Anomalous systemic arterial supply to normal lung

Anomalous systemic arterial supply to normal lung is an anatomical variant where a portion of the lung (usually a basal segment) gets 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 presenationpresentation

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

Pathology

It is thought to arise as a result of 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 coeliac 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 accompanying no bronchial sequestration.

Treatment and prognosis

Treatment strategies include:

• surgery (often lobectomy and segmentectomy), when aberrant systemic artery is the sole supply
• occlusion of aberrant vessel by surgical ligation or endovascular treatment (embolisation), when the involved segment has a dual to multiple blood supply

See also 

• pulmonary pseudosequestration