• results of psychological examination [ Time Frame: 6 days, 3 and 12 months after surgery ] [ Designated as safety issue: Yes ]
  

• S-100B protein level in serum. NEECHAM delirium scale, stroke or other severe neurological impairment [ Time Frame: S-100B - 18 hours after surgery; Consciousnessand/or neurological impairment - wthin 6 days after surgery. ] [ Designated as safety issue: Yes ]
  

Patients assigned to the "sevoflurane" group will be anesthetized with inhaled sevoflurane (induction and conduction of general anesthesia) and empirically administered fentanyl und pancuronium. During the CPB, sevoflurane will be delivered via the oxygenator of the CPB-machine.

Patients assigned to the "propofol" group will be anesthetized with continuous propofol infusion and empirically administered fentanyl and pancuronium.

The level of anesthesia will be monitored with BIS (bi-spectral index) - desirable level of 40 - 60.

Following preoperative data will be recorded: age, years of school education, NYHA-class, LVEF by TTE, comorbidities, glucosylated hemoglobin in patients with diabetes, non-invasive arterial blood pressure the day before the operation, smoked cigarettes, alcohol abuse.

Recorded data from operation: type of surgery, CBP duration, aortic clamp duration, duration of arterial hypotension (MAP < 60 mmHg) on CPB or SAP < 90 after CPB, the lowest perfusion gradient (MAP-CVP), the lowest pO2 in arterial blood and lowest blood oxygen saturation, lowest and average brain blood saturation (measured by INVOS), steroid dosis, aprotinin dosis, mannitol dosis on CPB, epiaortic echocardiography for aortic clamping, TEE before weaning from CPB with evaluation of deaeration of the left ventricle, highest serum glucose level, highest oesophageal temperature.

Data collected after operation: time to tracheal extubation, doses of catecholamines, consciousness disorders, CRP, S-100b protein, glucose level, core temperature, ICU stay, stay at the surgery department, hospital stay.

The patients will undergo a psychological examination four times: before the operation, before discharge from hospital (usually 4-6 days after the operation), 3 and 12 months after the operation. The psychological test for evaluating the cognitive modalities will include:

1. verbal learning - the Rey's AVLT test
2. direct verbal memory - number repeating attempt from the WAIS-R/PL test
3. direct nonverbal memory - Memory Test of Geometric Figures by Benton
4. operating memory test - TMT test
5. the cognitive interference test - a modified Stroop test
6. verbal fluence - according to the Boston Test of Aphasia
7. concentration and work effectiveness - by the Number Symbol test by Wechsler.
8. mood - Beck's depression scale
9. NEECHAM Delirium Scale - during the first 24-36 hours after surgery
10. the Gough's Adjective Test will be performed with in-house relatives of the patient for evaluation the eventual emotional and eventual personality changes

Neurological examination will be performed before and 6 days after surgery.