Staff at AAHA-accredited hospital finds cure for potentially fatal canine heart ailment

Usually, scientists discover cures for human health conditions by testing them on animals. This time, it’s the other way around.

In a refreshing change of pace, a veterinary cardiologist and her colleagues have discovered a way to cure a rare but life-threatening heart arrhythmia in dogs by adapting a treatment pioneered in humans.

Kathy Wright, DVM, DACVIM (Cardiology and Internal Medicine), a veterinary cardiologist at MedVet Medical & Cancer Centers for Pets in Cincinnati, Ohio, AAHA’s 2016 Referral Practice of the Year, led the team (which also included colleagues from MedVet) that adapted the treatment. They conducted their study, funded in part through a grant from Morris Animal Foundation, from 1999 to 2017 and published their findings last fall.

Once considered relatively harmless, arrhythmias caused by atrioventricular accessory pathways (APs) are now known to cause rapid heart rhythms that can result in congestive heart failure or sudden death in dogs. Symptoms can include extreme fatigue and gastrointestinal distress, including lack of appetite and vomiting. Because these symptoms are similar to other common canine health problems, the condition is difficult to diagnose.

The minimally invasive technique, radiofrequency catheter ablation (RFCA), uses radio frequencies to disrupt the arrhythmia and allow the heart to resume normal function.

So far, veterinarians using RFCA have had a better than 95% success rate in treating dogs with this type of arrhythmia.

NEWStat contacted Wright to find out more about APs and RFCA.

NEWStat: An atrioventricular accessory pathway arrhythmia is considered rare, but just how rare is it?

Kathy Wright: The arrhythmia is rarely recognized and can be easily misdiagnosed due to the nonspecific nature of its clinical signs and their similarity with other conditions. We have identified the condition in 25 different breeds, with Labrador retrievers being significantly overrepresented. [That means] the true incidence is much higher than the reported cases, as these dogs are easily misdiagnosed as having gastrointestinal disease or dilated cardiomyopathy.

NEWStat: What inspired you to spend years pursuing a cure for a condition that, while underreported, still affects relatively few dogs?

KW: I first became passionate about helping [dogs with APs] during my rotating internship year. I was repeatedly presented with an adorable, young Labrador retriever who would come in every two to four weeks with tachycardia and congestive heart failure. No drugs would control him for any extended period, and I knew that a catheter-based technique had been developed in humans to address this issue. [And so] the lifelong passion began. I spent time learning in the electrophysiology laboratories of physicians at the University of Tennessee and Cincinnati Children’s Hospital. As a side note, while I would love it if I had invented radiofrequency catheter ablation, I assuredly did not. I merely adapted it and the mapping to our dog population.

NEWStat: Can RFCA be used to treat other kinds of tachyarrhythmia?

KW: RFCA can be used to treat a number of other tachyarrhythmias. We have treated several patients with atrial tachycardia as well. [More than] 100 procedures have been performed to date.

NEWStat: AP is controllable with medication. What are the benefits of treating it with RFCA instead?

KW: RFCA is a cure. Medications only control the rhythm and often, there are breakthroughs [e.g., if medication doses are missed or delayed] or side effects.

[In addition], heart muscle function can best recover when the abnormal rhythm’s substrate is eliminated and no more episodes occur. The totality of rhythm control is not gained by rhythm medications alone. Following a successful ablation, we can immediately discontinue a dog’s rhythm medications and often, all other medications, within a one- to six-month period.

[Plus], the ultimate cost of RFCA is less than that of lifelong medications with follow-up monitoring and potential emergency room visits for recurrence of the rapid heart rhythm.

NEWStat: Do you need to be a cardiac specialist to perform it? Or could general practice veterinarians perform it in their hospitals?

KW: Due to the sizable cost of the equipment (many hundreds of thousands of dollars) and subspecialized nature of the procedure, it would only be performed by veterinary cardiologists.

Photo credit: © iStock/NunoMonteiro

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