KidsMD Health Topics

Congenital Heart Defects

  • A congenital heart defect (CHD) is a heart problem that’s present at birth. It’s caused by improper development of the heart during fetal development.

    • 1 percent of babies are born with a CHD.
    • Nine out of every 1,000 babies born in the US are born with a congenital heart abnormality.
    • One third of these babies require intervention to prevent death in the first year of life.
    • 85 to 90 percent of CHDs have no known causes.
    • 5 to 6 percent are related to chromosome abnormality.
    • 3 to 5 percent are related to single gene defects.
    • 2 percent are related to environmental factors.
    • Approximately 1.3 million people living in the US today were born with a congenital heart defect, and at least half of these individuals are under age 25.

    How Boston Children’s Hospital approaches congenital heart defects

    The first operation to correct a congenital heart defect was performed in 1938 by Boston Children’s surgeon, Robert Gross, MD. Today, we perform more than 1,200 cardiac surgeries each year.

  • What causes congenital heart defects?

    New mothers often wonder if they did anything to cause their baby’s CHD. It’s important to remember that in most cases, CHD has no known cause. Most of the time, there is no identifiable reason as to why the heart defect occurred. However, some at-risk groups include:

    • women who take anti-seizure medication while pregnant
    • women who take lithium while pregnant
    • women who have phenylketonuria but do not adhere to the special diet necessary
    • women who have insulin-dependent diabetes or lupus
    • women who contract rubella while pregnant
    • There is approximately an 8-10% risk that a mother with a congenital heart defect (CHD) will have a baby with some type of CHD, but not necessarily the same defect as the mother.  High risk prenatal monitoring of the mother and baby is recommended.

    If you fall into any of these categories, it’s important to talk to your doctor while pregnant.

    What are some types of CHD?

    Several CHDs are detected and treated early in infancy.

    What are some symptoms of CHD?

    Symptoms of CHD in infants and children include:

    • cyanosis (a bluish tint to the skin, fingernails and lips)
    • Respiratory Distress and poor feeding
    • poor weight gain
    • recurrent lung infections
    • inability to exercise or play vigorously

    Are CHDs genetic?

    About 1 percent of all children are born with CHD, but the risk increases if either parent, or a sibling, has CHD.

    • If you’ve have one child with CHD, your second child has a 1.5 to 5 percent chance of having a CHD.
    • If you have two children with CHD, your third child has a 5 to 10 percent chance of having CHD.
    • If the mother has a CHD, the child has a 2.5 to 18 percent chance of having CHD.
    • If the father has a CHD, the child has a 1.5 to 3 percent chance of having CHD.

    If you have a CHD, we recommend that you speak with a genetic counselor or genetic specialist at Boston Children’s before becoming pregnant. In families with a CHD either in the parents or offspring, a fetal echocardiography can be performed in the second trimester to determine the presence of major heart defects.

    Other causes of CHDs

    Chromosome abnormalities:

    • Chromosomes are the structures in your cells that contain your genes, which determine traits such as eye color and blood type. Usually there are 46 chromosomes in each cell of the body. Having too many or too few chromosomes results in health problems and birth defects.
    • Five to 8 percent of all babies with CHD have a chromosome abnormality.
    • There are a number of chromosome abnormalities associated with congenital heart defects, including:

    Single gene defects:

    • When a gene is mutated, a number of health problems may occur. Several health problems with one genetic cause are often referred to as a syndrome. Some of the genetic syndromes associated with a higher incidence of heart defects include:
      • Marfan syndrome
      • Smith-Lemli-Opitz syndrome
      • Ellis-van Creveld
      • Holt-Oram syndrome
      • Noonan syndrome
      • Mucopolysaccharidoses
  • Congenital heart defects are often first detected when your doctor hears an abnormal heart sound or heart murmur when listening to your baby’s heart.

    Depending on the type of murmur your doctor hears, he or she may order further testing such as:

     At Boston Children’s, if your doctor suspects your child has some type of genetic syndrome, we may ask a clinical geneticist to evaluate your child.

    If your child has been diagnosed with a chromosomal or other genetic abnormality, genetic counseling is helpful to determine the risk of heart defects occurring in any other children you may have in the future.

  • At Boston Children's Hospital, we specialize in treating a wide range of congenital heart conditions in babies before and after they are born. Babies with congenital heart problems are treated by specialists called pediatric cardiologists. These physicians diagnose heart defects and help manage the health of children before and after surgical repair of the heart problem. Specialists who surgically correct heart problems in the operating room are called pediatric cardiovascular surgeons or pediatric cardiothoracic surgeons.

    Treatment is based on the severity of your child's heart condition. Some mild heart defects don't require any treatment. Others can be treated with medications, interventional procedures or surgery. The most common defects we treat include:

    • Aortic stenosis: This is a narrowing of the aortic valve of the heart that obstructs blood flow throughout the body. The severe form of aortic stenosis can lead to a serious defect called Hypoplastic left heart syndrome.
    • Pulmonary atresia: This is a malformation of the pulmonary valve that obstructs the outflow of blood from the heart to the lungs. This can lead to underdevelopment of the right ventricle.
    • Hypoplastic left heart syndrome with a restrictive atrial communication: This is an underdevelopment of the left ventricle of the heart that results in inadequate blood flow throughout the body.

    Problem: Kids with congenital heart defects often suffer from heart failure, meaning their hearts can't pump adequately. And since heart muscle has very little growth capacity after birth—nowhere near enough to fix a severe cardiac injury—heart transplant is often the sole treatment option.

    Innovative solution: Researchers in Boston Children's Cardiovascular Program have discovered a growth factor, called neuregulin1 (NRG1), that can reawaken the heart's regenerative capacities, and may be able to strengthen the heart after a heart attack and in children and adults with heart failure. NRG1, which is involved in the initial development of the heart and nervous system, spurred heart-muscle growth and recovery of cardiac function when injected systemically in rats; preparations are underway to test the growth factor in humans. Doctors now envision a time when patients will receive monthly infusions to build up their hearts.

    Problem: Invasive open-heart surgery in infants can be risky
    Innovative solution: The Medtronic Melody Transcatheter Pulmonary Valve is a prosthetic valve that was developed to treat patients with congenital heart disease affecting the function of the pulmonary valve. The valve is implanted through a catheter procedure, rather than a more invasive open-heart surgical procedure. This makes the demands on your child's recovery much easier and far less intensive.

    The device has been approved for use in Europe and Canada for years.  Once approved by the Food and Drug Administration, pending review of a five-center investigative study that included Boston Children's, the valve will be the first catheter-implanted valve approved in the United States.

    Results of the study, published in October of 2009, include 29 patients who underwent successful surgery.

    • Of 24 patients who had Class II or III heart failure (mild to moderate limitation of physical activity) before the procedure, 19 had improved by at least one functional class at six months, and no patient's function had declined
    • No patient had more than mild pulmonary regurgitation

    Based on results from the study, Medtronic is currently working on an improved model.

    Longer term studies are needed to monitor the quality of the device. Like other prosthetic valves, the Melody Transcatheter Pulmonary Valve is likely to need replacement several times over the course of a patient's life due to wear and tear. However, since the Melody can be implanted through a catheter, there is minimal risk to the patient compared to valves that can only be implanted surgically.

    Hunting down the genetic causes of congenital heart disease

    While there is a lot of evidence that congenital heart disease can be caused by genetic mutations, many of the affected genes remain unknown. In the effort to discover more genetic causes, Boston Children's is joining with Brigham and Women's Hospital (BWH) as part of the Bench to Bassinet Program, a six-year, $100 million collaboration funded by the National Heart Lung and Blood Institute that aims to propel basic pediatric cardiac research toward clinical treatment.

    Jane Newburger, MD, MPH, associate cardiologist-in-chief at Boston Children's, and Christine Seidman, MD, director of the Cardiovascular Genetics Center at BWH, will lead the effort. Clinical geneticists and basic scientists will collect DNA samples from pediatric heart patients and map the genetic program that directs heart development. Patients will undergo cardiac imaging to establish their disease phenotype while their samples undergo DNA sequencing and genomic analysis.

    The data will be combined with data from the other Pediatric Cardiac Genomics Consortium (PCGC) institutions funded by the Bench to Bassinet Program, including Yale University, Mt. Sinai School of Medicine, Columbia University and Children's Hospital of Philadelphia. The partnership also allows the collaborators to share patient samples and technology.

    “Competition inspires people to work quickly, but this particular area of research begs for collaboration,” says co-investigator Amy Roberts, MD, director of Boston Children's Cardiovascular Genetics Research Program who, under separate grants, is studying the genetics of hypoplastic left heart syndrome and Noonan syndrome.

    Separately funded projects by William Pu, MD, of Boston Children's Cardiovascular Program, will use induced pluripotent stem cell technology to model congenital heart disease in the lab, and explore how alterations in microRNA expression and gene transcription factors may lead to heart disease.

  • How fetal testing can change the outcome for kids with heart defects

    When a heart condition is diagnosed prenatally, caregivers can proactively provide additional testing, delivery planning and counseling that benefitsTworetzky the baby’s health and parents’ piece of mind.

    In some cases, it’s even possible to perform fetal therapy on the child before he or she is even born. Boston Children’s Fetal Cardiology Program can try to repair heart valves the size of a pen point in a fetal heart no bigger than a grape; all while the child is still in the mother’s womb.

    Fetal or in-utero therapy is a very complex process that brings together cardiologists, obstetricians, anesthesiologists and nurses in a team effort to perform these procedures. In the following video, Wayne Tworetzky, MD, director of Boston Children Fetal Cardiology Program discusses how difficult these procedures can be, not just because of the small size of fetal hearts, but also because of complications that can arise from performing invasive surgery on a fetus when the mother carrying the baby is perfectly healthy.

    In-utero heart surgery is an amazing feat of modern medicine, but before doctors ever get to that point a problem needs to be recognized. Ultrasounds are essential in monitoring fetus development in the womb, but they’re not perfect.

    Ultrasound“Virtually all pregnant women who receive pre-natal care will have a fetal ultrasound during the course of their pregnancy, but that doesn’t mean the ultrasound catches everything,” says Tworetzky. “Congenital heart defects such as hypoplastic left heart syndrome or transposition of the great arteries, and others, can be detected by ultrasound, but research shows that about half the time, they’re overlooked.”

    Fetal ultrasounds don't always catch potential heart defects.

    “With planned and specially managed care before and after delivery of a child with a CHD, caregivers can treat the infant’s heart right from the start,” Tworetzky says. “They can also minimize the risks for future problems.

    Download these tips in PDF format for you to print and bring to your ultrasound

    During a fetal ultrasound, Tworetzky suggests parents ask the technician and the doctor the following questions concerning the fetal heart:

    • Do you see four chambers in the baby’s heart? (Desired answer is yes)
    • Are there two upper chambers (left and right atria) with valves controlling blood flow into the heart? (Desired answer is yes)
    • Are there two lower chambers (left and right ventricles) with valves controlling blood flow out to the body (aortic) and lungs (pulmonary)? (Desired answer is yes)
    • Do the two valves and vessels (aorta and pulmonary arteries) exit the heart in a crossing fashion? (Desired answer is yes)
    • Are there any large holes between the lower chambers of the heart? (Desired answer is no)
    • Is the baby’s heart normal? (Desired answer is yes)

    If the answers to the above are as desired, then almost all serious heart defects, and  > 90% of all heart defects, can be ruled out.

    If the ultrasound shows the possibility of a heart defect, parents should immediately make an appointment with a pediatric cardiologist, who will have access to the most advanced and accurate diagnostic tests. “If further testing show signs of a heart defect your caregivers will help you plan appropriately for your baby’s birth,” Tworetzky says. “This way you’ve given clinicians as much time as possible to make the birth, and early treatment, as smooth as possible.”

    One treatment option—and it sounds like something out of science fiction—is repairing CHDs on hearts no bigger than a grape while the baby is still in the mother’s womb.

    As you might imagine, it’s an incredibly complex and delicate procedure that brings together doctors, surgeons and nurses. These procedures can be difficult, not just because of the small size of fetal hearts, but also because of complications that can arise from performing invasive surgery on a fetus when the mother carrying the baby is perfectly healthy.

    And in this recent interview with NPR, Tworetzky talks about fetal cardiology and we hear from the parents of a Boston Children’s patient who had surgery while she was still in her mother’s womb.

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