A carotid stenosis model in canines.

A carotid stenosis model was developed in canines in order to study the effects of systemic blood pressure and hemodilution on cerebrovascular perfusion and metabolism during cardiopulmonary bypass in the setting of significant coexistent inflow stenosis. Under general anesthesia, through a low midline neck incision, the carotid sheath was entered and the carotid artery was isolated and retracted medially. The vertebral artery could be identified posterolaterally. After ligating the vertebral artery with a 00 silk tie, carotid stenosis was created by tying bilateral carotid arteries over an 18-gauge needle using a 00 silk tie. The needle was then removed, leaving a tight stenosis. To determine the degree of stenosis, arteriograms were performed, revealing high-grade lesions of greater than 90% stenosis in the carotid arteries and absence of flow through the vertebral arteries. Cerebral blood flow studies during cardiopulmonary bypass (CPB) were performed, revealing a significant decline. Carotid arteries were harvested at the conclusion of the experiments, revealing tight lesions on direct inspection. The mean gradient measured across stenotic segments was >25 mm Hg. In conclusion, a carotid stenosis model can be created successfully in dogs by ligating the vertebral arteries bilaterally and simply using the shaft of a needle to standardize the lumen size of the carotid arteries. We found the diameter of an 18-gauge needle sufficient to produce stenoses of greater than 90% as evidenced by arteriograms.