The Vanguard Endovascular Stent-graft: Mid-term Results from a Single Centre

Overall outcome after endovascular aneurysm repair with a first-generation stent graft (Vanguard): A 20-year single-center experience

OBJECTIVE

The problems with first-generation stent grafts for endovascular aneurysm repair are well known, but their long-term outcome remains to be established. The purpose of the study was to characterize the outcome of patients treated for abdominal aortic aneurysm (AAA) with a first-generation stent graft, Vanguard (Boston Scientific, Natick, Mass), in a single academic center with a follow-up of up to 20 years.

METHODS

There were 48 AAA patients electively treated with a Vanguard stent graft between February 1997 and November 1999. The patients were monitored annually until the end of 2018. The outcomes were overall survival and the number of graft-related complications and reinterventions.

RESULTS

The mean age was 70 years (range, 54-85 years), and the mean follow-up was 107 months (range, 6-262 months). All stent grafts were successfully implanted, but 90% of the patients encountered graft-related complications during follow-up. The most common complications were endoleaks (type I, 27%; type II, 29%; type III, 31%), stent fracture (46%), graft thrombosis (31%), and migration (40%). A total of 40 (83%) patients required a secondary procedure during long-term follow-up. The endovascular method for treating the complication was successful in 73 (87%) of 84 cases. There were no primary conversions, but 10 patients (21%) required a late conversion. In five cases, the complications required relining with a newer device. There were four AAA ruptures (8.3%), two of them fatal. The cumulative overall survival rates were 94%, 69%, 33%, 15%, and 13% at 1 year, 5 years, 10 years, 15 years, and 20 years, respectively.

CONCLUSIONS

The use of the Vanguard, a first-generation stent graft, was associated with multiple graft-related complications. However, these complications could mainly be treated by endovascular means. The Vanguard stent graft is a good example of how new technology can cause unpredictable problems that can magnify the workload and endanger the patient's well-being even decades after the initial procedure.

Identifying and addressing the limitations of EVAR technology

INTRODUCTION

Endovascular aortic repair (EVAR) has improved over the last two decades. Approximately 80% of the patients presenting with an abdominal aortic aneurysm (AAA) is nowadays primarily treated with EVAR.

AREAS COVERED

In this review, the differences between endovascular and open repair, the clinical characteristics needed for EVAR, the role of clinical imaging and the developments in EVAR technology will be discussed. Early mortality is lower in EVAR as compared to open repair, whereas this benefit is lost after 3 years postoperatively. EVAR comes with a high reintervention rate, with endoleak being the most important predictive factor for reintervention. Expanding technical possibilities have allowed surgeons to choose from a palate of endovascular approaches in aneurysm patients with challenging anatomies.

EXPERT COMMENTARY

Although EVAR has taken a giant leap forward in development, the new developments have seemed to surpass the long-term limitations with older devices. It is important to start focusing on the current limitations of EVAR, in particular the durability of devices in the human variable anatomic and dynamic environment.

Large infra-renal abdominal aortic aneurysms: endovascular vs. open repair--single centre experience

Endovascular aneurysm repair (EVAR) has become an established alternative to open repair (OR). We present a consecutive series of 486 elective patients with large infra-renal aortic abdominal aneurysm, comparing OR with EVAR. Prospective data collected during an 8-year period from January 1997 to October 2005 was reviewed. Statistical analysis performed using SPSS data editor with chi(2) tests and Mann-Whitney U-tests. There were 486 patients with 329 OR (293 males, 36 females) with median age of 72 years with median diameter 6.3 cm and 157 EVAR (148 males, 9 females) with median age 75 years with median diameter 6.1 cm. Mortality was 13 (4%) for OR and 5 (3.2%) for EVAR (three of whom were in the UK EVAR 2 trial). Blood loss was significantly less for EVAR 500 ml vs. 1500 ml for OR. Sixty-five (19.8%) patients with OR had significantly more peri-operative complications compared with 14 (8.9%) with EVAR. The length of stay in hospital was significantly less for EVAR. This non-randomised study shows that although EVAR does not have a statistically significantly lower mortality, it does have statistically significantly lower complication rates compared with OR. EVAR can be achieved with good primary success, but long-term follow-up is essential to assess durability.

The Mid-term Effect of Bare Metal Suprarenal Fixation on Renal Function Following Endovascular Abdominal Aortic Aneurysm Repair

OBJECTIVE

The aim of this study was to assess the mid term effect of proximal bare metal fixation design on renal function in patients undergoing endovascular repair (EVR) of abdominal aortic aneurysm (AAA).

METHODS

Consecutive EVR patients for AAA from December 1995-2001 were included and grouped to either infrarenal (Group 1) or uncovered suprarenal (Group 2) fixation. Peri-operative renal function and at 6, 12 and 24 months was determined by serum creatinine (sCr mmol l(-1)) and Cockroft-Gault creatinine clearance (CrC ml min(-1)). Changes in renal function were compared using non-parametric analysis.

RESULTS

Of the 179 EVR procedures during this six-year period, paired renal data was available for 135 patients at a minimal follow-up of 6 months (Gp1, n = 63; Gp2, n = 72). Median pre-EVR sCr and CrC were 113, 57 in Group 1 and 108, 58 in Group 2, p = NS. There was no significant deterioration in renal function within or between either group at 2 years post-EVR: median sCr, CrC values were 118, 56 (Group 1) and 111, 56 (Group 2), all p = NS.

CONCLUSION

This study suggests mid-term renal function remains unaffected following EVR of AAA, irrespective of proximal fixation type. Designs to improve stent durability and EVR applicability do not appear to compromise renal function.

Late type III endoleak from graft erosion of an Excluder stent graft: A case report

We report a case of a late type III endoleak from a hole in the expanded polytetrafluoroethylene graft material of an Excluder bifurcated stent-graft approximately 12 months after implantation. The endoleak was successfully repaired by relining the defect site with an Excluder iliac limb. To our knowledge, this is the first reported case of late graft-material related Type III endoleak involving the Excluder device.

Stent-Grafts for Unruptured Abdominal Aortic Aneurysms: Current Status

Aortic stent-grafts were introduced at the beginning of the 1990s as a less invasive method of dealing with aortic aneurysms in patients with poor cardiovascular reserve. The numbers of procedures performed worldwide has increased exponentially despite the current lack of any substantial evidence for long-term efficacy in comparison with the gold standard of open surgical grafting. This review summarizes the evolution of the abdominal aortic stent-graft, the techniques used for assessment and deployment, and the effect of the procedure on both the patient and the device. The recent publication of two national multicenter trials has confirmed that the endovascular technique confers a 2.5-fold reduction in 30-day mortality in comparison with open surgery. However, over 4 years of follow-up, there is a 3-fold increase in the risk of reintervention and the overall costs are 30% greater with endovascular repair. Although the improvement in aneurysm-related mortality persists in the mid-term, because of the initial reduction in perioperative mortality, the all-cause mortality rate at 4 years is actually no better than for open surgery. Longer-term data from the randomized trials are awaited as well as results from the latest trials utilizing state-of-the-art devices. Whilst the overall management of abdominal aortic aneurysms has undoubtedly benefited from the introduction of stent-grafts, open repair currently remains the gold standard treatment.

Embolization-driven Occlusion of the Abdominal Aortic Aneurysmal Sac as the Basis of Prevention of Endoleaks in a New Swine Model

OBJECTIVES

To assess the effect of a new polymer in embolization of endoleaks using an animal model.

METHODS

A modified aortic stent-graft was placed in 20 pigs. Embolization was performed at the time of graft insertion with non-cytotoxic n-butyl-2-cyanoacrylate-metacryloxysulpholane and lipiodol (0.2:0.8ratio, 2 ml). Angiography, scanning electron microscopy and immuno-histochemistry were obtained at day 0, 1 week and 3 months.

RESULTS

In control animals both type I and II endoleaks were demonstrated. In treated animals, neither type-I nor type-II endoleaks were observed and a fibro-proliferative response was demonstrated within the aneurysm thrombus.

CONCLUSIONS

Host vascular responses govern the fate of the excluded aneurysm. Embolization of the sac and feeding arteries with non-cytotoxic glue sealed all occlusions by stimulating a massive restenosis-like process.

Initial and Midterm Results for Repair of Aortic Diseases With Handmade Stent Grafts

BACKGROUND

The purpose of this study was to determine the initial and midterm results for repair of thoracic and abdominal aortic diseases using handmade stent-grafts (SGs).

METHODS AND RESULTS

Between 1999 and 2004, 41 consecutive patients (31 patients with thoracic and 10 patients with abdominal aortic disease) underwent endovascular stent-graft repair using handmade SGs. The follow-up averaged 24.8+/-17.6 months. The technical and initial clinical success rates were 82.9% (34/41) and 80.5% (33/41), respectively. Primary type I or III endoleaks occurred in 12.2% (5/41) of the patients. The hospital mortality rate was 4.9% (2/41). Persistent type I or III endoleaks occurred in 9.8% (4/41) and SG migrations occurred in 4.9% (2/41) of the patients. Open surgical conversion was undertaken in 12.2% (5/41) of the patients because of an endoleak and/or migration. The mean change observed in the aneurysm diameter was -6.2+/-10.5 mm, and shrinkage in the diameter occurred in 51.4% (18/35) of the cases. There was 1 patient death because of aneurysm rupture. Neither stent fracture nor graft hole was observed. The overall clinical success rate during follow-up was 78.0% (32/41).

CONCLUSION

The initial and midterm results obtained after repair of the aortic diseases using handmade SGs were considered to be satisfactory. More surgical experience and long-term patient follow-up are both required to further reassess the effect of this treatment.

Late problems at the proximal aortic neck: Migration and dilation

Migration is a late-term complication of endovascular aneurysm repair (EVAR) evidenced by downward slippage of the endograft. The etiology of migration may be inherent to problems with endograft fixation, although aortic neck dilation may also play a role. Devices with active fixation (ie, hooks and barbs) possess an additional mechanism of fixation and may better resist migration. Aortic neck dilation after EVAR is significant in a subset of patients and may be related to neck degeneration. Excessive oversizing of endografts may contribute to dilation and migration and is, therefore, not recommended. Migration should be treated when the overlap between the endograft and aortic neck is less than 10 mm or when associated with clinically significant events such as type I endoleak or aneurysm expansion. Failure to treat migration could lead to repressurization and subsequent rupture of the aneurysm.