The clinical cause of low brain natriuretic peptide is not clear, but it can be used to rule out heart failure, and brain natriuretic peptide can also be used in the prognostic evaluation of patients with heart failure. Brain natriuretic peptide (BNP) is a marker secreted by cardiac cells to indicate the function of the heart, with the effect of vasodilatation and diuresis, mainly with the change of the tension of the ventricular wall, when the ventricular systolic and diastolic function is limited BNP secretion will be increased, when the patient develops heart failure, BNP will increase, and when the BNP is low, it can be used for the exclusion of heart failure. In addition, brain natriuretic peptide can be used in the prognostic evaluation of patients with heart failure. For every 100/mL increase in brain natriuretic peptide concentration in a patient with heart failure, there is an approximate 35% increase in the risk of death in that patient.