The normal value of blood pressure differential is between 30-60 mmHg, and is normal within this range. Some patients are outside the normal range, mainly in the following cases: 1. Aortic valve closure insufficiency. In such patients, a large amount of blood from the aorta flows back into the left ventricle during diastole, which can cause an increase in systolic blood pressure, a decrease in diastolic blood pressure, and an increase in the pressure difference between the blood pressure and the diastolic blood pressure.2. Elderly people with atherosclerosis. These patients are characterized by poor elasticity of large arteries, causing high systolic blood pressure, low diastolic blood pressure, and large pressure difference.3. Increased heart rate. It is mainly seen in young people, manifested by excessive activation of sympathetic nerves, which makes the systolic period of the heart relatively prolonged and the diastolic period relatively shortened, leading to increased diastolic pressure and causing a small pressure difference.4. Increased peripheral vascular resistance. In this kind of patients, the resistance of blood flow from the aorta to the periphery increases, which can also cause the diastolic blood pressure to rise and the differential pressure to become smaller.