Abstract
Background: Combined intravenous thrombolysis and mechanical thrombectomy (IVT-MT) is a common treatment in acute ischaemic stroke, however the interaction between IVT and MT from a physiological standpoint is poorly understood. In this pilot study, we conduct numerical simulations of combined IVT-MT with various idealised stent retriever configurations to evaluate performance in terms of complete recanalisation times and lysis patterns. Methods: A 3D patient-specific geometry of a terminal internal carotid artery with anterior and middle cerebral arteries is reconstructed, and a thrombus is artificially implanted in the MCA branch. Various idealised stent retriever configurations are implemented by varying stent diameter and stent placement, and a configuration without a stent retriever provides a baseline for comparison. A previously validated multi-level model of thrombolysis is used, which incorporates blood flow, drug transport, and fibrinolytic reactions within a fibrin thrombus. Results: Fastest total recanalisation was achieved in the thrombus without a stent retriever, with lysis times increasing with stent retriever diameter. Two mechanisms of clot lysis were established: axial and radial permeation. Axial permeation from the clot front was the primary mechanism of lysis in all configurations, as it facilitated increased protein binding with fibrin fibres. Introducing a stent retriever channel allowed for radial permeation, which occurred at the fluid-thrombus interface, although lysis was much slower in the radial direction because of weaker secondary velocities. Conclusions: Numerical models can be used to better understand the complex physiological relationship between IVT and MT. Two different mechanisms of lysis were established, providing a basis towards improving the efficacy of combined treatments.
Highlights
Acute ischaemic stroke (AIS) is the second most common cause of mortality worldwide, and is associated with significant morbidity in survivors [1]
Meta-analyses, including the larger thrombectomy randomised trials [2] and another based on studies during the last 3 years [3], found that compared to mechanical thrombectomy (MT) alone, intravenous thrombolysis (IVT) prior to MT led to better clinical outcomes, lower mortality, and higher rates of successful recanalisation
Thrombolysis can result in intracranial haemorrhage (ICH), with associated morbidity and mortality, there was no significant difference in ICH rate between thrombectomy alone and combination therapy [2,3,5]
Summary
Acute ischaemic stroke (AIS) is the second most common cause of mortality worldwide, and is associated with significant morbidity in survivors [1]. Meta-analyses, including the larger thrombectomy randomised trials [2] and another based on studies during the last 3 years [3], found that compared to MT alone, IVT prior to MT led to better clinical outcomes, lower mortality, and higher rates of successful recanalisation. Combined intravenous thrombolysis and mechanical thrombectomy (IVTMT) is a common treatment in acute ischaemic stroke, the interaction between IVT and MT from a physiological standpoint is poorly understood. In this pilot study, we conduct numerical simulations of combined IVT-MT with various idealised stent retriever configurations to evaluate performance in terms of complete recanalisation times and lysis patterns. Two different mechanisms of lysis were established, providing a basis towards improving the efficacy of combined treatments
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