What is Congenital Heart Disease?
Congenital Heart Disease involves an abnormality of the heart, whether it is a structural defect, a problem with the fetal heartbeat, or a functional problem with the heart squeeze or filling.
The developing heart starts as a tube, which then folds and fuses in a complex way, resulting in a muscular pump with four chambers and four valves. It is not surprising that small errors in development can lead to a wide variety of structural abnormalities in the 4 chambers, the 4 heart valves, the veins and arteries.
Most forms of congenital heart disease can be detected by ultrasound from the third month of pregnancy on (14 to 15 weeks). As the pregnancy progresses, diagnosis becomes more accurate: it becomes easier to tell if there is progression of a minor problem to a major one, and it becomes easier to see subtle details and most minor heart problems. Usually minor problems will not need any special care at birth but may need attention later in life; most major heart problems seen in the fetus will need surgery or other intervention in infancy. Abnormal development of either one of the pumping chambers (right or left ventricle) can lead to devastating problems after birth, which often require multiple complex open heart surgeries and, even when successful, result in long-term limitations for the child and a shortened lifespan (so-called ‘single ventricle physiology’).
How is it Diagnosed?
The diagnosis of congenital heart disease is established by ultrasound. Close follow-up may be necessary to rule out worsening of the process, and the fetus is checked regularly to ensure normal growth. Additional testing, including genetic testing and other types of ultrasound or magnetic resonance imaging, or MRI, may be recommended.
Most congenital heart diseases (with the exception of arrhythmias) are best treated after the baby is born. We can intervene in other ways, though: with advance knowledge of a heart problem that will require specialty care or surgery, it is possible to change the plans for delivery of the baby. One can change the mode, place and time of delivery.
Mode of delivery: For almost all heart conditions, vaginal delivery does not put the baby at an increased risk of complications. For that reason, most physicians now recommend normal delivery, unless there are obstetrical reasons to proceed with a C-section.
Place of delivery: As long as the fetus is inside the womb, the heart and other organs are well protected. After birth, however, the transition from receiving oxygen from the placenta to receiving oxygen by breathing may be difficult for a baby with heart disease if crucial fetal blood vessels in the chest start to close as they normally would in a baby after birth. With advance knowledge of the heart condition, special medications can be used to keep these vital structures open after birth, stabilizing most babies with heart problems. The baby can be safely transported to a treatment center, as long as certain precautions are taken. However, if the diagnosis has been made beforehand, it may be advisable to have the baby be born directly in such a treatment center (i.e., a center with a neonatal intensive care unit and immediate access to a pediatric cardiothoracic surgery service).
Time of delivery: There are no known advantages to early delivery in most babies with congenital heart disease, and there are many drawbacks to being born early or small including higher rates of complications related to the cardiac surgery. Most centers have therefore recommended term or near-term delivery (between 38 and 40 weeks).
Fetal intervention: Transplacental Therapy
Fetal therapy may be offered in two situations: Heart rhythm abnormality in which medications may reasonably be expected to improve the rhythm or restore it to normal; and blocked cardiac valves or channels (preventing normal blood flow) that might respond to invasive techniques to unblock them while the baby is still in the womb.
Transplacental medical therapy. The heartbeat of a normal, healthy fetus ranges between 120-160 beats per minute and has a regular rhythm. When the rhythm is irregular, or the heartbeat is too fast or too slow this is considered a “dysrhythmia” or “arrhythmia.” While most irregular rhythms do not get a baby into trouble before birth, fast or slow rhythm disturbances can cause the baby to develop heart failure and even die before birth. One of the most common abnormal rhythms is “supraventricular tachycardia” in which the fetal heartbeat is very fast. Though less common, slow heartbeats can also be treated. The treatment primarily involves giving one medication (or more) to the mother so that it can cross into the bloodstream of the fetus. Because careful monitoring of both mother and fetus are necessary to ensure the safety of this treatment, cardiologists familiar with the use of the medications in pregnancy should always be involved in the care of these patients.
Invasive Cardiac Intervention
It is understood that some severe obstructive lesions such as hypoplastic left heart syndrome can evolve from a simple valve blockage during the development of the fetus. This observation has prompted experimental attempts at inserting a needle into the mother’s pregnant uterus and directly through the chest and heart of the fetus, in order to open up the blocked valve. This is done with a balloon-tipped catheter instrument, inserted through the long needle (not unlike "balloon angioplasty" in adults with blocked heart vessels). This intervention is so far limited to a few hospitals with highly skilled teams. In some fetuses, the procedure will halt the evolution from aortic stenosis (blocked aortic valve) to hypoplastic left heart syndrome (and in others, from pulmonary atresia to hypoplastic right ventricle).
Fetal intervention for restrictive atrial septum, in which the normal opening between the two upper heart chambers starts to close too soon (or closes in a fetus with small left heart structures) has been proposed. Using a similar technique as described above, an an opening between the two upper chambers can be created or enlarged. Preliminary experience has shown the procedure to be feasible, and some babies are more stable after birth than would have been expected otherwise. Still, longer-term outcomes from this procedure are unknown.
Although the potential for prevention of severe congenital heart disease through such invasive strategies is exciting, there are important considerations that limit routine application. There is significant risk of premature delivery or even death of the fetus during the procedure. Even if the fetal intervention is successful, most children still require additional (sometimes extensive) cardiac operations or procedures after birth and in childhood. Fetal therapy procedures should be performed only by physicians with experience in ultrasound-guided operations in pregnancy. The final decision about choice of therapy will be influenced by the assessment of the potential for response of the defect to the therapy and technical issues, such as the gestational age of the pregnancy, along with the parents’ preferences.
What to Expect After Birth
Most common heart defects, such as holes between the chambers (atrial septal defect, or ASD, and ventricular septal defect, or VSD) and even more complex conditions such as transposition of the great arteries and tetralogy of Fallot, can be successfully managed after birth. The infant with congenital heart disease is attended to by neonatologists and pediatric cardiologists, who will ensure that the infant remains stable and receives adequate oxygen and nutrition, that the diagnosis is accurate, and that the cardiothoracic surgeons have all of the information they need prior to surgery. An intravenous line may be inserted, so that fluids and medication can be given. Once the baby is stable and breathing well, cardiac surgery or interventional catheterization can be performed if immediately necessary. Often, however, a definitive repair cannot be done. In those cases, a variety of palliative strategies to temporize the cardiac condition may be done in stages, or stabilization with referral for cardiac transplantation if necessary can be pursued. In some severe cases, if surgery is not expected to substantially improve the quality of life for the infant, some parents may choose to allow the child to pass away naturally rather than continue aggressive therapies.
Most Fetal Treatment Centers have useful information online. A list of NAFTNet centers, links and their respective website can be found by clicking here.
Other useful sites, including national organizations, patient- and parent support groups, professional societies and governmental agencies, can be found on our resources page.
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Below are a few sites that have specific information on congenital heart disease: