Discrimination between QRS and T Waves Using a Right Parasternal Lead for S-ICD in a Patient with a Single Ventricle

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is a useful option for patients with a single ventricle (SV) in which transvenous leads are contraindicated because of intracardiac shunts. We report a case in which a right parasternal lead placement was indicated for an S-ICD in a resuscitated patient with an SV. There were significant changes in the magnitude of R to T waves ratio in the right compared to the left parasternal lead position. Screening in the right parasternal position is effective for selecting appropriate patients with congenital heart disease for S-ICD implantations.