EXPRESS: A Complex Aortic Coarctation with Ventricular Septal Defect and Patent Ductus Arteriosus in a Kitten

Case summary: A 6-day-old female domestic shorthair kitten weighing 140 g was presented with poor nursing and severe cardiogenic pulmonary oedema. Initial echocardiography revealed bilateral atrial enlargement, a membranous ventricular septal defect (VSD), and aortic narrowing. Follow-up assessment demonstrated progression of cardiomegaly and identification of a patent ductus arteriosus (PDA). On day 48, multidetector CT confirmed a focal, severe narrowing of the aorta between the origin of the left subclavian artery and the insertion of the ductus arteriosus, consistent with aortic coarctation with concurrent VSD and PDA. Owing to the extremely low birth weight, surgical intervention was not feasible, and medical management was continued. The kitten developed transient atrial fibrillation on day 72, which resolved with diltiazem. Despite comprehensive medical therapy, refractory congestive heart failure recurred, and the kitten died on day 160. Postmortem examination confirmed focal aortic narrowing adjacent to a cylindrical PDA, marked biatrial dilatation, biventricular concentric hypertrophy, a membranous VSD and a right atrial mural thrombus. Histopathology of the pulmonary artery and PDA demonstrated elastic artery-like remodelling, consistent with chronic haemodynamic loading and secondary pulmonary hypertension. Relevance and novel information: aortic coarctation is an exceptionally rare congenital cardiovascular anomaly in cats. This report describes the clinical presentation and detailed postmortem characterisation of aortic coarctation with concurrent VSD and PDA in a kitten, highlights the diagnostic utility of advanced antemortem imaging, and illustrates the limitations of medical management in the presence of complex structural disease.