Severe impairment of graft flow without electrocardiographic changes during coronary artery bypass grafting.

Early graft occlusion after coronary artery bypass grafting may have deleterious consequences. We routinely use transit-time flowmetry after termination of cardiopulmonary bypass, and we report five cases of early graft failure detected by the flowmeter. Electrocardiographic (ECG) changes were seen in only one of these five cases, and none of the patients had low cardiac output or other signs of graft failure at the end of the operation. The cause of graft failure was tagging in one case, rotation of internal mammary artery grafts in two and kinking of vein grafts in two cases. All errors were corrected, and control flowmetry showed normal flow rates after correction. Flowmetry takes less than 10 min, even with multiple bypass grafts. Based on our results, we advocate routine quality control with flowmetry after termination of cardiopulmonary bypass, since ECG changes are insufficient as checks of flow in bypass grafts.