site. The common carotid artery has been looped with a yellow vascular sling. A hypoplastic external carotid artery is branching off in the medial direction (top). The internal carotid artery is marked with a black arrow (<). The hypoglossal nerve (*) crosses the internal carotid artery.
Thromboendarterectomy (TEA)
In classic TEA of the internal carotid artery, following clamping and dissection of the carotid bifurcation (Fig. 1.1-20a), a longitudinal arteriotomy is carried out on the anterolateral wall of the carotid bifurcation and is extended into the common and internal carotid artery. Using a dissector, the endarterectomy is then carried out, and any distal intima layers that may be present are fixed with a single or continuous attachment suture (polydioxanone 7–0). If there is significant stenosis of the external carotid artery, an EEA can also be carried out. The disengaged plaque is further smoothly transected proximally, in the common artery, preferably with scissors. After copious rinsing of the endarterectomized vascular segment and checking for possible residual tissue and thrombus, an alloplastic patch (polyester, Dacron, or expanded polytetrafluoroethylene) is trimmed to size and sutured in with a continuous nonresorbable monofilament suture (polypropylene, Prolene 5–0) (Fig. 1.1-20b, c). In delicate vessels, a patch obtained from autologous great saphenous vein can also be used. Comparative studies have not shown that autologous venous patches confer any significant advantages in comparison with alloplastic materials in routine use (Bond et al. 2004; Naylor et al. 2004) (Fig. 1.1-20c).
When there is symptomatic coiling or kinking, shortening can be carried out either with segmental resection of the internal carotid artery or proximalization (transposition) of the origin of the internal carotid. The advantage of TEA is that it provides a good overview of the operative vascular segment and of the distal layer of the intima. This allows safe treatment, particularly for long stenoses. In addition, it is technically easier to introduce a temporary shunt. However, the procedure is more time-consuming and usually leaves foreign material (the patch) in the artery.
Fig. 1.1–20a-c (a) Positioning of clips on the carotid artery before the arteriotomy. (b) Longitudinally arteriotomized common and internal carotid artery. An intraluminal shunt has been introduced. A Dacron patch is being sewn in with a continuous suture. (c) The Dacron patch has been sewn in with a continuous suture.
Eversion endarterectomy (EEA)
In EEA, after clamping of the carotid bifurcation, transection of the internal carotid is carried out directly at its origin in the bifurcation. The correct dissection level is identified at the level of the external elastic lamina between the media and the intima before the internal carotid is rolled from inside out and the stenotic plaque is removed (Fig. 1.1-21a). At the distal end of the plaque, which usually terminates smoothly, the plaque cylinder normally breaks off without leaving a flap (Fig. 1.1-22). The internal carotid artery is rolled back into its original position and is then reattached with a resorbable monofilament continuous suture (polydioxanone 5–0) (Fig. 1.1-21b). To prepare a longer anastomosis, the arteriotomy can be extended cranially to a length of 15–30 mm in the internal carotid or proximally at the common carotid. Plaque removal of the bulb or of the common and external carotid artery can be carried out in the form of an open TEA or as an EEA at the external carotid artery. If a relevant distal intimal flap appears in the internal carotid, it can be secured with single fixation sutures stitched from the outside (tack sutures).
The technical advantage of EEA lies in the much shorter operating time required and the fact that there is no foreign material in the artery, provided resorbable suture material is used for reinsertion (Fig. 1.1-21c). As carotid stenoses often only appear in the bulb and in the area of the origin of the internal carotid, the limited extent of the vascular segment opened during eversion is usually adequate. EEA also makes it possible to correct symptomatic coiling or kinking of the internal carotid artery much more easily using a shortening operation than with TEA; either a segment of the internal carotid is resected, or a longer, proximalized anastomosis can be created if there is only slight coiling. The EEA procedure only becomes more difficult in longer lesions or in extracranial tandem stenoses. Introducing a temporary shunt is also slightly more complicated. In this case, it is best to start with the suture in the internal carotid artery and to introduce the shunt only after the side further away from the surgeon has been completed.
The current data show that there are no relevant differences between the TEA and EEA procedures with regard to postoperative mortality, morbidity, or recurrent stenoses (Cao et al. 2004; Crawford et al. 2007).
Intraoperative neuromonitoring and temporary intraluminal shunt
To prevent procedure-related cerebral ischemia during CEA, systolic blood pressure should be raised to > 150 mmHg if possible and systemic heparinization with 50–100 IU heparin/kg body weight is obligatory.
Fig. 1.1–21a-c (a) The surgical site in eversion endarterectomy of the internal carotid artery. The internal carotid artery has been transected obliquely at the common carotid artery. A dissection cylinder has been spatulated at the dissection level in the area of the external elastic membrane. The adventitia is now rolled up cranially until the cranial end of the dissected part tears spontaneously. (b) Reinsertion of the internal carotid artery into the common carotid artery using a continuous suture. (c) The surgical site after completion of the eversion endarterectomy.
Fig. 1.1–22 The dissection specimen after eversion endarterectomy of the internal carotid artery. The arrow tip (<) marks the residual lumen of the artery before disobliteration.
The most reliable method of intraoperative neuromonitoring involves assessment of changes in the state of consciousness and in motor activity in cooperative, conscious patients under regional anesthesia. These two checks can be carried out before and after clamping of the carotid artery by speaking to the patient and using rhythmic activation of a toy in the contralateral hand. If clouding of consciousness or loss of motor control immediately after clamping of the carotid artery occurs at high normal blood-pressure values, a temporary intraluminal or extraluminal shunt (e.g., a Javid or Pruitt shunt) should be placed. However, if the symptoms only occur after a latency period of several minutes, it is advisable—depending on the progress of the operation—either to complete the surgery quickly or to introduce a shunt. Optional shunt placement is needed in 5–10% of cases (BQS-Bundesauswertung 2007).
For placement of a temporary shunt in patients undergoing surgery with general anesthesia, there are basically two different approaches that have developed:
