Reversible third-degree atrioventricular block in a Poodle-Toy with degenerative mitral valve disease and pyometra

Abstract

Third degree atrioventricular block is a severe arrhythmia, being the most common indication for artificial cardiac pacing in dogs. Spontaneous reversion to normal sinus rhythm is very rare or exceptional. A 12-year-old Poodle-Toy was referred because of history of abdominal enlargement, anorexia, vomiting and weakness. Abdominal ultrasonography revealed large pyometra. Then, a six-lead electrocardiogram presented third-degree atrioventricular block, while transthoracic Doppler echocardiography showed myxomatous mitral valve disease, presence of mitral, tricuspid and aortic regurgitation, accompanied by mitral and tricuspid diastolic insufficiency. Two days after the ovariohysterectomy, a new electrocardiogram revealed spontaneous reversal to the sinus rhythm, while the diastolic reflux of mitral and tricuspid valves disappeared. The patient showed rapid clinical amelioration and eight months after surgery was still alive, on treatment for heart failure. As far as we know, this is the first canine case of third-degree heart block, secondary to endocardiosis and pyometra, which was spontaneously reverted to sinus rhythm after surgery.

Keywords

• cardiac arrhythmia
• degenerative mitral valve disease
• diastolic mitral reflux
• dog
• pyometra
• third-degree heart block