Keywords endograft infection - TEVAR - ascending aorta - ascendobifemoral bypass - extra-anatomic
- revascularization
Introduction
The endovascular therapy became the first option for treating patients with abdominal
and thoracic aortic aneurysms, aortic dissections (Stanford Type B, BeBakey III),
intramural hematoma, and penetrating aortic ulcer (PAU).[1 ]
[2 ] In comparison to the open surgical procedures, it is associated with a lower risk
of intraoperative trauma, less mortality and morbidity, as well as shorter hospital
stay. Despite advantages, complications after endovascular aortic repair (EVAR) and
thoracic EVAR (TEVAR) require open surgical measures. Especially infections of aortic
endografts with high mortality rates are a challenge.[3 ] Endograft infections (EIs) might occur in 0.2 to 5% of the patients.[3 ]
[4 ] The constitutional symptoms are fever, malaise, thoracic and abdominal pain, weight
loss, hematochezia (aortoenteric fistula), and hemoptysis (aortoesophageal or aortobronchial
fistula).[5 ]
[6 ] Perioperative stent graft seeding, hematogenous seeding, and mechanical erosion
of the stent graft are the proposed mechanisms of EI.[5 ] Staphylococcus aureus and Streptococcus occur as the most frequently isolated bacteria from blood cultures.[1 ]
[3 ]
[5 ]
[6 ] The computed tomography angiography (CTA) and fluorodeoxyglucose positron emission
tomography are regarded as leading imaging techniques for diagnosis of EI. Despite
follow-up protocols after endovascular procedures, there are no screening strategies
to detect EI.[1 ] The treatment of EI encloses antibiotic therapy and in situ or extra-anatomic reconstructions.
Current in situ procedures include aortoaortic, aorto-bi-iliac, or aortobifemoral
bypasses and for the extra-anatomic reconstruction, axillofemoral or axillobifemoral
bypass. In addition, extra-anatomic procedures such as ascending to descending aortic
bypass and ascendoabdominal aortic bypass can be applied. The materials for reconstruction
are autologous femoral vein, cryopreserved allografts, rifampicin soaked grafts, and
prosthetic grafts.[3 ]
[4 ]
[6 ]
[7 ]
[8 ]
[9 ] In this case report, we describe the medical history of a patient with an initial
treatment of an EI after TEVAR with an uncommon use of the ascending aorta (AA) as
donor artery for the implantation of an ascendobifemoral bypass.
Case Description
A 74-year-old male patient was referred by the general practitioner to our outpatient
department with intermitted fever, progressive back pain, and recently occurring hemoptysis.
The laboratory values indicating an inflammation were elevated. One month ago, he
was diagnosed with a ruptured PAU and subsequently treated with TEVAR. Despite a long-term
oral antibiotic therapy, the clinical symptoms did not ameliorate. We hospitalized
the patient and started intravenous antibiotic therapy immediately. Blood cultures
revealed the presence of S. aureus . The CTA showed gas collections around the aortic stent graft what confirmed the
EI ([Fig. 1 ]). The infection expanded retrograde right above the celiac trunk up to the aortic
arch including the left-sided common carotid artery (CCA). By lacking effect after
the antibiotic therapy, we discussed to implant an extra-anatomic ascendobifemoral
bypass and performed the procedure after counseling with the patient. We intended
to keep both prosthesis limbs retrosternal through the mediastinum and intra-abdominal
direct below the abdominal wall. On account of the necessary sternotomy with clamping
of the AA, the cooperation with cardiac surgeons was necessary. The whole surgery
was divided in two stages. In the first stage, after a minimal sternotomy, the AA
was prepared and clamped tangentially without the assistance of the heart lung machine.
For the safety of the cerebral and brachial perfusion, a bypass (Dacron graft 14 × 7 mm,
Vascutek) between the AA and the left-sided CCA and subclavian artery was performed
([Fig. 2 ]). Following this procedure, the aortic arch was interrupted distally of the brachiocephalic
trunk as a first step of the complete resection of the infected aortic stent graft.
Subsequently, the ascendobifemoral bypass was implanted. After the proximal end-to-side
anastomosis to the AA (Dacron graft 20 × 10 cm, Vascutek), both prosthesis limbs were
laid retrosternal and intra-abdominal underneath the abdominal wall to the inguinal
region. Following this, an anastomosis to the both-sided common femoral arteries was
performed ([Fig. 3 ]). In the second stage, following a left-sided thoracotomy, we ligate the thoracic
abdominal aorta proximal of the celiac trunk and explanted the infected stent graft
entirely ([Fig. 2 ]). During the first postoperative week at the intensive care unit, the renal and
mesenteric system showed no dysfunctions. The inflammation parameters decreased continuously.
Neurological symptoms did not appear. For prophylaxis of embolic events, we established
a therapy consisting of aspirin and low-molecular-weight heparin. Over the subsequent
weeks, the patient developed several comorbidities such as renal insufficiency with
the need for dialysis, spondylodiscitis, cholangitis, and respiratory insufficiency
with prolonged intubation with resulting pneumonia. Two months after surgery, the
patient died due to a sepsis.
Fig. 1 Computed tomography angiography images with gas collections surrounding the thoracic
stent graft (yellow arrows).
Fig. 2 Three-dimensional computed tomography angiography images of the whole reconstruction
with (A ) the aortocarotidal–subclavian bypass (red arrow) and prosthesis limbs leading to
the femoral arteries (yellow arrows) and (B ) the explanted aorta section.
Fig. 3 Computed tomography angiography images with the (A ) retrosternal and (B ) abdominal.
Discussion
According to the international data, EI is a rare complication after EVAR and/or TEVAR.
However, in both cases, treatments remain challenging. The origin of EI is not yet
completely cleared. Especially persistent endoleaks are assumed as the most important
origin of thrombus seeding, which leads to an increased likelihood of EI.[5 ] Animal experiments show that a relevant preventing factor for EI is the formation
of an endothelial covering during the neointimal healing process.[5 ] The use of antibiotics for avoiding hematogenous bacterial graft seeding usually
occurs preoperatively and is continued postoperatively often for a period of 4 or
6 months. As EI mostly become obvious during the first 3 months after surgery, a continuous
antibiotic therapy is recommended for 12 months or even lifelong.[5 ]
[6 ] Patients with good response to antibiotics, a low expansion of the infection, and
high perioperative risk can be treated in the long term conservatively. In the presence
of extended local infections, inefficient antibiotic respond, and an aortoesophageal
fistula, a total endograft excision with surgical reconstruction is recommended.[4 ]
[6 ]
[8 ] In particular, the infection of the thoracic aorta shows a high mortality, which
is caused by the complex reconstruction procedures.[3 ] Reviewing the literature mortality rates for nonexcisional therapy of infected aortic
endografts range from 33 to 70%[3 ] and for surgical procedures from 51 to 84% after 5 years of follow-up.[1 ]
[3 ]
[4 ]
[8 ] In our case, the pronounced cranial and caudal infections of the aorta including
the left-sided CCA and subclavian artery as well as the proximity to the celiac trunk
lead us to the decision for an extra-anatomic reconstruction. Guided by the widely
accepted consensus for treatment with a completely explantation of the infected aortic
area,[1 ]
[6 ]
[7 ] we decided for an extra-anatomic reconstruction using the AA as a donor artery for
revascularization. With the performance of the ascendobifemoral bypass instead of
ascendoabdominal aortic bypass, we intended to avoid, in particular, a manipulation
within the infected abdominal aortic area. In addition, we intended to keep a short
duration and avoid a two-cavity procedure. Complications such as bypass flow reduction
caused by stenosis of the diaphragm section ([Fig. 3 ]) causing legs ischemia or cerebral embolization by manipulating at the aortic arch
did not appear. Our case indicated performing the procedure described earlier is safe,
and complications such as brain embolization or other ischemic events could be avoided.
To our knowledge, the literature shows no similar case for this kind of surgical procedure;
wherefore, long-term outcome for the extra-anatomic ascendobifemoral bypass is not
known. To prevent EI in the future, there is a need for more studies concerning the
exact postoperative application period of antibiotics and the development of screening
strategies for early EI detection.
