Abstract
Current leadless pacemaker (LP) systems, which have been developed and used in patients with normal cardiac anatomy, are rare and technically even more challenging to implant in patients with congenital heart diseases, especially with univentricular physiology and Fontan palliation. We report two cases of percutaneous LP implantation in an adult and a child, respectively, highlighting the unconventional approaches, different challenges, and use of multimodality imaging in patients who underwent a Fontan operation.