Adrenomedullin in patients at high risk for pulmonary hypertension

Background. Adrenomedullin is a newly identified peptide with profound hypotensive effects. We investigated perioperative adrenomedullin levels among patients with congenital heart disease with and without pulmonary hypertension. Methods. Levels of plasma adrenomedullin, endothelin-l, and nitric oxide metabolites were measured in three groups: (1) low pulmonary now (n = 11); (2) high flow/low pulmonary arterial pressure (less than 60% systemic pressure) (n = 9); and (3) high flow/high pressure (n = 10). Samples were obtained preoperatively, on and oft: pump, and 3, 6, and 12 hours after bypass. Results. Adrenomedullin levels were highest in the low pulmonary flow group (189.7 +/- 15 pg/mL low now versus 103.1 +/- 9.5 pg/mL high flow/low pulmonary and 139 +/- 17.5 pg/mL high flow/high pressure at 12 hours; p less than or equal to 0.05). The arterial pressure/systemic pressure remained significantly lower in the high flow/low pulmonary pressure compared with the high flow/high pressure group (0.37 +/- 0.08 versus 0.62 +/- 0.11; p < 0.005). Perioperative endothelin-l and nitric oxide levels remained low in the low pulmonary now group but increased progressively in both high now groups. Conclusions. Circulating plasma adrenomedullin appears to affect baseline vascular tone in patients with intact endothelial function. It may interact with nitric oxide and endothelin-l to help regulate blood pressure perioperatively in patients with congenital heart disease. (C) 1998 by The Society of Thoracic Surgeons.