Iatrogenic atrial septal defect with right-to-left shunt following atrial fibrillation ablation in a patient with arrhythmogenic right ventricular cardiomyopathy

Key Teaching Points • Transseptal puncture results in the formation of an iatrogenic atrial septal defect (ASD). In patients with right side–dominant cardiac pathologies (such as arrhythmogenic right ventricular cardiomyopathy), the transseptal pressure gradient from the right to left atrium promotes the formation of a right-to-left shunt across this ASD. • A right-to-left shunt across an iatrogenic ASD should be considered in these patients who present with dypsnea following their procedure, particularly if hypoxemic and cyanotic. • Potential strategies to minimize the risk of this complication in this population include avoiding “double sheathing” a single transeptal puncture, avoiding the use of larger sheaths, and assessing a right-to-left shunt at the conclusion of the case with echocardiography. • Patients who remain symptomatic of a right-to-left shunt should undergo ASD closure.