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A Manual Carotid Compression Technique to Overcome Difficult Filter Protection Device Retrieval during Carotid Artery Stenting
A Manual Carotid Compression Technique to Overcome Difficult Filter Protection Device Retrieval during Carotid Artery Stenting Kouhei Nii, MD, PhD, Kanji Nakai, MD, PhD, Masanori Tsutsumi, MD, PhD, Hiroshi Aikawa, MD, PhD, Minoru Iko, MD, PhD, Kimiya Sakamoto, MD, PhD, Takafumi Mitsutake, MD, Ayumu Eto, MD, Hayatsura Hanada, MD, and Kiyoshi Kazekawa, MD, PhD
Background: We investigated the incidence of embolic protection device retrieval difficulties at carotid artery stenting (CAS) with a closed-cell stent and demonstrated the usefulness of a manual carotid compression assist technique. Methods: Between July 2010 and October 2013, we performed 156 CAS procedures using selfexpandable closed-cell stents. All procedures were performed with the aid of a filter design embolic protection device. We used FilterWire EZ in 118 procedures and SpiderFX in 38 procedures. The embolic protection device was usually retrieved by the accessory retrieval sheath after CAS. We applied a manual carotid compression technique when it was difficult to navigate the retrieval sheath through the deployed stent. We compared clinical outcomes in patients where simple retrieval was possible with patients where the manual carotid compression assisted technique was used for retrieval. Results: Among the 156 CAS procedures, we encountered 12 (7.7%) where embolic protection device retrieval was hampered at the proximal stent terminus. Our manual carotid compression technique overcame this difficulty without eliciting neurologic events, artery dissection, or stent deformity. Conclusions: In patients undergoing closed-cell stent placement, embolic protection device retrieval difficulties may be encountered at the proximal stent terminus. Manual carotid compression assisted retrieval is an easy, readily available solution to overcome these difficulties. Key Words: Carotid artery stenting—difficult retrieval—filter protection device—manual carotid compression—proximal stent terminus. Ó 2015 by National Stroke Association
Carotid artery stenting (CAS) is being evaluated as an alternative to carotid endarterectomy in high-risk patients.1 Garg et al2 and Touze et al3 reported that the
From the Department of Neurosurgery, Fukuoka University Chikushi Hospital, Chikushino, Japan. Received April 24, 2014; revision received July 17, 2014; accepted August 22, 2014. Address correspondence to Kouhei Nii, MD, PhD, Department of Neurosurgery, Fukuoka University Chikushi Hospital, 1-1-1 Zokumyoin, Chikushino, Fukuoka 818-8502, Japan. E-mail: k.nii@cis. fukuoka-u.ac.jp. 1052-3057/$ - see front matter Ó 2015 by National Stroke Association http://dx.doi.org/10.1016/j.jstrokecerebrovasdis.2014.08.022
210
incidence of stroke was lower in patients operated with than without embolic protection devices (EPDs), used to prevent embolic neurologic complications related to CAS. Standard CAS procedures are performed with the aid of distal EPDs. In Japan, a filter design device tends to be applied. The successful retrieval of EPDs is a determinant of procedural success because it is the last step in CAS. The close proximity of the EPD wire to an irregular stent or conformation of the stent to the artery can render navigation of the retrieval device through the deployed stent difficult.4-6 We investigated the incidence of EDP retrieval difficulties and demonstrated the usefulness of a manual carotid compression assist technique to aid in the retrieval of EPDs.
Journal of Stroke and Cerebrovascular Diseases, Vol. 24, No. 1 (January), 2015: pp 210-214
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Figure 1. Photographs and fluoroscopic images showing that the manual carotid compression technique changes the angle between the common carotid artery and stent. Advancement of the retrieval device is hampered by the proximal stent terminus (A, B: arrow head). The application of pressure at a site lateral or vertical to the neck straightens the stent and allows retrieval of the tight-fitting embolic protection device wire (C, D: arrow head).
Materials and Methods Between July 2010 and October 2013, we performed 156 CAS procedures with the aid of EPDs in patients with carotid atherosclerotic disease or stenosis. Indications for intervention were greater than 50% stenosis in symptomatic patients and greater than 80% stenosis in asymptomatic patients. For at least 3 days before CAS, all patients underwent oral antiplatelet treatment consisting of aspirin (100 mg daily) and clopidogrel (75 mg daily), or of cilostazol (200 mg daily). All patients received heparin during the procedure to maintain an activated clotting time of more than
300 seconds under general anesthesia. They underwent standard CAS including the placement of filter design EPDs, predilation angioplasty, placement of a selfexpandable closed-cell stent, and postdilation angioplasty if necessary (residual stenosis .20%). Filter design EPDs were used to treat all lesions. We used FilterWire EZ (Boston Scientific, Natick, MA) to treat 118 lesions. After the approval of the SpiderFX (eV3 Neurovascular, Irvine, CA), we used it to address the next 38 lesions. A Carotid WALLSTENT (Boston Scientific) was placed in all patients. After the CAS procedure, the EPDs were retrieved using the accessory retrieval sheath. When we encountered difficulties in navigating the retrieval sheath
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Figure 2. Fluoroscopic images showing the geometric change between the common carotid artery and the stent produced by the manual carotid compression technique. The advance of the accessory retrieval sheath is hampered by the proximal stent terminus (A: arrow head). Under manual carotid compression the accessory retrieval sheath is easily navigated through the stent (B: arrow).
through the deployed stent, we applied a manual carotid compression technique. By applying gentle lateral or vertical pressure at a site below the proximal stent edge, we were able to straighten the stent. This made it possible to remove tight-fitting EPDs under biplane fluoroscopy. The retrieval sheath was then navigated through the stent (Fig 1). After CAS, we monitored vital and neurologic signs. All patients underwent diffusion-weighted magnetic resonance imaging before and within 5 days after the procedure to check for new microembolic lesions. Difficult EPD retrieval was recorded when the manual carotid compression technique was required for navigation of the retrieval sheath through the deployed stent. Neurologic events were categorized as transient ischemic attacks (neurologic deficit lasting ,24 hours), minor stroke (neurologic deficit lasting .24 hours with a National Institutes of Health Stroke Scale score , 4), and major stroke (neurologic deficit lasting .24 hours, National Institutes of Health Stroke Scale score .4). We compared the clinical outcomes in patients with simple and difficult EPD retrieval. The Fisher exact test was used for categorical variables. A P value less than .05 was considered statistically significant.
Illustrative Case This 73-year-old woman presented with left hemiparesis due to cerebral infarction. Angiography revealed 70% right internal carotid artery (ICA) stenosis by North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria.7 Because she had a past medical
history of coronary artery disease, we considered her eligible for CAS. Using an 8-F guiding catheter (Guider Softip; Boston Scientific) we inserted a FilterWire EZ into the distal ICA. Based on the vessel diameter, the stenosis was predilated with a 4-mm balloon (Symmetry; Boston Scientific). Then a Carotid WALLSTENT (fully open: diameter 5 10 mm, length 5 24 mm) was placed; the stent was sized based on our estimation of the normal ICA diameter. We retrieved the FilterWire EZ after stent placement but were unable to pass the accessory retrieval sheath through the proximal terminus of the stent. Manual carotid compression separated the tight EPD wire from the stent under biplane fluoroscopy, and the retrieval sheath was navigated through the deployed stent (Fig 2). Angiograms obtained after retrieval of the FilterWire EZ device revealed no distal embolism and no ICA stenosis.
Results Table 1 lists the patient characteristics and outcomes. We encountered difficulties in FilterWire EZ removal in 12 of the 118 CAS procedures (10.2%); all were addressed successfully by manual carotid compression. We experienced no difficulties retrieving the EPD when we used the SpiderFX device (P 5 .04). No patients manifested carotid artery dissection or stent deformation immediately after CAS. Neurologic events occurred after 8 of 156 procedures (5.1%); there were 3 transient ischemic attacks (1.9%), 4 minor strokes (2.6%), and 1 major stroke (.6%). All events occurred after CAS in which simple retrieval was possible (P . .5).
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Table 1. Baseline characteristics and clinical outcomes in patients with simple and difficult EPD retrieval
Characteristic
All patients, N 5 156
Difficult retrieval, N 5 12
Simple retrieval, N 5 144
P value
EPD, n (%) FilterWire EZ SpiderFX Neurologic events, n (%) TIA Minor stroke Major stroke Microembolism on postprocedural DW-MRI, n (%)
118 (75.6) 38 (24.4) 8 (5.1) 3 (1.9) 4 (2.6) 1 (.6) 46 (29.5)
12 0 0 0 0 0 3 (25%)
106 38 8 (5.6) 3 (2.1) 4 (2.8) 1 (.7) 43 (29.9)
.04* .04* ..5* ..5* ..5* ..5* ..5*
Abbreviations: DW-MRI, diffusion-weighted magnetic resonance imaging; EPD, embolic protection device; TIA, transient ischemic attack. n indicates number of procedures. *By the Fisher exact test.
Diffusion-weighted magnetic resonance imaging detected new microembolic lesions after 46 of 156 (29.5%) CAS procedures; 5 of 46 (10.9%) microembolic lesions were symptomatic. We observed microembolism after 3 of 12 (25%) difficult and 43 of 144 (29.9%) simple retrievals; the difference was not statistically significant (P . .5).
Discussion Lian et al8 reported no difficulties in retrieving EPDs after closed-cell stent placement. In our series, the incidence of EPD retrieval difficulty was 7.7% (12 of 156), and all difficulties were encountered at the proximal stent terminus. On the other hand, in patients treated by open-cell stent placement, difficulties with EPD retrieval tend to occur in-stent. In the presence of calcified plaques or tortuous carotid lesions, the struts of the open-cell stent protrude into the stent, and this can hamper inserting or advancing the retrieval device.6,8 In contrast, when closed-cell stents are used, the retrieval device can be advanced without interference from the stent struts because the adjacent ring segments are connected at every possible junction with flexible bridge connectors.9 However, we think that the difficulties occurred at the proximal stent terminus because the straight closed-cell stents are of low flexibility and low conformability to the vessel.10 EPD retrieval is the last step in the CAS procedure; retrieval failure equals treatment failure. Others overcame EPD retrieval difficulties surgically.11,12 Daugherty et al4 reported the usefulness of a vertebral catheter when retrieval of a distal filter protection device was unsuccessful. However, the surgical approach may elicit additional complications because it adds operative time, and coaxial catheter techniques require more steps and may increase the risk for thromboembolism and stent fracture. Malik et al5 suggested another simple retrieval technique consisting of neck turning and swallowing, a method not possible in patients operated under general
anesthesia. Watanabe et al6 used manual external carotid artery manipulation in patients undergoing open-cell stent CAS. This technique can be applied when retrieval difficulties occur at the proximal stent terminus; it does not affect the outward radial stent force because the compression site on the common carotid artery is lower than at the proximal stent terminus. Biplane fluoroscopy confirmed that their method involved minimum motion. We encountered no retrieval difficulties with the SpiderFX device. A feature of these EPDs is independent wire movement that keeps the EPD in place during procedural manipulations and allows for longitudinal and rotational filter movement. This facilitates separation of a tight-fitting EPD wire from the stent edge during EPD retrieval and is unlikely to create retrieval difficulties. Our study has some limitations. All our patients underwent CAS with a closed-cell stent, and the number of patients treated with the SpiderFX device was relatively small. We are in the process of carrying out studies in larger cohorts to determine whether different filter device types affect the development of retrieval difficulties. In conclusion, our manual carotid compression assist technique was an easy solution to EPD retrieval difficulties that tended to develop at the proximal stent terminus in patients undergoing CAS with closed-cell stents.
References 1. Yadav JS, Wholey MH, Kuntz RE, et al. Protected carotidartery stenting versus endarterectomy in high-risk patients. N Engl J Med 2004;351:1493-1501. 2. Garg N, Karagiorgos N, Pisimisis GT, et al. Cerebral protection devices reduce periprocedural strokes during carotid angioplasty and stenting: a systematic review of the current literature. J Endovasc Ther 2009;16:412-427. 3. Touze E, Trinquart L, Chatellier G, et al. Systematic review of the perioperative risks of stroke or death after carotid angioplasty and stenting. Stroke 2009; 40:e683-e693. 4. Daugherty WP, White JB, Cloft HJ, et al. Rescue retrieval of AngioGuard embolic capture system after failure of
K. NII ET AL.
214
5.
6.
7.
8.
capture sheath retrieval in carotid angioplasty and stenting. AJNR Am J Neuroradiol 2008;29:1594-1595. Malik RK, Vouyouka A, Salloum A, et al. Tips and techniques in carotid artery stenting. J Vasc Surg 2009; 50:216-220. Watanabe M, Kai Y, Hirano T, et al. Manual external carotid artery manipulation for failed device advance through the stent in carotid artery stent placement. A technical note. J Vasc Interv Neurol 2013;6:52-55. 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;325:445-453. Lian X, Liu W, Li M, et al. Risk factors and complications associated with difficult retrieval of embolic protection
9.
10.
11.
12.
devices in carotid artery stenting. Cardiovasc Intervent Radiol 2012;35:43-48. Tsutsumi M, Aikawa H, Onizuka M, et al. Carotid artery stenting for calcified lesions. AJNR Am J Neuroradiol 2008;29:1590-1593. M€ uller-H€ ulsbeck S, Sch€ afer PJ, Charalambous N, et al. Comparison of carotid stents: an in-vitro experiment focusing on stent design. J Endovasc Ther 2009;16:168-177. Cremonesi A, Manetti R, Setacci F, et al. Protected carotid stenting: clinical advantages and complications of embolic protection devices in 442 consecutive patients. Stroke 2003;34:1936-1941. Shilling K, Uretsky BF, Hunter GC. Entrapment of a cerebral embolic protection device–a case report. Vasc Endovascular Surg 2006;40:229-233.
Background: We investigated the incidence of embolic protection device retrieval difficulties at carotid artery stenting (CAS) with a closed-cell stent and demonstrated the usefulness of a manual carotid compression assist technique. Methods: Between July 2010 and October 2013, we performed 156 CAS procedures using selfexpandable closed-cell stents. All procedures were performed with the aid of a filter design embolic protection device. We used FilterWire EZ in 118 procedures and SpiderFX in 38 procedures. The embolic protection device was usually retrieved by the accessory retrieval sheath after CAS. We applied a manual carotid compression technique when it was difficult to navigate the retrieval sheath through the deployed stent. We compared clinical outcomes in patients where simple retrieval was possible with patients where the manual carotid compression assisted technique was used for retrieval. Results: Among the 156 CAS procedures, we encountered 12 (7.7%) where embolic protection device retrieval was hampered at the proximal stent terminus. Our manual carotid compression technique overcame this difficulty without eliciting neurologic events, artery dissection, or stent deformity. Conclusions: In patients undergoing closed-cell stent placement, embolic protection device retrieval difficulties may be encountered at the proximal stent terminus. Manual carotid compression assisted retrieval is an easy, readily available solution to overcome these difficulties. Key Words: Carotid artery stenting—difficult retrieval—filter protection device—manual carotid compression—proximal stent terminus. Ó 2015 by National Stroke Association
Carotid artery stenting (CAS) is being evaluated as an alternative to carotid endarterectomy in high-risk patients.1 Garg et al2 and Touze et al3 reported that the
From the Department of Neurosurgery, Fukuoka University Chikushi Hospital, Chikushino, Japan. Received April 24, 2014; revision received July 17, 2014; accepted August 22, 2014. Address correspondence to Kouhei Nii, MD, PhD, Department of Neurosurgery, Fukuoka University Chikushi Hospital, 1-1-1 Zokumyoin, Chikushino, Fukuoka 818-8502, Japan. E-mail: k.nii@cis. fukuoka-u.ac.jp. 1052-3057/$ - see front matter Ó 2015 by National Stroke Association http://dx.doi.org/10.1016/j.jstrokecerebrovasdis.2014.08.022
210
incidence of stroke was lower in patients operated with than without embolic protection devices (EPDs), used to prevent embolic neurologic complications related to CAS. Standard CAS procedures are performed with the aid of distal EPDs. In Japan, a filter design device tends to be applied. The successful retrieval of EPDs is a determinant of procedural success because it is the last step in CAS. The close proximity of the EPD wire to an irregular stent or conformation of the stent to the artery can render navigation of the retrieval device through the deployed stent difficult.4-6 We investigated the incidence of EDP retrieval difficulties and demonstrated the usefulness of a manual carotid compression assist technique to aid in the retrieval of EPDs.
Journal of Stroke and Cerebrovascular Diseases, Vol. 24, No. 1 (January), 2015: pp 210-214
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Figure 1. Photographs and fluoroscopic images showing that the manual carotid compression technique changes the angle between the common carotid artery and stent. Advancement of the retrieval device is hampered by the proximal stent terminus (A, B: arrow head). The application of pressure at a site lateral or vertical to the neck straightens the stent and allows retrieval of the tight-fitting embolic protection device wire (C, D: arrow head).
Materials and Methods Between July 2010 and October 2013, we performed 156 CAS procedures with the aid of EPDs in patients with carotid atherosclerotic disease or stenosis. Indications for intervention were greater than 50% stenosis in symptomatic patients and greater than 80% stenosis in asymptomatic patients. For at least 3 days before CAS, all patients underwent oral antiplatelet treatment consisting of aspirin (100 mg daily) and clopidogrel (75 mg daily), or of cilostazol (200 mg daily). All patients received heparin during the procedure to maintain an activated clotting time of more than
300 seconds under general anesthesia. They underwent standard CAS including the placement of filter design EPDs, predilation angioplasty, placement of a selfexpandable closed-cell stent, and postdilation angioplasty if necessary (residual stenosis .20%). Filter design EPDs were used to treat all lesions. We used FilterWire EZ (Boston Scientific, Natick, MA) to treat 118 lesions. After the approval of the SpiderFX (eV3 Neurovascular, Irvine, CA), we used it to address the next 38 lesions. A Carotid WALLSTENT (Boston Scientific) was placed in all patients. After the CAS procedure, the EPDs were retrieved using the accessory retrieval sheath. When we encountered difficulties in navigating the retrieval sheath
K. NII ET AL.
212
Figure 2. Fluoroscopic images showing the geometric change between the common carotid artery and the stent produced by the manual carotid compression technique. The advance of the accessory retrieval sheath is hampered by the proximal stent terminus (A: arrow head). Under manual carotid compression the accessory retrieval sheath is easily navigated through the stent (B: arrow).
through the deployed stent, we applied a manual carotid compression technique. By applying gentle lateral or vertical pressure at a site below the proximal stent edge, we were able to straighten the stent. This made it possible to remove tight-fitting EPDs under biplane fluoroscopy. The retrieval sheath was then navigated through the stent (Fig 1). After CAS, we monitored vital and neurologic signs. All patients underwent diffusion-weighted magnetic resonance imaging before and within 5 days after the procedure to check for new microembolic lesions. Difficult EPD retrieval was recorded when the manual carotid compression technique was required for navigation of the retrieval sheath through the deployed stent. Neurologic events were categorized as transient ischemic attacks (neurologic deficit lasting ,24 hours), minor stroke (neurologic deficit lasting .24 hours with a National Institutes of Health Stroke Scale score , 4), and major stroke (neurologic deficit lasting .24 hours, National Institutes of Health Stroke Scale score .4). We compared the clinical outcomes in patients with simple and difficult EPD retrieval. The Fisher exact test was used for categorical variables. A P value less than .05 was considered statistically significant.
Illustrative Case This 73-year-old woman presented with left hemiparesis due to cerebral infarction. Angiography revealed 70% right internal carotid artery (ICA) stenosis by North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria.7 Because she had a past medical
history of coronary artery disease, we considered her eligible for CAS. Using an 8-F guiding catheter (Guider Softip; Boston Scientific) we inserted a FilterWire EZ into the distal ICA. Based on the vessel diameter, the stenosis was predilated with a 4-mm balloon (Symmetry; Boston Scientific). Then a Carotid WALLSTENT (fully open: diameter 5 10 mm, length 5 24 mm) was placed; the stent was sized based on our estimation of the normal ICA diameter. We retrieved the FilterWire EZ after stent placement but were unable to pass the accessory retrieval sheath through the proximal terminus of the stent. Manual carotid compression separated the tight EPD wire from the stent under biplane fluoroscopy, and the retrieval sheath was navigated through the deployed stent (Fig 2). Angiograms obtained after retrieval of the FilterWire EZ device revealed no distal embolism and no ICA stenosis.
Results Table 1 lists the patient characteristics and outcomes. We encountered difficulties in FilterWire EZ removal in 12 of the 118 CAS procedures (10.2%); all were addressed successfully by manual carotid compression. We experienced no difficulties retrieving the EPD when we used the SpiderFX device (P 5 .04). No patients manifested carotid artery dissection or stent deformation immediately after CAS. Neurologic events occurred after 8 of 156 procedures (5.1%); there were 3 transient ischemic attacks (1.9%), 4 minor strokes (2.6%), and 1 major stroke (.6%). All events occurred after CAS in which simple retrieval was possible (P . .5).
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Table 1. Baseline characteristics and clinical outcomes in patients with simple and difficult EPD retrieval
Characteristic
All patients, N 5 156
Difficult retrieval, N 5 12
Simple retrieval, N 5 144
P value
EPD, n (%) FilterWire EZ SpiderFX Neurologic events, n (%) TIA Minor stroke Major stroke Microembolism on postprocedural DW-MRI, n (%)
118 (75.6) 38 (24.4) 8 (5.1) 3 (1.9) 4 (2.6) 1 (.6) 46 (29.5)
12 0 0 0 0 0 3 (25%)
106 38 8 (5.6) 3 (2.1) 4 (2.8) 1 (.7) 43 (29.9)
.04* .04* ..5* ..5* ..5* ..5* ..5*
Abbreviations: DW-MRI, diffusion-weighted magnetic resonance imaging; EPD, embolic protection device; TIA, transient ischemic attack. n indicates number of procedures. *By the Fisher exact test.
Diffusion-weighted magnetic resonance imaging detected new microembolic lesions after 46 of 156 (29.5%) CAS procedures; 5 of 46 (10.9%) microembolic lesions were symptomatic. We observed microembolism after 3 of 12 (25%) difficult and 43 of 144 (29.9%) simple retrievals; the difference was not statistically significant (P . .5).
Discussion Lian et al8 reported no difficulties in retrieving EPDs after closed-cell stent placement. In our series, the incidence of EPD retrieval difficulty was 7.7% (12 of 156), and all difficulties were encountered at the proximal stent terminus. On the other hand, in patients treated by open-cell stent placement, difficulties with EPD retrieval tend to occur in-stent. In the presence of calcified plaques or tortuous carotid lesions, the struts of the open-cell stent protrude into the stent, and this can hamper inserting or advancing the retrieval device.6,8 In contrast, when closed-cell stents are used, the retrieval device can be advanced without interference from the stent struts because the adjacent ring segments are connected at every possible junction with flexible bridge connectors.9 However, we think that the difficulties occurred at the proximal stent terminus because the straight closed-cell stents are of low flexibility and low conformability to the vessel.10 EPD retrieval is the last step in the CAS procedure; retrieval failure equals treatment failure. Others overcame EPD retrieval difficulties surgically.11,12 Daugherty et al4 reported the usefulness of a vertebral catheter when retrieval of a distal filter protection device was unsuccessful. However, the surgical approach may elicit additional complications because it adds operative time, and coaxial catheter techniques require more steps and may increase the risk for thromboembolism and stent fracture. Malik et al5 suggested another simple retrieval technique consisting of neck turning and swallowing, a method not possible in patients operated under general
anesthesia. Watanabe et al6 used manual external carotid artery manipulation in patients undergoing open-cell stent CAS. This technique can be applied when retrieval difficulties occur at the proximal stent terminus; it does not affect the outward radial stent force because the compression site on the common carotid artery is lower than at the proximal stent terminus. Biplane fluoroscopy confirmed that their method involved minimum motion. We encountered no retrieval difficulties with the SpiderFX device. A feature of these EPDs is independent wire movement that keeps the EPD in place during procedural manipulations and allows for longitudinal and rotational filter movement. This facilitates separation of a tight-fitting EPD wire from the stent edge during EPD retrieval and is unlikely to create retrieval difficulties. Our study has some limitations. All our patients underwent CAS with a closed-cell stent, and the number of patients treated with the SpiderFX device was relatively small. We are in the process of carrying out studies in larger cohorts to determine whether different filter device types affect the development of retrieval difficulties. In conclusion, our manual carotid compression assist technique was an easy solution to EPD retrieval difficulties that tended to develop at the proximal stent terminus in patients undergoing CAS with closed-cell stents.
References 1. Yadav JS, Wholey MH, Kuntz RE, et al. Protected carotidartery stenting versus endarterectomy in high-risk patients. N Engl J Med 2004;351:1493-1501. 2. Garg N, Karagiorgos N, Pisimisis GT, et al. Cerebral protection devices reduce periprocedural strokes during carotid angioplasty and stenting: a systematic review of the current literature. J Endovasc Ther 2009;16:412-427. 3. Touze E, Trinquart L, Chatellier G, et al. Systematic review of the perioperative risks of stroke or death after carotid angioplasty and stenting. Stroke 2009; 40:e683-e693. 4. Daugherty WP, White JB, Cloft HJ, et al. Rescue retrieval of AngioGuard embolic capture system after failure of
K. NII ET AL.
214
5.
6.
7.
8.
capture sheath retrieval in carotid angioplasty and stenting. AJNR Am J Neuroradiol 2008;29:1594-1595. Malik RK, Vouyouka A, Salloum A, et al. Tips and techniques in carotid artery stenting. J Vasc Surg 2009; 50:216-220. Watanabe M, Kai Y, Hirano T, et al. Manual external carotid artery manipulation for failed device advance through the stent in carotid artery stent placement. A technical note. J Vasc Interv Neurol 2013;6:52-55. 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;325:445-453. Lian X, Liu W, Li M, et al. Risk factors and complications associated with difficult retrieval of embolic protection
9.
10.
11.
12.
devices in carotid artery stenting. Cardiovasc Intervent Radiol 2012;35:43-48. Tsutsumi M, Aikawa H, Onizuka M, et al. Carotid artery stenting for calcified lesions. AJNR Am J Neuroradiol 2008;29:1590-1593. M€ uller-H€ ulsbeck S, Sch€ afer PJ, Charalambous N, et al. Comparison of carotid stents: an in-vitro experiment focusing on stent design. J Endovasc Ther 2009;16:168-177. Cremonesi A, Manetti R, Setacci F, et al. Protected carotid stenting: clinical advantages and complications of embolic protection devices in 442 consecutive patients. Stroke 2003;34:1936-1941. Shilling K, Uretsky BF, Hunter GC. Entrapment of a cerebral embolic protection device–a case report. Vasc Endovascular Surg 2006;40:229-233.