Pulmonary Atresia – Symptoms and Causes

Overview

Pulmonary atresia is a congenital heart defect present at birth where the pulmonary valve fails to form properly. Instead of a normal valve that opens and closes, a solid sheet of tissue forms, blocking blood flow from the heart to the lungs.

This creates a critical problem for oxygen delivery to the body.

Blood must find alternative routes to reach the lungs through other natural passages within the heart and arteries. While these alternative pathways are essential for fetal circulation, they typically close shortly after birth.

The severity varies between patients, but all cases need prompt medical management. Without treatment, oxygen levels remain dangerously low, causing serious health complications.

Signs and Symptoms

Pulmonary atresia typically shows signs very soon after birth. Babies with this condition may have:

• Blue or gray coloring of the skin, lips, or fingernails (cyanosis) from low oxygen levels
• Rapid breathing or difficulty breathing
• Unusual tiredness or fatigue
• Poor feeding habits
• Heart murmur (often heard during newborn screening)
• Cold, pale, or clammy skin

These symptoms happen because blood cannot flow normally from the heart to the lungs.

When Medical Help Is Needed

If you notice any of these symptoms in your newborn after leaving the hospital, seek emergency medical care immediately. Most cases of pulmonary atresia are detected shortly after birth while still in the hospital.

However, some signs might become more noticeable in the days following discharge. Quick medical attention is essential for proper treatment of this serious heart condition.

Causes

Doctors don’t fully understand why pulmonary atresia happens, but it develops during early pregnancy when the heart and major blood vessels are forming.

The critical period is within the first six weeks, when the baby’s heart begins to beat and develop its structure.

Pulmonary atresia occurs when the pulmonary valve fails to form properly. This valve normally allows blood to flow from the right ventricle to the lungs.

When the valve is completely closed or absent, blood cannot follow its usual path to pick up oxygen in the lungs.

There are two main types of pulmonary atresia:

• Pulmonary Atresia with Intact Ventricular Septum: In this type, the wall between the heart’s lower chambers (ventricular septum) has no holes.

• Pulmonary Atresia with Ventricular Septal Defect: This type features one or more holes in the ventricular septum, allowing blood to flow between the lower heart chambers.

The heart consists of four chambers working together to circulate blood throughout the body:

• Heart Structure:
  • Upper chambers: Two atria
  • Lower chambers: Two ventricles
• Normal Blood Flow Path:
  1. The right side receives blood and sends it to the lungs.
  2. Lungs add oxygen to the blood.
  3. Blood returns to the left side of the heart.
  4. The left side pumps oxygen-rich blood through the aorta to the body.

In pulmonary atresia, the pulmonary valve fails to form properly and cannot open. This blocks blood from flowing from the right ventricle to the lungs.

Before birth, this condition doesn’t immediately affect the baby because oxygen comes from the placenta, not the lungs. The oxygen-rich blood enters the right upper heart chamber and passes through an opening called the foramen ovale.

This natural hole between the top chambers allows blood to move to the left side and out to the body through the aorta. The challenge begins after birth when the baby needs functioning lungs for oxygen.

Normally, the ductus arteriosus closes shortly after birth, but in babies with pulmonary atresia, medications can be used to keep it open temporarily to allow oxygen exchange until surgery can be performed.

Risk Factors

Several factors may increase the chance of a baby developing pulmonary atresia during pregnancy:

• Obesity
• Alcohol or Tobacco Use
• Diabetes
• Certain Medications during pregnancy (including some acne and blood pressure medicines)

Family history plays an important role in heart defects. If you or a family member was born with pulmonary atresia or another heart problem, genetic screening might be helpful.

This screening can provide information about the risk of heart defects in future children.

Heart defects form while the baby is developing in the womb. The mother’s health conditions and lifestyle choices during pregnancy can affect how the baby’s heart forms.

Health Risks

Pulmonary atresia can be fatal if left untreated. Even after surgery, patients need lifelong medical follow-ups to monitor for potential problems.

Several complications may develop, including:

• Heart infections that affect the inner lining and valves (infectious endocarditis).
• Irregular heartbeats (arrhythmias) that disrupt normal heart function.
• Decreased heart strength which may limit physical activity.

Prevention

While completely preventing pulmonary atresia may not be possible, certain steps can reduce the risk of congenital heart defects.

Good prenatal care plays a key role in supporting heart health for developing babies.

Managing health conditions is essential. Women with diabetes should maintain controlled blood sugar levels.

Those taking medications for other conditions should consult healthcare providers about safe options during pregnancy.

Avoiding tobacco is crucial for heart development. Pregnant women should quit smoking and stay away from secondhand smoke, as exposure increases the risk of heart defects.

Maintaining a healthy weight before and during pregnancy helps protect against congenital heart problems. Obesity raises the likelihood of these conditions in newborns.

Getting vaccinated provides important protection. Rubella (German measles) can disrupt normal heart development when contracted during pregnancy.

Women planning pregnancy should:

• Have blood testing to check for rubella immunity
• Receive vaccination if not immune
• Complete vaccination before becoming pregnant