Atrial septal aneurysm mimicking cor triatriatum in a Cavalier King Charles dog

Abstract

Atrial septal aneurysm is a rare deformity of interatrial septum extending to changeable directions during cardiac cycle. A 9 year old Cavalier King Charles Spaniel referred to Small Animal Hospital with a history of acute onset of respiratoric distress and abdominal distension. Routin blood work, electrocardiography and thorax radiography were performed. Echocardiography revealed mitral valve disease and severe left atrial dilatation with an atrial septal aneurysm as a bulging of interatrial septum into the right atrium and nearly prolapsing into the tricuspid orifice. Color flow Doppler revealed a left-to-right shunt flow atrial septal defect. The dog died suddenly 2 weeks later. The owner declined postmortem examination. To the best of authors’ knowledge, this was the first report of atrial septal aneurysm with concomitant atrial septal defect in a dog. The purpose of this case report is to point out atrial septal aneurysm as the possible complication of mitral valve disease in a Cavalier King Charles Spaniel