Noninvasive Radioisotopic Technique for Detection of Platelet Deposition in Coronary Artery Bypass Grafts in Dogs and Its Reduction with Platelet Inhibitors

SUMMARY At 8 and 32 hours after saphenous vein bypass graft surgery 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 scin-tiphotos. In vitro images of the excised heart showed saphenous vein graft uptake confirming the in vivo image. 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 determina-tion 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. AORTOCORONARY BYPASS SURGERY with autologous saphenous vein grafts ' is used widely in patients with coronary artery disease. A major limita