Babies with life-threatening but treatable heart disease are more likely to survive if the disease is picked up before birth a new study shows – but researchers say too few pregnant women in Aotearoa New Zealand receive an antenatal diagnosis.

In New Zealand, four babies die each year due to late-diagnosed congenital heart disease. The condition – where the heart doesn’t form properly - is the leading cause of infant deaths related to birth defects. If the condition is picked up prior to birth, care after birth means babies remain well until treated with surgery – usually within the first week. Survival rates are excellent; in the nine years covered by this study, all babies who received the treatment survived.

But the study also showed, for the first time, how much of a difference early detection makes.

Researchers from the University of Auckland-based Liggins Institute and Starship Child Health analysed all recorded cases of two variants of the condition in babies born at term between 2006 and 2014 – a total of 253 babies. One percent (one) of babies diagnosed before birth died, compared to seven percent (11) of babies diagnosed following birth. Overall, fewer than half of babies were diagnosed before birth, though the figure rose from 32 percent in the first three years to 47 percent in the last three years.

Lead author Dr Elza Cloete from the Liggins Institute says the difference in survival rates was largely because early diagnosis can allow for arrangements for the mother to give birth at Auckland City Hospital, which is next door to the country’s only child heart surgery centre at Starship Children’s Hospital.

But if the diagnosis is made following birth, mother and baby have to be transferred urgently to Starship Hospital. This delay can cost the baby’s life.

Reasons for a missed antenatal diagnosis include the mother being unable to access an appropriate antenatal ultrasound scan at the right time, or the defect not being detected during the scan. This can be due to a variety of reasons including the length of time set aside for the scan, the technical difficulty of the scan, the skill of the sonographer, and high BMI in the pregnant woman making it more challenging to gain clear images.

“Our findings highlight the need to ensure all pregnant women can access high quality antenatal scans at the right times, regardless of where they live,” says Dr Cloete, a Liggins Institute PhD student and neonatologist.

“Encouragingly, there has been an improvement in antenatal detection, probably due to sonographer training, greater awareness of this condition and recent guidelines about which pictures should be obtained during the scan. But we must continue striving to improve antenatal detection rates through better access to scans of sufficient quality to detect these problems.”

Radiologist Dr Rachael McEwing was a member of the Ministry of Health’s Maternity Ultrasound Advisory Group, which made recommendations to the Ministry for improved
quality control and audit of maternity scans.

“This study highlights the importance of high quality scanning and audit,” she says.

She adds that one of the heart conditions covered in the study is generally only able to be diagnosed in the third trimester, and third trimester scans are not routine at present.

The other two researchers were Professor Frank Bloomfield, Liggins Institute Director and neonatologist at National Women’s Health at Auckland City Hospital, and Dr Tom Gentles, Director of the national paediatric cardiac service at Starship Child Health.

Baby Frank’s story

By the time he was nine days old, Wellington newborn Frank Bramwell-Stevens had undergone four heart surgeries. They saved his life. He was born with a rare congenital heart defect called “transposition of the great arteries”, where the aorta and pulmonary artery are switched around.

The condition was first picked up by the routine antenatal scan his mother, nursing student Emma, had at 20 weeks’ pregnancy. She remembers being upset by the offhand, abrupt manner of the sonographers – at a radiography chain – who told the couple of the possible diagnosis. But after that, the care the family received from their midwife, Wellington Hospital’s maternal fetal medicine unit, and the team at Starship Child Health was fantastic, Emma says.

Subsequent tests confirmed the diagnosis and Emma was closely monitored until she reached 37 weeks, when the family flew to Auckland and were put up in Ronald McDonald House. (The DHB paid for Emma and husband Danny Steven’s flights, and the couple paid for their two-year-old daughter, Marlene, to come too.)

“If was fairly disruptive with all the logistics of relocating, but we were lucky that Danny’s work was really understanding and he was able to work from Auckland, and I’d just finished my semester.”

Baby Frank was born August 20, just after his due date. “He came out shouting and he hasn’t stopped since!” Emma laughs. “He looked so much better than I was expecting. The majority of his body wasn’t getting oxygenated blood so I thought he would be blue, but he had good colour and was a good size.”

Three hours after birth he had his first surgery – a balloon atrial septostomy, in which doctors widened the hole between his atria (the two heart chambers that blood enters) to allow more oxygenated blood to flow into the body.

“The next day, he came off the ventilator and we were able to have cuddles and start breast-feeding.”

A week later he had the main surgery in which doctors switched the arteries. “It was pretty stressful,” Emma says. “We tried to distract ourselves, took the ferry to Devonport with our daughter and had some lunch. He’d gone in at 8.30am, and we were so relieved when we got the call from the surgeon at 2.30pm to say it went well.”

After a brief return to the operating theatre to fix a bleed, the family visited him.

“He had his chest open with all these tubes coming out of it, covered with clingfilm. They’d left it open in case of swelling. That was quite confronting. They operated on him again the next day to close it.”

Frank was discharged a week after the main surgery – “we flew through recovery” – and is now a healthy six-week-old. “He’s doing incredibly well and you’d never know from looking at him that he’d been through all that,” says Emma. “He’s just got this wonderful scar which will make for a great story!”

Emma says she was surprised to learn that fewer than half of the babies with congenital heart disease are diagnosed before birth. “Having that antenatal diagnosis meant we were able to be prepared and organised, and had time to process the news; rather than giving birth and then getting the diagnosis and having all that information coming at you – I can’t imagine what that would be like.

“People often ask us, ‘how did you cope?’. Having that antenatal diagnosis was a big part of it. You have time to ask questions, do your own research, and make all the arrangements. You learn that the treatment is bread-and-butter for Starship, and you have time to speak to organisations like Heart Kids, which have been an amazing support for us.

“In our experience, it all felt very organised and in-hand. It makes me really sad to think that some families don’t get that, and to think what the potential outcomes might have been for Frank had he not been diagnosed antenatally.”