Anomalous systemic arterial supply to normal lung

Anomalous systemic arterial supply to normal lung is an anatomical variant in which a portion of the lung (usually a basal segment) is supplied by a systemic vessel without a distinct pulmonary sequestration.

Terminology

It was traditionally (perhaps inappropriately since not a true sequestration) called a Pryce type 1 sequestration.

Clinical presentation

Many of these patients are asymptomatic but with time, many patients can develop localized pulmonary hypertension, hemoptysis (considered most common symptom), and high output cardiac failure. 

Pathology

It is thought to arise as a result of the failure of regression of the primitive aortic branches to the developing lung bud. The systemic artery most commonly arises from the thoracic aorta, and less commonly from the abdominal aorta or celiac axis, and even more rarely from the left subclavian and internal mammary arteries.

Subtypes

It can be of two subtypes:

• isolated systemic arterial supply to normal lung (ISSNL)
• systemic arterial supply associated with normal pulmonary artery (dual supply)

Distribution

Basal segments of the left lower lobe are the most commonly affected site ^1-8.

Radiographic features

CT angiography

Shows regions of systemic arterial supply to a normal lung but with no accompanying bronchial sequestration.

Treatment and prognosis

Treatment strategies include:

• surgery (often lobectomy or segmentectomy), when aberrant systemic artery is the sole supply
• occlusion of aberrant vessel by surgical ligation or endovascular treatment (embolization), when the involved segment has both systemic and pulmonary blood supply

See also 

• pulmonary pseudosequestration