Hypoplastic left heart syndrome (HLHS) is a spectrum of heart diseases in which the left-heart structures are underdeveloped. These structures include the mitral valve, the left ventricle, the aortic valve, and the aorta. HLHS is a congenital heart defect that begins during pregnancy. The cause of HLHS is unclear, and there are no known risk factors for this disease. It is not preventable.
It’s sometimes difficult to remember every detail of a fetal cardiology consult, so we’ve prepared everything you need to know in “An Expectant Parent’s Guide to Hypoplastic Left Heart Syndrome and Other Single Ventricle Defects” — written by our Fetal Cardiology coordinator, Terra Lafranchi, NP-C, and available in English and Spanish.
In most cases, children with hypoplastic left heart syndrome appear healthy at birth.
When a baby is not diagnosed during pregnancy, symptoms may develop within the first few hours or days of life:
HLHS is the result of under-development of sections of the fetal heart during the first eight weeks of pregnancy.
The cause of HLHS is complex and involves many factors. In some families, there is a genetic predisposition or tendency towards developing HLHS, but most families have no prior history of congenital heart disease. HLHS comes in many different forms. Some patients have a primary problem with their left ventricular heart muscle, some with the aortic valve, and some with the mitral valve. Many have problems with all three. These details matter to us at Boston Children’s, and we customize the care to meet your baby’s needs.
After a pre-natal ultrasound, Jack was diagnosed with HLHS. Now 17, Jack is an example of the innovation of the fetal cardiology team at Boston Children’s.
Most pregnant women have fetal ultrasounds during the course of their pregnancies. If a basic (level one or two) ultrasound shows the possibility of heart abnormalities, a more detailed cardiac ultrasound — fetal echocardiogram — can correctly diagnose your baby’s heart defect.
Most babies with HLHS appear healthy right after birth. If your baby was not diagnosed during pregnancy, it will become apparent within the first few hours to days that your baby has a heart defect. Some combination (not necessarily all) of the following medical tests are used to diagnose or evaluate HLHS:
Based on the results of these tests, your child’s doctors will determine the best approach to treatment.
A small number of babies with hypoplastic left heart syndrome may benefit from intervention before birth. Our highly trained cardiologists can use a needle or tiny balloon catheter to open abnormal heart valves or other obstructions. Learn more about the Fetal Cardiology Program.
If fetal intervention is not an option for your baby, treatments after birth will focus on stabilizing your baby and may include:
Shortly after birth, your child’s care team will take images of your baby’s heart using an echocardiogram to see every detail of your baby’s heart — the way the blood flows, the size and function of the ventricles, and how well the valves work.
Your child will usually need a series of three operations. The goal of these surgeries is to enable the fully-functioning right ventricle to do the work normally done by two ventricles and to separate the oxygen-rich blood from the oxygen-poor blood.
In some cases, a baby’s single ventricle heart can be converted into two functioning ventricles (biventricular circulation) through our Complex Biventricular Repair Program. This may be an option for children with borderline HLHS. In some situations, this repair can be the initial procedure, but in others, a series of procedures may be used to recruit the small left ventricle before converting the heart to biventricular circulation.
During the period between stage 1 and stage 2 surgeries, your baby’s heart circulation requires extra monitoring to prevent complications. Our Home Monitoring Program will give you goals for your baby’s growth and oxygen saturation levels and provide monitoring equipment for your baby. You’ll also get information on when to call.
The long-term outlook for children with HLHS continues to improve. Your child’s ultimate lifespan and quality of life depends on many factors. Every year, medical advancements further extend and improve the quality of life for those born with HLHS.
Your care team will have an ongoing relationship with your family and can help you create a long-term care program for your baby. The team can also advise you and your child on daily life issues such as exercise, activity levels, and nutrition.
At Boston Children’s Hospital, we have a team of specialists ready to evaluate your baby starting in the Fetal Care and Surgery Center. This team includes cardiologists who specialize in fetal assessments, and a team of nurses and other specialists who will make sure your baby is in the best possible condition when born. They will help you plan for every step along the way. In some cases, we are able to offer a fetal cardiac intervention even before the baby is born.
Boston Children’s heart surgeons treat a high volume of some of the most complex pediatric heart conditions in the world, with survival rates of more than 98 percent. Our approach to treating HLHS is different for every child, based upon their individual needs. We are one of the few hospitals in the country to offer complex biventricular repair, an approach pioneered at Boston Children’s.
The Boston Children’s Benderson Family Heart Center offers a unique combination of technical expertise, a state-of-the-art cardiac intensive care unit, and a continuous drive towards innovation that allows us to help when others cannot. We are here to serve as a resource to you. Some of our innovations include:
