Key result
Infiltrative intracardiac paraganglioma causes complete AV block, heart failure, and sudden death.
Why the study?
Intracardiac neoplasia is a rare differential diagnosis for atrioventricular conduction disturbances in older dogs.
Case Report (n=1)
No
Intracardiac neoplasia, though rare, should be considered as a differential diagnosis for atrioventricular conduction block in older dogs.
Cardiac masses may underlie complete AV block in dogs; extends sparse case reports but leaves management questions open.
A 14-year-old, 6-kg dog was referred for lethargy, exercise intolerance, and syncope. Electrocardiography revealed complete atrioventricular block with a narrow QRS escape rhythm at 40 bpm. Echocardiography identified a solitary mass involving the interatrial septum with extension into the interventricular septum, associated with valvular regurgitation and chamber enlargement. Despite medical management of congestive heart failure, the dog died suddenly 10 days later. Necropsy revealed a large mass infiltrating the interatrial and atrioventricular septa, including Koch’s triangle and the septal vestibule. Histopathology and immunohistochemistry supported the diagnosis of a intracardiac paraganglioma exhibiting locally invasive histological features. This case describes an intracardiac paraganglioma associate with an AV block and illustrates that intracardiac neoplasia is a rare differential diagnosis for atrioventricular conduction disturbances in older dogs.
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Corda et al. (2026) conducted a case report in Third degree atrioventricular block secondary to intracardiac paraganglioma (n=1). Intracardiac paraganglioma was evaluated. An intracardiac paraganglioma infiltrating the interatrial and atrioventricular septa caused complete atrioventricular block and congestive heart failure, resulting in sudden death in a 14-year-old dog.
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