Big Help for Little Hearts
It’s easy to understand why Dr. Lisa Hornberger is passionate about her job.
Imaging examining a living fetal heart the size of a lentil. Thanks to ultrasound technology, specialists like Dr. Hornberger, director of fetal and neonatal cardiology and section head of pediatric echocardiography at the Stollery Children’s Hospital, can do just that. She and her colleagues can see four chambers and the great arteries of a fetal heart at eight to nine weeks. At this point in gestation the fetus is about the size of a small kidney bean. Seeing into this early stage of development is more than simply fascinating; it has also given fetal cardiologists a window into how the heart evolves through development. Examining normal heart function and circulation at this early age will ultimately help to identify problems with the fetal heart function and structure and circulation.
With the ability to diagnose congenital heart defects prior to 10 weeks, Dr. Hornberger can prepare a family for a child born with a possible life-threatening condition. “Sometimes we are not clear how it will evolve so we are very conscious of how we counsel patients about what we see and what we understand. This is forging new territory,” she says.
With early diagnosis, families can plan for accommodations and support following the birth, and avoid the trauma of expecting a healthy baby, only to have him or her whisked away for critical care. Early diagnosis sis also helpful to the medical team, who can make plans in case the baby needs to be delivered early or should be born close to a cardiac centre. The proper support at birth can increase the baby’s chances for survival and better development and overall long-term healthy. Finally, earlier screening can help a family with the trauma of having a baby that was previously affected by or at the very high risk for fetal heart disease feel reassured that their fetus is healthy.
When an unborn baby’s heart rate is 200 to 300 beats per minute instead of the normal 150, Dr. Hornberger and her colleagues can treat the baby in utero by administering medication to the mother – which passes through the placenta, slowing the baby’s heart rate, preventing heart failure and helping the baby stay in utero until it is as close as possible to full term. A similar approach is used to help babies with a slow heart rhythm and heart failure or a slow rhythm called heart block had only a 50 per cent change of survival, but now with treatment through the mother, close surveillance and well-planned deliveries, they have a 90 to 98 per cent chance of survival," says Dr. Hornberger. Her team is participating in two large multi-centre research initiatives aimed at improving care and outcomes for babies with a heart rhythm that is too fast or too slow – the Canadian Institutes of Health Research-funded “FAST Trial” and Network Grant, both aimed at improving the diagnosis and outcome of fetal AV block due to maternal blood born factors.
Most families referred to Dr. Hornberger are considered high risk. Factors that can cause a pregnancy to have a high risk of heart defects include a mom with health issues such as a congenital heart defect or diabetes or when other babies in the family have been born with heart issues. Dr. Hornberger and her staff see roughly 1,200 to 1,300 such pregnancies every year, including 150 to 200 involving a fetus with a heart defect. A common critical heart condition for newborns in hypoplastic left heart syndrome, where the left ventricle of the heart is severely underdeveloped. Without interventions, HLHS is fatal, and without a diagnosis before birth or early after birth, affected babies can present to the Stollery when they are already very sick and having insufficient blood flow to critical organs.
Ninety per cent of these babies are not diagnosed before birth and plans can be made to stabilize the baby at birth. This results in treatments to ensure that they have sufficient blood flow to their body, helping them be much healthier going into surgery. A diagnosis before birth has been shown to improve short- and longer-term outcomes including healthier brain development, giving these babies a better chance at having a more normal life.
Dr. Hornberger’s research is also exploring what is different about heart function in premature babies. “As we are pushing to keep babies alive earlier, even as early as 22 to 24 weeks, we want to know how that affects the heart long term, whether we can optimize their care in the newborn intensive care unit and improve their long-term heart ad blood vessel health,” she says. Preliminary work with preterm babies has shown a clear difference in heart function in the preterm versus the full-term (nine-month) newborn, which may contribute to long-term health issues reported in adults who were delivered prematurely.
Dr. Hornberger loves following a family from diagnosis up to and after birth. “I enjoy the excitement that families have with a pregnancy,” she says. “I also know how difficult it is when there is a problem, so knowing ahead of time can help us prepare them. I feel a connection with the family and the kids after monthly, or, at times, weekly visits with the family before the baby is born. It’s an amazing experience and job. It’s so much fun.”
One such family had a baby with severe outflow tract obstruction on the left side of his heart. When the mother presented at 28 weeks, the baby had evidence of heart failure because his left ventricle was having difficulty with the obstruction. The team was worried the baby would die before birth. A medication was given to the mother to improve the heart function of the fetus, and within weeks the heart failure resolved. The baby was delivered by caesarean section at the Stollery Children’s Hospital and immediately underwent a balloon dilation of the aortic valve – following which his heart function improved. Although the baby required surgery at two weeks of age, he went into it in stable and good health. He is now a thriving, active child and his family has been very grateful to the team.
Twenty years ago, Dr. Hornberger fell in love with fetal cardiology and her passion and dedication to understanding the fetal and newborn heart will continue to offer increasing knowledge and support to families dealing with the heart issues of those dearest to them – their babies.
Dr. Hornberger’s research into fetal and neonatal cardiology has been supported by the Women and Children’s Health Research Institute (WCHRI) through generous funding provided by the Stollery Children’s Hospital Foundation and the Royal Alexandra Hospital Foundation.
Published Summer of 2015, Stollery Children’s Hospital Foundation