576337
research-article2015
JETXXX10.1177/1526602815576337Journal of Endovascular TherapyHopf-Jensen et al
Clinical Investigation
Initial Clinical Experience With the Micromesh Roadsaver Carotid Artery Stent for the Treatment of Patients With Symptomatic Carotid Artery Disease
Journal of Endovascular Therapy 2015, Vol. 22(2) 220–225 © The Author(s) 2015 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1526602815576337 www.jevt.org
Silke Hopf-Jensen, MD1, Leonardo Marques, MD1, Michael Preiß, MD1, and Stefan Müller-Hülsbeck, MD, EBIR, PhD1
Abstract Purpose: To assess the effectiveness, technical aspects, handling, and safety of the micromesh Roadsaver Carotid Artery Stent in the treatment of atherosclerotic carotid artery stenosis and tandem lesions in ischemic stroke patients. Methods: Seven patients (5 men; mean age 75±11.4 years, range 53–86) suffering from symptomatic internal carotid artery (ICA) stenosis (mean 76% diameter reduction) were treated with the dual layer closed-cell stent without embolic protection. Postdilation was performed in 6 of 7 patients. Two patients were treated in the context of ischemic stroke and concurrent middle cerebral artery occlusion. Mean National Institutes of Health Stroke Scale score at admission was 12.8±5. Results: All devices were deployed satisfactorily. One wall-adherent thromboembolus in a proximal ICA was covered with the Roadsaver stent in a tandem lesion setting. The modified Rankin Scale (mRS) declined from 3.7±0.7 to 2.4±0.8 in hospital, showing an improvement in clinical symptoms. No complications were detected during or after the procedure. The 30-day mRS was 1.7±1.1. At 6 months, ultrasound examination demonstrated patency of stents and the external carotid arteries. Conclusion: The Roadsaver double layer micromesh stent seems to be safe and effective in the treatment of extracranial ICA stenosis and in the context of tandem lesions in ischemic stroke. Further studies with larger populations are warranted. Keywords carotid artery disease, carotid artery stent, internal carotid artery, stenosis, stroke, tandem lesion, closed-cell stent, opencell stent, nitinol mesh, dual layer stent
Introduction The complication rates of carotid artery stenting (CAS) have continuously decreased over recent years due to technical improvements, operator experience, a lesion-tailored interventional strategy,1 better patient selection, and improved stent design. Stent design can be classified into either open or closedcell configurations2,3 or a hybrid-cell configuration based on the density of the struts. Different materials (nitinol or cobalt–chromium) and shapes (tapered vs. straight) of carotid artery stents provide a range of geometries and mechanical properties.3 Characteristics such as high flexibility are needed to preserve vessel contours, and radial force, wall apposition, and plaque coverage are required to prevent late embolic release. Despite the variety of available carotid artery stents, there remains the desire to develop and improve the materials and designs in order to achieve sustained, permanent embolic protection.
Our aim is to demonstrate the effectiveness, technical aspects, handling, and safety of the micromesh Roadsaver Carotid Artery Stent (Terumo, Tokyo, Japan) in the treatment of extracranial carotid artery disease.
Methods Patient Population Seven patients (5 men; mean age 75±11.4 years, range 53–86) with underlying internal carotid artery (ICA) 1
Department of Diagnostic and Interventional Radiology and Neuroradiology, Diakonissenhospital Flensburg, Germany Corresponding Author: Silke Hopf-Jensen, Department of Diagnostic and Interventional Radiology/Neuroradiology, Diakonissenhosptal Flensburg, Knuthstraße 1, 24939 Flensburg, Germany. Email: [email protected]
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Carotid Artery Stenting Procedure
Figure 1. Structure of a fully expanded Roadsaver stent.
lesions were treated in February 2014. Five (71.4%) patients suffered from symptomatic large artery atherosclerosis (LAA),4 while 2 acute stroke patients with tandem lesions were treated prior to intracranial mechanical thrombectomy. All patients were hypertensive, and the majority (6/7) had coronary artery disease. Five of 7 had a National Institutes of Health Stroke Scale (NIHSS) score >16 at admission (mean 12.8±5.0, range 7–20), and the mean modified Rankin Scale (mRS) score was 3.7±0.7 (range 3–5). Symptom duration averaged 5 days (range 1–14) in the 5 LAA patients and 132 minutes in the 2 stroke patients. In the 5 LAA patients, the mean stenosis was 76%±8.9% (range 70–90) by NASCET criteria. The electively treated LAA lesions were evaluated in an interdisciplinary neurological/neuroradiological conference. All patients underwent pre- and postprocedure neurological examination by an independent neurologist using the NIHSS and the mRS. All patients signed an informed consent, with the exception of 2 patients treated during acute stroke management. Electively treated patients were prescribed dual antiplatelet therapy [aspirin (100 mg/d) and clopidogrel (75 mg/d after a 300-mg loading dose)] for 3 days prior to the procedure.
Roadsaver Carotid Artery Stent The dual layer design is constructed of an inner nitinol micromesh woven onto an external closed-cell stent to achieve a cell size of ~375 to 500 µm (Figure 1), one quarter that of the smallest cell size currently available. It thus acts like a covered stent to trap embolic material against the vessel wall. The device is retrievable and repositionable (recommended with up to 50% deployment). Because of the braided mesh double layer design, the stent tapers according to the anatomy, so that no tapered version is needed. The low profile enhances crossability for primary stenting. The final implanted stent length depends on the vessel diameter. For example, the central dual layer length for an 8×30-mm stent is 30 mm, but the fully deployed stent has an overall length of 40 mm. A minimum 5-F guide sheath (1.7 mm) or a minimum 7-F guide catheter (2.3 mm) is recommended.
The procedure was performed under local anesthesia in the 5 LAA cases; the 2 acute stroke patients also underwent mechanical thrombectomy of the middle cerebral artery (MCA) under general endotracheal anesthesia. No predilation was done in any case. All patients received 5000 units of heparin during the procedure as well as atropine (0.5 mg) before stent implantation. The flow after stent placement was evaluated using the Thrombolysis in Cerebral Infarction (TICI) score. The patients were continued on the dual antiplatelet therapy after the procedure. Clinical outcome was based on the NIHSS and mRS scores during hospitalization. Thirty-day morbidity and mortality were evaluated via telephone interview. The patency and flow rate of the external carotid artery (ECA) were measured with duplex ultrasound.
Results All stents were deployed satisfactorily (Figure 2) and without complications during or after the procedure. Clinical symptoms improved in the 5 LAA patients as reflected in the decline of the mRS from 3.7±0.7 to 2.4±0.8 during hospitalization. At discharge, all 5 patients had a favorable outcome (mRS 0–2); the 30-day mRS was 1.7±1.1. Ultrasound examination after 6 months (Figure 3) demonstrated patency of the ECAs in the 5 cases. In the 2 stroke patients, time to recanalization was 41 and 56 minutes, respectively. In the first case, the patient had left-sided hemiplegia owing to a ribbon sign on the right side and a hyperdense MCA as a consequence of a proximal ICA occlusion. A Roadsaver stent was deployed followed by postdilation (Figure 4) and stent-assisted thrombectomy of the MCA (TICI 3). The second patient had wall-appended thromboemboli in the proximal ICA together with an MCA occlusion. The ICA emboli were directly covered with the Roadsaver stent without postdilation (Figure 5). The thromboemboli in the occluded MCA were captured with a Solitaire Stent Retriever (Covidien) with simultaneous dual aspiration at the diagnostic and guiding catheters. Immediately after direct stenting, dual antiplatelet therapy was begun with intravenous aspirin (500 mg) followed by clopidogrel (300 mg oral through the stomach tube). TICI 2b or greater flow was achieved in both patients. No bridging therapy with recombinant tissue plasminogen activator was required. Follow-up imaging showed no hemorrhagic transformation or parenchymal hematoma.
Discussion Stent Design The main differences in currently available self-expanding stents are the patterns of struts and their interconnections;
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Figure 2. An 81-year-old patient admitted with recurrent transient ischemic attacks. (A) An 80% internal carotid artery (ICA) stenosis in an elongated vessel was treated with (B) a 7×30-mm Roadsaver Carotid Artery Stent without an embolic protection device. (C) The central dual layer segment (between arrows) formed a scaffold for plaque coverage. (D) The final angiogram after postdilation showed complete apposition to the vessel wall.
Figure 3. A 6-month follow-up Doppler ultrasound of a (A) right internal carotid artery (ICA) and (B) external carotid artery (ECA) with spectral analysis shows preserved flow with no turbulence or recurrent stenosis.
there are the open vs. closed-cell designs and the hybrid pattern, which combines a closed-cell midsection with peripheral open-cell design. Because of the individual characteristics of these stent designs, there are differences in bending stiffness, radial force, flexibility, adaptability, and conformability to the vessel and in the scaffolding to reduce plaque prolapse and embolization.5 There is a consensus, although no level I evidence, that closed-cell stents have obvious advantages over open-cell stents. Until now, the Wallstent was the first choice to
achieve good plaque coverage with less chance of plaque protrusion through the interstices. The problem with the Wallstent is seen in tortuous anatomy, where the stent cannot adapt to the wall of the artery. In tortuous anatomy, operators have chosen open-cell stents, which are very flexible and have better conformation to tortuous anatomy. Ideally, closed-cell, adaptable, and flexible stents are needed for symptomatic patients with tortuous ICA anatomy. The dual layer design of the Roadsaver Carotid Artery Stent combines the flexibility of an open-cell stent and therefore conformation to the vessel wall, as well as the higher resistance to particle penetration found in a closedcell stent. Plaque coverage is maximized by the dual layer micromesh design, which has been established in flow diverter technology used in endovascular intracranial treatment of wide neck aneurysms.6 W.L. Gore has recently introduced a new hybrid stent with a similar concept.7 Although CAS has emerged as a minimally invasive alternative to endarterectomy, there are unanswered questions regarding adverse events such as in-stent restenosis and late thrombosis.8 Hemodynamic factors related to blood flow in the stented vessel have been suggested as factors in the response of the endothelium to stenting.8
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Figure 4. (A) Angiogram of a 54-year-old woman with an occluded right internal carotid artery (ICA) in the context of ischemic stroke with tandem ICA/middle cerebral artery occlusion. (B) After passing the high-grade atherosclerotic stenosis, (C) a 7×25mm Roadsaver stent was directly deployed. (D) After postdilation with moderate radial force in a possible vulnerable stenosis, (E) mechanical thrombectomy was performed (straight arrow, intermediate DAC catheter; angulated arrow, Rebar microcatheter). After Solitaire stent–assisted clot retrieval, the final angiogram (F) showed complete recanalization (Thrombolysis in Cerebral Infarction score 3).
With respect to late embolization, several studies have not been able to prove superiority of any stent design. For example, Bosiers et al9 retrospectively assessed a CAS database of 3179 consecutive CAS patients and reported a higher postprocedure complication rate for open-cell types and increasing risk with a larger free-cell area. Conti et al10 evaluated the impact of stent cell design on vessel scaffolding by using patient-specific finite element analysis of CAS. The measured interstrut angles suggested that the closed-cell design provided superior vessel scaffolding compared with the open-cell design. The full strut interconnection of the closed-cell design reduced the stent’s ability to accommodate to an irregular eccentric profile of the vessel cross section, leading to a gap between the stent surface and the vessel wall.10 In our first clinical experience in a small cohort with short-term follow-up, the Roadsaver stent presented no problems in navigating through the supra-aortic vessels in the aortic arch types 1 to 3 or in straight or elongated ICAs. We did not register any pre- or postprocedure complications related to embolic release; surveillance ultrasound scans documented good wall apposition in all patients. Ultrasound has so far documented the patency of the ECA in all patients.
Some might question the decision to perform CAS without embolic protection, but several studies have reported excellent results of CAS without protection devices.11–19 Complications and mortality rates were similar to studies that used protection devices.11–13 Furthermore, a subanalysis of data from the SPACE trial did not support the need for protection devices.13 Based on our positive and encouraging data from previous evaluations,14 no cerebral protection devices were used in this study. However, studies are needed to evaluate if this stent design needs any cerebral protection device during the index procedure.
Tandem Lesions in Ischemic Stroke Recanalization of occluded arteries is crucial for good functional outcome in the context of acute stroke.20 Up to now, the evidence-based recommended therapy has been thrombolysis, but mechanical thrombectomy is playing an increasing role in endovascular treatment of large vessel occlusion. Some patients have additional extracranial cervical carotid artery occlusion or severe stenosis.21 Several studies confirm the technical feasibility of endovascular recanalization with emergency CAS.20,21 A discussion point is the risk of hemorrhage
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Figure 5. A 73-year-old man admitted with acute stroke referable to tandem internal carotid artery (ICA) thromboemboli and middle cerebral artery occlusion. (A) Cervical angiography showed the wall-adherent fresh thromboemboli at the origin of the left ICA. (B) Distal vasospasm. (C) Implantation of 6×30-mm Roadsaver stent to cover the thromboemboli. The vasospasm resolved.
in combination with anticoagulation therapy. In our patients, the implanted Roadsaver stent was easily passed with a coaxial diagnostic catheter to start intracranial thrombectomy.
Conclusion The Roadsaver double layer micromesh stent design appears to be safe and effective, with sufficient radial force and vessel conformability to treat extracranial ICA stenoses and tandem lesions in the endovascular management of ischemic stroke. The necessity of an embolic protection device with this stent should be further investigated. Declaration of Conflicting Interests The author(s) declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.
References 1. Schillinger M, Minar E. Matching carotid anatomy with carotid stents. J Cardiovasc Surg (Torino). 2008;49:723–727. 2. Khan M, Qureshi AI. Factors associated with increased rates of post-procedural stroke or death following carotid artery
stent placement: a systematic review. J Vasc Interv Neurol. 2014;7:11–20. 3. Bosiers M, Deloose K, Verbist J, et al. Carotid artery stenting: which stent for which lesion? Vascular. 2005;13:205–210. 4. Adams HP Jr, Bendixen BH, Kappelle LJ, et al. Classification of subtype of acute ischemic stroke. Definitions for use in a multicenter clinical trial. TOAST. Trial of Org 10172 in Acute Stroke Treatment. Stroke. 1993;24:35–41. 5. Müller-Hülsbeck S, Preuss H, Elhöft H. CAS: which stent for which lesion. J Cardiovasc Surg (Torino). 2009;50:767–772. 6. Alderazi YJ, Shastri D, Kass-Hout T, et al. Flow diverters for intracranial aneurysms. Stroke Res Treat. 2014;2014:415653. 7. Schönholz C, Yamada R, Montgomery W, et al. First-in-man implantation of a new hybrid carotid stent to prevent periprocedural neurological events during carotid artery stenting. J Endovasc Ther. 2014;21:601–604. 8. De Santis G, Conti M, Trachet B, et al. Haemodynamic impact of stent-vessel (mal)apposition following carotid artery stenting: mind the gaps! Comput Methods Biomech Biomed Eng. 2013;16:648–659. 9. Bosiers M, de Donato G, Deloose K, et al. Does free cell area influence the outcome in carotid artery stenting? Eur J Vasc Endovasc Surg. 2007;33:135–141. 10. Conti M, Van Loo D, Auricchio F, et al. Impact of carotid stent cell design on vessel scaffolding: a case study comparing experimental investigation and numerical simulations. J Endovasc Ther. 2011;18:397–406. 11. Oteros R, Jimenez-Gomez E, Bravo-Rodriguez F, et al. Unprotected carotid artery stenting in symptomatic patients
Hopf-Jensen et al with high-grade stenosis: results and long-term followup in a single-center experience. AJNR Am J Neuroradiol. 2012;33:1285–1291. 12. Jimenez-Gomez E, Cano Sánchez A, Oteros Fernández R, et al. Unprotected carotid artery stenting in symptomatic elderly patients: a single-center experience [published online April 12, 2014]. J Neurointerv Surg. doi:10.1136/neurintsurg2014-011131. 13. Jansen O, Fiehler J, Hartmann M, et al. Protection or nonprotection in carotid stent angioplasty: the influence of interventional techniques on outcome data from the SPACE Trial. Stroke. 2009;40:841–846. 14. Hopf-Jensen S, Marques L, Preiß M, et al. Lesion-related carotid angioplasty and stenting with closed-cell design without embolic protection devices in high-risk elderly patients— can this concept work out? A single center experience focusing on stent design. Int J Angiol. 2014;23:263–270. 15. Maynard M, Baldi S, Rostagno R, et al. Carotid stenting without use of balloon angioplasty and distal protection devices: preliminary experience in 100 cases. AJNR Am J Neuroradiol. 2007;28:1378–1383.
225 16. Tietke MW, Kerby T, Alfke K, et al. Complication rate in unprotected carotid artery stenting with closed-cell stents. Neuroradiology. 2010;52:611–618. 17. Mohammadian R, Sohrabi B, Mansourizadeh R, et al. Unprotected carotid artery stenting: complications in 6 months follow-up. Neuroradiology. 2012;54:225–230. 18. Baldi S, Zander T, Rabellino M, et al. Carotid artery stenting without angioplasty and cerebral protection: a singlecenter experience with up to 7 years’ follow-up. AJNR Am J Neuroradiol. 2011;32:759-763. 19. Mansour OY, Weber J, Niesen W, et al. Carotid angioplasty and stenting without protection devices: safety and efficacy concerns—single center experience. Clin Neuroradiol. 2011;2:65–73 20. Ohara N, Tateshima S, Sayre J, et al. E-074 Emergency carotid artery stenting in acute ischemic stroke [abstract]. J Neurointerv Surg. 2014;6(suppl 1):A74. 21. Cohen JE, Gomori JM, Rajz G, et al. Extracranial carotid artery stenting followed by intracranial stent-based thrombectomy for acute tandem occlusive disease [published online April 14, 2014]. J Neurointerv Surg. doi: 10.1136/neurintsurg-2014-011175.
research-article2015
JETXXX10.1177/1526602815576337Journal of Endovascular TherapyHopf-Jensen et al
Clinical Investigation
Initial Clinical Experience With the Micromesh Roadsaver Carotid Artery Stent for the Treatment of Patients With Symptomatic Carotid Artery Disease
Journal of Endovascular Therapy 2015, Vol. 22(2) 220–225 © The Author(s) 2015 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1526602815576337 www.jevt.org
Silke Hopf-Jensen, MD1, Leonardo Marques, MD1, Michael Preiß, MD1, and Stefan Müller-Hülsbeck, MD, EBIR, PhD1
Abstract Purpose: To assess the effectiveness, technical aspects, handling, and safety of the micromesh Roadsaver Carotid Artery Stent in the treatment of atherosclerotic carotid artery stenosis and tandem lesions in ischemic stroke patients. Methods: Seven patients (5 men; mean age 75±11.4 years, range 53–86) suffering from symptomatic internal carotid artery (ICA) stenosis (mean 76% diameter reduction) were treated with the dual layer closed-cell stent without embolic protection. Postdilation was performed in 6 of 7 patients. Two patients were treated in the context of ischemic stroke and concurrent middle cerebral artery occlusion. Mean National Institutes of Health Stroke Scale score at admission was 12.8±5. Results: All devices were deployed satisfactorily. One wall-adherent thromboembolus in a proximal ICA was covered with the Roadsaver stent in a tandem lesion setting. The modified Rankin Scale (mRS) declined from 3.7±0.7 to 2.4±0.8 in hospital, showing an improvement in clinical symptoms. No complications were detected during or after the procedure. The 30-day mRS was 1.7±1.1. At 6 months, ultrasound examination demonstrated patency of stents and the external carotid arteries. Conclusion: The Roadsaver double layer micromesh stent seems to be safe and effective in the treatment of extracranial ICA stenosis and in the context of tandem lesions in ischemic stroke. Further studies with larger populations are warranted. Keywords carotid artery disease, carotid artery stent, internal carotid artery, stenosis, stroke, tandem lesion, closed-cell stent, opencell stent, nitinol mesh, dual layer stent
Introduction The complication rates of carotid artery stenting (CAS) have continuously decreased over recent years due to technical improvements, operator experience, a lesion-tailored interventional strategy,1 better patient selection, and improved stent design. Stent design can be classified into either open or closedcell configurations2,3 or a hybrid-cell configuration based on the density of the struts. Different materials (nitinol or cobalt–chromium) and shapes (tapered vs. straight) of carotid artery stents provide a range of geometries and mechanical properties.3 Characteristics such as high flexibility are needed to preserve vessel contours, and radial force, wall apposition, and plaque coverage are required to prevent late embolic release. Despite the variety of available carotid artery stents, there remains the desire to develop and improve the materials and designs in order to achieve sustained, permanent embolic protection.
Our aim is to demonstrate the effectiveness, technical aspects, handling, and safety of the micromesh Roadsaver Carotid Artery Stent (Terumo, Tokyo, Japan) in the treatment of extracranial carotid artery disease.
Methods Patient Population Seven patients (5 men; mean age 75±11.4 years, range 53–86) with underlying internal carotid artery (ICA) 1
Department of Diagnostic and Interventional Radiology and Neuroradiology, Diakonissenhospital Flensburg, Germany Corresponding Author: Silke Hopf-Jensen, Department of Diagnostic and Interventional Radiology/Neuroradiology, Diakonissenhosptal Flensburg, Knuthstraße 1, 24939 Flensburg, Germany. Email: [email protected]
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Carotid Artery Stenting Procedure
Figure 1. Structure of a fully expanded Roadsaver stent.
lesions were treated in February 2014. Five (71.4%) patients suffered from symptomatic large artery atherosclerosis (LAA),4 while 2 acute stroke patients with tandem lesions were treated prior to intracranial mechanical thrombectomy. All patients were hypertensive, and the majority (6/7) had coronary artery disease. Five of 7 had a National Institutes of Health Stroke Scale (NIHSS) score >16 at admission (mean 12.8±5.0, range 7–20), and the mean modified Rankin Scale (mRS) score was 3.7±0.7 (range 3–5). Symptom duration averaged 5 days (range 1–14) in the 5 LAA patients and 132 minutes in the 2 stroke patients. In the 5 LAA patients, the mean stenosis was 76%±8.9% (range 70–90) by NASCET criteria. The electively treated LAA lesions were evaluated in an interdisciplinary neurological/neuroradiological conference. All patients underwent pre- and postprocedure neurological examination by an independent neurologist using the NIHSS and the mRS. All patients signed an informed consent, with the exception of 2 patients treated during acute stroke management. Electively treated patients were prescribed dual antiplatelet therapy [aspirin (100 mg/d) and clopidogrel (75 mg/d after a 300-mg loading dose)] for 3 days prior to the procedure.
Roadsaver Carotid Artery Stent The dual layer design is constructed of an inner nitinol micromesh woven onto an external closed-cell stent to achieve a cell size of ~375 to 500 µm (Figure 1), one quarter that of the smallest cell size currently available. It thus acts like a covered stent to trap embolic material against the vessel wall. The device is retrievable and repositionable (recommended with up to 50% deployment). Because of the braided mesh double layer design, the stent tapers according to the anatomy, so that no tapered version is needed. The low profile enhances crossability for primary stenting. The final implanted stent length depends on the vessel diameter. For example, the central dual layer length for an 8×30-mm stent is 30 mm, but the fully deployed stent has an overall length of 40 mm. A minimum 5-F guide sheath (1.7 mm) or a minimum 7-F guide catheter (2.3 mm) is recommended.
The procedure was performed under local anesthesia in the 5 LAA cases; the 2 acute stroke patients also underwent mechanical thrombectomy of the middle cerebral artery (MCA) under general endotracheal anesthesia. No predilation was done in any case. All patients received 5000 units of heparin during the procedure as well as atropine (0.5 mg) before stent implantation. The flow after stent placement was evaluated using the Thrombolysis in Cerebral Infarction (TICI) score. The patients were continued on the dual antiplatelet therapy after the procedure. Clinical outcome was based on the NIHSS and mRS scores during hospitalization. Thirty-day morbidity and mortality were evaluated via telephone interview. The patency and flow rate of the external carotid artery (ECA) were measured with duplex ultrasound.
Results All stents were deployed satisfactorily (Figure 2) and without complications during or after the procedure. Clinical symptoms improved in the 5 LAA patients as reflected in the decline of the mRS from 3.7±0.7 to 2.4±0.8 during hospitalization. At discharge, all 5 patients had a favorable outcome (mRS 0–2); the 30-day mRS was 1.7±1.1. Ultrasound examination after 6 months (Figure 3) demonstrated patency of the ECAs in the 5 cases. In the 2 stroke patients, time to recanalization was 41 and 56 minutes, respectively. In the first case, the patient had left-sided hemiplegia owing to a ribbon sign on the right side and a hyperdense MCA as a consequence of a proximal ICA occlusion. A Roadsaver stent was deployed followed by postdilation (Figure 4) and stent-assisted thrombectomy of the MCA (TICI 3). The second patient had wall-appended thromboemboli in the proximal ICA together with an MCA occlusion. The ICA emboli were directly covered with the Roadsaver stent without postdilation (Figure 5). The thromboemboli in the occluded MCA were captured with a Solitaire Stent Retriever (Covidien) with simultaneous dual aspiration at the diagnostic and guiding catheters. Immediately after direct stenting, dual antiplatelet therapy was begun with intravenous aspirin (500 mg) followed by clopidogrel (300 mg oral through the stomach tube). TICI 2b or greater flow was achieved in both patients. No bridging therapy with recombinant tissue plasminogen activator was required. Follow-up imaging showed no hemorrhagic transformation or parenchymal hematoma.
Discussion Stent Design The main differences in currently available self-expanding stents are the patterns of struts and their interconnections;
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Journal of Endovascular Therapy 22(2)
Figure 2. An 81-year-old patient admitted with recurrent transient ischemic attacks. (A) An 80% internal carotid artery (ICA) stenosis in an elongated vessel was treated with (B) a 7×30-mm Roadsaver Carotid Artery Stent without an embolic protection device. (C) The central dual layer segment (between arrows) formed a scaffold for plaque coverage. (D) The final angiogram after postdilation showed complete apposition to the vessel wall.
Figure 3. A 6-month follow-up Doppler ultrasound of a (A) right internal carotid artery (ICA) and (B) external carotid artery (ECA) with spectral analysis shows preserved flow with no turbulence or recurrent stenosis.
there are the open vs. closed-cell designs and the hybrid pattern, which combines a closed-cell midsection with peripheral open-cell design. Because of the individual characteristics of these stent designs, there are differences in bending stiffness, radial force, flexibility, adaptability, and conformability to the vessel and in the scaffolding to reduce plaque prolapse and embolization.5 There is a consensus, although no level I evidence, that closed-cell stents have obvious advantages over open-cell stents. Until now, the Wallstent was the first choice to
achieve good plaque coverage with less chance of plaque protrusion through the interstices. The problem with the Wallstent is seen in tortuous anatomy, where the stent cannot adapt to the wall of the artery. In tortuous anatomy, operators have chosen open-cell stents, which are very flexible and have better conformation to tortuous anatomy. Ideally, closed-cell, adaptable, and flexible stents are needed for symptomatic patients with tortuous ICA anatomy. The dual layer design of the Roadsaver Carotid Artery Stent combines the flexibility of an open-cell stent and therefore conformation to the vessel wall, as well as the higher resistance to particle penetration found in a closedcell stent. Plaque coverage is maximized by the dual layer micromesh design, which has been established in flow diverter technology used in endovascular intracranial treatment of wide neck aneurysms.6 W.L. Gore has recently introduced a new hybrid stent with a similar concept.7 Although CAS has emerged as a minimally invasive alternative to endarterectomy, there are unanswered questions regarding adverse events such as in-stent restenosis and late thrombosis.8 Hemodynamic factors related to blood flow in the stented vessel have been suggested as factors in the response of the endothelium to stenting.8
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Figure 4. (A) Angiogram of a 54-year-old woman with an occluded right internal carotid artery (ICA) in the context of ischemic stroke with tandem ICA/middle cerebral artery occlusion. (B) After passing the high-grade atherosclerotic stenosis, (C) a 7×25mm Roadsaver stent was directly deployed. (D) After postdilation with moderate radial force in a possible vulnerable stenosis, (E) mechanical thrombectomy was performed (straight arrow, intermediate DAC catheter; angulated arrow, Rebar microcatheter). After Solitaire stent–assisted clot retrieval, the final angiogram (F) showed complete recanalization (Thrombolysis in Cerebral Infarction score 3).
With respect to late embolization, several studies have not been able to prove superiority of any stent design. For example, Bosiers et al9 retrospectively assessed a CAS database of 3179 consecutive CAS patients and reported a higher postprocedure complication rate for open-cell types and increasing risk with a larger free-cell area. Conti et al10 evaluated the impact of stent cell design on vessel scaffolding by using patient-specific finite element analysis of CAS. The measured interstrut angles suggested that the closed-cell design provided superior vessel scaffolding compared with the open-cell design. The full strut interconnection of the closed-cell design reduced the stent’s ability to accommodate to an irregular eccentric profile of the vessel cross section, leading to a gap between the stent surface and the vessel wall.10 In our first clinical experience in a small cohort with short-term follow-up, the Roadsaver stent presented no problems in navigating through the supra-aortic vessels in the aortic arch types 1 to 3 or in straight or elongated ICAs. We did not register any pre- or postprocedure complications related to embolic release; surveillance ultrasound scans documented good wall apposition in all patients. Ultrasound has so far documented the patency of the ECA in all patients.
Some might question the decision to perform CAS without embolic protection, but several studies have reported excellent results of CAS without protection devices.11–19 Complications and mortality rates were similar to studies that used protection devices.11–13 Furthermore, a subanalysis of data from the SPACE trial did not support the need for protection devices.13 Based on our positive and encouraging data from previous evaluations,14 no cerebral protection devices were used in this study. However, studies are needed to evaluate if this stent design needs any cerebral protection device during the index procedure.
Tandem Lesions in Ischemic Stroke Recanalization of occluded arteries is crucial for good functional outcome in the context of acute stroke.20 Up to now, the evidence-based recommended therapy has been thrombolysis, but mechanical thrombectomy is playing an increasing role in endovascular treatment of large vessel occlusion. Some patients have additional extracranial cervical carotid artery occlusion or severe stenosis.21 Several studies confirm the technical feasibility of endovascular recanalization with emergency CAS.20,21 A discussion point is the risk of hemorrhage
224
Journal of Endovascular Therapy 22(2)
Figure 5. A 73-year-old man admitted with acute stroke referable to tandem internal carotid artery (ICA) thromboemboli and middle cerebral artery occlusion. (A) Cervical angiography showed the wall-adherent fresh thromboemboli at the origin of the left ICA. (B) Distal vasospasm. (C) Implantation of 6×30-mm Roadsaver stent to cover the thromboemboli. The vasospasm resolved.
in combination with anticoagulation therapy. In our patients, the implanted Roadsaver stent was easily passed with a coaxial diagnostic catheter to start intracranial thrombectomy.
Conclusion The Roadsaver double layer micromesh stent design appears to be safe and effective, with sufficient radial force and vessel conformability to treat extracranial ICA stenoses and tandem lesions in the endovascular management of ischemic stroke. The necessity of an embolic protection device with this stent should be further investigated. Declaration of Conflicting Interests The author(s) declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.
References 1. Schillinger M, Minar E. Matching carotid anatomy with carotid stents. J Cardiovasc Surg (Torino). 2008;49:723–727. 2. Khan M, Qureshi AI. Factors associated with increased rates of post-procedural stroke or death following carotid artery
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