Flow in coronary artery bypass grafts to totally and partially occluded left anterior descending coronary arteries.

Flow was determined by electromagnetic flowmeter in vein bypass grafts in 20 patients with a totally occluded left anterior descending (LAD) coronary artery and on 61 patients with a partially occluded LAD. The median flow in LAD grafts was 14.5 ml/min with total LAD occlusion, and 40 ml/min with partial LAD occlusion (p less than 0.001). In cases of total LAD occlusion, the presence of mild or moderate anteroseptal wall dysfunction was associated with more satisfactory flow than was the case with severe anteroseptal wall dysfunction (p less than 0.02). Flows over 25 ml/min were found only when the LAD distal to total occlusion was 1.5 mm or greater. Unsatisfactory flows were consistently found with total LAD occlusion, poor ventricular function, and a distal LAD less than 1.5 mm. Repeat catheterizations to determine an unsatisfactory patency rate under these conditions would be necessary to alter our policy of grafting all suitable vessels beyond a total occlusion.