'Disappeared balloon': the trap of transseptal puncture for a large closure device of atrial septal defect-a case report.

Background: Several studies have demonstrated a notable increase in the incidence of atrial arrhythmias among individuals with atrial septal defect (ASD) occluder. Although the sequential dilation technique has been proposed as the mainstream technique for transseptal puncture with ASD occluder, it is associated with substantial risks and technical difficulties. Case summary: We report a patient who underwent catheter ablation for atrial fibrillation and had a large ASD occluder. A balloon was dislodged into the patient's right superior pulmonary vein (RSPV) during a transseptal puncture and was successfully captured. The most notable feature of this case was the dislodgement of the dilation balloon, which has not been reported previously. Discussion: Repeated and gradual dilation of the pathway with a pressure balloon is unavoidable during the establishment of the left atrial channel. It is not recommended to choose a coronary balloon and Run-through guidewire. Since only the tip of the coronary balloon is connected to the guide wire, it cannot stably guide the balloon through the puncture hole. When using over-the-wire balloon or peripheral vascular balloon, the balloon can stably attach to the guide wire as a whole, which allows movement along the puncture hole. The puncture hole can be safely expanded using a peripheral vascular balloon combined with a loach guidewire in subsequent expansion. In addition, it is important to avoid violent manipulation. After confirming the dislodgement of the balloon, it is imperative to remove it. Relying solely on oral anticoagulation may not sufficiently decrease the risk of thrombosis.