Innovations and Hurdles in Equine Arrhythmia Treatment: A 3D Mapping and Ablation Perspective

Presentation Description / Summary: 3D electro-anatomical mapping (3DEAM) of the heart is a technique that creates a detailed, real-time visualization of both cardiac anatomy and electrical activation, enabling precise diagnosis and treatment of arrhythmias by catheter ablation. Challenges for application in horses include the need of a table without magnetic interference, limited maximal chest diameter, a thicker myocardial wall, limited catheter length, catheter design (hampering to apply sufficient contact force in a large heart) and the limitations of fluoroscopy. Despite these challenges, 3DEAM has already demonstrated important clinical value. In three horses with a high burden of premature atrial complexes, 3DEAM identified the origin of ectopy at the right atrial free wall and radiofrequency ablation successfully eliminated the ectopic focus in one horse. 3DEAM has been used most successfully in horses with sustained atrial tachycardia, or atrial fibrillation preceded by atrial tachycardia, consistently revealing a ‘typical atrial flutter’ circuit around a central area of conduction block in the caudal vena cava in almost all horses. Ablation of the slow conducting areas, thereby isolating the caudal vena cava, proved to be highly effective in preventing recurrence. Little information is available on accessory pathways in horses. However, 3DEAM successfully localized both a right- and left-sided accessory pathway, which was associated with ventricular pre-excitation and orthodromic atrioventricular reentry tachycardia, respectively. Radiofrequency ablation successfully eliminated accessory pathway conduction. So far, ablation of atrial fibrillation is still very challenging and the technique has not been applied to ventricular arrhythmias yet.