Pulmonary Atresia: Symptoms, Types, Causes and Treatment

Pulmonary atresia is a rare but serious congenital heart defect that disrupts normal blood flow from the heart to the lungs. Affecting both newborns and children, pulmonary atresia presents a diverse range of symptoms, anatomical differences, and treatment challenges. Understanding its clinical presentation, classification, underlying causes, and modern management options is critical for families and healthcare providers alike. This comprehensive article delves into each of these areas, synthesizing the latest research and clinical guidelines.

Symptoms of Pulmonary Atresia

Pulmonary atresia can cause a variety of symptoms, which often appear soon after birth. The severity and specific manifestations depend on the type and complexity of the defect. Early recognition of these symptoms is crucial, as prompt intervention can be lifesaving.

Symptom	Description	Onset/Severity	Source(s)
Cyanosis	Bluish skin/lips due to low oxygen	Birth/Severe	2 7 9
Rapid breathing	Tachypnea, often with distress	Birth/Infancy	2 7
Fatigue	Tiredness, poor feeding in infants	Early infancy	2
Heart murmur	Abnormal heart sounds on examination	Detected at birth	2 4
Exercise intolerance	Difficulty with activity, older children	Childhood, post-surgery	2
Sudden death	Unexpected, sometimes unexplained	Infancy/Childhood	2

Table 1: Key Symptoms

Overview of Symptom Presentation

Pulmonary atresia is most often identified in the newborn period. The classic sign is cyanosis—a bluish tint to the skin and lips—caused by insufficient oxygen in the blood. This is because blood cannot flow normally from the right side of the heart to the lungs for oxygenation 2 7. In many cases, rapid breathing (tachypnea) and signs of respiratory distress are also present within hours or days after birth.

Symptom Spectrum and Severity

• Cyanosis: The most striking and universal feature, often severe and persistent.
• Feeding Difficulties and Fatigue: Newborns may tire quickly during feeds and fail to gain weight, reflecting inadequate oxygen delivery to tissues 2.
• Heart Murmurs: Abnormal heart sounds may be detected on routine newborn examination, prompting further cardiac evaluation 2 4.
• Exercise Intolerance: As children grow, those who survive with inadequate repair may struggle with physical activity, experiencing fatigue or shortness of breath 2.
• Sudden Death: Unfortunately, sudden and sometimes unexplained death can occur, especially in infants with untreated or complex forms of the disease 2.

Progression and Impact on Daily Life

Early symptoms are often dramatic, prompting urgent evaluation. If left untreated or if initial repairs are incomplete, children may experience ongoing limitations in activity, growth, and development. Quality of life can be substantially impaired, especially without definitive surgical correction 2.

Types of Pulmonary Atresia

Pulmonary atresia is not a single disease, but a spectrum of anatomical variations. Accurate classification is essential for planning treatment and predicting outcomes.

Type	Key Features	Prevalence/Examples	Source(s)
PA-IVS	Intact ventricular septum, variable RV size	20–25%	1 2 4 9 10
PA-VSD	With ventricular septal defect, variable collaterals	Most common	2 5 7 8
Complex	Associated with other cardiac malformations	Less common	2 5

Table 2: Classification of Pulmonary Atresia

Pulmonary Atresia with Intact Ventricular Septum (PA-IVS)

PA-IVS is characterized by a complete blockage (atresia) of the pulmonary valve, with no hole (defect) between the ventricles. The right ventricle (RV) is often small or underdeveloped, and the degree of RV hypoplasia greatly influences management 1 4 9 10. The tricuspid valve and coronary arteries may also be abnormal 1 4. PA-IVS is further subdivided based on RV morphology:

• Small (Hypoplastic) RV: Often with well-formed but small tricuspid valve; may have abnormal coronary connections 1 4.
• Normal or Enlarged RV: May be associated with tricuspid valve malformations similar to Ebstein’s anomaly 4.

Pulmonary Atresia with Ventricular Septal Defect (PA-VSD)

PA-VSD features a ventricular septal defect (a hole between the heart’s lower chambers), allowing some mixing of blood and alternative pathways for blood flow to the lungs 2 5 7 8. This type is highly variable:

• With Native Pulmonary Arteries: Blood flow may reach the lungs through native arteries 5.
• With Major Aortopulmonary Collateral Arteries (MAPCAs): Some patients depend on abnormal blood vessels from the aorta to supply the lungs 5 8.
• Without Native Pulmonary Arteries: All lung blood supply comes from MAPCAs 5.

Complex Pulmonary Atresia

This term refers to pulmonary atresia occurring alongside other complex cardiac malformations, such as heterotaxy or single ventricle physiology. These cases are less common but often more challenging to manage 2 5.

Clinical Implications of Classification

Identifying the type of pulmonary atresia helps determine:

• The urgency and nature of surgical intervention
• Prognosis and expected long-term outcomes
• The risk of associated anomalies, such as coronary artery abnormalities in PA-IVS 1 4 10

Causes of Pulmonary Atresia

Understanding what causes pulmonary atresia provides insight into both prevention and future research priorities. While the exact causes are not always clear, recent studies have begun to unravel genetic and developmental contributors.

Cause/Factor	Description	Prevalence/Impact	Source(s)
Genetic mutations	Rare variants in several candidate genes	Emerging evidence	6 12
Chromosomal deletions	22q11 deletion syndrome linked to higher risk	Significant impact	12
Developmental defects	Abnormal valve/tricuspid/coronary development	Common in cases	1 3 4 7
Unknown/Multifactorial	Many cases have no clear single cause	Majority	6 7

Table 3: Causes and Contributing Factors

Genetic and Chromosomal Factors

Recent advances in genetic research have identified several rare mutations in candidate genes (such as DNAH10, DST, FAT1, HMCN1, HNRNPC, TEP1, TYK2) that may play a role in the development of pulmonary atresia 6. Chromosomal deletions, particularly 22q11 (often associated with DiGeorge syndrome), are strongly linked to the PA-VSD subtype and can negatively affect surgical outcomes 12.

Developmental Abnormalities

Most cases are believed to result from developmental errors during fetal heart formation. These include:

• Valve Malformations: Failure of the pulmonary valve to form or open properly 1 3 7.
• Tricuspid Valve Anomalies: May restrict right ventricular growth or affect blood flow 1 4.
• Coronary Artery Changes: Abnormal connections between the right ventricle and coronary arteries, especially in PA-IVS 1 4.

Multifactorial and Unknown Causes

Despite increasing genetic knowledge, the majority of cases still have no identifiable single cause. Environmental factors, random developmental errors, and complex gene-environment interactions likely contribute 6 7.

Importance of Identifying Underlying Causes

Recognizing genetic and syndromic causes is important for:

• Family counseling about recurrence risk
• Planning for associated anomalies or syndromes
• Tailoring surgical and medical management 6 12

Treatment of Pulmonary Atresia

Treatment of pulmonary atresia has evolved dramatically over the past few decades. Management is individualized, based on the defect’s type and severity, as well as the child’s overall health.

Approach	Indication/Details	Outcome/Goal	Source(s)
Initial stabilization	Prostaglandin E1, oxygen, supportive care	Maintain ductal flow	9 10 11
Catheter-based	RF valvotomy, PDA stenting, balloon septostomy	Bridge or definitive	9 10
Surgical shunt	Modified BT shunt, central shunt	Palliative	9 10 11
Definitive repair	Biventricular, 1.5-ventricle, Fontan procedures	Restore circulation	9 10 12
Unifocalization	For PA-VSD with MAPCAs	Establish blood flow	8 12

Table 4: Treatment Strategies

Initial Stabilization

Newborns with pulmonary atresia often require urgent stabilization:

• Prostaglandin E1 Infusion: Keeps the ductus arteriosus open, allowing blood to reach the lungs 9 10 11.
• Oxygen and Monitoring: Supportive measures to optimize oxygen delivery.

Catheter-Based Interventions

For selected patients with a favorable anatomy (especially those with membranous atresia and adequate RV size), radiofrequency (RF) valvotomy can open the atretic pulmonary valve, sometimes providing a definitive solution 9 10. Stenting the ductus arteriosus and balloon atrial septostomy may be performed as bridges to surgery or to improve oxygenation 9 10.

Surgical Approaches

The choice of surgery depends on the anatomy:

• Blalock-Taussig (BT) Shunt: Connects a systemic artery to the pulmonary artery, providing a reliable source of pulmonary blood flow 9 10 11.
• Central Shunt: Used in some cases to augment blood flow.
• Bidirectional Glenn and Fontan Procedures: For patients with very small RVs or single ventricle physiology, staged procedures eventually redirect venous blood directly to the lungs (Fontan circulation) 9 10.

Definitive Repair

Whenever possible, biventricular repair (restoring normal two-ventricle circulation) is the goal 9 10. In children with borderline RV size, a 1.5-ventricle repair may be performed (Glenn shunt plus partial RV function). For those with severely hypoplastic RVs, Fontan-type operations are indicated.

Unifocalization for PA-VSD with MAPCAs

In PA-VSD patients with multiple aortopulmonary collateral arteries, unifocalization gathers these vessels into a reconstructed pulmonary artery system, followed by staged or single-stage complete repair 8 12. This approach has improved survival and outcomes, especially when tailored to pulmonary artery anatomy 8 12.

Outcomes and Prognosis

• Survival: Has improved markedly, with 5- and 10-year survival rates exceeding 80% in some series 10 12.
• Exercise Capacity: Best in those who undergo definitive repair; limitations persist in others 2.
• Genetic Factors: Presence of 22q11 deletion is associated with higher surgical risk and lower survival 12.

Conclusion

Pulmonary atresia is a complex but increasingly treatable congenital heart defect. Early recognition, precise classification, and advances in both surgical and catheter-based therapies have transformed outcomes for affected children. Key points include:

• Symptoms: Cyanosis, rapid breathing, poor feeding, and exercise intolerance are common, often appearing soon after birth.
• Types: Classification into PA-IVS, PA-VSD, and complex forms is essential for management.
• Causes: Both genetic and developmental factors play roles; most cases remain multifactorial or unexplained.
• Treatment: Modern strategies include prostaglandins, catheter-based interventions, surgical shunts, and definitive repairs tailored to individual anatomy.

Pulmonary atresia remains a challenging diagnosis, but with coordinated care and evolving therapies, many children are now able to survive and thrive.