Angina, also known as angina pectoris, is chest pain, usually due to not enough blood flow to the heart muscle."Angina is usually due to obstruction or spasm of the arteries that supply blood to the heart muscle.Other causes include anemia, abnormal heart rhythms and heart failure. The main mechanism of coronary artery obstruction is atherosclerosis as part of coronary artery disease. The term derives from the Latin angere and pectus, and can therefore be translated as ""a strangling feeling in the chest"".There is a weak relationship between severity of pain and degree of oxygen deprivation in the heart muscle. In some cases, angina can be quite severe, and in the early 20th century this was a known sign of impending death. However, given current medical therapies, the outlook has improved substantially. People with an average age of 62 years, who have moderate to severe degrees of angina have a 5-year survival rate of approximately 92%.