Is electrocautery safe for internal mammary artery (IMA) mobilization? A study using scanning electron microscopy (SEM).

Being the graft of choice, the internal mammary artery (IMA) is increasingly used for coronary artery bypass grafting. Presently, electrocautery is liberally used to mobilize both IMAs. Preservation of IMA flow surface was evaluated by scanning electron microscopy (SEM) after mobilization with either sharp dissection or electrocautery in five clinical patients undergoing coronary artery bypass surgery. Major side branches were secured with metallic clips. Specimens for SEM were harvested after heparinization but before institution of cardiopulmonary bypass from the terminal branches of both IMAs after they had been skeletonized with either mobilization method. When mobilization of the IMA was performed as a pedicle, the flow surface was well preserved in both groups. However, if a contact of the electrocautery blade with the wall of the IMA or with a metallic clip parallell to the wall was allowed, a clearly visible zone of endothelial damage, sometimes associated with mural trombus formation was observed. In conclusion, caution is needed with electrocautery. Thermal injuries of the IMA may remain undetected during surgery and cause graft occlusion later.