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37 year old male presented with sudden loss of consciousness following nocturnal micturition with abnormal screening chest X- ray.
20 Jun

37 year old male presented with sudden loss of consciousness following nocturnal micturition with abnormal screening chest X- ray.

Findings

 

A.widening of paratracheal stripe. Hyperinflation of left lung. Volume loss of right lung.

B.Absent right pulmonary artery

C and D - hypertrophic right bronchial arteries with multiple collaterals. Fibrotic and multicystic changes in right lung with reduced volume and compensatory left lung hyperinflation.

UNILATERAL RIGHT PULMONARY ARTERY ATRESIA

Feature Pulmonary Artery Agenesis Pulmonary Artery Atresia
Primary Structural Abnormality Complete absence of one pulmonary artery, including its origin and distal branches Occlusion or failure of continuity of one pulmonary artery, often with distal branches present
Embryologic Basis Failure of the sixth aortic arch to develop the PA and its derivatives Interruption in the proximal sixth aortic arch connection with the pulmonary trunk
Pulmonary Parenchyma Often hypoplastic but present; perfused via systemic collaterals Also hypoplastic; typically perfused via MAPCAs or PDA
Vascular Findings Main PA and hilar branches absent; intrapulmonary arteries may exist and are perfused via systemic collaterals Proximal PA segment may be absent or narrowed; a stump is often present but not always identifiable
Bronchial Anatomy Usually intact; may be hypoplastic in severe agenesis Intact
Imaging Differentiation No PA stump; complete absence of PA from origin to branches; systemic collaterals supply lung; distal intrapulmonary bed may exist but is disconnected PA stump usually present; distal branches may be seen filled via MAPCAs or PDA; however, stump may be absent if atresia occurs early or is complete
Clinical Implications Often asymptomatic; may present with hemoptysis or recurrent infections Similar symptoms; treatment depends on distal PA presence and symptoms

 

  • Congenital absence or severe underdevelopment of one pulmonary artery (usually right), with preservation of the contralateral pulmonary circulation.
  • Failure of the proximal sixth aortic arch to connect with the pulmonary trunk during development.
  • Hemodynamics: Affected lung receives blood via systemic collaterals (MAPCAs) or patent ductus arteriosus (PDA).
  • Associated Conditions: Tetralogy of Fallot, right aortic arch, VSD (if syndromic or complex case)

Chest X-ray (CXR) Findings

  • Affected Side:
    • Small hemithorax with volume loss
    • Absent or diminished hilar vascular markings
    • Mediastinal shift toward affected lung
  • Unaffected Side:
    • Hyperinflation and increased vascular markings
    • Enlarged contralateral pulmonary artery
  • Other Clues:
    • Rib crowding on affected side
    • Elevated hemidiaphragm

CT / CTA Findings

  • Absent Pulmonary Artery:
    • No visualization of one main/branch PA within ~1 cm of expected origin
    • Possible blind-ending PA stump
  • Collateral Circulation:
    • Systemic collaterals (MAPCAs) from bronchial, subclavian, or aortic origins
    • Contrast opacification of pulmonary parenchyma via systemic arteries
  • Lung Parenchyma Changes:
    • Hypoplastic lung with reduced vascularity
    • Bronchiectasis, scarring, or chronic infection features
  • Right vs. Left UAPA:
    • Right UAPA is more common, especially in isolated cases. Left UAPA more often coexists with right?sided aortic arch or complex cardiac defects.

Clinical Relevance & Imaging Role

  • Clinical Presentation:
    • Often asymptomatic in childhood
    • May present with recurrent infections, dyspnea, or hemoptysis
  • Imaging Utility:
    • CXR: Initial suspicion
    • CT Angiography: Defines vascular anatomy, collateral supply, parenchymal effects
    • MRI: Alternative in young patients for functional assessment
    • Echocardiography: Evaluate associated cardiac anomalies

Treatment

  • Treatment Tailored by:
    • Age of presentation
    • Symptomatology
    • Associated cardiovascular anomalies
  • Young Patients:
    • Revascularization (systemic-to-pulmonary artery shunt) if distal PA formed
  • Hemoptysis or Focal Infection:
    • Lobectomy or selective embolization of systemic arterial supply
  • Asymptomatic Adults:
    • Risk of pulmonary hypertension remains
    • Endothelin receptor antagonists may be considered
  • Monitoring:
    • ???????Regular follow-up with pulmonary hemodynamic surveillance recommended

REFERENCES

  • Steiropoulos P, Archontogeorgis K, Tzouvelekis A, Ntolios P, Chatzistefanou A, Bouros D. Unilateral pulmonary artery agenesis: a case series. Hippokratia. 2013;17(1):73–6.
  • Lee EY, Boiselle PM, Cleveland RH. Multidetector CT evaluation of congenital lung anomalies. Radiology. 2008;247(3):632–48.
  • Ten Harkel ADJ, Blom NA, Ottenkamp J. Isolated unilateral absence of a pulmonary artery: a case report and review of the literature. Chest. 2002;122(4):1471–7. doi:10.1378/chest.122.4.1471.
  • Sadikot RT, Suresh MV. Unilateral absence of the left pulmonary artery with an associated vascular anomaly in adulthood. Cureus. 2016;8(3):e527. doi:10.7759/cureus.527.

Dr. DEEPTI H V

CONSULTANT RADIOLOGIST

MANIPAL HOSPITAL , YESHWANTHPUR, BENGALURU

 

Dr. VINEETH BABY

FELLOW IN CROSS SECTIONAL IMAGING

MANIPAL HOSPITAL , YESHWANTHPUR, BENGALURU

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