Secondary Interventions Following Endovascular Aneurysm Repair (EVAR) and the Enduring Value of Graft Surveillance

Article Outline

• Abstract
• Introduction
• Methods
  • Statistics
• Results
• Discussion
  • Current surveillance and proposed modification
  • Intra-operative adjuncts to reduce secondary interventions
  • Timing of surveillance
  • High risk grafts for secondary interventions
  • Proposed surveillance program
  • Limitations of this study
• Conclusion
• Acknowledgements
• Conflict of Interest
• References
• Copyright

Abstract 

Objective

Lifelong imaging surveillance is currently recommended for all patients following endovascular aortic aneurysm repair (EVR). The modality, timing and overall necessity of surveillance has recently been brought into question. This review reports contemporary secondary intervention rates and explores surveillance imaging pick-up rates and reports the evidence supporting modified EVR surveillance programs.

Design

Systematic review of literature (2002–2009) and meta-analysis of Kaplan–Meier re-intervention-free survival estimates.

Results

32 Papers were included in final analysis. 17,987 EVR cases were reported. Crude annual secondary intervention rates from the US population registries were 3.7%/year (range 1.7–4.3%). Combined re-intervention-free survival estimates, from 14 series (10,365 cases), demonstrated a linear progression with 89.9%, 86.9% and 81.5% of grafts without secondary procedures at 2, 3 and 5 years respectively.

3 Reports (1249 cases) differentiated between interventions directed by surveillance or outside surveillance protocols. Surveillance imaging alone initiated the secondary interventions in 1.4–9% of cases; >90% of EVR cases received no benefits from surveillance scans.

Discussion

Some format of surveillance following EVR probably remains necessary despite a reduction in secondary interventions with modern stent-grafts. Surveillance should be targeted at those stent-grafts and patients at high risk of complications. Further work is justified to identify this group.

Keywords: EVAR, AAA, Aneurysm, Surveillance: secondary intervention

Back to Article Outline

Introduction 

Endovascular abdominal aortic aneurysm repair (EVR) is becoming more widely applied to elective abdominal aortic aneurysm (AAA) repair due to its lower aneurysm-related operative and mid-term mortality rates.¹ However this technique incurs additional costs.² These costs are amplified when graft surveillance and secondary intervention expenses are added to the equation. Intensive radiological surveillance is not routine following open surgery.

Graft surveillance following EVR is currently universally recommended, although there are no standard regimes. The rationale for surveillance is prevention of AAA rupture or AAA/stent-graft associated morbidity and mortality.

Intensive surveillance regimens may be the consequence of early, first generation graft failures.³ Evidence is required to assure the licensing bodies and profession of the durability of modern stent-grafts. The indications for secondary interventions have changed over time with the recognition of factors associated with stent-graft failure, AAA rupture and other complications.

Computed tomography (CT) scanning was the mainstay of graft surveillance in early EVR. There are alternative imaging modalities although none is ideal. Many centres have proposed a Duplex led surveillance program, although this can be user-dependent. Magnetic resonance imaging, albeit free from ionizing radiation, is expensive, has limited availability, incompatible with some grafts and gadolinium can be nephrotoxic. Implantable sensor technology is still in its infancy.

The relative value of lifelong surveillance in patients who have undergone EVR has become an important topic. Repeated CT scanning exposes the patient to potential carcinogenic risks associated with ionizing radiation exposure. The estimated lifetime attributable risk (LAR) of death from cancer following an abdominal CT scan in a patient >50 years is 0.02%; small, yet cumulative which can become significant with repeated scanning.⁴ Repetitive use of iodinated contrast can have a cumulative deleterious effect on renal function; especially in the elderly and those patients with pre-existing renal impairment.⁵

Long-term post-placement surveillance, diagnostic studies and possible secondary procedures have been shown to increase the global cost of EVR by nearly 50%.⁶ Approximately 65% of follow-up costs have been attributed to CT scanning.⁷ Typical post-EVR CT and MR scans cost approximately £750–1000 and £1000–1300 respectively. In comparison, post-EVR surveillance color-flow duplex ultrasound (CDU) costs approximately £300–400.⁸ To develop the role of EVR cost-effectiveness needs to be improved,⁶ reducing unnecessary expenditure on surveillance is one possibility.

This systematic review examines the current rates of secondary intervention following elective EVR. It explores whether these interventions were initiated by the surveillance program or patient symptoms. Although patients whose AAAs go on to rupture despite EVR have a relatively good outcome;⁹ the optimum modality of surveillance should be determined to prevent rupture.

Back to Article Outline

Methods 

Medline, Embase and Cochrane library databases were interrogated. The keyword searches were “EVAR”, “Endovascular” and “surveillance” and/or “secondary intervention”. Abstracts from all articles that reported secondary interventions following EVR published 2002–2009 were reviewed. Further potentially useful articles were identified through scrutiny of references. Articles were excluded if they reported <100 cases of EVR, reported <1 year median follow-up or were published outside the English language literature. Retrieved papers were examined for rates of secondary intervention and endoleak warranting treatment. The authors explored each report for secondary interventions directed by surveillance findings or clinical symptoms.

Statistics 

Cumulative survival data were converted to marginal data reflecting the annual probabilities of re-intervention within each trial. Missing annual data from individual trials were interpolated using available biannual data, with the assumption of a constant re-intervention rate within the interval. A Kaplan–Meier product estimator was then calculated multiplying the median derived values for (1-annual probability of re-intervention) to obtain a cumulative Kaplan–Meier estimate of re-intervention-free survival. Confidence intervals for the estimate were obtained by applying the same calculation to the inter quartile values of the derived annual probability of re-intervention.

Back to Article Outline

Results 

473 Papers were screened for retrieval. Following review of abstracts 53/473 (11%) papers were selected for further assessment. 32 Papers met the inclusion criteria (Fig. 1). A total 17,987 EVR cases are reported (Table 1). The crude annual secondary intervention rate in the EVAR trials was 6%/year. Population registries published since the EVAR trials report lower annual rates of intervention with median 3.7%/year (range 1.7–4.3%/year).

• 
  • View Large Image
  • Download to PowerPoint

• Figure 1 

  QUORUM chart demonstrating literature search outcomes.

Table 1. Studies retrieved demonstrating secondary interventions.

>100 cases, published 2002 or later.

Examining the independent case-series there is a trend of reducing secondary intervention rates. Studies reporting in 2003 present a median secondary intervention rate of 6.6%/year (range 3.4–48). This compares to 4.5%/year (range 3–12.8) in the 2009 case-series. This may be attributable to decreased interventions for endoleak as understanding has developed, specifically type II endoleaks, or improved graft technology.

Three out of 32 papers (1249 cases) attempted to differentiate between secondary interventions directed by surveillance findings, and those as a consequence of patient symptoms (Table 1). They described between 1.4 and 9% of patients undergoing interventions as a result of surveillance findings. Therefore over 90% of all patients receive no benefit from post-EVR surveillance. Two papers, Black et al. and Karthikesalingam et al., described the method of patient presentation for secondary intervention. In the first series of 417 patients, 4/6 endoleaks presented symptomatically between surveillance intervals.¹⁰ In the second series 36/81 (44%) of patients requiring secondary treatments presented with pain either from the aneurysm or claudication.

Verhoeven et al. reported that 66% of their re-interventions were elective and 34% emergent.¹¹ The majority of their acute interventions were due to acute leg ischaemia from graft limb kink or occlusion.

Cumulative re-intervention-free survival estimates were available from 14 trials (Table 2) Only 2 studies provided data to 7 years;¹², ¹³ the remainder were extrapolated to 7 years by assuming a constant re-intervention rate from the last available annual interval of each study (Fig. 2). This demonstrates a linear drop-off in re-intervention-free survival after EVR. Combined re-intervention-free survival estimates confirm 94%, 89.9%, 86.9%, 84.9% and 81.5% of grafts do not require secondary procedures at 1, 2, 3, 4 and 5 years, respectively. No specific failure time is identified that would correlate with graft material failure or native vessel disease progression within this period of follow-up.

Table 2. Raw survival data from 14 studies.

n=number still under observation.

Data presented as probability of re-intervention-free survival (standard error).

• 
  • View Large Image
  • Download to PowerPoint

• Figure 2 

  Median and inter quartile Kaplan–Meier estimates of re-intervention-free survival. Dotted lines: 1st quartile and 3rd quartile.

Back to Article Outline

Discussion 

The requirement for secondary interventions after EVR appears to continue throughout the lifetime of the graft, necessitating a surveillance strategy. Yet it appears only a small percentage (<10%) of all EVR patients benefit from post-deployment graft surveillance. This is an important finding as the additive costs of surveillance are significant in the overall investment in an EVR program.

The linear drop-off in re-intervention-free survival from 1 to 7 years is perhaps surprising. Neither the raw data nor the graphic demonstrate the early re-interventions within the first months following deployment. These are incorporated into the probabilities at year 1. The early re-interventions are where intra-operative adjuncts ensuring aneurysm exclusion are most beneficial.

At 7 years 72% of patients remain free from secondary interventions. This finding must be interpreted in the knowledge that at this extent of follow-up a large proportion of patients can become lost to follow-up. The small proportion of patients with continuing requirements for secondary interventions would be of interest to study further. Whether they constitute patients who had challenging anatomy at their primary operation and underwent graft deployment outside the industry guidelines, or they represent patients with pan-aortic disease would help understand this pattern further.

It is apparent that the requirements for secondary interventions are declining. This transition is multifactorial. Graft technology is advancing, as is understanding of management of endoleaks. Post-deployment adjuncts to ensure optimal aneurysm exclusion at the primary procedure reduce acute re-interventions. Centralization of endovascular procedures is focusing expertise and enhancing intra-departmental standards which may in turn reduce long-term complications.

Identification of the optimal markers of post-EVR aneurysm rupture will direct surveillance. Large aneurysms (>6.5cm diameter) have been shown to be associated with increased rates of aneurysm-related morbidity death post-EVR.¹⁴ A short infra-renal neck and neck angulation >45° are predictors of clinical failure or the need for re-intervention.¹⁵ These factors highlight a population where continued surveillance may be beneficial.

Post-deployment device migration has also been identified by the EUROSTAR group as a poor prognostic sign.¹⁶ Stent-strut failure has been shown to be clinically insignificant.¹⁷ The majority of type II endoleaks has been shown to be benign.¹⁸

There is a consistently low surveillance-scan pick-up rate. This is particularly highlighted in the series from Charing Cross, London, where only 1.4% of all EVR patients had a problem detected by surveillance.¹⁰ This has led to investigation into modifications in surveillance regimens.

Current surveillance and proposed modification 

Current modalities for EVR surveillance include clinical assessment, CT scanning, CDU scanning, plain abdominal radiography, magnetic resonance imaging and angiography and more recently implantable pressure sensing devices. Standard surveillance regimens include serial contrast-enhanced CT scans and plain abdominal radiographs at 1, 6 and 12 months and every 6 months thereafter for the patients' lifetime.¹⁹

CT angiography (CTA) is established as the current gold-standard for periodic monitoring of aneurysm size, migration and the detection of endoleak. Pertinent negative aspects of serial CT surveillance exist. Contrast-agent induced nephrotoxicity remains a limitation in patients with renal insufficiency. Cumulative radiation exposure from repeated studies can present a long-term carcinogenic risk.⁴

Efforts have been made to reduce the frequency of CT scanning, or replace it with alternative imaging modalities. It has been proposed that after 1 year CTA can be reserved for those patients in whom ultrasound identifies growth or persistently stable aneurysm diameter.²⁰ The value of CTA at 6 months has also been examined in a prospective study. Providing the scan at 1-month confirms no endoleaks, the 6 month scan does not identify any clinically significant findings warranting intervention.²¹ Equally the early post-procedural CTA has been questioned. It has been shown that this scan fails to influence treatment in 99% of cases.²²

Color duplex ultrasound (CDU) demonstrates aneurysms size, arterial flow, endoleaks endograft limb kinking, patency of access vessels and allows the user to examine sites distant from the endograft (e.g. assessment of wound complications). It is portable, can be performed at the bed-side, and does not require ionizing radiation.

When compared to the gold-standard CT imaging, CDU can miss up to 1/3 of endoleaks detected on CT.²³ The sensitivity for type II endoleaks is its weakness. However, the significance of a type II endoleak without associated increase in aneurysm sac size is debatable. Conservative management of type II endoleaks is not associated with an increase risk of AAA rupture.²⁴ Current recommendations target treatment of type II endoleaks for AAA sac enlargement occurring after 6 months and/or persistence after 12 months.²⁵ Yet, treatment of type II leaks has a high risk of failure and may not alter overall outcome.²⁴ An ultrasound-based surveillance program using increasing aneurysm sac size as a trigger for intervention showed no negative effects on aneurysm-related survival.²⁰

The majority of secondary procedures for graft related problems are now performed endovascularly. Catheter-based re-interventions include balloon angioplasty, stenting, proximal and distal cuff extensions, placement of a new stent-graft, embolisation of branch vessels and thrombolysis.²⁶ Conversion to open surgery and emergency secondary interventions are risk factors for morbidity and mortality.²⁷

Intra-operative adjuncts to reduce secondary interventions 

The majority of secondary interventions are performed within 30 days of deployment.²⁸ Intra-operative adjuncts that can assess completeness of aneurysm exclusion, allowing pre-emptive treatment may reduce secondary interventions and therefore the demands of surveillance. Prior to performing any completion imaging all stiff wires and long sheaths should be removed. A kink in the endograft limb that occurs when tortuous iliac arteries are allowed to return to their natural anatomical position will only become apparent once these devices are withdrawn.²⁹

A minimum standard of two-view completion angiography is required prior to completion surgery. Dynamic CT (DynaCT) has been shown to be a powerful tool for detection of endoleaks, limb compression and graft thrombosis immediately following graft deployment. It is more sensitive than uni-planar angiography and can be performed prior to the patient transferring from the operating table.³⁰

Timing of surveillance 

The goal of EVR is to prevent AAA rupture. Most AAA ruptures following EVR occur in the first 2–3 years.³¹ The LIFELINE registry reported that 85% of secondary interventions were performed within 30 days of deployment.²⁸ The majority of secondary interventions for reduced limb blood flow occurs within 90-days of deployment.¹⁰, ³² A longitudinal population study, retrospectively analyzing admission codes, reported the mean time to secondary interventions to be 447 days (±457) for angiography and 357 days (±427) for device specific treatment.³³ This correlates with a single-centre report describing secondary interventions occurring at a median 16 months post-deployment.³⁴ The efficiency of follow-up of EVR may be improved if surveillance focuses on the first 3 years.³¹

Redefining postoperative surveillance after EVR has led to recommendations for regimens whose intensity and frequency are based on early outcomes.³⁵ Recommendations have evolved based on 5-year follow-up in the US Zenith trial. In this study patients were followed-up with plain X-ray and CTA at 1, 6 and 12 months and yearly thereafter. In patients without early endoleak the 6 month imaging can be eliminated. Aortic ultrasound is suggested for long-term surveillance >1 year.

It is in the best interests of endovascular practitioners to contribute to the body of evidence regarding secondary interventions and surveillance. Groups should be encouraged to report follow-up and secondary intervention data. Clear differentiation should be made between interventions directed by surveillance findings and patient symptoms. When this data accrues, from reported case-control studies, the value of surveillance will be quantifiable. This may eventually demonstrate the need for, as was the case with infra-inguinal surveillance, a prospective randomized study of EVR surveillance.

High risk grafts for secondary interventions 

The risk of endoleak and subsequent secondary intervention increase as the manufacturers' instructions for use of endografts are breached. Complicated aortic neck anatomy including short aortic neck (<15mm),³⁶, ³⁷ excessive neck angulation (>45°)³⁸ and large aortic neck (>28mm)³⁹ have all been shown to be risk factors for proximal type 1 endoleak.

Series with large secondary intervention rates report that the majority of secondary interventions were within 30 days of deployment.²⁸ This highlights another high risk group, those with an incomplete primary procedure.

Proposed surveillance program 

Given the evidence presented in this review we propose a modified surveillance program (Fig. 3). There is strong evidence that optimal stent-graft positioning and treatment of endoleaks should be achieved at the primary operation. DynaCT will ensure confirmation of this. An early pre-discharge duplex scan will confirm the integrity of the access vessels and identify any dissection flaps or limb kinks.

• 
  • View Large Image
  • Download to PowerPoint

• Figure 3 

  Proposed surveillance program.

All patients should be entered into the surveillance program. CT scanning is replaced by Duplex scanning. CT scanning is reserved for cases liable for secondary interventions identified by type I/III endoleak or increase in aneurysm sac size. The mean time to secondary interventions is approximately 1–1½ years. We therefore propose that, if a patient completes 3 years of surveillance without detection of endoleak or sac enlargement, the patient can be discharged from follow-up.

Limitations of this study 

All studies regarding secondary interventions must be interpreted with the understanding that graft technology is evolving. Management of endoleaks is also more advanced as most stent-graft complications can be managed endovascularly. Early papers report outcomes using endografts that are now discontinued. Experience in graft deployment has also been growing during this period. The EUROSTAR dataset reported outcomes from 93 hospitals with median experience of 32 cases and relatively short follow-up.⁴⁰ Now major centres are approaching experience of over 500 cases and greater than 5-year follow-up.

The statistical model used to generate Fig. 2 relies on interpolation and extrapolation for missing data points. Until mandatory registries exist for EVR with survival data, this is the only methodology available to generate global evidence of re-intervention. The volume of cases it reports enhances its power, yet even more robust evidence is required.

Back to Article Outline

Conclusion 

The requirements for secondary intervention following EVR appear to be decreasing. This corresponds with a decreased intervention rate for endoleaks. Advances in graft technology allied to a growing understanding of endoleak management may be the explanation for this. If the need for secondary interventions continues to decline as will the requirements for intensive surveillance.

No perfect surveillance tool exists. It appears that a select group of EVR patients will continue to require secondary interventions long after deployment. Individual follow-up regimens based on peri-procedural risk stratification may be the solution for high risk groups. Low risk patients could be discharged having completed a brief uncomplicated follow-up.

Back to Article Outline

Acknowledgements 

The authors would like to thank Dr. Jan Poloniecki for his statistical advice and assistance during this project.

Back to Article Outline

Conflict of Interest 

The authors declare that there are no conflicts of interest.

Back to Article Outline

References 

1. Endovascular aneurysm repair versus open repair in patients with abdominal aortic aneurysm (EVAR trial 1): randomised controlled trial. Lancet. 2005;365(9478):2179–2186
   • View In Article
   • Abstract
   • Full Text
   • Full-Text PDF (109 KB)
   • CrossRef
2. Blackhouse G, Hopkins R, Bowen JM, De Rose G, Novick T, Tarride JE, et al. A cost-effectiveness model comparing endovascular repair to open surgical repair of abdominal aortic aneurysms in Canada. Value Health. 2008;12(2):245–252
   • View In Article
   • Abstract
   • Full-Text PDF (175 KB)
   • CrossRef
3. Alric P, Hinchliffe RJ, Wenham PW, Whitaker SC, Chuter TA, Hopkinson BR. Lessons learned from the long-term follow-up of a first-generation aortic stent graft. J Vasc Surg. 2003;37:367–373
   • View In Article
   • Abstract
   • Full-Text PDF (97 KB)
   • CrossRef
4. Brenner DJ, Hall EJ. Computed tomography – an increasing source of radiation exposure. N Engl J Med. 2007;357:2277–2284
   • View In Article
   • CrossRef
5. Solomon R, DuMouchel W. Contrast media and nephropathy: findings from systematic analysis and food and drug administration reports of adverse effects. Invest Radiol. 2006;41:651–660
   • View In Article
   • MEDLINE
   • CrossRef
6. Noll RE, Tonnessen BH, Mannava K, Money SR, Sternbergh WC. Long-term postplacement costs after endovascular aneurysm repair. J Vasc Surg. 2007;46(1):9–15
   • View In Article
   • Abstract
   • Full Text
   • Full-Text PDF (265 KB)
   • CrossRef
7. Prinssen M, Wixon CL, Buskens E, Blankensteijn JD. Surveillance after endovascular aneurysm repair: diagnostics, complications, and associated costs. Ann Vasc Surg. 2004;18(4):421–427
   • View In Article
   • Abstract
   • Full Text
   • Full-Text PDF (583 KB)
   • CrossRef
8. Sharma P, Kyriakides C. Surveillance of patients post-endovascular aneurysm repair. Postgrad Med J. 2007;83:750–753
   • View In Article
   • CrossRef
9. May J, White GH, Stephen MS, Harris JP. Rupture of abdominal aortic aneurysm: concurrent comparison of outcome of those occurring after endovascular repair versus those occurring without previous treatment in an 11-year single-center experience. J Vasc Surg. 2004;40:860–866
   • View In Article
   • Abstract
   • Full Text
   • Full-Text PDF (240 KB)
   • CrossRef
10. Black SA, Carrell TW, Bell RE, Waltham M, Reidy J, Taylor P. Long-term surveillance with computed tomography after endovascular repair may not be justified. Br J Surg. 2009;96(11):1280–1283
    • View In Article
    • CrossRef
11. Verhoeven EL, Tielliu IFJ, Prins TR, Zeebregts CJAM, van Andringa de Kempenaer MG, Cina CS, et al. Frequency and outcome of re-interventions after endovascular repair for abdominal aortic aneurysm: a prospective cohort study. Eur J Vasc Endovasc Surg. 2004;28:357–364
    • View In Article
12. Karthikesalingam A, Holt PJ, Hinchliffe RJ, Nordon IM, Loftus IM, Thompson MM. Frequency of re-intervention after endovascular aneurysm repair: can post-operative surveillance be curtailed? Br J Surg, in press.
    • View In Article
13. Coppi G, Silingardi R, Saitta G, Gennai S. Single-center experience with the Talent LPS endograft in patients with at least 5 years of follow-up. J Endovasc Ther. 2008;15(1):23–32
    • View In Article
    • CrossRef
14. Peppelenbosch N, Buth J, Harris PL, Van Marrewijk CJ, Fransen G. Diameter of abdominal aortic aneurysm and outcome of endovascular aneurysm repair: does size matter? A report from EUROSTAR. J Vasc Surg. 2004;39(2):288–297
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (207 KB)
    • CrossRef
15. Boult M, Babidge W, Maddem G, Barnes M, Fitridge R. Predictors of success following endovascular aneurysm repair. Eur J Vasc Endovasc Surg. 2006;31:123–129
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (145 KB)
    • CrossRef
16. Van Marrewijk CJ, Fransen G, Laheij RJ, Harris PL, Buth J. Is a type II endoleak after EVAR a harbinger of risk? Causes and outcome of open conversion and aneurysm rupture during follow-up. Eur J Vasc Endovasc Surg. 2004;27(2):128–137
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (164 KB)
    • CrossRef
17. Rumball-Smith A, Wright IA, Buckenham TM. Strut failure in the body of the Zenith abdominal endoprosthesis. Eur J Vasc Endovasc Surg. 2006;32:136–139
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (90 KB)
    • CrossRef
18. Tuerff SN, Rockman CB, Lamparello PJ, Adelman MA, Jacobowitz GR, Gagne PJ, et al. Are type II (branch vessel) endoleaks really benign?. Ann Vasc Surg. 2002;16:50–54
    • View In Article
    • Abstract
    • Full-Text PDF (426 KB)
    • CrossRef
19. Eksandari MK, Yao JST, Pearce WH, Rutherford RB, Veith FJ, Harris PL, et al. Surveillance after endoluminal repair of abdominal aortic aneurysms. Cardiovasc Surg. 2001;9(5):469–471
    • View In Article
    • MEDLINE
    • CrossRef
20. Bargellini I, Cioni R, Napoli V, Petruzzi P, Vignali C, Cicorelli A, et al. Ultrasonographic surveillance with selective CTA after endovascular repair of abdominal aortic aneurysm. J Endovasc Ther. 2009;16:93–104
    • View In Article
    • CrossRef
21. Go MR, Barbato JE, Rhee RY, Makaroun MS. What is the clinical utility of a 6-month computed tomography in the follow-up of endovascular aneurysm repair patients?. J Vasc Surg. 2008;47(6):1181–1186[discussion 1186–7]
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (362 KB)
    • CrossRef
22. Waasdorp E, Van Herwaarden JA, van de Mortel RH, Moll FL, de Vries JP. Early computed tomographic angiography after endovascular repair: worthwhile or worthless?. Vascular. 2008;16(5):253–257
    • View In Article
    • CrossRef
23. AbuRahma AF, Welch CA, Mullins BB, Dyer B. Computed tomography versus color duplex ultrasound for surveillance of abdominal aortic stent-grafts. J Endovasc Ther. 2005;12(5):568–573
    • View In Article
    • MEDLINE
    • CrossRef
24. Rayt HS, Sandford RM, Salem M, Bown MJ, London NJ, Sayers RD. Conservative management of type 2 endoleaks is not associated with increased risk of aneurysm rupture. Eur J Vasc Endovasc Surg. 2009;38(6):718–723
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (130 KB)
    • CrossRef
25. Jones JE, Atkins MD, Brewster DC, Chung TK, Kwolek CJ, Lamuraglia GM, et al. Persistent type 2 endoleak after endovascular repair of abdominal aortic aneurysm is associated with adverse late outcomes. J Vasc Surg. 2007;46(1):1–8
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (391 KB)
    • CrossRef
26. Brewster DC, Jones JE, Chung TK, Lamuraglia GM, Kwolek CJ, Watkins MT, et al. Long-term outcomes after endovascular abdominal aortic aneurysm repair: the first decade. Ann Surg. 2006;244(3):426–438
    • View In Article
    • MEDLINE
27. Pitoulias GA, Schulte S, Donas KP, Horsch S. Secondary endovascular and conversion procedures for failed endovascular abdominal aortic aneurysm repair: can we still be optimistic?. Vascular. 2009;17(1):15–22
    • View In Article
    • CrossRef
28. Lifeline registry of endovascular aneurysm repair: registry data report. J Vasc Surg. 2005;42(1):1–10
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (746 KB)
    • CrossRef
29. Woody JD, Makaroun MS. Endovascular graft limb occlusion. Semin Vasc Surg. 2004;17(4):262–267
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (261 KB)
    • CrossRef
30. Biasi L, Ali T, Ratnam L, Morgan R, Loftus IM, Thompson MM. DynaCT improves intra-operative quality control during endovascular abdominal aortic aneurysm repair. J Vasc Surg. 2009;49(2):288–295
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (525 KB)
    • CrossRef
31. Schlosser FJV, Gusberg RJ, Dardik A, Lin PH, Verhagen HJ, Moll FL, et al. Aneurysm rupture after EVAR: can the ultimate failure be predicted. Eur J Vasc Endovasc Surg. 2009;37(1):15–22
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (349 KB)
    • CrossRef
32. Moore WS, Matsumura JS, Makaroun MS, Katzen BT, Deaton DH, Decker M, et al. Five-year interim comparison of the Guidant bifurcated endograft with open repair of abdominal aortic aneurysm. J Vasc Surg. 2003;38(1):46–55
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (293 KB)
    • CrossRef
33. Vogel TR, Symons RG, Flum DR. Longitudinal outcomes after endovascular repair of abdominal aortic aneurysms. Vasc Endovascular Surg. 2008;42(5):412–419
    • View In Article
    • CrossRef
34. Dias NV, Riva L, Ivancev K, Resch T, Sonesson B, Malina M. Is there a benefit of frequent CT follow-up after EVAR?. Eur J Vasc Endovasc Surg. 2009;37(4):425–430
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (204 KB)
    • CrossRef
35. Sternbergh WC, Greenberg RK, Chuter TA, Tonnessen BH. Redefining postoperative surveillance after endovascular aneurysm repair: recommendations based on 5-year follow-up in the US Zenith multicenter trial. J Vasc Surg. 2008;48(2):278–284[discussion 284–5]
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (334 KB)
    • CrossRef
36. Leurs LJ, Kievit J, Dagnelie PC, Nelemans PJ, Buth J. Influence of infrarenal neck length on outcome of endovascular abdominal aortic aneurysm repair. J Endovasc Ther. 2006;13:640–648
    • View In Article
    • MEDLINE
    • CrossRef
37. Aburahma AF, Campbell J, Stone PA, Nanjundappa A, Jain A, Dean LS, et al. The correlation of aortic neck length to early and late outcomes in endovascular aneurysm repair patients. J Vasc Surg. 2009;
    • View In Article
38. Sternbergh WC, Carter G, York JW, Yoselevitz M, Money SR. Aortic neck angulation predicts adverse outcome with endovascular abdominal aortic aneurysm repair. J Vasc Surg. 2002;35(3):482–486
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (66 KB)
    • CrossRef
39. Stanley BM, Semmens JB, Mai Q, Goodman MA, Hartley DE, Wilkinson C, et al. Evaluation of patient selection guidelines for endoluminal AAA repair with the Zenith stent-graft: the Australasian experience. J Endovasc Ther. 2001;8(5):457–464
    • View In Article
    • MEDLINE
    • CrossRef
40. Laheij RJ, van Marrewijk CJ, Buth J, Harris PL. The influence of team experience on outcomes of endovascular stenting of abdominal aortic aneurysms. Eur J Vasc Endovasc Surg. 2002;24(2):128–133
    • View In Article
    • Abstract
    • Full-Text PDF (92 KB)
    • CrossRef