Cor triatriatum sinister with partial atrioventricular septal defect in a cat.

A 6-year-old female neutered Turkish Angora cat was referred due to tachypnoea. The patient was diagnosed with cardiomegaly at a local hospital during a health screening two years ago. Tachypnoea occurred one year ago. On physical examination, the patient presented with a respiratory rate of 72 breaths per minute and a systolic blood pressure of 70 mmHg. Thoracic radiographs revealed severe cardiomegaly, left atrium (LA) enlargement, right atrium (RA) enlargement, right ventricular enlargement, and dilation of pulmonary arteries and veins. An alveolar pattern was identified in the right and left cranial lung lobes. Echocardiography revealed a membrane that divided the LA into two chambers, a defect in the lower atrial septum, and elongation of anterior or posterior tricuspid valves (TV). However, septal TV was not observed. During systole, blood flow from LA to RA was confirmed through a defect in the atrial septum. During diastole, blood flow from LA to left ventricular was confirmed. These findings suggest cor triatriatum sinister (CTS) with partial atrioventricular septal defect (AVSD). This report describes echocardiographic diagnosis of CTS with partial AVSD in a cat.