Intracardiac overdrive pacing as a treatment of atrial flutter in a horse.

This research presents a case where a horse suffering from atrial fibrillation, treated initially with quinidine sulphate but resulting in atrial flutter and toxicity, was successfully treated with a rapid atrial pacing technique restoring its normal sinus rhythm. The subject horse was found to be in a healthy state even a year after treatment.

Background

• The subject of the study was a five-year-old warmblood mare suffering from atrial fibrillation, a prevalent and serious irregular heart rhythm disorder in horses.
• The mare was initially treated with quinidine sulphate, a medication commonly used to treat atrial fibrillation in horses.

Challenge

• Instead of helping, the initial treatment with quinidine sulphate changed the mare’s atrial rhythm to atrial flutter, another type of abnormal heart rhythm.
• The medicine also had toxic effects, prompting the researchers to discontinue its use.

Pacing Therapy

• Seven months following the shift in rhythm to atrial flutter, the researchers tried a different treatment approach – rapid atrial pacing method.
• Also known as overdrive pacing, this technique involves sending electrical impulses to the heart through a pacemaker at a rate faster than the heart’s natural rhythm.

Outcome

• This treatment approach successfully restored the mare’s heart back to its normal sinus rhythm.
• One year post-treatment, the mare still maintained its sinus rhythm, showing the long-term effectiveness of the rapid atrial pacing therapy.
• Notably, the horse was even brought back into training, indicating its good health and recovery.

Significance

• This study’s results suggest that rapid atrial pacing can be an effective treatment for horses suffering from atrial flutter, particularly those who experience side effects from conventional medication such as quinidine sulphate.
• It demonstrates the potential of this therapy in restoring and maintaining a normal heart rhythm in horses, raising prospects for its broader application and further investigation.