NON-INVASIVE RADIOISOTOPIC TECHNIQUE FOR DETECTION OF PLATELET DEPOSITION IN CORONARY-ARTERY BYPASS GRAFTS IN DOGS AND ITS REDUCTION WITH PLATELET INHIBITORS

At 8 and 32 hours after saphenous vein bypass graft in six dogs, in vivo images of the graft were obtained with a gamma camera after intravenous injection, 2 hours postoperatively, of autologous platelets labeled with indium-111. Platelet deposition in the grafts could be imaged in vivo from the scintiphotos. In vitro determination of radioactivity in the graft averaged 17 ± 14 times greater than in blood and 33 ± 26 times greater than in the lung. Under identical conditions, in eight dogs treated with dipyridamole (55 mg/day) plus aspirin (325 mg/day), the grafts appeared to have considerably less platelet deposition as estimated by imaging. In vitro determination of radioactivity in the graft averaged 5 ± 2 times greater than in blood and 8 ± 4 times greater than in the lung (p<0.01). This noninvasive technique may be a promising tool for a better understanding of the role played by platelets in the process of occlusion of saphenous vein bypass grafts in man and its prevention with platelet inhibitors.