The onset of angina is, more often than not, discontinuous. The typical onset of angina is paroxysmal, and the episodes are mainly located in the retrosternal or precordial region, with a range of about palm size and not very clear boundaries, often radiating to the left shoulder, left arm, back, jaw, neck, teeth and other parts of the body. The nature of the pain is mostly dull, and may be accompanied by burning sensation, needle-like pain, and may be accompanied by weakness, fainting, sweating, with a sense of near death, and the symptoms last about 3-5 minutes, or even more than 10 minutes, and gradually relieved by rest, containing drugs such as quick-acting heart pills. The onset of angina can occur once a day or several times a day, or once in several days, and each attack is not continuous.