Safety and Efficacy of Prophylactic Amiodarone in Preventing Early Junctional Ectopic Tachycardia (JET) in Children After Cardiac Surgery and Determination of Its Risk Factor

Junctional ectopic tachycardia (JET) occurs commonly after pediatric cardiac operation. The cause of JET is thought to be the result of an injury to the conduction system during the procedure and may be perpetuated by hemodynamic disturbances or postoperative electrolyte disturbances, namely hypomagnesemia. The purpose of this study was to determine perioperative risk factors for the development of JET. Telemetry for each patient admitted to the cardiac intensive care unit from December 1997 through November 1998 for postoperative cardiac surgical care was examined daily for postoperative JET. A nested case-cohort analysis of 33 patients who experienced JET from 594 consecutively monitored patients who underwent cardiac operation was performed. Univariate and multivariate analyses were conducted to determine factors associated with the occurrence of JET. The age range of patients with JET was 1 day to 10.5 years (median, 1.8 months). Univariate analysis revealed that dopamine or milrinone use postoperatively, longer cardiopulmonary bypass times, and younger age were associated with JET. Multivariate modeling elicited that dopamine use postoperatively (odds ratio, 6.2; p = 0.01) and age less than 6 months (odds ratio, 4.0; p = 0.02) were associated with JET. Only 13 (39%) of the patients with JET received therapeutic interventions. Junctional ectopic tachycardia occurred in 33 (5.6%) of 594 patients who underwent cardiac operation during the study period. Postoperative dopamine use and younger age were associated with JET. It may be speculated that dopamine should be discontinued in the presence of postoperative JET.

Early postoperative arrhythmias are a known complication of cardiac surgery; however, little data exists specific to pediatrics. The purpose of this study was to determine the incidence and risk factors associated with the development of arrhythmias immediately after surgery in a pediatric population. Data were collected in a prospective observational format from pediatric patients undergoing cardiac surgery between September 2000 and May 2003. This format included age, anatomy, surgical repair, and serum magnesium and calcium levels, as well as cardiopulmonary bypass and aortic crossclamp times. Patients were continuously monitored, and hemodynamically significant arrhythmias were recorded. Arrhythmias occurred in 28 of the 189 patients enrolled (15%) including 16 with junctional ectopic tachycardia, 7 with complete atrioventricular block, 4 with ventricular tachycardia, and 1 with re-entrant supraventricular tachycardia. Significant differences were found between the arrhythmia and nonarrhythmia groups with regard to age (22 vs 45 months), cardiopulmonary bypass time (189 vs 109 minutes), and aortic crossclamp time (105 vs 44 minutes); P < .05. Magnesium and calcium levels were not significantly different between the groups. Two repairs carried an increased risk: complete atrioventricular septal defect repair, 8 of 11 patients (72%), and the arterial switch 5 of 8 patients (62.5%); P < .05. Atrioventricular septal defects had an even higher incidence when controlled for age, bypass time, and crossclamp time (odds ratio = 7.65). Hemodynamically significant postoperative arrhythmias are a frequent complication of pediatric cardiac surgery. Younger age and longer bypass and crossclamp times are risk factors for arrhythmia. In addition, the repair of atrioventricular septal defects carries an independent risk of arrhythmias.

Junctional ectopic tachycardia is a major cause of postoperative morbidity after surgery for congenital cardiac disease. To elucidate the mechanism of junctional ectopic tachycardia, surgical correlations were studied in four types of congenital heart defects involving closure of a ventricular septal defect, relief of right ventricular outflow tract obstruction, or both. Between 1997 and 1999, a total of 343 consecutive patients underwent repair of tetralogy of Fallot (n = 114), common truncus arteriosus (n = 10), ventricular septal defect (n = 161), and atrioventricular septal defect (n = 58). Variables studied included demographic and bypass data, surgical approaches toward ventricular septal defect closure and relief of right ventricular outflow tract obstruction, and resection as opposed to division of muscle bundles. Junctional ectopic tachycardia occurred most frequently after repair of tetralogy of Fallot (n = 25; 21.9%), with no cases occurring after repair of common trunk, 6 occurring after repair of ventricular septal defect (3.7%), and 6 occurring after repair of atrioventricular septal defect (10.3%). Stepwise logistic regression revealed that resection of muscle bundles (P <.0001), higher bypass temperatures (P <.03), and relief of right ventricular outflow tract obstruction through the right atrium (P <.05) significantly and independently predicted postoperative junctional ectopic tachycardia. Relief of right ventricular outflow tract obstruction appears to be more important in the causation of junctional ectopic tachycardia than does ventricular septal defect closure, which may explain the higher incidence of this complication after tetralogy of Fallot repair. Muscular resection seems to be more arrhythmogenic than is simple division. Increased traction through the right atrium for relief of right ventricular outflow tract obstruction would fit the hypothesis that enhanced automaticity of the His bundle, the morphologic substrate for junctional ectopic tachycardia, may result from direct trauma or infiltrative hemorrhage of the conduction system. When feasible, techniques avoiding both extensive muscle resection and excessive traction should be applied during resection of right ventricular outflow tract obstruction.