Isolated unilateral absence of pulmonary artery

Isolated unilateral absence of the pulmonary artery (IUAPA) is the congenital absence of the left or right pulmonary artery.  When found in combination with other congenital vascular abnormalities it is known as unilateral absence of the pulmonary artery (UAPA).

Unilateral absence of the pulmonary artery (UAPA) is a rare clinical condition affecting <0.3% of the population. Isolated unilateral absence pulmonary artery (IUAPA) accounts for 40% of such cases. 

IUAPA is often associated with congenital heart conditions and usually diagnosed in early childhood.  IUAPA may also present in adults with the following symptoms:

UAPA is thought to be due to failed migration and rotation of the primitive sixth aortic arch resulting in agenesis of the pulmonary artery.

The pathogenesis of recurrent bronchopneumonia is thought to be due to hypoperfusion, V/Q mismatch, reduced mucosal defence, and possibly protease-antiprotease imbalance.  Haemoptysis is caused by excessive collateral circulation.

Whilst isolated UAPA is not associated with other clinical conditions, UAPA may be associated with the following vascular abnormalities:

  • ipsilateral contracted lung / small hemithorax
  • mediastinal and tracheal shift toward the affected side
  • ipsilateral hemidiaphragm elevation
  • absent hilar shadow / pulmonary artery
  • ipsilateral diminished pulmonary vascular markings
  • contralateral lung hyperinflation and prominent pulmonary artery
  • absent air trapping on expiratory film
  • absence of the artery
  • pulmonary hypertension
  • associated cardiac anomalies
  • diminished pulmonary vessels
  • bronchiectasis secondary to recurrent bronchopneumonia

On V/Q scintigraphy (quantitative):

  • absence of the pulmonary artery
  • presence of the pulmonary trunk and contralateral pulmonary artery
  • pulmonary capillary wedge pressure
  • pulmonary capillary wedge angiography (looking for hidden hilar arteries)

Treatment options include:

  • revascularisation surgery
  • pulmonary vasodilator therapy (for pulmonary hypertension)
  • pneumonectomy or lobectomy
  • embolisation of collateral haemorrhage

Pulmonary hypertension and haemoptysis confer a poorer prognosis.

On imaging consider:

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Article information

rID: 14188
Systems: Vascular, Chest
Tag: cases
Synonyms or Alternate Spellings:
  • Proximal interruption of the pulmonary artery
  • Isolated unilateral absence of the pulmonary artery (IUAPA)
  • IUAPA
  • Isolated unilateral absence of pulmonary artery (IUAPA)
  • Isolated unilateral pulmonary artery atresia

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