[Oxygen free radicals in cardiology]

Oxygen free radicals are extremely toxic chemical entities derived from oxygen metabolism. This is a physiological process which explains a great deal of the phenomenon of phagocytosis. Under normal conditions, the body's natural defense mechanism neutralise the oxygen-free radicals as they are produced. In certain pathological situations, a disequilibrium is observed between the free radical aggression and the defense systems which creates an oxidative stress and organ damage. In cardiology, the oxidative stress occurs essentially in the phenomenon of reperfusion ischaemia. It is partially responsible for the reperfusion arrhythmias and myocardial stunning. An irreversible myocardial disease such as myocardial infarction, the responsibility of the oxidative stress is more uncertain. In myocardial protection during cardiac surgery the radical-induced damage occurs without it being possible to demonstrate the phenomenon in irreversible myocardial disease. The role of oxidative stress is unquestionable in myocardial reperfusion ischaemia. The detection of sensitive biological markers and a better understanding of the physiopathology should increase our knowledge of oxygen free radicals and enable effective treatment of their complications.