Perioperative changes in plasma brain natriuretic peptide concentrations in patients undergoing cardiac surgery

The plasma concentrations of brain natriuretic peptide (BNP), a cardiac hormone, were measured in 30 consecutive adult patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) during the perioperative period. BNP concentrations remained unchanged until 6 h after the cessation of bypass, and were elevated 12, 24, and 48 h post-bypass (P<0.0001 versus baseline). They had returned to the baseline values when measured 3 weeks postoperatively. The preoperative plasma BNP concentration correlated significantly with the left ventricular ejection fraction (r=-0.895). The peak plasma BNP concentration 24 h after bypass correlated with the cardiac index (r=-0.64), stroke volume index (r=-0.62), injection rate of dopamine hydrochloride (r=0.65), and aortic crossclamp time (r=0.57). There was also a significant correlation between the preoperative BNP concentration and the plasma BNP concentration 24 h post-CPB. These findings led us to conclude that the plasma concentrations of BNP become markedly and acutely elevated after cardiac surgery with CPB, and reflect the state of left ventricular function. Moreover, the severity of acute heart failure after cardiac surgery can be predicted by the preoperative plasma BNP concentration.