A prospective analysis of the incidence and risk factors associated with junctional ectopic tachycardia following surgery for congenital heart disease.

This study was designed to evaluate the incidence and risk factors associated with the occurrence of junctional ectopic tachycardia (JET) in patients after congenital heart surgery. We prospectively analyzed cardiac rhythm status in 336 consecutive patients undergoing surgery for congenital heart disease at our institution during a 1-year period. The incidence of JET was 8% (27/336). Repairs with the highest incidence of JET were arterial switch operation (3/13, 23%), atrioventricular (AV) canal repair (4/19, 21%), and Norwood repair (2/10, 20%). Compared to patients with no arrhythmias, patients with JET were more likely to be younger (2.75 +/- 2.44 vs 5.38 +/- 7.25 years, p < 0.01), have had longer cardiopulmonary bypass times (126 +/- 50 vs 85 +/- 73, p < 0.01), and have a higher inotrope score (6.26 +/- 7.55 vs 2.41 +/- 8.11, p < 0.01). By multivariate analysis, ischemic time was the only factor associated with JET [odds ratio, 1.01 (confidence interval, 1.005-1.02); p = 0.0014). The presence of JET did not correlate with electrolyte abnormalities. JET is not necessarily related to surgery near the His bundle or hypomagnesemia. Longer ischemic time is the best predictor of JET. Patients undergoing arterial switch operation, AV canal repair, and Norwood repair are at highest risk of postoperative JET and should be considered for prophylactic therapy.

Efficacy of biphasic waveform compared to monophasic waveform for cardioversion of atrial flutter in pediatric patients.

The efficacy of biphasic waveform cardioversion of atrial flutter in pediatric patients has not previously been demonstrated. Cardioversion outcomes were compared in two sequential groups of patients with atrial flutter undergoing transthoracic cardioversion using monophasic and biphasic waveforms at a single pediatric institution. The mean energy required for procedural success was 1.7 +/- 1.2 J/kg in the monophasic group compared to 0.9 +/- 0.6 J/kg in the biphasic group (p = 0.002). The mean number of attempts before achieving procedural success was 1.9 +/- 1.2 for the monophasic group and 1.3 +/- 1.0 for the biphasic group (p = 0.019). Procedure success rate was 89.5% (33/38) in the monophasic group compared to 100% (27/27) in the biphasic group (p = 0.13). Success rate for biphasic waveform cardioversion was 83% (5/6) when using energy less than 0.5 J/kg. These findings provide the impetus for lower starting energies and more widespread use of devices utilizing biphasic waveforms in pediatric patients.

The clinical course of acquired complete heart block in children with acute myocarditis.

A case of biopsy-proven myocarditis in a 7-year-old complicated by advanced atrioventricular (AV) block prompted a review of the medical literature to determine the prognosis for recovery of AV conduction or need for pacemaker implantation. A total of 40 patients younger than 20 years of age were identified, with return of AV conduction within 7 days in 27 patients (67%), permanent pacing in 11 patients (28%) with persistent AV block, and death in 2 patients (5%).

Acute myocarditis.

Myocarditis is defined as inflammation of the myocardium accompanied by myocellular necrosis. Acute myocarditis must be considered in patients who present with recent onset of cardiac failure or arrhythmia. Often there is a history of an antecedent flu-like illness. Fulminant myocarditis is a distinct entity characterized by sudden onset of severe congestive heart failure or cardiogenic shock, usually following a flu-like illness. Giant cell myocarditis is a rare, frequently fatal disorder of unknown origin characterized by presence of giant cell inflammatory infiltrate in the myocardium. In recent years we have made good progress in understanding the causes, pathogenesis, natural history, diagnosis, and treatment of myocarditis. However, our knowledge is still far from complete. New information that extends our understanding of myocarditis is being reported constantly. This review summarizes recent advances in myocarditis, with an emphasis on the literature during the last year.

Pharmacologic management of arrhythmias in patients with congenital heart disease.

The management of cardiac arrhythmias has evolved rapidly over the past decade. This includes the development of more effective antiarrhythmic medications as well as catheter- and device-based therapies. Antiarrhythmic medications remain the primary treatment modality for most acute arrhythmias; however, the long term use of these medications may be accompanied by severe adverse effects. For this reason, antiarrhythmic medications are increasingly used in conjunction with other forms of therapy, such as catheter ablation or pacemaker implantation. Patients with congenital heart disease often have an increased propensity for cardiac arrhythmias due to both inherent conduction system abnormalities and impaired ventricular function. The purpose of this review is to examine the currently available antiarrhythmic drugs and assess their role in the treatment of arrhythmias in patients with congenital heart disease. It is important to emphasize that patients with congenital heart disease often have hemodynamic limitations and may be at an increased risk for developing adverse effects with antiarrhythmic agents. An awareness of the arrhythmias associated with congenital heart disease, the natural history of these arrhythmias, and the potential benefit of treatment with antiarrhythmic medications versus other forms of therapy provides a rational basis for therapy in this challenging population of patients.