Introduction

Complications associated with carotid artery angioplasty and stenting (CAS) may occur during or after the procedure and generally present as neurological symptoms due to an embolism or thrombus.4) Physicians can prevent these complications by using protective filters.11) Cerebral infarction is a well-known CAS complication. However, without intracranial infarction, central retinal artery occlusion (CRAO) after CAS is not a common complication.

Case Report

An 80-year-old man, who complained of left side weakness and slurred speech, was admitted to the hospital. He had been diagnosed with and treated for hypertension for 10 years. Diffusion weighted magnetic resonance imaging (DW-MRI) showed a high signal lesion on his right centrum ovale, and a neck magnetic resonance angiogram (MRA) showed a right proximal carotid artery stenosis (Fig. 1). Single-photon emission computed tomography (SPECT) showed a decreasing perfusion in right fronto-parietal lobe under the non-acetazolamide challenge. Conventional angiography showed severe stenosis in the proximal part of right internal carotid artery (ICA). Normal ICA diameter was 4.52 mm. However, stenotic lesion was 1.78 mm. According to the North American Symptomatic Carotid Endarterectomy Trial (NASCET), 60% stenosis was shown (Fig. 2).

The patient underwent carotid angioplasty and CAS twenty days after ischemic attack, receiving an antiplatelet agent for one week. After inserting an 8Fr sheath via right femoral puncture, the physician used an exchange technique to place an 8Fr guiding catheter (Mach 1, Boston Scientific, Fremont, CA, USA) in the patient's right common carotid artery and placed an embolic protection device (FilterWire EZTM 190 cm, Boston Scientific) in the petrous portion of the internal carotid artery (ICA), followed by a balloon catheter (Ultrasoft SV 4.0/2.0 cm, Boston Scientific) on the stenosis lesion of the right proximal ICA. The patient underwent balloon angioplasty three times because the result of carotid angioplasty was not satisfactory in spite of two time trials (Fig. 3. A). After angioplasty, a carotid stent (Carotid Wallstent TM Monorail TM diameter 10.0 mm, length 30 mm, Boston Scientific) was applied, from the ICA to the common carotid artery, which effectively covered the ICA stenosis

lesion (Fig. 3. B). There was no further balloon angioplasty after applying the stent.

The angiography after the CAS revealed increasing intracranial cerebral flow and no significant abnormal findings (Fig. 4). However, the patient complained of blurred vision in his right eye three hours after the CAS and of blindness in the right eye 12 hours after CAS. DW MRI was shown no significant findings in the cerebrum (Fig.5). Right eye fundus photography revealed a cherry-red spot on the macula, the retina's white ground-glass appearance and attenuated arterioles (Fig. 6. A). A fluorescein angiogram (FAG) of the right eye showed delayed filling of the superior temporal and inferior nasal arteries, and a filling defect of the inferior temporal artery (Fig. 6. B). After five days, Patient’s visual acuity was improved to 0.02 on the standard Korean eye chart(logarithm of the minimum angle of resolution scale) and a follow-up FAG revealed recovery of the filling defect of the central retinal artery (Fig. 7). After one month, fundus photography showed resolution of the retina edema and generalized arterial attenuation (Fig. 8).

Discussion

CAS can be a preferred treatment method for certain patients who are not good candidates for carotid endarterectomy, such as patients who experienced recurrent stenosis after a previous endarterectomy, who have medical problems, and suffer from an anatomically inaccessible lesion above the C2 level or radiation-induced stenosis.1-3)8) Complications associated with CAS are major or minor stroke, TIA, seizure, bradycardia, vasospasm, dissection and hypotension.10)11)14)

Embolic protection devices are useful for preventing CAS-induced thromboembolic infarctions, but several studies showed this is not a perfect solution. Kim et al.7) reported detecting a new, high signal intensity lesion on DW-MRI in about 39% of their CAS procedures with protection devices, with no apparent major arterial or territorial infarctions. du Mesnil et al.6) documented that 19 of 50 cases treated with CAS, including protection devices, showed punctuated new DW MRI lesions. These lesions have been detected in vascular territories independent of the stented carotid artery.

In particular, filter-type protection devices cannot prevent the transportation of embolic particles smaller than the filter pores, and the filter retrieval process itself might cause distal embolization.7) Another possible reason of thromboembolic infarction caused by CAS is post-procedural transport of in situ embolus on the carotid stent lesion. Embolic protection device can protect acute ischemia during CAS, but stent can’t cover in situ embolus after CAS. According to the above studies, such embolic events are probably correlated with certain catheterization procedures and the placement of large-caliber guiding catheters. Regarding the etiology of CRAO, procedure like carotid angiography or intravitreal steroid injection can result

in retinal artery occlusions.12)13) Sudden and profound visual loss is a disease presentation. After a retinal infarction, the patient's prognosis is poor. Even though DW-MRI after CAS did not show a newly developed ischemic lesion on the cerebrum, CRAO may have been an embolic complication in our case. The patient had some risk factors for CRAO or ischemic stroke. He had suffered from hypertension for 10 years, had carotid artery atherosclerotic disease, and was elderly.

Therefore, we hypothesized that an embolus had obstructed the retinal artery, as the symptoms occurred just 12 hours after his CAS. Atherosclerosis of the ophthalmic artery is another possible cause of CRAO. Even though we did not find a severe ophthalmic artery stenosis on our patient's angiography, he might have suffered an atherosclerotic change in the ophthalmic artery due to hypertension, old age, or systemic atherosclerosis. In addition, a dynamic change in ICA blood flow might have influenced the atherosclerotic ophthalmic artery after the CAS. We have usually been carrying out balloon angioplasty procedure once for extra-cranial carotid stenosis. However, we performed a balloon angioplasty 3 times before applying the stent. Repeated procedure might have worsened the unstable atherosclerosis of an ICA stenotic lesion. If we had performed angioplasty just once before applying the stent, we could have reduced this complication risk. Another possible cause of CRAO is external carotid artery (ECA) to ophthalmic artery anastomosis. A number of extra-orbital branches arise from the ophthalmic artery. Such extra-orbital ophthalmic branches have extensive anastomosis with the ECA.9) This anastomosis

might have offered an embolic route from the ECA to the ophthalmic artery, and we did not use an ECA protection device in this case. In our case, it was thought that the origin of CRAO was unstable in situ embolus in the carotid stenosis caused by multiple angioplasties. If CRAO had come from ophthalmic artery, angiography would have shown atherosclerosis of ophthalmic artery. Moreover, embolus might have passed ECA route. Because if embolus had passed ICA, DW-MRI would have shown new develop lesion. Patients can undergo treatment modalities that lower intraocular pressure and enhance retinal oxygenation, such as anterior chamber paracentesis, ocular massage, systemic acetazolamide, topical timolol maleate, and 5% carbon dioxide/95% oxygen inhalation. Despite these treatments, the prognosis of retinal infraction due to CRAO is poor and retinal cloudiness can become a continuing process. Currently, physicians sometimes try intravenous or intraarterial thrombolysis treatment for CRAO. The results of thrombolysis for CRAO appear to be better than either the natural history of CRAO or conservative treatment,5) but thrombolysis as a treatment for CRAO requires further studies. Embolism due to carotid atherosclerotic disease has been described as the most common cause of CRAO. Endovascular surgeons should keep in mind the risk of permanent vision loss because of carotid CAS.

Conclusion

CRAO after CAS without intracranial infarction is a rare complication. We here report a case in an elderly patient.

REFERENCES

1) Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. North American Symptomatic Carotid Endarterectomy Trial Collaborators. N Engl J Med 325:445-53, 1991

2) Endarterectomy for asymptomatic carotid artery stenosis. Executive Committee for the Asymptomatic Carotid Atherosclerosis Study JAMA 273:1421-8, 1995

3) Endovascular versus surgical treatment in patients with carotid stenosis in the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS): a randomised trial. Lancet 357:1729-37, 2001

4) Akgul E, Aksungur EH, Korur K, Aikimbaev K, Yaliniz H. A rare complication of carotid artery stenting: displacement of marker ring causing locking of stent and incomplete stent expansion. AJNR Am J Neuroradiol 28:1403-4, 2007

5) Biousse V, Calvetti O, Bruce BB, Newman NJ. Thrombolysis for central retinal artery occlusion. J Neuroophthalmol 27:215-30, 2007

6) du Mesnil de Rochemont R, Schneider S, Yan B, Lehr A, Sitzer M, Berkefeld J. Diffusion-weighted MR imaging lesions after filter-protected stenting of high-grade symptomatic carotid artery stenoses. AJNR Am J Neuroradiol 27:1321-5, 2006

7) Kim SJ, Roh HG, Jeon P, Kim KH, Lee KH, Byun HS et al. Cerebral ischemia detected with diffusion-weighted MR imaging after protected carotid artery stenting: comparison of distal balloon and filter device. Korean J Radiol 8:276-85, 2007

8) Mathew B, Bhatia V, Francis L. Nonsurgical carotid revascularization. Cardiol Rev 13:197-9, 2005

9) Osborn AG. Internal carotid artery, in Osborn AG(ed): Diagnostic cerebral angiography, ed 2. Philadelphia: Lippincott Williams & Wilkins, 1999, pp83-104

10) Park SH, Lee CY. Contralateral cerebral infarction after stent placement in carotid artery: an unexpected complication. J Korean Neurosurg Soc 44:159-62, 2008

11) Saratzis N, Saratzis A, Melas N, Lioupis A, Lykopoulos D, Ginis G et al. Carotid artery stent placement with embolic protection:single-center experience. J Vasc Interv Radiol 18:337-42, 2007

12) Shimizu T, Kiyosawa M, Miura T, Takahshi A, Tamai M. Acute obstruction of the retinal and choroidal circulation as a complication of interventional angiography. Graefes Arch Clin Exp Ophthalmol 231: 43-47, 1993

13) Shin JH, Kim DK, Yu SY, Kwak HW. A case of central retinal artery occlusion after intravitreal triamcinolone acetonide injection for diabetic macular edema in non-proliferative diabetic retinopathy. J Korean Ophthalmol Soc 47, 667-71,2006

14) Wholey MH, Wholey MH, Jarmolowski CR, Eles G, Levy D, Buecthel J. Endovascular stents for carotid artery occlusive disease. J Endovasc Surg 4: 326-38, 1997