Fetal cardiovascular abnormalities are fairly common, with congenital cardiac disease occurring in between two and six of every 1,000 live births. Many of these anomalies can be detected by ultrasound at between 18 and 22 weeks. Early detection can greatly improve outcomes and significantly reduce mortality when compared to infants who are diagnosed at birth. About half of all fetal cardiac abnormalities are either fatal or involve complex surgical correction. However, advancements in technology and procedures have expanded treatment options for many conditions that could not be resolved in the past.
What are Cardiovascular Conditions?
The fetal cardiovascular system begins forming shortly after the baby is conceived. The heart is the first organ to develop, and it begins pumping blood throughout the fetus’s body by the end of its fifth week. However, in some cases – and for many different reasons – the baby’s heart does not develop normally before birth. This can lead to a number of abnormalities which require medical intervention. They can include:
- Fetal arrhythmia (tachyarrhythmia, bradyarrhythmia)
- Atrial septal defects
- Ventricular septal defects
- Atrioventricular canal defect
- Ebstein anomaly
- Hypoplastic right ventricle
- Hypoplastic left ventricle
- Pulmonary stenosis and atresia
- Aortic stenosis
- Coarctation of the aorta
- Tetralogy of Fallot
- Double outlet right ventricle
- Truncus arteriosus
- Transposition of great arteries
- Heterotaxy syndrome
- Fetal cardiomyopathy
- Intracardiac tumors
What Causes Fetal Cardiovascular Conditions?
A congenital heart defect, or CHD, occurs when the heart doesn’t form properly in the womb. This can be a defect in the structure of the heart or the great vessels. The cause of a congenital heart defect is often unknown, but some types of CHDs could be the result of the following:
- An abnormal number of chromosomes
- Single gene defects
- Environmental factors
- A combination of genes and environmental factors
CHDs can also result if the mother takes certain types of medications during the first few weeks of pregnancy. This is a critical time for the baby’s heart to grow, and certain medications, such as antiseizure medications or lithium, could affect that growth. Prenatal alcohol exposure and maternal obesity are also significant risk factors for CHDs.
Maternal illnesses can also affect the baby’s heart. Some examples include:
- Phenylketonuria (PKU) if the mother doesn’t stay on the special PKU diet while pregnant
- Insulin-dependent diabetes
- Systemic lupus erythematosus
- Connective tissue disorder (Marfan syndrome)
Pregnancy from assisted reproductive technology can place a baby at higher risk for CHD.
Family history can also play a role in congenital heart conditions; if a first-degree relative has a CHD, children have about three times greater risk of being born with a heart defect as well.
Detecting Fetal Cardiovascular Conditions
Imaging technology and interventional treatments have greatly improved the diagnosis and treatment of fetal cardiovascular conditions. Most often, cardiac conditions in a fetus will be diagnosed by ultrasound, although other types of technology may be used as well. These noninvasive imaging techniques can include:
- Magnetic resonance imaging (MRI)
- Fetal electrocardiography (ECG or EKG)
- Magnetocardiography (MCG)
Treating Fetal Cardiovascular Conditions
A baby who is diagnosed with a cardiovascular condition either before or at birth can be at greater risk for certain medical conditions later in life. That’s why it’s critical to have the right team of specialists who have experience in pediatric cardiology, pediatric cardiac intensive care, and pediatric cardiovascular surgery working with you. Because of advancements in treatments and technology, many conditions today can be treated more effectively than ever before, including conditions that once were considered life threatening.
If a heart defect is detected, your fetal cardiology specialist will work with your primary care physician to determine an appropriate treatment plan. This may include ongoing fetal stress tests as well as more frequent appointments with your obstetrician and members of your fetal and pediatric cardiology team as your delivery date gets closer. You may also be prescribed medications during your pregnancy to help treat the condition.