Compression and spontaneous re-expansion of a thoracic endograft placed for acute, traumatic injury of the proximal thoracic aorta

An In Vitro Phantom Study on the Role of the Bird-Beak Configuration in Endograft Infolding in the Aortic Arch

Purpose: To assess endograft infolding for excessive bird-beak configurations in the aortic arch in relation to hemodynamic variables by quantifying device displacement and rotation of oversized stent-grafts deployed in a phantom model. Methods: A patient-specific, compliant, phantom pulsatile flow model was reconstructed from a patient who presented with collapse of a Gore TAG thoracic endoprosthesis. Device infolding was measured under different flow and pressure conditions for 3 protrusion extensions (13, 19, and 24 mm) of the bird-beak configuration resulting from 2 TAG endografts with oversizing of 11% and 45%, respectively. Results: The bird-beak configuration with the greatest protrusion extension exhibited the maximum TAG device displacement (1.66 mm), while the lowest protrusion extension configuration led to the minimum amount of both displacement and rotation parameters (0.25 mm and 0.6°, respectively). A positive relationship was found between the infolding parameters and the flow circulating in the aorta and left subclavian artery. Similarly, TAG device displacement was positively and significantly (p<0.05) correlated with the pulse pressure for all bird-beak configurations and device sizes. However, no collapse was observed under chronic perfusion testing maintained for 30 days and pulse pressure of 100 mm Hg. Conclusion: These findings suggest that endograft infolding depends primarily on the amount of aortic pulsatility and flow rate and that physiological flows do not necessarily engender hemodynamic loads on the proximal bird-beak segment sufficient to cause TAG collapse. Hemodynamic variables may allow for identification of patients at high risk of endograft infolding and help guide preventive intervention to avert its occurrence.

Endograft collapse after thoracic endovascular aortic repair

PURPOSE

To provide insight into the causes, timing, and optimal management of endograft collapse after thoracic endovascular aortic repair (TEVAR).

METHODS

A comprehensive review was conducted of all published cases of endograft collapse after TEVAR identified using Medline, Cochrane Library Central, and EMBASE. In total, 32 articles describing 60 patients (45 men; mean age 40.6 ± 17.2 years, range 17-78) with endograft collapse were included. All data were extracted from the articles and systematically entered into a database for meta-analysis.

RESULTS

In the 60 cases of endograft collapse, TEVAR had most commonly been applied to repair traumatic thoracic aortic injuries (39, 65%), followed by acute and chronic type B aortic dissections (9, 15%). The median time interval between TEVAR and diagnosis of endograft collapse was 15 days (range 1 day to 79 months). On average, the collapsed endografts were oversized by 26.7% ± 12.0% (range 8.3%-60.0%). Excessive oversizing was reported as the primary cause of endograft collapse in 20%, and a small radius of curvature of the aortic arch was responsible for 48% of the cases. The 30-day mortality was 8.3%, and the freedom from procedure-related death at 3 years after diagnosis of stent-graft collapse was 83.1% for asymptomatic patients compared with 72.7% for patients who had symptoms at diagnosis (p=0.029).

CONCLUSION

Endograft collapse typically occurs shortly after TEVAR, most frequently after endovascular repair of traumatic aortic injury. A high level of suspicion for endograft collapse in the first month after TEVAR, as well as further improvement of current endovascular devices, may be required to improve the long-term outcomes of patients after TEVAR.