A 9-year-old boy in Turkey opened wide for a big bite of a tasty hot dog, but had no idea the simple act might almost kill him.

According to a report from doctors in Istanbul, the bite triggered a near-fatal heart event that also revealed a hidden health problem.

As reported Sept. 6 in Pediatrics, the boy's heart stopped beating and he fainted soon after biting into a frankfurter at school.

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Luckily, help arrived soon and he was "defibrillated and resuscitated for 30 minutes," said a team led by Dr. Isa Ozyilmaz. He's a pediatric cardiologist at Istanbul's Mehmet Akif Ersoy Thoracic and Cardiovascular Surgery Training and Research Hospital.

First sent to a pediatric ICU, the boy was forwarded to Ozyilmaz' clinic because of "suspicious" heart rhythm readings, the researchers explained.

After further tests, it was discovered that the boy had a rare but potentially fatal heart rhythm condition called Brugada syndrome. To help control it, he now has an implanted cardiac defibrillator.

"Brugada syndrome is a relatively rare condition that affects the [electrical] conduction system of the heart," explained Dr. Sophia Jan, a pediatric specialist at Cohen Children's Medical Center in New Hyde Park, N.Y., who has reviewed the case.

"The biggest danger of Brugada syndrome is that it can cause the heart to develop dangerous irregular rhythms that can lead to sudden death," she said.

But how could taking a big bite of a hot dog "set off" the syndrome? As Jan explained, the key lies in a bit of neuro-anatomy called the vagus nerve.

"The vagus nerve is a long nerve that travels from the brain down to the heart and into our gut," she said. "It controls, among many things, our heart rate -- we can actually cause our heart rate to slow down by activating our vagus nerve, which happens when we bear down [for example, in a bowel movement] or when we try to exhale while pinching our nose and closing our mouth."

But there are other ways to activate the nerve, as well.

"When this young boy with Brugada syndrome took a large bite of a hot dog, he likely gagged slightly on the hot dog, causing activation of his vagus nerve, and consequently triggering an irregular rhythm of his heart," Jan explained.

She noted that Brugada syndrome tends to run in families, so the Istanbul team brought the boy's parents and brother in for heart tests as well.

While the mother and father showed no signs of the condition, the brother "was also diagnosed with Brugada syndrome," the Turkish researchers noted. Because the brother hadn't yet displayed symptoms he was not treated.

However, the 9-year-old and his brother have now been advised to avoid a number of activities as they grow older that could trigger the syndrome. These include drinking to excess, having a high fever, avoiding certain medicines and -- not surprisingly -- taking big bites from "larger-size food items."