COMPARISON OF FLOW CAPACITIES OF ARTERIAL AND VENOUS GRAFTS FOR CORONARY-ARTERY BYPASS-GRAFTING - EVALUATION WITH EXERCISE TL-201 SINGLE-PHOTON EMISSION TOMOGRAPHY

Stress thallium-201 tomography was :performed to compare the flow capa cities of arterial and saphenous vein grafts in patients with coronary artery by-pass grafting (CABG). One hundred and seven consecutive pat ients (95 male and 12 female; mean age 58+/-9.1 years) underwent exerc ise-redistribution (201)T1 myocardial single-photon emission tomograph y 4-5 weeks after CABG, When a reversible perfusion defect was present in the area covered by a patent bypass graft, the flow capacity of th e graft was defined as insufficient. Of all 285 grafts, 211 were consi dered as complete bypass. Reversible perfusion defects were present in 29 (27%) of 108 myocardial areas supplied by patent arterial grafts b ut in only 5 (5%) of 103 myocardial areas supplied by patent saphenous vein grafts (P<0.0001). In the LAD area reversible defects were obser ved in 22 of 82 areas covered by arterial grafts, in contrast to only 1 of 29 areas covered by venous grafts (P<0.01); in the RCA area rever sible defects were observed in 7 of 17 and 4 of 41 areas respectively (P<0.01), There was no difference between the native coronary artery s tenosis bypassed by patent arterial and venous grafts (88%+/-12% vs 86 %+/-14% respectively, P=0.27). In conclusion, flow capacities during p eak myocardial demand were more frequently insufficient in arterial by pass grafts than in saphenous vein grafts.