Case Author(s): Samuel Wang, M.D. and Barry A. Siegel, M.D. , . Rating: #D3, #Q3

Diagnosis: Pulmonary sling.

Brief history:

18-year-old male patient with sickle-cell anemia who presented with chest pain.


Perfusion images.

View main image(vq) in a separate image viewer

View second image(vq). Posterior ventilation images.

View third image(xr). PA chest radiograph.

View fourth image(xr). Lateral chest radiograph.

Full history/Diagnosis is available below

Diagnosis: Pulmonary sling.

Full history:

18-year-old male patient with sickle cell anemia who presented with atypical mid sternal chest pain after being seated for multiple hours. He was noted to be hypoxic on room air.


Xe-133 gas and Tc-99m MAA


The ventilation images demonstrate Xe-133 retention at the right lung base. The perfusion images demonstrate decreased perfusion to the right lung base, matching the ventilatory abnormality. Additionally, there is diffuse hypoperfusion of the entire left lung. The chest radiograph demonstrates mild cardiomegaly with H-shaped vertebrae and bony sclerosis consistent with the patient's sickle cell anemia. No confluent infiltrates or pleural effusions were identified.


The matched perfusion defects in the right lower lung were felt to be most likely due to focal obstructive disease. The differential diagnosis offered for unilateral decreased perfusion without corresponding ventilatory abnormality included an unusual presentation of pulmonary thromboembolism (acute or chronic in situ thrombosis related to the patient's sickle cell anemia), extrinsic compression of the left pulmonary artery due to tumor or inflammatory lymphadenopathy, pulmonary artery hypoplasia, or vasculitis such as Takayasu's arteritis.


A pulmonary arteriogram was performed and demonstrated a pulmonary vascular sling with the aberrant left pulmonary artery arising from the right pulmonary artery. An area of moderate compression was seen in the left pulmonary artery just proximal to the bifurcation of the upper and lower lobe vessels. The presence of a pulmonary sling was also confirmed by a CT study. Review of the patient's chest radiograph demonstrates the posterior tracheal indentation and anterior esophageal impression seen with an aberrant left pulmonary artery.

A pulmonary sling, also known as aberrant left pulmonary artery, represents failure of development of the left 6th aortic arch followed by development of a collateral branch of the right pulmonary artery to supply the left lung. Typically, the left pulmonary artery passes above the right mainstem bronchus and between the trachea and esophagus to supply the left lung. This anomaly can cause obstructive pulmonary disease with stridor being the most common presentation.

View followup image(an). Pulmonary arteriogram

ACR Codes and Keywords:

References and General Discussion of Ventilation Perfusion Scintigraphy (Anatomic field:Heart and Great Vessels, Category:Normal, Technique, Congenital Anomaly)

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Case number: vq018

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