Left Atrial Thrombus Due to Transseptal Catheterization Simulating Solid Mass of Right Atrium

Background Transseptal catheterization has been popularized through ongoing advances in percutaneous procedures, but related complications are known to occur. Case presentation A 72 year-old female was admitted with left-sided weakness. In the course of various exams, a rounded and smooth-surfaced solid mass of right atrium was identified. However, a septal aneurysm associated with left atrial mural thrombus was evident intraoperatively. Given that percutaneous transseptal mitral valvotomy had been done 7 years previously, a causal relationship is likely. Conclusions Prior cardiac intervention should be considered in patients presenting with mass lesions of interatrial septum.