Transthoracic echocardiography in the apical 4-chamber view on admission revealed a huge dissecting cystic mass-like aneurysm (5.0×3.5 cm) in the interventricular septum from the basal to mid-septal level filled with a focal thrombus (arrow). LA: left atrium, LV: left ventricle, RA: right atrium, RV: right ventricle.