Correlation of plasma adrenomedullin to myocardial preservation during open-heart surgery

Adrenomedullin (ADM) is a vasoactive peptide with potent dilatory effects. We studied whether perioperative myocardial injury could be altered by the presence of ADM. Blood samples from 19 children with congenital heart disease undergoing surgical repair were collected at six time points: preoperative, on cardiopulmonary bypass (CPB), and 0, 3, 6, and 12 hours after CPB. Blood levels of ADM (pg/ml) and troponin-I (Tn-I; ng/ml), a specific marker of myocardial injury, were measured. Patients were divided into three groups based on their 12-hour Tn-I levels (I, < 10, n = 6; II, 10-25, n = 6; III, >25, n = 7). Preoperative Tn-I levels were within the normal range for all patients. Preoperative ADM levels in group I (with little or no evidence of myocardial injury) were significantly greater than those of either group II or III (242.7 +/- 15.4 vs 83.8 +/- 18 and 85.2 +/- 5.5, respectively; p < or = 0.0001 for each). The 12-hour ADM levels in group I remained significantly lower than preoperative levels (242.7 +/- 15.4 vs 197.4 +/- 11.6, p < or = 0.03) but higher than in the other groups. In group III, ADM increased at the 12-hour time point (159.2 +/- 6.5, p < or = 0.0001 vs baseline). Higher preoperative ADM levels are associated with lower levels of myocardial injury (as assessed by troponin-I release) during congenital heart surgery.