KEY TEACHING POINTS

•Radiofrequency ablation of neonatal flutter after failure of all other treatment options is an option but rarely necessary. Use of a 5Fr ablation catheter and a diagnostic transesophageal catheter limits vascular damage. •Use of a 3-dimensional system keeps radiation to a minimum and allows an approach using only 1 intravascular catheter. System resolution is just adequate for neonatal body size. •Bidirectional block over the cavotricuspid isthmus is the gold standard for proving successful ablation and a line without gaps. In the neonatal setting, the transesophageal catheter did not reliably exclude a gap. A multipolar 5Fr catheter properly placed along the tricuspid valve can be used instead.