Pulmonary atresia

Pulmonary atresia with an intact ventricular septum

This is a relatively rare variant of congenital heart disease (Pulmonary atresia with an intact ventricular septum). The main anatomical feature is complete atresia of the pulmonary valve. It is invariably accompanied by hypoplasia of the right ventricular (RV) cavity and tricuspid valve of varying severity.

The choice of surgical intervention depends directly on the volume and shape of the right ventricular cavity:

• If the RV infundibulum (infundibulum) is preserved, surgeons can perform a biventricular repair.
• If the RV cavity is critically small, single-ventricle physiology is established. In this case, prominent myocardial sinusoids within the right ventricular wall can often be visualized on imaging.

Double Outlet Right Ventricle (DORV)

In this anomaly (Double Outlet Right Ventricle), the aorta and pulmonary artery arise predominantly or entirely from the right ventricle. The left ventricle (LV) lacks its own direct outlet into the great vessels; blood flows from it into the RV via a ventricular septal defect (VSD). Rarely, the VSD is absent, leading to marked LV hypoplasia. The presence of cyanosis in the patient is variable and depends on whether concomitant pulmonary stenosis is present.

Main anatomical variants:

1. «Fallot-type» (Fallot's type): The most frequent variant. The great vessels are normally positioned, and the VSD is in a subaortic position. It is frequently accompanied by pulmonary stenosis, making the clinical presentation resemble tetralogy of Fallot.
2. Taussig–Bing anomaly (Taussig–Bing anomaly): The aorta is located anteriorly, and the VSD occupies a subpulmonary position.

Surgical treatment:

• In Fallot-type: The VSD is closed with a specialized patch that redirects blood flow from the LV into the aorta. Concurrently, the pulmonary stenosis is relieved.
• In Taussig–Bing anomaly: The surgical strategy depends on outflow tract obstruction. If there is no obstruction, the VSD is closed with a patch and an arterial switch operation is performed. If obstruction is present, LV blood flow is tunneled to the aorta through the VSD, and a conduit is placed between the RV and the pulmonary artery (Rastelli procedure).

Truncus arteriosus

Normally, the aorta and pulmonary artery are separated, but in truncus arteriosus (Common Arterial Trunk), a single arterial vessel arises from both ventricles. It overlies a large, malaligned VSD and gives rise to the systemic, pulmonary, and coronary arteries.

Because blood from both ventricles mixes within the common trunk, the patient develops cyanosis. Without surgical treatment, these patients rapidly develop severe progressive pulmonary arterial hypertension. The truncal valve itself is frequently abnormal (stenosis or regurgitation is observed, and leaflets may be trileaflet or quadricleaflet). Approximately 40% of common trunk arches are right-sided and lie in the mediastinum higher than the normal aortic arch.

Classification based on pulmonary artery (PA) branching pattern:

• Type I: A short main PA arises from the common trunk and subsequently divides into the right and left branches.
• Type II: The right and left PAs arise separately from the posterior wall of the common trunk.
• Type III: The right and left PAs arise from the lateral walls of the common trunk.

During surgical repair, the common trunk is reconstructed to serve as the systemic vessel (aorta) arising from the LV. The VSD is closed with a patch, and an artificial conduit is established between the RV and the pulmonary arteries to ensure pulmonary blood flow.

Role of diagnostic imaging and cardiac MRI

Magnetic resonance imaging plays a pivotal role in both surgical planning and postoperative follow-up. The «black-blood» spin-echo sequence (Black-blood spin-echo) provides data that correlate excellently with actual surgical findings.

Preoperative MRI objectives:

• Evaluate the 3D anatomy of great vessel arrangement and the VSD.
• Identify outflow tract obstructions and associated anomalies (e.g., coarctation or interruption of the aortic arch).
• Quantify intracardiac shunts, as well as ventricular mass, volumes, and function.
• For truncus arteriosus: determine the morphological branching type (I, II, or III), and assess truncal valve morphology and function.

Postoperative MRI objectives:

• Assess patch integrity (presence of leaks).
• Evaluate the function of created conduits (homografts).
• Exclude or confirm valvular regurgitation.

Class and exam questions

What else to study on this topic

• Quantitative MRI evaluation of intracardiac shunts (left-to-right and right-to-left)
• Anatomical structure of myocardial sinusoids within the right ventricular wall
• Surgical technique of the Rastelli procedure
• Anomalous pulmonary venous connection and drainage (APVC)
• Assessment of pulmonary vascular disease in unoperated patients

Other topics in the «Chest Radiology» section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.