Radiological and pathological changes in the sinus of an experimental arteriovenous fistula of the rat

The object of this study is to evaluate the radiological and pathological changes in the sinus of an experimental arteriovenous fistula of the rat. Twenty-five male Sprague-Dawley rats, including two control rats, were used for this study. A venous hypertension model in the transverse sinus was induced by means of anastomosis of a common carotid artery (CCA) to the ipsilateral external jugular vein (EJV). Rats were sacrificed 11 to 42 weeks after the procedure, then histopathological and immunohistopathological examinations were performed for the resected transverse sinus. Follow-up angiography was performed two to three weeks after the anastomosis in every case, and five months later in two rats. Patency of the anastomosed portion was confirmed in 12 of the 23 anastomosed rats. An ipsilateral carotid angiogram demonstrated a highflow arteriovenous (AV) shunt from the CCA to the sigmoid-to-transverse sinus and draining into the contralateral juglar vein. A contralateral angiogram displayed a steal phenomenon via the communicating artery. Histopathologically, the vein of the anastomosed portion and the transverse sinus were markedly dilated in with cases. There was a thickening the connecting tissue and a proliferation of fibroblast in four (50%) of the eight cases. Thrombus formation in the transverse sinus was found in one case. VEGF stained strongly in the endothelial hypertrophied area and in fibrous connective tissue around the transverse sinus compared to the control sinuses. Our results from this long-term observation of the radiological and pathological changes in the sinus exposed to hypertension resembled the clinical findings of a dural AV fistula.