Since selenium has demonstrated significant characteristics for a series of biochemical processes, for antioxidant activity and immune stimulation, this observational study should represent the effect of heart-lung-machine on selenium status of cardiac surgical patients undergoing coronary bypass surgery. It will be examined in (approximately 100) adult patients, under which 50 patients are operated conventionally (meaning with the use of heart-lung-machine). Another 50 patients are operated on beating heart without the use of heart-lung-machine (OPCAB = "off pump coronary artery bypass"). The allocation of individual patients in these two groups is done according to clinical criteria and is undertaken by the operating surgeon.

To produce two comparable groups of patients, the characteristics are recorded using EURO-Score; additionally the groups are "matched" (Matched-Pairs-Analysis).

All patients are operated by the same surgeon (senior physician Dr. A.K. Menon) under general anaesthesia through median sternotomy with elective or urgent indications.

After induction of anaesthesia, within the first hour after admission to the Intensive Care Unit (ICU) and every further morning in the ICU or Intermediate Care Station (IMC), 10ml blood are removed by a central venous catheter, allowing to measure blood selenium levels in whole blood by electrothermal atomic absorption spectrometry.

All blood draws will be held on vascular access, which is lying independently of the study participation for surgery or for intensive care treatment. The blood samples will be stored until completion of the study and its evaluation (up to 24 months) and are discarded afterwards. All data collected are recorded on a documentation sheet.

Inclusion Criteria:

• Coronary-3-vessel-disease
• Written informed consent
• Age of 18 years or older
• Study inclusion at the latest on the last evening before surgery

Exclusion Criteria:

• Other serious cardiac diagnosis (i.e. aneurysm, valvular-diseases)
• ischemic cardiomyopathy
• Patients not capable of consenting
• Pregnant or lactating women, women of child-bearing potential in whom pregnancy can not be excluded

Approximately 100 adult patients (male and female), capable of consenting, undergoing cardiac surgery.