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Congenital Heart Defect (CHD) affects the structure of the heart, the way it functions and the normal blood flow. There are around 18 different types of CHD recognized with several variations. CHD awareness week is observed every year from February 7-14 when awareness and education are provided for people. This is considered one of the most common types of birth defects and the leading cause of infant death in their first year of life.
Although the exact cause of heart defects aren’t known, it is presumed to be genetic and is associated with a combination of multiple genetic and environmental factors. There are different types of congenital heart defects which range from mild to severe. Some of these could be detected prenatally with a fetal echocardiogram, during newborn screening or discovered as they become older with clinical examination when the individual becomes symptomatic. With the advancement in treatments, infants with congenital heart defects are now living healthier and longer lives with many living into adulthood. The cardiologist will discuss the treatment options and the outlook for the particular heart defect. According to Centers for Disease Control and Prevention, around 1 in 100 births every year in the United States are diagnosed with a congenital heart defect and around 1 million children and 1.4 million adults in the United States are living with this defect in 2010.
Types of Congenital Heart Defects
Atrial Septal Defect: During pregnancy, there are several openings in the wall dividing the upper chambers of the heart which normally close on their own within several weeks or months. Sometimes, the hole may be larger than normal and may not close after birth and if the defect is large, the extra blood pumped into the lung arteries make the heart and lungs work much harder which over time can damage the lung arteries. Based on the severity of the condition, open-heart surgery or cardiac catheterization may be required.
Coarctation of the Aorta: This is the narrowing of the major artery (the aorta) which affects the blood flow and can cause high blood pressure or heart damage. Generally, no symptoms are identified at birth but can develop as early as the first week of the infant’s life. This condition can be treated with surgery or catheterization.
Ebstein’s Anomaly: This is the malformed heart valve not closing properly meaning the blood could leak from the lower to the upper chambers on the right side of the heart. Usually, most of the affected children don’t require surgery as it is mild, but when it’s severe, it could result in heart failure or cyanosis. In most cases, the surgery involves repairing of the tricuspid valve which cannot be made normal but the treatment can reduce the leaking.
Atrioventricular Septal Defect: Atrioventricular septal defect (AVSD) is the heart defect presenting holes between the right and the left sides of the heart’s chambers and the valves of the chambers may not be properly formed. As the result, the blood may flow where it shouldn’t and with less than normal amount of oxygen which could lead to congestive heart failure. There are two types of AVSD; complete AVSD and partial or incomplete AVSD. In a complete AVSD, there is a large hole in the middle of the heart allowing the blood to flow between all four chambers of the heart. A complete AVSD can occur when the valve fails to separate into the tricuspid and mitral value during pregnancy. The partial or incomplete AVSD occurs because of some defects such as a hole in the atrial wall or in the ventricular wall in the center of the heart.
Pulmonary Valve Stenosis: The pulmonary valve ensures the blood flows out of the heart and into the lungs. The pulmonary valve stenosis is defined by the fused heart valve that does not open completely. As the result, the blood pressure is much higher in the right ventricle while the heart is required to work harder to pump blood into the lung arteries. And, with time, this can result in damage to the heart muscle. This is considered one of the common types of heart defect in children although some of the children also have other heart defects. The treatment is based on improving the obstruction and leak although the valve cannot be made normal.
Identifying CHD in the Fetus
Identifying the heart defect in the fetus presents important implications such as pregnancy management and diagnosis of abnormalities in other organs. One of the tests used to detect fetal heart abnormalities is the fetal echocardiography that allows for a faster medical intervention as soon as the infant is born which in turn improves the chances of survival. Also, there is a wide range of fetal heart rates, the normal ranges from 120 to 160 but could also be as low as 90 without concern. However, important fetal heart problems include tachycardia (fast heart rate) and bradycardia (too slow heart rate). In certain cases with tachycardia, the fetus may require medication which is administered to the mother and in extreme cases can affect the wellbeing of the infant. However, the pediatric cardiologist will work together with the obstetrician to determine the risk and benefits of medication and the risk of abnormal heart rhythm against the risk of premature delivery.
What are the Risks for CHD?
One of the initial steps to prevention is tracking congenital heart defects and therefore reducing their effect. CDC’s researchers have reported that certain exposures during pregnancy could increase the risk for CHDs which includes;
- Women who were obese before pregnancy have shown an increased risk of CDCs
- Women who were diabetic before pregnancy have shown to be more at risk of having an infant with CDCs and other defects
- Women who have smoked during the month before pregnancy through the end of the first trimester are more likely to have an infant affected with CHDs
- Exposure to environmental factors such as infection or a drug could also cause heart defects
References
https://www.cdc.gov/mmwr/volumes/66/wr/mm6604a7.htm
https://www.cdc.gov/ncbddd/heartdefects/research.html#causes