Angina pectoris is the medical term used to denote chest pain due to reduced blood supply to the heart. It can also result due to a mismatch between the supply and demand. Usual cause of angina pectoris is blockage of the blood vessels supplying oxygenated blood to the heart (coronary arteries). But a supply demand mismatch situation can occur if the heart muscles are grossly thickened even if the blood vessels are not narrowed. In this situation the normal blood vessels are not able to meet the increased oxygen requirement of the thickened heart muscles, especially during exercise. Angina pectoris classically occurs on effort and is relieved by rest. But in severe forms the pain can occur at rest as well.
Angina pectoris can also occur due to transient contraction of the muscle surrounding the blood vessels supplying the heart known as coronary vasospasm. This form of angina is called variant angina or Prinzmetal’s angina. ECG changes in Prinzmetal’s angina may mimic that of a heart attack, but the changes are transient and normalize when the chest pain subsides.