To establish the range of BS and ES (m/s) of normal carotid artery by using ultrafast pulse wave velocity (UFPWV), and to explore the influencing factors.

With the gradual aging of Chinese population and continuous development of economy and society, the incidence of cardiovascular disease and the number of patients have increased rapidly. The National Heart Center has reported that the number of patients with clinically diagnosed cardiovascular disease in China has reached 290 million in 2016 (240 million in 2014). Cardiovascular disease is the most common cause of death in humans, accounting for nearly 60% of all deaths worldwide. The updated data from World Health Organization (WHO) in 2008 have shown that atherosclerosis and hypertension are the major diseases of the cardiovascular system. Therefore, early detection of arteriosclerosis, timely treatment and early evaluation of therapeutic efficacy are of great significance for the overall control and reduction of the incidence and mortality of cardiovascular disease.

Carotid artery intima-media thickness (IMT) is often used to evaluate early atherosclerosis, but IMT reflects the change of vascular wall structure. In the early stage of atherosclerosis, the changes of vascular elasticity and resistance occur earlier than those of arterial wall thickening. Therefore, accurate evaluation of vascular function plays an important role in the early diagnosis of atherosclerosis.

Basic and clinical studies and clinical data have shown that pulse wave velocity (PWV) is a reliable index for early evaluation of atherosclerosis. The blood is pumped from the left ventricle during systole, and travels along the arterial system to form pulse wave. Its propagation velocity between two fixed points is the PWV. Atherosclerosis leads to the increased PWV. The detection of PWV can accurately reflect the distensibility and stiffness of arterial wall, thereby early detecting atherosclerosis.

There are three main methods for non-invasive pulse wave measurement: Photoelectric sensor is used to measure and record photoplethysmography signal. Pressure sensor is utilized to record pressure wave signals produced by arterial pulsation on the body surface. Ultrasonic Doppler sensor is applied to collect photoplethysmography signal. Photoelectric sensor acquisition system is difficult to distinguish the pulse waves between the large artery and the capillary arteriole, cannot detect the signal of the deep aorta, is easily affected by the electrical signals of perivascular tissue, and has not been widely used in the clinic. Pressure sensor can be used to collect pressure wave signals, such as brachial-ankle pulse wave. This method has relatively low cost, is often used in clinic, but cannot directly get the pulse wave form and the distance of blood vessel, has many influencing factors and low accuracy. Ultrasonic Doppler technique, such as Echo Tracking and QSA, can reveal deep vein pulse waveforms. However, limited by the traditional ultrasonic processing platform, signal acquisition and formula calculation are complex, and the repeatability is poor. Therefore, the clinical application value is limited. It is urgent to establish a new, simple and precise method for the detection of PWV.

Inclusion Criteria:

• Han nationality
• Age between 18 and 79 years old
• Normal body mass index (18-25 kg/m2)
• Normal blood pressure (139-90/89-60 mmHg)
• No history of cardiovascular disease or respiratory diseases
• Physical examination reveals no abnormalities in cardiovascular and respiratory systems
• Normal blood glucose, blood lipid and electrocardiogram (ECG)
• Echocardiography shows no structural heart disease and normal cardiac function
• Normal carotid ultrasound
• No history of cardiovascular drug use

Exclusion Criteria:

• Heart valve regurgitation with clinical significance or moderate symptom and above
• Respiratory system disease: acute or chronic respiratory disease
• Endocrine diseases: thyroid disease, diabetes mellitus, aldosteronism, pheochromocytoma, and adrenal cortex dysfunction.
• Metabolic syndrome
• Anemia
• Pregnant or lactating women
• Abnormal liver function (more than twice the normal upper limit), abnormal renal function (creatinine > 2 mg/dl), total cholesterol > 190 mg/dl. If Pro-BNP is detected, Pro-BNP is abnormal or in high limit of normal value.
• Connective tissue disease
• Tumor
• Aortic and peripheral vascular diseases: aortic dilatation, aortic dissection, coarctation of the aorta, polyarteritis, atherosclerosis
• Daily drinking: liquor greater than 50 ml; red wine more than 100 ml; beer more than 300 ml
• Professional sportsman
• The poor quality of ultrasonic images cannot meet parameter measurement and analysis

1200 healthy adults with normal physical examination items will be selected from the physical examination center.

According to sex and age stratification, totally 1200 cases will contain 600 males and 600 females.

From 18 to 79 years old, they will be divided into 6 groups: 18-29 years, 30-39 years, 40-49 years, 50-59 years, 60-69 years and 70-79 years (n=200 per group).