Drinking just one highly caffeinated energy beverage at the gym set off a previously unnoticed heart problem in a British teen, according to a new report of his case.
 

After consuming the drink, the boy's heart began racing, so the 17-year-old went to the hospital, but his cardiovascular exam and chest X-rays looked normal. Doctors gave him drugs to slow his heart rate, but the medications instead caused his blood pressure to rise and an irregular heartbeat, the LiveScience Website reports.
 

A cardiologist then gave the teenager an electric shock, which improved the boy's symptoms and blood pressure. A follow-up electrocardiogram (EKG) revealed the problem: there was an extra electrical circuit in the boy's heart that stimulates the organ "in a way that is not the normal pattern," said Nicholas Skipitaris, M.D., the director of electrophysiology at Lenox Hill Hospital in New York City, who was not involved in the boy's case.
 

In some people with the condition, the extra circuit is so weak that the condition doesn't cause any real problems, but stimulants like caffeine can drive up their heart rate. People who do have problems usually discover they have the condition during adolescence, and have it treated before adulthood, Dr. Skipitaris said.
 

About 1 to 3 people per 1,000 people have the syndrome. Less than 0.6 percent of people with the syndrome are at risk of sudden cardiac death, the study reported.
 

The case study was published in the journal BMJ Case Reports.