Angina is defined as a clinical syndrome caused by ischemia and hypoxia of the myocardium due to insufficient blood supply to the coronary arteries. Angina can be divided into stable angina and unstable angina. The main clinical manifestation of the symptoms is episodic chest pain, located in the retrosternal or precordial region, often radiating to the left shoulder or left medial arm, pharynx, neck and jaw area. The typical chest pain is compressive or constricting, dull, and also burning, but not sharp. The attack often stops the original activity unconsciously until the symptoms are relieved. It is often triggered by physical work or emotional excitement, and can also occur after a full meal, cold, rainy weather, smoking, or defecation, with paroxysmal onset, ranging from 3-5 minutes in mild cases to 10-15 minutes in severe cases, rarely exceeding 30 minutes.