Angina is often caused by myocardial ischemia and hypoxia, with paroxysmal chest pain as the main clinical manifestation, commonly seen in stable angina. Angina pain site, pain nature, duration, triggering factors and relief mode have more obvious characteristics: 1, pain site: angina is often located in the posterior sternum or left anterior chest, the scope is not limited, can radiate to the neck, throat, jaw, upper abdomen, back of the shoulder, left arm, left finger side, etc.; 2, pain nature: each patient pain sensation is not exactly the same, part of the patients will feel the chest is tight feeling Some patients will feel a sense of tightness, cramping, pressure, burning, chest suffocation, chest tightness or even suffocation, while some patients may only feel chest discomfort, without much pain, there are certain individual differences; 3, duration: angina is usually paroxysmal attacks, the duration is generally short, 3-5 minutes will gradually disappear; 4, triggering factors: the onset of angina is usually related to physical activity or emotional excitement and other factors, some patients Because of cold, too full, hypertension attacks and other reasons, may also cause angina; 5, relief mode: angina patients can often be relieved after lifting the triggering factors, rest for a period of time, but also sublingual nitroglycerin, angina symptoms can be quickly relieved within a few minutes.