Effect of proximal occlusion on anastomosis patency in dogs

This study compared the superficial temporal-middle cerebral artery (STA-MCA) anastomosis patency in animals with and without proximal embolic middle cerebral artery (MCA) occlusion. Sixteen dogs underwent STA-MCA bypass in association with silicone embolization of the MCA via an internal carotid injection. Animals re-explored 3 to 5 days postoperatively with evaluation of anastomosis patency by Evans blue injection and direct cutting of the STA demonstrated that 10 of 10 dogs with proximal MCA emboli had a patent STA-MCA anastomosis, whereas only 2 of 6 animals without an embolus lodged in the proximal middle cerebral artery had a patent connection. The likelihood of the anastomosis remaining open seems to be greatly influenced by the potential flow gradient between the extracranial and intracranial circulations (Neurosurgery, 5: 596--597, 1979).