Mid- and long-term device migration after endovascular abdominal aortic aneurysm repair: a comparison of AneuRx and Zenith endografts

BACKGROUND: Freedom from migration is key to the durability of endovascular aneurysm repair (EVAR). This study evaluates the mid- and long-term incidence of migration with two different endografts. METHODS: Between September 1997 and June 2004, 235 patients were scheduled for EVAR with an AneuRx (Medtronic/AVE Inc.) or Zenith (Cook) endograft. Patients with fusiform, infrarenal aneurysms and a minimum 12 months of follow-up were analyzed, for a final cohort of 130 patients. Migration was assessed on axial computed tomography (CT) (2.5 to 3 mm cuts) as the distance from the most caudal renal artery to the first slice containing endograft (AneuRx) or to the top of the bare suprarenal stent (Zenith). Aortic neck diameters were measured at the most caudal renal artery. The initial postoperative CT scan was the baseline. Migration was defined by caudal movement of the endograft at two thresholds, > or =5 mm and > or =10 mm, or any migration with a related clinical event. RESULTS: Life-table analysis demonstrated AneuRx freedom from migration (> or =10 mm or clinical event) was 96.1%, 89.5%, 78.0%, and 72.0% at 1, 2, 3, and 4 years, respectively. Zenith freedom from migration was 100%, 97.6%, 97.6%, and 97.6% at 1, 2, 3, and 4 years, respectively (P = .01, log-rank test). The stricter 5-mm migration threshold found 67.4% of AneuRx and 90.1% of Zenith patients free from migration at 4 years of follow-up. Twelve out of 14 (85.7%) AneuRx patients (12/14) with migration (> or =10 mm or clinical event) underwent 14 related secondary procedures (13 endovascular, 1 open conversion). The single Zenith patient with migration (> or =10 mm) has not required adjuvant treatment. Mean follow-up was 39.0 +/- 2.3 months (AneuRx) and 30.8 +/- 1.9 months (Zenith, P = .01). Patients with and without migration did not differ in age, gender ratio, aneurysm diameter, and neck diameter. However, initial neck length was shorter in patients with migration (22.1 +/- 2.1 mm vs 31.2 +/- 1.2 mm, P = .02). A subset of patients (21.6%) experienced significant (defined as > or =3 mm) maximum aortic neck dilation. Of the AneuRx patients, > or =3 mm aortic neck dilation affected 30.8% of migrators vs 13.0% of nonmigrators (P = .20). CONCLUSIONS: Endograft migration is a time-dependent phenomenon affected by both device choice and aortic neck length. A great majority of patients (85.7%) with migration of the AneuRx device ultimately required treatment. A minority of patients experienced aortic neck dilation that could be considered clinically significant. Careful surveillance for migration is an essential component of long-term follow-up after EVAR.     

Most patients with abdominal aortic aneurysm are not suitable for endovascular repair using currently approved bifurcated stent-grafts

Strict morphologic criteria must be used for patient selection to achieve durable success with endovascular aortic aneurysm repair (EVAR). The goal of this study was to assess morphologic suitability (MS) of abdominal aortic aneurysms (AAAs) for 2 currently approved bifurcated stent grafts and identify reasons for exclusion from EVAR. The authors reviewed the electronic charts of 1,795 consecutive patients who were diagnosed as having AAA between January 1999 and July 2001 at their institution. Three hundred and twenty patients had an AAA with a diameter of > or = 5.0 cm, measured on computed tomography (CT). The records of 301 patients, 254 men, 47 women, with a mean age of 74 years were available for review, and these patients constituted the study cohort. Criteria used for MS included a proximal neck length > or = 15 mm; neck diameter between 18 and 26 mm; neck angulation < or = 60 degrees ; common or external iliac artery (CIA or EIA) diameters of 7-16 mm and 8-13 mm, respectively, for AneuRx (Medtronic Ave, Santa Rosa, CA) and Ancure (Guidant Cardiac and Vascular Division, Menlo Park, CA) bifurcated grafts. AAAs were suitable for AneuRx device in 14% of patients (43 of 301; 95% CI = 11-19%) and for Ancure in 5% (16 of 301; 95% CI = 3.1-9%). The main reason for exclusion was an inadequate proximal aortic neck (73%). The neck was too short in 49.5%, too wide in 64% and badly angulated in 12% of the patients. Iliac artery morphology precluded EVAR with AneuRx and Ancure devices in 52% and 80%. Both CIAs were too wide for EVAR in 43% and 77%, respectively. When iliac artery diameter < or = 20 mm was accepted, iliac suitability for AneuRx increased from 49% to 70% and overall suitability increased from 14% to 20%. When more permissive criteria were used for MS (neck length > or = 10 mm, neck diameter < or = 30 mm, CIA < or = 20), 39% of patients became candidates for EVAR. More than three fourths of the patients with an AAA > or = 5.0 cm in size, seen in a tertiary referral center, are morphologically not suitable for EVAR using 2 currently approved bifurcated endografts. The main reasons for exclusion are a short or wide proximal aortic neck. Considerable changes in size of the devices and in proximal attachment techniques have to occur before most AAAs will be suitable for EVAR.     

Outcomes of endovascular AAA repair in patients with hostile neck anatomy using adjunctive balloon-expandable stents

Hostile neck anatomy remains the predominant reason that patients are denied endovascular aneurysm repair (EVAR). We reviewed our experience of EVAR with use of prophylactic adjunctive proximal balloon-expandable stents in patients with hostile neck anatomy and adjunctive proximal balloon-expandable stents in patients with type I endoleaks. Of 140 patients who underwent EVAR between 2000 and 2004, we reviewed data for 19 patients in whom we used proximal balloon-expandable stents. By high-resolution computed tomography scan or angiography, hostile neck anatomy was classified as length <15 mm, neck diameters > or =26 mm, circumferential thrombus at the proximal neck, angulated neck > or =60 degrees, and neck bulge or reverse taper necks. Patients were considered to have hostile anatomy if they met 1 or more of the above-cited criteria. All patients underwent AAA repair with commercially available endograft systems, Zenith (Cook, Bloomington, IN) and AneuRx (Medtronic/AVE, Minneapolis, MN). Balloon-expandable stents utilized included Cordis-Palmaz stents (17/19) and eV3 Max stents (2/19). Stents were deployed in the proximal graft with transrenal extension. AneuRx (18/19) and Zenith (1/19) endografts were used in all of the patients. Of the 19 patients, 15 had prophylactic stent placement for known hostile neck anatomy and 4 patients had stent placement for type I endoleak. Assisted primary technical success was achieved in all patients. Three patients had maldeployment of the endograft or proximal stent requiring additional endovascular interventions at the time of surgery. No endografts were deployed too low requiring stent placement. Procedure-related complications occurred in 2 of 19 patients. These included 1 operative death secondary to pneumonia and 1 patient who developed progressive renal failure. Short-term clinical success was achieved in 17 of 19 patients. Two patients required secondary interventions, 1 due to device migration with secondary conversion to open repair, and an endoleak, which, on angiogram, was a large type II endoleak successfully treated with coiling of the inferior mesenteric artery. One patient was observed to have a type II endoleak with no associated aneurysm enlargement. Short-term results suggest the use of prophylactic adjunctive balloon-expandable stents may decrease the incidence of secondary interventions related to hostile neck anatomy when used as an adjunctive measure with EVAR. Based on our experience, we feel EVAR may be offered to an expanded patient population with hostile neck anatomy with use of prophylactic balloon-expandable stents.     

Aortic Neck Dilation after Endovascular Abdominal Aortic Aneurysm Repair: Should Oversizing Be Blamed?

Long-term durability after endovascular abdominal aortic aneurysm repair (EVAR) is dependent upon the maintenance of an effective seal between the endograft and the proximal landing zone. Continuous neck dilation might lead to the loss of such a seal. This study aims at evaluating the incidence, risk factors, and clinical consequences of post-EVAR aneurysm neck dilation in patients treated with two types of endografts: AneuRx^® and Ancure^®. We reviewed data concerning all consecutive patients submitted to primary EVAR using the AneuRx and Ancure devices. Preoperative neck anatomic characteristics (diameter, calcification, and thrombus load) were evaluated, and device oversize percentage was calculated. Postoperative same-level neck diameter was measured on all postoperative computed tomographic (CT) scans. Probabilities of neck dilation (≥10% and ≥15%) relative to preoperative diameter and first postoperative diameter were estimated with the Kaplan-Meier method and compared between patients using both types of endograft. The impact of anatomic characteristics on neck dilation incidence was evaluated using Cox proportional hazards models. Mean neck dilation was compared between patients with and without device migration and proximal type I endoleak. Both groups had similar probabilities of dilating >10% relative to preoperative diameter and to first postoperative diameter. Proximal necks in AneuRx-treated patients had higher probabilities of dilating ≥15% relative to preoperative diameter than Ancure-treated patients (45.5% vs. 18.7% at 1.5 years, p = 0.025), but the probability of such dilation relative to the first postoperative diameter was not different between the two groups (12.4% vs. 9.1% at 1.5 years, p = 0.832). None of the preoperative neck characteristics was associated with neck dilation risk. Device oversize percentage was correlated with the percentage of neck dilation at first postoperative CT scan relative to preoperative diameter in both the AneuRx (correlation coefficient = 0.469, p < 0.0001) and the Ancure (correlation coefficient = 0.464, p < 0.011) groups, but it was not correlated with the percentage of neck dilation at 1 or 1.5 years relative to first postoperative CT scan in either group. Patients with and without caudad device migration (≥5 mm) had similar percentages of neck dilation at 1.5 years relative to preoperative diameter, but migrators had higher mean percentages of dilation at 1.5 years relative to first postoperative neck diameter (11.4% vs. 5.6, p = 0.012). Two phenomena may be differentiated: an immediate postimplant dilation, strongly correlated with the percentage of oversize and more likely to reach values ≥15% with an AneuRx device than with an Ancure graft, and a subsequent dilation, relative to the first postoperatively measured diameter, equally probable with either type of device, not correlated with the percentage of oversizing but associated with caudad device migration. Our study does not support any adverse role for the degree of oversize.Presented at the Twenty-sixth Meeting of the Canadian Society for Vascular Surgery, October 22-23, 2004, Quebec City, Quebec, Canada.J. M. Panneton is currently at Eastern Virginia Medical School and Vascular and Transplant Specialists, Norfolk, VA.     

Endoluminal repair of infrarenal abdominal aortic aneurysms using a modular stent-graft: one-year clinical results from a European multicentre trial.

This is a report of a prospective study to evaluate the safety and efficacy of the Medtronic AneuRx stent-graft. Patients with an infrarenal aneurysm with a proximal neck length of greater than 10 mm and a neck diameter not greater than 26 mm and iliac artery diameters of at least 6 mm were accepted for endovascular repair using the Medtronic AneuRx modular stent-graft. A total of 104 patients were included in the study. Transfemoral placement of the bifurcated stent-graft was successful in 102 of 104 patients. Two conversions were performed. The mean operating time was 148 min (range 75-480) and the mean blood loss was 605 ml (range 100-2900). The mean follow-up was 15 months (range 12-21). Complications were rare and no kinking or migration occurred. At follow-up, four endoleaks persisted after 12 months. The Medtronic AneuRx stent-graft is a safe and efficacious alternative to open abdominal aortic aneurysm repair with excellent early results.     

Stent graft migration after endovascular aneurysm repair: importance of proximal fixation

OBJECTIVE: We reviewed the incidence of stent-graft migration after endovascular aneurysm repair in a prospective multicenter trial and identified factors that may predispose to such migration. METHODS: All patients who received treatment during the course of the multicenter AneuRx clinical trial were reviewed for evidence of stent-graft migration over 5 years, from 1996 to 2001. Post-deployment distance from the renal arteries to the proximal end of the stent graft and the proximal fixation length (length of the infrarenal neck covered by the stent graft) were determined in patients for whom pre-procedure and post-procedure computed tomography scans were measured in an independent core laboratory. RESULTS: Stent-graft migration was reported in 94 of 1119 patients, with mean time after device implantation of 30 +/- 11 months. Freedom from migration was 98.6% at 1 year, 93.4% at 2 years, and 81.2% at 3 years (Kaplan-Meier method). Subset (n = 387) analysis revealed that initial device deployment was lower in 47 patients with migration, as evidenced by a greater renal artery to stent-graft distance (1.1 +/- 0.7 cm), compared with 340 patients without migration (0.8 +/- 0.6 cm; P =.006) on post-implantation computed tomography scan. Proximal fixation length was shorter in patients with migration (1.6 +/- 1.4 cm) compared with patients without migration (2.3 +/- 1.4 cm; P =.005). There was significant variation in migration rate among clinical sites (P <.001), ranging from 0% to 30% (median, 8%), with a greater than twofold difference in migration rate between the lowest quartile (6%) and the highest quartile (15%) clinical sites. Univariate and multivariate analysis revealed that renal artery to stent-graft distance (P =.001) and proximal fixation length (P =.005) were significant predictors of migration, and that each millimeter increase in distance below the renal arteries increased risk for subsequent migration by 5.8% and each millimeter increase in proximal fixation length decreased risk for migration by 2.5%. Pre-implantation aortic neck length, neck diameter, degree of device oversizing, correct versus incorrect oversizing, device type (stiff vs flexible), placement of proximal extender cuffs at the original procedure, and post-procedure endoleak were not significant predictors of migration. Migration was treated with placement of extender modules in 23 patients and surgical conversion in 7 patients; 64 patients (68%) with migration have required no treatment. CONCLUSIONS: Stent-graft migration among patients treated in the AneuRx clinical trial appears to be largely related to low initial deployment of the device, below the renal arteries, and short proximal fixation length. Significant variation in migration rate among clinical sites highlights the importance of the technical aspects of stent-graft deployment. Advances in intraoperative imaging and deployment techniques that have been made since completion of the clinical trial facilitate precision of device placement below the renal arteries and should increase proximal fixation length. Whether this, together with increased iliac fixation length, will result in lower risk for migration remains to be determined in long-term follow-up studies.     

Iliac fixation length and resistance to in-vivo stent-graft displacement

PURPOSE: Migration of endovascular stent grafts has been related to the security of proximal device fixation to the aortic neck. This study evaluated the importance of iliac fixation in preventing longitudinal in vivo device displacement of a modular, externally supported stent graft. METHODS: Experimental ovine infrarenal aneurysms (n = 8) were treated with a fully supported, modular, bifurcated stent graft (AneuRx, Medtronic, Santa Rosa, Calif). Minimum iliac fixation length (1 cm) was used in four animals and iliac extender modules were used to achieve maximum iliac fixation in four animals. Suture anastomosis of bifurcated polyester grafts to the infrarenal aorta served as controls (n = 8). Aortic grafts were displaced in vivo by applying downward traction to a guidewire that was passed over the iliac flow divider and brought out both femoral arteries. The displacement force needed to initiate stent-graft migration was recorded and compared with the force needed to disrupt the sutured anastomosis. RESULTS: There was no difference in animal weight (88.8 +/- 2.5 kg vs 87.5 +/- 2.9 kg), aortic neck diameter (12.7 +/- 0.9 mm vs 13.4 +/- 1.1 mm), aortic neck length (23.2 +/- 0.9 mm vs 21.8 +/- 2.4 mm), experimental aneurysm size (24.7 +/- 1.1 mm vs 24.2 +/- 2.0 mm), or iliac artery diameter (9.0 +/- 1.5 mm vs 9.3 +/- 0.5 mm) among the groups. Iliac fixation length was 31.0 +/- 0.3 mm in the maximum iliac fixation group and 11 +/- 0.25 mm in the minimum fixation group (P < .0001). Peak displacement force to initiate migration was 30.2 +/- 5.5 N (range, 25 to 38) in animals with maximum iliac fixation compared with 18.1 +/- 3.7 N (range, 13 to 21) in those with minimum fixation (P = .01). The force needed to disrupt the control surgical anastomosis was 40.6 +/- 7.5 N (range, 31 to 50) (P < .01). CONCLUSIONS: Maximizing iliac fixation length increases the longitudinal in vivo force needed to displace a fully supported stent graft by 67%. This suggests that increasing iliac fixation length may reduce the long-term risk of migration in patients undergoing endovascular aneurysm repair.     

A comparison of AneuRx aortic cuff and zenith distal flare exclusion of common iliac artery ectasia for endovascular aneurysm repair

Stent-grafts are ideally terminated within the common iliac artery (CIA). However, CIA ectasia may require hypogastric artery occlusion, with stent-graft extension to the external iliac artery. Alternatively, the diameter of the distal stent-graft may be increased, or flared, to allow exclusion of the abdominal aortic aneurysm. This report details the authors' experience with this technique. Forty-one patients received bifurcated stent-grafts (BSG): 20 received an AneuRx device, and 21 received a Zenith device. CIA ectasia (diameter 15-25 mm) was treated with a distal flare of 2-4 mm greater than the CIA diameter. Patients were followed up with computed tomography scan at 1, 6, and 12 months. Statistical analysis was performed using ANOVA within groups and unpaired two-tailed t test between groups. A p value of < 0.05 was considered significant. Eight of 20 patients (40%) (11 CIA) received an AneuRx device and 13/21 (62%) (17 CIA) received a Zenith device, with a distal flare. Values are (n) mean (mm) +/- SE. There were no deaths, endoleaks, migrations, or conversions to open repair. Follow-up mean was 24.7 and 20.6 (range 15-28) months for AneuRx and Zenith groups, respectively. In comparing initial and 12-month CIA diameters, AneuRx grafts 20 +/-0.8 vs 21.5 +/-1.0 were not significantly different, p = 0.2, nor was the same comparison for Zenith, 17 +/-0.5 vs 19.1 +/-0.4, significant, p = 0.57. At a mean follow-up of 12 months, distal flare of iliac limbs with either AneuRx or Zenith devices affords a seal for CIA ectasia and/or aneurysms complicating EVAR.     

Aortic neck angulation predicts adverse outcome with endovascular abdominal aortic aneurysm repair

BACKGROUND: Significant aortic neck angulation may predispose to suboptimal outcome after endovascular abdominal aortic aneurysm (EAAA) repair. However, the definition of "significant" neck angulation and its correlation with adverse outcome are poorly characterized. METHODS: Prospectively collected data on 148 consecutive EAAA repairs performed between December 1995 and January 2001 were supplemented with retrospective review of charts and radiographs. Aortic neck angulation was measured from arteriograms or three-dimensional computed tomography scanning reconstructions. Patients were excluded (n = 24) if radiographs were unavailable for review. Because of a paucity of severe aortic neck angulation in other endograft groups, only patients treated with a modular bifurcated device (Medtronic) (n = 81) were included in the final analysis. Mean time from implantation was 26.6 +/- 9.2 months. RESULTS: The risk of a patient experiencing one or more adverse events was 70%, 54.5%, and 16.6% in those with severe (>or=60 degrees, n = 10), moderate (40 to 59 degrees, n = 11), and mild (<40 degrees, n = 60) aortic neck angulation, respectively (P =.0003). Adverse events included death within 30 days (20% vs 0%, P =.0007), acute conversion to open repair (20% vs 0%, P =.0007), aneurysm expansion (9.1% to 20% vs 1.7%, P =.034), device migration (20% to 30% vs 3.3%, P =.013), and type I endoleak (23.8% vs 8.3%, P =.033), all occurring with significantly greater incidence in patients with moderate or severe aortic neck angulation when compared with those with mild angulation, respectively. Aortic neck length and diameter, age, and medical comorbidities were not significantly different between groups. CONCLUSION: Aortic neck angulation appears to be an important determinant of outcome after EAAA repair. Although patients with mild angulation (<40 degrees) had favorable outcomes in this series, those with moderate (40 to 59 degrees) or severe angulation (>or=60 degrees) had a 54% to 70% risk of one or more adverse events. Importantly, these outcomes occurred in spite of an adequate length (>2 cm) of proximal aortic neck. On the basis of these data, great caution should be exercised in recommending EAAA repair for patients with aortic neck angulation >or=40 degrees.     

Explant analysis of AneuRx stent grafts: relationship between structural findings and clinical outcome

OBJECTIVE: We reviewed the structural findings of explanted AneuRx stent grafts used to treat abdominal aortic aneurysms, and relate the findings to clinical outcome measures. METHODS: We reviewed data for all bifurcated AneuRx stent grafts explanted at surgery or autopsy and returned to the manufacturer from the US clinical trial and worldwide experience of more than 33,000 implants from 1996 to 2003. Devices implanted for more than 1 month with structural analysis are included in this article. Explant results were analyzed in relation to cause of explantation and pre-explant evidence of endoleak, enlargement, or device migration. RESULTS: One hundred twenty explanted stent grafts, including 37 from the US clinical trial, were analyzed. Mean implant duration was 22 +/- 13 months (range, 1-61 months). Structural abnormalities included stent fatigue fractures, fabric abrasion holes, and suture breaks. The mean number of nitinol stent strut fractures per explanted device was 3 +/- 4, which represents less than 0.2% of the total number of stent struts in each device. The mean number of fabric holes per explanted device was 2 +/- 3, with a median hole size of 0.5 mm(2). Suture breaks were seen in most explanted devices, but composed less than 1.5% of the total number of sutures per device. "For cause" explants (n = 104) had a 10-month longer implant duration (P =.007) compared with "incidental" explants (n = 16). "For cause" explants had more fractures (3 +/- 5; P =.005) and fabric holes (2 +/- 3; P =.008) per device compared with "incidental" explants, but these differences were not significant (P =.3) when adjusted for duration of device implantation. Among clinical trial explants the number of fabric holes in grafts in patients with endoleak (2 +/- 3 per device) was no different from those without endoleak (3 +/- 4 per device; P = NS). The number of fatigue fractures or fabric holes was no different in grafts in clinical trial patients with pre-explant aneurysm enlargement compared with those without enlargement. Pre-explant stent-graft migration was associated with a greater number of stent strut fractures (5 +/- 7 per device; P =.04) and fabric holes (3 +/- 3 per bifurcation; P =.03) compared with explants without migration. Serial imaging studies revealed inadequate proximal, distal, or junctional device fixation as the probable cause of rupture or need for conversion to open surgery in 86% of "for cause" explants. Structural device abnormalities were usually remote from fixation sites, and no causal relationship between device findings and clinical outcome could be established. CONCLUSIONS: Nitinol stent fatigue fractures, fabric holes, and suture breaks found in explanted AneuRx stent grafts do not appear to be related to clinical outcome measures. Longer term studies are needed to confirm these observations.     

Long-term outcome after Talent endograft implantation for aneurysms of the abdominal aorta: a multicenter retrospective study

BACKGROUND: The development of newer-generation endografts for the endovascular treatment of abdominal aortic aneurysms has resulted in considerable improvements in clinical performance. However, long-term outcome data are still scarce. To assess long-term clinical and radiographic outcomes after use of the Talent stent graft, a retrospective analysis was performed that was based on 165 patients treated with this endograft in Germany between October 1996 and December 1998. METHODS: Data were collected according to the recommendation of the ad hoc committee for standardized reporting practices in vascular surgery and were evaluated statistically by using univariate and multivariate analyses. RESULTS: A total of 165 patients were treated with a Talent endograft in 9 German centers before December 31, 1998. Most were asymptomatic (94.5%), male (97.6%), and treated with a bifurcated graft (86.7%). Two patients (1.2%) died within 30 days, and 28 (17%) died during the follow-up period. The cause of death was aneurysm rupture in one case. Survival was 95.4% +/- 1.7% at 1 year, 89% +/- 2.6% at 2 years, 78.1% +/- 3.6% at 5 years, and 76.2% +/- 4.1% at 7 years. Patients classified as American Society of Anesthesiologists grade IV had a significantly lower survival rate (24.9%) than those classified as American Society of Anesthesiologists grade II and III (91.9% and 77.3%). During a mean follow-up period of 53.2 +/- 20.1 months (range, 1-84 months), 47 secondary procedures were performed in 31 patients (18.8%). Kaplan-Meier estimates showed a freedom from secondary intervention of 94.7% +/- 1.8%, 81.7% +/- 3.3%, and 77.4% +/- 3.6% at 1, 3, and 7 years, respectively. The reason for secondary treatment was endograft thrombosis in 10 patients (6.1%), persisting primary endoleak in 9 (5.5%), late secondary endoleak in 6 (3.6%), graft migration in 3 (1.8%), aneurysm rupture in 2 (1.2%), and graft infection in 1 (0.6%). Device migration (> or =10 mm) occurred in seven patients (4.2%). Other graft changes, such as graft kinking (n = 4; 2.4%), fracture of metallic stents (n = 2; 1.2%), erosion of the longitudinal bar (n = 2; 1.2%), or modular component separation (n = 1; 0.6%), were rare. Follow-up computed tomographic imaging revealed a decrease of the maximum aneurysm sac diameter (>5 mm) in 106 (64.2%) patients and an increase in 14 (8.5%) patients. The mean aneurysm diameter significantly decreased (P < .001). Of the factors recorded at baseline, only endoleaks showed a significant correlation with the risk of aneurysm increase during follow-up (P < .001). Adverse anatomy (neck diameter >28 mm, neck length <15 mm, and '5 patent aortic branches) did not adversely influence the aneurysm shrinkage rate, the risk for a secondary procedure, or the clinical success rate. A significantly higher rate of clinical success (P < .05) was observed in patients older than 65 years of age. CONCLUSIONS: Implantation of the Talent endograft device is a safe and effective alternative to open surgery for exclusion of abdominal aortic aneurysm. In comparison with first-generation grafts, the device showed superior durability for as long as 5 to 7 years after implantation. Even if prototypes of the Talent device were implanted in this study, the graft was also successfully used in most patients, even in those with adverse anatomy. Because improvements of the endograft have been made to address connecting bar breaks, a lower incidence of graft limb occlusion can be expected in the future.     

Endograft migration one to four years after endovascular abdominal aortic aneurysm repair with the AneuRx device: a cautionary note

BACKGROUND: Positional stability of the endograft is essential for long-term durability after endovascular abdominal aortic aneurysm repair (EAR). However, the cumulative risk of delayed endograft migration has been sparsely reported. METHOD: A total of 91 patients studied underwent EAR with the AneuRx endograft with a minimum 1 year from implantation. Data from a prospective database were assessed for proximal endograft migration, defined as > or = 5 mm change from the initial endograft position. Multiple anatomic characteristics were also examined. Sixty-nine patients were alive, with complete follow-up at 1 year, with a mean time from implantation of 33.2 +/- 1.1 months. Data are mean +/- SEM. RESULTS: Endograft migration occurred in 15 patients, giving a cumulative event rate of 7.2% (5/69) at 1 year, 20.4% (10/49) at 2 years, 42.1% (8/19) at 3 years, and 66.7% (2/3) at 4 years post-EAR (P =.01). Although the initial aortic neck diameter did not differ between the groups (21.5 +/- 0.6 mm vs 21.8 +/- 0.3 mm, P =.61), significant (P <.05), late aortic neck enlargement was seen in patients with migration (25.0 +/- 1.6 mm, 26.2 +/- 1.2 mm, and 27.0 +/- 1.0 mm at 1,2, and 3 years, respectively) but not in nonmigrators. Regression analysis demonstrated a statistically significant (P <.05) correlation between endograft oversizing and late aortic neck dilation. Overall migration risk was 29.2% in patients oversized >20% and 18.6% in patients oversized < or = 20%. Aortic neck angulation (23.4 +/- 6.6 degrees vs 23.5 +/- 3.3 degrees, P =.99), aortic neck length (25.9 +/- 2.5 mm vs 27.0 +/- 1.6 mm, P =.74), initial endograft/aortic neck overlap (18.6 +/- 2.6 mm vs 19.4 +/- 1.4 mm, P =.80) and size of abdominal aortic aneurysm (55.5 +/- 1.5 mm vs 54.9 +/- 1.4 mm, P =.84) were similar between migrators and nonmigrators, respectively. Secondary endovascular treatment with aortic cuffs was required in five patients with device migration. CONCLUSIONS: Device migration after EAR with the AneuRx endograft occurred with significant frequency, the incidence of which increased with the length of follow-up. Late aortic neck dilation was significantly associated with migration. Oversizing of the endograft of >20% may accelerate this late aortic neck dilation. However, the etiologies of endograft migration were likely multifactorial, as the majority (8/15) of patients experiencing migration were oversized <20%. Although endovascular repair of these migrations is usually possible, the long-term durability of these secondary procedures is unknown. Careful surveillance for this endograft failure mode must be an essential component of post-EAR follow-up.     

Aorto uni-iliac modification of a bifurcated stent graft for endovascular aneurysm repair: Expanding the versatility of a modular device

As endografting technology advances, anatomical constraints limiting access and deployment have become less of a burden. While unsuitable candidates for endografting exist, these patients are becoming less frequent. To broaden the applicability of endovascular abdominal aortic aneurysm repair (EVAR), we have modified the bifurcated AneuRx device into a unilimb modular prosthesis, by placing an aortic extender cuff across the flow divider, thus excluding its contralateral limb. This technique was used with success in 3 groups of patients: with occlusion of 1 iliac artery, with a nontraversable iliac stenosis, or with a small calcific aortic bifurcation. In these patients, anatomy can make it difficult, if not impossible, to place a bifurcated stent graft. Whether as a planned preoperative procedure or as a ;;bail-out' maneuver, this procedure has been successful in avoiding open surgical conversion.     

Midterm pivotal trial results of the Talent Low Profile System for repair of abdominal aortic aneurysm: analysis of complicated versus uncomplicated aortic necks

OBJECTIVE: This study was undertaken to determine whether a complicated aortic neck is associated with unfavorable outcome after abdominal aortic aneurysm (AAA) endografting. METHODS: In a prospective pivotal clinical trial, 237 consecutive patients underwent implantation of the bifurcated Talent Low Profile System. Patients were divided into 2 groups, those with complicated aortic necks (short, <15 mm; very short, < or =10 mm; dilated, >28 mm; angulated, >45 degrees; calcified; and thrombus-lined) versus those with uncomplicated neck anatomy. Major outcome parameters included procedure time, operative blood loss, transfusion requirements, volume of contrast medium used during the implant procedure, endoleaks, migration, limb patency, AAA regression, conversion to open repair, morbidity, and mortality. Mean follow-up was 620.5 days. RESULTS: Overall, 32% of aortic necks were short, 19% were very short, 20% were dilated, 18% were calcified, 8.5% were thrombus-lined, and 19.9% were angulated. Thirty percent and 70% of patients, respectively, were stratified to the uncomplicated and complicated groups ( P < .01. Procedure time, operative blood loss, transfusions, volume of contrast medium used in the implant procedure, migration, endograft patency, AAA sac regression, conversion to open repair, and mortality were not significantly different in necks with complicated versus uncomplicated anatomy. At 21 months, sacs were regressing or stable in 98% (complicated) versus 96% (uncomplicated). Primary graft limb patency was 100% in both groups. The endoleak rate was 4.3% (complicated) versus 17% (uncomplicated) at 18 months, but this difference was not statistically significant. Adverse renal events, however, occurred in 27.5% (complicated) versus 13.6% (uncomplicated; P = .04). CONCLUSIONS: Complicated aortic neck is not associated with unfavorable outcome at midterm follow-up after AAA endografting. However, statistically more adverse renal events occur in patients with complicated neck anatomy.     

Aortic Neck Attachment Failure and the AneuRx Graft: Incidence, Treatment Options, and Early Results

Some investigators have reported that proximal attachment failure is a long-term complication of endovascular abdominal aortic aneurysm repair (EVAR) with the AneuRx (Medtronic, Santa Rosa, CA) device. We evaluated the need for an intervention in patients with suboptimal proximal fixation as well as the feasibility and early success of a variety of treatment strategies. From October 1999 to October 2003, we performed 365 EVARs using the AneuRx graft. At a mean follow-up of 23.7 ± 14.8 months, 20 patients (5.5%) with suboptimal outcomes (14 with a type I endoleak, one with a type III endoleak, and 5 with an inadequate seal zone <1 cm) were considered for treatment. Characteristics of each patient’’s aortic neck anatomy that could be associated with proximal attachment failure were evaluated. Eighteen patients (90%) underwent successful treatment (9 AneuRx cuffs, 6 Talent cuffs, 5 aortic stents, one redo endograft, and two surgical conversions) without major perioperative complications, one patient had a persistent type I endoleak despite endovascular treatment, and one patient refused treatment, ultimately leading to aneurysm rupture. There have been no further endoleaks or graft migrations noted since the secondary intervention at a mean follow-up of 13.9 ± 11.8 months. In our experience, proximal attachment failure associated with the AneuRx graft is relatively uncommon and usually associated with unfavorable neck anatomy. Despite this, most cases are treatable by endovascular means. Long-term follow-up is needed to assess the ultimate frequency of these combined device reconstructions.Presented at the spring meeting of the Peripheral Vascular Surgery Society, Anaheim, CA, June 5, 2004.     

Does hostile neck anatomy preclude successful endovascular aortic aneurysm repair?

OBJECTIVES: Poor outcomes have been reported with endovascular aneurysm repair (EVAR) in patients with hostile neck anatomy. Unsupported endografts with active fixation may offer certain advantages in this situation. We compared EVAR results using the Ancure (Guidant) endograft in patients with and without hostile neck anatomy. METHODS: Records of EVAR patients from October 1999 to July 2002 at a tertiary care hospital were retrospectively reviewed from a division database. Patients with elective open abdominal aortic aneurysm (AAA) repair during the same period were reviewed to determine those unsuitable for EVAR. Hostile neck anatomy, assessed by computer tomography (CT) scans and angiograms, was defined as one or more of the following: (1) neck length 3 mm, (3) >2-mm reverse taper within 1 cm below the renal arteries, (4) neck thrombus > or =50% of circumference, and (5) angulation > or =60 degrees within 3 cm below renals. RESULTS: Three hundred and twenty-two patients underwent EVAR with an average follow-up of 18 months. Patients in Phase II trials (n = 41), repaired with other graft types (n = 48), or without complete anatomic records (n = 27) were excluded. Demographics and co-morbidities were similar in the 115 good-neck (GN) and 91 bad-neck (BN) patients except for age (mean, 72.9 years GN vs 75.7 BN; P = 0.13), gender (11% female GN vs 22% BN; P =.04); neck length (mean, 21.8 mm GN vs 14.4 mm BN: P <.001), and angulation (mean, 22 degrees GN vs 40 degrees BN; (P <.001). Perioperative mortality (0 GN vs 1.1% BN), late mortality (5.2% GN vs 4.4% BN), all endoleaks (19.1% GN vs 17.6% BN), proximal endoleaks (0.8% GN vs 2.1% BN), and graft migration (0 for both groups) did not reach statistical significance. Neck anatomy precluded EVAR in 106 of 165 (64%) patients with open AAA. CONCLUSIONS: Unsupported endografts with active fixation can yield excellent results in treating many medically compromised patients with hostile neck anatomy. Nonetheless, an unsuitable neck remains the most frequent cause for open abdominal AAA.     

Influence of endograft oversizing on device migration, endoleak, aneurysm shrinkage, and aortic neck dilation: results from the Zenith Multicenter Trial

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 < or =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 < or =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 approximately 14-fold increase in device migration (>5 mm) at 12 months and with a approximately 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.     

Predicting iliac limb occlusions after bifurcated aortic stent grafting: anatomic and device-related causes

OBJECTIVE: Graft limb occlusion may complicate endovascular abdominal aortic aneurysm repair. The precise etiologic factors that contribute to the development of these graft limb thromboses have not been defined. We evaluated our experience with bifurcated aortic endografts to determine factors that may predict subsequent limb thrombosis. The management of the thrombosed limbs and the results after treatment were also investigated. METHODS: During a 4-year period, 351 patients with aortic aneurysms underwent treatment with bifurcated endografts (702 graft limbs at risk). These 351 bifurcated devices included AneuRx (Medtronic, Minneapolis, Minn; n = 35), Ancure (Guidant, Menlo Park, Calif; n = 8), Gore (W.L. Gore & Associates, Sunnyvale, Calif; n = 25), Talent (World Medical, Sunrise, Fla; n = 255), Teramed (Teramed, Minneapolis, Minn; n = 10), and Vanguard (Boston Scientific Vascular, Natick, Mass; n = 18). Details regarding the type of device, mechanism of deployment, and aortoiliac artery anatomy were collected prospectively and analyzed. Graft limbs were analyzed for diameter, use of additional endograft iliac extensions, deployment in the external iliac artery, and endograft to vessel oversizing. Follow-up included physical examination, duplex ultrasonography, and spiral computed tomographic scans at 1 month, 6 months, and 12 months and annually thereafter. The follow-up period ranged from 2 to 54 months, with a mean follow-up period of 20 months. RESULTS: Twenty-six of 702 limbs (3.7%) had an occlusion develop. The risk of limb thrombosis was associated with a smaller limb diameter. Mean graft limb diameter was 14 mm in the occluded population, and patent limbs had a mean diameter of 16 mm. Thrombosis occurred in 16 of 291 limbs (5.5%) that were 14 mm or less and in 10 of 411 limbs (2.4%) that were greater than 14 mm (P =.03). Extension of a graft to the external iliac artery was performed in 96 of the 702 limbs. Eight of these 96 limbs (8.3%) had thrombosis develop as compared with 18 of 606 (3.0%) that extended to the common iliac artery (P =.01). No significant association was present between limb thrombosis and the contralateral or ipsilateral side of a device, the configuration of the iliac graft limb end (closed web, open web, or bare spring), or the degree of iliac graft limb oversizing. AneuRx, Ancure, Vanguard, and Talent grafts each sustained limb occlusions, with no occlusions seen among the Gore and Teramed devices. No significant increased risk of graft limb thrombosis was observed in unsupported grafts (1/16; 6.3%) versus supported grafts (25/686; 3.6%; P = not significant). Thromboses occurred between 1 day and 23 months after surgery. Thirteen of the 26 thromboses (50%) occurred within 30 days of surgery. Presenting symptoms were mild to moderate claudication in eight patients (30.8%), severe claudication in 16 patient (61.5%), and paresthesia and rest pain in two patients (7.7%). Eighteen of 26 patients (69.2%) eventually needed intervention to reestablish flow to the occluded limb, including thrombolysis and stenting in two patients (7.7%), axillary femoral bypass in one patient (3.8%), femoral-femoral bypass in 13 patients (50.0%), and axillary-bifemoral bypass in two patients (7.7%). All patients with mild to moderate symptoms under observation had improvement in symptoms with no further interventions necessary. All revascularizations were successful in relieving symptoms. CONCLUSION: Graft limb occlusion is a recognized complication of endovascular treatment of abdominal aortic aneurysms that may be associated with smaller graft limb diameter and extension to the external iliac artery. Occlusions usually necessitate additional intervention for resolution of ischemic symptoms. The use of small diameter grafts should be avoided when possible to reduce the risk of graft limb occlusions.     

Aortic Aneurysm Sac Shrinkage after Endovascular Repair Is Device–dependent: A Comparison of Zenith and AneuRx Endografts

Aneurysm sac shrinkage after endovascular aneurysm repair (EAR) provides objective evidence of successful aneurysm exclusion and absence of endotension. Attainment of this outcome parameter may be device-dependent. In this study, 169 patients underwent EAR with an AneuRx (n = 118) or Zenith (n = 51) endograft at a single institution. A prospectively maintained database was examined for significant changes in aneurysm sac diameter (> or = 5 mm) on the basis of computed tomography (CT) measurements at 6 and 12 months follow-up. Significant aneurysm sac shrinkage (> or = 5 mm) occurred in 73.1 % (19/26) vs. 43.1% (28/65) of patients in the Zenith and AneuRx groups, respectively, at 12 months (p = 0.03). At 6 months follow-up, sac shrinkage rates were 51.4% (19/37) vs. 25.8% (16/62) in the Zenith and AneuRx groups, respectively (p = 0.04). Mean reduction of sac diameter at 12 months was -7.6 +/- 1.6 mm vs. -3.5 +/- 0.8 mm in the Zenith and AneuRx groups, respectively (p = 0.01). There was a trend toward fewer Type I and III endoleaks at 1 month in the Zenith group (0 vs. 8.3%) that did not achieve statistical significance (p = 0.067). The presence of any endoleak (> or = 1 month) was associated with reduced 12 month shrink rates from 47.1% (25/51) to 28% (4/14) in the AneuRx group (p = 0.35) and from 77.3% (17/22) to 50% (2/4) in the Zenith group (p = 0.25). Patients treated with the Zenith endograft demonstrated a significantly higher rate and amount of aneurysm sac shrinkage than patients treated with an AneuRx device. Endoleaks appeared to negatively influence shrink rates with both endografts.     

The AneuRx modular endograft device for the treatment of abdominal aortic aneurysms. Overview of 7 years of clinical use

Open surgical repair of abdominal aortic aneurysms (AAAs) has been performed for over 40 years now with good results. However, the procedure continues to be high-risk with numerous potential complications. The AneuRx modular bifurcated endograft was one of the first to be tested to exclude AAAs via an endovascular approach. Data from multiple clinical trials show that treatment of AAAs with the AneuRx device is comparable to open repair with regards to mortality and may have improved short-term and long-term morbidities rates. The following review discusses clinical use of the AneuRx stent graft system from the initial clinical trial in 1996 to its current commercial use.