Pulmonary Sequestration

Pulmonary sequestration is a congenital mass of dysplastic, non-functioning lung tissue. It has no normal connection to the tracheobronchial tree and receives blood from the systemic circulation rather than from the pulmonary arteries. The feeding artery most often arises from the thoracic or abdominal aorta, and less often from other systemic vessels such as the celiac, intercostal, or subclavian arteries. It is thought to develop from an accessory lung bud arising from the primitive foregut; for the intralobar form, some authors also propose that repeated infection contributes to the abnormal vessels. The abnormal tissue is not simply “extra lung.” Because it lacks normal airway drainage and mucociliary clearance, retained secretions and infection can recur. Because its arterial inflow is systemic, the feeding vessel carries substantially higher pressure than a normal pulmonary artery, and chronic exposure to that pressure can make the feeder dilated or even aneurysmal. Both features explain the two classic later presentations: repeated focal pneumonia and haemoptysis. The anatomic type predicts the physiology and the likely operation: - Intralobar sequestration (ILS) lies within the same pleural covering as...