SUMMARY A new model of internal carotid artery embolism was developed using autologous clot. The clot was prepared by incubating blood at room temperature for 2 hours to inactivate plasminogen activators and then refrigerating it at 4° C for 22 hours. The purpose of the experiment was to devise a model of the intravascular lesion and not of stroke itself. The dog was chosen as the experimental animal since it has a maxillocarotid artery which permits collateral flow beyond proximal internal carotid artery occlusions. A volume of clot measuring 0.25 to 030 cc was sufficient to occlude the artery for 48 hours in 80% of the animals without causing major strokes. We have used this model to study clot radiolabeling and suggest it may also have application for evaluating thrombolytic drugs.Stroke Vol 10, No 4,1979 ALTHOUGH A NUMBER OF MODELS of cerebrovascular problems exist which have permitted the investigation of various aspects of the disease, 1 " 4 many are invasive and too "artificial" for the study of the detection and treatment of thromboembolic occlusions. We, therefore, initially developed a canine model of cervical carotid thrombosis which was used to study the fibrinogen uptake test (FUT).6 " 7 The current report concerns the development of a new canine model of internal carotid occlusion by emboli formed from autologous clot which, though it is prepared in vitro, consists only of blood components.Thrombi, the source of emboli, have been extensively evaluated, and the varying and complex structure of white arterial thrombi and red venous thrombi, as well as the inhomogeneity within each group, have been noted. 8 Attempts have been made to create blood clots closely mimicking "natural" thrombi by both in vivo 9 -10 and in vitro 111 * techniques. Simpler methods to produce an autologous clot with optimal strength using blood coagulated in a test tube have been tried but without complete success. 1617 The strength of a clot is based on a variety of factors involved in its production and destruction. Clot strength is related to clot retraction which is caused by the contraction phase of viscous metamorphosis of platelets. The amount of retraction is reflected by the volume of clot compared to the original volume of blood. 18 The firmness of a clot is described more specifically by its modulous of shear elasticity which can be measured elegantly by thromboelastography, 19 but grossly by simple observation. Retraction progresses over time but is counteracted by autolytic dissolution of the clot.The literature suggests that plasminogen activators which can lead to clot lysis are inactivated at room temperature, but that clot retraction is promoted by storage at 4° C. 20~22 The characteristics of undiluted, unaltered clotted whole blood have not been studied under various conditions of time and temperature.The dog is especially suited as the experimental animal for this model because of the presence of the maxillocarotid anastomosis ( fig. 1). This collateral vessel allows occlusion of the proximal internal...
