From the Guidelines
Tetralogy of Fallot with pulmonary atresia is indeed often associated with hypoplastic pulmonary arteries, which significantly impacts the management and prognosis of the condition. This severe cardiac malformation includes the four classic features of Tetralogy of Fallot (ventricular septal defect, overriding aorta, right ventricular hypertrophy, and right ventricular outflow tract obstruction), but with complete obstruction (atresia) of the pulmonary valve rather than stenosis, as categorized under Great Complexity (or Complex) in the ACHD AP Classification 1. The pulmonary arteries in TOF-PA are typically underdeveloped (hypoplastic) because blood flow to the lungs during fetal development is reduced or absent. This hypoplasia can vary in severity, from mild narrowing to severely diminished or discontinuous pulmonary arteries.
Key Features of TOF-PA
- The pulmonary circulation in these patients often depends on collateral vessels that develop to supply blood to the lungs.
- Management involves staged surgical repair, which may include initial placement of a systemic-to-pulmonary shunt to promote pulmonary artery growth, followed by complete repair when possible.
- In some cases, rehabilitation of hypoplastic pulmonary arteries may require multiple interventions including balloon angioplasty, stent placement, or surgical reconstruction.
Prognosis and Surgical Approach
- The degree of pulmonary artery hypoplasia significantly impacts long-term prognosis and surgical approach in these patients, as outlined in the 2018 AHA/ACC guideline for the management of adults with congenital heart disease 1.
- Pulmonary atresia, including TOF-PA, is classified as a Great Complexity (or Complex) condition, emphasizing the need for specialized care and consideration of the individual patient's anatomy and physiology when determining the best course of treatment.
From the Research
Tetralogy of Fallot with Pulmonary Atresia
- Tetralogy of Fallot with pulmonary atresia is a complex congenital heart defect characterized by the absence of antegrade flow into the pulmonary arteries 2.
- Patients with this condition often have hypoplastic pulmonary arteries, which can be supplied by aortopulmonary collaterals or native pulmonary artery branches 3, 4, 5.
- The management of tetralogy of Fallot with pulmonary atresia must be individualized to each patient's anatomy and physiology, taking into account the source of pulmonary blood flow and the size and number of collateral arteries 3, 6.
Characteristics of Pulmonary Arteries
- Patients with tetralogy of Fallot and pulmonary atresia often have diminutive pulmonary arteries, which can be rehabilitated with surgical grafts, balloon dilation, and embolization of collaterals 4.
- The pulmonary arterial index can be used to assess the severity of pulmonary artery hypoplasia, with values less than 90 mm²/m² indicating more severe disease 3.
- Central pulmonary arteries can be absent or hypoplastic in some patients, making surgical repair more challenging 5.
Surgical Management
- The goal of surgical management is to establish pulmonary blood flow from the right ventricle with right ventricular pressures that are ideally less than half of the systemic pressure 2.
- Surgical approaches can include single-stage full correction, unifocalization, and right ventricular to pulmonary artery conduit implantation, depending on the patient's anatomy and physiology 3, 5, 6.
- Complete repair can be achieved in a high percentage of patients, with low rates of reoperation and mortality 3, 5.