https://orcid.org/0000-0001-8731-7374
Abstract
Emergency repair of type II thoracoabdominal aortic aneurysms is burdened by high perioperative morbidity and mortality. We report the case of a symptomatic type II post-dissection thoracoabdominal aortic aneurysm that was treated using a hybrid technique. The repair was carried out in 2 stages. In the first stage, we deployed 2 imbricated stent grafts in the descending thoracic aorta. A left carotid-to-left subclavian artery bypass was pre-emptively performed to obtain a proper proximal landing zone and as part of the manoeuvres to protect the spinal cord. The endovascular first stage was effective in obtaining proximal sealing but, as expected, it did not prevent distal reperfusion of the aneurysmatic false lumen. A few hours later, we moved on to the second stage in which we repaired the aneurysmal distal thoracic and abdominal aortic segment by means of a multibranched synthetic graft. The repair was carried out through a left thoracophreno-laparotomy in the seventh intercostal space. A left passive arterial bypass and selective cold renal and warm visceral perfusion were adopted to provide organ protection. Technical success was achieved and confirmed radiologically. The patient experienced mild postoperative paraplegia, which almost completely regressed after a neuromotor rehabilitation program.
INTRODUCTION
Open repair of a type 2 thoraco-abdominal aortic aneurysm(TAAA) is burdened by high mortality and morbidity.
Fenestrated and branched grafts allow for an endovascular repair, with significant reduction of the perioperative risk [1].
Off-the-shelf devices are ideal in urgent cases, when it is impossible to wait for the production of a custom-made graft, but they might not fit all patients’ anatomies [2].
Chronic type B aortic dissections with aneurysmal degeneration often show anatomical features that are unfavourable for endovascular solutions. Surgical repair can represent the optimal choice [3].
We adopted a hybrid approach as a novel alternative solution in an urgent setting for the treatment of a symptomatic post-dissection type II TAAA.
CASE REPORT
A 73-year-old man with polyvasculopathy and diabetes presented to our hospital with left thoracic and lumbar pain. Ten years before, he was treated conservatively for acute type B aortic dissections. Urgent computed tomography angiography (CTA) demonstrated aneurysmatic degeneration (Fig. 1A), with a maximum aortic diameter of 12 cm in the descending thoracic aorta, compression of the true lumen (TL) and significant dilation of the false lumen (FL). The dissection extended from the isthmus to the left common iliac artery. The coeliac trunk (CT) originated from the FL and the superior mesenteric artery, and the right renal artery originated from the TL, whereas the dissection extended into the left renal artery.
(A) Preoperative computed tomography angiography 3-dimensional rendering showing the extent of the type II post-dissection thoraco-abdominal aortic aneurysm. Maximum diameter of the lesion was located below the isthmus (12 cm). The diameter of the aorta was 62 mm above the diaphragm, 48 mm at the para-visceral level, 40 mm at the para-renal level, 40 mm below the renal arteries and 24 mm at the aortic bifurcation. A suitable endovascular proximal landing zone was present below the origin of the left carotid artery (diameter 30 mm, length 26 mm). (B) First stage (endovascular): angiography after the deployment of the first stent graft demonstrates adequate proximal sealing and patency of the left carotid-to-left subclavian artery bypass. (C) Computed tomography angiography performed after the endovascular stage. Distal reperfusion of the false lumen sustained by tears in the abdominal aorta is noticeable in this reconstruction. By contrast, the perfusion of the false lumen appears to be significantly reduced thanks to an effective proximal sealing of the stent graft.
To minimize the perioperative risk in a frail patient, we opted for an urgent hybrid approach with thoracic endovascular repair and open surgical abdominal reconstruction.
First stage (night of admission):
preventive left carotid to left subclavian artery bypass → in order to obtain a proper proximal landing zone,
deployment of 2 imbricated Gore Conformable C-TAG stent grafts (TGM343420E+TGM343415E) (W. L. Gore, Newark, DE, USA) in the TL of the thoracic aorta. Aortic coverage: from below the left carotid artery to 3 to 4 cm above the CT (Fig. 1B).
CTA performed after the first stage confirmed the absence of type 1A endokeak and the expected distal reperfusion of the FL (Fig. 1C).
Second stage (the next morning):
patient placed in a modified right lateral decubitus position,
surgical exposure and cannulation of the left axillary artery and the left femoral artery in order to set up a passive temporary arterial shunt,
connection of an accessory line to a side hole exit port of the femoral cannula, intended for selective warm visceral perfusion,
left thoracophreno-laparotomy in the seventh intercostal space, providing exposure of the thoraco-abdominal aorta,
cross-clamping of the distal thoracic aorta together with the aortic stent graft deployed in its TL,
distal aortic clamping above the CT, allowing for distal reperfusion through the passive shunt,
longitudinal aortotomy between the clamps and visualization of the distal segment of the thoracic stent graft (Fig. 2A),
end-to-end anastomosis with a pledgeted mattress suture between the stent graft and a prefabricated multibranched Dacron graft,
sequential aortic cross-clamping and anastomosis between the branches of the graft and the visceral and renal arteries,
selective warm perfusion of the superior mesenteric artery through the accessory line of the shunt and renal protection through perfusion of each renal artery with a 200 ml bolus of 4°C Custodiol,
tailoring of the pararenal flap under direct visualization, and
distal end-to-end anastomosis between the graft and the infrarenal aorta (Fig. 2B).
(A) Longitudinal aortotomy after aortic cross-clamping allows for direct visualization of the distal segment of the thoracic stent graft. (B) Final result after surgical repair showing the interposition of the multibranched synthetic graft between the distal edge of the thoracic aortic stent graft and the distal infrarenal aorta. Anatomical reconstruction of the visceral and renal arteries was performed by anastomosing the collateral branches of the graft to the target vessels with a running 6/0 polypropylene suture. (C) Monitoring with computed tomography angiography demonstrates the absence of thoracic false lumen reperfusion by the contrast medium, regular patency of the visceral and renal branches and no perianastomotic defects.
Specific considerations:
preservation of the LSA during the first stage allows for
reduction of the risk of spinal cord ischaemia and
utilization of the left axillary artery as donor for the distal perfusion during the second stage,
a left heart bypass is a possible alternative, especially with regard to better haemodynamic modulation during the aortic cross-clamping; we opted for a passive shunt in order to reduce systemic heparinization and the amount of bleeding,
cannulation of the left axillary artery appeared much easier than cannulation of the left atrium, given the bulk of the aneurysmal descending aorta,
visceral debranching + coverage of the thoraco-abdominal aorta with a ‘full metal jacket’ technique represents a possible alternative that allows avoidance of the surgical exposure of the thoracic aorta; however, it is burdened by a mortality rate similar to that of standard open repair; concern is mainly represented by the risk of occlusion of the visceral branches, and
incorporation of the aortic wall in the anastomosis between the stent graft and the multibranched graft is preferrable to prevent bleeding in case of an endoleak. This procedure was not entirely possible because of the poor consistency of the aortic wall, but the result was not compromised because no residual leak from the thoracic aorta was present.
Postoperative mild paraparesis was noted, which only partially resolved after drainage of cerebrospinal fluid. Extubation was possible 48 h after the operation. CTA at 6 days demonstrated satisfying technical success (Fig. 2C). The patient underwent neuromotor rehabilitation, which led to significant improvement and only a residual right hip flexion deficit.
DISCUSSION
The extent of the aortic open repair is correlated with the mortality and complication rates, which are higher for types I and II TAAAs. Our hybrid staged approach has already been proposed as an additional valid option [4, 5]. In elective cases, it can reduce the risk of spinal cord ischaemia thanks to the adaptation of the spinal collateral circulation between the stages. We think that this strategy might also be advantageous in an urgent setting, even though the 2 stages are performed close together in time. It allows us to perform a more distal thoracotomy and to avoid manipulation of the aortic arch. Together with sequential cross-clamping and distal reperfusion, it eliminates the need for cardiocirculatory arrest and deep hypothermia. Less extensive surgical exposure through a lower thoracotomy reduces blood loss and postoperative pain and allows for ventilation of the left lung throughout the procedure, leading to a decreased risk of respiratory complications.
Admittedly, with a hybrid procedure, we do not replace the dissected thoracic aorta, but our only goal is to obtain thrombosis of the FL. Thereby, the future risk of FL reperfusion by a type IA or II endoleak persists.
CONCLUSION
A staged hybrid repair of extensive TAAAs appears to be a valid option. Concern about the possibility of thoracic FL reperfusion represents the pitfall of this approach.
FUNDING
No funding was received for the preparation of this manuscript.
Conflict of interest: none declared.
DATA AVAILABILITY
The data underlying this article will be shared on reasonable request to the corresponding author.
ETHICAL STATEMENT
Patient informed consent was obtained.
Reviewer information
European Journal of Cardio-Thoracic Surgery thanks Jürg Schmidli, Santi Trimarchi, Gabriele Piffaretti and the other, anonymous reviewers for their contributions to the peer review process of this article.
