Greater Western Sydney young gun Jacob Hopper has revealed he underwent heart surgery in the off-season.

In an interview with The Daily Telegraph, the Rising Star nominee opened up about the heart condition he has suffered since childhood.

Supraventricular tachycardia, known as SVT, is a condition where an abnormally fast heart rate is caused by improper electrical activity. It can happen on random occasions, leaving the person unable to complete basic exercises.

Hopper said he had a few scary incidents before Christmas.

“My heart rate went crazy,” Hopper said.

“It went up to 240(bpm). The nerve impulse goes around in circles and my heart races and to walk 50 metres I’d be stuffed. It wasn’t ideal at all.”

Hopper said the surgery wasn't an easy process, he had to be conscious throughout the entire two-hour procedure.

“They did an electrical study first where they shocked my heart to create an episode,” he said.

“That happened pretty easily. They were able to locate the problem and burnt where they needed to. The rest of the procedure was spent shocking me again to check if it worked. That was the worst part of the operation.”

Hopper celebrates his first win on debut against Gold Coast in round 8, 2016. (Credit: Cameron Spencer/ Getty images).

The 20-year-old was a standout performer in his first season at the Giants, averaging 17 disposals in his 10 games.

Hopper has played all of his junior football with the condition, but wasn't diagnosed until late last year. He remembers his first episodes from when he was a child.

“It was a scare,” Hopper said.

“I remember as a young kid having an episode when I was very young. It was one of my first memories. I didn’t think much of it and didn’t tell my parents until years later.

“It never struck me as an issue. Last year I had an episode at the club which brought a diagnosis.”

Despite the surgery, Hopper is adamant it will have no impact on his season in 2017.

“I’m very confident I can just run out and play footy,” he said.

“I was back after just a week which was strange because I’ve had other operations like my knee where it has taken a lot longer to get back running again.”