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A 26-Year-Old Woman With a Small Right Lung and a Right-Sided Heart FREE TO VIEW

Jeffrey Albores, MD; Malcolm Iain Smith, MD
Author and Funding Information

CORRESPONDENCE TO: Jeffrey Albores, MD, Division of Pulmonary and Critical Care Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, Room 37-131 CHS, Los Angeles, CA 90095-1690


Copyright 2016, American College of Chest Physicians. All Rights Reserved.


Chest. 2016;149(3):e91-e94. doi:10.1016/j.chest.2015.08.023
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Published online

A 26-year-old woman presented with abnormal findings on a chest radiograph. She had no significant history other than a fever 4 months prior to presentation that had resolved without a definite cause identified. She denied cough, shortness of breath, chest pain, history of smoking, environmental exposures, or prior pregnancies. She remained physically active.

Figures in this Article

The patient’s vital signs were as follows: blood pressure, 110/80 mm Hg; pulse rate, 70 beats/min; respiration, 16 breaths/min; and oxygen saturation level, 98% on ambient air. Results of her lung examination were normal and clear to auscultation bilaterally. Cardiac examination revealed point of maximal impulse 1 cm to the right of the lower sternal border; normal heart sounds; no murmurs; and no jugular venous distension. There was no cyanosis or edema in her extremities.

A chest radiograph revealed dextrorotation of the heart with decreased right lung volume (Fig 1). A CT scan of the chest is shown in Figure 2. An echocardiogram revealed no pulmonary hypertension, valvular anomalies, septal defects, or congenital heart disease.

Figure 1
Figure Jump LinkFigure 1 Chest radiograph showing dextrorotation of the heart with decreased right lung volume.Grahic Jump Location
Figure 2
Figure Jump LinkFigure 2 CT scan of the chest. A, Transverse thoracic plane at the level of the sternal angle. B, Coronal thoracic plane.Grahic Jump Location

What is the diagnosis?

Diagnosis: Isolated unilateral pulmonary artery agenesis

Unilateral pulmonary artery agenesis (UPAA) is a rare congenital anomaly that is frequently accompanied by cardiovascular anomalies such as tetralogy of Fallot or septal defects; it can also occur as an isolated finding. Prevalence of isolated UPAA is estimated to be 1 in 200,000, and 108 cases were diagnosed between 1978 and 2000. The median age of presentation is 14 years (range, 0.1-58 years), and there is no sex predilection. The pathogenesis of UPAA involves failure of the pulmonary trunk to connect with the sixth aortic arch during embryogenesis. The affected ipsilateral hilum and lung are smaller, possibly due to impaired development of the affected bronchial tree from the abnormal blood supply from systemic collaterals. The affected lung is perfused by persistent embryonic arteries from the aorta or its branches; abnormal collaterals from the bronchial, subclavian, intercostal, or diaphragmatic arteries; or hyperplastic bronchial arteries. Right-sided pulmonary artery agenesis is more common vs left-sided pulmonary artery agenesis.

The presentation of UPAA can range from no symptoms to dyspnea, chest pain, decreased exercise tolerance, pulmonary hypertension, recurrent pulmonary infections, hemoptysis, and high-altitude pulmonary edema (HAPE). Pulmonary infections are usually mild but can also include bronchopneumonia and bronchiectasis from recurrent pulmonary infections. It is hypothesized that recurrent pulmonary infections in UPAA result from impaired mucociliary clearance and reduced delivery of inflammatory cells to the affected lung. Hemoptysis is caused by excessive systemic collateral circulation to the affected lung, and it can be self-limiting for many years or can result in massive pulmonary hemorrhage and death. Pulmonary hypertension represents the main prognostic factor for UPAA, but factors that predispose patients with UPAA to develop pulmonary hypertension remain unclear. Pulmonary hypertension in patients with UPAA can manifest during HAPE or pregnancy. Predisposition to HAPE in patients with UPAA remains unclear.

The diagnosis of UPAA is made via imaging. An abnormal finding on chest radiograph prompts investigations regarding UPAA. Chest radiographs can show absent hilar shadow, ipsilateral hypoplastic lung, ipsilateral mediastinal shift, ipsilateral decreased pulmonary markings, and hyperinflation of the contralateral lung. An echocardiogram is helpful in excluding pulmonary hypertension, valvular anomalies, septal defects, or congenital heart disease. Scintigraphy can evaluate the anatomy of the affected side and the ventilation/perfusion status of the lungs. The constellation of findings in a ventilation/perfusion scan in UPAA consists of reduced perfusion to the whole affected lung coupled with diminished ventilation. CT scans or MRIs of the chest with contrast offer the definitive diagnosis of UPAA because they provide detailed anatomy, can evaluate congenital heart defects, and can also diagnose underlying pulmonary infections and bronchiectasis. Pulmonary angiography remains the gold standard for diagnosis of UPAA, but its use has decreased with the more widespread use of echocardiography, chest CT scans, and MRIs. Pulmonary angiography is reserved for therapeutic purposes such as embolization for hemoptysis or if revascularization is proposed by visualization of hilar arteries.

Management of UPAA is tailored to specific disease presentation. Asymptomatic patients can be monitored serially for disease manifestations. Pulmonary infections are treated with antibiotics. Hemoptysis can be self-limiting for many years, and persistent or massive hemoptysis can be managed with selective embolization of systemic collaterals or pneumonectomy of the affected side. Management of HAPE consists of descent in altitude, supplemental oxygen, and investigation for possible underlying pulmonary hypertension. For pulmonary hypertension, revascularization of the side with the absent pulmonary artery can be performed if there is an identifiable artery at the hilum, which is then reconstructed with a conduit synthetic graft. If revascularization is not possible, pharmacologic treatment for pulmonary arterial hypertension has shown promising results.

The overall mortality rate of UPAA is 7%; mortality results from massive pulmonary hemorrhage, pulmonary hypertension with right-sided heart failure, HAPE, and respiratory failure. Special consideration exists in women who develop pulmonary hypertension during pregnancy, as mortality in this population is high. Female patients are counseled to prevent pregnancy or terminate pregnancy at an early stage in cases of previously known pulmonary hypertension. If the pregnancy is too advanced, extensive evaluation and pharmacologic therapy for pulmonary arterial hypertension may help improve outcomes. Early recognition of UPAA can prevent potentially damaging effects of high altitude or pregnancy.

Clinical Course

A CT scan of the patient’s chest revealed agenesis of the right pulmonary artery with associated hypoplastic right lung supplied by hypertrophied bronchial arteries and dextrorotation of the heart (Fig 2). In retrospect, the fever 4 months prior to presentation could have been related to pulmonary infection, indicated by the scattered ground-glass opacities on the chest CT scan. The patient was counseled on the manifestations of pulmonary artery agenesis and the risks involved with pregnancy and high altitude.

  • 1.

    UPAA is a rare congenital anomaly frequently accompanied by cardiovascular anomalies, or it can occur as an isolated finding.

  • 2.

    Presentations of UPAA can range from an incidental finding in an asymptomatic patient to dyspnea, pulmonary hypertension, recurrent pulmonary infections, hemoptysis, and HAPE.

  • 3.

    A chest CT scan or MRI provides the definitive diagnosis for UPAA.

  • 4.

    Overallmortality in UPAA results from massive pulmonary hemorrhage, pulmonary hypertension with right-sided heart failure, and HAPE.

  • 5.

    Recognition of UPAA can prevent the potentially damaging effects of high altitude or pregnancy.

Financial/nonfinancial disclosures: None declared.

Other contributions:CHEST worked with the authors to ensure that the Journal policies on patient consent to report information were met.


Figures

Figure Jump LinkFigure 1 Chest radiograph showing dextrorotation of the heart with decreased right lung volume.Grahic Jump Location
Figure Jump LinkFigure 2 CT scan of the chest. A, Transverse thoracic plane at the level of the sternal angle. B, Coronal thoracic plane.Grahic Jump Location

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