The grading of pulmonary artery pressure is divided into the following three types: the first, according to the severity grading, is divided into mild is 26-35mmHg, moderate 36-45mmHg, severe greater than 45mmHg. the second, according to the pathological grading, stage 1 is the small peripheral arteries have abnormal muscle tissue expansion into the normal muscular blood vessels have a mild thickening of the wall of the blood vessels, the thickening of the wall of the blood vessels is less than 1.5 times of the normal.2 stage is the further growth and hypertrophy of muscle tissue, and the thickness of the middle layer of the wall is 1.5-2 times normal. stage 3 in addition to the above changes, the number of blood vessels decreases, the blood vessels become thinner, and the resistance of the pulmonary circulation increases. The third, functional grading, is divided into Grade I, with no limitation of physical activity. Grade II, mild limitation of physical activity, asymptomatic at rest, daily activities can cause dyspnea, fatigue, chest pain or even syncope. Grade III, asymptomatic at rest, less than daily activities can cause the above symptoms. Grade IV, inability to engage in any physical activity, dyspnea, fatigue and other symptoms at rest, as well as signs of right heart failure, aggravated by any physical activity.