EXPERIMENTAL AND THERAPEUTIC MEDICINE 14: 2600-2602, 2017

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3‑Dimensional computed tomography imaging of the ring‑slingcomplex with non‑operative survival case in a 10‑year‑old female
HIRONOBU FUKUDA1, GEORGE IMATAKA1, FABRIZIO DRAGO2,KOSAKU MAEDA3 and SHIGEMI YOSHIHARA1
1

Department of Pediatrics, Dokkyo Medical University, Tochigi, Japan; 2Department of Pediatric Cardiology
and Cardiac Surgery, Pediatric Cardiology and Cardiac Arrhythmia Complex Unit,
Bambino Gesù Children's Hospital and Research Institute, Rome, Italy;
3
Department of Pediatric Surgery, Kobe Children's Hospital, Kobe, Japan
Received May 1, 2017; Accepted July 5, 2017
DOI: 10.3892/etm.2017.4821

Abstract. We report a case of a 10‑year‑old female patient whosurvived ring‑sling complex without surgery. The patient hadcongenital wheezing from the neonatal period and was treatedafter a tentative diagnosis of infantile asthma. The patient
suffered from allergy and was hospitalized several times due
to severe wheezing, and when she was 22 months old, she
was diagnosed with ring‑sling complex. We used a segmental
4 mm internal diameter of the trachea for 3‑dimensional
computed tomography (3D‑CT). Bronchial asthma is considered an exacerbating factor in infantile period and frequently
required treatment with bronchodilator. After the age of 10,
the patient had recurrent breathing difficulties during physicalactivity and during night time, and this condition was assessed
to be related to the pressure from the blood vessel on thering. We repeated the 3D‑CT evaluation later and discoveredthat the internal diameter of the trachea had grown to 5 mm.
Eventually, patient's breathing difficulties disappeared after
the treatment of bronchial asthma and restriction of physicalactivities. Our patient remained in stable condition without
undergoing any surgical procedures even after she passed theage of 10.
Introduction
One of the main causes of wheezing and respiratory distressin newborns and infants is pulmonary sling (1). Pulmonary
sling is a congenital bronchial malformation in which the left
pulmonary artery originates from the right pulmonary arteryand its artery passes between the trachea and the esophagus

Correspondence to: Dr George Imataka, Department of Pediatrics,Dokkyo Medical University, 880 Kitakobayashi, Mibu, Shimotsuga,
Tochigi 321‑0293, JapanE‑mail: geo@dokkyomed.ac.jp

Key words: 3D‑CT, pulmonary sling, lung agenesis, tracheal
stenosis, vascular compression

and leads to the left hilar (2,3). Pulmonary sling may betreated by cardiovascular surgery, and this treatment allows us
to release the pressure of the trachea by reconstructing surgery
on the left pulmonary artery (4). The ring‑sling complex is arare malformation, which complicates the congenital tracheal
stenosis caused by pulmonary sling due to the circumferential
cricoid of the trachea. The prognosis for this condition is relatively poor and this may be explained by the fact that tracheal
stenosis is not lifted, even after surgery on the left pulmonary
artery (4). We studied a 22‑month‑old patient diagnosed withring‑sling complex triggered by recurrent wheezing after birth.
The patient survived until the age of 10 without undergoing
any surgical procedures. In this report, we explain the patient's
clinical course using the results obtained from our examinations with 3‑dimensional computed tomography (3D‑CT)
imaging.
Case report
The patient was born with an emergency caesarean section
with a declining fetal heart rate at 41 weeks gestation. She
weighed 2,860 g at birth with no external congenital abnormality. Although birth asphyxia was not noted, the patient
had repeated wheezing during the neonatal period. When she
was just 3 months old, the patient was hospitalized in anotherhospital and was diagnosed with croup syndrome caused by aviral infection. At 6 months old, she was hospitalized again,
and this time she was diagnosed with a bronchopneumonia
accompanying with RS virus infection. At that time, she wastentatively diagnosed with infantile asthma, and subsequently
she was hospitalized in different occasions because of severe
wheezing and breathing difficulties.
At 22 months, she was admitted to Dokkyo Medical
University due to bronchial asthma and dyspnea. During theexamination, in chest auscultation, wheezing was heard during
both inhalation and exhalation, therefore she was hospitalized
for a more detailed examination. Allergy tests showed positive
RAST reaction to egg antigen, while no abnormality in laryngeal fiber was detected during the examinations conducted in
our otolaryngology department. Cardiac ultrasound revealed
no noticeable cardiac structural abnormality, however, chest

FUKUDA et al: 3D-CT OF THE RING-SLING COMPLEX WITH NON-OPERATIVE SURVIVAL CASE

Figure 1. At 1 year and 10 months of 3D-CT, trachea‑bronchi and congenitaltracheal stenosis was observed. Minimum bronchial inner diameter of thetracheal stenosis is 4 mm and type of tracheal stanosis was segmental type.
3D‑CT, 3‑dimensional computed tomography.

X‑ray showed an enhancement of both side vascular shadows.
Also, the ascending aorta detected on the right side of thetrachea and the bronchus was displaced to the left side. Results
obtained from contrast 3D‑CT examinations, showed someinteresting findings of circumflex aorta and tracheal bronchus
and the patient was diagnosed as ̔ring‑sling complex̓. At thattime, the inner diameter of the most constricted part of the maintrachea was 4 mm (Fig. 1). After she was treated with oxygen,bronchodilator and steroid, her respiratory condition improved
significantly. We studied the indication of the vascular surgery,however our policy was to continue observing her growth, her
respiration and circulation conditions.
When she was 10, the patient started showing breathing
complications. She was aware of the fact that her dyspnea wasdifferent from the asthma symptoms. Breathing complications
appeared during the physical activity, and improved when
the activity was halted and she rested for at least 15 min.
Moreover, she also suffered from recurrent nocturnal dyspnea,
with chest auscultation during the night and this condition wasaccompanied with inspiratory wheezing. She was hospitalized
when these problems occurred more frequently for more than
2 months. Chest X‑ray showed enhanced bilateral vascularshadow accompanied with an increase in pulmonary bloodflow (Fig. 2A). The ascending aorta was located on the rightside of the trachea and the bronchus was displaced to the left

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side, while the thymus was physiologically enlarged at puberty.
Chest 3D‑CT showed a tracheal bronchus, anomalous originof the left pulmonary artery, pulmonary artery sling, rightaortic arch, right inferior vena cava remnant, and mild tracheal
stenosis. Chest contrast 3D‑CT also revealed narrowing of
the tracheal lumen where the left pulmonary artery crossed
behind the trachea. However, CT did not reveal any obvious
exacerbation of tracheal stenosis, and the minor axis was
5 mm (Figs. 2B and C, and 3). Her bronchial asthma stabilizedwith medication.
The cause of dyspnea was diagnosed to be linked to bloodvessel pressure caused by the vascular rings triggered by conditions such as bronchial asthma, common cold, exercise andnight time sleep. As a result, we initially considered surgicalintervention, but interestingly, her breathing problems disappeared after the treatment of bronchial asthma and a reductionin physical activities. Meanwhile, we carefully and thoroughly,
monitored the patient's breathing and circulation conditions.
Discussion
Ring‑sling complex is a rare but potentially life‑threatening
disorder that often leads to severe respiratory insufficiency,
particularly in neonates and infants (5,6). Although it has
been reported that symptoms can be alleviated without
surgery (6,7), surgical intervention is often required insymptomatic patients (4,5,7). As a pre‑evaluation step before
reconstructive surgery on trachea malformation and stenosis,
3D‑CT examination is considered to be a valuable tool.
Kagadis et al (4) wrote about the usefulness of 3D‑CT forcongenital tracheal stenosis and tracheal malformations. The
clinical course in our case seemed to have dyspnetic symptom
due to the pressure of the main trachea by the vascular ringfrom the neonatal period. 3D‑CT showed that our patient had
a tracheal inner diameter of 4 mm at 22 months old. Tracheal
stenosis of pulmonary sling usually ranges from segmental
type to generalized type, and luckily our case had a segmental
type. Her bronchial asthma was an exacerbation factor, butby managing the bronchial asthma, she grew past the infancy
period. Problematic breathing outbreaks were regularly
observed after the age of 10, however, 3D‑CT showed that her
internal trachea diameter was grown to over 5 mm. Typically,ring‑sling complex cause wheezing throughout the early stages

Figure 2. (A) In the chest X‑ray at the age of 10, the bronchi is deviated to the left side and hypertrophy of the thorax is observed. (B and C) The right aorticarch where the ascending aorta is located on the right side of the trachea and the pulmonary artery sling heading toward the hilar side through the posteriorside of the trachea.

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EXPERIMENTAL AND THERAPEUTIC MEDICINE 14: 2600-2602, 2017

Figure 3. (A and B) There is a bronchus diverging from the right main bronchus and heading towards the upper right lobe. The minimum inner diameter of
the tracheal constriction of the segment is 5 mm. (C and D) A right aorta with an abnormality in the origin of the left subclavian artery is observed. The rightinferior vena cava remnant is recognized.

of infancy, which can be fatal in the case of young infants (8,9).
There are other studies reporting that some patients may reachadulthood without any surgical intervention while their conditions are monitored closely (10). There are some ring‑slingcomplex cases in which the prognosis does not improve by
surgery, and there a small group that can manage to survive
without any surgical intervention.
We will continue our monitoring and evaluating the condition of trachea and surrounding blood vessels, and, of course,
we would consider surgical intervention should respiratory
problems intensify. We concluded that in the case of congenital wheezing under diagnosis of ring‑sling complex during
early infantile stage, it is necessary to carefully determine
the necessity of surgical intervention by evaluating the innerdiameter of the trachea by congenital tracheal stenosis using
radiological technique with 3D‑CT.
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