Atrial Fib Explained As the experts at the Tufts Cummings School of Veterinary
Medicine explicate on the school’s web site, “The heart is the most important muscle in the (horse’s) body—without the heart, none of the other muscles would be able to get the fuel that they need—oxygen. How does the heart know when and how to pump the blood to the body? It receives electrical signals that tell it, in a very rhythmical and predictable fashion, when to contract, and thus pump blood.” Dr. Elizabeth Callahan, from the Veterinary Medical Center
in Easton, Maryland, had explained to Wendy that when the heart beats, the atria—the top chambers of the heart— contract and push blood into the lower chambers called the ventricles. With atrial fibrillation, that smooth sequence falls apart and chambers are contracted without blood to push through. “It is no longer a coordinated heartbeat and it is not an efficient flow of blood,” she says, describing that the more physical stress a horse is under, the more difficult it will be for that horse to perform. It stands to reason, she says, that an upper-level performance horse developing atrial fibrillation would have tremendous difficulty continuing at that level.
Home Again Susan decided she was not comfortable selling Pilot and
began to investigate the options for donating him to a college or university, where he could stay in work without having to function at a level that would strain his heart. “I just wanted to do the right thing for him,” Susan explains. “He’s just such a great horse!” For Wendy, the news of Pilot’s heart condition and
potential donation was tugging at her own heart. “I did some soul searching, appealed to my ever-understanding husband, and eventually we worked it out that I could purchase Pilot and bring him home. So in the summer of 2012 he came back to our farm in Maryland,” Wendy recounts. She was even able to take him for a short ride since many horses with atrial fib are okay for light work. But Pilot’s condition wasn’t that straight forward as Wendy would soon discover. Wendy’s veterinarian, the Veterinary Medical Center’s Dr.
Callahan, evaluated Pilot soon after his return. She had bad news to report: his heart rate was both irregular and very high, even when simply standing in his stall. That meant that if nothing were done he should not be ridden again and would need to be handled with extreme care. Then Dr. Callahan presented a potential solution: a
procedure called “cardioversion” (or simply “conversion”) that could help Pilot. Wendy was concerned about the risks involved, which can include colic, founder, collapse, swelling around the throat and other abnormal heart rhythms.
Testing and Treatment Next Wendy and her husband Marty took Pilot to the
University of Pennsylvania’s famous New Bolton Center for testing. It was a stressful time for Wendy. “It was a two-hour drive. Then an all-day stay before driving home again,” she
Wendy is reunited with Pilot last October before the conversion. Warmbloods Today 21
JJ Tate and Pilot schooling in 2007.
recalls. “Pilot was such a good boy, standing still for so many monitors, a heart rate check, a blood pressure cuff on his tail and many ‘sticks and jabs.’ I could tell the doctors liked him and I was so hopeful. But I also couldn’t stop worrying. Was this how my firstborn was going to end his career? Retired at age 13? How far should we go with conversion? While it is not the most expensive procedure, it is still not that affordable.” During testing, working on the lunge line and wearing a
heart monitor, Pilot’s heart rate raced past the upper limits of a healthy heart. This was a worry because, especially combined with an irregular beat, a heart beating too fast put Pilot in danger of imminent collapse. Dr. Callahan explained to Wendy that conversion is
a relatively common procedure with race horses and is becoming more common with sport horses as well. She
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