The bridging bronchus and pulmonary artery sling
To the Editor,
A 5-month-old male baby was brought to the emergency room with a one-day
history of respiratory distress, wheezing, vomiting, and high fever.
Wheezing had been present since birth but had recently become more
frequent and intense, occurring even at rest. The baby was born
full-term by cesarean delivery and had a medical history of gallbladder
agenesis, secundum atrial septal defect (ASD), and cryptorchidism.
Physical examination showed prolonged expiration and crackling sounds in
the lungs. Vital signs were as follows: fever; 36.4, heart rate; 150,
respiratory rate; 55, blood pressure; 90/55, and oxygen saturation on
room air; 93%. Laboratory tests showed an elevated c-reactive protein
(CRP) level of 5 mg/dL (reference <0.5 mg/dL) and a NT-proBNP
(n-terminal pro-brain natriuretic peptide) level of 596 pg/mL (reference
<125 pg/mL). The patient was hospitalized in the pediatric
intensive care unit. Chest radiograph showed volume loss and decreased
bronchovascular shadows in the left lung, and prominent right pulmonary
vascular structures (Figure 1). Contrast-enhanced chest computed
tomography (CT) was obtained. Chest CT revealed right pulmonary artery
stenosis and a pulmonary artery sling (PAS), in which the left pulmonary
artery (LPA) originates from the right pulmonary artery (RPA) and then
forms a partial ring around the left main bronchus (LMB). There was a
significant compression and stenosis of the LMB due to the PAS (Figure
2A, 2B). Moreover, CT showed left lower lobe pneumonia and an abnormal
bronchus that originated from the LMB and extended to the right middle
and lower lobes, indicating a bridging bronchus (BB) anomaly (Figure 2C,
2D, and 3). The patient was treated with antibiotics and
bronchodilators, and the clinical symptoms regressed. Surgery was
recommended for the pulmonary artery sling and bridging bronchus
anomaly, but the family said they needed time to consider it, and the
patient was discharged.
Bridging bronchus (BB) is a rare congenital anomaly where there is an
anomalous bronchus to the right lung arising from the left main
bronchus. Patients commonly present with signs and symptoms related to
large airway obstruction, such as wheezing, respiratory distress,
stridor, and recurrent respiratory tract infections, as in the present
case. A total of five types of BB have been defined by Henry et al.
according to the origin of the BB and the presence of pseudocarina (1).
The present case fulfills the criteria of Type I BB, which is the most
common form. BB is a potentially life-threatening condition and usually
associated with tracheobronchial anomalies such as congenital
long-segment tracheal stenosis and is generally accompanied by
congenital cardiovascular anomalies, including left pulmonary artery
sling, atrial septal defect (ASD), ventricular septal defect (VSD),
tetralogy of Fallot, and coarctation of the aorta (CTS). The most common
site of airway stenosis is the LMB, as in the present case (1, 2).
Treatment for BB involves surgical intervention, and the timing and
extent of surgery depend on the severity of the airway obstruction, the
presence of associated anomalies, and the patient’s clinical status. The
surgical options for bridging bronchus include resection of the
anomalous bronchus, reconstruction of the affected airway, and
correction of any associated cardiovascular anomalies (1).
Pulmonary artery sling (PAS) is a rare congenital anomaly where the LPA
originates from the RPA and wraps around the trachea and/or bronchi (3).
This results in a significant compression of the airways, which can lead
to respiratory distress and recurrent respiratory infections, as in the
present case. PAS is often associated with other congenital anomalies,
including tracheobronchomalacia, BB, vascular rings, and cardiovascular
defects such as tetralogy of Fallot and patent ductus arteriosus. The
diagnosis of PAS can be challenging, and imaging studies such as CT and
MRI are typically necessary to confirm the diagnosis (4). Surgical
intervention is usually required to relieve the compression of the
airways and prevent further respiratory complications. With appropriate
management, most patients with pulmonary artery sling can expect a good
outcome (3, 4).
In conclusion, this case typically shows the association of BB and PAS
in a baby with respiratory distress, which requires immediate management
in the pediatric intensive care unit.