Case Report Acute Internal Carotid Artery Occlusion Long after Carotid Revascularization by Vein Graft Ryota Tamura, MD,*,‡ Nobuyuki Ohara, MD,* Yasutaka Murakami, MD,* Hirotoshi Imamura, MD, PhD,† Nobuyuki Sakai, MD, PhD,† and Nobuo Kohara, MD, PhD* We report the case of a 27-year-old woman with acute internal carotid artery occlusion long after carotid artery revascularization by vein graft. She presented with sudden unconsciousness and left hemiparesis. Her right carotid artery was revascularized with an ipsilateral internal jugular vein graft during a carotid body tumor resection 10 years ago. Computed tomography angiography revealed a right internal carotid artery terminus occlusion. Intravenous rt-PA and mechanical thrombectomy were performed, resulting in successful recanalization. Her neurological symptoms gradually recovered. When examining the embolic source, carotid ultrasonography for the vein graft showed intimal thickening, some high-echoic plaques, and lumen dilation, but no thrombus was observed. Color Doppler imaging showed laminar flow at the graft. Angiography after thrombectomy also showed pooling of contrast at the vein graft. We suspected that the blood flow stagnation at the vein graft induced thrombus formation; therefore, anticoagulation therapy was initiated. One year later, she was independent without recurrence of stroke, and anticoagulation therapy was replaced with aspirin because she went abroad. However, a carotid ultrasonography exam the following year revealed a huge thrombus at the graft. Anticoagulation therapy was resumed; subsequently, the thrombus decreased. In conclusion, we could monitor the long-term change in the vein graft by ultrasonography. Moreover, anticoagulation therapy was more effective. Key Words: Acute internal carotid artery occlusion—Carotid artery revascularization—Vein graft—Blood flow stagnation—Hemodynamic—Carotid ultrasonography © 2020 Elsevier Inc. All rights reserved. Introduction A 27-year-old woman presented with sudden altered level of consciousness and left hemiparesis. Her right carotid artery was revascularized with an ipsilateral internal jugular From the *Department of Neurology, Kobe City Medical Center General Hospital, Kobe, Japan; †Department of Neurosurgery, Kobe City Medical Center General Hospital, Kobe, Japan; and ‡Department of Neurology, Shiga University of Medical Science, Otsu, Japan. Received May 27, 2020; revision received September 5, 2020; accepted October 4, 2020. Corresponding author. E-mail: nobuyuki.ohara@gmail.com. 1052-3057/$ - see front matter © 2020 Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.jstrokecerebrovasdis.2020.105391 vein graft during a carotid body tumor resection 10 years ago. She was receiving aspirin for 3 years. Magnetic resonance angiography performed in 3 years after the original surgery showed no occlusion or stenosis of the graft. Further, she received no medication and medical examination until the admission. Computed tomography (CT) showed some early ischemic changes in the right hemisphere, and CT angiography revealed a right internal carotid artery terminus occlusion. Intravenous rt-PA and mechanical thrombectomy by stent retriever were performed, thereby, resulting in successful recanalization after 121 minutes from onset. One month later, her neurological symptoms recovered to a modified Rankin scale of 2. Examination for the embolic source did not show cardiogenic and blood Journal of Stroke and Cerebrovascular Diseases, Vol. 29, No. 12 (December), 2020: 105391 1 2 R. TAMURA ET AL. Figure 1. (A) Color Doppler imaging showing laminar flow at the vein graft. (B) Ultrasonography of the right carotid artery on admission showing an intimal thickening, some high-echoic plaques, and lumen dilation at the vein graft. (C E) Sequential alternating frames (1 s apart) of the angiogram showing pooling of contrast until the venous phase at the vein graft (arrowhead). (F) Ultrasonography of the vein graft showing thrombus (arrowheads) 1 year later after changing therapy from warfarin to aspirin. (G) Ultrasonography after treatment of heparin for 7 days showing a reduction of the thrombus (arrowheads). coagulopathy including antiphospholipid or anti-neutrophil cytoplasmic antibody. The possibility of hypercoagulability related to malignancy was low due to no carotid body tumor recurrence and the normal ranges of the D-dimer level. Color Doppler imaging showed laminar flow at the graft (Fig. 1A). Carotid ultrasonography for the vein graft showed intimal thickening, some high-echoic plaques, and lumen dilation, but no thrombus was observed (Fig. 1B). Additionally, retrospectively comparing the maximum graft diameter by CT angiography, we found that it had dilated from 8.8 £ 7.9 mm in 21 months after the original surgery to 9.6 £ 8.9 mm on admission. These findings were consistent with the pooling of contrast at the graft observed by angiography after thrombectomy (Fig. 1C E). We suspected that the blood flow stagnation at the vein graft induced thrombus formation; therefore, we administered warfarin as a secondary preventative treatment for embolism. One year later, she had no recurrence of stroke, and warfarin was replaced with aspirin because she went abroad. However, 1 year later, carotid ultrasonography revealed a huge thrombus at the graft (Fig. 1F). Anticoagulation therapy was resumed; subsequently, the thrombus decreased after 7 days (Fig. 1G). Parent artery occlusion or reconstruction, such as a new graft insertion or covered stent placement, was also discussed with other neurologists and neurosurgeons, and we decided to treat our case with medication after considering the risk of surgery. After anticoagulation with aspirin, no thrombus recurrence occurred. To our knowledge, cases of ischemic strokes immediately or a few months after revascularization with a vein graft have been reported. However, to date, there are no reported cases of ischemic stroke several years later.1-3 In this case, we could evaluate the long-term change in the vein graft and demonstrate the etiology of thrombus formation by ultrasonography. These findings are clinically useful to obtain a better understanding of the pathological changes and prognosis of vein graft at other sites, such as the coronary and iliac arteries, which cannot be evaluated by ultrasound. Furthermore, vein grafts gradually increase in wall stiffness and lumen diameter.4 These remodeling events probably induce laminar flow and blood stagnation, which might result in the thrombus formation. In this situation, anticoagulation therapy may be better than antiplatelet therapy for maintaining vein graft patency. Although there have been no reports of investigating blood stagnation or anticoagulation therapy of the vein graft, blood stagnation similar to the angiogram of this case can occur in a case of a patient with carotid web, which is thought to induce blood stagnation, resulting in embolization. In such patients, the stroke recurrence rate is high despite performing antiplatelet therapy, and carotid stenting or carotid endarterectomy is effective.5 The efficacy of anticoagulation in these patients remains unknown due to the limited number of reports. Therefore, additional evaluation is required in these situations. In a previous report, follow-up ultrasonography of the vein graft was performed every few months at first and, then, every few times a year.6 Vein graft is mainly evaluated if stenosis or occlusion occurs, but blood stagnation and thrombus should be also evaluated. To evaluate the blood flow of a graft, ultrasonography or angiography was useful in this case, and ultrasonography may be ACUTE INTERNAL CAROTID ARTERY OCCLUSION LONG AFTER CAROTID REVASCULARIZATION preferable for long-term management. Further observation of our case would provide additional information regarding vein graft durability. Informed consent The patient has provided permission to publish details of the case, including accompanying images, and the identity of the patient has been protected. References 1. Mourad M, Saman M, Stroman D, et al. Evaluating the role of embolization and carotid artery sacrifice and reconstruction in the management of carotid body tumors. Laryngoscope 2016;126:2282-2287. 3 2. 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