Advances in Computed Tomography, 2012, 1, 17-20 Published Online December 2012 (
Left Pulmonary Artery Sling Associated with Patent
Ductus Arteriosus and Atrial Septal
Defect: Evaluation with Multidetector CT
Rukeshman Shakya, Jianhua Liu, Xiaolin Xu, Mohit Godar, Qinghai Yuan
Department of Radiology, The Second Hospital of Jilin University, Changchun, China
Received October 16, 2012; revised November 18, 2012; accepted November 26, 2012
We report a case of left pulmonary artery sling associated with patent ductus arteriosus and atrial septal defect in a
21-month-old child. 256-slice MDCT provides valuable information, such as abnormal origin of the left pulmonary ar-
tery, the relationship between pulmonary artery and airway, the diameter of the patent ductus artery and atrial septal
defect. The information is helpful in d iagnosis, pre-operative evaluation and post-operative follow-up of LPS.
Keywords: Left Pulmonary Artery Sling; Patent Ductus Arteriosus; Atrial Septal Defect; Multidetector CT;
CT Angiography
1. Introduction
The left pulmonary artery sling (LPS) is a rare congenital
abnormality, and is defined as that the LPA arising from
the posterior aspect of RPA, crossing over the right
mainstem bronchus near its origin, and coursing leftward
between the trachea and esophagus to enter the left
hemithorax. Atrial Septal Defect (ASD) is a congenital
heart disease in which abnormal blood flows between left
atrium and right atrium through defect in interatrial sep-
tum. Patent Ductus Arteriosus (PDA) is heart problem
that occurs due to abnormal blood flow between aorta
and pulmonary artery caused by persistent ductus arteri-
osus (tube) which didn’t close soon after child birth or
after few days.
The clinical manifestations of left pulmonary artery
sling are mild or occasional stridor, breathless, inspira-
tory and expiratory rhonchi, productive cough, cyanosis,
difficulty in feeding. It is due to external compression of
trachea or severe compression from complete tracheal
rings. Hypoplasia of entire tracheobronchial tree or res-
piratory distress with pneumonia, atelectasis, intercostal
recession or air trapping may occur. When it is associ-
ated with ASD and PDA, patient can present with short-
ness of breath, swelling of limbs, systolic ejection mur-
mur, wide splitting of P2, accentuation of right precordial
thrust, hoarse cry, cough, lower respiratory tract infec-
tions, failure to thrive, tachypnea, atelectasis or pneumo-
nia. We report a rare case of LPS associated with patent
ductus arteriosus and atrial septal defect.
2. Case Report
A 21-month-old child presented to the pediatric depart-
ment with recurrent cough for half a year and aggrava-
tion of the symptoms with wheezing for 3 days. She was
admitted after being diagnosed with lobar pneumonia on
chest radiography and CT (Figures 1(a)-(c)). The medi-
cal history revealed recurrent episodes of productive cough
with fever, and on auscultation, continuous systolic mur-
mur was heard along the upper left sternal border. Echo-
cardiography showed a patent ductus artery (PDA) and
atrial septal defect (ASD) (Figures 1(d) and (e)).
Two weeks later, after recovery from pneumonia
(Figure 1(f)), the patient was transferred to the depart-
ment of cardiac surgery. CT angiography (CTA) was
done using a 256-slice MDCT scanner both for diagnos-
tic and pre-operative evaluation (Figures 2(a)-(e)). CTA
showed a left pulmonary artery sling (PAS) associated
with PDA and ASD. During surgery, the pulmonary ar-
tery and aorta were separated and the patent ductus arte-
riosus was doubly ligated and divided. The left pulmo-
nary artery was dissected circumferentially to the hilar
branches, and then anastomosed to the origin of PDA
(Figure 2(f)). The ASD was also repaired. Two weeks
later, the patient was discharged without complication.
The case report was approved by the patient’s parents.
3. Discussion
Aberrant left pulmonary artery (LPA) from the right
pulmonary artery (RPA) is arare congen ital abnormality.
opyright © 2012 SciRes. ACT
Figure 1. (a) Chest radiograph posteroanterior view shows prominent plumonary arterial segment (curved black arrow),
patchy density in the le ft lower field (white arrow ) and right upper field (c urved white arrow); (b) CT axial view shows high
density of the right upper lobe (arrow); (c) CT axial view shows irregular high density of the left lower lobe (w hite arr ow ); (d)
The color ultrasound shows PDA (curved white arrow), enlarged pulmonary trunk (white arrow) and normal aorta (white
star); (e) The color ultrasound shows a obvious left-to-right shunt (white arrow) from left atrium (white star) to right atrium
(curved white arrow); (f) CT axial view shows normal left lowe r lo be aft er treatmen t.
Figure 2. (a) CTA axial view shows left pulmonary artery from the right pulmonary artery (white arrow) and slightly stenosis
of the trachea, the diameter of plumonary trunk is 23.6 mm; (b) Multiplanar reconstruction (MPR) CTA image shows the
patent ductus arte ry (white arrow ) and enlarged plumonar y trunk (curve d white arrow); (c ) CTA axial view shows the atrial
septal defect (arrow ); (d) Volume rendering image shows the LPS (white star), enlarged plumonary trunk (cur ved white ar-
row), the patent ductus artery (white arrow); (e) Volume rendering image shows the slightly stenosis of the trachea (curved
hite arrow); (f) Volume rendering image shows left pulmonary artery from the pulmonar y trunk (white star). w
Copyright © 2012 SciRes. ACT
The concept of vascular sling was first introduced for
differe nt iation fr om vascular ri ng.
According to the location of the LPS, it is classified
into two types [1]. The type 1 is defined by the location
of the LPS (levels of T4-T5), then regarding the course
of the tracheal bronchus (TB), the type 1 is divided into
subtype 1A (the course of TB is normal) and subtype 1B
(with additional upper TB). Type 2 is defined by a more
caudal location of LPS (level of T6) and then according
to the existence of the right upper lobe bronchus. Type 2
is further classified into subtype 2A (with normal upper
lobe bronchus) and subtype 2B (without existence of
upper lobe bronchus). Because of the lower location of
the LPS, one to three pulmonary lobes are supplied by a
single bronchus arising fr om the left bron chus, and this is
known as “bridging bronchus”. Our case belongs to the
subtype 1B .
Multidetector CT is recent technical advance in helical
CT imaging. It is performed by moving the patient table
through the CT gantry at a constant speed during con-
tinuous scanning with x-ray tube rotating around the pa-
tient and includes multiple rows of detector rings. It al-
lows acquisition of thin multiple slices creating isotropic
voxels from which reconstruction of image can be done
in different anatomic planes without loss of resolution.
CT Angiography is a diagnostic test that uses CT scanner
and contrast materials which is administered as rapid
bolus through a small catheter placed in a vein of the arm.
CT scan is then performed during contrast material flows
through the blood vessels to various organs which will
increase CT numbers of blood vessels and can be isolated
from low density structures producing 3-dimensional
images of the blood vessels and su rrounding tissues after
reconstructed in different planes by usin g c omputer.
Radiologic examinations play an important role in dia-
gnosis of LPS. Usually a multi-modality approach, such
as chest radiograph y, echocardiography, esophagogr aphy,
computed tomography angiography (CTA), and magnetic
resonance angiography (MRA) are used for diagnostic
work-up [2]. CTA and MRA have almost replaced con-
ventional ang iography for diagnosis, and the sens itivities
of these techniques are nearly 100% [3]. Although MRA
has advantage of non-ionizing radiation exposure, MRA
usually needs long scan time requiring deep conscious
sedation or anesthesia in uncooperative children. MRA
also has a limited role in visualization of the airway and
lung parenchyma. However, CTA can reduce the scan
time significantly to nearly 2.0 sec with conventional
helical protocol and 3.95 sec with prospective ECG-gat-
ing protocol as in our case. CTA also has advantage of
evaluating the trachea. CTA shows detailed information
of the relationship between pulmonary artery and airway
with post processing techniques as in this case. CTA is
also helpful in pre-operative evaluation and post-opera-
tive follow-u p [4]. Although CTA bears th e burden of ra-
diation exposure, a variety of techniques had been used
to reduce the radiatio n dose [5].
There are no adverse effects which could be seen in
this patient. But there maybe adverse effect, one is about
the radiation dose, because the children are more sensi-
tive to the radiation dose in comparison to the adult.
However, the benefit from CTA is more than the adverse
effect as mentioned to pre-operation evaluation.
Management of LPS is based on anatomical classifica-
tion and symptoms. Asymptomatic Type 1 patients can
be followed clinically, and those with respiratory symp-
toms are appropriate for surgery [6]. Because of the
lower mortality and morbidity than other techniques,
slide tracheoplasty is currently regarded as the choice of
surgical repair [7].
The prognosis of PAS is variable according to clinical
presentation. Asymptomatic patients have an excellent
prognosis compared with symptomatic patients [8]. Fiore
et al. [9] reported a 79% survival rate in patients with
4. Conclusion
CTA with its multi reconstruction techniques is a valu-
able tool for diagnostic, pre-operative evaluation and
post-operative follow-up of LPS.
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