# Left-to-Left Acquired Cardiac Shunt: Aorto-Left Atrial Fistula Due to Aortic Infective Endocarditis in a Dog

## TL;DR

A 7-year-old dog developed a rare heart condition involving infection and a fistula between the aorta and left atrium, leading to sudden death.

## Contribution

This case report documents a rare aorto-left atrial fistula caused by aortic infective endocarditis in a dog.

## Key findings

- Echocardiography revealed hyperechoic changes and a retrograde turbulent jet from the left ventricle to the left atrium.
- Postmortem examination confirmed infective aortic endocarditis with a paravalvular abscess and a fistula.
- The dog's condition was fatal despite intensive care treatment.

## Abstract

Infective endocarditis represents a rare, acquired condition in animals, but also in humans, that typically involves one of the heart valves and mainly affecting the mitral and aortic valves in dogs. This report describes the clinical signs, the diagnostic approach and the postmortem investigations of a case confirmed with infective endocarditis at the level of the aortic valve but also the presence of a main consequence of the disease, represented by the development of paravalvular abscesses and subsequent fistulous tracts between heart chambers.

Infective endocarditis is a severe but rarely diagnosed disease, characterized by the presence of bacterial infection at the level of the cardiac valves. Although the incidence of the disease is very low, the consequences are severe and the prognosis is very poor, outlining a high mortality rate among cases. The present report highlights the case of a 7-year-old dog presented with abrupt changes in the respiratory pattern, obtunded and in lateral recumbency. The physical examination of the patient revealed fever and a IV/VI systolic heart murmur, with the point of maximal intensity on the left hemithorax. Echocardiography identified hyperechoic and cavitary changes beneath the aortic valves and a retrograde turbulent jet originating in the left ventricle outflow tract communicating with the left atrium through a rupture in the aortomitral intervalvular wall. Because of very unstable hemodynamic changes, the dog suddenly died despite the initiation of intensive care supportive treatment, and the postmortem evaluation of the heart confirms the suspicion of infective aortic endocarditis with the development of a paravalvular abscess and an aorto-left atrial fistula.