BNP is the abbreviation of brain natriuretic peptide, which is a normal hormone from the body and is secreted by the ventricular and cardiac muscle cells. In normal human body, there is only a small amount of BNP, but in heart failure, the ventricular muscle cells will secrete a larger amount of BNP, so that BNP is helpful to improve the heart function to a certain extent, because it has the effect of vasodilatation and diuretic. In clinical practice, BNP is used to identify whether the dyspnea is due to cardiac or pulmonary causes, but BNP can be measured by blood sampling to rule out cardiac causes of heart failure if BNP is normal or elevated if it is due to heart disease.