The causes of low blood pressure are mainly reduced elasticity of large blood vessels, aortic valve closure insufficiency, etc. The harm is mainly the reduction of effective circulating blood volume, and the symptoms of insufficient blood supply. Low pressure is diastolic pressure, which is the pressure generated by the elastic retraction of the arterial vessels when the heart is in diastole. If the diastolic pressure is lowered, it means that the elasticity of the large blood vessels is lowered, which may be due to atherosclerosis; when the aortic valve is closed insufficiently and the heart is diastolic, the blood in the aorta will flow back into the left ventricle, which will result in a lowered diastolic pressure. Reduced elasticity of blood vessels, or incomplete closure of the aortic valve will affect the amount of blood supplied to the heart muscle, and symptoms such as fatigue, shortness of breath, dizziness, and even thrombosis may occur. When low diastolic blood pressure occurs, it is recommended to consult a hospital to find out the cause and then treat it, so as not to cause irreversible damage to the myocardium.