Pretreatment by hyperoxia--a tool to reduce ischaemia-reperfusion injury in the myocardium.

Atherosclerosis leads to narrowing and occlusion of coronary arteries, resulting in inadequate oxygen supply for maintenance of normal oxidative metabolism. To avoid profound ischaemia and subsequent necrosis of cardiomyocytes, blood flow has to be restored by means of thrombolysis, percutaneous coronary intervention, or surgical revascularisation. Besides restoring oxygen supply to the cells, introduction of molecular oxygen to the ischaemic tissue results in a spectrum of unfavourable events, termed altogether as reperfusion injury. Exposure to hyperoxia for a limited time before ischaemia induces a low-grade oxidative stress and evokes an (ischaemic) preconditioning-like effect in the myocardium, which protects the heart from subsequent injury. This review addresses the effects of pretreatment by hyperoxia both in experimental and clinical setting.