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Publication Dielectric profile of blood clots to inform ischemic stroke treatments(IEEE, 2020-07-20) Santorelli, Adam; Fitzgerald, Seán; Douglas, Andrew; Doyle, Karen M.; O’Halloran, MartinPlatelet and fibrin-rich blood clots can respond differently to red blood cell rich clots during ischemic stroke treatment, which includes thrombolysis and mechanical thrombectomy. Currently, there is no accurate way to identify the type of clot in advance of treatment. If the type of blood clot can be identified, the optimum clot removal process can be chosen and patient outcomes can be improved. In this paper we fabricate physiologically relevant blood clot analogues from human blood, that cover a range of red blood cell, fibrin, and platelet concentrations. We characterize the dielectric profile of these formed clots using an open-ended coaxial probe method across a wide frequency range. After the dielectric measurements are completed, histology on each blood clot is performed to determine the concentration of red blood cells present. In total, 32 unique blood clots were measured. With this completed analysis, we investigate the correlation between the dielectric properties across this frequency range and the red blood cell count of the formed blood clots. Furthermore, we develop a model to predict whether an unknown blood clot can be categorized as red blood cell rich or platelet and fibrin-rich based solely on the measured dielectric properties.Publication Fatty acid binding protein expression in clots retrieved by mechanical thrombectomy from patients with acute ischaemic stroke(Sage Publications, 2019-05-22) Mereuta, Oana Madalina; Fitzgerald, Seán; Douglas, Andrew; Rossi, Rosanna; Silva Santos, Andreia M.; Pandit, Abhay; Thornton, John; O'Hare, Alan; Power, Sarah; Brennan, Paul; Rentzos, Alexandros; Tatlisumak, Turgut; Gunnarsson, Thorsteinn; Davidson, Maria; Brederlau, Anke; Allardt, Arne; Brinjikji, Waleed; Kallmes, David F.; Doyle, Karen M.; European Stroke Journal 4 (1 S); Science Foundation IrelandIntroduction: Lipid accumulation and inflammation are considered hallmarks of the unstable atherosclerotic plaque. In particular, adipocyte fatty acid binding protein (FABP4) expression within the plaque is associated with its progression and vulnerability. The aim of this study was to investigate the histopathology of thrombi collected from acute ischaemic stroke patients who underwent mechanical thrombectomy focusing on the presence of FABP4 and other atherosclerotic plaque components, including collagen and dystrophic calcification. Methods: 250 mechanically extracted thrombi were collected from three partner hospitals: Beaumont Hospital (Dublin, Ireland), Sahlgrenska University Hospital (Gothenburg, Sweden) and Mayo Clinic (Rochester, Minnesota, USA). Clots were immediately formalin-fixed and embedded in paraffin. 3-µm thickness serial sections were cut and stained with Martius Scarlett Blue to identify erythrocytes, fibrin, white blood cells and platelets/other. Masson s and von Kossa stains were performed to identify collagen and calcification, respectively. The expression of FABP4 was assessed by immunofluorescence. Results: FABP4 expression by adipocytes was confirmed in eight of 250 clots (3.2%). Adipocytes represented the main component in one white clot. Collagen was associated in two cases whereas von Kossa staining showed calcification in one case. Conclusions: The expression of potentially atherogenic components in these clots suggests that they may have originated from large vessel occlusions. Further studies are required to confirm the atherosclerotic aetiology. Our findings have implications for neurointervention and therapeutic strategies to reduce atherosclerotic plaque progression and stroke recurrence.Publication Does bridging therapy in mechanical thrombectomy increase recanalization rates in ischemic stroke patients affected by acute large vessel occlusion?(SAGE Publications, 2019-05-22) Silva Santos, Andreia M.; Rossi, Rosanna; Pandit, Abhay; Fitzgerald, Seán; Mereuta, Oana Madalina; Douglas, Andrew; Thornton, John; Brennan, Paul; Power, Sarah; O’Hare, Alan; Rentzos, Alexandros; Ceder, Erik; Tatlisumak, Turgut; Jood, Katarina; Redfors, Petra; Nordanstig, Annika; Duffy, Sharon; Gilvarry, Michael; McCarthy, Ray; Doyle, Karen M.; Science Foundation Ireland; CerenovusBoth intravenous thrombolysis with tissue plasminogen activator (IV-rtPA) and mechanical thrombectomy (MT) increase recanalization rates. We assessed if bridging-therapy (the concomitant use of rtPA and MT) could increase the recanalization rates and reduce the number of procedural passes in patients suffering from acute ischemic stroke (AIS) when compared to MT alone. Analysis of type of device used, stentriever or aspiration catheter, is also reported. 334 mechanically extracted thrombi were collected from two partner hospitals: Beaumont (Dublin) and Sahlgrenska (Gothenburg). 158 patients (47.3%) were treated with bridging-therapy, while 176 (52.7%) underwent MT alone. Recanalization rate was defined by using the modified Thrombolysis In Cerebral Infarction (mTICI) score. Non-parametric Kruskal-Wallis test was used for statistical analysis. Bridging-therapy reduced the total number of passes to remove the clot (mean for MT+rtPA=2.27±2.10, MT alone=2.63±1.88, H1=4.376, p=0.036*). Analysing the device, rtPA lowered the overall number of passes using stentriever devices (mean for MT+rtPA=1.57±1.12, MT alone=2.36±1.48, H1=8.303, p=0.004*), but not for aspiration (mean for MT+rt-PA=1.78±1.22, MT alone=2.03±1.47, for H1=0.795, p=0.372). Also, when using both devices no significant reduction of number of passes was observed (mean for MT+rtPA=3.29±2.90, MT alone=3.83±2.20, H1=3.027, p=0.082). There was no significant effect on final mTICI score using bridging-therapy when compared to MT alone (H1=1.163, p=0.281). This small study suggests that bridging-therapy lowers the number of procedural passes in MT procedures, specifically when using stentriever devices. However, this did not have a significant effect on final mTICI score. Funding: Science Foundation Ireland (Grant Number 13/RC/2073) and Cerenovus.Publication The impact of occlusion location and bridging therapy in patients affected by acute ischemic stroke in determining the total number of passes required to remove the clot and the final revascularization outcome(WFITN (World Federation of Interventional and Therapeutic Neuroradiology), 2019-10-21) Rossi, Rosanna; Fitzgerald, Seán; Mereuta, Oana Madalina; Douglas, Andrew; Pandit, Abhay; Szikora, István; Tsivgoulis, Georgios; Psychogios, Klearchos; Murphy, Blathnaid; Brennan, Paul; Power, Sarah; O'Hare, Alan; Thornton, John; Rentzos, Alexandros; Tatlisumak, Turgut; Doyle, Karen M.; Science Foundation Ireland; CerenovusPurpose Our purpose was to assess the impact of occlusion location in patients suffering from Acute Ischemic Stroke (AIS) on the total number of passes (attempts) necessary to retrieve the clot and on final revascularization outcome. Moreover, we analysed the impact of bridging-therapy, i.e. the concomitant use of IV tPA (intravenous tissue plasminogen activator) and mechanical thrombectomy (MT) on the different categories of occlusion locations. Methods 550 mechanically extracted thrombi were collected from four partner hospitals: Beaumont (Dublin) Sahlgrenska (Gothenburg), National Institute of Clinical Neurosciences (Budapest) and Metropolitan Hospital (Piraeus). In the vast majority of the cases (311 patients, 56.5%) the thrombus was located in the Middle Cerebral Artery (MCA), followed by Carotid Terminus/Internal Carotid Artery (ICA) in 89 cases (16.2%) and by vertebral/basilar artery (45 patients, 8.2%). In 65 cases (11.8%) a tandem occlusion, i.e. the occlusion of both ICA and MCA was found, while a dual occlusion occurred in 26 cases (4.7%). 248 patients (45.1%) underwent bridging-therapy, while 291 patients (52.9%) were treated with MT alone. For 11 patients (2%) we have no information whether tPA was administered or not. Recanalization rate was defined by using the modified Thrombolysis In Cerebral Infarction (mTICI) score. Non-parametric Kruskal-Wallis test using IBM SPSS-25 software was used for statistical analysis. Results Occlusion location had a significant impact on the total number of passes required to retrieve the clot as well as on final revascularization outcome. The cases with tandem and dual occlusion showed higher number of procedural passes and lower percentage of complete revascularizations (mTICI=3, Table 1). Bridging-therapy did not significantly reduce the total number of passes or improve the recanalization rates for patients with singular occlusion. On the other hand, bridging-therapy significantly lowered the total number of passes to remove the clot in patients with dual and tandem occlusion (N=87, mean for MT+tPA= 2.63±1.73, MT alone=3.80±2.14, H1=7.608, p=0.006*), but had no statistically significant effect on the final mTICI score (N=87, H1=0.266, p=0.606). Conclusion This study suggests that occlusion location significantly influences the total number of procedural passes in MT procedures as well as the final revascularization outcome. Furthermore, bridging-therapy lowers the number of procedural passes in cases of tandem and dual occlusion without having significant effect on final mTICI score. Funding: Science Foundation Ireland (Grant Number 13/RC/2073) and Cerenovus.