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Early versus late experience in fenestrated endovascular repair for abdominal aortic aneurysm
From the Society for Vascular Surgery
Early versus late experience in fenestrated endovascular repair for abdominal aortic aneurysm Magnus Sveinsson, MD,a Jonathan Sobocinski, MD, PhD,b Timothy Resch, MD, PhD,a Björn Sonesson, MD, PhD,a Nuno Dias, MD, PhD,a Stéphan Haulon, MD, PhD,b and Thorarinn Kristmundsson, MD, PhD,a Malmö, Sweden; and Lille, France Objective: The objective of this study was to evaluate operative results and 1-year outcomes in early vs late experience after fenestrated endovascular aortic repair. Methods: All patients treated in Malmö, Sweden, and in Lille, France, with fenestrated endovascular repair for abdominal aortic aneurysm were prospectively enrolled in a computerized database. Early experience was defined as the first 50 patients treated at each center. Data from early and late experience were retrospectively analyzed and compared for differences in operative results and 1-year outcomes. Results: Early experience covered 4.7 years in Malmö and 4.5 years in Lille; late experience covered 5.6 years in Malmö and 3.7 years in Lille. A total of 288 patients were included. In the later phase, stent graft configuration was more complex because of increased number of fenestrations/scallops incorporated in the graft design (2.7 6 0.8 vs 3.2 6 0.7; P < .001). Despite this, volume of contrast material and radiation time decreased by 27% and 20%, respectively, whereas procedure time remained unchanged. At 1 year, a trend toward decreasing abdominal aortic aneurysm diameter was observed in the late group, but no differences were found in mortality, endoleaks, or target vessel patency between the groups. Conclusions: With increasing experience, fenestrated endovascular aneurysm repair design has become more complicated, with more visceral vessels targeted for better proximal seal, while operative risk still remains low. Simultaneously, radiation time and volume of contrast material have been reduced, with possible long-term benefits for the patient. (J Vasc Surg 2015;61:895-901.)
The suitability of standard infrarenal stent grafts in the treatment of infrarenal aortic aneurysms is primarily affected by poor proximal and distal sealing zones and limited iliac access.1 Access issues are being overcome with low-profile delivery systems as well as adjunctive operative procedures, and distal sealing zone issues can be dealt with by a number of techniques with good outcome and limited long-term consequences for the patients.2-5 The proximal sealing zone, however, remains a significant problem for both short- and long-term outcome after endovascular aneurysm repair (EVAR).6,7 Not only does it decrease the applicability of standard EVAR, but when it is ignored, it can lead to early and late failure, such as migration, endoleak, and aneurysm rupture.8 To overcome the issue of poor infrarenal sealing zone limiting standard EVAR, fenestrated endografts (FEVAR) From the Vascular Center, Skåne University Hospital, Malmöa; and the Aortic Centre, Hôpital Cardiologique, CHRU Lille.b Author conflict of interest: T.R.: patents, consulting fees, speaker’s bureau Cook Medical, Inc. N.D.: proctoring, speaker’s bureau Cook Medical Inc. S.H.: patents, consulting fees, speaker’s bureau Cook Medical Inc. Presented as an abstract at the International Forum of the 2013 Vascular Annual Meeting of the Society for Vascular Surgery, San Francisco, Calif, May 30-June1, 2013. Reprint requests: Magnus Sveinsson, MD, Vascular Center, Skåne University Hospital, 205 02 Malmö, Sweden (e-mail: magnus.sveinsson@ skane.se). The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest. 0741-5214 Copyright Ó 2015 by the Society for Vascular Surgery. Published by Elsevier Inc. http://dx.doi.org/10.1016/j.jvs.2014.11.007
were introduced in the late 1990s.9 The fenestrations allow the stent graft to be placed across the visceral segment of the aorta while preserving flow to the visceral arteries. Thus, the aortic repair is extended proximally to a healthy aortic segment where a stent graft can seal securely.10,11 Fenestrated stent grafting introduces a level of complexity compared with infrarenal EVAR with regard to both planning and implantation. Initially, the perception was that the use of more than two renal fenestrations and a scallop for the superior mesenteric artery (SMA) made the procedure vastly more complex and that the use of contrast material and radiation dose became prohibitive. Over time, a belief in reaching healthy, paralleled wall aorta for seal, in combination with improved planning and implantation skills, led us to more liberal use of additional fenestration for the SMA, thus placing the graft more proximally. The purpose of the current study was to evaluate our experience in fenestrated stent grafting and its impact on stent graft design and short-term outcome. METHODS All patients treated with commercially available, custom-made FEVAR devices for juxtarenal and pararenal aortic aneurysm in Malmö, Sweden, and in Lille, France, from 2002 to 2011 were prospectively enrolled in a computerized database. The cutoff number of 50 patients between the early and late groups was determined by the fact that one center has previously published experience from their first 54 FEVAR patients. In addition, the recommended experience to achieve competence in fenestrated 895
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stent grafting is considered to be around 50 cases. The early and late groups even represent the first 4.6 years and last 4.7 years of our experience, respectively. In Malmö, all procedures were performed with a Siemens Artis Zee fixed imaging system (Siemens Medical Solutions, Erlangen, Germany). In Lille, all the procedures were performed with OEC 9900 Elite MD mobile C-arm (GE Healthcare, Buc, France). During the study period, protocols for intraoperative imaging and contrast material use remained virtually unchanged. However, a successive change to the use of low-dose fluoroscopy was introduced as imaging software was updated over time. For the purpose of this study, patients who underwent FEVAR for thoracoabdominal disease and patients with <1 year of follow-up were excluded from the current analysis. Workup consisted of clinical examination and high-resolution spiral computed tomography (CT) scans, which were reconstructed in a vascular three-dimensional workstation (www.terarecon.com). The Zenith device (cookmedical.com) formed the foundation of the fenestrated graft in all cases. The device has been described previously in detail. In short, the device consists of three main components. A proximal tubular graft is planned with fenestrations for the target vessels (TVs) that are to be included in the repair. Fenestrations can be of three principal types: small (6 6 mm or 6 8 mm) without crossing stent struts, large (8 to 10 mm in diameter) with crossing stent struts, or scallop (6 to 12 mm deep and 10 mm wide) at the top of the first covered stent. By moving the fenestrations distally on the graft, one can also position the large fenestrations so that they have no crossing struts. This is preferable if one intends to stent the TV it engages. Small fenestrations and “strut-free” large fenestrations are routinely stented with balloon-expandable stents, whereas scallops are most often left stent free. After implantation of the fenestrated stent graft component and the TV stents, the procedure is completed with a bifurcated distal extension and an iliac leg extension. Care is taken to provide sufficient overlap between the various components. The only restrictions in device design during the study period were manufacturing constraints stating requirement for fenestration spacing circumferentially and longitudinally. This design range differs significantly from the Cook Zenith fenestrated device currently approved in the United States, for which a maximum of three fenestrations and a maximum of two of the same type are allowed. Intraoperative variables such as contrast material use, fluoroscopy time, and duration of surgery were considered surrogate markers for surgical complexity and were thus analyzed and compared between the two cohorts. Follow-up consisted of postoperative clinical examination within the first month as well as CT scans and plain abdominal films after 1 month and 1 year in Malmö and 6 months and 1 year in Lille. Deaths were verified through national mortality registers, and medical records were obtained for further analysis when aneurysm-related death was suspected. Aneurysm-related death was defined as all deaths occurring within 30 days from the initial procedure
Table I. Patient demographics
Male Age, years AAA diameter, mm Smoking Hypertension Diabetes Coronary heart disease COPD Renal failure (GFR <60) CVI
Early, %
Late, %
P
91 72 6 7 58.9 6 10 82 59 18 49 39 26 14
87 72 6 7 59.3 6 10 79 78 17 47 37 14 11
NS NS NS NS <.01 NS NS NS .05 NS
AAA, Abdominal aortic aneurysm; COPD, chronic obstructive pulmonary disease; CVI, cerebrovascular insult; GFR, glomerular filtration rate; NS, not significant. Smoking, hypertension, CVI, diabetes, and COPD are defined according to the Society for Vascular Surgery/International Society for Cardiovascular Surgery reporting standards. Early and late denote early and late groups.
as well as late deaths associated with stent graft complications. Endoleaks and changes in aneurysm diameter during follow-up were registered. Aneurysm diameter changes were considered significant when $5 mm. For the purpose of this study, early experience was defined as the first 50 patients treated at each center. Data from early and late experience were compared for differences in operative results (30 days) and 1-year outcomes. All patients gave informed consent for the procedures and follow-up. Institutional Review Board approval was waived as all patients were treated under standard clinical practice. Statistics. One-way analysis of variance was used for continuous data. The c2 test was used for percentage comparisons. Statistical analysis was done in SPSS version 22.0 (SPSS Inc, Chicago, Ill; www.spss.com). Measurements are presented as mean 6 standard deviation. P < .05 was considered significant. RESULTS A total of 288 patients were included in this study. Early experience (n ¼ 100) covered 4.7 years in Malmö and 4.5 years in Lille (mean, 4.6 years); late experience (n ¼ 188) covered 5.6 years in Malmö and 3.7 years in Lille (mean, 4.7 years). Median follow-up for the groups was 11.5 6 2 vs 11.7 6 2 months, respectively. Patient characteristics and comorbidities are given in Table I. In the later experience, stent grafts had a higher number of fenestrations/scallops incorporated in the graft design (2.7 6 0.8 vs 3.2 6 0.7; P < .001), with 40% of patients receiving grafts with three or more fenestrations compared with 8% in the early phase (Table II). Despite the increasing number of TVs over time, technical success improved from 92% to 98% between the two periods, in which a single TV catheterization failure occurred in only four patients in the later phase of the study. In the early period, three renals and three SMAs occluded during follow-up. In one case, the renal artery was sacrificed intraoperatively to seal a type I endoleak. In all other cases, the
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Table II. Stent graft configuration in the study period Configuration 1 fenestration (renal) 2 fenestrations (renal þ 2 fenestrations (renal þ SMA scallop 3 fenestrations (renal þ SMA) 3 fenestrations (renal þ SMA) þ CA scallop 4 fenestrations (renal þ SMA þ CA)
Early, %
Late, %
renal) renal) þ
2 (n ¼ 2) 22 (n ¼ 22) 66 (n ¼ 66)
0 (n ¼ 0) 3 (n ¼ 6) 55 (n ¼ 103)
renal þ
2 (n ¼ 2)
2 (n ¼ 4)
renal þ
4 (n ¼ 4)
28 (n ¼ 53)
renal þ
4 (n ¼ 4)
12 (n ¼ 22)
CA, Celiac trunk; SMA, superior mesenteric artery. There was a trend toward more fenestrations (with or without scallops) in the later phase of the study. Early and late denote early and late groups.
patients were asymptomatic and the occlusions were detected on routine follow-up. In the later phase, seven renals and one SMA occluded. In one case, the fenestrated component migrated distally, crushing stents in both renal arteries and in the SMA, which rendered the patient dialysis dependent. All other renal occlusions were asymptomatic. Whereas procedure time remained unchanged, contrast material volume and radiation time decreased significantly by 27% and 20%, respectively (Figs 1 and 2). More important, there was a 20% reduction in the iodine load for each patient (54 g vs 43 g; P ¼ .004), partly as a result of more frequent use of lower strength contrast media (100140 mg iodine/mL). Despite the possible long-term benefit on renal function, there were no statistically significant differences in plasma creatinine levels between the early and late groups in preoperative measurements (109 6 38 vs 109 6 81 mmol/L) or at hospital discharge (151 6 86 vs 129 6 77 mmol/L). Operative mortality occurred in two patients (2%) in the early phase and in four patients (2.1%) in the later phase. All deaths except one were associated with technical causes: iliac artery rupture in poor iliac access (n ¼ 1), aneurysm rupture during the procedure (n ¼ 1), renal artery perforation with massive retroperitoneal bleeding (n ¼ 1), mesenteric embolization with multiorgan failure (n ¼ 2), and postoperative myocardial infarction (n ¼ 1). A summary of operative outcomes is given in Table III. At 1 year, abdominal aortic aneurysm diameter decreased $5 mm in 54% of patients in the early group and in 62% of patients in the late group (P ¼ .3) (Fig 3). Similar results for aneurysm expansion were 5% and 2%, respectively. Of the five expanding aneurysms, two were found to have type I endoleak (both in the early group) and one a type II endoleak (late group) at 1-year followup. No differences were found in reintervention rates or endoleaks at 1-year follow-up (Table IV). DISCUSSION Randomized trials have shown a marked benefit of EVAR compared with open repair with respect to early operative morbidity and mortality.12-14 Despite this, EVAR carries device-specific limitations that can predispose
Fig 1. A scattergram showing the volume of contrast material used during procedures, illustrating the reduction of volumes with growing experience. Dates are in the form of yy-mm-dd.
Fig 2. A scattergram showing the reduction in intraoperative radiation time with more experience. Dates are in the form of yy-mm-dd.
patients to further hospital admissions and secondary interventions. Among these is the risk of incomplete sealing in the aneurysm neck, allowing continuous repressurization of the aneurysm sac with risk of late rupture. Recent reports on anatomic suitability for EVAR indicate that only half of patients fulfill the stent graft manufacturer’s instructions for use for safe and durable treatment.11 EVAR performed in a setting outside the instructions for use has been shown to increase the risk for intraoperative failure, postoperative complications, and late aneurysm expansion.15,16 During FEVAR, the stent graft is moved more proximally to the level of the visceral arteries. By doing so, blood flow to vital organs is secured through fenestrations in the graft fabric while achieving a more proximal seal (Fig 4). In contrast to standard EVAR systems, a FEVAR device is custom-made for each individual patient based on accurate
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Table III. Operative results
Procedure time, minutes Fluoroscopy time, minutes Contrast volume, mL Iodine load, g TVs Stented TVs 30-day mortality
Table IV. Results at 1-year follow-up Early
Late
P
276 6 91 84 6 41 254 6 120 54 6 25 2.7 6 0.8 64% 2.0%
280 6 133 68 6 63 184 6 90 43 6 18 3.2 6 0.7 77% 2.1%
NS .05 <.05 .004 <.01 <.01 NS
NS, Not significant; TVs, target vessels. Early and late denote early and late groups.
Fig 3. A scattergram of change in aneurysm size at 1-year follow-up. Measurements are in millimeters. AAA, Abdominal aortic aneurysm.
measurements on preoperative CT angiography reconstructions and is therefore not available in acute situations. Manufacturing time is 4 to 6 weeks. In addition, the procedure is technically challenging, and a multitude of sheaths, catheters, and wires are used for TV catheterization. This results in longer operation time, more radiation and contrast material exposure, and a procedure-specific spectrum of complications.17-20 The Zenith fenestrated abdominal aortic aneurysm endovascular graft has been commercially available in the European Union since late 2005 and was approved by the Food and Drug Administration in the United States in April 2012.21 During the development phase, our centers had the opportunity to use the device on selected patients along with a few other centers. The first procedure was performed in Malmö in 2002 and in Lille in 2004. Since then, the volume of treatments has gradually increased, and FEVAR is now considered the treatment of choice for juxtarenal aneurysms in both centers, with promising early and intermediate results.17 In our early experience, a limiting factor was the technical challenge of TV catheterization, resulting in extended operation time, high radiation dose, and large amounts of
Type I endoleak Type II endoleak Reinterventions Decreasing AAA diameter Expanding AAA diameter AAA mortality Overall mortality
Early, %
Late, %
P
1.2 14 8 54 5 3.0 4
1.0 10 12 61 2 3.2 7
NS NS NS NS NS NS NS
AAA, Abdominal aortic aneurysm; NS, not significant. Early and late denote early and late groups.
contrast media used in comparison to standard infrarenal EVAR.18-20,22 From a planning perspective, including fenestrations for the renal arteries only and placing a scallop for the SMA seem to be relatively reproducible.23 Because only the renal fenestrations are stented, only these need to be placed accurately to their TV. In the early experience, the SMA scallop was used merely as a “safety” and its position largely ignored during implantation. It was assumed that if the plan was correct, the position of the SMA scallop would be correct. Experience showed, however, that unstented SMA scallops were at an increased risk of postoperative occlusion because of a partial shuttering effect.17,24,25 Accurate determination of the rotational position of an SMA scallop by intraoperative angiography is quite difficult. This insight gradually led to the practice of routinely stenting SMA scallops and later replacing the scallop with a stented, large “strut-free” fenestration. As we became more comfortable with both planning and delivery, the addition of an extra SMA fenestration became more routine. The initial fear that this dramatically increased the risk of the procedure was not reflected in clinical outcomes. It does, however, add an extra TV to catheterize and stent. Our results show that the technical success rate remains high despite the increased number of fenestrations on the graft and the increased number of stented TVs. The total operative time remains unchanged despite the increased complexity of the fenestrated cuff. This might reflect an increased skill in catheterization and stenting of the TV but also that this part of the total procedure is relatively small. The additional time to catheterize and stent an extra TV is offset by the large number of other steps involved in a FEVAR procedure. The catheterization and stenting of the TV is, however, the part that is most dependent on fluoroscopy for guidance, and this was also reduced in the second part of the study. The total amount of contrast material used was reduced over time. Initially, repeated runs of 10 to 20 mL of contrast material were often used in positioning the fenestrated component in relation to the TV. This probably reflected both a lack of confidence in the device planning and a lesser ability to estimate the way the fenestrated device conformed in vivo as opposed to the preoperative imaging. In the later phase, particularly when facing tortuosity in the sealing region, we adopted the practice of precatheterizing one or several
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Fig 4. A, Preoperative computed tomography (CT) scan in anterior-posterior projection showing juxtarenal aneurysm but normal configuration suprarenal aorta. B, In lateral projection, a bulge is seen posterior to the origin of the superior mesenteric artery (SMA), indicating suprarenal extension of disease. C, Completion angiography after implantation of a four-fenestrated stent graft. D, CT angiography at 1 month postoperatively with excluded aneurysm and all visceral arteries stented and patent.
of the TVs to guide device positioning. This reduces the need for repeated runs of contrast material during device deployment as the position can be estimated with help of the catheters placed in the TV. In addition to reducing the contrast material volume, we now routinely use lower strength contrast media (100-140 mgI/mL) to reduce the contrast material load. In the years after this study, we have taken this a step further by using intraoperative imaging fusion techniques. This allows us to mark the TV on the basis of the preoperative CT angiography imaging, thus reducing the need for contrast material intraoperatively even further.19 In parallel to this more selective use of radiation and contrast material, other technical developments have been made that might influence and perhaps reduce the time
of implantation. Knowledge of which catheters and sheaths that perform in a specific manner has made the procedures easier. The technique of catheterizing and stenting a visceral vessel in the context of FEVAR is vastly different from that in treating occlusive disease, for example, and these skills are improved with experience. Despite the increase in numbers of stented TVs, the difference in endoleaks, sac shrinkage, and survival is not significant at 1-year follow-up. Previously published longterm outcomes from the initial cases indicate that durability up to 5 years is excellent in this cohort. The trend of incorporating a higher number of TVs can thus be questioned. It is possible that radiation time and contrast material volumes could be reduced further by avoiding the tendency to incorporate more TVs. Only long-term durability data will
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reveal if the addition of more fenestrations and a more proximal graft placement will also lead to fewer longterm failures. Long-term follow-up is limited to a few early adopting centers and seems to suggest that type I endoleaks are more common in patients with renal fenestrations only (personal communication, Tara Mastracci, Cleveland Clinic Foundation, Ohio). There are a number of limitations to this study. The retrospective nature implies that the patients are not exactly matched with regard to aneurysm anatomy, and this might affect the analysis. The exclusion of patients with thoracoabdominal aortic aneurysm partially compensates for this, but the number of patients with necks too short for standard EVAR vs those with true juxtarenal aneurysm is unknown and would require a complete re-review of the preoperative imaging, and this was outside the scope of the current study. Furthermore, changes in planning and operative management often come as small incremental improvements. This is similar to the overall development of endovascular procedures. For composite, complex endovascular procedures such as implantation of fenestrated stent grafts, the multitude of steps involved in the procedure in addition to the multitude of endovascular tools used make it virtually impossible to pinpoint when in time a significant change occurs. It is therefore difficult to exactly define a learning curve cutoff, and this makes the interpretation more difficult. CONCLUSIONS With increasing experience and patient selection, FEVAR planning and design have changed, with more visceral vessels targeted for better proximal seal while operative risk remains low. Simultaneously, radiation time, contrast material volume, and iodine load have been reduced, with possible long-term benefits for the patient. Long-term follow-up is needed to evaluate the effect of these changes on FEVAR durability. AUTHOR CONTRIBUTIONS Conception and design: TR, SH Analysis and interpretation: MS, JS, TR, BS, ND, SH, TK Data collection: MS, JS, TK Writing the article: MS, TR, TK Critical revision of the article: MS, JS, TR, BS, ND, SH, TK Final approval of the article: MS, JS, TR, BS, ND, SH, TK Statistical analysis: TK Obtained funding: Not applicable Overall responsibility: TK REFERENCES 1. Tambyraja AL, Fishwick NG, Bown MJ, Nasim A, McCarthy MJ, Sayers RD. Fenestrated aortic endografts for juxtarenal aortic aneurysm: medium term outcomes. Eur J Vasc Endovasc Surg 2011;42:54-8. 2. Hinchliffe RJ, Ivancev K, Sonesson B, Malina M. “Paving and cracking”: an endovascular technique to facilitate the introduction of aortic stent-grafts through stenosed iliac arteries. J Endovasc Ther 2007;14:630-3.
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3. Peterson BG. Conduits and endoconduits, percutaneous access. J Vasc Surg 2010;52(Suppl):60S-4S. 4. Peterson BG, Matsumura JS. Internal endoconduit: an innovative technique to address unfavorable iliac artery anatomy encountered during thoracic endovascular aortic repair. J Vasc Surg 2008;47: 441-5. 5. Rahimi SA, O’Donnell PL, Graham AM. Endovascular repair of abdominal aortic aneurysm with extreme iliac artery tortuosity. Vasc Endovascular Surg 2010;44:472-4. 6. Carpenter JP, Baum RA, Barker CF, Golden MA, Mitchell ME, Velazquez OC, et al. Impact of exclusion criteria on patient selection for endovascular abdominal aortic aneurysm repair. J Vasc Surg 2001;34:1050-4. 7. Moritz JD, Rotermund S, Keating DP, Oestmann JW. Infrarenal abdominal aortic aneurysms: implications of CT evaluation of size and configuration for placement of endovascular aortic grafts. Radiology 1996;198:463-6. 8. 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;50:738-48. 9. Park JH, Chung JW, Choo IW, Kim SJ, Lee JY, Han MC. Fenestrated stent-grafts for preserving visceral arterial branches in the treatment of abdominal aortic aneurysms: preliminary experience. J Vasc Interv Radiol 1996;7:819-23. 10. Kristmundsson T, Sonesson B, Malina M, Bjorses K, Dias N, Resch T. Fenestrated endovascular repair for juxtarenal aortic pathology. J Vasc Surg 2009;49:568-74; discussion: 574-5. 11. Canning C, Martin Z, Colgan MP, Abdulrahim O, McCafferty M, Fitzpatrick J, et al. Fenestrated endovascular repair of complex aortic aneurysms. Ir J Med Sci 2014 Mar 6. [Epub ahead of print]. 12. Chahwan S, Comerota AJ, Pigott JP, Scheuermann BW, Burrow J, Wojnarowski D. Elective treatment of abdominal aortic aneurysm with endovascular or open repair: the first decade. J Vasc Surg 2007;45: 258-62; discussion: 262. 13. Prinssen M, Verhoeven EL, Buth J, Cuypers PW, van Sambeek MR, Balm R, et al. A randomized trial comparing conventional and endovascular repair of abdominal aortic aneurysms. N Engl J Med 2004;351:1607-18. 14. United Kingdom EVAR Trial Investigators, Greenhalgh RM, Brown LC, Powell JT, Thompson SG, Epstein D, Sculpher MJ. Endovascular versus open repair of abdominal aortic aneurysm. N Engl J Med 2010;362:1863-71. 15. Schanzer A, Greenberg RK, Hevelone N, Robinson WP, Eslami MH, Goldberg RJ, et al. Predictors of abdominal aortic aneurysm sac enlargement after endovascular repair. Circulation 2011;123:2848-55. 16. 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;8:457-64. 17. Kristmundsson T, Sonesson B, Dias N, Tornqvist P, Malina M, Resch T. Outcomes of fenestrated endovascular repair of juxtarenal aortic aneurysm. J Vasc Surg 2014;59:115-20. 18. Mohapatra A, Greenberg RK, Mastracci TM, Eagleton MJ, Thornsberry B. Radiation exposure to operating room personnel and patients during endovascular procedures. J Vasc Surg 2013;58:702-9. 19. Maurel B, Hertault A, Sobocinski J, Le Roux M, Martin Gonzalez T, Azzaoui R, et al. Techniques to reduce radiation and contrast volume during EVAR. J Cardiovasc Surg 2014;55(Suppl 1):123-31. 20. Maurel B, Sobocinski J, Perini P, Guillou M, Midulla M, Azzaoui R, et al. Evaluation of radiation during EVAR performed on a mobile Carm. Eur J Vasc Endovasc Surg 2012;43:16-21. 21. Unno N, Yamamoto N, Higashiura W, Suzuki M, Mano Y, Sano M, et al. Early experience with fenestrated stent grafts for treatment of juxtarenal aortic aneurysm. Ann Vasc Dis 2013;6:642-50. 22. Panuccio G, Greenberg RK, Wunderle K, Mastracci TM, Eagleton MG, Davros W. Comparison of indirect radiation dose estimates with directly measured radiation dose for patients and operators during complex endovascular procedures. J Vasc Surg 2011;53: 885-94.e1; discussion: 894.
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23. Malkawi AH, Resch TA, Bown MJ, Manning BJ, Poloniecki JD, Nordon IM, et al. Sizing fenestrated aortic stent-grafts. Eur J Vasc Endovasc Surg 2011;41:311-6. 24. England A, Garcia-Finana M, Fisher RK, Naik JB, Vallabhaneni SR, Brennan JA, et al. Migration of fenestrated aortic stent grafts. J Vasc Surg 2013;57:1543-52.
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25. Verhoeven EL, Vourliotakis G, Bos WT, Tielliu IF, Zeebregts CJ, Prins TR, et al. Fenestrated stent grafting for short-necked and juxtarenal abdominal aortic aneurysm: an 8-year single-centre experience. Eur J Vasc Endovasc Surg 2010;39:529-36. Submitted Aug 12, 2014; accepted Nov 4, 2014.
Early versus late experience in fenestrated endovascular repair for abdominal aortic aneurysm Magnus Sveinsson, MD,a Jonathan Sobocinski, MD, PhD,b Timothy Resch, MD, PhD,a Björn Sonesson, MD, PhD,a Nuno Dias, MD, PhD,a Stéphan Haulon, MD, PhD,b and Thorarinn Kristmundsson, MD, PhD,a Malmö, Sweden; and Lille, France Objective: The objective of this study was to evaluate operative results and 1-year outcomes in early vs late experience after fenestrated endovascular aortic repair. Methods: All patients treated in Malmö, Sweden, and in Lille, France, with fenestrated endovascular repair for abdominal aortic aneurysm were prospectively enrolled in a computerized database. Early experience was defined as the first 50 patients treated at each center. Data from early and late experience were retrospectively analyzed and compared for differences in operative results and 1-year outcomes. Results: Early experience covered 4.7 years in Malmö and 4.5 years in Lille; late experience covered 5.6 years in Malmö and 3.7 years in Lille. A total of 288 patients were included. In the later phase, stent graft configuration was more complex because of increased number of fenestrations/scallops incorporated in the graft design (2.7 6 0.8 vs 3.2 6 0.7; P < .001). Despite this, volume of contrast material and radiation time decreased by 27% and 20%, respectively, whereas procedure time remained unchanged. At 1 year, a trend toward decreasing abdominal aortic aneurysm diameter was observed in the late group, but no differences were found in mortality, endoleaks, or target vessel patency between the groups. Conclusions: With increasing experience, fenestrated endovascular aneurysm repair design has become more complicated, with more visceral vessels targeted for better proximal seal, while operative risk still remains low. Simultaneously, radiation time and volume of contrast material have been reduced, with possible long-term benefits for the patient. (J Vasc Surg 2015;61:895-901.)
The suitability of standard infrarenal stent grafts in the treatment of infrarenal aortic aneurysms is primarily affected by poor proximal and distal sealing zones and limited iliac access.1 Access issues are being overcome with low-profile delivery systems as well as adjunctive operative procedures, and distal sealing zone issues can be dealt with by a number of techniques with good outcome and limited long-term consequences for the patients.2-5 The proximal sealing zone, however, remains a significant problem for both short- and long-term outcome after endovascular aneurysm repair (EVAR).6,7 Not only does it decrease the applicability of standard EVAR, but when it is ignored, it can lead to early and late failure, such as migration, endoleak, and aneurysm rupture.8 To overcome the issue of poor infrarenal sealing zone limiting standard EVAR, fenestrated endografts (FEVAR) From the Vascular Center, Skåne University Hospital, Malmöa; and the Aortic Centre, Hôpital Cardiologique, CHRU Lille.b Author conflict of interest: T.R.: patents, consulting fees, speaker’s bureau Cook Medical, Inc. N.D.: proctoring, speaker’s bureau Cook Medical Inc. S.H.: patents, consulting fees, speaker’s bureau Cook Medical Inc. Presented as an abstract at the International Forum of the 2013 Vascular Annual Meeting of the Society for Vascular Surgery, San Francisco, Calif, May 30-June1, 2013. Reprint requests: Magnus Sveinsson, MD, Vascular Center, Skåne University Hospital, 205 02 Malmö, Sweden (e-mail: magnus.sveinsson@ skane.se). The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest. 0741-5214 Copyright Ó 2015 by the Society for Vascular Surgery. Published by Elsevier Inc. http://dx.doi.org/10.1016/j.jvs.2014.11.007
were introduced in the late 1990s.9 The fenestrations allow the stent graft to be placed across the visceral segment of the aorta while preserving flow to the visceral arteries. Thus, the aortic repair is extended proximally to a healthy aortic segment where a stent graft can seal securely.10,11 Fenestrated stent grafting introduces a level of complexity compared with infrarenal EVAR with regard to both planning and implantation. Initially, the perception was that the use of more than two renal fenestrations and a scallop for the superior mesenteric artery (SMA) made the procedure vastly more complex and that the use of contrast material and radiation dose became prohibitive. Over time, a belief in reaching healthy, paralleled wall aorta for seal, in combination with improved planning and implantation skills, led us to more liberal use of additional fenestration for the SMA, thus placing the graft more proximally. The purpose of the current study was to evaluate our experience in fenestrated stent grafting and its impact on stent graft design and short-term outcome. METHODS All patients treated with commercially available, custom-made FEVAR devices for juxtarenal and pararenal aortic aneurysm in Malmö, Sweden, and in Lille, France, from 2002 to 2011 were prospectively enrolled in a computerized database. The cutoff number of 50 patients between the early and late groups was determined by the fact that one center has previously published experience from their first 54 FEVAR patients. In addition, the recommended experience to achieve competence in fenestrated 895
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stent grafting is considered to be around 50 cases. The early and late groups even represent the first 4.6 years and last 4.7 years of our experience, respectively. In Malmö, all procedures were performed with a Siemens Artis Zee fixed imaging system (Siemens Medical Solutions, Erlangen, Germany). In Lille, all the procedures were performed with OEC 9900 Elite MD mobile C-arm (GE Healthcare, Buc, France). During the study period, protocols for intraoperative imaging and contrast material use remained virtually unchanged. However, a successive change to the use of low-dose fluoroscopy was introduced as imaging software was updated over time. For the purpose of this study, patients who underwent FEVAR for thoracoabdominal disease and patients with <1 year of follow-up were excluded from the current analysis. Workup consisted of clinical examination and high-resolution spiral computed tomography (CT) scans, which were reconstructed in a vascular three-dimensional workstation (www.terarecon.com). The Zenith device (cookmedical.com) formed the foundation of the fenestrated graft in all cases. The device has been described previously in detail. In short, the device consists of three main components. A proximal tubular graft is planned with fenestrations for the target vessels (TVs) that are to be included in the repair. Fenestrations can be of three principal types: small (6 6 mm or 6 8 mm) without crossing stent struts, large (8 to 10 mm in diameter) with crossing stent struts, or scallop (6 to 12 mm deep and 10 mm wide) at the top of the first covered stent. By moving the fenestrations distally on the graft, one can also position the large fenestrations so that they have no crossing struts. This is preferable if one intends to stent the TV it engages. Small fenestrations and “strut-free” large fenestrations are routinely stented with balloon-expandable stents, whereas scallops are most often left stent free. After implantation of the fenestrated stent graft component and the TV stents, the procedure is completed with a bifurcated distal extension and an iliac leg extension. Care is taken to provide sufficient overlap between the various components. The only restrictions in device design during the study period were manufacturing constraints stating requirement for fenestration spacing circumferentially and longitudinally. This design range differs significantly from the Cook Zenith fenestrated device currently approved in the United States, for which a maximum of three fenestrations and a maximum of two of the same type are allowed. Intraoperative variables such as contrast material use, fluoroscopy time, and duration of surgery were considered surrogate markers for surgical complexity and were thus analyzed and compared between the two cohorts. Follow-up consisted of postoperative clinical examination within the first month as well as CT scans and plain abdominal films after 1 month and 1 year in Malmö and 6 months and 1 year in Lille. Deaths were verified through national mortality registers, and medical records were obtained for further analysis when aneurysm-related death was suspected. Aneurysm-related death was defined as all deaths occurring within 30 days from the initial procedure
Table I. Patient demographics
Male Age, years AAA diameter, mm Smoking Hypertension Diabetes Coronary heart disease COPD Renal failure (GFR <60) CVI
Early, %
Late, %
P
91 72 6 7 58.9 6 10 82 59 18 49 39 26 14
87 72 6 7 59.3 6 10 79 78 17 47 37 14 11
NS NS NS NS <.01 NS NS NS .05 NS
AAA, Abdominal aortic aneurysm; COPD, chronic obstructive pulmonary disease; CVI, cerebrovascular insult; GFR, glomerular filtration rate; NS, not significant. Smoking, hypertension, CVI, diabetes, and COPD are defined according to the Society for Vascular Surgery/International Society for Cardiovascular Surgery reporting standards. Early and late denote early and late groups.
as well as late deaths associated with stent graft complications. Endoleaks and changes in aneurysm diameter during follow-up were registered. Aneurysm diameter changes were considered significant when $5 mm. For the purpose of this study, early experience was defined as the first 50 patients treated at each center. Data from early and late experience were compared for differences in operative results (30 days) and 1-year outcomes. All patients gave informed consent for the procedures and follow-up. Institutional Review Board approval was waived as all patients were treated under standard clinical practice. Statistics. One-way analysis of variance was used for continuous data. The c2 test was used for percentage comparisons. Statistical analysis was done in SPSS version 22.0 (SPSS Inc, Chicago, Ill; www.spss.com). Measurements are presented as mean 6 standard deviation. P < .05 was considered significant. RESULTS A total of 288 patients were included in this study. Early experience (n ¼ 100) covered 4.7 years in Malmö and 4.5 years in Lille (mean, 4.6 years); late experience (n ¼ 188) covered 5.6 years in Malmö and 3.7 years in Lille (mean, 4.7 years). Median follow-up for the groups was 11.5 6 2 vs 11.7 6 2 months, respectively. Patient characteristics and comorbidities are given in Table I. In the later experience, stent grafts had a higher number of fenestrations/scallops incorporated in the graft design (2.7 6 0.8 vs 3.2 6 0.7; P < .001), with 40% of patients receiving grafts with three or more fenestrations compared with 8% in the early phase (Table II). Despite the increasing number of TVs over time, technical success improved from 92% to 98% between the two periods, in which a single TV catheterization failure occurred in only four patients in the later phase of the study. In the early period, three renals and three SMAs occluded during follow-up. In one case, the renal artery was sacrificed intraoperatively to seal a type I endoleak. In all other cases, the
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Table II. Stent graft configuration in the study period Configuration 1 fenestration (renal) 2 fenestrations (renal þ 2 fenestrations (renal þ SMA scallop 3 fenestrations (renal þ SMA) 3 fenestrations (renal þ SMA) þ CA scallop 4 fenestrations (renal þ SMA þ CA)
Early, %
Late, %
renal) renal) þ
2 (n ¼ 2) 22 (n ¼ 22) 66 (n ¼ 66)
0 (n ¼ 0) 3 (n ¼ 6) 55 (n ¼ 103)
renal þ
2 (n ¼ 2)
2 (n ¼ 4)
renal þ
4 (n ¼ 4)
28 (n ¼ 53)
renal þ
4 (n ¼ 4)
12 (n ¼ 22)
CA, Celiac trunk; SMA, superior mesenteric artery. There was a trend toward more fenestrations (with or without scallops) in the later phase of the study. Early and late denote early and late groups.
patients were asymptomatic and the occlusions were detected on routine follow-up. In the later phase, seven renals and one SMA occluded. In one case, the fenestrated component migrated distally, crushing stents in both renal arteries and in the SMA, which rendered the patient dialysis dependent. All other renal occlusions were asymptomatic. Whereas procedure time remained unchanged, contrast material volume and radiation time decreased significantly by 27% and 20%, respectively (Figs 1 and 2). More important, there was a 20% reduction in the iodine load for each patient (54 g vs 43 g; P ¼ .004), partly as a result of more frequent use of lower strength contrast media (100140 mg iodine/mL). Despite the possible long-term benefit on renal function, there were no statistically significant differences in plasma creatinine levels between the early and late groups in preoperative measurements (109 6 38 vs 109 6 81 mmol/L) or at hospital discharge (151 6 86 vs 129 6 77 mmol/L). Operative mortality occurred in two patients (2%) in the early phase and in four patients (2.1%) in the later phase. All deaths except one were associated with technical causes: iliac artery rupture in poor iliac access (n ¼ 1), aneurysm rupture during the procedure (n ¼ 1), renal artery perforation with massive retroperitoneal bleeding (n ¼ 1), mesenteric embolization with multiorgan failure (n ¼ 2), and postoperative myocardial infarction (n ¼ 1). A summary of operative outcomes is given in Table III. At 1 year, abdominal aortic aneurysm diameter decreased $5 mm in 54% of patients in the early group and in 62% of patients in the late group (P ¼ .3) (Fig 3). Similar results for aneurysm expansion were 5% and 2%, respectively. Of the five expanding aneurysms, two were found to have type I endoleak (both in the early group) and one a type II endoleak (late group) at 1-year followup. No differences were found in reintervention rates or endoleaks at 1-year follow-up (Table IV). DISCUSSION Randomized trials have shown a marked benefit of EVAR compared with open repair with respect to early operative morbidity and mortality.12-14 Despite this, EVAR carries device-specific limitations that can predispose
Fig 1. A scattergram showing the volume of contrast material used during procedures, illustrating the reduction of volumes with growing experience. Dates are in the form of yy-mm-dd.
Fig 2. A scattergram showing the reduction in intraoperative radiation time with more experience. Dates are in the form of yy-mm-dd.
patients to further hospital admissions and secondary interventions. Among these is the risk of incomplete sealing in the aneurysm neck, allowing continuous repressurization of the aneurysm sac with risk of late rupture. Recent reports on anatomic suitability for EVAR indicate that only half of patients fulfill the stent graft manufacturer’s instructions for use for safe and durable treatment.11 EVAR performed in a setting outside the instructions for use has been shown to increase the risk for intraoperative failure, postoperative complications, and late aneurysm expansion.15,16 During FEVAR, the stent graft is moved more proximally to the level of the visceral arteries. By doing so, blood flow to vital organs is secured through fenestrations in the graft fabric while achieving a more proximal seal (Fig 4). In contrast to standard EVAR systems, a FEVAR device is custom-made for each individual patient based on accurate
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Table III. Operative results
Procedure time, minutes Fluoroscopy time, minutes Contrast volume, mL Iodine load, g TVs Stented TVs 30-day mortality
Table IV. Results at 1-year follow-up Early
Late
P
276 6 91 84 6 41 254 6 120 54 6 25 2.7 6 0.8 64% 2.0%
280 6 133 68 6 63 184 6 90 43 6 18 3.2 6 0.7 77% 2.1%
NS .05 <.05 .004 <.01 <.01 NS
NS, Not significant; TVs, target vessels. Early and late denote early and late groups.
Fig 3. A scattergram of change in aneurysm size at 1-year follow-up. Measurements are in millimeters. AAA, Abdominal aortic aneurysm.
measurements on preoperative CT angiography reconstructions and is therefore not available in acute situations. Manufacturing time is 4 to 6 weeks. In addition, the procedure is technically challenging, and a multitude of sheaths, catheters, and wires are used for TV catheterization. This results in longer operation time, more radiation and contrast material exposure, and a procedure-specific spectrum of complications.17-20 The Zenith fenestrated abdominal aortic aneurysm endovascular graft has been commercially available in the European Union since late 2005 and was approved by the Food and Drug Administration in the United States in April 2012.21 During the development phase, our centers had the opportunity to use the device on selected patients along with a few other centers. The first procedure was performed in Malmö in 2002 and in Lille in 2004. Since then, the volume of treatments has gradually increased, and FEVAR is now considered the treatment of choice for juxtarenal aneurysms in both centers, with promising early and intermediate results.17 In our early experience, a limiting factor was the technical challenge of TV catheterization, resulting in extended operation time, high radiation dose, and large amounts of
Type I endoleak Type II endoleak Reinterventions Decreasing AAA diameter Expanding AAA diameter AAA mortality Overall mortality
Early, %
Late, %
P
1.2 14 8 54 5 3.0 4
1.0 10 12 61 2 3.2 7
NS NS NS NS NS NS NS
AAA, Abdominal aortic aneurysm; NS, not significant. Early and late denote early and late groups.
contrast media used in comparison to standard infrarenal EVAR.18-20,22 From a planning perspective, including fenestrations for the renal arteries only and placing a scallop for the SMA seem to be relatively reproducible.23 Because only the renal fenestrations are stented, only these need to be placed accurately to their TV. In the early experience, the SMA scallop was used merely as a “safety” and its position largely ignored during implantation. It was assumed that if the plan was correct, the position of the SMA scallop would be correct. Experience showed, however, that unstented SMA scallops were at an increased risk of postoperative occlusion because of a partial shuttering effect.17,24,25 Accurate determination of the rotational position of an SMA scallop by intraoperative angiography is quite difficult. This insight gradually led to the practice of routinely stenting SMA scallops and later replacing the scallop with a stented, large “strut-free” fenestration. As we became more comfortable with both planning and delivery, the addition of an extra SMA fenestration became more routine. The initial fear that this dramatically increased the risk of the procedure was not reflected in clinical outcomes. It does, however, add an extra TV to catheterize and stent. Our results show that the technical success rate remains high despite the increased number of fenestrations on the graft and the increased number of stented TVs. The total operative time remains unchanged despite the increased complexity of the fenestrated cuff. This might reflect an increased skill in catheterization and stenting of the TV but also that this part of the total procedure is relatively small. The additional time to catheterize and stent an extra TV is offset by the large number of other steps involved in a FEVAR procedure. The catheterization and stenting of the TV is, however, the part that is most dependent on fluoroscopy for guidance, and this was also reduced in the second part of the study. The total amount of contrast material used was reduced over time. Initially, repeated runs of 10 to 20 mL of contrast material were often used in positioning the fenestrated component in relation to the TV. This probably reflected both a lack of confidence in the device planning and a lesser ability to estimate the way the fenestrated device conformed in vivo as opposed to the preoperative imaging. In the later phase, particularly when facing tortuosity in the sealing region, we adopted the practice of precatheterizing one or several
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Fig 4. A, Preoperative computed tomography (CT) scan in anterior-posterior projection showing juxtarenal aneurysm but normal configuration suprarenal aorta. B, In lateral projection, a bulge is seen posterior to the origin of the superior mesenteric artery (SMA), indicating suprarenal extension of disease. C, Completion angiography after implantation of a four-fenestrated stent graft. D, CT angiography at 1 month postoperatively with excluded aneurysm and all visceral arteries stented and patent.
of the TVs to guide device positioning. This reduces the need for repeated runs of contrast material during device deployment as the position can be estimated with help of the catheters placed in the TV. In addition to reducing the contrast material volume, we now routinely use lower strength contrast media (100-140 mgI/mL) to reduce the contrast material load. In the years after this study, we have taken this a step further by using intraoperative imaging fusion techniques. This allows us to mark the TV on the basis of the preoperative CT angiography imaging, thus reducing the need for contrast material intraoperatively even further.19 In parallel to this more selective use of radiation and contrast material, other technical developments have been made that might influence and perhaps reduce the time
of implantation. Knowledge of which catheters and sheaths that perform in a specific manner has made the procedures easier. The technique of catheterizing and stenting a visceral vessel in the context of FEVAR is vastly different from that in treating occlusive disease, for example, and these skills are improved with experience. Despite the increase in numbers of stented TVs, the difference in endoleaks, sac shrinkage, and survival is not significant at 1-year follow-up. Previously published longterm outcomes from the initial cases indicate that durability up to 5 years is excellent in this cohort. The trend of incorporating a higher number of TVs can thus be questioned. It is possible that radiation time and contrast material volumes could be reduced further by avoiding the tendency to incorporate more TVs. Only long-term durability data will
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reveal if the addition of more fenestrations and a more proximal graft placement will also lead to fewer longterm failures. Long-term follow-up is limited to a few early adopting centers and seems to suggest that type I endoleaks are more common in patients with renal fenestrations only (personal communication, Tara Mastracci, Cleveland Clinic Foundation, Ohio). There are a number of limitations to this study. The retrospective nature implies that the patients are not exactly matched with regard to aneurysm anatomy, and this might affect the analysis. The exclusion of patients with thoracoabdominal aortic aneurysm partially compensates for this, but the number of patients with necks too short for standard EVAR vs those with true juxtarenal aneurysm is unknown and would require a complete re-review of the preoperative imaging, and this was outside the scope of the current study. Furthermore, changes in planning and operative management often come as small incremental improvements. This is similar to the overall development of endovascular procedures. For composite, complex endovascular procedures such as implantation of fenestrated stent grafts, the multitude of steps involved in the procedure in addition to the multitude of endovascular tools used make it virtually impossible to pinpoint when in time a significant change occurs. It is therefore difficult to exactly define a learning curve cutoff, and this makes the interpretation more difficult. CONCLUSIONS With increasing experience and patient selection, FEVAR planning and design have changed, with more visceral vessels targeted for better proximal seal while operative risk remains low. Simultaneously, radiation time, contrast material volume, and iodine load have been reduced, with possible long-term benefits for the patient. Long-term follow-up is needed to evaluate the effect of these changes on FEVAR durability. AUTHOR CONTRIBUTIONS Conception and design: TR, SH Analysis and interpretation: MS, JS, TR, BS, ND, SH, TK Data collection: MS, JS, TK Writing the article: MS, TR, TK Critical revision of the article: MS, JS, TR, BS, ND, SH, TK Final approval of the article: MS, JS, TR, BS, ND, SH, TK Statistical analysis: TK Obtained funding: Not applicable Overall responsibility: TK REFERENCES 1. Tambyraja AL, Fishwick NG, Bown MJ, Nasim A, McCarthy MJ, Sayers RD. Fenestrated aortic endografts for juxtarenal aortic aneurysm: medium term outcomes. Eur J Vasc Endovasc Surg 2011;42:54-8. 2. Hinchliffe RJ, Ivancev K, Sonesson B, Malina M. “Paving and cracking”: an endovascular technique to facilitate the introduction of aortic stent-grafts through stenosed iliac arteries. J Endovasc Ther 2007;14:630-3.
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3. Peterson BG. Conduits and endoconduits, percutaneous access. J Vasc Surg 2010;52(Suppl):60S-4S. 4. Peterson BG, Matsumura JS. Internal endoconduit: an innovative technique to address unfavorable iliac artery anatomy encountered during thoracic endovascular aortic repair. J Vasc Surg 2008;47: 441-5. 5. Rahimi SA, O’Donnell PL, Graham AM. Endovascular repair of abdominal aortic aneurysm with extreme iliac artery tortuosity. Vasc Endovascular Surg 2010;44:472-4. 6. Carpenter JP, Baum RA, Barker CF, Golden MA, Mitchell ME, Velazquez OC, et al. Impact of exclusion criteria on patient selection for endovascular abdominal aortic aneurysm repair. J Vasc Surg 2001;34:1050-4. 7. Moritz JD, Rotermund S, Keating DP, Oestmann JW. Infrarenal abdominal aortic aneurysms: implications of CT evaluation of size and configuration for placement of endovascular aortic grafts. Radiology 1996;198:463-6. 8. 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;50:738-48. 9. Park JH, Chung JW, Choo IW, Kim SJ, Lee JY, Han MC. Fenestrated stent-grafts for preserving visceral arterial branches in the treatment of abdominal aortic aneurysms: preliminary experience. J Vasc Interv Radiol 1996;7:819-23. 10. Kristmundsson T, Sonesson B, Malina M, Bjorses K, Dias N, Resch T. Fenestrated endovascular repair for juxtarenal aortic pathology. J Vasc Surg 2009;49:568-74; discussion: 574-5. 11. Canning C, Martin Z, Colgan MP, Abdulrahim O, McCafferty M, Fitzpatrick J, et al. Fenestrated endovascular repair of complex aortic aneurysms. Ir J Med Sci 2014 Mar 6. [Epub ahead of print]. 12. Chahwan S, Comerota AJ, Pigott JP, Scheuermann BW, Burrow J, Wojnarowski D. Elective treatment of abdominal aortic aneurysm with endovascular or open repair: the first decade. J Vasc Surg 2007;45: 258-62; discussion: 262. 13. Prinssen M, Verhoeven EL, Buth J, Cuypers PW, van Sambeek MR, Balm R, et al. A randomized trial comparing conventional and endovascular repair of abdominal aortic aneurysms. N Engl J Med 2004;351:1607-18. 14. United Kingdom EVAR Trial Investigators, Greenhalgh RM, Brown LC, Powell JT, Thompson SG, Epstein D, Sculpher MJ. Endovascular versus open repair of abdominal aortic aneurysm. N Engl J Med 2010;362:1863-71. 15. Schanzer A, Greenberg RK, Hevelone N, Robinson WP, Eslami MH, Goldberg RJ, et al. Predictors of abdominal aortic aneurysm sac enlargement after endovascular repair. Circulation 2011;123:2848-55. 16. 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;8:457-64. 17. Kristmundsson T, Sonesson B, Dias N, Tornqvist P, Malina M, Resch T. Outcomes of fenestrated endovascular repair of juxtarenal aortic aneurysm. J Vasc Surg 2014;59:115-20. 18. Mohapatra A, Greenberg RK, Mastracci TM, Eagleton MJ, Thornsberry B. Radiation exposure to operating room personnel and patients during endovascular procedures. J Vasc Surg 2013;58:702-9. 19. Maurel B, Hertault A, Sobocinski J, Le Roux M, Martin Gonzalez T, Azzaoui R, et al. Techniques to reduce radiation and contrast volume during EVAR. J Cardiovasc Surg 2014;55(Suppl 1):123-31. 20. Maurel B, Sobocinski J, Perini P, Guillou M, Midulla M, Azzaoui R, et al. Evaluation of radiation during EVAR performed on a mobile Carm. Eur J Vasc Endovasc Surg 2012;43:16-21. 21. Unno N, Yamamoto N, Higashiura W, Suzuki M, Mano Y, Sano M, et al. Early experience with fenestrated stent grafts for treatment of juxtarenal aortic aneurysm. Ann Vasc Dis 2013;6:642-50. 22. Panuccio G, Greenberg RK, Wunderle K, Mastracci TM, Eagleton MG, Davros W. Comparison of indirect radiation dose estimates with directly measured radiation dose for patients and operators during complex endovascular procedures. J Vasc Surg 2011;53: 885-94.e1; discussion: 894.
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23. Malkawi AH, Resch TA, Bown MJ, Manning BJ, Poloniecki JD, Nordon IM, et al. Sizing fenestrated aortic stent-grafts. Eur J Vasc Endovasc Surg 2011;41:311-6. 24. England A, Garcia-Finana M, Fisher RK, Naik JB, Vallabhaneni SR, Brennan JA, et al. Migration of fenestrated aortic stent grafts. J Vasc Surg 2013;57:1543-52.
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25. Verhoeven EL, Vourliotakis G, Bos WT, Tielliu IF, Zeebregts CJ, Prins TR, et al. Fenestrated stent grafting for short-necked and juxtarenal abdominal aortic aneurysm: an 8-year single-centre experience. Eur J Vasc Endovasc Surg 2010;39:529-36. Submitted Aug 12, 2014; accepted Nov 4, 2014.