Active_comparator: Cerebral Oxymetry Monitoring

The following procedures should be performed sequentially in the event of cerebral desaturation after 30 seconds:~1. The positioning of the head, the presence of facial plethora, and bad position of catheters should be corrected;~2. In case of arterial hypotension, the causal factors should be assessed and treated;~3. In the presence of arterial hypoxemia, the causal factors should be assessed and treated to maintain a PaO2 \> 150 mmHg;~4. In the presence of hypercapnia, adjust the ventilation parameters avoiding hyperventilation;~5. In the presence of anemia, the causal factors should be assessed, and the decision to undergo transfusion should also take into consideration the presence of tissue hypoperfusion;~6. In cases of SvO2 below 70% and signs of hemodynamic instability, optimize fluid replacement and ventricular global contractility;~7. Assess the increase of brain consumption of O2, avoiding the superficial level of anesthesia, hyperthermia, and tremors.

No_intervention: Control Group

Patients will be treated according to the attending anesthesiologist, without the monitoring of cerebral oximetry, but to maintain a heart rate between 70 - 100 bpm, lactate levels \<3 mmol/L and urine output\> 0.5mL/Kg/h. In case of arterial hypotension the causal factors should be assessed and treated; in case of SvO2 below 70% and signs of hemodynamic instability, optimize volume replacement and global ventricular contractility through inotropic agents (epinephrine, dobutamine or milrinone); in the presence of anemia (Hb \<6 to 7g/dL during CPB or Hb \<8g/dL in the pre-CPB or post-CPB period), the causal factors should be assessed and the decision to transfuse should also take into account the presence of hypoperfusion tissue (increased lactate, low SvO2, acidosis); in episodes of bradycardia with hemodynamic instability, atropine may be used.