Plasma adrenomedullin level after cardiopulmonary bypass.

Adrenomedullin is an intrinsic vasodilator which is metabolized mainly in the pulmonary circulation. We measured plasma levels of adrenomedullin in children with congenital cyanotic heart disease (CY group, n = 6), children with high pulmonary blood flow due to congenital heart disease (PH group, n = 8), and in adults with mitral valve disease (MV group, n = 7) before and 3 h after cardiopulmonary bypass (CPB). Before CPB, the adrenomedullin level was the highest in the MV group, possibly due to chronic heart failure. Three hours after CPB, the plasma adrenomedullin level (pg/ml) increased to 1712.7 +/- 498.4 in the CY group, 167.6 +/- 26.4 in the PH group, and 1404.3 +/- 313.7 in the MV group, the level in the PH group being significantly lower than the rest. In the PH group, there was statistically significant negative correlation between the mean pulmonary arterial pressure at the preoperative catheter study, and the adrenomedullin level 3 h after CPB. These results illustrate that the adrenomedullin level increased after CPB, but that the increase was less marked in the PH group, implying that where the pulmonary vasculature was damaged most, this results in increased vasoconstriction.