Intraoperative proximal endoleaks during AAA stent-graft repair: evaluation of risk factors and treatment with Palmaz stents

Ultrasound elastography to quantify average percent pressure-normalized strain reduction associated with different aortic endografts in 3D-printed hydrogel phantoms

Objective

Strain has become a viable index for evaluating abdominal aortic aneurysm stability after endovascular aneurysm repair (EVAR). In addition, literature has shown that healthy aortic tissue requires a degree of strain to maintain homeostasis. This has led to the hypothesis that too much strain reduction conferred by a high degree of graft oversizing is detrimental to the aneurysm neck in the seal zone of abdominal aortic aneurysms after EVAR. We investigated this in a laboratory experiment by examining the effects that graft oversizing has on the pressure-normalized strain (ε ρ + ¯ /pulse pressure [PP]) reduction using four different infrarenal EVAR endografts and our ultrasound elastography technique. Approximate graft oversizing percentages were 20% (30 mm phantom-graft combinations), 30% (28 mm phantom-graft combinations), and 50% (24 mm phantom-graft combinations).

Methods

Axisymmetric, 10% by mass polyvinyl alcohol phantoms were connected to a flow simulator. Ultrasound elastography was performed before and after implantation with the four different endografts: (1) 36 mm polyester/stainless steel, (2) 36 mm polyester/electropolished nitinol, (3) 35 mm polytetrafluoroethylene (PTFE)/nitinol, and (4) 36 mm nitinol/polyester/platinum-iridium. Five ultrasound cine loops were taken of each phantom-graft combination. They were analyzed over two different cardiac cycles (end-diastole to end-diastole), yielding a total of 10 maximum mean principal strain (ε ρ + ¯ ) values.ε ρ + ¯ was divided by pulse pressure to yield pressure-normalized strain (ε ρ + ¯ /PP). An analysis of variance was performed for graft comparisons. We calculated the average percentε ρ + ¯ /PP reduction by manufacturer and percent oversizing. These values were used for linear regression analysis.

Results

Results from one-way analysis of variance showed a significant difference inε ρ + ¯ /PP between the empty phantom condition and all oversizing conditions for all graft manufacturers (F(3, 56) = 106.7 [graft A], 132.7 [graft B], 106.5 [graft C], 105.7 [graft D], P < .0001 for grafts A-D). There was a significant difference when comparing the 50% condition with the 30% and 20% conditions across all manufacturers by post hoc analysis (P < .0001). No significant difference was found when comparing the 20% and 30% oversizing conditions for any of the manufacturers or when comparingε ρ + ¯ /PP values across the manufacturers according to percent oversize. Linear regression demonstrated a significant positive correlation between the percent graft oversize and the all-graft average percentε ρ + ¯ /PP reduction (R 2  = 0.84, P < .0001).

Conclusions

This brief report suggests that a 10% increase in graft oversizing leads to an approximate 5.9% reduction inε ρ + ¯ /PP on average. Applied clinically, this increase may result in increased stiffness in axisymmetric vessels after EVAR. Further research is needed to determine if this is clinically significant.

Conical Aortic Neck as a Predictor of Outcome after Endovascular Aneurysm Exclusion: Midterm Results

BACKGROUND

Conical neck may affect endovascular aneurysm repair (EVAR) outcomes. The aim of this study was to present EVAR neck adverse events [endoleak type Ia (ET Ia) and graft migration], in patients with conical neck morphology compared to patients with non-conical necks. An additional analysis of the factors that may affect neck adverse events in patients with conical necks, during the first postoperative year, was executed.

METHODS

A retrospective analysis of prospective data was conducted, including patients that underwent elective EVAR, between 2017 and 2019. All patients completed the clinical and imaging follow-up of the initial 12 months. Regarding imaging, all cases underwent computed tomography angiography (CTA), preoperatively, at the 1st and 12th month of follow-up. Preoperative and postoperative aneurysm anatomic characteristics (supra-renal and infra-renal aortic diameters, aneurysm diameter, neck angle, thrombus, and calcification) were recorded. Proximal neck was defined as the infrarenal aortic segment, with a diameter less than 30 mm. Conical neck was any neck with a diameter increase ≥2 mm per cm of length (from outer-to-outer aortic wall). The proximal 15 mm of the neck length were considered the zone of endograft sealing. Migration was any ≥10 mm caudal movement of the endograft, relative to its position detected at the CTA of the first month. Neck adverse events were defined as the composite event of ET Ia and migration.

RESULTS

The cohort included 150 patients; 66 (44%) presented conical neck morphology. No significant difference was detected regarding the preoperative anatomic characteristics between the conical and non-conical groups. Only distal (15 mm) neck diameter was wider in the conical group (P < 0.001). Supra-renal active fixation was used in 63.3% of the total cohort; 59.5% in patients with non-conical necks and 68.2% in patients with conical morphology (P = 0.275). Graft oversizing was 18.2% and 18.7% in the non-conical and conical group, respectively (P = 0.248). Oversizing >20% was equal between groups [37.8% vs. 33.3%% (P = 0.608) while oversizing ≥30% was more common among patients with conical necks (3.5% vs. 10.6%, P < 0.001, 3.2 odds ratio, 95% confidence interval: 0.79, 12.91). Regarding ET Ia and migration, no difference was recorded between the groups. In a subanalysis among patients with conical necks, a lower graft migration rate was detected among patients with higher oversizing rate (P = 0.037).

CONCLUSIONS

EVAR may offer similarly good midterm outcomes in patients with conical and non-conical neck anatomy. An oversizing to the higher suggested rate may be preventive of graft migration during the first postoperative year in necks with conical morphology. Aggressive oversizing (>20%) do not offer any benefit regarding the prevention of adverse events among patients with conical necks.

Early Clinical Outcomes of the Active Seal Technology of the AFX Endovascular Aortic Aneurysm System With the VELA Cuff for Patients With a Conical Proximal Neck

PURPOSE

To evaluate the efficacy of the Active Seal technology employed in the AFX endovascular aortic aneurysm system (AFX), during endovascular aneurysm repair (EVAR) in patients with abdominal aortic aneurysms (AAAs) having a conical proximal neck.

MATERIALS AND METHODS

A retrospective analysis of the EVAR for AAA with a conical proximal neck using the AFX was performed at 17 Japanese hospitals between January 2016 and August 2020. The conical proximal neck was defined as a cone-shaped proximal neck, with more than 10% diameter increase within a 15 mm length at the proximal landing zone. All anatomical analyses were performed in the core laboratory, and cases with parallel walls within the proximal neck adequate for the landing zone were excluded from the study.

RESULTS

This study included 53 patients, but only 39 patients (mean age, 76.6 ± 6.7 years; 87.0% males; mean aneurysm diameter, 52.0 ± 8.0 mm) were analyzed after being characterized as having a pure conical neck by the core laboratory. The mean proximal neck diameters at the lower renal artery and proximal edge of the aneurysm were 20.0 ± 2.9 mm and 27.5 ± 4.9 mm, respectively. The mean proximal neck length was 21.5 ± 6.0 mm. Instructions for use violations other than the conical neck were observed in 15 patients (38.5%). The VELA cuff was used in all cases; however, additional proximal cuff was required in 9 more cases (23.1%). The Active Seal technology was able to significantly extend the proximal sealing zone from 21.5 ± 6.0 to 26.0 ± 12.2 mm (p = .047). Thirty-six patients completed the 12-month follow-up (one patient was lost to follow-up, and 2 patients died from causes unrelated to the aneurysm), and there were no type-1a and 3 endoleaks with only one reintervention (2.6%) related to type 1b endoleak in the 12-month period. Furthermore, there was no significant enlargement of the proximal neck diameter at 12 months (at 1 month: 20.6 ± 3.4 mm and at 12 months: 21.3 ± 3.8 mm; p = .420).

CONCLUSION

The Active Seal technology of the AFX significantly extended the proximal seal zone and no type-1a endoleak and proximal neck dilation was observed in patients with conical proximal neck at 12 months.

Open repair versus evar with parallel grafts in patients with juxtarenal abdominal aortic aneurysm excluded from fenestrated endografting

BACKGROUND

We compared the outcomes of open surgical repair (OSR) versus EVAR with parallel graft technique (PG) in patients with juxtarenal abdominal aortic aneurysm (JAAA) excluded from fenestrated endovascular aortic repair (FEVAR) due to clinical, anatomical, technical or manufacturing time reasons.

METHODS

A single-center analysis of consecutive patients who underwent elective and urgent (within 24-48 hours) repair of JAAA from January 2010 to January 2019 was performed. Two groups were compared: patients excluded from FEVAR and respectively treated by OSR or by PG for JAAA. Perioperative clinical, anatomic and operative data were collected in a dedicated database. The endpoints were primary technical success, changes in renal function, early and long-term mortality, freedom from aortic related reinterventions (ARRs) and aortic related mortality (ARM).

RESULTS

118 consecutive patients were treated for JAAA, 32 of them (27.1%) with FEVAR. 86 patients were enrolled in the study (OSR group=61; PG group= 25). The mean age was 77.4 ± 6.5 years for PG group and 71.1 ± 6.7 years for OSR group (p=.0001); the average comorbidity score of the Society for Vascular Surgery was higher for patients treated by PG (10.2 ± 4.8 vs 5.5 ± 0.4, p=.0001), with no differences for hypertension and renal score. After propensity score matching, 42 patients (OSR=27 ; PG=15) without differences in the preoperative risk factors were selected. Conical shape and neck mural thrombus were respectively more represented in the OSR group (95.1% vs 56.0%; 63.9% vs 36.0%). Aortic clamp site was supraceliac for 12 patients (19.7%), suprarenal for 21 (34.4%) and trans-renal for 28 patients (45.9%). In the PG group, 16 patients (64%) were treated with a single renal chimney. Primary technical success was similar in the two groups (100.0% vs 92.0%, p=.08), with an higher rate of procedure achieved by assisted technical success for the PG group after propensity score matching analysis (20.0% vs 0%, p=.04). Deterioration of renal function occurred for both groups of patients, with a significant creatinine increasing 12 months after surgery in the PG group compared with OSR group (1.72 ± 0.66 vs 1.18 ± 0.40, p=.006). Multiple logistic regression shows no independent predictor of peri-operative medical complication among demographics and pre-operative relevant clinical factors between the two cohorts. No difference in terms of early mortality was observed between the groups (1.6 % vs 0%, p=1.00). At 5 years, overall survival was lower for patients treated by PG (53.5% vs 70.2%, p=.007), such as freedom from ARRs (64.6 vs 90.5%, p=.03). Freedom from ARM at 5 years did not show significant differences among the two groups (100% vs 98.4%, p=1.00).

CONCLUSIONS

PG represents a feasible procedure for patients excluded from FEVAR due to clinical, anatomical, technical or device manufacturing time reasons, ensuring low rates of ARM. However, ARRs during the follow-up remain the Achilles heel of this technique. OSR is still the most durable procedure in the endovascular era, allowing the treatment of proximal "hostile necks" with low rates of reoperation and a similar impact on the renal function compared to PG.

Evolving Concepts, Management, and Treatment of Type 1 Endoleaks after Endovascular Aneurysm Repair

Over the past 20 years, there has been tremendous progress in endovascular aneurysm repair techniques and devices. The application of new third- and fourth-generation devices (from 2003 onward) has led to changes in the incidence and management of endoleaks. This comprehensive review aims to outline the most recent concepts with respect to pathophysiology/risk factors and management of Type 1 endoleaks.

Conservative management of type 1A endoleaks at completion angiogram in endovascular repair of infra-renal abdominal aortic aneurysms with current generation stent grafts

Purpose

Proximal type 1A endoleaks on completion intra-operative angiography are not infrequently seen following endovascular abdominal aneurysm repair (EVAR). The natural course of these leaks is not well established. We sought to determine the rate of spontaneous resolution and a conservative treatment approach to these endoleaks.

Methods

All cases involving endovascular repairs of infra-renal abdominal aortic aneurysms resulting in proximal type 1A endoleak on final intra-operative completion angiography were retrospectively reviewed from 1 April 2010 and 30 March 2015. Demographic, pre and post-procedural imaging, and clinical outcomes were reviewed. Summarizing descriptive statistics are reported.

Results

Of the 337 patients who underwent an EVAR, 24 patients (7.1%) had a proximal type 1A endoleak on final intra-operative angiography. Twenty-two of 24 patients (92%) with proximal type 1A endoleaks had spontaneous resolution on follow-up imaging without any intervention, while two (8%) patients had a persistent endoleak. One of these patients required intervention. The median follow-up for patients with resolved endoleaks was 2.5 years vs. 4 and 6 years, respectively, for patients that did not resolve spontaneously.

Conclusion

A conservative approach may be used in the management of patients with proximal type 1A endoleaks on completion angiography once maximum proximal seal was achieved intra-operatively as the vast majority of these leaks spontaneously seal.

Severe infolding of fenestrated-branched endovascular stent graft

Infolding of a fenestrated-branched stent graft is an infrequent complication due to excessive oversizing. We report the case of an 89-year-old man who underwent a four-vessel fenestrated-branched endovascular aortic repair for a pararenal aortic aneurysm. Computed tomography angiography revealed severe infolding across the mesenteric-renal vessels. The patient was treated by angioplasty and placement of Palmaz stent. Cone-beam computed tomography confirmed patent visceral vessels with resolution of the infolding. This case illustrates an uncommon complication that can be prevented by modifications in the stent design and by immediate assessment using intraoperative cone-beam computed tomography.

Endovascular Aneurysm Repair in Patients with Conical Neck Anatomy

PURPOSE

Cone shape neck is regarded as non-instruction for use (IFU) in most commercial stent graft. However, in real practice, liberal application of endovascular aneurysm repair (EVAR) for outside of IFU happens. We investigate non-adherence to conical neck anatomy in terms of early aneurysmal exclusion results.

MATERIALS AND METHODS

From January 2010 to December 2013, 105 patients with abdominal aortic aneurysm (AAA) underwent EVAR in Daegu Catholic University Medical Center. Among them, 38 patients (36.2%) had AAA with conical neck. We investigated the clinical characteristics of patients and the details of conical neck. We also analyzed the clinical results, such as endoleak, migration, procedure failure, perioperative mortality, and admission duration between conical neck and non-conical neck.

RESULTS

The maximum diameter of AAA was larger (60.95 mm vs. 52.68 mm, P=0.016) and the infrarenal neck length was shorter (25.07 mm vs. 38.13 mm, P=0.000) in conical neck group. During the procedure, type Ia endoleak occurred more in conical neck group (23.7% vs. 6.0%, P=0.013) and it could be successfully solved with additional adjunctive treatments, such as balloon or Palmaz stent. Although there was no statistical significance, mortality was higher and admission duration was longer in the conical neck (15.8% vs. 6.0%, 16.62±13.12 days vs. 13.03±13.13 days). Mean follow-up duration was 319.2±366.45 days. Successful aneurysmal exclusion was achieved.

CONCLUSION

The presence of conical neck may not be a contraindication for EVAR. However, conical neck requires careful observation for additional adjunctive treatments because it increases the risk of type Ia endoleak.

Treatment of a Late-Appearing Proximal Type-1 Endoleak After Ancure Graft with an AneuRx Cuff

The authors describe the case of a patient who developed a type-1 proximal endoleak 10 months after Ancure stent graft placement, despite the lack of stent migration or measurable neck dilatation. The patient had been under observation for a persistent type-2 endoleak and was noted to have an increase in his aneurysm size. The use of an uncovered stent was unsuccessful, and he required a covered proximal extension cuff. This led to a resolution of the endoleak. Implications in terms of surveillance and possible etiologies are discussed.

A 15-Year Single-Center Experience of Endovascular Repair for Elective and Ruptured Abdominal Aortic Aneurysms

Purpose: To evaluate the differences in technical outcomes and secondary interventions between elective endovascular aneurysm repair (el-EVAR) procedures and those for ruptured aneurysms (r-EVAR). Methods: Of the 906 patients treated with primary EVAR from September 1998 until July 2012, 43 cases were excluded owing to the use of first-generation stent-grafts. Among the remaining 863 patients, 773 (89.6%) patients (mean age 72 years; 697 men) with asymptomatic or symptomatic abdominal aortic aneurysms (AAAs) were assigned to the el-EVAR group; 90 (10.4%) patients (mean age 73 years; 73 men) were assigned to the r-EVAR group based on blood outside the aortic wall on preoperative imaging. The primary study outcome was technical success; secondary endpoints, including freedom from secondary interventions and late survival, were examined with Kaplan-Meier analyses. Results: At baseline, r-EVAR patients had larger aneurysms on average (p<0.001) compared to el-EVAR patients. Technical success was comparable (p=0.052), but there were more type Ia endoleaks at completion angiography in the r-EVAR group (p=0.038). As anticipated, more patients died in the first month in the r-EVAR group (18.9% vs 2.2% el-EVAR, p<0.001). At 5 years, there was an overall survival of 65.1% for the el-EVAR patients vs 48.1% in the r-EVAR group (p<0.001). The freedom from AAA-related mortality was 95.7% for el-EVAR and 71.0% for r-EVAR (p<0.001). Five-year freedom from type I/III endoleaks was significantly lower in the r-EVAR group (78.7% vs 90.0%, p=0.003). Five-year freedom from secondary intervention estimates were not significantly different (el-EVAR 84.2% vs r-EVAR 78.2%, p=0.064). Conclusion: Within our cohort of primary EVAR patients, r-EVAR cases showed comparable stent-graft–related technical outcome. Although there was a higher incidence of type Ia endoleaks on completion angiography in the r-EVAR group, the overall secondary intervention rate was comparable to el-EVAR.

Improvement in Proximal Aortic Endograft Fixation: An Experimental Study Using Different Stent-Grafts in Human Cadaveric Aortas

Purpose:

To compare the proximal fixation characteristics of different types of stent-grafts (SG) and the adjunctive effect of a proximally placed Palmaz stent.

Methods:

Human cadaveric aortas were obtained at autopsy and cut into 30 aortic segments. Appropriately oversized (10% to 20%) commercial stent-grafts (Zenith, Ancure, Excluder, Talent) and 4 configurations of homemade Palmaz-based stent-grafts (polytetrafluoroethylene or polyester coverings each with no uncovered proximal edge or a 20-mm bare section of stent) were implanted 20 mm into an aortic segment and balloon dilated. Each segment was placed in an experimental apparatus to measure the dislodgment force. Bare Palmaz stents were used to reinforce the proximal fixation of the commercial stent-grafts, and the measurements were repeated. Manual anastomoses were made and their dislodgment force tested for comparison.

Results:

The median dislodgment force ranged from 6.5 N for the Excluder to 26.5 N for the Zenith (8.0 N for the Talent, 11.8 N for the Ancure, and 8.1 to 10.7 N for the various Palmaz stent-graft designs). There was no significant difference between the Zenith and the Ancure groups or between the Excluder and the Talent groups. However, the Zenith and Ancure devices required significantly higher (p = 0.0004) force (∼25%) to displace them than the other stent-grafts tested. With the Palmaz stent added to the proximal attachment site, the median dislodgment force for the different commercial endografts was significantly improved for all devices (p < 0.03): 34% for the Zenith device, 69% for the Ancure, 73% for the Talent, and 80% for the Excluder endoprosthesis.

Conclusions:

The Zenith stent-graft had the best resistance to dislodgment. An additional Palmaz stent placed at the proximal attachment site greatly improves endograft fixation regardless of the type of stent-graft. For complex aneurysm necks or for intraoperative type I endoleak management, an adjunctive Palmaz stent could be used.

Endovascular aneurysm repair: current and future status

Endovascular aneurysm repair has rapidly expanded since its introduction in the early 1990s. Early experiences were associated with high rates of complications including conversion to open repair. Perioperative morbidity and mortality results have improved but these concerns have been replaced by questions about long-term durability. Gradually, too, these problems have been addressed. Challenges of today include the ability to roll out the endovascular technique to patients with adverse aneurysm morphology. Fenestrated and branch stent-graft technology is in its infancy. Only now are we beginning to fully understand the advantages, limitations, and complications of such technology. This paper outlines some of the concepts and discusses the controversies and challenges facing clinicians involved in endovascular aneurysm surgery today and in the future.

Outcomes of Endovascular Abdominal Aortic Aneurysm Repair in Patients with Hostile Neck Anatomy

PURPOSE

The principal anatomic contraindication to endovascular aneurysm repair (EVR) is an unfavorable proximal aortic neck. With increasing experience, a greater proportion of patients with unfavorable neck anatomy are being offered EVR. This study aimed to evaluate outcomes in patients with challenging proximal aortic neck anatomy.

METHODS

Prospectively collected data from 147 consecutive patients who underwent EVR between December 1997 and April 2005 were supplemented with a retrospective review of medical records and radiological images. Unfavorable anatomic features were defined as neck diameter >28 mm, angulation >60 degrees, circumferential thrombus >50%, and length <10 mm. Eighty-seven patients with 0 adverse features (good necks) were compared with 60 patients with one or more adverse features (hostile necks).

RESULTS

Comparing the good neck with the hostile neck group, there were no significant differences in the incidence of primary technical success (p = 0.15), intraoperative adjunctive procedures (p = 0.22), early proximal type I endoleak (<30 days) (p = 1.0), late proximal type I endoleak (>30 days) (p = 0.57), distal type I endoleak (p = 0.40), type III endoleak (p = 0.51), secondary interventions (p = 1.0), aneurysm sac expansion (p = 0.44), or 30 day mortality (p = 0.70). The good neck group had a significantly increased incidence of type II endoleak (p = 0.023). By multivariate analysis, the incidence of intraoperative adjunctive procedures was significantly increased in the presence of severe angulation (p = 0.041, OR 3.08, 95% CI 1.05-9.04).

CONCLUSION

Patients with severely hostile proximal aortic neck anatomy may be treated with EVR, although severely angulated necks require additional intraoperative procedures. Early outcomes are encouraging and suggest that indications for EVR may be expanded to include patients with hostile neck anatomy.

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 (> or = 10% and > or = 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 > or = 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 (> or = 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 > or = 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.

Aneurysm Diameter and Proximal Aortic Neck Diameter Influence Clinical Outcome of Endovascular Abdominal Aortic Repair: A 4-Year EUROSTAR Experience

Our objective was to evaluate the effect of preoperative aneurysm and aortic neck diameter on clinical outcome after infrarenal abdominal endovascular aneurysm repair (EVAR). Data of patients in the European Collaborators Registry on Stent-Graft Techniques for Abdominal Aortic Aneurysm Repair (EUROSTAR) registry base who underwent EVAR with Talent stent grafts were analyzed. Patient characteristics and clinical outcomes were compared among four groups defined by preoperative abdominal aortic aneurysm (AAA) and proximal aortic neck diameter: A, AAA < or =60 mm and neck < or =26 mm; B, AAA >60 mm and neck < or =26 mm; C, AAA < or =60 mm and neck >26 mm; and D, AAA >60 mm and neck >26 mm. Over a 7-year period, 1,317 patients underwent EVAR. Patients in groups B and D were significantly older and had a higher American Society of Anesthesiologists score compared with groups A and C (p=0.002 and 0.003, respectively). Mortality rate was highest in group D (p=0.002), as were rupture and conversion rates (p=0.015 and 0.037, respectively). This study demonstrates that patients with an AAA >60 mm and a proximal aortic neck >26 mm have worse clinical outcome after EVAR.

Suprarenal Endograft Fixation Avoids Adverse Outcomes Associated with Aortic Neck Angulation

The advent of endovascular therapy has had a profound impact on repair of abdominal aortic aneurysms (AAA). Prudent patient selection, particularly in regard to unfavorable anatomy, is emerging as perhaps the most important determinant of endovascular abdominal aortic aneurysm repair (EVAR) outcome. The aim of this study was to examine the association of one such anatomic factor, proximal aortic neck angulation, with the incidence of adverse events following EVAR. Prospectively collected data on 289 EVAR repairs with the Talent endograft (Medtronic, Inc., Minneapolis, MN) from March 1998 to June 2000 were analyzed. Stent graft-specific adverse events studied were migration, endoleak, kinking, thrombosis, and AAA expansion. Computed tomography (CT) scanning with three-dimensional post-processing and/or aortography was used to measure aortic neck angle. Patients were categorized into one of four groups according to their neck angle: I (0-10 degrees); II (11-39 degrees); III (40-59 degrees); or IV (60-85 degrees). Outcomes were evaluated by chi-squared analysis and ANOVA. There was a direct correlation between AAA diameter and neck angle (p = 0.002). There was no difference in endoleak rate (p = 0.877), stent migration (p = 0.850), or AAA expansion rate (p = 0.599) between groups. Device kinking >45 degrees was associated with neck angulation > or = 60 degrees (p = 0.013), but not with other adverse outcomes. The average neck angle was 30 degrees in patients with endoleaks and 31 degrees in patients without endoleaks. Increasing aortic neck angulation was not associated with the selected adverse outcomes within 1 year following EVAR with the Talent stent graft using suprarenal fixation with the exception of graft kinking. This may be related to the graft design that permits suprarenal aortic fixatiou of the proximal stent graft, Whether severe degrees of angulation of 60 degrees or greater can be safely treated with suprarenal fixation requires further study.

Multicenter pivotal trial results of the Lifepath System for endovascular aortic aneurysm repair

PURPOSE

This study was undertaken to assess the results of endovascular aortic aneurysm repair with the Lifepath abdominal aortic aneurysm (AAA) graft system.

METHOD

In a prospective clinical trial, 23 centers used the Lifepath System balloon-expandable, modular bifurcated stent graft for elective endovascular aortic aneurysm repair. Stent grafts were sized according to computed tomographic angiography-based diameter measurements. All repairs were performed in the operating room through bilateral surgically exposed femoral arteries. Results were assessed with contrast agent-enhanced computed tomography scans and plain abdominal x-ray films at 1, 6, 12, 24, 36, and 48 months postoperatively.

RESULTS

Over 52 months (mean follow-up, 11 months), 227 patients (206 men, 21 women) were enrolled. Technical implant success rate was 98.7%. There were five (2.2%) conversions to open surgery: two emergently because of aortic perforation; to treat refractory endoleak, immediate in one and at 12 months in one; and to replace a device with wireform fractures that had migrated at 12 months, resulting in a proximal endoleak. The perioperative mortality rate was 1.3%. There was one operative death during a secondary procedure to repair perforation of the aorta. There were two perioperative deaths, from postoperative myocardial infarction (n = 1) and pulmonary embolus (n = 1). There were 12 late deaths, from coronary artery disease (n = 4), cancer (n = 2), respiratory failure (n = 2), sepsis (n = 1), or unknown cause (n = 3). Median length of stay was 2 days (mean, 4 days). There have been no AAA ruptures after successful implantation of the device, no graft limb thromboses, and no limb dislocations. At the time of operation endoleak was noted in 43 (19%) patients, but by 6 months this was reduced to 8 (5.9%) patients (type I, n = 1; type II, n = 7). There were no type III or type IV endoleaks. Secondary interventions to treat endoleaks included open conversion (n = 2), placement of extension cuffs (n = 4), repeated balloon dilation (n = 3), and coil embolization (n = 6). The two remaining secondary interventions were emergent treatment of postoperative bleeding from a groin incision, and a colon resection because of postoperative colonic ischemia, for a 12-month secondary intervention rate of 7.5%. Wireform fractures were noted in the first generation Lifepath device in 37 of 79 (47%) patients. Graft migration (>10 mm) was observed in five patients (2.2%), each of whom also had two or more fractures of the proximal anchoring wireforms. Migration resulted in a proximal attachment endoleak in one patient. In response to wireform fractures, the device was modified after the initial 79 patients were enrolled. Wireform fracture has been observed in six patients since this modification (4%), and in only one patient did this involve fracture of a proximal anchoring wireform; none of these patients has had endoleak or graft migration. By 12 months, mean aneurysm diameter was noted to decrease by 9 mm (P <.0001), and mean aneurysm volume by 42 mL (P <.0001) from the preoperative visit.

CONCLUSION

The Lifepath System demonstrates a low endoleak and secondary intervention rate and high sac regression rate, compared with other devices. The unique balloon-expandable design offers the advantages of precise placement and high radial force. The device appears to be highly resistant to limb thrombosis and modular component separation. Patients were protected from AAA rupture after successful device implantation, and demonstrated significant reduction in AAA diameter and volume. Fractures of the wireforms of the main body of the device have been observed. Careful long-term follow-up is necessary.

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 </=10 mm, (2) focal bulge in the neck >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.

Fabric tears as a new cause of type III endoleak with ancure endograft

PURPOSE

We present two case reports of type IIIb endoleak. One was due to fabric erosion caused by placement of a stent (Wallstent; W. L. Gore & Associates, Flagstaff, Ariz) after endovascular aneurysm repair; the other arose spontaneously. In both cases, an Ancure endograft (Guidant/EVT, Menlo Park, Calif) was placed.

CASE REPORTS

In case 1, a large endoleak developed 36 months after uncomplicated endovascular treatment of an abdominal aortic aneurysm. In case 2, endoleak developed 30 months after a complicated procedure. In both cases, two Wallstents were used to treat type I endoleak and limb kinking in the first postoperative months. One type III endoleak was within the endograft at the level of the stents.

CONCLUSION

To our knowledge, these are the first type III endoleaks reported in association with Ancure endografts. Placement of Wallstents inside endografts is of concern, and another indication for close monitoring during follow-up.

Aortoiliac morphologic correlations in aneurysms undergoing endovascular repair

PURPOSE

The feasibility of endovascular aneurysm repair depends on morphologic characteristics of the aortoiliac segment. Knowledge of such characteristics is relevant to safe deployment of a particular device in a single patient and to development of new devices for use in patients with a broader spectrum of anatomic variations.

METHODS

We evaluated findings on computed tomography scans for 277 patients being considered for endovascular aneurysm repair. Aortic neck length and angulation estimates were generated with three-dimensional trigonometry. Specific centerline points were recorded, corresponding to the aorta at the celiac axis, lowest renal artery, cranial aspect of the aneurysm sac, aortic terminus, right hypogastric artery origin, and left hypogastric origin. Aortic neck thrombus and calcium content were recorded, and neck conicity was calculated in degrees. Statistical analysis was performed with the Spearman rank correlation. Data are expressed as median and interquartile range.

RESULTS

Median diameter of the aneurysms was 52 mm (interquartile range, 48-59 mm) in minor axis and 56 mm (interquartile range, 51-64 mm) in major axis, and median length was 88 mm (interquartile range, 74-103 mm). Median proximal aortic neck diameter was 26 mm (interquartile range, 22-29 mm), and median neck length was 30 mm (interquartile range, 18-45 mm). The common iliac arteries were similar in diameter (right artery, 16 mm [interquartile range, 13-20 mm]; left artery, 15 mm [interquartile range, 11-18 mm]) and length (right, 59 mm [interquartile range, 50-69 mm]; left, 60 mm [interquartile range, 49-70 mm]). Median angulation of the infrarenal aortic neck was 40 degrees (interquartile range, 29-51 degrees), and median angulation of the suprarenal segment was 45 degrees (interquartile range, 36-57 degrees). By gender, sac diameter, proximal neck diameter, and iliac artery diameter were significantly larger in men. Significant linear associations were identified between sac diameter and sac length, neck angulation, and iliac artery diameter. As the length of the aneurysm sac increased the proximal aortic neck length decreased. Conversely, as the sac length decreased sac eccentricity increased. Mural thrombus content within the neck increased with increasing neck diameter.

CONCLUSIONS

There is considerable variability in aortoiliac morphologic parameters. Significant associations were found between various morphologic variables, links that are presumably related to a shared pathogenesis for aberration in aortoiliac diameter, length, and angulation. Ultimately this information can be used to develop new endovascular devices with broader applicability and improved long-term results.

Adjunctive procedures for the treatment of proximal type I endoleak: the role of peri-aortic ligatures and Palmaz stenting

PURPOSE

To investigate the feasibility, efficacy, and long-term effects of peri-aortic ligatures and Palmaz stenting used to treat proximal type I endoleak after endovascular repair (EVR) of abdominal aortic aneurysm (AAA).

METHODS

An 8-year single-center experience with proximal type I endoleak was reviewed; the records of the 55 identified cases were examined to ascertain the methods of treatment used. Among these, all 22 patients who were treated with peri-aortic ligatures and Palmaz stenting were segregated for analysis.

RESULTS

The 22 patients (14 men; mean age 74.6 years, range 66-85) with proximal type I endoleak (18 early, 4 late) selected for analysis underwent 23 secondary procedures: 15 involving peri-aortic ligatures and 8 Palmaz stent implantations. Of the 18 early endoleaks, 11 were treated intraoperatively and 7 were observed. Ten (45%) patients died within 30 days of endoleak treatment: 8 had early endoleaks. Five of the 10 deaths occurred in patients successfully treated with peri-aortic ligatures (3/10) or Palmaz stenting (2/7). The 12 (54%) surviving patients suffered no aneurysm-related deaths or secondary endoleaks over a median follow-up of 20 months (range 4-75).

CONCLUSIONS

Endoleak is an important mode of failure after endovascular repair. Peri-aortic ligatures and Palmaz stenting are feasible techniques for the treatment of proximal endoleak; however, the perioperative mortality of peri-aortic ligatures was higher when compared with other less invasive techniques. In contrast to other therapeutic options, these methods are more effective in the short and medium term.

The endovascular management of ruptured abdominal aortic aneurysms

Endovascular aneurysm repair (EVAR) is a controversial technique, which remains the subject of a number of prospective randomised trials. Although questions remain regarding its long-term durability objective evidence exists which demonstrates its reduced physiological impact compared with conventional open repair. If this technique could be used in patients with ruptured abdominal aortic aneurysm (AAA) it may reduce the high peri-operative mortality. A review of the literature identified a limited experience with EVAR of ruptured AAA. Only a small number of case series with selected patients exist. The majority of patients were haemodynamically stable. However, the selective use of aortic occlusion balloons allowed successful endovascular management in a small number of unstable cases. All investigators had access to an "off the shelf" endovascular stent-graft (EVG). Per-operative mortality ranged from 9 to 45% and may reflect increasing experience and patient selection. A number of patients who underwent successful EVAR were turned down for open repair. A number of important lessons have been learned from these studies but questions remain regarding patient suitability and staffing issues. If these difficulties can be surmounted then the technique may offer an alternative to open repair.

Type-II endoleaks following endovascular AAA repair: preoperative predictors and long-term effects

PURPOSE

To determine the significance of persistent type-II endoleaks and whether they can be predicted preoperatively in patients with abdominal aortic aneurysms (AAA).

METHODS

The charts of all AAA patients treated with the AneuRx stent-graft at a single center from 1996 to 1998 were reviewed. Patients with <12-month follow-up or type-I endoleaks were excluded. The presence or absence of type-II endoleaks was determined from duplex imaging and computed tomographic angiography. Three groups were identified and compared: 16 patients with persistent type-II endoleaks (PE), 14 patients with transient type-II endoleaks (TE), and 16 patients with no endoleak (NE).

RESULTS

The groups did not differ with regard to age, preoperative comorbidities, follow-up time, and AAA neck diameter and length. AAA diameters were 57.1 +/- 9.0 mm for NE, 63.4 +/- 11.4 mm for TE, and 55.6 +/- 4.2 mm for PE. The inferior mesenteric artery (IMA) was patent in 5 (31%) NE patients, 6 (43%) TE patients, and 13 (81%) PE patients (p < 0.01). The number of patent lumbar arteries visualized preoperatively was 0.5 +/- 1.0 in NE, 1.3 +/- 0.8 in TE, and 2.4 +/- 0.6 in PE (p < 0.0001). Patent IMAs (RR 0.82, p < 0.01) and >2 lumbar arteries (RR 0.40, p < 0.0001) were identified as independent preoperative risk factors for persistent endoleaks. There were no changes in mean diameter or volume in aneurysms with persistent endoleaks.

CONCLUSIONS

No adverse clinical events were related to the presence of type-II endoleaks, but there was no decrease in aneurysm size in patients with persistent type-II leaks. Patients with a large, patent IMA, or >2 lumbar arteries on preoperative CT angiography are at higher risk for persistent type-II endoleaks.