Prototype percutaneous thrombolytic device:: Preclinical testing in subacute inferior vena caval thrombosis in a pig model

PURPOSE: To develop an animal model of subacute inferior vena caval (IVC) thrombosis and apply this model in evaluating the safety and efficacy of a prototype percutaneous thrombolytic device for restoring patency. MATERIALS AND METHODS: In 11 pigs, a stent with a ligature in the middle was placed in the IVC. Thrombin was injected to induce thrombosis. Hemostasis was achieved by using an occlusion balloon. The stent was ligated to prevent thrombus migration. Five to 8 days after thrombus induction, the ligature was broken and the stent fully deployed. In 10 animals, thrombectomy was performed by using the percutaneous thrombolytic device. A vena caval filter was inserted at the beginning of each declotting procedure. Thrombus removal percentage was estimated and pulmonary angiograms obtained to detect embolism before and after thrombectomy. The IVC was analyzed histologically. To determine thrombus composition, one animal was sacrificed without thrombectomy. Concerning procedural safety, failure of the stent delivery system, stent migration, and venous perforation due to balloon inflation and the stent placement or thrombectomy procedure were evaluated. RESULTS: Thrombus creation was successful in all animals. Fragmentation led to 75%-100% thrombus removal with flow restoration in all cases. There were no episodes of stent delivery failure, stent migration, or venous perforation. No significant pulmonary embolism was observed. in one case, a vessel dissection was identified at histologic examination. CONCLUSION: in this animal model of IVC thrombosis, the percutaneous thrombolytic device is effective and safe for clot removal.