In most cases, the internal carotid, external carotid, superior thyroid, and common carotid are occluded separately. The internal carotid is clamped before the external or common carotid to minimize the risk for cerebral embolization. It is important to have created adequate exposure of both the internal carotid and common carotid beyond the diseased portions so that the clamps can be safely applied in locations that will not interfere with obtaining adequate end points of the endarterectomy. The arteriotomy can be initiated on either the common carotid or internal carotid in areas away from the most severe disease. The arteriotomy should be performed on the lateral aspect of the internal and common carotid (i.e., so that the arteriotomy is directly opposite the orifice of the external carotid) (Fig. 9.5A). Having the incision on this most convex aspect of the vessel reduces the chance of having distortion or kinking after closure.
The correct endarterectomy plane is in the outer media, leaving only undiseased circular muscle fibers and the adventitia.
Some surgeons routinely place an indwelling shunt to maintain cerebral perfusion during the endarterectomy (Fig. 9.5B). Only 5% to 10% of patients actually have inadequate collateral flow and experience significant ischemia during the period of clamping.
Because placing an indwelling shunt interferes with the endarterectomy and adds a small risk for intimal damage proximal or distal to the endarterectomy site, many surgeons prefer to shunt selectively. Selective shunting requires some form of cerebral perfusion or collateral flow monitoring. The most common forms of monitoring include performing the procedure under regional or local anesthesia so that neurologic testing of the awake patient can be performed, using intraoperative electroencephalogram monitoring, or measuring internal carotid back pressure (with the common and external carotid clamped) as an indicator of adequate collateral flow. I prefer to perform the procedure under a cervical block and insert a shunt only if the patient develops a neurologic deficit with clamping.
Begin the endarterectomy in the proximal internal carotid and completely separate the plaque from the vessel wall proximally before attempting to create the internal carotid
P.74 end point (Fig. 9.5C). Do not continue in the same plane all the way to the end point because this results in elevation of the more normal intima distally. Usually, the best way to achieve a good end point is to pull the plaque in a proximal direction, allowing the diseased portion to separate (Fig. 9.5D). It may be necessary to remove any residual plaque or intima that is not adherent. Only rarely is it necessary to â!œtackâ!!
the intima distally with sutures.
Create the common carotid end point by elevating the plaque proximally, stopping at a point beyond the most severe disease. The common carotid usually has thickened intima, and the disease does not â!œfeather outâ!! as it does in the internal carotid.
Sharply divide the plaque proximally (Fig. 9.5E). Ascertain that the remaining proximal intima is adherent. Although it seems counterintuitive, the proximal end point can elevate despite the apparent direction of blood flow. This lifting of a proximal end point intimal flap has been observed on ultrasound evaluation and is a potential source of thromboembolism or recurrent stenosis.
External carotid â!œeversionâ!! endarterectomy is facilitated by having completed the common and internal carotid end points first. Separate the plaque from around the orifice of the external carotid. Then, by simultaneously pulling â!œoutâ!! on the plaque and using the clamp or a forceps to push the distal external carotid â!œinâ!! toward the orifice, evert the plaque and feather it to a good end point (Fig. 9.5F).
After completing the endarterectomy, remove any loose intimal fronds and check the end points for adherence. There is evidence that patch closure of the endarterectomy site is superior to primary closure with respect to lower postoperative neurologic events and later recurrent stenosis. Patch angioplasty can be performed with either a fabric patch or autologous vein. Begin patch closure distally and complete it with
monofilament suture in a continuous fashion (Fig. 9.5G). A single suture can be used or a second suture begun at the proximal end.
P.75 Figure 9-5 Endarterectomy
Before completing closure, temporarily release each clamp individually to â!œflush outâ
!! any residual debris. Restore flow into the external carotid circulation first (removing the internal carotid clamp last) to minimize the possibility of cerebral embolization of any residual debris or air.
Close the wound in two layers with continuous absorbable suture. The only deep layer that needs to be approximated is the platysmal layer. A continuous subcuticular skin closure with absorbable suture provides an excellent cosmetic result in most patients.
References
1. Abu Rahma AF, Khan JH, Robinson PA, et al. Prospective randomized trial of carotid endarterectomy with primary closure and patch angioplasty with saphenous vein, jugular vein, and poly-tetrafluoroethylene: perioperative (30 day) results. J Vasc Surg. 1996;23:998â!“1006.
2. Barnett HJM, Taylor DW, Eliasziw M, et al. Benefit of carotid endarterectomy in patients with symptomatic moderate or severe stenosis. N Engl J Med.
1998;339:1415â!“1425.
3. European Carotid Surgery Trialists' Collaborative Group. Randomised trial of endarterectomy for recently symptomatic carotid stenosis: final results of the MRC European Carotid Surgery Trial (ECST). Lancet. 1998;351:1379â!“1387.
4. Executive Committee for the Asymptomatic Carotid Atherosclerosis Study.
Endarterectomy for asymptomatic carotid artery stenosis. JAMA. 995;273:1421â
!“1428.
5. Jackson MR, Clagett GP. Use of vein or synthetic patches in carotid
endartectomy. In: Loftus CM, Kresowik TF, ed. Carotid Artery Surgery. New York:
Thieme Medical Publishers; 2000: 281.
6. Kresowik TF, Bratzler D, Karp HR, et al. Multistate utilization, processes, and outcomes of carotid endarterectomy. J Vasc Surg. 2001;33:227â!“235.
7. Kresowik TF, Hoballah JJ, Sharp WJ, et al. Intraoperative B-mode
ultrasonography is a useful adjunct to peripheral arterial reconstruction. Ann Vasc Surg. 1993;7:33â!“38.
8. Mayberg MR, Wilson SE, Yatsu F, et al. for the Veterans Affairs Cooperative Studies Program 309 Trialist Group. Carotid endarterectomy and prevention of cerebral ischemia in symptomatic carotid stenosis. JAMA. 1991;273:1421â!“1428.
9. North American Symptomatic Carotid Endarterectomy Trial Collaborators.
Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. N Engl J Med. 1991;325:445â!“453.
Authors: Scott-Conner, Carol E. H.; Dawson, David L.
Title: Operative Anatomy, 3rd Edition Copyright ©2009 Lippincott Williams & Wilkins
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