Congenital Heart Disease

Congenital heart disease refers to a problem with the structure of the heart that is present from birth, occurring because the heart did not form entirely as expected during early pregnancy. These structural issues may involve an opening between chambers of the heart that should not be there, a heart valve that does not open or close properly, or blood vessels that are connected in an unusual way or missing altogether.

The impact of congenital heart disease ranges widely: some defects are minor and cause no symptoms, sometimes going undetected until later in life, while others significantly affect how blood flows through the heart and body and require treatment beginning in infancy. Congenital heart disease is one of the most common types of birth defect, and outcomes for affected children have improved substantially as diagnostic tools and surgical techniques have advanced.

Congenital heart defects are broadly divided into two categories based on their effect on oxygen levels in the blood.

• Acyanotic defects, such as a hole in the wall between heart chambers or a narrowed heart valve, generally allow the blood to carry a normal amount of oxygen, though they can still place strain on the heart over time.
• Cyanotic defects, sometimes called critical congenital heart disease, more significantly disrupt normal blood flow so that oxygen-poor blood circulates through the body, which can cause a bluish tint to the skin, lips, or nail beds.

Within these broad categories, defects vary considerably in complexity, from a single, relatively simple structural issue to combinations of several abnormalities affecting multiple parts of the heart at once.

The symptoms of congenital heart disease depend heavily on the specific defect and its severity. Some newborns show clear signs shortly after birth, including a bluish tint to the skin or lips, rapid or labored breathing, and difficulty feeding due to tiring quickly during sucking. Poor weight gain despite adequate feeding attempts, unusual fatigue or sweating during feeding, and a rapid heart rate can also indicate an underlying heart problem. In milder cases, symptoms may not appear until later in infancy or childhood, and may include shortness of breath during activity, poor growth compared with peers, or swelling in the legs, abdomen, or around the eyes. Some congenital heart defects produce no noticeable symptoms at all and are identified only through a routine examination that detects an abnormal heart sound.

In most cases, the specific cause of a congenital heart defect cannot be identified, and the condition is understood to result from a combination of genetic and environmental influences that affect heart development in the earliest weeks of pregnancy. Genetic factors play a role in some cases, including certain chromosomal conditions that are known to be associated with a higher likelihood of heart defects. Environmental influences during early pregnancy, such as certain maternal infections or exposure to specific medications, have also been linked to an increased risk, though a clear cause is not identified in the majority of cases.

Certain factors are associated with a higher likelihood of congenital heart disease and can inform prenatal counseling and monitoring. A maternal infection with rubella during early pregnancy is a well-established risk factor, which is part of why rubella immunity is checked before or early in pregnancy. Insufficiently controlled maternal diabetes, particularly when blood sugar is elevated during the early weeks of pregnancy when the heart is forming, meaningfully raises the risk. Certain medications taken during pregnancy, along with alcohol use and smoking, have also been associated with a higher likelihood of heart defects, making these modifiable factors worth discussing with a prenatal care provider. A family history of congenital heart disease, particularly in a parent or sibling, is another recognized factor that may prompt closer prenatal evaluation of the baby's heart.

Because the specific cause is often unknown, congenital heart disease cannot always be prevented, but certain steps can help reduce risk where modifiable factors are present. Confirming rubella immunity before pregnancy and avoiding exposure to the infection during pregnancy is an effective preventive measure. Careful management of maternal diabetes before conception and throughout early pregnancy helps lower the risk associated with elevated blood sugar during the critical period of heart development. Avoiding alcohol, tobacco, and any medications not approved by a prenatal care provider during pregnancy further reduces modifiable risk. For families with a known history of congenital heart disease, genetic counseling before or during pregnancy can help clarify individual risk and guide prenatal monitoring.