Louise pictured with her son, Ben, had major surgery. Credit: Apex

Louise Banks, aged 23 from Exeter, collapsed regularly when exercising but was told it was epilepsy.

When she was 16, trainers at her local gym realised she had a serious problem, but the condition was not diagnosed until January this year.

The one and a half inch (4cm) hole has now been repaired by surgeons.

Louise, who has a four-year-old son, first knew something was wrong at the age of eight when she collapsed at her primary school and was sent to hospital.

She was diagnosed as "a fainty child" and sent back to school.

Louise's case is quite unusual, especially as her heart has also coped with the added strain of pregnancy

Ellen Mason, British Heart Foundation

By the age of 14 she could feel her heart stopping and starting again with a jump up to 70 times a day.

When she joined a gym aged 16 the training instructors were stunned to see her heart rate drop when she used a running machine.

They urged her to see a doctor but, again, her condition was misdiagnosed.

She nearly died during the birth of her son, Ben, because her heart fluttered erratically.

Ultrasound

Only now, at the age of 23, has she discovered the problem was a massive hole in the heart.

It was spotted in January when she saw a new GP at her local practice.

He sent her for an ultrasound scan - the first she had had, which revealed the unusually large hole between two chambers of the heart.

It was allowing oxygenated blood to mix with deoxygenated blood, causing her to collapse.

Louise, who lives with her partner Matthew Folland, underwent a six-hour operation to close the hole at Southampton General Hospital.

She has been left with no lasting effects apart from a 10-inch (25cm) scar on her chest.

"I always knew there was something wrong, I could feel my heart start and stop. It was like a baby wriggling in my chest," she said.

"I don't feel angry with the doctors for missing it - I would rather have been operated now than 23 years ago when science wasn't so advanced."

Louise, who now wants to train as a paramedic, plans to organise a ball to raise funds for charity, at which she will be able to dance properly for the first time.

"I'm looking forward to my new life. It will be great to be able to dance without collapsing."

Ellen Mason, a cardiac nurse for the British Heart Foundation said large holes in the heart are normally diagnosed at a much younger age.

"Louise's case is quite unusual, especially as her heart has also coped with the added strain of pregnancy.

"Louise was fortunate to have a doctor who noticed her symptoms, because carrying on untreated with a hole in the heart of this size would have eventually put intolerable strain on her heart.

She added: "Medical technology has advanced since Louise was born, especially in the area of prenatal screening, so it seems likely that a hole in the heart of this size would be detected at an earlier stage nowadays."