AJR 2005; 185:150-153
© American Roentgen Ray Society
An Unusual Case of Systemic Arterial Supply to the Lung with Bronchial Atresia
Prachi P. Agarwal1,
Fred R. Matzinger1,
Jean M. Seely1,
Pasteur Rasuli1 and
Farid M. Shamji2
1 Department of Diagnostic Imaging, The Ottawa Hospital, Civic Campus, 1053
Carling Ave, Ottawa, ON, Canada K1Y 4E9.
2 Division of Thoracic Surgery, The Ottawa Hospital, Civic Campus, Ottawa, ON,
Canada K1Y 4E9.
Received June 29, 2004;
accepted after revision September 13, 2004.
Address correspondence to F. R. Matzinger
(fmatzinger{at}ottawahospital.on.ca).
Introduction
We wish to report an unusual case of systemic arterial supply to the
lung with coexistent congenital bronchial atresia identified on a
contrast-enhanced MDCT scan. This is a rare and interesting anomaly within the
pulmonary sequestration spectrum that differs considerably from the classic
description of sequestration. A confident diagnosis on CT scan allowed for
nonoperative treatment with embolization of the systemic artery. This case
also highlights the utility of the alternative classification of
bronchopulmonary-vascular malformations (BPVM) described by Clements and
Warner [1].
Case History
A 31-year-old man who was a lifelong non-smoker developed hemoptysis not
associated with pulmonary sepsis or systemic symptoms. There was no history of
contact with tuberculosis. Physical examination was unremarkable.
A chest radiograph (Fig. 1A)
revealed an abnormal tubular opacity in the left lower lobe of the lung along
with hyperlucency of that lobe. Noncontrast CT performed at another
institution raised the possibility of an arteriovenous malformation (AVM). We
obtained a pulmonary arteriogram that showed diminished pulmonary arterial
supply to the left lower lobe (Fig.
1B). An aortogram revealed an aberrant systemic artery arising
from the descending thoracic aorta and supplying the basal segments of the
left lower lobe. Selective arteriography of this aberrant artery showed venous
drainage into the left atrium by the left inferior pulmonary vein
(Fig. 1C).
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Fig. 1C —31-year-old man with systemic arterial supply to lung and
with bronchial atresia. Aortogram reveals aberrant systemic artery arising
from lower thoracic aorta and supplying left lower lobe. Venous drainage is
seen into inferior pulmonary vein.
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To evaluate the lung parenchyma, bronchial branching pattern, and vascular
anatomy, multidetector contrast-enhanced CT (LightSpeed Plus, GE Healthcare)
was performed using 2.5-mm slice thickness reconstructed at 1 mm. For maximum
opacification of the pulmonary arterial system, 100 mL of nonionic contrast
medium (Omnipaque 300, Amersham Health) was injected at 4 mL/sec. The CT scan
confirmed the presence of an anomalous systemic artery (measuring 1 cm in
diameter) arising from the descending thoracic aorta at the tenth thoracic
vertebral level, supplying the basal segments of the left lower lobe
(Fig. 1D). The pulmonary
arterial supply to the superior segment of the left lower lobe was normal.
However, distal to the superior segmental branch, the artery was hypoplastic
extending to the anterior-medial and lateral segments of the lower lobe, and
the major supply to the basal segments was recruited from the aberrant
systemic artery. The venous drainage was normal through the inferior pulmonary
vein. The complex vascular anatomy was well demonstrated on the maximum
intensity projection image (Fig.
1E). In addition to the vascular anatomy, the CT scan showed
decreased attenuation in the left lower lobe, which was fairly sharply
demarcated from the normal-appearing lung and a tubular nonenhancing structure
closely related to the aberrant artery in keeping with a bronchocele (Figs.
1F and
1G). Both the dilated bronchus
and the hypoattenuating left lower lobe were best seen on volume-rendered
images (Fig. 1H).
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Fig. 1D —31-year-old man with systemic arterial supply to lung and
with bronchial atresia. Contrast-enhanced CT scan (axial image) shows vascular
enhancement of anomalous systemic artery arising from aorta.
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Fig. 1E —31-year-old man with systemic arterial supply to lung and
with bronchial atresia. Maximum intensity projection image shows close
relationship between aberrant systemic artery (black arrow), inferior
pulmonary vein (thin white arrow), and bronchocele (curved
arrow). Left pulmonary artery and its branches (thick white
arrow) are also shown.
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Fig. 1F —31-year-old man with systemic arterial supply to lung and
with bronchial atresia. Axial CT scan through lower lobe shows aberrant
systemic artery (thick arrow) along with fluid-density tubular
branching structure-bronchocele (thin arrow).
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Fig. 1G —31-year-old man with systemic arterial supply to lung and
with bronchial atresia. Axial CT scan (lung window) shows bronchocele in left
lower lobe with fairly well-demarcated hypoattenuating lung parenchyma.
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Fig. 1H —31-year-old man with systemic arterial supply to lung and
with bronchial atresia. 3D volume rendering of airways and lung parenchyma
(upper threshold, -400 H; lower threshold, -800 H) shows overinflated left
lower lobe with dilated bronchus (arrow).
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This patient has a complex bronchopulmonary vascular malformation that is
distinct from the classic description of sequestration and is best classified
as a bronchoarterial malinosculation reported by Clements and Warner
[1]. The bronchopulmonary
abnormality is a congenital bronchial atresia showing characteristic features
of retained secretions in dilated bronchus distal to atresia and overinflation
of lung secondary to entrapment of air admitted via collateral drift. The
arterial abnormality is a systemic artery supplying the otherwise normal left
lower lobe.
A therapeutic transcatheter embolization of the aberrant systemic artery
from the distal thoracic aorta was performed. The aberrant artery was
selectively catheterized and four coils (two 5-mm and two 8-mm coils) were
deployed proximally to obliterate the artery. The postembolization arteriogram
showed occlusion of the feeding artery beyond the coils. There were no
immediate postembolization complications. The patient presented to the
emergency department 2 weeks later with self-limiting left chest pain, and
serial chest radiographs showed features consistent with a left lower lobe
infarct. Follow-up dynamic CT (3 months postprocedure) demonstrated the
thrombosed aberrant systemic artery with distal atelectasis and scarring
representing a zone of infarction. A ventilation-perfusion scan
(Fig. 1I) was obtained 5 months
after the procedure and showed only a small, matched ventilation-perfusion
defect in the left lower lobe.
Discussion
Congenital anomalies of the bronchopulmonary airway and vasculature are a
varied and complex group, and several attempts have been made to classify
them. Pryce [2] first described
sequestration as a "disconnected (dislocated, ectopic) bronchopulmonary
mass or cyst with an anomalous systemic arterial supply." However, four
of the seven cases differed from Pryce's original description of sequestration
[1].
Our case differs from classic sequestration in that there is no abnormal
bronchopulmonary mass or cyst. The lung supplied by the aberrant systemic
artery is normal apart from overinflation and the presence of a bronchocele
(as a result of coexistent bronchial atresia).
Since the first description of sequestration, the terminology has become
increasingly confusing as many variants have been recognized that do not
fulfill the original definition. Hence, Sade et al.
[3] introduced the concept of
"sequestration spectrum," thereby including various combinations
of abnormal bronchial connection, arterial supply, and venous drainage under
an umbrella term.
In 1987, Clements and Warner
[1] proposed a simple
descriptive anatomic approach to such complex BPVMs and coined the term
"malinosculation," which means a "congenitally abnormal
connection or opening of one or more of the four components of lung tissue,
that is, airway, arterial supply, venous drainage, and parenchyma. The
abnormalities of airway, arterial supply, or both are classified as
tracheobronchopulmonary malinosculation, arterial malinosculation, and
bronchoarterial malinosculation, respectively. The classification is then
completed by describing the associated findings of venous drainage and lung
parenchyma." This classification includes all congenital lung anomalies
in which there is abnormal connection (malinosculation) and improves our
understanding of these conditions. Under this system, our case falls into the
category of bronchoarterial malinosculation. The other entities that are
included in this category are sequestration, lung cysts with aberrant systemic
supply, congenital cystic bronchiectasis and scimitar syndrome.
The proposed explanation for the anomaly that we describe is an insult that
is severe enough to disrupt both airway and pulmonary arterial development,
leading to a persistent systemic arterial supply
[1]. In the early stages of
lung development, the tips of the dividing bronchial buds are supplied by a
systemic capillary plexus derived from the primitive aorta, which regresses
with further development of lung and pulmonary artery
[1]. The timing and severity of
the insult are important in determining the morphology of the lesion. The
cause of bronchial atresia is controversial. Because the bronchial tree distal
to atresia branches normally, it has been postulated that the insult may have
occurred after completion of the process of airway development at about 16
weeks [4]. However, the
coexistence of other congenital defects that occur early in embryological
development (as in our case) supports the hypothesis that an insult occurs
during the stage of lung budding resulting in a localized abnormality followed
by normal development of the distal bronchial tree
[5]. The persistent systemic
arterial supply can be explained by the arrest of pulmonary arterial growth.
In the absence of pulmonary blood supply, the systemic vessels provide the
only support for the developing lung.
Anomalous systemic supply to the lung without sequestration, also known as
Pryce type 1 sequestration, is the rarest form of congenital anomalous
systemic arterial supply to the lung
[6]. The systemic artery can
arise from the lower thoracic aorta; upper abdominal aorta; or, rarely, the
celiac axis [7] and supplies
the otherwise normal basal segments of lower lobes. It typically affects the
left lower lobe, although it can also occur in the right lower lobe
[7]. The artery can measure up
to 1 cm in diameter and may show wall calcification and atherosclerotic change
[6]. The pulmonary arterial
supply to the affected segment may be normal or absent
[7], but the venous return is
always via the normal inferior pulmonary vein. In effect, the anomaly is a
left-to-left shunt. In a retrospective review of chest radiography and CT
findings in patients with systemic arterial supply without sequestration, Kim
et al. [6], described volume
loss with diffuse dilatation of intrapulmonary vasculature in the affected
lobe of the lung. In contrast, our case shows segmental emphysematous changes
in the left lower lobe due to air trapping in bronchial atresia. Another
unique feature in this case is the association with bronchial atresia. In
contrast to bronchopulmonary sequestration, accompanying congenital anomalies
have never previously been described in systemic arterialization without
sequestration [8].
Systemic arterial supply without sequestration may present clinically in
various ways. In infancy, it may present with a continuous chest murmur and
congestive cardiac failure due to massive left-to-left shunt
[7]. In later life, it can also
present with hemoptysis or it may remain asymptomatic, to be discovered as an
incidental finding on chest radiograph or CT scan. Treatment is recommended in
all symptomatic patients and also in asymptomatic individuals because of the
risk of hemorrhagic complications
[9]. Surgery consisting of
ligation of the anomalous vessel with or without resection of the involved
lung parenchyma is the usual treatment of choice
[8]. Endovascular treatment has
been described in a few case reports and can be a much less invasive
alternative to surgery [8,
9].
In summary, the illustrated case represents an interesting combination of
two rare anomalies—systemic arterial supply without sequestration and
congenital bronchial atresia, identified on MDCT with volume-rendered
reconstructions. Differentiation from sequestration is important and may allow
nonoperative management by embolization of the systemic feeding vessel.
References
- Clements BS, Warner JO. Pulmonary sequestration and related
congenital bronchopulmonary-vascular malformations: nomenclature and
classification based on anatomical and embryological considerations.
Thorax 1987;42(6):401
-408[Abstract/Free Full Text]
- Pryce DM. Lower accessory pulmonary artery with intralobular
sequestration of lung: a report of seven cases. J
Pathol 1946;58:457
-467[CrossRef]
- Sade RM, Clouse M, Ellis FH. The spectrum of pulmonary
sequestration. Ann Thorac Surg1974; 18:644
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- Schuster SR, Harris GB, Williams A, Kirkpatrick J, Reid L.
Bronchial atresia: a recognizable entity in the pediatric age group.
J Pediatr Surg1978; 13(6D):682
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- Williams AJ, Schuster SR. Bronchial atresia associated with a
bronchogenic cyst: evidence of early appearance of atretic segments.
Chest 1985;87(3):396
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findings in 11 patients. J Thorac Imaging2002; 17:34
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- Matzinger FR, Bhargava R, Peterson RA, Shamji FM, Perkins G.
Systemic arterial supply to the lung without sequestration: an unusual cause
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- Bruhlmann W, Weishaupt D, Goebel N, Imhof E. Therapeutic
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Eur Radiol 1998;8:355
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- Chabbert V, Doussau-Thuron S, Otal P, et al. Endovascular treatment
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Introduction
Case History
