Background-Catheter ablation of left-sided atrial arrhythmias generally is performed using a transfemoral venous approach through the inferior vena cava (IVC). In this report, we assessed the feasibility of a percutaneous transhepatic approach to ablation of left-sided atrial arrhythmias in 2 patients with interruption of the IVC. Methods and Results-Patient 1 had atrial flutter in the setting of complex congenital heart disease and prior Fontan for univentricular physiology and a single atrium. Patient 2 had atrial fibrillation. Percutaneous hepatic vein access was obtained with ultrasound and fluoroscopic guidance. Transseptal catheterization was performed in patient 2. After the procedure, the hepatic tract in patient 1 was cauterized using a bipolar radiofrequency catheter, and an Amplatzer vascular plug was used in patient 2 to obtain hemostasis. Percutaneous hepatic vein access was achieved without complications. After electroanatomical mapping, a linear lesion was placed between the single atrioventricular valve and the confluence of the hepatic veins in patient 1; this terminated the flutter, and bidirectional block was achieved. In patient 2, the pulmonary veins were electrically isolated using an extraostial approach, isolating the ipsilateral veins in pairs. Additionally, ablation of right-side atrial flutter was achieved by obtaining bidirectional block across a linear lesion between the tricuspid valve and confluence of the hepatic veins. Hemostasis of the transhepatic tract was attained in both patients. Conclusions-In