 Former studies revealed a distinct pattern of changes in circulation during deliberate apnea. Blood pressure rises significantly often accompanied by bradycardia. Further studies confirmed a massive increase of total vascular resistance as it also happens in shock to maintain perfusion of heart, lung and brain. This study is to determine the exact alterations of the cardiac function during this reaction, show the redistribution of blood volume in apnea and evaluate possible longterm effects on the central nervous system caused by repeated apnea via magnetic resonance imaging. 