Impact of the learning curve for endoscopic vein harvest on conduit quality and early graft patency

Abstract

Background: Recent studies have suggested that endoscopic vein harvest (EVH) compromises graft patency. To test whether the learning curve for EVH alters conduit integrity owing to increased trauma compared with an open harvest, we analyzed the quality and early patency of conduits procured by technicians with varying EVH experience.

Methods: During coronary artery bypass grafting, veins were harvested open (n=10) or by EVH (n=85) performed by experienced (>900 cases, >30/month) versus novice<100 cases, <3/month) technicians. Harvested conduits were imaged intraoperatively using optical coherence tomography and on day 5 to assess graft patency using computed tomographic angiography.

Results: Conduits from experienced (n=55) versus novice (n=30) harvesters had similar lengths (33 versus 34 cm) and harvest times (32.4 versus 31.8 minutes). Conduit injury was noted in both EVH groups with similar distribution among disruption of the adventitia (62%), intimal tears at branch points (23%), and intimal or medial dissections (15%), but the incidence of these injuries was less with experienced harvesters and rare in veins procured with an open technique. Overall, the rate of graft attrition was similar between the two EVH groups (6.45% versus 4.34% of grafts; p=0.552). However, vein grafts with at least 4 intimal or medial dissections showed significantly worse patency (67% versus 96% patency; p=0.05).

Conclusions: High-resolution imaging confirmed that technicians inexperienced with EVH are more likely to cause intimal and deep vessel injury to the saphenous vein graft, which increases graft failure risk. Endoscopic vein harvest remains the most common technique for conduit harvest, making efforts to better monitor the learning curve an important public health issue.

Trial registration: ClinicalTrials.gov NCT00481806.

Copyright © 2011 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Figures

Fig 1

Intraoperative examination of the saphenous vein (SV). On a sterile back table, veins were cannulated with a Y adapter to allow optical coherence tomography (OCT) images (A) to be obtained from an intraluminal 1F OCT wire (B) while gently distending the vein at 100 mm Hg pressure. As the imaging wire is pulled back from within the saphenous vein graft (SVG; C), it is localized by an infrared light emitted from its tip (arrow, D). Any detected abnormalities, such as a retained thrombus (E) with radial signal attenuation suggesting “red clot” (arrow, F), can then be exactly localized within the vein. (OR = operating room.)

Fig 2

Intimal and deep vessel injury after endoscopic vein harvesting. Evidence of injury noted by optical coherence tomography (A, C, E, G, I) was confirmed with registered histologic sections taken from the abnormal regions (B, D, F, H, J). Injury ranged in severity from being isolated to the intimal layer (A, C) to deeper vessel involvement such as a dissection into the medial layer (E) or disruption of the external elastic lamina (G, I). In each of these representative examples, the corresponding histologic section confirmed the diagnosis suggested by optical coherence tomography. (Hematoxylin and eosin stain; magnification ×10.)