Venous stenosis model induced by local mechanical injury with the presence of surgical arteriovenous fistula in swine

Objective: To evaluate a new animal model of venous stenosis induced by local mechanical injury with the presence of surgical arteriovenous fistula (AVF). Methods: Twelve arteriovenous (AV) fistulae were surgically formed between the carotid artery and internal jugular vein in six adult pigs, one on each side of the neck. Direct mechanical injury was made by crush injury with fingers or forceps to the jugular vein at the sites 1-2 cm above and below the AV anastomosis. Angiographic follow-up was performed at 3 and 6 weeks, and the animals were sacrificed. Fistulae and injured veins were harvested for histopathology. Results: At angiography six AV anastomoses were patent without stenosis, five were stenosed and one had occluded. Eleven of twelve venous injury sites with open AV anastomosis and six of ten venous injury sites with AV anastomotic stenoses developed greater than 50% diameter stenosis. Dilation was found in the non-injury segment of eight jugular veins. Stenoses were caused by neo-intimal hyperplasia as seen on histologic examination. Conclusions: Neo-intimal venous stenosis can be induced by creation of a surgical AV fistula and local venous mechanical injury. This model may be used to study methods to reduce or inhibit neo-intimal hyperplasia, with particular reference to venous stenoses that occur in arteriovenous shunts created for dialysis access