HIGH-FLOW GAS INSUFFLATION TO FACILITATE MIDCABG - EFFECTS ON CORONARY ENDOTHELIUM

Background. During less invasive coronary bypass operations on the bea ting heart, as well as conventional operations using continuous warm c ardioplegia, a precise anastomosis is facilitated by a bloodless field . To maintain a clear field, many surgeons use high-now gas insufflati on. However, the potentially damaging effects of gas insufflation on c oronary endothelium have not been elucidated. Methods. Seven pigs unde rwent median sternotomy. Between two coronary occluders, an arteriotom y in the mid left anterior descending coronary artery (LAD) was perfor med. In the experimental group (n = 5), the operative field was kept c lear by exposing the arteriotomy to a catheter-directed stream of carb on dioxide at 15 L/min. In the control group (n = 2), the arteriotomy was left open to room air. After 20 minutes, the segments of LAD expos ed to carbon dioxide or room air, and the unexposed proximal LAD and r ight coronary artery, were processed, sectioned, and stained together. A murine anti-human tie-2 monoclonal antibody was used to identify en dothelium. Results. All unexposed LAD and right coronary artery segmen ts and all LAD segments exposed only to room air demonstrated normal, contiguous staining of endothelium with the murine anti-human tie-2 mo noclonal antibody. In contrast, all LAD segments exposed to high-now c arbon dioxide gas insufflation demonstrated near-complete loss of endo thelium, Conclusions. These data demonstrate that high-now carbon diox ide gas insufflation denudes the coronary artery of its endothelium. T his exposes blood elements to the subendothelium and promotes clotting , and endothelial loss may promote smooth muscle cell migration and pr oliferation. These events set the stage for early and late graft failu re. (Ann Thorac Surg 1998;66:1246-9) (C) 1998 by The Society of Thorac ic Surgeons.