What causes angina angina pectoris?

Under the protection of the question that angina angina pectoris causes? The answer is when the blood flow decreases to the heart area, it harms the supply of nutrients and oxygen needed for myocardial cells. When this happens, the heart is forced to use alternative and less efficient stretch to perform the task of pumping blood in and from the body. The side product of the less efficient source of energy. It is a chemical compound called lactic acid (lactic acid), which accumulates in the muscles and causes pain. Some medications to treat angina are done by preventing the use of this energy source.