Blood BNP refers to blood B-type brain natriuretic peptide, which is secreted by the ventricular muscle of human heart and is physiologically active, with the effects of sodium, water and vasodilatation. Its clinical significance is mainly the following three points: 1, to make the diagnosis and differential diagnosis of acute or chronic heart failure, and its differential diagnosis is more significant than the diagnosis. 2, to guide the role of treatment, if the heart failure after active treatment If BNP decreases more than 30% of the baseline after active treatment, it indicates that the patient has a good treatment effect, and vice versa. 3, blood BNP also has the function of guiding the patient’s prognosis, but when the baseline blood BNP is very high at the time of admission, exceeding 5000 pg/ml, it indicates that the patient’s long-term prognosis and near-term prognosis are not good.