[Objective] Non-surgically related JET in heterotaxy syndrome has been rare, however if it occurs, such tachycardia make serious influence for morbidity and mortality in patients after Fontan type operation. Our aim of this study was to evaluate efficacy and risk of DDD pacemaker implantation and AVN modification during TCPC procedure. [Methods] A retrospective study was performed on the medical records and electro-physiologic studies.[Results] A total of 3 patients with asplenic heart were diagnosed as paradoxical JET prior to TCPC(Total Cavo-Pulmonary Connection) procedure. First onset of JET was from 9 day to 7 years of age. JT was terminated by combination of breath holding method, intravenous administration of adenosine triphosphate and verapamil in all 3 patients. On electro-physiologic studies, narrow QRS tachycardia with irregular RR interval was induced and terminated by ventricular pacing, and no retrograde conduction via atrio-ventricular node(AVN) and no twin atrio-ventricular node were observed in any patient. DDD pacemaker implantation and Cryo-ablation for AVN were performed during TCPC procedure in all 3 patients. Accelerated junctional rhythm occurred immediately after the operation and terminated by overdrive pacing in one patient. Transient complete atrio-ventricular block occurred in 2 patients. JT have never recurred after the operation in all patients with mean follow up of 27months.[Conclution] Electro physiologic study and their drug efficacy suggested that triggered activity was the mechanism of JET in patients with asplenic heart. DDD pacemaker implantation and AVN modification during TCPC procedure could be possible method for elimination of the JET.