A teenager from England went to the hospital for back pain – and ended up being treated for a rare heart condition instead.

Cassie Thorton’s heart was beating up to 200 times a minute, which is three-times the norm, the Evening Standard reported.

The 15-year-old from Bristol, England, was rushed to the hospital after her mother found a lump at the base of her spine. She thought it was meningitis, but after doctors measured her heart rate, they found it was through the roof.

“They thought the machine was broken,” Cassie’s mother told the newspaper. But when the nurse got another one, Cassie's heart rate was jumping around up to 208 beats a minute.”

Doctors diagnosed the teenager with permanent junctional reciprocating tachycardia – a condition that causes the heart to beat too quickly or with an irregular pattern and may cause sudden death, according to the report.

After several attempts to slow her heart rate, doctors opted for a minimally invasive procedure called radio frequency ablation. The procedure helps doctors place a catheter at the exact site inside the heart where cells give off electrical signals that stimulate abnormal heart rhythm, according to the American Heart Association.

A painless radio frequency energy is then transmitted to the pathway which carefully destroys selected heart muscle cells. This stops the area from conducting the extra impulses that causes rapid heartbeats, AHA said on its Web site. It’s widely used and is the preferred treatment for this type of condition.

The procedure, done on May 8, was a success, and Cassie has since been given a clean bill of health.

“The doctors said she was now 98 percent repaired, which is about as good as it gets.” Cassie’s mother told the paper.

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