A person with a vascular occlusion has a blocked artery. Arteries carry blood from the heart, to the body. The blockage interrupts the flow of blood to the tissue supplied by the artery. The tissue starts to die when it does not receive oxygen and nutrients from the blood.

In most cases, a vascular occlusion is caused by a blood clot in an artery. Blood clots are more common in those who have atherosclerosis.

Occasionally, an artery may be come blocked with air, which is called an air embolism.