Collapsed endograft and lower limb ischemia from type B dissection repaired with thoracic endovascular aortic graft and iliac stenting: A case report and review of the literature

The collapse of an abdominal aortic endograft is a rare event. We present the case of a 60-year-old man with an abdominal endograft who came to the emergency department with chest, back, abdominal, and lower extremity pain in addition to a cool left foot. On imaging, he was found to have a type B aortic dissection and a collapsed abdominal endograft. Subsequently, the patient was taken to the operating room and treated with a thoracic endovascular aortic repair, abdominal aortic cuff, and an iliac stent. Our study details this case and thoroughly reviews similar cases in the literature.

Aortic dissection is a rare, life-threatening event with an annual incidence of approximately 6 cases per 100,000. 1 Type B acute aortic dissections (TBAD) account for 25% to 40% of all aortic dissections. 1 Thoracic endovascular aortic repair (TEVAR) promotes highly effective aortic remodeling in acute and subacute TBAD. 2 Although collapsed thoracic aortic endografts have been welldocumented, 3 abdominal aortic stent graft collapse is quite infrequent. We present the rare case of a TBADinduced collapse of an infrarenal endovascular aortic repair (EVAR), resulting in lower limb ischemia, successfully treated with TEVAR, an abdominal aortic cuff, and iliac stenting.

CASE REPORT
Informed consent was obtained for the publication and presentation of this case report and associated images.

Imaging.
A computed tomography angiogram revealed a thoracic aortic dissection originating from just distal to the left common carotid artery extending to the left common femoral artery. The infrarenal aortic graft and the left iliac distal landing zone were compressed by the false lumen of the dissection (Fig 2). The proximal descending aorta was dilated to 4.5 cm.
There were several high-risk elements of the dissection, including an entry tear in the inner aortic curvature of more than 10 mm, a descending false lumen diameter or more than 22 mm, and a patent, round false lumen with an elliptical true lumen.
The patient was started on esmolol drip for blood pressure control. A TEVAR with prophylactic left subclavian revascularization was planned.
Operation. The patient underwent left carotid artery to left subclavian artery bypass in preparation for concomitant zone 2 TEVAR deployment.
Bilateral femoral access was obtained under ultrasound guidance. Using the preclose technique, two ProGlide devices were deployed on the right. From the right femoral access, using a glidewire and glide catheter combination, the collapsed stent graft was traversed successfully. The wire position in the true lumen was confirmed with intravascular ultrasound examination and angiography. A Lunderquist wire was then positioned   remodeling with false lumen thrombosis (Fig 3). The patient was able to resume his daily activities.

DISCUSSION
Stent graft collapse is a rare complication after EVAR. Other etiologies beyond TBAD for stent graft collapse have included angulation of the aortic neck, oversized endografts, stent migration, and type A dissection. 4 Similar cases of collapsed abdominal EVAR stent grafts from TBAD have been sparsely reported in the literature. Of the 12 reported cases we found, 11 patients (92%) were male and the mean patient age was 70.8 years. The median time to presentation after the abdominal EVAR was 13 months. Patients presented most frequently with acute abdominal pain, limb ischemia, back pain, and/or paraplegia. Four patients (33%) died en route to the hospital or shortly after reoperation. These 12 cases are summarized in the Table. [5][6][7][8][9][10][11][12][13][14][15] The etiology of TBAD in patients with abdominal EVAR remains unknown. We hypothesize that our case was a primary TBAD, with a high-pressured false lumen compressing and collapsing the abdominal aortic stent graft. The abdominal endograft may have prevented a reentry tear, leading to a mean false lumen pressure that was much greater than the true lumen pressure. 4,8 Furthermore, the remodeling of an undetected aortic dissection may be a precursor for infrarenal AAA and the two events may not always be mutually exclusive. 16 Although the stent graft material might play a role in susceptibility of collapse, the number of reported cases is too small to draw definitive conclusions. Both nitinol, as in the current case, and stainless steel 6 devices have been reported to collapse. TEVAR collapse has also been reported with a median time to graft collapse within the first 2 postoperative weeks. 3 High radial force devices have been used to repair these collapsed thoracic grafts. Further research is necessary to determine the precise etiology and incidence of TBADinduced abdominal stent graft collapse. A consensus on treatment strategies for abdominal EVAR collapse has not been established. Previously reported successful repair strategies include axillofemoral bypass, 9,11,15 open abdominal aortic repair, 9,15 and TEVAR of the proximal tear. 6,7,10,12,15 The endovascular treatment of abdominal endograft collapse, generally with an aortic balloon and/or cuff, is a viable approach. 6,7 In our case, an aortic cuff was placed just below the level of the renal arteries. We did not believe that balloon remodeling alone would suffice for long-term fixation of the stent graft in the setting of continued aortic remodeling.
After TEVAR and infrarenal aortic cuff placement on the Gore Excluder device, perfusion in our patient's left common iliac artery was still compromised; thus, we elected to place a Viabahn Balloon Expandable 11 Â 79 mm graft. Iliac stenting has been reported for the treatment of limb ischemia in other cases of aortic stent graft collapse. 10,14 Balloon thromboembolectomy has also been described to reline the iliac limb of the collapsed EVAR. 12 In contrast, in some reports of EVAR collapse with severe lower extremity ischemia, normal perfusion of the iliac arteries has returned simply after reestablishing the structure of the aortic stent graft. 6 This treatment discrepancy suggests that the use of iliac stents should be an intraoperative case-dependent decision in these clinical scenarios.