Treatment of Infolding Related to the Gore TAG Thoracic Endoprosthesis

Infolding of fenestrated endovascular stent graft

We report a case of infolding of a fenestrated stent graft involving the visceral vessel segment after a juxtarenal abdominal aorta aneurysm repair. The patient remains free of any significant endoleak, and the aortic sac has shown regression. The patient remains asymptomatic, with no abdominal pain, with normal renal function, and without ischemic limb complications. We hypothesize that significant graft oversizing (20%-30%) with asymmetric engineering of the diameter-reducing ties may have contributed to the infolding. Because of the patient's asymptomatic nature and general medical comorbidities, further intervention was deemed inappropriate as the aneurysmal sac is regressing despite the infolding.

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.

Early stent fracture and collapse of a Zenith TX2 thoracic stent graft used for traumatic aortic rupture

Structural failure and collapse of thoracic stent grafts may cause fatal complications that are easily overlooked on follow-up imaging. A young man with multiple injuries from a motorcycle crash was treated with endografting for an aortic transection. The clinical course was initially satisfactory but deteriorated one week after the injury and the patient died two weeks later. Autopsy and retrospective assessment of chest X-rays revealed early fractures and collapse of the stent graft that had been overlooked and may have contributed to the lethal outcome. The design of thoracic stent grafts needs to be improved for treatment of traumatic aortic transection. Careful follow-up of these patients is warranted.

Recurrent collapse of a Gore TAG endograft in treating an aortoesophageal fistula

As the utility of the Gore TAG endograft expands in an off-label fashion to include various aortic pathologies like aortoesophageal fistulas (AEFs), more TAG endograft collapses are being described in the literature. We report a case of a recurrent endograft collapse in a patient with a right-sided aortic arch, who was treated for a hemorrhage from an AEF. One month following the initial endograft placement, angiography detected infolding of the endograft, which was then re-expanded with another endograft. Four months later, the patient developed an acute biventricular dysfunction with an ejection fraction (EF) less than 20%. Cardiac catheterization revealed that the patient had an 80 mmHg pressure gradient across the endograft suggesting another collapse. A balloon-expandable stent was used to re-expand the endografts and restore the EF. On follow-up, the patient's endograft has remained patent without evidence of further collapse.

Delayed endovascular treatment of descending aorta stent graft collapse in a patient treated for post- traumatic aortic rupture: a case report

BACKGROUND

We report a case of delayed endovascular correction of graft collapse occurred after emergent Thoracic Endovascular Aortic Repair (TEVAR) for traumatic aortic isthmus rupture.

CASE PRESENTATION

In 7th post-operative day after emergent TEVAR for traumatic aortic isthmus rupture (Gore TAG® 28-150), a partial collapse of the endoprosthesis at the descending tract occurred, with no signs of visceral ischemia. Considering patient's clinical conditions, the graft collapse wasn't treated at that time. When general conditions allowed reintervention, the patient refused any new treatment, so he was discharged.Four months later the patient complained of severe gluteal and sural claudication, erectile disfunction and abdominal angina; endovascular correction was performed. At 18 months the graft was still patent.

DISCUSSION AND CONCLUSION

Graft collapse after TEVAR is a rare event, which should be detected and treated as soon as possible. Delayed correction of this complication can be lethal due to the risk of visceral ischemia and limbs loss.

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.

Impact of aortic repair based on flow field computer simulation within the thoracic aorta

Purpose of this computational study is to examine the hemodynamic parameters of velocity fields and shear stress in the thoracic aorta with and without aneurysm, based on an individual patient case and virtual surgical intervention. These two cases, case I (with aneurysm) and II (without aneurysm), are analyzed by computational fluid dynamics. The 3D Navier-Stokes equations and the continuity equation are solved with an unsteady stabilized finite element method. The vascular geometries are reconstructed based on computed tomography angiography images to generate a patient-specific 3D finite element mesh. The input data for the flow waveforms are derived from MR phase contrast flow measurements of a patient before surgical intervention. The computed results show velocity profiles skewed towards the inner aortic wall for both cases in the ascending aorta and in the aortic arch, while in the descending aorta these velocity profiles are skewed towards the outer aortic wall. Computed streamlines indicate that flow separation occurs at the proximal edge of the aneurysm, i.e. computed flow enters the aneurysm in the distal region, and that there is essentially a single, slowly rotating, vortex within the aneurysm during most of the systole. In summary, after virtual surgical intervention in case II higher shear stress distribution along the descending aorta could be found, which may produce more healthy reactions in the endothelium and benefit of vascular reconstruction of an aortic aneurysm at this particular location.

Unsuccessful treatment of a collapsed thoracic stent graft by Palmaz stent

A Gore TAG Excluder stent graft was deployed in a 35-year-old woman for an isthmic saccular aneurysm. At 12-hour follow-up, we diagnosed a proximal collapse. A Palmaz stent was used to reopen the proximal segment. Two months later, she presented with a transient ischemic attack (embolic process) related to a suboptimal apposition of the Palmaz stent in the distal aortic arch. This led to open surgical replacement of the ascending aorta and aortic arch with reimplantation of the supraaortic branches. Reopening of a stent graft collapse with a Palmaz stent might be a short-term solution; however, its presence can lead to embolic complications.

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

The collapse or compression of a thoracic endograft represents a potentially fatal complication that normally requires endovascular or open surgical correction. We present the first report of a compressed thoracic endograft that spontaneously re-expanded without surgical or endovascular intervention. The possible mechanism for the compression and re-expansion of the endograft will be discussed. The unique behavior of this endograft offers insight into an important failure modality for thoracic endografts.