2g vitamin C (ascorbic acid) iv before cardiopulmonary bypass, 2 g vitamin C iv before removing the aortic clamp, 1g vitamin C iv 8 h after aortic clamp removal and every 8 h thereafter(2 times)

placebo (saline) iv before cardiopulmonary bypass, placebo before removing the aortic clamp, placebo iv 8 h after aortic clamp removal and every 8 h (2 times)

The vitamin C group will get high dose of intravenous vitamin C (ascorbic acid) before starting cardiopulmonary bypass, before removing aortic clamp and every 8 hours thereafter for additionaly 24 hours

Measuring the concentration of lactate before cardiopulmonary bypass, after aortic clamp removal, at ICU admission,then every 6 hours

The need for noradrenaline and other vasopressors (e.g. vasopresin) during the surgery and in the 24-hours after the end of the surgery

Measuring the concentration of glucose before cardiopulmonary bypass, after aortic clamp removal, at ICU admission, then every 6 hours