<qa>  How many patients will receive norepinephrine in the dose needed to maintain pre24 patients scheduled for coronary artery bypass surgery will be included and randomized to receive either norepinephrine in the dose needed to maintain pre-anesthesia blood pressure or to a control group and receive norepinephrine only if mean arterial pressure decreases below 60 mmHg. Equal anesthesia in both groups will be monitored. No fluids will be infused. 