The pressure of blood flowing in the arteries is called arterial blood pressure (hereinafter referred to as blood pressure), and the relative constancy of blood pressure is an important condition to maintain life. Maintaining the relative stability of blood pressure requires the normal pumping function of the heart and the circulation of the arteriovenous pipeline system. Each person’s heart is no more than the size of his or her fist, do not look at its small size, but its work can be unusual, the average normal heart beats about 100,000 times a day, pumping out more than 7,000 liters of blood, travel nearly 100,000 kilometers. In order to complete the heart’s pumping function, the heart is divided into four chambers, blood containing carbon dioxide from the body’s venous system, first back to the right atrium, through the right ventricle into the lungs. In the lungs, carbon dioxide and oxygen are exchanged in the venous return blood, and fresh blood containing oxygen then flows from the pulmonary veins through the left atrium and into the left ventricle. When the left ventricle contracts, oxygenated arterial blood is ejected into the aorta, where it is transported to tissues throughout the body through branches of arteries at various levels like tree branches to meet the needs of tissue metabolism. The metabolic products produced during tissue metabolism, such as carbon dioxide, are carried back to the right atrium by the venous blood. This circumferential movement of blood is called the circulation. The driving force of blood circulation is blood pressure. Blood pressure is the result of the action of two forces, the contractile force of the left ventricle and the resistance of the arterial system. In addition, blood pressure is susceptible to fluctuations due to a variety of physiological and pathological factors. Physiological factors such as high intensity exercise, mental stress, and sudden excitement can have a momentary rise, and often rise after a full meal, all of which are normal reactions. Hypertension due to pathological factors is one of the most common cardiovascular diseases, especially in the middle-aged and elderly population. The blood pressure during the systolic period of the heart is called the systolic pressure, which is the larger number when the blood pressure is measured and indicates the pressure in the arteries when the heart is discharging blood. After each contraction of the heart, it loosens up and the blood refills the heart chambers, and during this period, the pressure in the arteries is called the diastolic pressure, which is the smaller number. The systolic pressure is usually written in front of the diastolic pressure, e.g., a person’s systolic pressure is 110 millimeters of mercury (mmHg) and diastolic pressure is 70 mmHg, written 110/70 mmHg.