A case of coronary sinus ostium atresia misdiagnosed as patent foramen ovale

A 15-year-old male patient presented with a three-year history of recurrent dizziness and headaches and was initially diagnosed with patent foramen ovale (PFO). A transcatheter closure procedure was planned and conducted under general anesthesia, utilizing ultrasound guidance through the femoral vein. Pre-admission echocardiography confirmed the presence of a PFO. However, further investigation with transesophageal echocardiography (TEE) and contrast echocardiography, both performed under general anesthesia, revealed that the observed atrial septal anomaly was not a PFO. Instead, real-time TEE identified it as the left atrial opening of the coronary vein. Subsequent detailed TEE tracking confirmed a rare case of coronary sinus ostium atresia (CSOA) with left atrial reflux of the coronary vein, leading to a significant revision of the initial diagnosis and planned treatment.