Purpose: Human atrial natriuretic peptide (h-ANP) elicits biological effects such as natriuresis, diuresis, and vasodilation, and plays a role in regulating pulmonary circulation. We conducted this clinical study to define its role and elucidate its mechanisms.
Methods: Twelve consecutive adult patients scheduled to undergo cardiac surgery with cardiopulmonary bypass (CPB) were prospectively selected for this study. After the completion of surgery, h-ANP was infused from the right atrium through a Swan-Ganz (S-G) catheter. Blood samples for measurement of ANP and cyclic guanosine monophosphate (cGMP), the second messenger of ANP, were drawn from the pulmonary artery (PA) through the S-G catheter and from the left atrium (LA) through the left atrial pressure line, before and after the infusion of h-ANP. Hemodynamic values were measured at the same time.
Results: After the h-ANP infusion, the plasma levels of ANP were significantly lower in the LA than in the PA, whereas the plasma levels of cGMP were significantly higher in the LA than in the PA. The infusion of h-ANP decreased the mean PA pressure significantly, and the systolic PA pressure remarkably.
Conclusion: The infusion of h-ANP after cardiac surgery stimulates the secretion of cGMP from the pulmonary vascular bed and dilates the PA, thereby decreasing the PA pressure.