A baby girl is "thriving" after a life-saving operation by surgeons who used a 3D-printed model of her heart to prepare.

Thirteen-month-old Penny has a congenital heart condition which affects about five in every 10,000 babies, called Tetralogy of Fallot.

She underwent open-heart surgery at Birmingham Children's Hospital, where her parents faced an agonising wait for news until their daughter came round.

"All of a sudden she had a twinkle in her eye," said her father, Brad.

"The anaesthetic was getting out of her system and she was back. She was Penny again."

The BBC has followed Penny's journey, as her family and doctors prepared for the procedure with the aid of the printed replica of her heart, which helped build a picture of exactly what needed to be done.

Earlier this year, Penny's parents Brad and Lizzie found it understandably tough to imagine just what their baby daughter was about to face.

On the outside she looked healthy, but without surgery she could become gravely ill.

Speaking back then at home in Broome, in Worcestershire, Brad said of the impending operation: "That's the day, and I'd say this out loud, for me when the world will stop and it will only restart again when she's back through and I can see her face."

To help them understand the process, 3D-printed replicas of her tiny heart were made at Aston University.

"Having the replica means that we can see exactly what a heart condition looks like," Dr Tristan Ramcharan, a consultant paediatric cardiologist, explained.

"Before we go into theatre, we can have a look and see where a hole is, we can see where the narrowing is and, in select and more complicated cases, we can use that to understand exactly where our patches have to go and where we have to cut.

"It then makes the actual operation easier, more straightforward and potentially less complicated."

The model helped Penny's parents understand more about the procedure too. But weeks before the operation, during a visit to see the 3D heart for the first time, they were understandably worried.

"I can't wait to be on the other side," said Lizzie.

"It's just a day that's looming over us. But we know it's got to happen. It's something that Penny needs, so, yeah, we are a bit anxious."

Using CT scans, biomedical engineers worked closely with doctors to ensure the four defects in Penny's heart were accurately represented.

The partnership between Aston University and nearby Birmingham Children's Hospital uses technology to help both parents and doctors better understand complex heart conditions. The team has now produced 3D-printed models of a number of infants' hearts.

The project is run by the cardiology team at Birmingham Children's Hospital, in conjunction with Aston University, and is funded by the hospital's charity.

Antonio Fratini, from the university's Engineering for Health Research Centre, said: "Surgeons sometimes tell us which side of the heart they want to see and which areas are of particular interest. We don't print the whole heart every time.

"Sometimes they also ask us to make cuts in the model so they can open it up and see inside."

Weeks later, an anxious Brad and Lizzie waited at Birmingham Children's Hospital for their daughter to be taken to the operating theatre. It was early in the morning and only just getting light.

Holding his daughter in his arms, Brad said he was "apprehensive and nervous".

"Because what she has is hidden, it's very difficult to understand that it is life threatening and it needs to happen. But I did have a moment last night thinking actually I could just run away and I felt like protecting her, but the logical part says no this has got to be done."

Soon afterwards the couple carried Penny to the operating suite alongside a nurse, and were allowed to be with her until she'd had general anaesthetic.

"I just crumbled," admitted Brad afterwards.

"I thought I was here to support Penny and Lizzie, and all of a sudden Lizzie was supporting me."

The couple then faced an agonising five-and-a-half hour wait for news.

When the news came, it was positive. The operation had been a success. But seeing Penny in intensive care was difficult at first. She initially had an "external pacemaker", explained Brad.

"She needed support when she came out," he said, but was "reassured" by staff.

Penny's parents were finally able to hold her six days later. "I took great pleasure in that," said Brad.

In the coming weeks she will have further checks using a heart monitor and eventually, be checked annually for the rest of her life.

But generally, the outlook for Penny is now bright.

"We're delighted that Penny is recovering so well following her surgery. Penny and her family have shown incredible bravery throughout, and it's wonderful to see them able to look forward to the future," Ramcharan said.

Follow BBC Birmingham on BBC Sounds, Facebook, X and Instagram.