What Are Congenital Heart Defects?

Congenital heart defects (CHDs) are structural abnormalities in the heart that are present at birth. These defects can involve the walls of the heart, the valves within the heart, or the arteries and veins that carry blood to and from the heart. 

These defects can disrupt the normal flow of blood through the heart, affecting how blood is pumped to the rest of the body. CHDs can range from simple issues, like holes in the heart, to more complex malformations, such as problems with the heart’s walls, valves, or blood vessels. 

Some CHDs may cause significant health problems or require medical intervention soon after birth, while others may not be discovered until later.

Are Congenital Heart Defects Common?

Congenital heart defects are the most common type of birth defect, affecting approximately 1% of all live births worldwide. This prevalence means that roughly 40,000 babies are born with CHD each year in the United States alone. 

The incidence of CHDs can vary by geographical region, socioeconomic status, and maternal health factors. For instance, certain genetic conditions, maternal diabetes, obesity, or infections during pregnancy can increase the risk of a baby being born with a heart defect.

When examining specific types of congenital heart defects, the prevalence can vary widely. Some of the more common CHDs include:

• Ventricular Septal Defect (VSD): This defect involves a hole in the wall separating the heart’s lower chambers (ventricles). It is the most common type of CHD, occurring in about 3 out of every 1,000 live births.
• Atrial Septal Defect (ASD): A hole in the wall between the heart’s upper chambers (atria). This defect is less common than VSD but still significant.
• Tetralogy of Fallot (TOF): A complex CHD involving four different heart defects, including a VSD, pulmonary stenosis, right ventricular hypertrophy, and an overriding aorta. It occurs in about 5 out of every 10,000 live births.
• Transposition of the Great Arteries (TGA): A condition where the two main arteries leaving the heart are reversed. This severe defect occurs in about 3 out of every 10,000 live births.
• Coarctation of the Aorta (CoA): A narrowing of the aorta, the main artery that supplies oxygenated blood to the body. This defect is found in about 4 out of every 10,000 live births.

These statistics underscore the importance of early detection and treatment to improve outcomes for affected individuals.

Source: Difference Between

Overview of the Heart’s Structure and Function

To understand congenital heart defects, it’s essential to have a basic knowledge of the heart’s structure and function. The heart is a muscular organ about the size of a fist, located slightly left of the center of the chest. It functions as a pump to circulate blood throughout the body. 

The heart has four chambers: two upper chambers called atria and two lower chambers called ventricles.

• Atria: The right atrium receives deoxygenated blood from the body and pumps it into the right ventricle. The left atrium receives oxygenated blood from the lungs and pumps it into the left ventricle. The atria functions primarily as reservoirs for blood.
• Ventricles: The right ventricle pumps deoxygenated blood to the lungs for oxygenation. The left ventricle pumps oxygenated blood to the rest of the body. The ventricles are responsible for pumping the blood.

The heart also contains four valves that ensure blood flows in the correct direction:

• Tricuspid Valve: Located between the right atrium and right ventricle.
• Pulmonary Valve: Between the right ventricle and pulmonary artery.
• Mitral Valve: Between the left atrium and left ventricle.
• Aortic Valve: Between the left ventricle and aorta.

Blood flow through the heart follows a precise route:

1. Deoxygenated blood enters the right atrium from the body via the superior and inferior vena cava.
2. It moves through the tricuspid valve into the right ventricle.
3. From the right ventricle, blood is pumped through the pulmonary valve into the pulmonary artery and to the lungs for oxygenation.
4. Oxygenated blood returns from the lungs to the left atrium via the pulmonary veins.
5. It then passes through the mitral valve into the left ventricle.
6. Finally, the left ventricle pumps the oxygenated blood through the aortic valve into the aorta, distributing it throughout the body.

The synchronized contraction and relaxation of the heart’s chambers ensure efficient blood circulation, delivering oxygen and nutrients to tissues and removing waste products. 

Some Important Terminologies About CHDs You Should Know 

• Septal Defects: Abnormal openings in the septum (wall) between the heart chambers, which can cause a mixing of oxygen-rich and oxygen-poor blood.
  • Atrial Septal Defect (ASD): An opening in the atrial septum, allowing blood to flow between the atria (upper heart chambers).
  • Ventricular Septal Defect (VSD): A hole in the ventricular septum, allowing blood to pass from the left ventricle (oxygen-rich) to the right ventricle (oxygen-poor).
  • Atrioventricular Septal Defect (AVSD): A complex defect involving abnormalities in the atrial and/or ventricular septum and the valves between the upper and lower heart chambers.
• Valvular Defects:
  • Stenosis: Narrowing of a heart valve, restricting blood flow.
    • Aortic Valve Stenosis: Narrowing of the valve between the left ventricle and the aorta.
    • Pulmonary Valve Stenosis: Narrowing of the valve between the right ventricle and the pulmonary artery.
    • Tricuspid Valve Stenosis: Narrowing of the valve between the right atrium and the right ventricle.
    • Mitral Valve Stenosis: Narrowing of the valve between the left atrium and the left ventricle.
  • Regurgitation (or Insufficiency): Leakage of blood backwards through a valve, due to incomplete closure.
    • Aortic Valve Regurgitation: Backflow of blood from the aorta back into the left ventricle.
    • Pulmonary Valve Regurgitation: Backflow of blood from the pulmonary artery back into the right ventricle.
    • Tricuspid Valve Regurgitation: Backflow of blood from the right ventricle back into the right atrium.
    • Mitral Valve Regurgitation: Backflow of blood from the left ventricle back into the left atrium.
  • Atresia: Complete closure or absence of a heart valve.
    • Pulmonary Atresia: Absence of a pulmonary valve, requiring alternative pathways for blood flow.
    • Tricuspid Atresia: Absence or severe narrowing of the tricuspid valve, affecting blood flow between the right atrium and right ventricle.
• Defects of the Heart Wall:
  • Hypoplastic Left Heart Syndrome (HLHS): Underdevelopment of the left side of the heart, leading to impaired blood flow.
  • Double Outlet Right Ventricle (DORV): Both major arteries (aorta and pulmonary artery) arise from the right ventricle instead of their normal locations.
  • Ebstein’s Anomaly: Abnormal development of the tricuspid valve, causing it to be positioned lower than normal and not function properly.
• Defects of the Great Vessels:
  • Transposition of the Great Arteries (TGA): A condition where the aorta and pulmonary artery are switched, leading to separate circulation of oxygen-poor and oxygen-rich blood.
  • Coarctation of the Aorta: Narrowing of the aorta, which restricts blood flow to the lower part of the body.
  • Interrupted Aortic Arch: Absence of a portion of the aorta, leading to separate circulation to the upper and lower parts of the body.
• Diagnostic and Treatment Terms:
  • Fetal Echocardiography: Ultrasound examination of the fetal heart to assess structure and function during pregnancy.
  • Cardiac Catheterization: This invasive procedure uses a thin tube (catheter) inserted into blood vessels to diagnose and treat heart conditions.
  • Balloon Valvuloplasty: Procedure using a catheter with a balloon to widen a narrowed heart valve.
  • Fontan Procedure: Surgical procedure to redirect venous blood flow directly to the pulmonary arteries in patients with certain complex CHDs.
  • Ventricular Assist Device (VAD): A mechanical pump implanted to assist a failing heart by pumping blood from the ventricles to the rest of the body.
  • Heart Transplantation: Surgical procedure to replace a diseased heart with a healthy donor heart.

Conclusively, congenital heart defects are a range of structural issues with the heart that develop before birth, affecting its ability to function properly. While some CHDs are mild and require little or no treatment, others can be life-threatening and demand immediate intervention.