Eight-year follow-up of experimental carotid-middle cerebral and carotid-basilar arterial bypass grafts and anastomoses.

Fifty-one dogs were operated upon, and various microvascular bypass grafts and anastomoses were completed. Seventeen of these dogs were followed for 5 to 8 years. Of these, three had a carotid-middle cerebral arterial bypass graft, five had a carotid-basilar arterial bypass graft, five had a lingual-basilar anastomosis, and four had a sublingual-basilar anastomosis. Postoperative carotid angiograms showed patent grafts and anastomoses in all of the dogs. Except for slight to moderate enlargement of the donor artery in the lingual and sublingual-basilar anastomoses or minor irregularities in the carotid-middle cerebral and carotid-basilar arterial bypass grafts, no significant changes were noted. In five dogs with lingual-basilar anastomoses in which both internal carotid arteries were ligated, the mean blood flow of the lingual artery was increased to 1.1 to 2.4 times normal. This study shows that, when experimental arterial bypass grafts and anastomoses remain patent for a few weeks after the operation, they stay patent for years, and, depending on the need, the blood flow through the anastomosis may increase.