[Pathophysiology of heart failure and the biomarkers; brain natriuretic hormone as the class-1 recommendation by the new Japanese Guideline for Heart Failure].

The failing heart produces a variety of biologically active humoral factors such as catecholamines, vasopressin, angiotensin II, aldosterone, atrial natriuretic polypeptide (ANP), brain natriuretic polypeptide (BNP), cytokines and so on, in order to recover the cardiac function through the mechano- and chemo-receptors in vivo. In particular, it has recently shown that the central nervous system plays a pivotal role in the progression of cardiac remodeling and the heart failure. Thereby, endogenous digitalis-like factor, angiotensisn II, aldostereone, and inflammatory cytokines in the brain are acting as the mediators. In fact, mineralocorticoid receptor blockers, such as spironolactone and eplerenone, are clinically useful to treat cardiac failure. However, these biomarkers are not available as laboratory tests because they are under investigation clinically. On the other hand, failing heart by itself produces natriuretic hormones such as ANP and BNP to rescue it. They dilate resistant vessels to reduce the afterload of the heart with the lowest concentrations. Then, natriuresis is caused with the increased concentrations to reduce the pre-load to the heart. The natriuresis is brought partially by reducing concentrations of plasma aldosterone. Therefore, concentrations of these natriuretic hormones are excellent biomarkers for the cardiac function. They increase in a variety of disease states like hypertension, acute/old myocardial infarction, angina pectoris, arrhythmias, cardiac failure, cardiomyopathy, renal failure and myocarditis. In particular, they are remarkably increased in patients with heart failure. Recently, a new biomarker, N-terminal pro-BNP (NT-proBNP) is registered as a clinically available laboratory test, which may be superior to BNP at the laboratory stand of view. It is because NT proBNP is not degraded in the circulation, stable even in serum and the higher concentration as compared to BNP.