COMMENTARY

Diagnosing Heart Defects Early

The Role of Prenatal Diagnosis

Jack Rychik, MD

Disclosures

November 14, 2011

Editorial Collaboration

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My name is Jack Rychik. I am the director of the Fetal Heart Program at the Children's Hospital of Philadelphia. I am going to talk to you about prenatal diagnosis and its importance in the current era as we detect and manage congenital heart disease. The field of ultrasound has developed tremendously over the past 2 decades and we are now able to, with great access, identify very, very small structures within a developing human fetus.

There are a number of different ways in which ultrasound is performed during pregnancy. One can perform an early scan in the first trimester to essentially identify the gender or perhaps number of gestations that exist and look at growth. There is a general obstetric ultrasound that then takes place at approximately 18-20 weeks of gestation, which looks at different structures of the developing fetus: head, chest, abdomen, as well as some elemental aspects of the heart. There is also a more detailed type of study, a fetal echocardiogram. That is an ultrasound test in which one looks at the very fine details of the heart, looking at aspects of both anatomy and function, and it has truly revolutionized how we identify different forms of congenital heart disease. In fact, today it is much more common to identify heart disease before birth than it is after birth. Of course, with that there come a number of benefits.

What are the indications for performing a fetal echocardiogram? They can be divided into 2 different types. There are maternal indications, and then there are fetal indications. Maternal indications include a maternal or a family history of congenital heart disease, and that is somewhat of a risk factor for perhaps having a fetus with heart disease. There are maternal diseases and conditions such as diabetes mellitus and other genetic abnormalities that might place a pregnancy at risk for perhaps having congenital heart disease. There are some examples of fetal indications as well. There are a growing number of ways in which one can assess the first trimester fetus for a possible risk for a chromosomal abnormality, a genetic abnormality, or congenital heart disease. One in particular relates to a measurement of the nuchal thickness, which is a measurement of the amount of clear space behind the neck of a first trimester fetus between about 11-13 weeks of gestation. An increased nuchal translucency has been correlated in multiple studies with the potential presence of congenital heart disease. This is an indicator for performing the higher level fetal ultrasound scan or fetal echocardiogram.

The most common reason for referral for a fetal echocardiogram in the current era is nothing more than an obstetric scan that is performed with a sense of a possible abnormality, a screen that results in some question that then leads to referral for an echocardiogram.

What can we see in a fetal echocardiogram? Using specialized equipment, specialized training, and specialized ultrasound operators, we can assess the detailed anatomy of the different structures of the heart. We can look at the outflow tracks. We can look at the walls between the lower chambers of the heart. We can look at the vessels coming off the heart and look at what is referred to as the arches, the ductal arch and the aortic arch, and look at their position in space and location within the chest of the fetus.

Very importantly in the current era, we can also perform Doppler echocardiography where one can also assess flow characteristics through structures of the heart. There are very well-identified patterns of normal flow, and assessing the particular flow in a fetus provides an opportunity to determine whether there might be a difference in that flow pattern that then would result in detection of a particular condition.

Besides all of these very fancy and elegant ways we can look at the details of anatomy and heart function, what do we do with that information? In addition to the element of accuracy of diagnosis in the current era, we can take this information, process it, and counsel families accordingly as to how best to proceed. Using this information, we can optimize the management of the pregnancy, make decisions about where to deliver, make plans and develop strategies for how best to manage the transition to the postnatal life, and also support these families as they go through this process of a diagnosis of congenital heart disease. Research does show that, in fact, this can be a very, very stressful period for mothers who are carrying a fetus with a birth defect. Through programs such as the Fetal Heart Program here at the Children's Hospital of Philadelphia and others around the country, where a multidisciplinary approach is taken to managing the fetus and mother with congenital heart disease, we can incorporate our imaging information into a multidisciplinary comprehensive counseling strategy to optimize outcomes for these fetuses and result in an optimal outcome for the family as well.

Thank you very much.

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