Objective: We describe a new technique to create an animal model of chronic venous thrombosis. The morphological and histological properties of the resulting thrombi are described.
Methods: Thirteen pigs underwent laparoscopic ligation of the infrarenal vena cava in combination with transfemoral thrombin infusion. After 1, 3, 6, 9, 12 and 15 days, respectively, two animals were killed and the thrombosed vein segments were explanted. After recording their weight and dimensions, the thrombi underwent histological examination by light microscopy.
Results: In all 13 cases, the procedure was completed laparoscopically and all 13 animals survived the procedure. While 12 pigs (92%) had an uneventful postoperative course, one animal died on the first postoperative night of an unknown cause. Autopsy revealed correct placing of the ligature with occlusive thrombosis of the inferior vena cava and the iliac veins in 12 animals, in one animal the ligature had been incorrectly placed around the origin of the right iliac vein with thrombosis limited to that vessel. Histological evaluation demonstrated mixed thrombi that showed increasing signs of organisation with advancing age.
Conclusions: Laparoscopic ligation of the infrarenal vena cava in combination with transfemoral thrombin infusion is a safe and reliable way to produce chronic venous thrombosis in an animal model. The resulting thrombi are comparable to human deep venous thrombosis in terms of extent, size and organisation process.