Stroke outcome determination with a prefabricated fibrin-rich macroclot ina thromboembolic rat middle cerebral artery occlusion model

The main disadvantage of current thromboembolic stroke models is non-unifor mity of location and size of the infarcts. In the present study, standard-s ized autologous macroclots were formed by means of polyethylene tubings wit h defined inner diameters (280, 360 or 400 mu m), and a single macroclot wa s injected into the internal carotid artery (ICA) of rats. Angiograms revea led that occlusions of the ipsilateral ICA at the origin of the middle cere bral artery (MCA) or occlusions of the distal MCA were produced in 47 out o f 50 animals embolized with macroclots of different size. In increasing the diameters of the macroclots from 280 to 400 mu m, occlusions of the ICA in creased at the expense of having fewer distal MCA occlusions. Increasing cl ot diameter also correlated with neurological impairment. Only cortical and striatothalamic subcortical regions of the MCA territory ipsilateral to cl ot injection showed infarcted tissue at 60 min-48 h after embolization as d etermined histologically and by magnetic resonance imaging. Infarct volume did not depend on clot diameter. Injected clots were prone to rt-PA thrombo lysis (20 mg/kg iv over 45 min). This model of thromboembolic ischaemia see ms well-suited to testing the efficacy and safety of new therapeutic strate gies. (C) Harcourt Publishers Ltd 1999.