Introduction Since Beck's1 first attempt at revascularization of the myocardium in patients with coronary stenosis or occlusion, many types of operative procedures have been tried. They can be broadly classified as (a) indirect or palliative, and (b) direct or reconstructive. Table 1 summarizes the important ones. There is controversy about the results of indirect operations. Because of the lack of an accurate method of demonstrating increased myocardial flow, it is difficult to make a critical evaluation of these procedures in clinical cases. Since ideally no procedure should be better than one restoring normal flow by removing or bypassing the block, much interest has recently been focused on the direct operations. Review of the Literature Anatomical Studies. —In his important injection studies of postmortem hearts, Blumgart2 reported that the obstructing lesions in the arteries were segmental in nature and generally localized in the main stems within 5 cm. of