An equine model of chronic atrial fibrillation: methodology.

The research describes the creation and features of a chronic atrial fibrillation model in horses using an adapted pacemaker. This model assists in studying the causes behind chronic atrial fibrillation in equines.

Creating the Model

• The researchers developed an experimental model of chronic atrial fibrillation in horses. This was achieved by using a dual-chamber pacemaker, specifically adapted for the purpose of this study and implanted within the horse while it was standing.
• The adapted pacemaker was designed to induce episodes of atrial fibrillation. This was accomplished by delivering a two-second burst of electrical stimuli (measured at 42 Hertz) whenever a natural heartbeat rhythm was detected.

Recording and Analysing Data

• To capture data during the induced episodes of atrial fibrillation, the researchers harnessed a surface electrocardiogram to record the intra-atrial electrogram. This allowed the team to determine the morphology, or shape and structure, of the atrial electrogram – essentially capturing how the atrial fibrillation episode manifested within the horse’s heart.
• Programmed electrical stimulation (PES) was used to assess different cardiac metrics. These included the atrial effective refractory period (AERP), an understanding of how the AERP adapted over time, the sinus node recovery time (SNRT), as well as a corrected measure of the SNRT. The researchers additionally studied the vulnerability to atrial fibrillation, the length of each atrial fibrillation cycle and the total duration of the atrial fibrillation episode.

Implications of the Study

• This research, through the development of an experimental model, facilitates a more thorough exploration of the causes behind chronic atrial fibrillation in horses.
• This model, and the data it yields, could potentially assist in better preventing, detecting and managing chronic atrial fibrillation in the future.