The heart begins to take shape in the first several weeks of pregnancy when your baby is no bigger than a half inch. During these critical weeks, congenital heart defects can develop and affect how your baby’s heart functions after birth. A healthy heart is a complex organ with unique structures that work together to pump oxygen-rich blood to the body.

What Happens in the Heart

The heart has muscle, four chambers, four valves and muscle. Triggered by electrical signals, the heart muscle rhythmically contracts and relaxes to pump blood. Like every muscle in the body, the heart muscle needs oxygenated blood carried by the coronary arteries to function. The right coronary artery delivers blood to the right side, back and bottom of the heart muscle. The left coronary arteries supply blood to the left side of the heart both in the front and back.

Inside the heart, there is a right and left side and two chambers in each. The upper chamber on each side is called the atrium. The lower chamber are ventricles. Four valves act as one-way doors between the atria and ventricles and the aorta and pulmonary artery to control the flow of blood through the heart.

The right side of the heart receives oxygen-poor blood from the body. The blood enters the heart through the right atrium. The heart contracts, forcing blood into the right ventricle. A second contraction moves the blood into the pulmonary artery to the lungs for oxygen.

The left pulmonary vein returns oxygen-rich blood to the heart through the left atrium. Heart muscle contractions force oxygenated blood into the left ventricle, then up into the aorta to be delivered to tissue and organs throughout the body.

Once the blood has circulated through the body and exhausted its oxygen supply, veins carry the blood back to the heart.

How the Parts of the Heart Fit Together

The heart has many different parts and abnormality in the heart’s structure may affect how effectively the heart and lungs work. Serious heart conditions may threaten your child’s life or cause congestive heart failure. The parts of the heart include:

  • The superior vena cava is a large vein that brings oxygen-depleted blood to the right atrium from the upper body. The inferior vena cava serves the same function, carrying oxygen-poor blood from the lower body.
  • The right atrium receives blood from the venae cavae and passes it to the right ventricle through the tricuspid valve.
  • The right ventricle pumps blood through the pulmonary valve into the pulmonary artery that takes the blood to the lungs to be oxygenated.
  • The pulmonary veins bring oxygen-rich blood to the left atrium in the heart.
  • The left atrium pumps the oxygen-rich blood forward through the mitral valve to the left ventricle.
  • The left ventricle performs the final contraction to push blood through the aortic valve into the aorta to be delivered to the body.

When the Heart Doesn’t Work Properly

Congenital heart defects may be detected before birth during fetal echocardiography (ultrasound), soon after birth or within your baby’s first few months. Your child’s doctor may hear a heart murmur during a physical examination or notice signs of a serious heart problem, such as blue-tinged skin. A baby with a severe heart condition may have rapid breathing, swelling, trouble feeding and shortness of breath.

More moderate heart defects may not be diagnosed until later in your child’s life. If present, symptoms may include tiring and becoming short of breath easily when playing or exercising and swelling in the hands, ankles or feet.

If your child’s doctor suspects a problem in the heart, she may recommend seeing a pediatric cardiologist.