Revolution in acute ischaemic stroke care: a practical guide to mechanical thrombectomy

Abstract

Rapid, safe and effective arterial recanalisation to restore blood flow and improve functional outcome remains the primary goal of hyperacute ischaemic stroke management. The benefit of intravenous thrombolysis with recombinant tissue-type plasminogen activator for patients with severe stroke due to large artery occlusion is limited; early recanalisation is generally less than 30% for carotid, proximal middle cerebral artery or basilar artery occlusion. Since November 2014, nine positive randomised controlled trials of mechanical thrombectomy for large vessel occlusion in the anterior circulation have led to a revolution in the care of patients with acute ischaemic stroke. Its efficacy is unmatched by any previous therapy in stroke medicine, with a number needed to treat of less than 3 for improved functional outcome. With effectiveness shown beyond any reasonable doubt, the key challenge now is how to implement accessible, safe and effective mechanical thrombectomy services. This review aims to provide neurologists and other stroke physicians with a summary of the evidence base, a discussion of practical aspects of delivering the treatment and future challenges. We aim to give guidance on some of the areas not clearly described in the clinical trials (based on evidence where available, but if not, on our own experience and practice) and highlight areas of uncertainty requiring further research.

Keywords: mechanical; stroke; thrombectomy; thrombolysis.

Figure 1

A range of different clot types, which have different physical properties, potentially requiring a range of thrombectomy techniques. These are experimental clot analogues, primarily from ovine blood. Image provided courtesy Neuravi.

Figure 2

Freshly removed clot enclosed in a stent retriever device.

Figure 3

Plain CT scan of head (a) and prethrombectomy (b) and post-thrombectomy (c) digital subtraction angiograms in a 49-year-old woman with sudden onset left hemiparesis and confusion. Plain CT scan of head shows hyperdense clot in the right middle cerebral artery (red arrow) and early perisylvian loss of grey–white matter differentiation. Prethrombectomy digital subtraction angiogram shows occluded right proximal middle cerebral artery (blue arrow). The catheter is visible passing through the occlusion. Post-procedure imaging shows good filling of all middle cerebral artery branches (yellow arrow). There was complete resolution of neurological signs and symptoms following aspiration thrombectomy.

Figure 4

Plain CT scan of head (a) and prethrombectomy (b) and post-thrombectomy (c, e, f) digital subtraction angiograms in a 58-year-old man with a short history of visual symptoms and vertigo followed by a rapid drop in conscious level. Plain CT scan of head (a) shows thrombus in the basilar artery (red arrow) with complex plaque at the vertebral artery origin, confirmed on digital subtraction angiography (b). Following successful thrombectomy (c), with removal of a large cast of thrombus (d) by aspiration, a stent was deployed across the unstable stenotic plaque at the vertebral artery origin (blue arrows, e and f). Basilar thrombi can often be removed in bulk like this, possibly because of their physical composition.

Figure 5

Plain CT scan of head (a) and prethrombectomy (b, c), during thrombectomy (d, e, f) and post-thrombectomy (g, h) digital subtraction angiogram images in a 61-year-old man who presented with a 10 min seizure, followed by left-sided weakness and neglect. Plain CT scan of head shows hyperdense thrombus in the right middle cerebral artery (red arrow, a) with angiogram identifying a critical stenosis of the internal carotid artery origin (blue arrow, b). We performed middle cerebral artery thrombectomy using stent retriever technique (e and f). An internal carotid artery stent was inserted (green arrow, d) complicated by an iatrogenic dissection (yellow arrow, e) necessitating stenting (purple arrow, h).