Clinical significance of atrial natriuretic peptide in human blood

In an attempt to clarify the clinical significance of atrial natriuretic peptide (ANP) in man, plasma levels of immunoreactive ANP were studied in patients with heart diseases and in those with chronic renal failure. When ANP concentrations in pulmonary arterial plasma were compared with hemodynamic variables in patients with heart diseases who underwent cardiac catheterization, a significant positive correlation was found between plasma ANP levels and mean pulmonary capillary wedge pressure, while plasma ANP levels were not significantly correlated to mean right atrial pressure (MRAP). After the injection of contrast medium, both MRAP and plasma ANP levels increased and a significant positive correlation was observed between two variables. Plasma levels of ANP were elevated in patients with congestive heart failure according to the severity. In addition, patients associated with atrial fibrillation showed significantly higher plasma ANP levels than those on sinus rhythm. In patients with paroxysmal atrial arrhythmias, plasma ANP levels increased markedly during paroxysms. Patients with chronic renal failure had elevated plasma ANP levels, which fell after hemodialysis. These results suggest that both left and right atrial tissue can secrete ANP as a result of stretching of the cardiocytes in man and that plasma ANP levels are elevated in patients with congestive heart failure and in those with chronic renal failure by increased atrial pressure due to volume expansion. Abnormal atrial contraction per se, in addition, may stimulate ANP secretion.