Heart disease. Artwork showing a heart with ischaemia (oxygen shortage) due to a blocked artery. The cardiac tissue beneath the blockage (grey) is being starved of oxygen due to a lack of blood reaching the region. The narrowing and blocking of arteries, known as stenosis, is caused by atherosclerosis. This is when fatty deposits (atheroma) build up inside the artery inner wall, restricting the diameter of the vessel for blood to flow through. When the blood supply to the heart is interrupted, it often leads to a myocardial infarction (heart attack). Treatments for this usually include thrombolytic medicine (dissolves blood clots) and heart bypass surgery.