Patterns of patency of 596 vein grafts up to seven years after aorta-coronary bypass. 
The long-term behavior of vein grafts and their effect on the native circulation were studied by examining 596 vein grafts in 343 patients at a mean follow-up of 15.4 months, range zero to 84 months.  Serial studies were performed on 27 patients with 38 grafts.  The over-all graft patency rate was 84 per cent, and the rate after more than 5 years was 89 per cent.  The patency rate in asymptomatic patients was 91 per cent compared with 81 per cent in the remainder.  The patency of grafts attached distal to total occlusions was 82 per cent (78/82).  The angle of origin of the grafts from the aorta did not appear to influence patency or the severity of intimal proliferative changes.  In 76 patients with 126 grafts, pre- and postoperative cineangiograms were compared, and changes in the graft and underlying coronary artery classified as Groups 1 to to 6: Group 1, patent graft, bidirectional flow in the grafted vessel, proximal lesion unchanged; Group 2, patent graft, bidirectional flow, proximal lesion progressed to occlusion locally; Group 3; patent graft, distal flow only, occlusion of lesion and segment between graft and lesion; Group 4, graft occluded, native artery unaltered; Group 5, graft occluded, native artery now occluded at lesion and region of anastomosis; Group 6, new distal lesion.  Results were as follows; Group 1, 58 per cent; Group 2, 21.2 per cent; Group 3, 5 per cent, Group 4, 12.5 per cent; Group 5, 2.5 per cent; and Group 6, 0.8 per cent.  Native coronary arteries undergoing closure (Group 2) had lesions 95 per cent or greater in 93 per cent of patients.  The rate of closure of ungrafted lesions was 2 per cent.  We believe these results encourage the continued used of vein bypass grafts.