEA patients are prone to sympathetic excitation after surgery, leading to increased hypertension, pulse pressure and heart rate, and even after an average of 9.5 months of interim follow-up, some eCEA patients still require higher doses of antihypertensive medication.
6.2 sCEA and patchplasty: There are many studies on patchplasty in sCEA, and most of the literature supports the use of patches intraoperatively. One meta-analysis showed that patch repair reduced perioperative stroke, occlusion, and postoperative restenosis rates, and therefore patch revascularization has been consistently recommended in recent eSVS and ASVS guidelines.
First, the increased time and difficulty of the procedure may inadvertently increase the risk to the patient; second, the ideal patch material does not exist; venous patches that are too thin may rupture, and synthetic materials carry the risk of infection.
Therefore, patch angioplasty should be viewed objectively, after all, the relevant studies are older and the current guideline recommendations are based on these studies, but the surgical details and perioperative treatment at that time were not very satisfactory, while the development in the last 20 years, drugs can play a positive role in preventing acute occlusion and restenosis after CEA.
7. Micro carotid endarterectomy (Micro-GEA): Micro CEA surgery is a product of the combination of modern microscopy and surgical techniques. Compared with CEA under the naked eye or under surgical magnification, Micro-CEA has many advantages. Second, the relationship between the layers of the arterial wall and the plaque can be clearly distinguished under the microscope, which makes the separation very clear and easy.
Thirdly, the distal endothelium of the internal carotid artery can be handled more delicately. Under the microscope, the migrating part of the plaque and the normal endothelium can be clearly distinguished, and the distal endothelium can be sharply cut and trimmed without additional stapling, which reduces the possibility of postoperative thrombosis or entrapment; fourthly, during the suturing process, the stitch distance is smaller and the suturing is more meticulous, and it is possible to avoid bringing the outer membrane tissue into the anastomotic margin, which reduces the possibility of postoperative thrombosis or distant restenosis. This reduces the possibility of postoperative thrombosis or distant restenosis.
Although some clinical studies have shown the advantages of Micro-CEA, Micro-CEA is currently limited to neurosurgeons due to the additional training and equipment required, and there are still differences between microscopic and visual or surgical magnification procedures.
8. Discussion related to the surgical approach: For CEA, the anatomical landmarks are clear and the levels are simple and not complicated to evaluate from a purely technical point of view, but there are still some questionable issues regarding the surgical approach due to various variations or other factors.
8.1 Longitudinal or transverse incision: CEA generally chooses a longitudinal incision at the anterior border of the sternocleidomastoid muscle, which has the advantage of easily exposing the mandibular and sternal angles, and can be applied for both {low and low level surgery, but the postoperative scar is very unattractive; whereas the transverse incision is made along the texture of the skin of the neck, which can maintain aesthetics but in case of extensive lesions or intraoperative need to use diversion The exposure is limited when the lesion is extensive or when intraoperative diversion is required. The choice between the two types of incisions is generally individualized based on the patient’s condition and the surgeon’s experience.
8.2 Medial or lateral jugular access: After the broad jugular dissection, the general choice is to expose the carotid bifurcation through the medial internal jugular vein, ligating the transverse branches from the internal and external jugular veins along the way and exposing the hypoglossal nerve to prevent damage to it, exposing the jugular collaterals, which can also be cut if necessary, exposing the sternocleidomastoid artery, vagus nerve, etc.
The lateral approach to the jugular vein can also be chosen, also from the anterior border of the sternocleidomastoid muscle, during which the internal jugular vein is pulled medially and 1-2 small branches from the sternocleidomastoid muscle may converge laterally from the internal jugular vein.
In comparison between the two approaches, the lateral approach to the internal jugular vein provides better exposure of the anterior and distal internal carotid artery. At the same time, it is easy and fast to operate without dealing with the transverse branches of the jugular vein, and it is generally not necessary to expose the hypoglossal nerve, thus reducing the chance of its injury, but there is a possibility of increasing hoarseness due to the strain on the vagus nerve.
8.3 Posterior cervical triangle approach: It is mainly aimed at the exposure of high CEA and can expose the internal carotid artery to the level of the first cervical vertebra. A straight incision is made at the posterior border of the sternocleidomastoid muscle, and care is taken not to damage the superficial auricular nerve and the lesser occipital nerve when performing subcutaneous separation; the paramedian nerve needs to be carefully separated during surgery, and the internal jugular vein and sternocleidomastoid muscle are pulled forward together to expose the carotid bifurcation; to prevent damage to the vagus nerve, it can be kept posterior to the carotid artery, and if necessary, it can be freed and moved anteromedially to prevent damage to the superior laryngeal nerve.