Use of a Transvenous Endocardial Lead as a Shock Cord Placed Subcutaneously in an Infant with Congenital Long QT Syndrome

Abstract

Congenital long QT syndrome (LQTS) after birth was diagnosed in a boy noted to have a 2:1 atrioventricular block during the fetal period. Medication with mexiletine hydrochloride was started, but loss of consciousness and rigidity of limbs occurred during napping. At the first clinical ventricular fibrillation (VF), cardiopulmonary resuscitation (CPR) was immediately initiated, and his heart rhythm was restored by electrical defibrillation by emergency services. Although he recovered without severe neurological sequelae, Torsade de pointes subsequently occurred and an implantable cardiac defibrillator (ICD) was implanted. LQT3 by genetic analysis was diagnosed at a later date. A strategy for ICD implantation in infants has not been established because few progress reports have been published. In infants, implantation of the epicardial leads through a lateral thoracotomy is common because indwelling of the transvenous endocardial leads is not possible. However, heart failure due to diastolic dysfunction and difficulty in lead removal resulting from adhesion are concerns. Therefore, we considered application of cardiac defibrillation between the ICD generator under the rectus abdominis muscle and the transvenous endocardial lead as a shock cord placed in the subcutaneous tissue of the back. Cardiac defibrillation for sustained VF was applied appropriately five times during five years after implantation without any complications, although the ICD generator required one exchange due to battery loss. We conclude that ICD implantation is safe and very useful, and strongly recommend ICD implantation for high risk LQTS patients with histories of VF and CPR, even at infancy.