Effect of blood flow rate and donor vessel diameter on the patency of carotid venous bypass grafts in dogs

A saphenous vein graft was implanted from the right subclavian to the right common carotid artery in seven dogs (group I) and between the right and left common carotid arteries in another seven dogs (group II). The recipient artery was ligated proximally to augment blood flow through the graft. Immediately after the anastomoses were completed, the average blood flow through the graft was 32 +/- 25 mL/min in group I and 122 +/- 22 mL/min in group II. At sacrifice 30 days later, angiography showed that all grafts in group I were thrombosed, whereas six (87.5%) of seven grafts in group II were patent. These findings suggest that a larger donor vessel diameter and higher graft flow rates may improve patency in venous bypass grafts that are 3 to 5 mm in diameter.