Histamine liberation related to cardiopulmonary bypass in children: possible relation to transient postoperative arrhythmias.

Tumor necrosis factor-alpha production and products of mast cell, basophil, and eosinophil degranulation (prostaglandin D2, histamine, and eosinophil cationic protein) were prospectively studied in 26 children undergoing cardiac operations. The relationship between inflammatory response to cardiopulmonary bypass and transient postoperative arrhythmias was analyzed. Cardiopulmonary bypass was conducted with circulatory arrest and deep hypothermia in 10 patients and with continuous low-flow and moderate hypothermia in 16 patients. Transient postoperative arrhythmias diagnosed on standard or atrial electrocardiograms (or both) were seen in eight of the 26 examined children: accelerated junctional rhythm (n = 3), junctional ectopic tachycardia (n = 3), second-degree atrioventricular block (n = 1), and third-degree atrioventricular block (n = 1). Children with transient postoperative arrhythmias were younger than those without (p < 0.05). Compared with baseline values, there was in all patients a significant release of histamine and eosinophil cationic protein (p < 0.05) related to cardiopulmonary bypass, reaching peak values 4 hours after the operation. In contrast, tumor necrosis factor-alpha production and prostaglandin D2 release were not significant. This suggests that activated basophils but not mast cells are the major sources of histamine liberated during and after cardiopulmonary bypass. Histamine release but not eosinophil cationic protein release correlated with circulatory arrest and deep hypothermia (p < 0.05), suggesting the participation of physicochemical alterations of circulating basophils leading to histamine liberation. Four hours after the operation, patients with transient postoperative arrhythmias had significantly higher blood concentrations of histamine (p < 0.02) and eosinophil cationic protein (p < 0.05) than did those without transient postoperative arrhythmias. On the first postoperative day, four of the eight patients with transient postoperative arrhythmias had persisting elevated histamine levels, whereas in patients without transient postoperative arrhythmias histamine reached baseline values. The multivariate analysis retained histamine release and eosinophil cationic protein variations related to cardiopulmonary bypass for the emerging model to predict transient postoperative arrhythmias. The results of this study show significant histamine release related to cardiopulmonary bypass. Furthermore, they document a possible relationship between circulating histamine and transient postoperative arrhythmias. The latter may therefore be suspected among the consequences of the inflammatory response to cardiopulmonary bypass.