What are the characteristics of arterial supply and venous drainage in intralobar pulmonary sequestration?

Arterial Supply and Venous Drainage of Intralobar Pulmonary Sequestration

Intralobar pulmonary sequestration is characterized by systemic arterial supply typically from the thoracic or abdominal aorta, with venous drainage occurring through the pulmonary venous system to the left atrium.

Arterial Supply Characteristics

Intralobar pulmonary sequestration (IPS) represents abnormal lung tissue that lacks normal communication with the tracheobronchial tree and receives its blood supply from systemic circulation rather than the pulmonary arterial system.

Arterial Supply Patterns:

• Primary arterial supply: Most commonly (74%) from the descending thoracic aorta 1
• Alternative sources:
  • Abdominal aorta
  • Celiac trunk
  • Splenic artery
  • Intercostal arteries
  • Subclavian artery
  • Rarely from coronary arteries 2

Key Arterial Features:

• The systemic feeding artery typically traverses the diaphragm and courses through the inferior pulmonary ligament 3
• Multiple feeding vessels are present in approximately 15% of cases 1
• Arterial vessels are often large and can pose significant bleeding risk during surgical resection

Venous Drainage Characteristics

The venous drainage pattern is a key distinguishing feature between intralobar and extralobar sequestration:

Venous Drainage Pattern:

• Primary drainage: Through the pulmonary veins to the left atrium 4
• This contrasts with extralobar sequestration, which typically drains via systemic veins

Clinical Significance of Venous Drainage:

• The pulmonary venous drainage creates a left-to-right shunt
• In cases with substantial shunting, this can lead to volume overload of the right heart, similar to the physiological effect of an atrial septal defect 4
• Unlike anomalous pulmonary venous connections, there is no potential for right-to-left shunting 4

Diagnostic Imaging Considerations

Accurate identification of vascular anatomy is critical for surgical planning:

Recommended Imaging:

• CT angiography (CTA): Provides excellent spatial resolution for identifying the number, size, and distribution of feeding vessels 4
• MR angiography (MRA): Useful for detailed delineation of vascular anatomy without radiation exposure 4
• Conventional angiography: May be performed as part of pre-surgical embolization but is not routinely used for initial diagnosis 3

Imaging Pitfalls:

• Failure to identify all feeding vessels can lead to catastrophic intraoperative hemorrhage
• Pre-operative embolization of feeding vessels may be considered to reduce surgical risks, particularly for VATS approaches 3

Clinical Implications

The unique vascular supply and drainage of intralobar pulmonary sequestration have important clinical implications:

• The systemic arterial supply creates a left-to-right shunt that can lead to heart failure if significant
• The abnormal vessels can cause hemoptysis due to high-pressure systemic flow
• Surgical resection must address the systemic feeding vessels carefully to prevent hemorrhage
• Preoperative identification of all feeding vessels is essential for safe surgical planning

Understanding these vascular characteristics is crucial for proper diagnosis and management of intralobar pulmonary sequestration, particularly when planning surgical intervention.