 To establish the coronary sinus CS probe, the intubation of the coronary sinus is performed by means of a guide catheter, which can be used to take blood samples. After intubation of the coronary sinus, the coronary artery blood is taken from the guide catheter for the study as well as arterially via the underlying pressure catheter as well as peripheral venous over a horizontal venous catheter. The blood sampling does not take more than 1-2 minutes. 