Endoscopic Venous Harvesting by Inexperienced Operators Compromises Venous Graft Remodeling

Abstract

Endoscopic vein harvesting (EVH) is the standard of care for coronary artery bypass grafting (CABG) in the United States, but recent comparisons with open harvesting suggest that conduit quality and outcomes may be compromised in EVH. To test the hypothesis that problems with EVH may relate to its learning curve and conduit quality, we analyzed the quality and early function of conduits procured by technicians with varying experience in EVH. Experienced (more than 900 cases, n=55 patients) and novice (less than 100 cases, n=30 patients) technicians performed EVH during CABG. Subsequently, optical coherence tomography (OCT) was used to examine the conduits for vascular injury, with segments identified as injured being further examined for gene expression with an array of genes related to tissue injury. Conduit diameter was measured intra- and postoperatively (day 5 and 6 months, respectively) with OCT and computed tomographic angiography. Endoscopic vein harvesting by novice harvesters resulted in a greater number of discrete graft injuries and greater expression of tissue-injury genes than EVH done by experienced harvesters. Regression analysis revealed an association between shear stress and early dilation of engrafted vessels (positive remodeling) (R2=0.48, p<0.01). Injured veins showed blunted positive remodeling at 5 days after harvesting and a greater degree of late lumen loss at 6 months. Under normal conditions, intraluminal shear stress leads to positive remodeling of vein grafts during the first postoperative week. Injury to conduits, a frequent sequela of the learning curve for EVH, was a predictor of early graft failure and of blunted positive remodeling and greater negative remodeling of endoscopically harvested vein grafts. Given the current annual volume of cases in which EVH is used, rigorous monitoring of the learning curve for this procedure represents an important and unrecognized issue in public health.