Brain-type Natriuretic Peptide (BNP) is a nonglycosylated peptide that is produced predominantly byventricular myocytes and belongs to the natriuretic peptide family. Proteolytic cleavage of the 12 kDa BNPprecursor gives rise to N-terminal Pro BNP (NT-proBNP) and mature BNP. N-terminal proB-type natriureticpeptide (NT-proBNP), a useful marker of heart failure (HF), is considered to be secreted mainly from theventricle, increased serum NT-proBNP levels are also encountered in conditions such as atrial fibrillation (AF)and atrial septal defect in patients without HF.