[A case of two-chambered left ventricle with echoes of an abnormal floating mass].

A case of a two-chambered left ventricle with an abnormal floating mass was reported. A 13-year-old boy was admitted to our hospital because of a grade III/VI transsystolic apical murmur. Chest radiography showed mild cardiomegaly. The electrocardiogram showed QS patterns in leads V1-V3, and left ventricular high voltage with wide QRS complexes. A two-dimensional echocardiogram revealed two chambers divided by the septum in the left ventricle, and a mass floating in the apical chamber. A levogram showed the double chambered left ventricle incompatible with the findings of echocardiography. The walls of the accessory chamber and the septum were hypokinetic, but not dyskinetic. Coronary arteriograms were unremarkable. At surgery, tangled trabeculae carneae and chordae tendineae were observed on the apical surface of the septum. The accessory chamber communicated freely with the main chamber through an orifice with a diameter of 1.5 cm. No other congenital malformations were found. Microscopic examination of the accessory chamber wall showed the thickened endocardium and hypertrophic myocardial fibers, and there was no area of fibrosis.