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Lend an Ear: New Non-Invasive Approach Targets Errant Heart Rhythm

Wednesday, July 1, 2015 - Campus News -
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Have you ever experienced sudden lightheadedness, shortness of breath or heart palpitations?  An irregular heart rhythm may be to blame.

It’s a condition known as atrial fibrillation, and more than 2.3 million people in this country have some form of it. Now, researchers at the University of Oklahoma Health Sciences Center have shown a non-invasive treatment that delivers low-level electrical stimulation through a part of the ear can suppress atrial fibrillation.

Atrial fibrillation is a condition in which the upper chambers of the heart lose their normal rhythm and beat chaotically.

“Atrial fibrillation affects a lot of people – up to 10 percent of the population. And the older people get, the more common atrial fibrillation is,” said lead researcher Stavros Stavrakis, M.D., Ph.D., with the OU College of Medicine’s Heart Rhythm Institute.

The study involved patients with a specific type of atrial fibrillation in which the errant rhythm occurs occasionally and then stops. OU researchers found that low-level electrical stimulation delivered by way of a part of the ear known as the tragus can suppress the irregular heart rhythm. The tragus is that little bump of cartilage located at the front of the outer ear.  It doesn't really do a lot, but it appears to provide a pathway to a specific nerve in the brain stem that appears to exercise some control over atrial fibrillation. 

“We found that the time that people were in atrial fibrillation was decreased by about 50 percent after stimulating the tragus for one hour compared to those in the study who did not receive the low-level electrical stimulation,” said Stavrakis.

In previous laboratory studies, Stavrakis and his team showed they could effectively halt atrial fibrillation with low-level electrical signaling applied directly to the nerve. 

“So we were trying to find a way to non-invasively stimulate the nerve, in other words, without surgery,” he explained. “We found a study in which researchers had systematically stimulated different parts of the ear and were able to elicit a response in the brain. So we tried it first in the laboratory to see if we could stimulate the nerve through an electrical signal applied to that part of the ear called the tragus, and it worked nicely.”

The next step involved a study of 40 patients referred to the electrophysiology lab at OU Medicine. Under general anesthesia, half received low-level electrical stimulation of the right ear through a small metal clip attached to the tragus. The other half had the device attached but did not receive the treatment.

The patients who received the low-level electrical stimulation saw a significant decrease in the amount of time in atrial fibrillation. In the control group, by contrast, the time in atrial fibrillation actually increased slightly. 

“We also found it was more difficult to produce atrial fibrillation after treatment,” Stavrakis said. 

He called the results promising and said the next step is to evaluate the treatment approach in patients with this type of atrial fibrillation while awake, since this initial study involved patients with acute atrial fibrillation who were under anesthesia.

 The new study involving treatment while awake has recently received funding from the American Heart Association, and Stavrakis said they hope to begin that research soon.

“A preventive approach is the goal. So we hope to next evaluate this approach in patients who could do this at home using an electrical stimulation device similar to those used for pain management,” he said.

The approach is not only non-invasive, it also is not painful. Stavrakis said that’s because the level of electrical stimulation needed to slow the heart rate is well below the threshold that produces discomfort.

“We anticipate that the patients undergoing treatment at home would not even feel the stimulation,” he said.

The research produced another interesting discovery. Stavrakis and his team also drew blood in patients, measured markers in the blood known as inflammatory cytokines and found that low-level electrical stimulation reduced those markers, thereby potentially inhibiting inflammation within the body.  

“We think that this is important because it means this technology and treatment method also may be useful in treating other diseases associated with inflammation like rheumatoid arthritis,” Stavrakis said.

The research is published in the Journal of the American College of Cardiology.

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