Influence of endograft oversizing on device migration, endoleak, aneurysm shrinkage, and aortic neck dilation: results from the zenith multicenter trial☆

Article Outline

• Abstract
• Methods
• Results
  • Migration
  • AAA shrinkage
  • Aortic neck dilation
  • Endoleak
  • Other end points
• Discussion
  • Oversizing and migration
  • Oversizing and aortic neck change
  • Oversizing and endoleak and shrinkage rates
  • Limitations
• Conclusions
• APPENDIX. 
  • National primary investigators
  • Principal site investigators (and site enrollments)
• References
• Copyright

Abstract 

Background

Generous endograft oversizing has been associated with propensity for aortic neck dilation and subsequent device migration in endografts without suprarenal fixation. Effects of variable oversizing of endografts with suprarenal fixation have been poorly studied.

Methods

Three hundred fifty-one patients underwent endovascular AAA repair (EVAR) in a prospective multicenter trial using the Zenith AAA Endovascular Graft, a fully supported bifurcated 3-piece endograft with barb-enhanced suprarenal stent fixation. Blinded core-laboratory measurement of variables was prospectively recorded at predischarge and at 1, 6, 12, and 24 months after the procedure. Potential influence of endograft oversizing on subsequent aortic neck dilation (minor axis), aneurysm shrinkage (major axis), device migration, endoleak, rupture, open conversion, and death were retrospectively studied. Data are given as mean ± SEM.

Results

Risk of endograft migration (>5mm) at 12 months was 2.3% (6/261). However, patients with endograft oversizing of >30% had a 14% (4/29) migration risk compared with those oversized ≤30% (0.9%, 2/232), P < .002. There was zero device migration by the SVS definition (>10 mm or clinical event). Device oversizing >30% was associated with decreased AAA sac shrinkage (48% vs 77%) and with increased sac enlargement (9.5% vs 0.6%) at 24 months when compared with oversizing of ≤30%, respectively (P = .001). Incidence rate of any endoleak at 12 and 24 months was 8.2% (21/256) and 7.1% (12/169), respectively. Oversizing of endografts by >30% was associated with an increased type II endoleak rate (11 vs 4.7%) that failed to reach statistical significance (P = .27). Aortic neck diameters increased significantly by 6 months (P < .001) but then stabilized through 24 months; the absolute changes at 1 (n = 298), 6 (n = 278), 12 (n = 264), and 24 months (n = 171) were 0.66 ± 0.10 mm (3.0%), 1.32 ± 0.11 mm (5.6%), 1.38 ± 0.12 mm (5.9%), and 1.44 ± 0.16 mm (6.1%), respectively. Linear regression analysis demonstrated no correlation between endograft oversizing and aortic neck dilation at 12 (P = .86) or 24 months (P = .64).

Conclusions

Device migration and endoleaks were very infrequent after treatment with the Zenith AAA Endovascular Graft. However, endograft oversizing of >30% was associated with an ∼14-fold increase in device migration (>5 mm) at 12 months and with a ∼16-fold increased risk of AAA expansion at 24 months. Although further follow-up will be essential to assess whether these early associations continue, avoidance of excessive endograft oversizing is recommended.

Precise sizing of aortic endografts increasingly has been recognized as an important element in attaining optimal early and late outcomes after endovascular abdominal aortic aneurysm repair (EVAR). In particular, the increased risk of type I endoleaks with inadequate oversizing has been emphasized. Mohan et al1 found that the risk of type I endoleaks was significantly increased with oversizing of <10%. Using a model derived from these clinical data, they predicted a reduced type I endoleak rate with 10% to 20% device oversizing.1

Most endograft manufacturers indeed recommend a device oversize of 10% to 20% greater than the minor axis of the aortic neck. This degree of oversizing generally translates into use of an endograft that is 3 to 5 mm larger than the adventitia-to-adventitia measurement of the minor-axis aortic neck diameter. However, greater amounts of oversizing have been selectively used for a variety of reasons, including the perception that larger oversizing might be beneficial for treatment of challenging aortic neck anatomy.2 However, Conners et al3 found an association of >20% device oversizing with late aortic neck dilation and subsequent endograft migration. In that study, a self-expanding, modular, fully nitinol-supported device without hook or barb fixation had been employed.3 It is unknown whether other endograft designs will react similarly to generous oversizing.

The purpose of this study was to examine the potential influence of device oversizing on subsequent endograft migration, aneurysm sac changes, endoleak, and aortic neck dilation using a fully supported trimodular device with suprarenal barb-enhanced fixation.

Back to Article Outline

Methods 

This study was a retrospective analysis of multicenter data that was prospectively collected by a core-laboratory facility. Patients for EVAR were enrolled in the Zenith multicenter clinical trial. (For a list of the Zenith investigators, see the Appendix.) There were 3 EVAR cohorts: standard–medical risk group, high–medical risk group, and a “roll-in” group, consisting of patients with either standard or high medical risk. All groups had to conform to similar anatomic inclusion criteria and were thus pooled for purposes of this study. Detailed inclusion and exclusion criteria have been detailed elsewhere.4 Briefly, anatomic inclusion in the trial required an aortic neck of ≥15 mm in length and ≤28 mm in diameter, with ≤10% change in diameter in the first 15 mm of the neck. Angulation of the aortic neck to the aneurysm sac or the suprarenal aorta was limited to <60° and <45°, respectively.

The Zenith AAA Endovascular Graft is a bifurcated 3-piece device. It has a bare suprarenal stent with 10 to 12 barbs for enhanced fixation. It is fully supported with self-expanding Z-stents, placed on the inside of the Dacron material at the aortic and iliac fixation sites, and on the exterior of the device in the remainder of the body and limbs. The 5 available body lengths are designed to place the bifurcation of the device close to the iliac artery bifurcation. Aortic component devices are available in sizes from 22 to 32 mm, delivered through preloaded 18- to 20-Fr. sheaths. Iliac diameters extend to 24 mm, allowing treatment of ectatic common iliac vessels.

Anatomic patient selection was rigorously controlled by physician film reviewers who had no clinical interaction with the patient. Candidates were rejected from inclusion in the study if they did not fall within the previously described anatomic criteria. The suggested device oversizing at the aortic neck was 10% to 15%. The graft size that was implanted was based upon the collaboration between the national study proctors and investigator at each site. However, the site investigator made the final determination of all device sizing, including aortic oversizing.

Patients underwent computed tomography (CT) scanning postoperatively (within 7 days), then at 1, 6, and 12 months, and yearly thereafter. The study protocol mandated a CT slice thickness of ≤3 mm. CTs with and without intravenous contrast were required. Anatomic measurements used in this study were made by the study core laboratory personnel. Potential variation in measurement between investigative sites and the core laboratory was not examined.

Axial CT images were assessed on computer workstations (NIH Image), and measurements were performed electronically. A physician reviewer evaluated all chosen table positions against the entire CT as well as the outline of the vessel. Thus, all measurements were reviewed by a minimum of two people. Formal measurement of interobserver and intraobserver variability was not performed. Other imaging modalities (arteriograms, CT arteriograms, magnetic resonance arteriograms, and 3-D CT reconstructions) were not routinely required. Aortic neck diameter was measured in its minor axis from adventitia to adventitia. This measurement was taken at the ostium of the lowest renal artery. AAA sac size was measured at its major axis. The initial postoperative CT measurement of AAA size was employed as the baseline for subsequent comparison for changes is AAA sac size. Potential migration of the endograft was assessed by measuring the distance between the top of the bare suprarenal stent and the lowest renal artery. In cases in which the ostium of the lowest renal artery was seen in more than 1 cut, the image representing the more caudal aspect of the vessel was employed. The junction of the uncovered suprarenal stent and the covered portion of the endograft could not be reliably seen on axial CTs. Therefore, direct measurement of the distance between the lowest renal artery and the covered portion of the device was not possible.

Continuous and dichotomous measures were assessed using independent 2-sample t tests and Yates-corrected Pearson χ² tests, respectively. Change with time was assessed with multivariate repeated-measures ANOVA. Multivariate logistic regression was performed to assess predicate factors of outcome. All analyses were performed using Systat version 10.2 (SPSS, Chicago, IL). A P value of <.05 was considered significant.

The study design of this trial was a collaborative effort of the national primary investigators (R.K.G. and T.A.M.C.) and Cook, Inc, the study sponsor. Cook was also involved with data collection. The primary author (W.C.S.) and coauthors had unfettered access to all raw and tabulated data, including the source-imaging studies. Thus, the authors of this paper are solely responsible for the data analysis and interpretation, manuscript preparation, and timing of the manuscript's oral presentation and ultimate publication.

Back to Article Outline

Results 

Three hundred fifty-one patients were treated with the Zenith AAA Endovascular Graft in a multicenter FDA phase II trial. These patients included all standard-risk, high medical–risk, and “roll-in” cohorts. Of these, the large majority (88%, 309) had endograft oversizing of ≤30%, whereas 12% (41) had endografts that were oversized by >30%. There were 1 or more patients in whom the endograft was oversized by >30% at 13 of 15 investigative sites (range, 0 to 7 patients). One patient received a custom device and was excluded from these analyses.

Migration 

By recently revised Society for Vascular Surgery reporting standards, migration is considered to be >10-mm movement of the device or any endograft displacement with associated need for a secondary procedure.5 By this definition, endograft migration was zero (0/261) at 12 months. However, more modest caudal migration (>5 mm) was noted in 2.3 % (6/261) of patients at 12 months. No cranial migration was observed. Endograft oversizing of >30% was associated with a ∼14-fold increase in the risk of device migration (>5 mm) at this time point: 14% (4/29) incidence vs 0.9% (2/232) with ≤30% oversizing (P = .002). No patient with migration had clinical sequelae or need for a secondary procedure. A single barb fracture was seen in 1 patient with migration. Possible associated anatomic risk factors for migration were also examined (Table I). At 12 months, endograft oversizing was the only predictor of device migration (> 5 mm) with univariate and multivariate analysis. There were no significant differences in aortic neck length, diameter, angulation, or shape in patients with or without migration.

Table I. Possible anatomic risk factors for endograft migration (>5 mm) at 12 months

NA, Not applicable.

Additionally, the association of a flared aortic neck with device oversizing was examined. Patients with flared aortic necks were defined as those with ≥3 mm aortic neck enlargement that measured 15 mm caudal to the lowest renal artery ostium. There was a 15% (45/305) and 27% (11/41) rate of flared aortic necks in patients with ≤30% and >30% device oversizing, respectively (P = .08). There was no significant relationship between a flared neck and neck dilation at 12 months (P = .09) or at 24 months (P = .40) by linear regression analysis.

AAA shrinkage 

At 12 months, the entire cohort (Fig 1), 65% (174/268) experienced significant shrinkage (>5 mm sac reduction), 34 % (91/268) remained unchanged (−5 to + 5 mm), and 1.1 % (3/268) enlarged (>5 mm).4 At 24 months (Fig 2), there was a 73% (128/175), 25% (44/175), and 1.7% (3/175) rate of shrinkage, stability, and growth, respectively. Endograft oversizing by >30% was associated with a lower shrink rate (48% vs 77%) and with a ∼16-fold higher expansion rate (9.5% vs 0.6%) at 24 months that was significant (P = .001; Fig 2).

• 
  • View Large Image
  • Download to PowerPoint

• Fig 1. 

  Effect of device oversizing (≤30% vs >30%) on AAA sac behavior at 12 months. AAA shrinkage (Shrink) was considered >5 mm reduction, Unchanged was −5 to +5 mm change, and Growth was >5 mm increase in size.

• 
  • View Large Image
  • Download to PowerPoint

• Fig 2. 

  Effect of device oversizing (≤30% vs >30%) on AAA sac behavior at 24 months. AAA shrinkage (Shrink) was considered >5 mm reduction, Unchanged was −5 to +5 mm change, and Growth was >5 mm increase in size.

Aortic neck dilation 

When compared with the preoperative measurements, there was no significant increase in neck diameter at the immediate postimplant measurement (0.07 ± 0.12 mm, P = .57). When compared with the immediate postimplant diameter, there was significant aortic neck dilation by 6 months (1.3 mm, P < .001) that then plateaued through 24 months (Table 2 ). Percentage of device oversizing did not correlate with aortic neck dilation at 12 months (r² = 0; P = .86) or 24 months (r²=0.001; P = .69) by linear regression.

Table II. Changes in aortic neck diameter

Endoleak 

Risk of any endoleak was 8.2 % (21/256) at 12 months and 7.1 % (12/169) at 24 months. Most of these endoleaks were type II. Risk of a type I or III endoleak was 1.9% (5/256) at 12 months and 0 (0/169) at 24 months.4 Potential effect of device oversizing is shown in Table III . There was a >50% higher incidence rate of type II endoleaks with >30% device oversizing (4.8% vs 11%) that did not achieve statistical significance at 12 (P = .17) or 24 months (P = .27).

Table III. Possible effect of endograft oversizing on endoleak

NA, Not applicable.

Nine patients were identified intraoperatively with a proximal Type I endoleak, as noted by the site. Per protocol, aggressive treatment of Type I (proximal or distal) and Type III endoleaks was required. Treatment for the proximal Type I endoleaks identified during the procedure was physician dependent and ranged from use of a molding balloon (5 patients), molding balloon and Zenith main body extension (1 patient), and Zenith main body extension and commercially available stent (1 patient). Additionally, 1 patient was not treated at the time of the procedure, and this patient's Type I endoleak resolved by the time of hospital discharge. One additional patient had an endoleak that remained at the time of hospital discharge.

Other end points 

There was 1 late rupture in the entire cohort, occurring in the group whose endografts were oversized by ≤30% (0.3% [1/309] vs 0 [0/41], P = .99). Late open conversions were also infrequent and not statistically different between groups (1.3% [4/309] vs 2.4% [1/41], P = .99). There were no conversions to open repair in the first 30 days after EVAR. Finally, death at 12 months (6.1% [19/309] vs 7.3% [3/41], P = .99) and 24 months (12% [38/309] vs 20% [8/41], P = .30) was not different between those oversized ≤30% or >30%, respectively.

Back to Article Outline

Discussion 

Potential influence of endograft oversizing on subsequent adverse events after EVAR was evaluated from prospectively collected multicenter data.

Oversizing and migration 

Using this robust and impartial database, device migration at 12 months was found to be infrequent after treatment with the Zenith AAA Endovascular Graft. By the SVS definition of migration, there was zero incidence of endograft migration at 12 months. By a stricter definition of migration (>5 mm), 2.3% were noted to have caudal movement of the device at 12 months. Of these, ≤30% device oversizing was associated with a 0.9% (2/232) rate of migration, whereas there was a 14.1% (4/27) rate of migration in patients with >30% oversizing. These differences were highly significant (P = .001). Univariate and multivariate analysis of anatomic aortic neck characteristics failed to demonstrate any other significant variables that were associated with device migration.

Migration of the Zenith endograft has been an uncommon event in previous reports. In a single-center series from the University of California at San Francisco, no episodes of migration were seen after treatment of 116 patients with the Zenith endograft with a mean follow-up of 10.3 ± 9.8 months (range, 1 to 34 months).6 The Nottingham group reported a 5-year experience (mean follow-up of 20.6 ± 14.9 months) with the Zenith endograft, with only a single episode of migration (1/94, 1.1%).7 This case was associated with late aortic neck dilation. The 5-year cumulative migration rate in this study was 7% by Kaplan-Meier analysis.7 Finally, Greenberg et al8 reported on 528 patients treated in Europe, Australia, and the United States with a mean follow-up of 14 months (range, 1 to 36 months). In this large data set, 8 patients who had been treated with an earlier prototype of the device with fewer suprarenal barbs had migration at 2 to 3 years after implantation.8

Experimental studies have suggested that the suprarenal barb fixation of the Zenith endograft resists migration more rigorously than does many other endograft designs.9 The mean displacement force in a cadaveric model for the Zenith device was 24 N. An endograft with infrarenal hooks required 12.5 N, whereas a third endograft relying on radial force required only 4.5 N of displacement force.9 Aortic necks with larger diameters and significant angulation create greater static downward forces on the endograft, exceeding 8 to 12 N in some anatomic cases.10 This dynamic flow modeling has been confirmed in the clinical observation of high migration rates in patients with large aortic necks after treatment with an endograft without active fixation.11

The etiology of increased migration (>5 mm) with >30% device oversizing is unclear. The multiple suprarenal barbs of the device are frequently transmural in the aorta, with forceful caudal movement causing aortic tears in experimental models.9 This scenario is unlikely, as no suprarenal pseudoaneurysms have been seen in these patients. Migration of the device could infer failure of the barbs. However, isolated single-barb fractures have been seen in only a few patients. Moreover, the number of barbs (10-12) on the Zenith device was designed to provide redundant protection from migration. A second possible failure mode of the barbs would be initial failure of the barbs to penetrate the aorta. Routine use of a compliant “molding” balloon during implantation encourages engagement of the barbs. The downward orientation of the barbs may require 2 to 3 mm of device migration for full engagement of the aorta. Experimental models with Gianturco Z stent-based endografts have demonstrated folds in the proximal fabric with stent oversizing.12 These folds or invaginations in the fabric grew larger with increases in stent oversizing. Although type I endoleaks would seem to be the greatest concern regarding such a phenomenon, theoretically fixation of the device could also be compromised.

Oversizing and aortic neck change 

Changes in aortic neck diameter after EVAR could have important implications in long-term durability of this treatment. Significant dilation may lead to loss of seal or to fixation of the endograft, causing a proximal type I endoleak, caudal endograft migration, or both. The mechanisms of attaining a proximal seal and secure fixation differ significantly among endograft designs. The propensity for these severe adverse events after late aortic neck dilation could be device dependent, although this is speculative. Finally, the amount of late aortic neck dilation itself may be endograft dependent.

The present study found a small but significant change in aortic neck diameter at 6 months after implantation that then stabilized at 12 and 24 months. What factors might predispose to late aortic neck dilation? Conners et al3 found a strong correlation with >20% device oversizing and subsequent late neck dilation at 2 and 3 years after treatment with a self-expanding, modular, fully nitinol-supported device. However, increased device oversizing did not appear to accelerate aortic neck dilation by the 2-year mark in the present study. The reasons for disparity of these observations are speculative. The most obvious explanation is that different endograft designs may have variable late effects on the aortic neck. However, other anatomic factors or differences in other patient characteristics cannot be excluded as contributing factors.

Oversizing and endoleak and shrinkage rates 

Device oversizing by >30% had a negative impact on AAA sac behavior. At 24 months, the risk of AAA growth was elevated by ∼16-fold (9.5% vs 0.6%), and the incidence of AAA shrinkage was decreased (48% vs 77%) in those with >30% and ≤30% oversizing, respectively. In previous studies with Zenith13 and other endograft devices,14 increased endoleak rates have been associated with a decrease in AAA shrinkage.

In the current study, endoleaks were infrequent after treatment with the Zenith device (8.2% and 7.1% at 12 and 24 months, respectively). This low endoleak rate compared favorably with that seen with other endografts. Endoleak rates at 12 and 24 months in AneuRx trial patients15 were 13.9% and 16.7%, and in Excluder trial patients,16 the rates were 17% and 20%, respectively. In the Zenith study, >30% device oversizing was associated with >50% increase in type II endoleaks that did not achieve statistical significance. There were no differences in the more troublesome type I endoleak, but it is possible that some of the increase in type II endoleaks may have actually been misclassified type I leaks. Thus, although it would appear intuitive that higher endoleak rates might negatively affect shrink rates, a robust statistical correlation is lacking. As such, the underlying explanations for the striking negative effect of > 30% device oversizing on AAA sac behavior remain speculative.

Could the choice of >30% device oversizing simply be a marker for adverse anatomic characteristics that are known to negatively affect outcome? This study demonstrated no statistically significant differences in this area but did find some trends that ultimately could be clinically important. Those patients who experienced migration (>5 mm) at 12 months had shorter aortic necks (24.6 vs 33.3 mm, P = .17). Although this was not statistically significant, it is well known that the risk of migration increases with progressively shorter necks. There were a modestly greater percentage of patients with flared aortic necks in patients who had >30% device oversizing (27% vs 15%, P = .08). Patients with a flared aortic neck likely have a greater likelihood of late aortic neck dilation and resultant deleterious effects such as type I endoleaks or migration. Although this trend was not significant, further follow-up of possible such adverse anatomic findings is warranted.

Limitations 

Conventional measurement of endograft migration could not be performed with this endograft. Direct measurement of the distance between the lowest renal artery and the endograft was not possible because CT could not reliably appreciate the end of the bare suprarenal stent and the beginning of the endograft. Thus, a surrogate measurement from the top of the suprarenal stent to the lowest renal artery was employed. This longer length may have increased the chance for relative inaccuracies in measurement of migration. However, the absence of any observed cranial migration would suggest that the measurement of caudal migration was not a random measurement error.

Back to Article Outline

Conclusions 

Device migration and endoleaks were very infrequent after treatment with the Zenith AAA Endovascular Graft. However, oversizing of >30% was associated with an increased rate of device migration at 12 months and with a negative effect on late AAA sac changes. Endoleak occurrence and late aortic neck dilation were not significantly changed by oversizing. The underlying etiology for increased caudal movement (of >5 mm) and AAA sac growth with generous oversizing is speculative. Although further follow-up will be essential to assess whether these early associations continue, avoidance of excessive endograft oversizing is recommended.

Back to Article Outline

APPENDIX. 

National primary investigators 

Roy K. Greenberg, MD, Cleveland Clinic Foundation, Cleveland, Ohio

Timothy A.M. Chuter, MD, University of California, San Francisco, Calif

Principal site investigators (and site enrollments) 

Daniel Clair, MD (co-PI), and Sunita Srivastava, MD (co-PI), Cleveland Clinic Foundation, Cleveland, Ohio (85)

Steven G. Lalka, MD, Indiana University Medical Center, Indianapolis, Ind (53)

W. Charles Sternbergh III, MD, Ochsner Clinic Foundation, New Orleans, La (50)

Albert G. Hakaim, MD, Mayo Clinic Foundation, Jacksonville (32)

Barry S. George, MD, Midwest Cardiology Research Foundation, Columbus, Ohio (32)

Ronald M. Fairman, MD, University of Pennsylvania Medical Center, Philadelphia, Penn (28)

Linda M. Reilly, MD, University of California, San Francisco, Calif (28)

Frank J. Criado, MD, The Union Memorial Hospital, Baltimore, Md (25)

Richard M. Green, MD, Strong Memorial Hospital, Rochester (21)

David J. Porter, MD, Methodist Hospital, Indianapolis, Ind (20)

Frank J. Veith, MD, Montefiore Medical Center, Bronx, NY (19)

Richard P. Cambria, MD, Massachuchetts General Hospital, Boston, Mass (13)

Fredrick S. Keller, MD, Dotter Institute of Interventional Therapy, Portland, Ore (10)

Frank J. Miller Jr, MD (co-PI), Mark Sarfati, MD (co-PI), The University of Utah/VA Hospital, Salt Lake City, Utah (10)

Luis Sanchez, MD, Washington University School of Medicine, St Louis, Mo (6)

Back to Article Outline

References 

1. Mohan IV, Laheij JP, Harris PL  on behalf of the EUROSTAR collaborators . Risk factors for endoleak and the evidence for stent-graft oversizing in patients undergoing endovascular aneurysm repair. Eur J Vasc Endovasc Surg. 2001;21:344–349
   • View In Article
   • Abstract
   • Full-Text PDF (92 KB)
   • CrossRef
2. Criado F, Abul-Khoudoud O, Lucas PR, Barnatan MF. Challenges in stent grafting (dealing with difficult neck and iliac artery anatomy). Perspect Vasc Surg Endovasc Ther. 2001;14:41–56
   • View In Article
   • CrossRef
3. Conners MS, Sternbergh WC, Carter G, Tonnessen BT, Yoselevitz M, Money SR. Endograft migration 1-4 years after endovascular AAA repair with the AneuRx device (a cautionary note). J Vasc Surg. 2002;36:476–484
   • View In Article
   • Abstract
   • Full-Text PDF (819 KB)
   • CrossRef
4. Greenberg RK, Chuter TAM, Sternbergh WC III, for the Zenith investigators. The Zenith endovascular graft: results of the United States multicenter trial. J Vasc Surg (in review)
   • View In Article
5. Chaikof EL, Blankensteijn JD, Harris PL, White GH, Zarins CK, Bernhard VM, et al.  Reporting standards for endovascular aortic aneurysm repair. J Vasc Surg. 2002;35:1048–1060
   • View In Article
   • Abstract
   • Full Text
   • Full-Text PDF (102 KB)
   • CrossRef
6. Abraham CZ, Chuter TAM, Reilly LM, Okuhn SP, Pethan LK, Kerlan RB, et al.  Abdominal aortic aneurysm repair with the Zenith stent graft (short to midterm results). J Vasc Surg. 2002;36:217–225
   • View In Article
   • Abstract
   • Full-Text PDF (1406 KB)
   • CrossRef
7. Alric P, Hinchiffe RJ, MacSweeney STR, Wenham PW, Whitaker SC, Hopkinson BR. The Zenith Aortic Stent-graft (a 5-year single-center experience). J Endovasc Ther. 2002;9:719–728
   • View In Article
   • MEDLINE
   • CrossRef
8. Greenberg RK, Lawrence-Brown M, Bhandari G, Hartley D, Stelter W, Umscheid T, et al.  An update of the Zenith endovascular graft for abdominal aortic aneurysms (initial implantation and mid-term follow-up data). J Vasc Surg. 2001;33:S157–164
   • View In Article
   • MEDLINE
9. Resch T, Malina M, Lindblad B, Malina J, Brunkwall J, Ivancev K. The impact of stent design on proximal stent-graft fixation in the abdominal aorta (an experimental study). Eur J Vasc Endovasc Surg. 2000;20:190–195
   • View In Article
   • Abstract
   • Full-Text PDF (208 KB)
   • CrossRef
10. Matsumura JS, Hoff FL, Pearce WH. Incidence and causes of proximal device migration after EVAR. Paper presented at: VEITH symposium; November 21, 2002; New York
    • View In Article
11. Lee JT, Lee J, Aziz I, Donayre CE, Walot I, Kopchok GE, et al.  Stent-graft migration following endovascular repair of aneurysms with large proximal necks (anatomical risk factors and long-term sequeli). J Endovasc Ther. 2002;9:652–664
    • View In Article
    • MEDLINE
    • CrossRef
12. Schurink GWH, Aarts NJM, van Baalen JM, Kool LJS, van Bockel JH. Stent attachment site-related endoleakage after stent graft treatment (an in vitro study of the effects of graft size, stent type, and atherosclerotic wall changes). J Vasc Surg. 1999;30:658–667
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (183 KB)
    • CrossRef
13. Sternbergh WC, Conners MS, Tonnenson B, Carter G, Money SR. Aortic aneurysm sac shrinkage after endovascular repair is device dependent (a comparison of Zenith and AneuRx endografts). Ann Vasc Surg. 2003;17:49–53
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (474 KB)
    • CrossRef
14. Zarins CK, White RA, Hodgson KJ, Schwarten D, Fogarty TJ. Endoleak as a predictor of outcome after endovascular aneurysm repair (AneuRx multicenter clinical trial). J Vasc Surg. 2000;32:90–107
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (217 KB)
    • CrossRef
15. for the AneuRx Clinical Investigators Zarins CK. The US AneuRx clinical trial (6-year clinical update 2002). J Vasc Surg. 2003;37:904–908
    • View In Article
    • Abstract
    • Full Text
    • Full-Text PDF (126 KB)
    • CrossRef
16. Matsumura JS, Brewster DC, Makaroun MS, Naftel DC. A multicenter controlled clinical trial of open versus endovascular treatment of abdominal aortic aneurysms. J Vasc Surg. 2003;37:262–271
    • View In Article
    • Abstract
    • Full-Text PDF (254 KB)
    • CrossRef