Going into detail on what this term means and how it relates to health guidelines. This article may be incomplete.
Biomarker (blood test) which is produced by the heart (predominantly the left ventricle due to it's larger mass) in response to elevated filling pressures, which is consistent with "Heart Failure." It prompts the kidneys to dump fluid (urinate). The higher the levels in the blood, the more likely someone has "heart failure." It is very specific to the heart and very sensitive.