Pulmonary atresia is a congenital heart defect where the pulmonary valve, which controls blood flow from the heart to the lungs, does not form correctly. This condition is present at birth and prevents blood from reaching the lungs to pick up oxygen.
What is Pulmonary Atresia?
Pulmonary atresia occurs when the pulmonary valve, located between the right ventricle and the pulmonary artery, is completely blocked or absent. This obstruction prevents deoxygenated blood from flowing from the heart to the lungs. As a result, blood cannot receive oxygen, impacting the body’s overall oxygen supply.
To circulate in the body, blood must find alternative routes to reach the lungs or bypass them. Before birth, the ductus arteriosus, a natural connection between the aorta and pulmonary artery, allows some blood to bypass the lungs. After birth, this connection typically closes, but in pulmonary atresia, it becomes a temporary lifeline for blood flow to the lungs.
There are two primary types of pulmonary atresia, differentiated by the presence or absence of a ventricular septal defect (VSD). Pulmonary atresia with intact ventricular septum (PA-IVS) means there is no hole in the wall separating the heart’s lower chambers. In PA-IVS, the right ventricle often remains underdeveloped due to limited blood flow during fetal development.
Conversely, pulmonary atresia with ventricular septal defect (PA-VSD) includes a hole in the ventricular septum. This VSD allows some blood to flow into and out of the right ventricle, which can lead to better development of the right ventricle and pulmonary artery.
Recognizing the Indicators
Symptoms of pulmonary atresia often become apparent shortly after birth, typically within the first few hours or days. A primary indicator is cyanosis, a bluish tint to the skin, lips, and nail beds, resulting from insufficient oxygen in the blood.
Affected infants may also exhibit rapid breathing or difficulty breathing, indicating their body’s struggle to compensate for low oxygen levels. Poor feeding and extreme lethargy or unusual sleepiness are common additional signs.
Diagnosing the Condition
Diagnosis of pulmonary atresia can sometimes occur before birth through a fetal echocardiogram, a specialized ultrasound of the baby’s heart. This detailed imaging allows medical professionals to visualize the heart’s structure and blood flow. If concerns arise during a routine prenatal ultrasound, a fetal echocardiogram may be ordered to confirm the diagnosis.
After birth, diagnosis typically involves a physical examination, where a doctor listens for heart murmurs, an abnormal sound caused by turbulent blood flow. Pulse oximetry, a non-invasive test measuring oxygen levels in the blood via a sensor on the baby’s foot or hand, can also indicate low oxygen saturation. Other initial tests may include a chest X-ray to assess heart and lung size, and an electrocardiogram (ECG) to record the heart’s electrical activity.
The definitive diagnosis of pulmonary atresia is typically made with a postnatal echocardiogram. This ultrasound provides detailed images of the heart’s chambers, valves, and major blood vessels, allowing for precise identification of the pulmonary valve malformation and its impact on blood flow. In some cases, a cardiac catheterization, a more invasive procedure, may be performed to gather detailed information on blood flow and pressure within the heart, or as a preliminary step for certain interventions.
Treatment Approaches
Immediate postnatal care for pulmonary atresia often involves administering medication, specifically prostaglandins (like alprostadil), intravenously. This medication helps keep the ductus arteriosus open, maintaining a temporary pathway for blood to reach the lungs until more definitive treatment can be initiated.
Surgical approaches for pulmonary atresia vary depending on the specific anatomy of the heart, particularly the size of the right ventricle and pulmonary artery. For some infants, a Blalock-Taussig (BT) shunt may be placed as a temporary measure. This shunt creates a connection between a major artery branching off the aorta and the pulmonary artery, increasing blood flow to the lungs.
Many individuals with pulmonary atresia, especially those with an underdeveloped right ventricle, require a series of staged surgical procedures. The Glenn procedure involves connecting the superior vena cava directly to the pulmonary artery, allowing deoxygenated blood from the upper body to flow to the lungs without passing through the heart.
The Fontan procedure is usually the final stage of surgical repair. This operation reroutes deoxygenated blood from the lower body directly to the pulmonary arteries, completely bypassing the heart’s right side. This series of surgeries aims to improve oxygenation and reduce the workload on the single functioning ventricle.
Catheter-based interventions can also play a role in managing pulmonary atresia. These procedures involve threading a thin tube through a blood vessel to the heart. Techniques such as balloon valvuloplasty can be used if a pulmonary valve is present but closed, or stent placement may be performed to keep the ductus arteriosus open. These options improve blood flow.
Long-Term Outlook
With appropriate medical and surgical management, individuals born with pulmonary atresia can lead fulfilling lives. Lifelong follow-up care with a cardiologist specializing in congenital heart disease is important to monitor heart function and address any potential complications.
While many achieve good outcomes, some individuals may face ongoing challenges. These can include the need for additional procedures or surgeries later in life, heart rhythm abnormalities, or reduced exercise tolerance. Regular check-ups and adherence to medical advice are important for managing these possibilities.