Prior to 1958 mortality rates for babies born with heart conditions was extremely high. But a groundbreaking open heart surgery performed 62 years ago at Greenlane Hospital by Sir Brian Barratt-Boyes changed medical history forever. Sonia Yee looks at the lead-up to the big day and the innovative machine used in the operation.

Helen Harris (nee Arnold) was about 10 or 11-years-old when she underwent New Zealand's first open heart surgery performed by Sir Brian Barratt-Boyes at Greenlane Hospital in September 1958.

"I was a blue baby," says Christchurch-based Harris who was born with a large hole between her right and left ventricles.

Listen: "I was a blue baby"- New Zealand's First Open Heart Surgery

Her surgical procedure was a progressive, groundbreaking event using new surgical techniques that drew attention from the international medical fraternity. An important innovation used in that procedure was a piece of equipment called 'The Melrose Machine'.

"They'd been working for two years to get the heart-lung machine up and running - they'd done 17 sheep before me," Harris says.

One out of 100 babies are born with some form of heart defect, and prior to Harris' operation, there was no effective treatment.

"Congenital heart disease is much more common than people realise," says Dr Alan Kerr - a cardiologist who spent much of his career working alongside Sir Brian.

"Many of those die in early infancy... some survive to be disabled and die prematurely, and some actually recover spontaneously," Dr Kerr says.

But the first open heart surgery required a lot of preparation and was an incredibly risky procedure. There were a number of factors that had to be taken into consideration.

From a medical perspective, Harris' age at the time made her an ideal candidate - she was the eldest among six other children of varying ages being considered for the operation.

Kerr says the risk of performing the surgery using the heart-lung bypass machine on babies could cause blood poisoning.

"Most of the first operations were done on older children because it was technically easier to do the surgery on someone who was bigger, rather than a baby," Dr Kerr says.

A bigger team was also brought on board, including engineers and technicians, to get the machine up and running, and to ensure that the operation was a success.

And clearly it was.

Today Harris is in her 70s and has undergone five procedures to-date, including four pacemakers, which help keep her heart beating…

Go to this episode on rnz.co.nz for more details