Histamine release during paediatric cardiopulmonary bypass

Mast cell activation and arterial hypotension during proximal aortic repair requiring hypothermic circulatory arrest

OBJECTIVE

Aortic surgeries requiring hypothermic circulatory arrest evoke systemic inflammatory responses that often manifest as vasoplegia and hypotension. Because mast cells can rapidly release vasoactive and proinflammatory effectors, we investigated their role in intraoperative hypotension.

METHODS

We studied 31 patients undergoing proximal aortic repair with hypothermic circulatory arrest between June 2013 and April 2015 at Duke University Medical Center. Plasma samples were obtained at different intraoperative time points to quantify chymase, interleukin-6, interleukin-8, tumor necrosis factor alpha, and white blood cell CD11b expression. Hypotension was defined as the area (minutes × millimeters mercury) below a mean arterial pressure of 55 mm Hg. Biomarker responses and their association with intraoperative hypotension were analyzed by 2-sample t test and Wilcoxon rank sum test. Multivariable logistic regression analysis was used to examine the association between clinical variables and elevated chymase levels.

RESULTS

Mast cell-specific chymase increased from a median 0.97 pg/mg (interquartile range [IQR], 0.01-1.84 pg/mg) plasma protein at baseline to 5.74 pg/mg (IQR, 2.91-9.48 pg/mg) plasma protein after instituting cardiopulmonary bypass, 6.16 pg/mg (IQR, 3.60-9.41 pg/mg) plasma protein after completing circulatory arrest, and 7.64 pg/mg (IQR, 4.63-12.71 pg/mg) plasma protein after weaning from cardiopulmonary bypass (each P value < .0001 vs baseline). Chymase was the only biomarker associated with hypotension during (P = .0255) and after (P = .0221) cardiopulmonary bypass. Increased temperatures at circulatory arrest and low presurgical hemoglobin levels were independent predictors of increased chymase responses.

CONCLUSIONS

Mast cell activation occurs in cardiac surgery requiring cardiopulmonary bypass and hypothermic circulatory arrest and is associated with intraoperative hypotension.

Histamine release during adult cardiopulmonary bypass

Histamine, an inflammatory mediator in its own right, may also be a marker for a more widespread systemic inflammatory process. In this study we have examined variations in plasma histamine concentrations produced during the course of cardiac surgery involving cardiopulmonary bypass, the relationship between these variations and intra-operative events. By assays of serum tryptase and CD-63 expression we have also attempted to identify the source of histamine. Histamine concentrations that were significantly raised from baseline level were demonstrated. These were elevated from the time of aortic cross-clamping and continued to be raised for 24 h postoperatively (p < 0.00625). This was associated with an increase in CD-63 expression (p < 0.025) (but not an increase in tryptase concentration) following aortic cross-clamping and protamine administration, suggesting that basophils are the source of histamine. 41% of patients had arrhythmias in the post bypass period. The rise in histamine levels was not related to the incidence of cardiac arrhythmias.

Release of markers of myocardial and endothelial injury following cold cardioplegic arrest in pigs

Cold cardioplegic arrest causes reperfusion injury to both endothelium and myocardium. We investigated release of troponin-T (TnT), tissue plasminogen activator activity (t-PA) and histamine (HA) from the heart before and after 2h of cold crystalloid cardioplegia in eight Swedish landrace pigs. Coronary sinus blood flow was measured in an external shunt between the coronary sinus and the right atrium. TnT, t-PA and HA were measured concomitantly in arterial and coronary sinus plasma, and the cardiac release was calculated. Cardiac release of TnT increased from 18 (15-25) micrograms/min (median (central 90% percentile)) before cold cardioplegia to maximum 281 (132-510) micrograms/min 30 min after aortic declamping (p < 0.02 vs initial value). t-PA rose from -4 (-52-34) to maximum 249 (75-691) IU/min 2 min after declamping (p < 0.01) and thereafter returned to baseline levels. The net cardiac release of HA was 72 (-80-1321) nmol/min before cardioplegia, rising to 234 (-188-524) after 2 min of reperfusion (p < 0.02) and returning to baseline after 30 minutes. We conclude that the porcine heart releases t-PA, Tn-T and HA during postcardioplegic reperfusion. The differing kinetics of their release may indicate different affection of the myocardium and the endothelium. Tn-T, t-PA and HA are potential markers of myocardial and endothelial injury in the porcine heart.

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.

Open heart surgery increases the levels of histamine in arterial and coronary sinus blood

The possible release of histamine into the coronary circulation during reperfusion of the cold, cardioplegic heart was investigated during open heart surgery in 13 patients (cardioplegic arrest 54 (35-120 min) (median (range)), cardiopulmonary bypass (CPB) 96 (65-360) min. Samples were drawn concomitantly from coronary sinus and arterial blood before cardioplegia and during myocardial reperfusion for measurement of histamine (radioenzymatic method). Additional arterial samples were drawn pre-, per- and postoperatively. CPB induced a sustained increase in arterial histamine (from 4.02 +/- 2.71 nmol/l preoperatively (mean +/- SD) to maximum 16.31 +/- 7.12 nmol/l, p < 0.009). Immediately before cardioplegia histamine levels were higher in arterial than coronary sinus blood (9.24 +/- 4.85 versus 4.04 +/- 2.07 nmol/l, p < 0.002). During myocardial reperfusion coronary sinus histamine increased to levels similar to that of arterial blood. In conclusion, histamine is released during CPB. Before cardioplegic arrest, there is a net uptake of histamine by the heart, which is abolished during reperfusion, possibly due to increased cardiac release of histamine.

Histamine release during paediatric cardiopulmonary bypass

Histamine release is part of the general inflammatory response and occurs during surgery and cardiopulmonary bypass (CPB) in adults. Few data are available for children. Histamine release was studied in 23 children undergoing CPB with standard anaesthetic and CPB techniques. Blood sampling was performed in relation to specific anaesthetic and surgical events, e.g., start of CPB, removal of aortic clamps, reventilation of the lungs. Plasma histamine was determined by a single isotope radioenzymatic technique. There was no consistent histamine release in the study population although there was an increase in plasma histamine concentration in some subjects after initiation of CPB (P < 0.05) and on removal of the aortic cross-clamp (P < 0.05). No correlation was demonstrated between histamine concentration and systolic arterial pressure, temperature, duration of CPB or cross-clamp time. Histamine concentration was positively correlated with heart rate.