Keywords
aneurysm - cardiovascular surgery - thoracic surgery
Introduction
Infective systemic complications in patients under continuing immunosuppressive therapy
are common, but mycotic arterial aneurysms are very rare.[1] Vascular reconstruction is usually performed with alloplastic material according
to the site and size of the lesion. In native and prosthetic vascular infection after
aortic surgery and intervention, self-made pericardial tube-graft have proven to be
an attractive treatment option to overcome the issue of reinfection of alloplastic
vascular material.[2] However, there are no reports using this strategy at the level of the supra-aortic
branches.
Case Report
A 63-year-old female with a history of kidney transplantation was admitted to a referring
hospital due to gastroenteritis symptoms, dehydration, urinary tract infection, and
fever. Initial X-ray showed a right superior mediastinal mass, which was interpreted
as a pulmonary or mediastinal abscess, respectively. The patient had been initially
treated with wide spectrum antibiotic therapy for a week, but the symptoms and fever
persisted. Further diagnostics now using a computed tomography (CT) angiography showed
a 3.5 × 2.9 cm mycotic aneurysm of the intrathoracic right subclavian artery (RSA)
beginning 2 cm distal to the offspring from the brachiocephalic trunk ending at the
level of the thoracic outlet uncompressing the offspring of the right vertebral artery
and the right internal mammary artery ([Fig. 1]). In addition, paravertebral and posterior mediastinal abscesses were seen. Furthermore,
venous obstruction due to compression of the venous confluence was observed. Consecutively,
the patient was transferred to our hospital, and emergency surgery was performed.
Fig. 1 Pre-operative CT angiography showing a partially thrombosed aneurysm (A) of the right
subclavian artery (S) with air lucencies and severe inflammatory changes. Also, a
thrombus (arrow) is seen in the subclavian artery, directly distal to the aneurysm.
Edematous subcutaneous tissue of the right chest wall, right axial, and right neck
root as well as right shoulder muscles. CT, computed tomography.
Initially, the extrathoracic RSA as well as the right common carotid (RCCA) artery
was circumferentially dissected and encircled with silastic tapes for distal bleeding
control. Then, a median sternotomy was performed, and the central brachiocephalic
trunk was secured. Afterward, the RSA was dissected centrally and clamped after systemic
heparinization with 100 IU/kg bodyweight. In addition, the extrathoracic RSA and the
RCCA were clamped. Then, the abscess formation was opened. Swabs were taken. The posterior
wall of the intrathoracic RSA was completely destructed by the infective process,
and discontinuity at the level of the right vertebral artery offspring could be observed
([Fig. 2]). Remaining back bleeding from the RSA was controlled via a Fogarty catheter. After
radical local debridement, orthotopic repair was performed with a self-made pericardial
tube graft from the brachiocephalic bifurcation to the thoracic outlet. For this purpose,
a 14 × 8 cm bovine pericardial patch (LeMaitre XenoSure Biologic Patch) was sized
down to 8 × 4.8 cm and was sewn to form a tubular graft with a diameter of 1.5 cm
and a length of 8 cm. The continuing suture row was sewn with 4–0 Prolene (polypropylene)
suture (Ethicon, Summerville, New Jersey, United States), and a knot was made at 4
cm to allow the use of a shorter segment if necessary.[2] The vertebral artery was not involved and was maintained well.
Fig. 2 Intraoperative situs before opening of the abscess formation (A). Intraoperative situs after neopericardial tube graft insertion (B).
The paravertebral and posterior mediastinal abscess was drained via opening of the
right pleural cavity. Afterward, the wound was closed in layers. The postoperative
course was uneventful. Microbiology revealed Escherichia coli as underlying bacterium. An intravenous targeted antibiotic had been continued for
2 weeks. Completion CT scan showed regular arterial perfusion of the right upper extremity
and a regular situs without any remaining signs of remaining or recurring infection
([Fig. 3]). The regular control after 1 and 5 months with Duplex sonography showed good patency
of the graft.
Fig. 3 Reconstructed postoperative CT angiography images showing the reconstructed right
subclavian artery with regression of the air lucencies and patent subclavian artery
with good distal run off. Arrow: proximal anastomosis, Arrow head: distal anastomosis.
CT, computed tomography.
Discussion
Mycotic arterial aneurysms in patients either under chronic immunosuppression or in
an immunocompromised state due to infection, such as human immunodeficiency virus
(HIV) are very rare.[1]
[3] However, mycotic aneurysms of the subclavian arteries in both groups at risk have
been reported. In a group of patients with HIV infection, a large series reporting
40 arterial aneurysms, merely 2 were located at the level of the subclavian arteries.[3]
Symptoms are usually related to size, location, and affection of adjacent structures.
Intrathoracic subclavian artery aneurysms may cause dysphagia, upper limb edema, and
Horner's syndrome, whereas extrathoracic subclavian artery aneurysms may compress
the cervical plexus causing dysesthesia or even motoric deficits.[4] However, symptoms are unspecific, and suspicion is needed to establish the diagnosis.
In case of suspicion, liberal uses of imaging modalities, such as CT angiography,
are recommended.
Several treatment options, besides germ-oriented antibiotic therapy are available.
Endovascular therapy has been used. However, this approach requires insertion of alloplastic
vascular material and may be seen as a bridge to definitive therapy as the likelihood
of additional infection of the implanted covered stent is to be foreseen.[5] Saphenous vein graft interposition is an attractive option. However, this technique
requires a similar diameter between the native artery and the venous interposition,
which is not always given.[6] Simple ligation of the native vessel has been used. However, collateral flow should
be sufficient to provide adequate flow to the respective upper extremity. Finally,
claudication on exertion or even limb ischemia should be considered as an adverse
effect while using this approach.[4]
Using alloplastical material for classical surgical reconstruction has been successfully
reported. However, the remaining risk of recurring infection remains, and antibiotic
therapy has to be extensively continued.
Self-made pericardial tube grafts are readily available, can be tailored to the individual
size needed, and have been reported to be a very durable solution in case of native
and prosthetic aortic infection.[2] We sought to transfer this concept in this emergency scenario anticipating similar
favorable outcome in the supra-aortic position. In addition, site-harvesting complications,
in particular, in patients under immunosuppression, can be avoided.
In brief, using a self-made readily available pericardial neo-tube enlarges the armamentarium
of handling complex infective surgical scenarios and presents a smart alternative
to alloplastic vascular reconstruction.
