Claire Hazenberg braved nearly eight hours of surgery while wide awake.

A young Brisbane heart patient has undergone a life-changing medical procedure to stop debilitating blackouts.

Just a few months ago, heart patient, Claire Hazenberg couldn't even take a stroll without fear of collapsing.

For nearly eight hours Claire Hazenberg was awake on the operating table while doctors performed the surgery.

"It honestly feels like it's about to jump out of your chest, and it's the most terrifying feeling," Claire said.

Claire's heart would race from a normal 60-70 beats per minute up to 260 beats.

Her blood pressure would drop and she'd black out.

"It just got out of control and it was the only thing on my mind," she said.

"I couldn't think about school, I couldn't think about work, it was just horrible."

For more than 18 months Claire lived with the debilitating condition known as tachycardia, before she had life-changing surgery.

Using state-of-the-art equipment at St Andrew's Hospital, cardiologist Dr Paul Martin guided two wires through a vein in Claire's leg to her heart.

High frequency energy was then sent into the muscle to destroy abnormal cells.

"What the catheters do is allow us to pinpoint the spot that's firing off the short circuit that she's got, and then we can burn and get rid of that short circuit," Dr Martin said.

"I said I was happy to do the study if she was happy to be awake and she agreed, which was incredibly brave of her."

Claire couldn't be sedated because that would have subdued the tachycardia and made the condition more difficult to treat, so she was awake for the entire eight hour operation.

"It was like a chainsaw and fireworks and fire all mixed in just killing my heart," she said.

While the pain was tough to bear she says listening to her doctor's music was just as hard.

"It was nice 80s, 70s rock, never really heard of it in my life. It was really painful, probably more painful than the surgery."