Comparison of blood flow and patency in arterial and vein grafts to basilar artery.

Blood flow and patency rates obtained by lingual to basilar artery anastomosis were compared with those obtained by saphenous vein bypass graft from the carotid to the basilar artey in two groups of ten dogs. Flow was measured by an electromagnetic technique while blood pressure and blood gases were monitored. Graft patency also was determined by angiography and histological examination. The arterial and venous grafts carried more than enough blood to maintain a normal flow (9.5 ml per minute) through the basilar system of dogs. Immediately after anastomosis, average flow through the vein grafts was 15.5 ml per minute (range 10 to 24 ml per minute). Six weeks later, average flow through the vein graft was 11.5 ml per minute and through the arterial graft 13 ml per minute. With induced hypertension, flow increased in the arterial grafts to an average of 26.2 ml per minute and in the vein grafts 24 ml per minute. Hypercarbia increased arterial graft flow to an average of 27.8 ml per minute and vein graft flow to 23.5 ml per minute. By angiography, graft patency was shown in only 80% of the grafts at one week and in 60% at six weeks postoperatively, even though all grafts were patent by flow and histological determinations. This failure of angiography represents a limitation of the radiographical resolution in millimeter-sized vessels.