Discussion
For the aortic arch aneurysm with concurrent PAU in the descending
aorta, there are many approaches, including TAR with FET, type I hybrid
arch repair (arch debranching in native aorta zone 0 and TEVAR) and type
II hybrid arch repair (arch debranching in Dacron zone 0 after ascending
aorta replacement and TEVAR) (1), TEVAR with chimney technique, and
hemiarch and descending aorta replacement via thoracotomy(2). In this
case, the diameter of ascending aorta was 41 mm. Considering the
ascending aorta more than 40mm is associated with a high risk of
retrograde ascending aortic dissection after TEVAR(3), we abandoned type
I hybrid arch repair and TEVAR with chimney technique. And if we
performed type II hybrid arch repair, at least two TEVAR stent grafts
were needed, and the medical expenses were expensive for the patient.
Moreover, hemiarch and descending aorta replacement via thoracotomy
shows worse outcomes when comparing with TAR(2). Therefore, we performed
type III arch repair for this patient.
In this case, a FET stent with a length of 120mm was selected to cover
the PAU, because the distance from the PAU to the left subclavian artery
was about 100mm. But there may exist little deviation when measuring the
distance on CT scan. And the tip of the FET stent is very sharp.
Therefore, we analyzed that the tip of the FET stent was possibly at the
same level with the PAU after deployment, and the tip may have been
inserted into the PAU and caused iatrogenic aortic dissection. The
Microport FET system was routinely used for TAR at our center. The
delivery system enables direct insertion without a guidewire. And the
FET stent had been correctly deployed in all cases. It was a rare case
with incorrect FET deployment.
From this case, we could conclude that attention should be taken to
avoid incorrect deployment of FET. We had also summarized some points to
prevent this complication, especially in patients with a large tear or
ulcer lesion in the proximal descending aorta. Firstly, the FET stent
could be deployed with a guidewire under direct vision. The guidewire
could also be retrogradely placed through femoral artery. Secondly,
early detection of iatrogenic aortic dissection was very important. The
radial artery pressure and the femoral artery or the dorsalis pedis
pressure should be closely monitored intraoperatively to identify aortic
dissection. And serum lactic acid should also be closely monitored to
detect visceral malperfusion. Thirdly, the distance from the left
subclavian artery to the primary tear or ulcer lesion in the descending
aorta should be measured carefully on CT scan. If the distance was very
close to the length of the commercially available FET stent (100mm,
120mm), we could adopt type II hybrid arch repair. Because retrograde
deployment of TEVAR stent through a guidewire under X-ray is very safe.
Moreover, distal arch and descending aorta replacement via thoracotomy
could also be adopted in this situation.
Once iatrogenic aortic dissection had happened, some salvage procedures
should be performed. If the aortic dissection was detected early, we
could remove the suture lines and take out the FET stent under
hypothermic circulatory arrest, then re-deploy the FET stent into the
true lumen of the descending aorta. Besides, endovascular aortic
fenestration and additional stent deployment would be the suitable
option. But the fenestration technique was very difficult and carried
high risks(4). And open fenestration could also be adopted when the
other strategies were not available(5).
Conflict of interest: none declared.
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Figure 1: (A)(B) CT scan after admission; (C) CT scan 10 days later.
Arrows represented the PAU of the descending aorta, and asterisk
represented the aortic arch aneurysm.
Figure 2: (A) Aortography showed that the narrow thoracic aorta
resembling a thin line. (B) Aortography showed the thoracoabdominal
aorta, bilateral intercostal arteries and lumbar arteries, while the
celiac axis, superior mesenteric artery and renal arteries disappeared.
(C) Endovascular thoracoabdominal aortic fenestration was performed to
connect the true lumen and the false lumen. (D) Stent graft was
retrogradely deployed to the descending aorta.