'It was like a light switch': Cork mum says 'superstar' Harper is coming on leaps following heart surgery

When she was born in August, 2024, Harper Hackett was a calm, content baby who loved her sleep.

But when she wasn’t meeting her milestones by six months old, her mum Tracey became concerned.

“She wasn’t really good at feeding and we’d never heard her giggle,” explains the Castlemartyr mother-of-two.

Tracey and her partner Dave have an older daughter, Robyn, who is now five.

“They always say don’t compare your children,” says Tracey, “but we were like, ‘okay, there should be some babble going on here’.”

Tracey voiced her concerns at Harper’s six-month check-up, and the doctor suggested that the child should undergo genetic testing to investigate the possibility of any underlying issues.

“It took about two weeks and then we got a phone call from the hospital. They said, ‘Look, can you come in?’ And at that stage I knew there was something.”

Tracey and Dave were informed that their baby girl had Mosaic Down Syndrome.

A rarer form of Down Syndrome, Mosaicism is only diagnosed by a blood test, and means that the carrier has a mixture of two types of cells - one type with the typical number of chromosomes, and the other with the extra chromosome characteristic of Down Syndrome.

In Harper’s case, 13% of her cells have an extra chromosome. She was born with none of the traditional markers of Down Syndrome and was thus not diagnosed at birth - common for children with Mosaicism.

“So, from that day on,” recounts Tracey, “Harper got called in for loads of different types of tests. She had her ears tested, came back perfect. Her eyes tested, came back no problems.”

It was good news across the board - Harper’s speech and language therapist was pleased with her receptive language, and she thrived at physical therapy.

Harper appeared to be developing just fine. After her initial worrying diagnosis, this all came as a relief to the family.

Then Harper was called in for her heart screening.

As with any type of Down Syndrome, heart issues can be a common feature of Mosaicism. But, as Tracey recalls, “we were like, ‘she’s passed every test. If there was something wrong with her, surely we’d see it at this stage’.

“So, I actually went to that appointment on my own because we just thought, ‘standard appointment at this stage’”.

It was this point, however, that doctors revealed to Tracey that they had found a defect in Harper’s heart and that she would need to go to Crumlin Children’s Hospital for further tests.

Harper was eight months old and appeared healthy. The news came as a huge shock.

“I felt so bad,” recalls Tracey. “I was here thinking, she is a perfect, healthy baby. And all along there was something there.

“But you just wouldn’t have ever thought it. She was just fabulous and always in great humour.”

Harper was diagnosed with a complex heart condition - holes in her heart and one valve instead of two on the left side.

In June, 2025 - when she was just ten months old - Harper underwent open-heart surgery at Crumlin, where doctors performed an AVSD (atrioventricular septal defect) repair, and left AV (atrioventricular) valve cleft closure.

The lead-up to the operation was a hugely stressful time for Tracey and Dave.

“We were petrified. We were still learning about the Mosaicism and all of a sudden trying to learn about heart defects,” says Tracey.

Their eldest daughter, Robyn, was just four at the time, so trying to explain to her that Mummy, Daddy and the baby would be away for a while was very difficult.

“It all just got a bit much, but we had great support,” says Tracey.

“The hospitals were great, and my family and Dave’s family were all brilliant.”

The operation itself took seven hours - a hugely tense wait for the parents, but the surgical team rang them every hour with an update.

The operation was a success and Harper made a speedy recovery.

“She was a superstar,” says Tracey. “She bounced back so well.

“It was like a light switch, all of a sudden she had so much energy and she just needed to get up and go.

“She actually started crawling in the ward! It was like, her heart is better and here she is. Like she got the missing part she needed”.”

Harper bounced back from the surgery so quickly that she was allowed to go home to Castlemartyr after just ten days in hospital.

Eight months on from the surgery, she’s starting to walk and is using sign language to express herself.

Now one-and-a-half years old, her personality is really starting to shine.

“She’s just very bubbly and smiley,” says Tracey. “She is absolutely obsessed with her big sister. If Robyn is doing it, she has to do it, too. She’s very brave that way.”

Harper will have a yearly check-up at Crumlin for the rest of her life, and also intermittent appointments at CUH. After the successful operation, her prognosis is good.

Harper is one of 500-600 babies born in Ireland each year with congenital heart disease (CHD), according to national charity Heart Children.

Tracey and her family discovered Heart Children after Harper’s diagnosis, and found their services hugely beneficial.

“We were looking for advice and we came across their page,” she said. “They were just so good at explaining stuff, and it’s all specific to children.

“They cover such a broad spectrum of different types of heart diseases, and they do so many community events that bring everyone together where you can talk to other parents.”

What advice would Tracey give to any parents whose child has recently received a heart condition diagnosis?

“You’re not alone. The help is there and what they can do nowadays is amazing.

“There’s always something, there’s always help, and there’s more that can be done for you.

“Heart Children were amazing - they helped me understand it all better. And the hospitals were amazing. The support we have received has been absolutely outstanding.”

Heart Children’s ‘The Beat Goes On’ conference, for people with congenital heart disease and their families, takes place in Dublin on Saturday, February 21, as part of Global Congenital Heart Disease Awareness Month. To register, visit www.heartchildren.ie