Successful Hybrid Treatment of Stent-Graft Migration Caused by Type B Aortic Dissection after Endovascular Aortic Aneurysm Repair: A Case Report

Type B Acute Aortic Dissection as a Perioperative Complication after an Endovascular Abdominal Aortic Repair

Type B aortic dissection (TBAD) is a rare but catastrophic complication of endovascular aneurysm repair (EVAR). We report two cases of TBAD occurring in the perioperative period of EVAR. The intraoperative and postoperative courses were unremarkable. Routine postoperative computed tomography angiography (CTA) revealed TBAD. Conservative treatment was successful, and no adverse aortic events occurred. TBAD that occurs in the perioperative period is likely to be iatrogenic in origin, uncomplicated, and managed with medical therapy: its prognosis is better than when the condition develops in the midterm postoperative period.

Acute Type A Dissection Causing Impending Rupture of Abdominal Aortic Aneurysm Previously Treated with EVAR

This report describes the rapid expansion of a previously excluded abdominal aortic aneurysm (AAA) following type A aortic dissection repair in a 74-year-old male. Following successful Hemiarch replacement, CT angiography (CTA) showed residual dissection throughout the thoracoabdominal aorta, which had created a proximal endoleak at the prior endovascular stent graft resulting in the rapid growth of the residual AAA sac. Urgent thoracic endovascular aortic repair (TEVAR) did not fully obliterate false lumen flow allowing further unstable expansion of the AAA and abdominal pain. This was ultimately managed with an open replacement of the infrarenal neck with a Dacron interposition graft sewn to the prior EVAR. Postoperative CTA showed resolution of the false lumen communication to the infrarenal AAA and no further endoleak. Open interposition AAA neck replacement is a possible treatment for new-onset endoleak in patients with aortic dissection following prior infrarenal EVAR.

Hemodynamic performance within crossed stent grafts: computational and experimental study on the effect of cross position and angle

Background and aims

The crossed limbs stent graft technique is regularly employed to treat abdominal aortic aneurysm patients with unfavorable aneurysm necks or widely splayed common iliac arteries. This article numerically evaluates the hemodynamic performance of the crossed limbs strategy by analyzing numerical simulations and conducting experiments using two series of idealized bifurcated stent grafts with different cross angles and cross positions.

Results

Results demonstrated that the absolute helicity at outlets decreased with increased cross angles and increased with decreased cross positions. The time-averaged wall shear stress remained approximately unchanged, whereas the oscillating shear index and relative resident time decreased slightly when the cross angle increased and cross position decreased in iliac grafts. Additionally, both numerical and in vitro experimental results indicate the displacement force acting on the stent graft gradually increased as cross angles increased and cross positions decreased. Results further indicated that strip areas with a high oscillating shear index and high relative resident time, which may be vulnerable to thrombosis formation, exist along the outer surface of the iliac artery grafts.

Conclusion

Given this information, the optimal crossed limbs configuration may contain a small cross angle and low cross position; however, low cross positions may increase the risk of migration.