Introduction

Surgical revascularization of the occluded extracranial carotid artery has been established as a potential therapy in selected patients.¹ However, this procedure has not been widely applied because its intrinsic risks and the questionable benefits. Endovascular revascularization of acutely and chronically occluded femoral and coronary arteries has been performed for some time with good degree of clinical and radiological success. Application of these techniques to the extracranial carotid and vertebral arteries has lagged behind for fear of dislodging emboli. With advances in endovascular techniques, increasing experience with angioplasty and stenting of large extracranial cervical vessels, and the availability of a variety of distal protection devices, several operators have reported their results following endovascular revascularization of the acutely or even chronically occluded internal carotid artery (ICA).^2–20 In this chapter, we provide an overview of the rationale, techniques, results, and complications of endovascular revascularization of acute and chronic occlusion of the extracranial ICA.

Acute carotid occlusion

Management of patients with stroke caused by acute ICA occlusion is challenging. Medical therapy alone is associated with a high rate of permanent severe neurological disability and mortality.¹ In patients with acute stroke and ICA occlusion, early restoration of flow in the occluded ICA may prevent further worsening, improve symptoms, and reduce the risk of recurrent stroke.² Currently, the invasive treatment of patients with acute ICA occlusion is not standardized. Acute ICA occlusion responds poorly to intravenous thrombolysis alone or in combination with intra-arterial pharmacological thrombolysis with recanalization rates ranging from 10%²¹ to 50%,^22–24 and resultant mortality of 50%.^21–24 Slightly better clinical results have been reported following mechanical thrombectomy, but only a few reports are available.^25,26

Over the past decade, several authors^2,3–11,27 have reported the feasibility of endovascular revascularization of the acutely occluded internal carotid artery with angioplasty and stenting with higher rates of recanalization and clinical improvement than reported with other methods (Table 21–1).

Technique

Symptomatic acute thrombosis of the proximal ICA often occurs in concomitance with ICA bifurcation (T-lesion) or MCA occlusion. The natural history of associated proximal ICA and central distal occlusions is poor.^2,3–10,12 Acute revascularization of the proximal ICA in such cases allows catheterization and thrombolysis of the distal segment and, by increasing distal flow, improves the chances of maintaining vessel patency after successful distal thrombolysis. In addition, stenting of the occluded ICA may “trap” thrombus against the carotid wall, potentially decreasing the risk of delayed distal emboli.

In these patients we perform a rapid diagnostic angiography with a 5F catheter and assess the status of the carotid bifurcation as well as the status of external carotid collaterals by studying the angiograms in the delayed phases. Angiography of the contralateral side is helpful to assess the presence or absence of collateral vessels. In the presence of a short ICA occlusion that does not extend to the ICA bifurcation terminus, the contralateral angiogram allows for a depiction of the anatomy of the ipsilateral MCA distribution. However, symptoms are usually related to distal MCA occlusion or the occlusion extends to the carotid bifurcation terminus and this distal occlusion also demands treatment.

After a diagnosis of the ICA occlusion and assessment of the collateral circulation, the 5F catheter is exchanged for a larger guide-catheter, which is placed in the distal common carotid artery. We prefer to perform the procedure under full heparinization. However, this is often not feasible because these patients had received variable doses of intravenous thrombolytics or intra-arterial pharmacological thrombolysis for coexistent distal occlusion. In such cases, a limited bolus of 2000 to 3000 units of heparin is administered before catheterization.

We usually try to cross the occluded segment with a filter-type distal protection. Often this is not possible and a stiffer and more steerable microguidewire is required to cross the occluded segment. The occlusion is then negotiated with a 0.014-inch or 0.018-inch steerable microguidewire. In some cases, a larger guidewire (0.035 inch) may be necessary. A microcatheter is then navigated over the microguidewire across the occluded segment and an angiogram through the microcatheter distal to the occluded segment is performed to assess the status of the carotid distal to the occlusion and the intracranial circulation.

With the microguidewire as a “buddy-wire,” we try to cross the occlusion with a filter wire for distal protection. When this is possible, the protection device is landed in the distal cervical segment. A self-expandable stent is deployed in the proximal cervical carotid and poststent angiograms are obtained to confirm revascularization. Immediately after stent placement, patients are administered oral clopidrogel (300 mg) and aspirin (325 mg). Based on the findings of the post-stent angiogram further intervention is usually required. This may include thrombolysis (pharmacological or mechanical) or even further stenting of the ICA distally to the occluded segment or the proximal MCA. If a central occlusion distal to the proximal ICA occlusion exists, revascularization of the distal occlusion is critical to maximize the chance of a good functional outcome.

At the completion of the procedure, strict blood pressure control is maintained in those patients with successful recanalization (systolic pressure below 160 mm Hg in patients with acute occlusions or below 140 mm Hg when the occlusion is subacute or chronic). Clopidogrel is continued for 30 days and aspirin indefinitely. A head CT scan is routinely performed the following morning to rule out hemorrhage and to assess the extent of the infarcted area (Figure 21–1).

Figure 21–1 A 69-year-old man presented with acute right hemiparesis and aphasia. Cerebral angiography, left common carotid artery injection (A) lateral projection shows acute occlusion of the origin of the left ICA immediately distal to the bifurcation. Contralateral carotid angiography (B) shows hypoplastic A1 segment (arrow) on the right with some filling of the left distal anterior cerebral artery territory through the anterior communicating artery. A guide-catheter was placed into the distal common carotid artery. We attempted to cross the occlusion with a filter wire but this proved impossible. A 0.014 microguidewire was then advanced through the occlusion. With the microguidewire in place as a “buddy wire,” we were then able to cross the occlusion with a filter wire. C, Shows the filter protection device deployed into the distal cervical ICA (arrow) and a “buddy wire” (double arrows) in place across the occlusion as well. A self-expandable stent was then advanced across the occlusion (D). Left common carotid artery injection following stent deployment, lateral projection shows flow through the stent but evidence of distal occlusion. Microcatheter injection after stent deployment shows thrombus into the cavernous ICA and occlusion of the intracranial ICA bifurcation (E). F, After mechanical and intra-arterial thrombolysis there was partial recanalization of the ipsilateral middle cerebral artery with persistent diffuse intraluminal thrombus. Telescoping enterprise (Cordis Neurovascular, Johnson and Johnson, Camden, NJ) stents placed into the M1 segment and across the intracranial ICA bifurcation: there is re-establishment of distal flow into both the anterior cerebral and middle cerebral arteries (G and H). Final lateral projection (I) shows re-establishment of flow through the previously occluded proximal ICA.

Results and Complications

Over the past 10 years, several authors have detailed their results with revascularization of the acutely occluded ICA. Nedeltchev and coworkers¹¹ studied 56 consecutive patients who suffered an MCA stroke following ICA occlusion between 1997 and 2003. Twenty-five of these patients underwent attempted endovascular revascularization (endovascular group), while 31 patients received medical treatment consisting of antiplatelet medications and, in some cases, heparin therapy (medical group). Recanalization of the ICA was achieved in 84% of patients in the endovascular group with a combination of thrombo-aspiration through an 8-French guide-catheter and stent deployment in the occluded ICA. Recanalization of the coexistent MCA occlusion (TIMI grade 2 and 3) was obtained in 52% of these patients. In the endovascular group, outcome at 3 months was favorable (modified Rankin score of 0–2) in 56% of patients and unfavorable in 24%. Twenty percent of patients died. In the medically treated group, a favorable outcome was observed in only 26% of patients. This series stresses the importance of recanalization of the coexistent distal occlusion since MCA recanalization was the only predictor of good outcome. Symptomatic hemorrhage occurred in 8%. Although concerns exist regarding the risk of dissection and vessel perforation during blind “probing” of the occluded segment, these complications were not observed in this series.

Jovin and collaborators²

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