Work

Treatment of a concealed accessory pathway by radiofrequency catheter ablation in a horse

Year: 2026

Type: article

Abstract: BACKGROUND: Accessory pathways (APs) are myocardial bundles directly connecting the atria and the ventricles, bypassing the atrioventricular node-His-Purkinje system. Retrograde AP conduction in horses can result in orthodromic atrioventricular re-entry tachycardia or bradycardia. Radiofrequency catheter ablation (RFCA) can provide a permanent treatment by eliminating the retrograde conducting AP, but was previously unsuccessful in one case. OBJECTIVES: To report the use of three-dimensional electro-anatomical mapping (3D EAM) to identify a concealed AP and treatment by RFCA in a horse. STUDY DESIGN: Retrospective case report. CASE DESCRIPTION: An irregular heart rhythm was detected in a 4-year-old, 518 kg Paint mare as an incidental finding. Frequent atrial depolarisations were identified in the ST segment with a fixed coupling interval to the preceding QRS complex on the ECG. A differential diagnosis of frequent premature atrial complexes displayed as bigeminy or a retrograde conduction along an AP was made. The presence of a retrograde conducting AP was confirmed by ventricular pacing, which resulted in 1:1 ventriculo-atrial activation. Three-dimensional EAM revealed the earliest atrial activation and thereby the atrial insertion of the AP in the caudal left atrium. Subsequent RFCA at 40 W eliminated AP conduction. MAIN LIMITATIONS: Single case report. CONCLUSIONS: This case report describes the identification of an AP by 3D EAM and the first successful permanent treatment of a retrograde conducting AP by RFCA in an adult horse.

Source: Equine Veterinary Journal

DOI: 10.1002/evj.70361