Unilateral pulmonary artery atresia

Unilateral pulmonary artery atresia (UPAA), also known as unilateral absence of the pulmonary artery (UAPA) or proximal interruption of the pulmonary artery, is a variant of pulmonary artery atresia.

Terminology

The term interruption is preferred by some to absence or atresia because the anomaly pertains only to the proximal pulmonary artery while the distal pulmonary arterial tree is maintained .

Epidemiology

The estimated prevalence is around 1 in 200,000 young adults. The reported frequency on the right side is slightly greater for some reason .

Clinical presentation

Can be variable and include:

• asymptomatic: adult patients with UPAA are often asymptomatic
• chest pain
• pleural effusion
• recurrent chest infections: lack of arterial blood flow to the affected lung may result in poor delivery of inflammatory cells to sites of inflammation and impaired ciliary function
• dyspnea
• reduced exercise tolerance
• pulmonary hypertension
• hemoptysis
• high-altitude pulmonary edema

Pathology

It commonly occurs on the side opposite to that of the aortic arch.

The distal branches of the affected artery usually remain intact and can be supplied by collateral vessels from other arteries such as bronchial, intercostal, internal thoracic, subdiaphragmatic, subclavian, or even coronary arteries.

Associations

It occurs in association with other cardiac anomalies in ~60% of cases:

• septal defects
  • atrial septal defect
  • ventricular septal defect
• coarctation of aorta
• right aortic arch
• truncus arteriosus
• tetralogy of Fallot

In around 40% of cases they occur in isolation, where it is then termed as:

• isolated unilateral absence of the pulmonary artery

Radiographic features

Features can vary depending on which side is affected.

Plain radiograph

May be seen as volume loss to the ipsilateral lung with and overinflation +/- herniation across the midline of the contralateral lung . The affected lung usually appears hyperlucent due to oligemia, whereas the contralateral lung is supplied by a prominent pulmonary artery.

CT

Allows direct visualization of the absence of the affected pulmonary artery. Volume loss to the affected lung is also shown. Extensive collaterals can be visualized. May allow recognition of associated cardiac anomalies.

Complications

Recognized complications include:

• development of pulmonary hypertension
• hemoptysis 
• secondary bronchiectasis from chronic infection 

Treatment and prognosis

Treatment is often around the management of complications in asymptomatic individuals. There is often no commonly accepted consensus on a particular treatment strategy.

History and etymology

It is thought to have been first described by O Frantzel in 1868 .

Differential diagnosis

Plain film differential for small lung includes:

• hypogenetic lung syndrome (scimitar syndrome)
• Swyer-James-MacLeod syndrome
• lobectomy

Siehe auch:

• Pulmonalatresie