Acute Carotid Occlusion

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Introduction

Treatment of acute ICA occlusion has been reviewed previously by Meyer et al.151 Although most of the patients in this review failed to demonstrate good neurological recovery initially after emergency CEA, nine patients (26.5%) had a normal neurological exam and four (11.8%) had a minimal deficit at follow-up evaluation. Although this series reported a mortality rate of 21%, a mortality rate of 42% was reported in a joint study involving a series of 50 patients who underwent CEA for acute carotid occlusion.

Endovascular therapy is an emerging technique for the treatment of symptomatic, acute occlusion of the ICA (rates of recanalization and hemorrhage are discussed elsewhere in this chapter). Uno et al. have described promising results with the use of a combination of surgical and endovascular techniques to recanalize acutely occluded carotid arteries. The Buffalo group has used microcatheter techniques for opening acute carotid occlusions. Following identification of the occlusion by diagnostic angiography, IA thrombolytics (such as reteplase) may be given. If this fails to completely recanalize the vessel, a microwire may be used to cross the occlusion. Often, the occlusion is tenacious; and a microwire does not have enough stiffness to be navigated through the clot. In this situation, an exchange length 0.035-inch wire is used to cross the thrombotic occlusion. One must be careful, as often there is an underlying severe stenosis (caused by atherosclerosis) that led to the acute thrombotic occlusion. Contrast material should be injected liberally in an attempt to identify the parent vessel lumen distal to the occlusion once a microcatheter has successfully been negotiated distal to this occlusion. The presence of intracranial tandem embolic occlusions portends a poor prognosis for treatment of cervical carotid occlusion with CEA. However, one group reported improvement in four patients with concomitant occlusions following cervical and intracranial IA thrombolysis with urokinase infusion and mechanical clot disruption.39 More thrombolytic agent may be infused into the thrombus if diagnostic angiography displays clot burden surrounding the catheter. Once the catheter has traversed the thrombus and is in the true lumen of the parent vessel (distal to the thrombus), mechanical thrombolysis may be used. At this point, the 0.035-inch wire is exchanged for a 0.014-inch wire, and measurements are obtained to determine the caliber of the parent vessel lumen. Unlike in the coronary circulation, one should not liberally over size the balloons used in carotid revascularization. Techniques used to revascularize acutely occluded cervical carotid arteries include stent-assisted angioplasty of the carotid artery or angioplasty alone in the region of the thrombus.

Once the cervical carotid artery has been successfully opened, careful superselective angiography of the intracranial vasculature, ipsilateral to the lesion, must be completed. Full attention must be paid to the second- and third-order branches of the middle cerebral and anterior cerebral arteries, as branch occlusions may have resulted from distal vessel embolization. As most of these patients are treated after the induction of general anesthesia, careful evaluation of the angiographic images is crucial to appreciate subtle occlusion resulting from cervical carotid emboli.

Recent Advances

Recently the Buffalo group has reported the use of proximal occlusion guide catheters to arrest proximal flow in the common carotid artery. Additionally, balloons are placed in the distal ICA and ECA to arrest flow temporarily while navigating stent devices accross the occlusion. This minimizes embolic risk. Once the stent is placed and the vessel is open, the ECA balloon is deflated to "wash out " any debris that may have been released during stenting. The CCA guiding catheter balloon is also deflated and finally the ICA balloon is deflated last. This technique serves like an "internal cross clamping" technique seen in carotid surgery. More work is needed to understand the merits of this technique and the utility of opening acture carotid symptomatic occlusions.

Permission

Reprinted with permission from Mohr JP, Choi DW, Grotta JC, Weir B, Wolf PA (eds): STROKE: PATHOPHYSIOLOGY, DIAGNOSIS, AND MANAGEMENT (4th edition), pp. 1475-1520 (chapter 78), Copyright Elsevier 2004. Permission has been granted to reproduce this material in online electronic format for non-exclusive world English rights.

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