Article Text


Case series
Crossing Y-Solitaire thrombectomy as a rescue treatment for refractory acute occlusions of the middle cerebral artery
  1. Kubilay Aydin1,2,
  2. Mehmet Barburoglu2,
  3. Ozgur Oztop Cakmak3,
  4. Nilufer Yesilot4,
  5. Ebru Nur Yavuz Vanli3,
  6. Sergin Akpek5
  1. 1 Department of Neuroradiology, Istanbul University, Istanbul Faculty of Medicine, Istanbul, Turkey
  2. 2 Department of Radiology, Interventional Neuroradiology Unit, Koc University School of Medicine, Koc University Hospital, Istanbul, Turkey
  3. 3 Department of Neurology, Koc University School of Medicine, Koc University Hospital, Istanbul, Turkey
  4. 4 Department of Neurology, Istanbul University, Istanbul Faculty of Medicine, Istanbul, Turkey
  5. 5 Department of Radiology, VKV American Hospital, Istanbul, Turkey
  1. Correspondence to Professor Kubilay Aydin, Department of Neuroradiology, Istanbul University, IstanbulFaculty of Medicine, Istanbul 34452, Turkey; dr.aydink{at}


Background Mechanical thrombectomy using a stent retriever has become the standard of care for acute large-vessel occlusions in the anterior circulation. Clots that are refractory to single stent retriever thrombectomy remain a challenge for neurointerventionalists.

Objective To assess the efficacy and safety of double stent retriever (crossing Y-Solitaire) thrombectomy as a rescue treatment for acute middle cerebral artery (MCA) occlusions that are refractory to single stent retriever thrombectomy.

Methods We retrospectively reviewed the databases of our hospitals to identify patients who presented with an acute MCA occlusion and were treated with crossing Y-Solitaire thrombectomy. The angiographic (Thrombolysis in Cerebral Infarction (TICI) scale) and clinical outcomes (National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) scores) and complications were assessed.

Results Ten patients were included in the study. The median initial NIHSS score and Alberta Stroke Program Early CT Score (ASPECTS) were 19.0 and 9.6, respectively. Crossing Y-Solitaire thrombectomy was performed as a rescue technique after unsuccessful single Solitaire thrombectomy passes in all cases. Successful recanalization (TICI 2b/3) was achieved in 8 (80%) patients. We observed asymptomatic reperfusion hemorrhages in 2 (20%) patients. No procedural related complications were seen other than reversible vasospasms in 5 (50%) patients. Sixty percent of the patients had a mRS score of between 2 and 0 at 90 days after the procedure. There was no mortality.

Conclusion Crossing Y-Solitaire thrombectomy seems to be an effective and safe alternative rescue technique to treat refractory MCA bifurcation occlusions that are refractory to standard thrombectomy procedures.

  • stroke
  • thrombectomy
  • intervention
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After the publication of recent randomized controlled trials, mechanical thrombectomy using stent retrievers (SRs) has become the standard treatment of patients with acute occlusions of proximal arteries of the anterior circulation.1–5 The clinical outcome of patients treated with mechanical thrombectomy is strongly associated with successful recanalization. However, the standard SR thrombectomy procedure fails to achieve successful recanalization in 12–29% of patients.1–5 Various rescue treatments, such as direct aspiration with large-bore intermediate catheters, intra-arterial infusion of tissue plasminogen activator (tPA) or glycoprotein IIb/IIIa inhibitors, balloon angioplasty and permanent stent placement, have been reported to achieve successful recanalization in cases that are refractory to SR thrombectomy.6–11 However, the rates of effective recanalization following these rescue treatment methods remain low.

Simultaneous use of double SRs in a crossing Y configuration as a rescue thrombectomy technique to treat refractory bifurcation occlusions has been recently reported in a few case reports.12 13 This technique is based on the deployment of two SRs, passing one stent through the struts of the other, into the daughter branches of the bifurcation and simultaneous retrieval of both SRs. In previous case reports, combinations of various SR devices (Solitaire (Medtronic, Minneapolis, Minnesota, USA), Catch (Balt, Montmorency, France), and two Trevo SRs (Stryker Neurovascular, Kalamazoo, Michigan, USA)) in a crossing Y configuration achieved effective recanalization of middle cerebral arteries (MCAs) that were refractory to the standard single SR thrombectomy.12 13 In this retrospective study, we aimed to assess the efficacy and safety of the double SR thrombectomy technique using two Solitaire SRs (Medtronic) in a crossing Y configuration to treat acute occlusions of the MCA bifurcation that were refractory to standard single SR thrombectomy. We refer to this technique as crossing Y-Solitaire thrombectomy.

Patients and methods


After approval of the study by the institutional review board, retrospective reviews of the interventional database records of three hospitals were performed to identify patients who presented with acute ischemic stroke due to an acute MCA occlusion and were treated by the crossing Y-Solitaire thrombectomy technique as a rescue therapy. At our institutions, patients presenting with acute ischemic stroke are assessed using plain CT and CT angiography to decide which treatment method to use. Use of endovascular thrombectomy is indicated by the presence of all of the following: (1) a National Institutes of Health Stroke Scale (NIHSS) score ≥4, (2) an Alberta Stroke Programme Early CT Score (ASPECTS) ≥7, (3) occlusion of the internal carotid artery or MCA trunk or its immediate branches, and (4) initiation of endovascular treatment within 6 hours after symptom onset.

For this study, medical records and radiological images of the included patients were gathered. The patients’ demographic data and preprocedural NIHSS and ASPECT scores were recorded.

Endovascular procedure

Y-Solitaire thrombectomy procedures were performed only as a rescue treatment following the failure of a first-line standard single SR thrombectomy procedure. Every endovascular procedure was performed using a femoral approach with the patient under general anesthesia. The standard SR thrombectomy procedure was performed as described previously using a 9F Cello balloon-guiding catheter (Medtronic) and a Solitaire SR (Medtronic) with a size of 6×30 mm and 4×20 mm.11 The dominant MCA trunk determined on pretreatment CT angiography images was chosen for the first single Solitaire passses.14 Standard single Solitaire passes were repeated 3–5 times to achieve a Thrombolysis in Cerebral Infarction (TICI) score of 2b or 3 until the crossing Y-Solitaire thrombectomy was initiated.

For the crossing Y-Solitaire thrombectomy, one of the occluded MCA trunks was catheterized with a 0.27 or 0.21 inch microcatheter (Headway 27 (Microvention, Tustin, California, USA) or Rebar 27 or 18 (Medtronic)) using a 0.014 inch guidewire ((Traxcess (Microvention) or Synchro (Stryker)). A Solitaire SR device with a size of 6×30 mm or 4×20 mm was deployed across the occluding thrombus, extending from the catheterized M2 branch of the MCA to the M1 segment proximal to the thrombus. Then, a new roadmap image was obtained to use for the catheterization of the second M2 branch. The second M2 branch was catheterized with a 0.21 inch microcatheter ((Headway 21 (Microvention) or Rebar 18 (Medtronic)) by passing the catheter through the struts of the first deployed Solitaire SR. A second Solitaire SR with a size of 4×20 mm was deployed, extending from the second M2 branch into the M1 trunk to create a crossing Y configuration together with the first deployed Solitaire SR. Control angiography was performed to assess the positions of the deployed SRs, the re-establishment of blood flow, and the interaction of the SRs with the thrombus. One of the microcatheters was removed just before retrieval of the Solitaire SRs to allow more space in the guiding catheter for more effective aspiration.

Finally, after the flow in the internal carotid artery was arrested by balloon inflation via the guiding catheter, both Solitaire SRs were slowly retrieved by simultaneously pulling them together into the guiding catheter under continuous aspiration with a 50 mL syringe. The Y connector was released from the hub of the guiding catheter to allow removal of the intertwined SRs. The lumen of the guiding catheter was re-aspirated with a 50 mL syringe before restoration of the flow in the internal carotid artery by deflation of the balloon. A control angiogram was obtained to assess the recanalization. The femoral puncture was closed using a vessel closure device (Angio-Seal; St Jude Medical, Minnetonka, Minnesota, USA). Neither IV heparin nor IA fibrinolytic agents or antiplatelets were administered during the procedure.

The time from symptom onset to groin puncture and the time from groin puncture to the final image demonstrating recanalization were recorded. The number of failed single SR passes before the initiation of Y-Solitaire thrombectomy, application of other rescue recanalization methods, and procedural complications were recorded.


Recanalization of the target artery was assessed by two experienced neuroradiologists using the TICI score. A TICI score of 2b or 3 was defined as successful recanalization. A control cranial CT examination was performed at the end of the procedure to screen for any complications or immediate reperfusion hemorrhage. A second cranial CT or MR examination was performed 24 hours after termination of the endovascular procedure to assess the extent of the final infarction and the development of reperfusion hemorrhage. Intracranial hemorrhage was classified according to the European Cooperative Acute Stroke Study (ECASS) criteria.15 Clinical assessment was performed 24 hours after completion of the procedure using the NIHSS score. Functional outcomes of the patients were assessed according to the modified Rankin Scale (mRS) score at hospital discharge and 90 days after the stroke by two experienced neurologists who were blinded to the technical details of the treatment procedure.


Ten patients (5 female and five male) were included in the study. The mean age of the patients was 69.8 years (range 34–83). The median presenting NIHSS and ASPECT scores were 19.0 (range 16–22) and 9.6 (range 8–10), respectively. Three patients received IV tPA infusion (tPA dose; 0.9 mg/kg) before the endovascular thrombectomy. The median number of failed single SR passes was 3.5 (range 3–5). In two patients, direct aspiration using a large-bore intermediate catheter was attempted as the first rescue treatment before the initiation of crossing Y-Solitaire thrombectomy. In the remaining eight patients, crossing Y-Solitaire thrombectomy was performed as the first rescue treatment procedure following multiple unsuccessful single SR passes (figure 1). The technical success of the crossing Y-Solitaire thrombectomy, defined as successful deployment of two Solitaire SRs in a Y configuration across the thrombus, was 100% (figure 2). The crossing Y-Solitaire technique achieved a TICI 2b or 3 recanalization in eight (80%) of the patients at the first Y-Solitaire pass. In two patients, crossing Y-Solitaire passes were repeated twice, and the mechanical thrombectomy procedures were completed with the achievement of a TICI 2a recanalization. The median time from symptom onset to groin puncture was 174 min (range 125–235). In addition, the median time from groin puncture to final recanalization, including time spent on unsuccessful standard single SR passes, was 48.9 min (range 34–65). No procedure-related complication occurred other than a minor or moderate degree of vasospasm in the proximal M1 or M2 segment of the MCA in five patients. The control CT examinations at 24 hours revealed the asymptomatic reperfusion hemorrhage as small petechiae and confluent petechiae without space-occupying hemorrhage (HI-1 and 2 type hemorrhage) in two patients.

Figure 1

Procedural angiography images of a patient with an acute left middle cerebral artery (MCA) occlusion. (A) The initial DSA image obtained at the beginning of mechanical thrombectomy shows the total occlusion of the left MCA. (B) A DSA image obtained during the deployment of a single Solitaire stent retriever (SR) into the left MCA across the thrombus shows the restoration of the flow in the M1 segment and inferior truncus. (C) A control DSA image obtained just after the third pass of a single Solitaire demonstrates the persistent occlusion and vasospasm (arrow) in the proximal M1 segment caused by the single SR passes. (D and E) Non-substracted and subtracted control DSA images demonstrated the deployment of two Solitaire SRs extending from the M2 branches into the M1 segment (arrow and arrowhead show the distal markers of the Solitaire SRs in the MCA branches). (F and G), Anteroposterior and lateral DSA images obtained following the first pass of the crossing Y-Solitaire demonstrate the complete recanalization of the MCA (Thrombolysis in Cerebral Infarction 3 reperfusion).

Figure 2

Photograph of the intertwined Solitaire stent retrievers (SRs) taken following a crossing Y-Solitaire thrombectomy procedure. The capture of the thrombus by two Solitaire SRs deployed in a crossing Y configuration is shown.

The median NIHSS score at 24 hours after the completion of thrombectomy was 7 (range 4–14). The mRS score for five patients was between 0 and 2 at hospital discharge. Six patients (60%) had a mRS score of between 0 and 2 at 90 days. The mRS score of the other four patients was 3 at 90 days' follow-up.


The goal of mechanical thrombectomy treatment is to restore the arrested blood flow in the affected vascular territory and to salvage the ischemic brain tissue that is at risk of permanent damage. In addition, the main predictor of a good clinical outcome is successful recanalization, indicated by complete or greater than 50% filling of the distal branches in the expected territory (TICI 2b/3).16 Nevertheless, according to the results of randomized trials, successful recanalization is not achieved in approximately 12–29% of patients.1–5 Although the recently developed thrombectomy techniques that combine stent retrieval with aspiration via intermediate large-bore catheters have significantly increased the success rate of mechanical thrombectomy, there are still refractory cases.3 17–19 So, the approximately 10–15% of thrombi that are resistant to the current retrieval procedures remain a challenge for neurointerventionalists.3 9 20 21

In cases that are refractory to the standard SR thrombectomy procedure, various rescue treatments have been described, such as direct aspiration of the thrombus with a large-bore intermediate catheter, intra-arterial thrombolytic or antiplatelet (glycoprotein IIb/IIIa) drug infusions, balloon angioplasty, and permanent stenting as a final option.6–11 In a large case series, Kurre et al performed all these rescue treatments after three unsuccessful SR passes, and they found that the likelihood of a favorable outcome decreased with the application of any of these treatments.10 Raychev et al22 reported that the rescue therapy with intra-arterial recombinant tPA strongly correlated with the development of intracranial hemorrhage. Kellert et al reported that antiplatelet infusion during endovascular thrombectomy was significantly associated with fatal intracranial hemorrhages and poor outcomes.23 Lapergue et al9 reported that 23% of the patients in whom stent retrieval was performed as the first-line thrombectomy treatment required a rescue treatment. The use of a rescue treatment, including contact aspiration, combined contact aspiration and stent retrieval, balloon angioplasty, or permanent stenting, could not achieve sufficient recanalization in 35% of the cases who were refractory to standard stent retrieval. In addition, in approximately 14% of all patients, sufficient recanalization could not be achieved despite the use of a rescue therapy. The results of another study showed that in patients with acute proximal vessel occlusion that was refractory to SR thrombectomy, permanent stenting in addition to aspiration with an intermediate catheter and/or intra-arterial antiplatelet infusion as the rescue treatment could not achieve TICI 2b/3 recanalization in 16% of cases.7 The results of previous studies indicate that there is no ideal rescue treatment that can give satisfactory results in all refractory cases.

The successful retrieval of a thrombus depends on the interactions of the thrombus with the SR device and vessel wall. Ideal interaction for successful thrombectomy is that the retrieval force transmitted to the thrombus by the SR device exceeds the inertial forces created by the friction between the clot and the vessel wall.24 During the thrombectomy, expansion of the SR causes embedding of the thrombus into the inner lumen of the device, which is referred to as integration of the thrombus. Integration of the thrombus increases the retrieval force transmitted to the thrombus and enhances the chance of a successful thrombectomy. The integration of the thrombus with the SR device depends on the size, length, and composition of the thrombus as well as the mechanical properties of the SR device. In vitro experiments demonstrated that the amount of thrombus integration was inversely correlated with the fibrin content of the thrombus.24 In addition, higher radial forces for a SR device are needed to penetrate a fibrin-rich thrombus than for a red-blood-rich thrombus.24 25 So, the radial force of a single SR device may not be sufficient to penetrate a hard, fibrin-rich thrombus. The composition of the thrombus also affects its coefficient of friction with the vessel wall.26 Thrombi with a relatively higher fibrin content have a much higher coefficient of friction, which contributes to the resistance of a thrombus to retrieval during mechanical thrombectomy. Clot burden is another factor affecting the success of a thrombectomy procedure. The inertial forces created by the friction between the thrombus and the vessel wall increase with the length and extension of the thrombus. So, a long M1 thrombus extending into multiple branches of a bifurcation requires a higher retrieval force for a successful thrombectomy. Therefore, gripping only the proximal part of a saddle thrombus by a SR may not be sufficient to remove it completely.

In our study, crossing Y-Solitaire thrombectomy achieved successful recanalization (TICI 2b/3) in 80% of cases of acute MCA occlusion that were refractory to the standard single SR procedure. In addition, 60% of our cases had a good clinical outcome at 90 days (mRS score ≤2 at 90 days) which is comparable to the outcome for patients who were treated by stent retriever thrombectomy in the previous trials.1–5 Our results demonstrate that crossing Y-Solitaire thrombectomy is a promising alternative rescue technique that seems to be effective for achieving sufficient recanalization in refractory occlusions of MCA bifurcations.

The crossing Y-Solitaire technique may have some potential advantages for successful retrieval of refractory MCA bifurcation clots. First, in the crossing Y-Solitaire technique, the radial force of the second deployed SR might contribute to expansion of the first stent and thus facilitate thrombus integration.24 To enhance expansion of SRs for better thrombus integration, we used the ‘active pushing technique’ during the deployment of SRs.24 25 In a recent study, Wiesmann et al showed that use of the pushing technique during deployment significantly enhances expansion of the Solitaire device.27 Furthermore, the telescopic segment of the Y-stenting configuration increases the contact surface of the struts for better integration of the thrombus. The crossing Y-Solitaire technique might have other mechanical advantages, particularly for the removal of a saddle thrombus extending into multiple branches of a MCA bifurcation. The deployment of two SRs into different branches of a bifurcation might increase the strut/thrombus contact surface and enhance thrombus integration. Furthermore, the uniform spread of the retrieval force along the roots of the thrombus might contribute to its successful removal as one piece without fragmentation.

The crossing Y-Solitaire thrombectomy procedure has some potential disadvantages. The risk of endothelial or vessel wall injury is potentially higher during the simultaneous retrieval of two SRs than during the retrieval of a single SR. Supporting this hypothesis, Klisch et al reported a single case of vessel trauma out of 10 cases (10%) which were treated with the double Solitaire thrombectomy procedure.28 However, they performed a ‘parallel’ or ‘kissing’ Y-stenting technique in which two Solitaire SRs were deployed in a kissing configuration and simultaneously retrieved in parallel. No procedure-related complications other than reversible vasospasms occurred in our cases. Asymptomatic small petechial hemorrhages without space-occupying hemorrhage were observed on the 24 hours control CT examinations in two cases. However, the absence of any hemorrhage on the immediate postprocedural CT examinations in both cases indicates that the hemorrhage was related to reperfusion injury. In the crossing Y-stenting configuration, the proximal segment of the second stent is nested within the first deployed stent. So, crossing Y-Solitaire thrombectomy might be a less traumatic procedure than the parallel Y technique. Nonetheless, the crossing Y-Solitaire technique should be used only as a rescue treatment following the failure of standard thrombectomy therapies, considering its potential risk of vessel injury. A second disadvantage is that it is a relatively complex endovascular technique compared with standard thrombectomy treatments and requires a higher level of operator experience. This may limit the use of this technique. The increased cost of the procedure may be another disadvantage of crossing Y-Solitaire thrombectomy.

This study has some important limitations. First, the study population was too small to support strong conclusions. Second, it is a retrospective study. Therefore, there was no control group treated with alternative endovascular rescue treatment methods with which to compare the results.


Crossing Y-Solitaire thrombectomy seems to be an effective and safe alternative rescue technique to treat refractory MCA bifurcation occlusions that are refractory to standard thrombectomy procedures.


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  • Contributors All authors contributed to the manuscript through data collection, analysis, manuscript composition, and critical review.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent Not required.

  • Ethics approval Istanbul Medical School local ethics.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement N/A. There are no unpublished data.

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