Implantation of transvenous leads for a permanent cardiac pacing system usually requires the absence of intracardiac shunts. We report the case of an asymptomatic atrial septal defect in an 11-year-old boy who required permanent pacing. We implanted an atrial septal defect closure (Clamshell) device prior to implantation of transvenous leads. This new device makes transvenous implantation possible and may reduce the risk of stroke in patients with these anomalies.