What causes angina?

Angina is caused by a temporary lack of oxygen-rich blood to the heart muscle due to a narrowing of the arteries that carry blood to the heart. When the blood flow to an area of the heart is decreased, the supply of oxygen and nutrients to the muscle cells and the heart is reduced.

To maintain its function, the heart muscle will use alternative, less efficient forms of fuel. This causes the muscles to produce lactic acid which causes pain and discomfort around the heart.