Value of Regular Defibrillation Threshold Testing After Extracardiac Implantable Cardioverter Defibrillator Placement inSmall Children During Mid-Term Follow-Up.

Abstract

The purpose of this study was to analyze course of defibrillation threshold (DFT) with growth. Data on regular DFT testing after extracardiac implantable cardioverter-defibrillator (ICD) placement in infants and small children is still limited. An extracardiac ICD was placed in 23 pediatric patients (median age 6.1 years; median body weight 21 kg, median length 120 cm). The defibrillator lead was tunneled pleurally, and the device was placed as "active can" in the right upper abdomen or in a horizontal position between the diaphragm and the pericardium, respectively. DFT was verified intraoperatively, 3 months later, and every 12 months thereafter. The aim was to achieve DFT<15 J allowing ICD programming with a double safety margin above DFT. In all 23 patients, an intraoperative DFT<15 J could be accomplished. Serial DFT testing showed an increase from a median DFT of 10 J intraoperatively to 15 J after 1 year. During mean follow-up of 2.0 years, a significant correlation between DFT and body length, but not body weight, was observed. In 4 of 23 (17%) patients, surgical revision was required because of a DFT increase >20 J during regular DFT testing. No complications regarding DFT testing were noted. After extracardiac ICD placement in infants and small children, DFT increase related to body length was evident during mid-term follow-up. Routine serial DFT testing was a safe procedure and identified a significant DFT increase in 4 of 23 patients. Serial DFT testing during follow-up in these patients is recommended.