Monday, February 11, 2013

February 11, 2013 - Congenital Heart Defect Causes and Risks

There is no known official prevention for CHD because the causes seem to be some combination of genetic and/or environmental factors that cannot be specifically identified.   The information below is pretty general, so it seems that early detection is the best way for babies with CHD to have a fighting chance.


As quoted from the March of Dimes:

What causes congenital heart defects?
In most cases, scientists do not know what makes a baby's heart develop abnormally. Genetic and environmental factors appear to play roles.

Scientists are making progress in understanding the genetics of heart defects. Since the 1990s, they have identified about 10 gene mutations (changes) that can cause isolated (not accompanied by other birth defects) heart defects (3). For example, a March of Dimes grantee identified a gene that can cause a heart defect called an atrial septal defect (a hole between the upper chambers of the heart), and one that may contribute to hypoplastic left heart syndrome (underdevelopment of the heart’s main pumping chamber) (4, 5).

Environmental factors can contribute to congenital heart defects. Women who contract rubella (German measles) during the first three months of pregnancy have a high risk of having a baby with a heart defect. Other viral infections, such as the flu, also may contribute, as may exposure to certain industrial chemicals (solvents) (2). Some studies suggest that drinking alcohol or using cocaine in pregnancy may increase the risk of heart defects (2).

Certain medications increase the risk. These include (2):
  • The acne medication isotretinoin (Accutane and other brand names)
  • Thalidomide (approved only for a rare, severe skin disorder, but sometimes used for other conditions)
  • Certain anti-seizure medications
Some studies suggest that first-trimester use of trimethoprim-sulfonamide (a combination of antibiotics sometimes used to treat urinary-tract infections) may increase the risk of heart defects (2).

Certain chronic illnesses in the mother, such as diabetes, may contribute to heart defects (2). However, women with diabetes can reduce their risk by making sure their blood sugar levels are well controlled before becoming pregnant.

Heart defects can be part of a wider pattern of birth defects. For example, at least 30 percent of children with chromosomal abnormalities, such as Down syndrome (intellectual disabilities and physical birth defects) and Turner syndrome (short stature and lack of sexual development), have heart defects (3). Children with Down syndrome, Turner syndrome and certain other chromosomal abnormalities should be routinely evaluated for heart defects.

Heart defects also are common in children with a variety of inherited disorders, including Noonan syndrome (short stature, learning disabilities), velocardiofacial syndrome (craniofacial defects and immune deficiencies), Holt-Oram syndrome (limb defects) and Alagille syndrome (liver, skeletal and eye defects) (3). 

Additionally, parents who have had one child with CHD do have a chance of other children being born with the same or similar defects.  Depending on the specific defect, the statistics vary but all parents of children with CHD are encouraged to have serious discussions with pediatric cardiologists and/or genetic counselors before getting pregnant again.


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