The present study included 60 pediatric patients undergoing repair of congenital heart defects including cyanotic and acyanotic patients, with average age of 2-6 y and body weight of 8-20kg. Anesthetic preconditioning refers to the phenomenon whereby exposure of the heart to a volatile anesthetic before myocardial ischemia results in protection against the deleterious effects of myocardial ischemia and reperfusion. Compared with control conditions, this protection manifests as an improvement at the level of different variables such as infarct size and contractile function, but also coronary flow and free radical release at reperfusion.Several studies on sevoflurane and isoflurane have demonstrated their clinical cardioprotective effect in patients undergoing open heart surgeries which was evidenced by lower release of biochemical markers of myocardial damage, better systolic function and lower ICU stay.