[Atrial and B-type natriuretic peptides: from the research lab to clinical practice]

The heart produces two related hormones, atrial (ANP) and B-type natriuretic peptides (BNP). Both are synthesized in the atria and ventricles as polypeptides, which upon release are split into ANP and BNP and the N-terminal fragments N-ANP and N-BNP (together named natriuretic peptides, NPs). The most important function of ANP and BNP is protection against volume-overload, by increasing natriuresis and diuresis amongst other things. Both peptides can be considered the natural antagonist of the renin-angiotensin system. Clearance occurs through a specific receptor and through enzymatic break-down by neutral endopeptidase (NEP). All 4 NPs circulate in plasma. Elevated concentrations of NPs are found when the filling pressures of the heart are elevated, as in acute coronary syndromes and congestive heart failure. Measurement of NPs is a useful tool in the differential diagnosis of cardiac versus non-cardiac dyspnoe (high negative predictive value), in the identification of heart failure patients most at risk and in optimising therapy in heart failure. In right ventricular overload caused by (corrected) congenital heart diseases and acute lung embolism, NP concentrations are also elevated, as they are in renal failure and in hypertension associated with left ventricular hypertrophy. Infusions of ANP and BNP lead to increased natriuresis and diuresis. Pharmacologically, increases in ANP and BNP can be accomplished with NEP-inhibitors or beta-blockers. Measurement of NP(s) will become as important for estimation of heart function as creatinine is for estimation of renal function.