cardiac ablation in a horse

Belgian veterinarians have completed the first cardiac ablation in a horse ever performed. The procedure, used to correct irregular heartbeats, was a success.

Diamant, a 5-year-old Norwegian show jumper, came through the four-hour operation with no difficulties.

“It’s very exciting to see that there’s now a way to offer this therapeutic treatment—which has shown great success in human medicine—to equine patients, while creating many new opportunities for the future of equine cardiac medicine,” said Gunther van Loon, DVM, PhD, Dip ECEIM, Assoc. Member ECVDI, president of the Belgian Equine Practitioners Society (BEPS), head of the Equine Cardioteam, and professor in Ghent University’s Faculty of Veterinary Medicine, in Belgium.

Cardiac ablation involves placing tiny catheters into the heart via the jugular vein, which surgeons access through four small incisions in the neck. They use the catheters to heat the precise part of the inside of the heart wall—usually a space of only about a half-centimeter in diameter—that’s malfunctioning and causing the irregular beats. Heating it essentially disarms it so it can no longer send the wrong electrical signals that cause arrhythmia.

Precise catheter placement in such cases is critical, van Loon said. One slight error when working with the heart could lead to disaster. That’s why cardiac ablation procedures in human patients are guided by MRI, CT scan, and radiography. Cardiologists use a method called mapping to find the faulty wall area, which involves creating an “electrical activity map” of the heart in three dimensions using electrically sensitive catheters. Hearts create their own electricity to function, beat, and pump blood in perfect rhythm. But if the electrical “wiring” is faulty, arrhythmias and other cardiac dysfunction can occur.

Mapping, guiding catheters into, and performing ablation in the 300-gram (10-ounce) human heart under MRI or CT are complex procedures to begin with, van Loon said. But carrying out those tasks in the 3-kilogram (7-pound) equine heart, nestled deep in the 600-kilogram (1,350-pound) equine body, presents road-blocking challenges.

“You just can’t fit that huge body into the imaging machines,” he said.

Van Loon and the Equine Cardioteam—made up of veterinary and human medicine specialists—were undeterred by that road block, however. Through months of research, trials, and practice, they found a way around it, mastering both mapping and catheter placement under ultrasound guidance instead.

And with that knowledge and experience, they attempted the last step—the actual cardiac ablation procedure (view a video of it below)—under ultrasound guidance, as well. It worked.

“We had so many questions beforehand,” van Loon said. “Will we find the spot? Will we be able to reach it through those long veins? Will the procedure be technically feasible? But in the end, the answer to all those questions was yes. And as soon as we performed the ablation, Diamant’s arrhythmia stopped, right then and there. The effect was immediate.”

Diamant had had a successful career as a show jumper in Norway, van Loon said. But at some point he “seemed to lose his spark,” he said. Through attentive observation Diamant’s rider picked up on subtle signs of cardiac disease, and veterinary evaluations led to a diagnosis of arrhythmia.

Despite repeated (and successful) electrical shock treatments to the heart, Diamant’s arrhythmia continued to recur. He had ongoing reduced performance and seemed generally “off,” van Loon said.

“He was a real challenge,” he said. “His arrhythmia would come back surprisingly quickly after an electroshock treatment and despite medications. He really needed the ablation procedure that at the time was only available to humans.”

Three months after his pioneering ablation procedure, Diamant continues to do well and is returning to work, van Loon.

Because of this success, van Loon and the Equine Cardioteam plan to continue their work in this field to fine-tune the procedure and make it more available to other horses in need of ablation, he said.

“Most horse owners, especially if their horses are working at lower or medium levels, wouldn’t notice signs of arrhythmias, and many horses can function perfectly well with them at those levels,” said van Loon. “But in certain cases—particularly in horses of a high level of sport—the arrhythmia can become dangerous and even lead to collapse. Our hope is that now that this procedure is becoming accessible to horses, these cases of reduced performance and associated risks can be prevented.”