Natriuretic peptides are substances made by the heart. Two main types of these substances

are brain natriuretic peptide (BNP) and N-terminal pro b-type natriuretic peptide (NT-

proBNP). Normally, only small levels of BNP and NT-proBNP are found in the bloodstream.

High levels can mean your heart isn't pumping as much blood as your body needs. When this

happens, it's known as heart failure, sometimes called congestive heart failure.