EXPRESS: Echocardiographic description of pulmonary vein stenosis in a cat with AVSD

Case summary A 2.5-year-old intact female British Shorthair cat was referred for cardiology evaluation due to intermittent panting and a heart murmur identified on cardiac auscultation before elective surgery. Physical examination revealed a left parasternal grade II/VI systolic murmur without arrhythmia. Thoracic radiographs showed cardiomegaly without pulmonary infiltration. The echocardiography was prompted by auscultation, history, and radiological findings. Transthoracic echocardiography demonstrated marked right atrial enlargement and eccentric hypertrophy of the right ventricle. Echocardiography revealed a partial atrioventricular septal defect characterised by a large ostium primum defect (0.79 cm) and an anterior mitral valve cleft, resulting in a left-to-right shunt (estimated Qp/Qs ≈ 2.2). Doppler interrogation of the left pulmonary vein entering the lateral wall of the left atrium demonstrated focal turbulence and increased peak velocity (1.08 m/s), corresponding to a pressure gradient of approximately 4.7 mmHg, findings consistent with suspected unilateral pulmonary vein stenosis. Tricuspid regurgitation velocity (2.2 m/s) did not reflect increased afterload. Elective surgery was postponed owing to uncertainty regarding peri-anaesthetic haemodynamic risk. Medical treatment with enalapril and clopidogrel was initiated. At 9-month follow-up, the cat remained clinically stable and echocardiographic findings were unchanged. Relevance and novel information Pulmonary vein stenosis is rarely reported in cats. This report describes the concurrent presence of partial atrioventricular septal defect and suspected unilateral pulmonary vein stenosis. These findings highlight the detection of a congenital heart defect in a young cat, despite the low-grade murmur.