Mechanical thrombectomy and intravascular imaging for cerebral venous sinus thrombosis: a preclinical model

OBJECTIVE Although the majority of patients with cerebral venous sinus thrombosis (CVST) will improve with anticoagulation therapy, a portion of patients will either present in a comatose state or continue to deteriorate clinically despite early anticoagulation. In these cases, along with treating the underlying thrombophilia, timely thrombolysis may be beneficial. Repurposed arterial thrombectomy devices may not perform as expected in the cerebral venous sinus, and there are currently no preclinical endovascular thrombectomy (EVT) models for CVST. Contrary to arterial stroke research, preclinical models utilized to test various endovascular techniques and devices are lacking. The purpose of this research was to develop a reliable preclinical animal model for the testing of endovascular strategies to treat CVST. METHODS Five consecutive male Yorkshire swine weighing 45 kg were utilized. Thrombosis of the superior sagittal sinus was induced with a bovine thrombin injection via a microcatheter under distal balloon occlusion for 15 minutes. Combined arterial injections and superselective sinus injections confirmed the extent of thrombosis. EVT was subsequently performed using a second-generation stent retriever, followed by intravascular optical coherence tomography (OCT) imaging to assess the luminal environment after thrombectomy. RESULTS Thrombosis of the superior sagittal sinus, EVT, and subsequent OCT imaging were technically successful in 4 of the 5 swine. Recanalization of the sinus with a second-generation stent retriever was successful after one attempt in 3 of 4 swine (75%), and 1 swine required two attempts. OCT imaging after thrombectomy revealed regions of residual sinus luminal thrombus despite complete angiographic recanalization. Thrombosed bridging cortical veins were also observed before draining into the sinus, along with patent cortical veins. CONCLUSIONS The authors describe a preclinical model to assess endovascular techniques and devices for the treatment of CVST. Repurposed devices from arterial stroke may not perform as expected, given the unique features of venous sinus thrombosis. Residual bridging cortical vein thrombus and residual sinus thrombus, visualized on intravascular OCT, may be present despite complete sinus recanalization on angiography, and this may be the etiology of the poor clinical outcome despite technical success. In the setting of bridging cortical vein thrombus after successful sinus thrombectomy, direct chemical thrombolysis may be warranted to dissolve the remaining clot. This model may be helpful in developing and testing a new generation of devices designed specifically for CVST treatment.