Learn about the Fetal Echocardiogram and how it helps to study the fetal heart.

Summary

  • A Fetal Echocardiogram is usually performed between 16 - 22 weeks of gestation
  • It studies the structure and function of the fetus’s heart to detect the presence of a Congenital Heart Defect.
  • Pregnancies may be at risk for congenital heart disease for a variety of fetal, maternal or familial reasons.
  • The main observations that would be made during the course of the scan procedure are the structure of the heart, blood flow and beating rhythm.
  • Even in the case of a totally normal, high quality study, not all heart problems can be ruled out. This is because the circulation in the fetus changes after birth.

In the modern era with the current advances in imaging technology, care begins in the womb. Fetal medicine specialistsare trained to make a diagnosis of heart disease early during the pregnancy, counsel families on the nature and prognosis of detected abnormalities, and establish appropriate management plans for affected pregnancies prior to delivery.

The aim is to educate families in order to optimize the outcomes of children born with congenital heart disease.

What is a Fetal Echocardiogram?

A Fetal Echocardiogram is a prenatal ultrasound test that studies the structure and function of the fetus’s heart to detect the presence of a Congenital Heart Defect. It uses the same ultrasound technology as other prenatal scanning examinations performed by Fetal Medicine Specialists. The Fetal echo is usually performed between 16 - 22 weeks of gestation, but this test can also be performed either earlier (13 weeks) or as late as the end of the third trimester in pregnancy but is technically difficult during the advanced stage of pregnancy.

What Is Congenital Heart Disease (CHD)?

A congenital heart defect is a problem in the structure of the heart that is present at birth. Signs and symptoms depend on the specific type of problem. The defect can vary from minor to life-threatening. Approximately one out of every 100 live born infants (~1 percent) will be born with a congenital heart defect, which usually develops during the embryologic formation of the heart (first trimester).

These defects can be straightforward, such as a hole in the heart connecting two chambers (atrial or ventricular septal defect) or an abnormal heart valve (pulmonary or aortic stenosis).

They can also be more complex defects in which a major portion of the heart does not form (such as hypoplastic left heart syndrome) or the anatomic connections are abnormal (such as transposition of the great arteries).

Some infants will be born with a heart defect that requires immediate stabilization of the baby shortly after birth, followed by surgery.

What Causes Congenital Heart Disease (CHD)?

Both genetic and environmental factors are suspected in the formation of congenital heart disease. Specific gene defects (22q11 deletion, trisomy 21) have been identified as having a very strong association between congenital heart disease and more generalized syndromes. In addition, there are other factors such as maternal diabetes, and specific medications (such as anticonvulsants) that have been associated with increased rates of heart defects.

What are the medical practices employed?

The ultrasound study includes two-dimensional imaging, 3-dimensional imaging, colour flow , and Doppler evaluation of blood flow. After the study is performed, the patient is counselled by the Fetal Medicine Specialiston the diagnosis and prognosis.

How is the test performed?

The test is either performed from above (abdominal) or through the vagina (transvaginal). As in the routine pregnancy tests, a sound wave is transmitted that is reflected by the baby’s heart and is captured to project an image of the heart on the screen. This helps the Fetal Medicine Specialistto better see the structure and function of the unborn child's heart.

What is observed during the procedure?

The main observations that would be made during the course of the scan procedure would be the structure of the heart, blood flow and beating rhythm.

Some factors such as maternal lupus require several studies to be conducted even if the first one is normal. There also may be a structure that is not seen as well as the doctor would like due to the position of the baby and the patient may be asked to return even though the suspicion of a problem is low. Even in the case of a totally normal, high quality study, not all heart problems can be ruled out. This is because the circulation in the fetus changes after birth. Additionally, very small holes between the lower chambers of the heart are hard to see.

Fetal echocardiograms can reliably be performed any time after 17–18 weeks gestation; however if scanning is done before 18 weeks, the patient will likely be asked to return for more definitive pictures to confirm the findings on the early study.

The diagnosis of a heart defect has significant implications for the overall health of the fetus; certain heart defects may significantly increase the risk of genetic problems such as Down’s Syndrome. The finding of benign tumors in the heart makes the diagnosis of Tuberous Sclerosis, a genetic syndrome that has significant implications for abnormal brain development much more likely.

Who Should Have a Fetal Echocardiogram?

Pregnancies may be at risk for congenital heart disease for a variety of fetal, maternal or familial reasons.

Fetal risk factors include:

  • An abnormal appearing heart
  • Abnormal heart rate or arrhythmia on routine screening ultrasound
  • Aneuploidy (chromosomal abnormality)
  • Increased nuchal translucency thickness at first trimester evaluation
  • Non-cardiac fetal structural abnormalities
  • A two-vessel umbilical cord
  • Twins
  • Fluid accumulation in the fetus
  • If the unborn baby has been diagnosed with a genetic abnormality including disorders with abnormal number of chromosome; Down syndrome, for example
  • If a heart abnormality is suspected on routine ultrasound
  • If there are abnormalities outside of the heart of the fetus noted on routine prenatal ultrasound; examples include extra fluid around the lungs or the heart or an abnormality of another organ such as the kidneys or brain.
  • Abnormal fetal heart rate or rhythm. This can be an irregular heartbeat or heart rate that is too fast or too slow.

Maternal risk factors include:

  • Maternal diabetes, lupus or other systemic disease that involves the heart (such as DiGeorge Syndrome)
  • First-trimester use of known teratogens
  • IVF pregnancies
  • Maternal congenital heart disease
  • If the mother has taken medications that are known to cause congenital heart defects.
  • If the mother has specific health problems such as diabetes (the type that the mother had prior to pregnancy)
  • If the mother had specific infections during pregnancy such as rubella or CMV

Familial risk factors include:

  • If a first degree relative has been diagnosed with a congenital heart defect. First degree relative includes the mother or father of the baby as well as any siblings of the baby
  • If there is a known family history of disorders that are passed along from generation to generation such as Marfan's syndrome or tuberous sclerosis

Is the test definitive?

While fetal medicine specialistswork to detect defects to the maximum extent possible, it must be realized by the patient and her family that imaging procedures cannot detail extremely minor portions of the heart. Heart defects often develop over time such as those that affect the heart muscles or valves.

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