AJR 2000; 174:1341-1343
© American Roentgen Ray Society
Lung Torsion After Lung Transplantation
Evaluation with Helical CT
R. C. Gilkeson1,
Paul Lange2 and
Thomas J. Kirby3
1
Department of Radiology, University Hospitals of Cleveland, Case Western
Reserve University School of Medicine, 11100 Euclid Ave., Cleveland, OH
44106.
2
Department of Medicine, University Hospitals of Cleveland, Case Western
Reserve University School of Medicine, Cleveland, OH 44106.
3
Division of Cardiothoracic Surgery, University Hospitals of Cleveland, Case
Western Reserve University School of Medicine, Cleveland, OH 44106.
Received July 16, 1999;
accepted after revision October 7, 1999.
Address correspondence to R. C. Gilkeson.
Case Report
A 34-year-old male sandblaster with end-stage silicosis was referred to our
institution for lung transplantation evaluation. Preoperative radiographs and
high-resolution CT were consistent with end-stage silicosis. Pulmonary
function tests revealed a forced expiratory volume of 0.67 1 (18% predicted)
and a predicted diffusion capacity of 30%. The patient underwent an
uncomplicated single right lung transplant in which the donor allograft was
significantly smaller than the recipient's right hemithorax. The patient was
extubated on the first day after transplantation. On the third day, a chest
radiograph revealed right basilar consolidation and a right basilar
pneumothorax. A transesophageal echogram, obtained to evaluate for pulmonary
venous infarction, revealed turbulent flow in the right inferior pulmonary
vein.
Helical CT was requested to evaluate the venous anastomosis. CT was
performed from the aortic arch to the diaphragm with 140 ml of contrast
material, a 3-mm collimation, and a 1-mm reconstruction interval. Volumetric
reconstructions were performed on a Picker Voxel workstation (Picker
International, Cleveland, OH). The tracheobronchial tree showed mild narrowing
at the right bronchial anastomosis. We noted a 90-120° counterclockwise
rotation of the right middle lobe bronchus, with marked narrowing of the right
lower lobe orifice and an abnormal bronchial branching pattern
(Fig. 1A). Helical CT with
mediastinal window settings revealed a reversal of the normal arterial and
venous relationship in the right lower lobe, with narrowing of the inferior
pulmonary vein (Fig. 1B).
Parenchymal windows revealed interlobular septal thickening in the
posterolaterally displaced right middle lobe
(Fig. 1A), with peripheral
opacity in the right middle and lower lobes consistent with venous congestion
and infarction (Fig. 1C).
Sagittal multiplanar reconstructions of the transplanted lung revealed
abnormal orientation of the right major fissure
(Fig. 1D). The constellation of
findings was consistent with those of partial torsion of the transplanted
lung.
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Fig. 1A. —34-year-old man who underwent lung transplantation for silicosis and
developed right lower lobe consolidation 3 days later. Axial helical CT scan
obtained at level of bronchus intermedius reveals posterolateral displacement
of right middle lobe bronchus (black arrow). Note narrowing of lower
lobe bronchus (arrowhead). Also note prominent interlobular septal
thickening in displaced right middle lobe (white arrow).
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Fig. 1B. —34-year-old man who underwent lung transplantation for silicosis and
developed right lower lobe consolidation 3 days later. Axial helical CT scan
with mediastinal window settings shows abnormal transposition of lower lobe
pulmonary artery (long arrow) relative to narrowed inferior pulmonary
vein (short arrow).
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Fig. 1C. —34-year-old man who underwent lung transplantation for silicosis and
developed right lower lobe consolidation 3 days later. Axial helical CT scan
inferior to A shows posterolateral displacement of right middle lobe
(M). Consolidated right lower lobe (L) is anteromedially displaced. Posterior
consolidation (arrow) is probably caused by venous congestion and
infarction.
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Fig. 1D. —34-year-old man who underwent lung transplantation for silicosis and
developed right lower lobe consolidation 3 days later. Sagittal multiplanar
reconstruction shows abnormally reversed orientation of right major fissure
(straight arrows). Note inferiorly displaced and congested superior
segment of right lower lobe (curved arrow). A = anterior, P =
posterior.
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After radiography, a bronchoscopic image was obtained to confirm CT
findings. The image revealed the markedly distorted orientation of the right
middle and lower lobe orifices: the right middle lobe was posterolaterally
displaced and the right lower lobe orifice was narrowed, erythematous, and
inferiorly displaced (Fig. 1E).
These findings were consistent with the incomplete torsion of the right middle
and lower lobes. MR angiography was performed and confirmed continued patency
of the pulmonary veins. Because of the patient's benign clinical course,
surgical correction was unnecessary. The patient remained clinically stable
for 6 months after surgery, and repeat bronchoscopies have revealed continued
incomplete torsion of the transplanted right lung.
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Fig. 1E. —34-year-old man who underwent lung transplantation for silicosis and
developed right lower lobe consolidation 3 days later. Bronchoscopic image
(oriented to look down from head of patient) obtained at level of bronchus
intermedius shows abnormal orientation of right middle lobe bronchus (M)
(long arrow). Note expected location of right middle lobe orifice
(short arrow). Lower lobe bronchus (L) is narrowed and erythematous.
Bronchoscopic orientation: a = anterior, p = posterior, m = medial, l =
lateral.
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Discussion
Lung torsion is a rare entity, with fewer than 60 reported cases. Although
most patients have involved thoracic trauma, reports of lung torsion
complicating pneumonia, Heller's esophagomyotomy
[1], and percutaneous lung
biopsy exist. A survey of thoracic surgeons revealed that most patients
develop lung torsion after lobectomy because the surgical division of the
pulmonary ligament encourages increased mobility of the remaining lobes
[2]. Patients with complete
fissures are at particularly high risk, and many surgeons affix the right
middle lobe to the remaining lobe to prevent postoperative torsion
[2].
Lung torsion is unusual in the native lung and exceedingly rare in lung
transplants, with only one case reported in the literature
[3]. In lung transplantation,
the risk of lung torsion is theoretically higher because of the division of
the pulmonary ligament of the donor lung. The surgical complexity of lung
transplantation and the number of anastomoses may also predispose
transplantation patients to lung torsion. In our patient, the size differences
of the donor lung and the patient's hemithorax were additional factors
contributing to torsion.
The clinical sequelae of lung torsion compromise the three pulmonary
vascular systems [4]. It is
difficult to experimentally cause lung infarction with isolated obstruction of
the pulmonary arterial supply because an intact bronchial artery supply is
usually protective. As the tracheobronchial tree is twisted in lung torsion,
compromise of the pulmonary arterial, venous, and bronchial circulation
develops. In patients with complete torsion, the onset of pulmonary gangrene
is rapid [5], and immediate
surgery is required. As in our patient, various studies report patients with
partial torsion and angiography findings that reveal sluggish but intact
arterial and venous flow in the affected lung. In our patient, the original
findings of lung consolidation probably reflect venous congestion resulting
from partial lung torsion and venous narrowing, as seen on helical CT scans.
The patient's benign clinical course reflects the incomplete torsion, with
maintenance of adequate blood flow to the affected lung.
The clinical presentation of lung torsion is usually acute, yet the rarity
of this condition commonly results in a significant delay in diagnosis.
Patients present with chest pain, hemoptysis, bronchorrhea, or persistent air
leaks. Undiagnosed complete lung torsion often leads to fulminant pulmonary
gangrene and death, and if the condition is not recognized in the first
several hours, surgical intervention may be useless. In the largest study of
partial lung torsion, patients often presented with suspected pneumonia or
lobar collapse [6]. The
clinical diagnosis was frequently originally made at bronchoscopy, when
distortion or occlusion of the affected airway was discovered.
Imaging plays an important role in the diagnosis of lung torsion. The
torsive lobe or lung often presents as a consolidated or collapsed lobe. An
unusual change in position of this collapsed lobe should suggest possible
torsion. Felson [7] describes
hilar displacement and distortion as an important feature in lung torsion. CT
findings include bronchial obstruction or distortion and abnormal arterial and
venous relationships in the torsive lung
[8]. Several case reports
describe the serendipitous diagnosis of lung torsion during pulmonary
angiography when the distorted arterial and venous anatomy showed displaced
and compromised or sluggish flow in the affected lobes
[9].
To our knowledge, only one other study reports a patient with lung torsion
after lung transplantation. In that study, the patient's torsion involved an
isolated left upper lobe torsion after bilateral lung transplantation
[3]. The diagnosis was made
after CT scanning revealed a consolidated abnormally positioned left upper
lobe with associated left mainstem bronchus obstruction
[3]. In our patient, the use of
helical CT scanning allowed the prospective diagnosis of a confusing clinical
presentation. Despite the radiographic and bronchoscopic appearance of lung
torsion, the documentation of an intact arterial and venous blood supply
allowed the noninvasive clinical observation of our patient, who continues to
do well 6 months after his lung transplantation.
Acknowledgments
We thank Virginia Wormald for her expert secretarial assistance and Bonnie
Hami for her expert editorial advice.
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