The pain is characterized by paroxysmal anterior chest crushing pain or dullness, mainly in the posterior part of the sternum, but also radiating to the precordial area and the ring finger of the left upper limb, and often occurs under the stimulus of exertion, mood swings, satiety, cold, etc. The duration of angina pectoris varies from 3-5 minutes to no more than 30 minutes, and can be relieved within a few minutes after resting or taking nitroglycerin, but these patients should be especially vigilant and go to the hospital when the symptoms are not relieved.