In 45 patients with coronary bypass grafts, the breath-hold interval with a
nd that without preoxygenation was measured. Its effect on depiction of the
distal graft anastomosis at electron-beam tomography was evaluated. Preoxy
genation prolonged the breath-hold interval in most patients, thereby allow
ing greater anatomic coverage including more distal anastomoses. Preoxygena
tion may improve scanning of coronary bypass grafts and increase detectabil
ity of graft stenoses.