Cross-circulation thrombectomy with use of a stent retriever: A case report

Abstract

Introduction

The efficacy of the endovascular treatment of acute ischemic stroke has been substantiated by several recent randomized clinical trials. While intra-arterial therapy has significantly evolved in recent years, anatomic cerebrovascular variants and disease burden can present challenges to timely recanalization. We present the first reported case of anterior-to-posterior mechanical clot retrieval with use of a stent retriever.

Case description

A 53-year-old man presented with basilar artery thrombosis. Endovascular mechanical clot retrieval was performed. The typical, antegrade, access to the basilar artery thrombus was precluded by the findings of a hypoplastic left vertebral artery and an occluded proximal right vertebral artery. Given a number of factors including the patient’s worsening symptoms and the high morbidity and mortality associated with basilar stroke, cross-circulation—anterior-to-posterior—intra-arterial therapy was performed. Thrombectomy of the basilar thrombus was achieved via the right internal carotid artery and right posterior communicating artery.

Conclusion

To our knowledge, we report the first case of cross-circulation, anterior-to-posterior thrombectomy, with the use of a stent-retriever device. Cross-circulation stroke treatment may be beneficial in cases of proximal vessel occlusion or anatomical constraints. Larger studies will need to evaluate the safety and efficacy of these approaches.

Introduction

The etiology of acute ischemic stroke (AIS) is heterogeneous and its treatment requires specialized technical expertise.¹ Based on several recent landmark randomized trials, the endovascular treatment of AIS has become standard of care and has received the strongest recommendation—Class 1, Level of Evidence A—by the AHA/ASA.² Recanalization in these trials was achieved most commonly with use of a self-expanding retrievable stent.

Early mechanical recanalization can be challenged by various factors including stroke mechanism and cerebrovascular anatomy. To our knowledge, we present the first report of an anterior-to-posterior mechanical clot retrieval using a stent retriever.

Case

A 53-year-old man with a medical history notable for hypertension and Type 2 diabetes mellitus without any prior neurological history presented to the emergency department within three hours of developing lethargy, diplopia, and unsteady gait. He was administered intravenous tPA for AIS. While in the emergency room, the patient’s neurological condition abruptly deteriorated and he became unresponsive. Computed tomography (CT) angiogram revealed a basilar occlusion, a hypoplastic left vertebral artery, and a proximally occluded right vertebral artery. This was confirmed with catheter angiography (Figure 1). The patient was taken to the angio suite for attempted basilar clot removal.

Figure 1.

A hypoplastic left vertebral artery with a diminutive V4 segment. (a) Right deep cervical artery anastomosis reconstitutes the distal right vertebral artery. (b) Both injections show complete proximal basilar artery occlusion.

The hypoplastic left vertebral artery and the occluded right vertebral artery precluded conventional access to the basilar artery. A right internal carotid artery angiogram by way of a patent right posterior communicating artery (PCOM) revealed mid-basilar artery occlusion (Figure 2). A coaxial system consisting of a Neuron 070 guide catheter (Penumbra, Alameda, CA) and a Marksman microcatheter (ev3/Covidien, Irvine, California) was used to achieve microcatheterization of the basilar artery through the posterior communicating artery. A Solitaire FR 6 × 30 mm thrombectomy device (ev3/Covidien, Irvine, California) was successfully deployed within the basilar artery thrombus (Figure 2). The microcatheter and thrombectomy device were then withdrawn as a single unit, while continuous aspiration was applied to the guide catheter. Thrombus was not visualized on the stent and was presumed to have been aspirated through the guide catheter.

Figure 2.

A right internal carotid artery angiogram shows retrograde opacification of the basilar artery via the right posterior communicating artery (a). Microcatheter injection after catheterization through the basilar thrombus shows adequate position in the vertebrobasilar junction and redemonstration of occlusion (b). A Solitaire FR 6 × 30 mm thrombectomy device is deployed within the basilar artery thrombus (c).

Post-thrombectomy digital subtraction angiogram of the right internal carotid artery after a single pass with the thrombectomy device no longer showed retrograde, anterior-to-posterior, filling of the basilar artery consistent with competitive unopacified antegrade flow through the basilar artery from recanalization of the vessel (Figure 3, Image a). The right middle cerebral and anterior cerebral arteries and their distal vessels demonstrated normal opacification with no evidence of thromboembolic complication (Figure 3, Image a). A post-thrombectomy control digital subtraction angiogram performed via injection of the right deep cervical artery showed recanalization of the basilar artery with antegrade flow (Figure 3, Image b). Posterior circulation opacification was attenuated by vessel spasm at the right deep cervical artery origin.

Figure 3.

Post-thrombectomy right internal carotid artery injection shows minimal basilar opacification consistent with recanalization and restored antegrade flow (a). Post-thrombectomy right deep cervical artery injection shows recanalization of the basilar artery with antegrade flow (b).

Non-contrast head CT performed two days after thrombectomy confirmed right greater than left cerebellar infarcts. There was no evidence of any acute infarction in the anterior circulation to suggest embolization to new territory. Clinical exam did not suggest any embolization to new territory. There was no evidence of subarachnoid hemorrhage. The patient was monitored as an inpatient before being discharged home with close outpatient follow-up. At one-year follow-up he has residual mild hemiparesis and is functionally independent with a modified Rankin scale score of 1.

Discussion

This report describes a cross-circulation approach for mechanical basilar artery thrombectomy via the posterior communicating artery. To our knowledge this technique has not been previously reported.

Basilar artery occlusion is a devastating stroke syndrome, which can carry >80% mortality if untreated.³ Death or dependency remains high even with recanalization.⁴ Although excluded from the landmark endovascular ischemic stroke trials,⁵ the AHA/ASA considers it ‘reasonable’ to attempt basilar clot retrieval up to six hours from symptom onset. However, the therapeutic window for basilar occlusion is not well defined and many centers treat basilar thrombosis well beyond the six-hour mark.

A number of authors have reported their experience with cross-circulation therapy. Moret et al. first described the concept in the context of endovascular cerebral aneurysm treatment.⁶ Moret and colleagues described ‘retrograde’ aneurysm embolization of 10 cases, which would have otherwise been ‘impossible’ to treat. Many of these cases were performed with balloon assistance, and the balloon protection angle was optimal from a non-antegrade direction. In the treatment of basilar thrombosis, Liu et al. describe the use of the Penumbra aspiration system in an anterior-to-posterior fashion—left PCOM artery to basilar artery.⁷ Most recently, Kim et al. described a posterior-to-anterior—PCOM artery to left middle cerebral artery—clot retrieval with the use of a stent retriever.⁸ To our knowledge, our case is the first report of anterior-to-posterior basilar clot retrieval with the use of a stent retriever. In addition, there has been no report using a Solitaire FR stent retriever in a cross-circulation thrombectomy approach.

The need for a cross-circulation approach arises due to ‘antegrade’ vessel occlusion or other anatomical constraints. Variable radial force of stent retrievers allows for cross-circulation clot removal between vessels of notably different sizes, such as the basilar artery (on average 3.17 mm) and the PCOM artery (on average 1.5 mm).^9–11 Newer microwires, microcatheters, and clot-retrieval devices have presumably contributed to reducing complications associated with endovascular stroke treatment.¹² Vessel injury, distal embolization, and introducing thrombus into new arterial territories are risks associated with transcirculation endovascular therapy. Larger studies are needed to determine the safety of cross-circulation approaches.

Conclusion

In the budding era of endovascular acute stroke treatment, rapid recanalization of large vessel occlusion has proven fundamental to improved clinical outcomes. ‘Antegrade’ treatment of stroke may be thwarted by vessel occlusion or anatomical constraints. We have demonstrated the viability of an anterior-to-posterior mechanical clot retrieval of a basilar thrombus with the use of a stent retriever. Larger studies will need to verify the efficacy and safety of this approach.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.