Low energy biphasic waveform cardioversion of atrial arrhythmias in pediatric patients and young adults.

BACKGROUND

Low-dose biphasic waveform cardioversion has been used for the termination of atrial arrhythmias in adult patients. The energy required for termination of atrial arrhythmias in pediatric patients is not known. The objective of this study is to determine the minimum energy required for successful external cardioversion of atrial arrhythmias in pediatric patients using biphasic waveform current.

METHODS

Prospective study of all patients less than 24 years of age with and without congenital heart disease undergoing synchronized cardioversion for atrial arrhythmias. Patients were assigned to receive an initial biphasic energy shock of 0.2-0.5 J/kg and if unsuccessful in terminating the arrhythmia, subsequent sequential shocks of 1 and 2 J/kg would be administered until cardioversion was achieved. The end point of the cardioversion protocol was successful cardioversion or delivery of three shocks.

RESULTS

Between June 2005 and June 2006, 16 patients underwent biphasic cardioversion for atrial flutter or fibrillation. The mean age was 14.7 +/- 6.4 years (range: 2 weeks to 24 years). The mean weight was 51 +/- 21 kg (range: 3.8-82 kg). Seven patients had normal cardiac anatomy, three had a single ventricle (Fontan), two had a Senning operation; the remaining four patients had varied forms of congenital heart disease. The median length of time that the patients were in tachycardia was 12 hours (range: 5 minutes to 2 months). Using either transthoracic echocardiography (TTE) or transesophageal echocardiography (TEE), no thrombi were identified in any patient. All patients were successfully cardioverted with biphasic waveform energy. The successful energy shock was 0.35 +/- 0.19 J/kg (range: 0.2-0.9 J/kg). All but one patient were successfully cardioverted with less than 0.5 J/kg. The transthoracic impedance range was between 41 and 144 Omega; one patient had an impedance of 506 Omega (2-week-old infant with a weight of 3.8 kg). The mean current delivered was 5.4 +/- 2.2 A (range: 1-11 A).

CONCLUSION

Low-dose energy using biphasic waveform shocks can be used for successful termination of atrial arrhythmias in pediatric patients with and without congenital heart disease.