Displacement of the beating heart induces an immediate and sustained increase in myocardial reactive oxygen species.

BACKGROUND Heart manipulation and displacement are common maneuvers during beating heart surgery to expose coronary arteries for revascularization. Effects of heart displacement on free radical generation, reactive oxygen species (ROS) have not been previously described. METHODS AND RESULTS Seven adult male dogs were anesthetized, a left lateral thoracotomy performed to expose the heart, and the coronary sinus cannulated for ROS sampling during different manipulation protocols: (1) heart in normal position; (2) 90 degree manual heart displacement; (3) Trendelenburg position while the heart displaced 90 degrees and (4) return heart to normal resting anatomical position and plus the operating table returned to horizontal. Heart displacement followed by anatomical re-positioning significantly increased the ROS signal as measured by EPR (50-fold compared with control values; p<0.01). CONCLUSION Trendelenburg positioning and/or repositioning the heart during cardiac surgery may induce acute reperfusion injury and increase ROS.