A preliminary analysis of late structural failures of the Navion stent graft in the treatment of descending thoracic aortic aneurysms

OBJECTIVE

Patients in the Valiant Evo U.S. and international clinical trials had positive short-term outcomes; however, late structural failures, including type IIIb endoleaks have been recently discovered. Type IIIb endoleaks are serious adverse events because the repressurization of the aneurysm sac increases the risk of rupture. The purpose of the present study was to detail the imaging patterns associated with the structural failures with the aim of increasing awareness of failing graft presentation, early recognition, and prompt treatment.

METHODS

The Valiant Evo clinical trial was a prospective, single-arm investigation of a thoracic stent graft system. With the recent late structural failures, sites were requested to submit all available imaging studies to date to allow the core laboratory to assess for structural failures such as type IIIb endoleaks, stent ring fractures, and stent ring enlargement. Of the 100 patients originally enrolled in the trial from 2016 to 2018, the core laboratory assessed the imaging studies performed at ≥1 year for 83 patients.

RESULTS

No structural failures of the graft were reported through 1 year of follow-up. At 1 to 4 years, graft structural failures were detected in 11 patients with descending thoracic aortic aneurysms. Of the 11 patients, 5 had a type IIIb endoleak. Four of the five had imaging findings showing stent fractures consistent with the location of the graft seam and one had a type IIIb endoleak attributed to calcium erosion with no stent fracture or ring enlargement. Of the four patients with stent fracture in line with the graft seam, three underwent a relining procedure that successfully excluded the type IIIb endoleak. One of these three patients died 4 days later of suspected thoracic aortic rupture because the distal thoracic endovascular aortic repair extension had been landed in a previously dissected and fragile section of the aorta. The remaining six patients had had stent ring enlargement. One of the six patients had had persistent aneurysm expansion from the time of implantation onward and had died of unknown causes. The remaining five patients have continued to be monitored.

CONCLUSIONS

In the present preliminary analysis, the imaging patterns associated with type IIIb endoleaks, stent fractures, and stent ring enlargement appear to be related to the loss of seam integrity or detachment of the stent rings from the surface of the graft material. The imaging patterns we have detailed should be closely monitored using computed tomography angiography surveillance to allow structural failures to be promptly identified and treated.

Case Report of Late Type IIIb Endoleak with Willis Covered Stent (WCS) and Literature Review

OBJECTIVE

We report a case of late type IIIb endoleak with Willis covered stent (WCS) developed 14 months after endovascular paraclinoid aneurysm repair.

METHODS

A 52-year-old woman presented with episodic headache, caused by a giant paraclinoid aneurysm. She underwent a successful 3.5 x 16mm WCS positioning to treat the aneurysm. Fourteen months later, the patient was admitted with the same symptoms. Digital subtraction angiography examination showed recurrence of the aneurysm, which was similar to the preoperative one. DynaCT (Siemens, Erlangen, Germany) indicated the intact of the metal structure of the stent without migration. Type IIIb endoleak (defect in the graft fabric) was confirmed with a whole aneurysm neck located in the middle part of the stent. The type IIIb endoleak was treated with another WCS (4.0 x 16mm). The immediate digital subtraction angiography imaging indicated that the endoleak disappeared and the aneurysm was completely occluded. Re-examination done 1 year after the second treatment showed a complete exclusion of the aneurysm sac.

CONCLUSIONS

Type IIIb endoleaks can be safely treated by the endovascular positioning of another WCS. Continuous surveillance after endovascular paraclinoid aneurysm repair for intracranial aneurysms is warranted to make ensure the safety of WCS.

Aneurysm sac enlargement 16 years after endovascular aortic aneurysm repair due to late type IIIb endoleak: A case report

INTRODUCTION

We report a case with delayed aneurysm sac enlargement 16 years after EVAR due to late type IIIb endoleak.

PRESENTATION OF CASE

An 84-year-old man was referred to our hospital with an aneurysm sac enlargement after endovascular aortic aneurysm repair (EVAR), which had been performed at another hospital 18 years earlier using the Zenith endograft. Computed tomography (CT), after EVAR had shown significant sac shrinkage. However, the patient presented with delayed aortic aneurysm enlargement due to an assumed endoleak. Duplex ultrasound showed a type IIIb and a type Ib endoleak. We performed a re-intervention with an AFX endograft, for relining due to persistent type IIIb endoleak.

DISCUSSION

Compared with the type IIIB endoleaks discussed in past reports, this case occurred with a much longer delay. Although CT could not identify the type of endoleak, duplex ultrasound led us to diagnose the type IIIb endoleak.

CONCLUSION

Relining using an ePTFE endograft may be considered an effective procedure for type IIIb endoleaks. Duplex ultrasound is useful for determining endoleak types.

Hybrid repair of rare type IIIb endoleaks from an abdominal endograft: repeatedly undetected endoleaks

We report a rare case of massive type IIIb endoleaks from an abdominal endograft, which were difficult to diagnose and required hybrid repair (including open surgery). The patient had previously undergone three catheter interventions for type Ia and II endoleaks after abdominal endografting. However, the abdominal aortic aneurysm gradually enlarged and required hybrid treatment (including an open repair), to successfully perform aneurysmorrhaphy and additional endograft insertions for the massive type IIIb endoleaks.