 Prospective, randomized and controlled study involving 20 patients, 10 in each group. The de-airing time and the efficiency of the techniques will be assessed by trans-esophageal echocardiography TEE and trans-cranial echo-doppler monitoring TCD. The cardiologists analyzing the TEE recordings will be blinded to the de-airing technique used the recorded videos will be analyzed at the end of the study. The TCD monitoring will be done by on-line automatic recording of the micro embolic signals MES from the right and or left middle cerebral arteries and performed by single surgeon. The CO2 insufflation of the operating field will be performed according to manufacturers guide lines. During entire study course one type of extracorporeal perfusion system will be used.The study will be registered in the international database. A prior approval will be sought from the hospital ethical committee for the study. 