Keywords
aortic arch false aneurysm - pseudoaneurysm - temporary bypass
Introduction
Damage to the aorta as result of blunt chest trauma is a rare and dangerous condition
with a high mortality rate (80–90%) due to massive bleeding. However, in some patients,
despite the rupture of the thoracic aortic wall, mediastinal tissues “restrain” the
hematoma, preventing the development of fatal bleeding. Subsequently, this leads to
the formation of a false aneurysm. According to Parmley et al,[1] the most frequent site of aortic rupture in such injuries is the zone of its isthmus.
This location of injury at the isthmus has been attributed to embryogenesis of the
aorta and anatomical features.[1] The localization of the rupture in the region of the aortic arch, as in our case,
is an extremely rare observation.
Case Presentation
A 44-year-old male patient was admitted to our Vascular Surgery Department.
In 2001, the patient was in a traffic accident, resulting in a blunt injury to the
chest and pelvis. This, presumably, was the mechanism of development of an aneurysm
of the aortic arch.
In 2012, on the plane X-ray of the chest, an abnormal mass lesion was found, but computed
tomographic (CT) verification was not performed due to unknown reason.
In 2014, the patient was hospitalized in our department when we confirmed the diagnosis
of the aortic arch pseudoaneurysm ([Fig. 1]). CT imaging identified a giant pseudoaneurysm with maximum size 136 × 72 mm. The
size of posterior aortic arch wall defect was 28 mm. There were no signs of aortic
dissection.
Fig. 1 Preoperative CT aortography of pseudoaneurysm of the aortic arch in the posterior
mediastinum.
We performed an operation—the elimination of the aortic arch pseudoaneurysm and posterior
wall tear and false aneurysm in the mediastinum without the use of cardiopulmonary
bypass.
The position of the patient was on hs back with his left hand fixed above the head.
Under total anesthesia, through the L-shaped median sternotomy and left 5th intercostal
thoracotomy, we identified and extracted the ascending aorta, aortic arch, left common
carotid and subclavian arteries and mid part of descending aorta ([Fig. 2]).
Fig. 2 L-shaped median sternotomy with a left thoracostomy in the fifth intercostal space:
(a) schematic, (b) intraoperative picture of the approach, (c) distal anastomosis between temporary shunt and descending thoracic aorta, (d) proximal anastomosis between temporary shunt and descending thoracic aorta.
The brachiocephalic trunk was unable to mobilize because it was intimately fused with
the anterior wall of the false aneurysm. Therefore, the right subclavian artery was
controlled. A temporary bypass (TB) shunt of 20 mm between the ascending and descending
aorta was created. In addition, from this bypass an anastomosis with a bifurcation
prosthesis for temporary blood supply to the brachiocephalic trunk and left common
carotid artery was formed. The first branch of the bifurcated bypass was anastomosed
to the right subclavian artery, and the second connected through cannulation to the
left carotid artery. The bloodstream was allowed to run through all temporary shunts.
The ascending aorta was clamped distal to the shunt, and the descending aorta was
clamped proximal to the shunts. Single clamps were placed on the brachiocephalic trunk,
left carotid, and left subclavian arteries. Then, a longitudinal aortotomy was made
on the front wall of the aortic arch. On the back, the aortic wall was detected, with
the defect (with smooth edges, 35 × 20 mm) leading into the cavity of the giant pseudoaneurysm,
which was partially filled with old thrombotic material. The posterior aortic wall
defect was closed with a Dacron patch. The anterior aortic wall was restored by closing
the incision in the aortic wall, with Teflon felt reinforcement. Blood flow was sequentially
restored in the aorta and its branches ([Fig. 3]).
Fig. 3 Operation method scheme and intraoperative pictures: (a) operation schematic, (b) aortic lumen with aneurysm cavity, (c) aortic wall restoration, (d) restoring of the blood flow and the temporary shunt deleting. 1, temporary shunt;
2, aortic arch restoration.
During the entire operation, blood pressure on the right brachial and femoral artery
did not flow below 85 and 90 mm Hg. The duration of operation was 480 minutes. The
duration of anesthesia was 680 minutes.
Total blood loss was 1,500 mL, with approximately 700 mL from aneurysm cavity. There
were no complications after surgery.
On the first day after operation, a right-sided pneumothorax was diagnosed, which
was treated with active drainage. On the second day, the patient was extubated.
An additional drainage to the left pleural cavity was implanted on the fifth day due
to persistent left-sided limited pneumothorax. The patient was discharged in good
condition on the 19th day after the operation.
CT scan at 8 months has shown a persistently closed defect ([Fig. 4]). The size of aneurysm became two times less during 8 months of observation.
Fig. 4 Postoperative CT of the operation zone 15 days after surgery (a, b). Aortic arch aneurysm is isolated from the bloodstream; 8-month follow-up (c, d).
Discussion
Currently, there are two treatment methods for surgery of aortic arch aneurysms. Most
often, an aneurysm resection is made with an aortic prosthesis performed using artificial
circulation and circulatory arrest with antegrade cerebral perfusion. The second method
is a hybrid operation on the aortic arch with complete debranching and implantation
of stent graft modules.[2]
[3] The method of treatment applied by our team for this giant false aneurysm of the
aortic arch made it possible to perform this operation in a department without cardiac
surgical or endovascular equipment and teams. The use of a TB between the ascending
and descending aorta accomplishes an adequate unloading of the left chambers of the
heart during the thoracic aorta clamping and provides enough blood flow and pressure
to the lower extremities, abdominal aorta, and visceral arteries. Temporary debranching
of the brachiocephalic arteries maintains adequate perfusion of the brain.
