Pathogenesis of angina pectoris: Angina pectoris occurs when there is a contradiction between the blood supply and demand of the coronary arteries, and the coronary blood flow fails to meet the needs of the myocardial metabolism, causing acute and temporary ischemia and hypoxia of the myocardium. Coronary blood supply and demand imbalance, there are several situations: First, in the coronary artery lesions lead to narrowing of the lumen and dilatation on the basis of the weakening, due to physical labor or emotional excitement, so that the heart load suddenly increased, the myocardial oxygen consumption increased. Coronary artery spasm occurs, resulting in a decrease in coronary blood flow. Third, a sudden decrease in circulating blood flow occurs, resulting in a sudden decrease in coronary blood flow perfusion, causing an imbalance between blood supply and demand.