Ischemia

Ischemia [ ɪsçɛmi ː ] ( from Ancient Greek ἴσχειν / ἔχειν is-chein/echein " hold back " and αἷμα haima " blood ") is a reduced blood flow or a full blood circulation failure of a tissue or organ.

Causes

The cause of ischaemia is usually a change in blood vessels in the form of a constriction or a closure. This can occur, for example in thrombosis or embolism.

The narrowing is called stenosis, such as atherosclerosis and arterial occlusive disease ( AOD). There may also be functionally related restrictions, so the Raynaud's disease, or as a physiological response in the circulation shock.

Occurrence and consequences

Ischemia can temporarily ( " passager " ) occur and remain without consequences for the less supplied tissue. Lasts longer than the tissue ischemia tolerated, or is the insufficient supply so strong that a permanent tissue damage threatens called the state of critical ischemia.

By ischemia, the cellular metabolism is impaired or not. Ischemia is often accompanied by a lack of oxygen in the affected area. Prolonged deficiency it can lead to death (necrosis ) of cells come ( " infarct ", eg, heart attack). A pressure-induced ischemia with tissue damage leads to pressure ulcers ( pressure sores ).

The tolerated without permanent tissue damage period ( ischemia ) is different from organ to organ. It is for the brain of a few minutes to many transplantable organs such as heart or kidney, depending on the cooling system and nutrient solution, and a few hours for more than 12 hours some of the extremities.