Iatrogenic Atrial Septal Defect Causing Position-Dependent Hypoxemia

A 70-year-old woman, who had received mechanical aortic and mitral valve replacement for rheumatic valvular disease and implanted cardiac defibrillator (ICD) implantation for ventricular arrhythmia, underwent radiofrequency catheter ablation for symptomatic atrial fibrillation (AF). During the