Failure of endovascular abdominal aortic aneurysm graft limbs

Side-by-side deployment of gore excluder legs at a narrow terminal aorta for endovascular aneurysm repair

PURPOSE

A narrow terminal aorta is a risk factor for endograft occlusion after endovascular aneurysm repair. To minimize limb complications, we used Gore Excluder legs positioned side-by-side at the terminal aorta. We investigated the outcomes of our strategy for endovascular aneurysm repair in patients with a narrow terminal aorta.

METHODS

We enrolled 61 patients who underwent endovascular aneurysm repair with a narrow terminal aorta (defined as < 18 mm in diameter) from April 2013 to October 2021. The standard procedure involves complete treatment with the Gore Excluder device. When other types of main body endografts were used, they were deployed proximal to the terminal aorta, and we used the Gore Excluder leg device in the bilateral limbs. Postoperatively, the intraluminal diameter of the legs at the terminal aorta was measured to assess the configuration.

RESULTS

During the follow-up period (mean: 2.7 ± 2.0 years), there were no aorta-related deaths, endograft occlusions, or leg-related re-interventions. There were no significant differences between the pre- and postoperative ankle-brachial pressure index values in the dominant and non-dominant legs (p = 0.44 and p = 0.17, respectively). Postoperatively, the mean difference rate (defined as [dominant leg diameter-non-dominant leg diameter]/terminal aorta diameter) was 7.5 ± 7.1%. The difference rate was not significantly correlated with the terminal aortic diameter, calcification thickness, or circumferential calcification (r = 0.16, p = 0.22; r = 0.07, p = 0.59; and r = - 0.07, p = 0.61, respectively).

CONCLUSIONS

Side-by-side deployment of Gore Excluder legs produces acceptable outcomes for endovascular aneurysm repair with a narrow terminal aorta. The endograft expansion at the terminal aorta is tolerable without influencing calcification distribution.

Escalation of Antithrombotic Therapy Should Be Considered in the Presence of Intraluminal Prosthetic Graft Thrombus Following Endovascular Aneurysm Repair

Objectives

Intraluminal prosthetic graft thrombus (IPT) following Endovascular Aneurysm Repair (EVAR) can have serious consequences. The aim of this study was to assess the prevalence of IPT and to identify the risk factors for its formation and progression.

Methods

This was a retrospective study of 258 patients who had EVAR between 2015 and 2018. Demographic data, comorbidities, operative data, antithrombotic therapy, CT anatomical data, IPT characteristics (site, regression, and progression), and re-interventions were collected. Univariable analysis followed by multivariable logistic regression and Cox regression were used for data analysis.

Results

The mean age of patients was 76 years (range 55-95) and 27 (10.5 %) were females. IPT was present in 26 patients (10.1%) with a median time to occurrence of six (range 1- - 24) months. Of the group that developed IPT, six (23.1 %) developed symptoms and two (7.7%) had re-interventions. Multivariable logistic regression analysis revealed peripheral arterial disease to be associated with the formation of IPT (OR 7.4, 95% CI 1.6-35.3, p = 0.02) and escalation of antithrombotic therapy was associated with regression or prevention of progression of IPT (OR 0.1, 95% CI 0.0-0.6, p = 0.01).

Conclusion

PAD is associated with the formation of IPT after EVAR and warrants consideration of escalation of antithrombotic therapy to prevent further progression and complications.

Incidence and predictive factors for endograft limb patency of the Fenestrated Anaconda™ endograft used for complex endovascular aneurysm repair

OBJECTIVE

To describe the incidence, risk factors and outcomes of treatment for limb occlusion in patients treated for complex (thoraco-)abdominal aortic aneurysms (AAA) with the Fenestrated Anaconda™.

METHODS

Between June 2010 and May 2018, 335 patients underwent elective fenestrated aortic aneurysm repair in 11 participating centers using the Fenestrated Anaconda™ with a median follow-up of 14.3 months (IQR 27.4). The primary outcome measure was freedom-from-limb-occlusion. Secondary outcome measures were freedom-from-limb-related-reintervention, secondary patency, and risk factors associated with limb occlusion.

RESULTS

Thirty (9.0%) patients presented with limb occlusion during follow-up with freedom-from-limb-occlusion of 98.5%, 91.2%, and 81.7% at 30-days, 1 and 5 years, respectively. In 87% of cases, no obvious cause for limb occlusion was documented. Primary occlusion occurred within 30-days in 36.7% and within 1 year in 80.0%. Twenty-three (6.9%) patients underwent an occlusion-related reintervention; seven (23.3%) patients were treated conservatively. Freedom-from-limb-occlusion-related-reintervention at 30-days, one and five years was 97.8%, 93.2% and 88.6%, respectively. Secondary patency was 91.3% after 1-month and 86.2% after 1 and 5 years, respectively. Female sex (OR 3.27 - 95% CI 1.28 to 8.34, P = .01) was a statistically significant predictor for limb occlusion. A higher percentage of thrombus in the aneurysm sac appeared to be protective for limb occlusion (0% compared to <25%: OR 0.22 - 95% CI 0.07 to 0.63, P = .01; 0% compared to 25-50%: OR 0.20 - 95% CI 0.07 to 0.57, P = .00 and 0% compared to >50%: OR 0.08 - 95% CI 0.02 to 0.38, P = .00), as did iliac angulation (OR 0.99 - 95% CI 0.98 to 1.00, P = .04).

CONCLUSION

Limb occlusion remains a significant impediment of endograft durability in patients treated with the Fenestrated Anaconda™, especially in female patients. Controversially, a high aneurysmal thrombus load and a high degree of iliac angulation appeared to be protective for limb occlusion, for which no obvious cause could be identified.

Limb Occlusion Rate after EVAR With Individualized Graft Limb Selection and a Liberal Protocol of Primary Relining

BACKGROUND

This study analyses limb occlusion rates after endovascular aneurysm repair (EVAR) with a strategy including stent-graft limb selection and liberal primary stenting (relining) in anatomies at higher risk for occlusion with uncovered self-expandable or balloon-expandable stents.

METHODS

All patients undergoing elective EVAR with a bifurcated stent-graft between January 2010-August 2018 were included. A protocol involving personalized stent-graft selection and liberal primary relining based on preoperative imaging was followed during the whole period. Primary endpoints were technical success and primary limb patency during follow-up. Secondary endpoints included mortality and limb reintervention rates. Risk factors associated to limb patency and reintervention rates were analyzed.

RESULTS

Six hundred and fifteen patients (548 males; mean age 72.9 ± 9 years) were included. Overall technical success was 98.5% (606/615). One (0.16%) patient died during the first 30 days. Of the 1230 limbs, 96 (8%) were deemed at risk for occlusion in view of the anatomy, and primarily relined in 62 patients. Estimated primary limb patency at 6 months, 1 year and 3 years was 99.5 ± 0.2%, 99.2 ± 0.3% and 98.5 ± 0.5%, respectively. Freedom from limb-related reintervention at 6 months, 1 year and 3 years was 98.1 ± 0.4%, 97.4 ± 0.5% and 95.6 ± 0.7%, respectively. Only one (1%) of the 96 relined limbs occluded during follow-up. No differences were found in terms of patency or freedom from reintervention between limbs at risk that were primary stented and limbs without adjunctive stents. Gore Excluder stent-grafts presented better patency (Breslow P = 0.005) and lower reintervention rates (Breslow P = 0.001) than other devices during follow-up. Peripheral artery disease was also a risk factor for reintervention (Breslow P = 0.015).

CONCLUSION

Liberal use of primary limb relining in patients with iliac anatomy at higher risk for occlusion appears to be a safe and effective strategy to preserve limb patency after EVAR. Gore Excluder graft limbs present better patency and lower reintervention rates than other stent-graft types.

Endovascular Aneurysm Repair with Bifurcated Stent Grafts in Patients with Narrow Versus Regular Aortic Bifurcation: Systematic Review and Meta-analysis of Comparative Studies

BACKGROUND

Narrow aortic bifurcation (NAB) is considered as a risk factor for endograft limb thrombosis. The purpose of the study was to investigate the effect of narrow aortic bifurcation on outcomes of elective endovascular aneurysm repair (EVAR).

METHODS

A systematic review that conformed to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was performed. We searched electronic bibliographic databases using a combination of controlled vocabulary (thesaurus) and free-text terms to identify relevant studies comparing outcomes of EVAR in patients with NAB versus those with regular aortic bifurcation. Pooled estimates of dichotomous outcomes were calculated using odds ratio (OR) and those of continuous outcomes using mean difference and 95% confidence interval (CI). To account for expected heterogeneity, the random-effects model was applied for statistical analysis.

RESULTS

Six observational studies were included, reporting a total of 2,673 patients (412 with NAR and 2,261 with friendly anatomy). Perioperative mortality was similar between the groups (OR 1.14, 95% CI 0.30-4.34, P = 0.85, I² = 0%). Limb stenosis and kinking requiring additional intraoperative procedures was significantly more common among patients with NAB (OR 3.02, 95% CI 2.16-4.22, P < 0.00001, I² = 0%). Nevertheless, 30-day reintervention rate was similar between the groups, as was the rate of limb occlusion during follow-up.

CONCLUSIONS

Available evidence suggests that at the expense of significantly more intraoperative additional procedures, EVAR with bifurcated devices can be safely performed in patients with NAB.

Decreased Ischemic Complications After Endovascular Aortic Aneurysm Repair With Newer Devices

Ischemic complications after endovascular abdominal aortic aneurysm repair (EVAR) are well-recognized and have been reported to be as high as 9%. The goal of our study was to examine the incidence, management, and outcome of ischemic complications at our institution after EVAR and to compare complications according to graft type and time period. This is a retrospective review of all EVARs performed at our institution from 1993 through 2005 (n = 430). EVAR was performed in asymptomatic patients in most cases. Follow-up consisted of a computed tomography scan and office visit at 1, 6, and 12 months and yearly thereafter. Ischemic complications after EVAR have decreased significantly with the advent of lower-profile devices with easier delivery systems and supported limbs. Simultaneous coil embolization of internal iliac artery at the time of EVAR implant does not appear to increase the risk of pelvic or lower-extremity ischemia, can be done safely, and does not need to be staged.

Clinical and anatomical variables associated in the literature to limb graft occlusion after endovascular aneurysm repair compared to the experience of a tertiary referral center

INTRODUCTION

Limb graft occlusion (LGO) is the third reason for hospital readmission after endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm. We reviewed the clinical features, incidence, anatomical and devices related predictive factors for LGO after EVAR, and compared them with our experience.

EVIDENCE ACQUISITION

EVAR between 2010-2017 were included. Patients with LGO (LGO group) were matched for age and type of endograft with the rest of the entire cohort without LGO (control group). Clinical, anatomical, operative, outcome, and follow-up data were collected.

EVIDENCE SYNTHESIS

Two hundred seventy-six EVAR, (30 aorto-uniliac), 276 patients. The incidence of LGO was 2.5% (seven limbs, seven patients) at 27±24.6 days. Symptomatic patients were successfully treated. No mortality, limb loss, critical limb ischemia or residual claudication due to LGO was observed. Fifty patients resulted from the matching. Among the predictive factors of LGO between the two groups, significant differences were observed in graft limb oversizing ≥15% (57.1% vs. 8%, P=0.005), or kinking (42.9% vs. 2%, P=0.01), and diameter of the aortic bifurcation <20 mm (71.4% vs. 20%, P=0.01). Logistic regression analysis showed that these three variables increased the risk of LGO (P=0.003, P=0.006, and P=0.01, respectively).

CONCLUSIONS

The strongest predictive factors of LGO issued from our review were: extension in the external iliac artery, or small diameter; tortuous, angled, and calcific iliac axis; excessive oversizing of the limb graft, or kinking; use of old generation devices; EVAR performed outside the instructions for use. Limb graft oversizing >15%, or kinking, and aortic bifurcation <20 mm appear to be independent predictive factors of LGO.

Long-Term Outcomes of Percutaneous Stenting of Aortic Endograft Limb Occlusion

INTRODUCTION

To investigate the safety and efficacy of percutaneous stenting for the management of chronic ischemia caused by endograft limb occlusion following endovascular aortic aneurysm repair (EVAR).

METHODS

This is a retrospective, single-center study investigating all patients who underwent percutaneous endovascular covered or bare metal stent placement for the management of intermittent claudication (IC) or critical limb ischemia following EVAR limb occlusion, between January 2010 and October 2017. Cases suffering from acute limb ischemia were treated surgically and were excluded from the analysis. Primary outcome measures were technical success and symptoms-free interval. Secondary outcome measures included clinically driven target-lesion reintervention (TLR)-free survival, primary patency, and complication rates.

RESULTS

Of 29 limb occlusions, 11 limbs (11 patients; 100% male; mean age: 71.6 ± 6.9 years) were treated percutaneously and were included in the study. The majority suffered from IC (10/11; 90.9%) with a single case of rest pain. Technical success was obtained in 10 patients (90%). No major complications occurred. Mean follow-up time was 37.6 ± 25.7 months. Stent grafts were mainly used, while and in 2 cases (18.18%), only nitinol bare stents were deployed. According to Kaplan-Meier analysis, both symptoms-free interval and primary patency were 83.33% in up to 5 years follow-up. TLR-free survival was 100% at 5 years, as 2 cases of claudication relapse were managed conservatively.

CONCLUSIONS

Percutaneous stenting for the management chronic ischemia due to EVAR limb occlusion is feasible and safe, with satisfactory long-term outcomes. Careful patient selection warrants clinical success.

Bowel ischaemia after endovascular aneurysm repair

The aim of this review was to investigate presentation, aetiology, management, and outcomes of bowel ischaemia following EVAR. We present a case report and searched electronic bibliographic databases to identify published reports of bowel ischaemia following elective infra-renal EVAR not involving hypogastric artery coverage or iliac branch devices. We conducted our review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement standards. In total, five cohort studies and three case reports were included. These studies detailed some 6,184 infra-renal elective EVARs, without procedure-related occlusion of the hypogastric arteries, performed between 1996 and 2014. Bowel ischaemia in this setting is uncommon with an incidence ranging from 0.5 to 2.8 % and includes a spectrum of severity from mucosal to transmural ischaemia. Due to varying reporting standards, an overall proportion of patients requiring bowel resection could not be ascertained. In the larger series, mortality ranged from 35 to 80 %. Atheroembolization, hypotension, and inferior mesenteric artery occlusion were reported as potential causative factors. Elderly patients and those undergoing prolonged procedures appear at higher risk. Bowel ischaemia is a rare but potentially devastating complication following elective infra-renal EVAR and can occur in the setting of patent mesenteric vessels and hypogastric arteries. Mortality ranges from 35 to 80 %. Further research is required to identify risk factors and establish prophylactic measures in patients that have an increased risk of developing bowel ischaemia after standard infra-renal EVAR.

Self expandable stent application to prevent limb occlusion in external iliac artery during endovascular aneurysm repair

Purpose

Iliac extension of stent-graft during endovascular aneurysm repair (EVAR) increases the incidence of limb occlusion (LO). Hypothetically, adjunctive iliac stent (AIS) could offer some additional protection to overcome this anatomic hostility. But still there is no consensus in terms of effective stent characteristics or configuration. We retrospectively reviewed our center's experience to offer a possible answer to this question.

Methods

Our study included 30 patients (38 limbs) with AIS placed in the external iliac artery (EIA) from January 2010 to December 2013. We classified iliac tortuosity based on anatomic characteristics. AIS's were deployed in EIA with a minimum 5-mm stick-out configuration from the distal edge of the stent-graft.

Results

According to the iliac artery tortuosity index, grade 0, grade 1, and grade 2 were 5 (13.2%), 30 (78.9%), and 3 (7.9%), respectively. The diameter of all AIS was 12 mm, which was as large as or larger than the diameter of the stent-graft distal limb. SMART stents were preferred in 34 limbs (89.5%) and stents with 60-mm length were usually used (89.5%). During a mean follow-up of 9.13 ± 10.78 months, ischemic limb pain, which could be the sign of LO, was not noticed in any patients. There was no fracture, kinking, migration, in-stent restenosis, or occlusion of AIS.

Conclusion

The installation of AIS after extension of stent-graft to EIA reduced the risk of LO without any complications. AIS should be considered as a preventive procedure of LO if stent-graft needs to be extended to EIA during EVAR.

One Year Outcome Using Newer Generation Endografts: A National Multicenter Study on Real Word Practice

BACKGROUND

The aim of this study was to assess the 1 year outcomes following endovascular aortic aneurysm repair (EVAR) with the use of newer generation endografts.

METHODS

Retrospective analysis was conducted of prospectively collected multicenter data from 385 EVARs. Newer endografts were defined as those introduced after 2004. Patients' demographics and comorbidities, type of operation, and abdominal aortic aneurysm (AAA) morphological characteristics were analyzed. Computer tomography was performed 1 month and 1 year post-EVAR.

RESULTS

Mean age of the patients was 71.3 years; in 335 cases the intervention was elective. The mean AAA sac, neck diameter, and length were 57.15, 24.5, and 28.97 mm, respectively. Ninety-four endoleaks were recorded in 92 patients (25%), including 11 type 1a (T1aE), 3 type 1b, and 78 type 2 (T2E) endoleaks. On logistic regression analysis, neck diameter >30 mm (P = 0.032) and initial AAA sac diameter >55 mm (P = 0.031) were associated with T1aE. No association was found with T2E. Overall, 107 (27%) patients had sac expansion at 1 year associated with the presence of T2E (P = 0.019). No association was observed between T1aE or T2E and specific endograft.

CONCLUSIONS

Newer generation endografts show very satisfactory performance even in difficult anatomies. T1aE was associated with initial sac and neck diameter, while AAA sac expansion was associated with the presence of T2E.

Lack of Iliac Engagement Correlates With Iliac Limb Complications Following Standard EVAR

Objective:

An adequate distal sealing zone is a prerequisite for successful endovascular aneurysm repair (EVAR). Poor engagement of iliac limbs within the common iliac artery potentially increases the risk of limb-related complications. The aim of this study was to investigate the proportion of common iliac artery used for distal sealing as a predictor of iliac limb complications following standard EVAR.

Methods:

This was a retrospective case controlled study where an iliac complication group was compared to a larger control group from the unit database. Core analysis of postoperative computed tomography scans was used to ascertain the percentage engagement of the iliac limb of the stent graft within the native iliac artery in both groups.

Results:

There were 240 limbs in the control group and 33 limbs in the complications group. Complications included 10 endoleaks, 1 iliac limb dislocation, 2 insufficient engagement, 4 occlusions, and 16 kinks. The proportion of common iliac artery engagement was significantly higher in the control group compared with the complications group (75.3:68.6%, P = .003).

Conclusions:

Increased engagement in the common iliac artery following standard EVAR reduces the risks of limb complications. A clinical guide utilization of more than 70% of the total length of common iliac artery could be used as this was associated with a significantly lower rate of iliac limb complications following standard EVAR.

A modified technique for Gore Excluder limb deployment in difficult iliac anatomy during endovascular abdominal aortic aneurysm repair

Complex iliac anatomy including extreme tortuosity constitutes a relative contraindication for endovascular abdominal aortic aneurysm repair with additional risk of limb-graft occlusion. The Gore Excluder limb-graft is a flexible stent-graft, which adapts easily to iliac tortuosity. Nevertheless, the presence of the stiff guide wire does not always allow for an ideal apposition of the stent graft to the angulated common iliac artery vessel wall. We describe herein a modified technique for Gore Excluder limb-graft deployment with partial removal of the stiff wire in cases with difficult tortuous or narrow iliac arteries during endovascular abdominal aortic aneurysm repair.

Tratamento endovascular da oclusão de ramo ilíaco de endoprótese bifurcada de aorta abdominal: trombectomia rotativa e aspirativa seguida de angioplastia com stent primário

A oclusão de ramo ilíaco de endoprótese bifurcada de aorta surge como complicação decorrente da correção endovascular do aneurisma de aorta abdominal e várias abordagens terapêuticas têm sido empregadas para o tratamento dessa complicação em casos de isquemia de membro inferior. Apresentamos dois casos de tratamento totalmente percutâneo da oclusão de ramo ilíaco de endoprótese de aorta abdominal com dispositivo de trombectomia rotativa e aspirativa seguida de angioplastia com stent primário, sem complicações operatórias.

Treatment of complications following endovascular repair of abdominal aortic aneurysms

Endovascular aneurysm repair (EVAR) is an important treatment option for abdominal aortic aneurysms, with lower perioperative morbidity and mortality rates than open surgical aneurysm repair. However, EVAR is associated with several unique complications that are not encountered with surgical repair such as endoleaks, graft migration, and renal artery occlusion. Preservation of the morbidity and mortality advantages of EVAR relies on the successful treatment of these complications by minimally invasive, endovascular approaches. Some of the techniques used to treat EVAR complications include balloon dilation and stenting, deployment of additional stent-graft pieces, coil embolization, and thrombolysis. Although the employment of these endovascular salvage techniques is common, data regarding their intermediate- to long-term efficacy is sparse, and further studies are needed to determine their efficacy in preventing conversion to open aneurysm repair and aneurysm rupture.

Hybrid Endograft Solution for Complex Iliac Anatomy: Zenith Body and Excluder Limbs

The purpose of this study was to evaluate single-center results with selective use of Gore Excluder limbs (W.L. Gore & Associates, Flagstaff, AZ) in a Cook Zenith body (Cook Inc, Bloomington, IN) for elective endovascular abdominal aortic aneurysm (AAA) repair. A prospectively held database for patients with AAA, who were treated endovascularly between March 1999 and July 2008, was queried for patients treated with a Cook Zenith body and one or two Gore Excluder limbs. Indication, technical success, late limb occlusion, and disconnection were evaluated. From 276 patients who were treated with a Zenith body, 29 underwent repair with hybrid graft components with, in total, 41 Gore Excluder limbs. The indication was always complex iliac anatomy. The primary technical success rate in this group was 89% (26 of 29 patients), with a primary assisted technical success rate of 100%. Mortality at 30 days was 0%. The mean follow-up was 19.4 months (range 2–64 months). Late mortality was 13.8% (4 of 29), with no aneurysm-related death. No graft limb occlusion or disconnection occurred during follow-up. No reintervention was needed in the hybrid endograft group. The use of a Cook Zenith body with Gore Excluder limb(s) in case of adverse iliac anatomy is feasible and showed no adverse effects at the midterm follow-up.

Reduced access aortic exposure (RAAE) technique for infrarenal abdominal aortic aneurysm (AAA) repair

OBJECTIVE

A reduced access aortic exposure (RAAE) technique for repair of infrarenal AAA repair has been evaluated and the short-term surgical outcomes are compared with conventional open repair (OPEN).

METHODS

All consecutive patients having repair of infrarenal AAA over a period of 3 years were included in this study. A group of these patients had AAA repair using the RAAE technique with a small midline incision (<8 cm). Patient characteristics and peri-operative outcomes were compared with the other group treated with the traditional full-length midline incision (OPEN).

RESULTS

Sixty patients underwent AAA repair in this study (38 in the RAAE group and 22 in the OPEN group). The age, sex distribution and co-morbidities were similar across the two groups (median age 76 and 75 years respectively). The RAAE group had a significantly shorter Intensive care stay (2 vs. 4 days, p=0.041) and a shorter total hospital stay (9 vs. 14 days, p=0.004). Significant postoperative chest infection was recorded in 13% (5/38) in the RAAE group as compared to 41% (9/21) in the OPEN group (p=0.025).

CONCLUSIONS

The RAAE technique for infra renal AAA repair is feasible and safe, and allows quicker postoperative recovery with comparable morbidity and mortality to the conventional technique.

Long-term Results of Femoro-Femoral Crossover Bypass After Endovascular Aortouniiliac Repair of Abdominal Aortic and Aortoiliac Aneurysms

Aortouniiliac stent grafts allow the endovascular treatment of complex anatomy aortoiliac aneurysms. The main drawback is the need for femoro-femoral crossover bypass, with its complications and its patency limitations. However, some authors have shown good results of femoro-femoral crossover bypass in aneurysmal disease. In this article, initial and long-term results of our experience in femoro-femoral crossover bypass revascularization after endovascular aortouniiliac stent grafts repair of aortoiliac aneurysms is reported. Prospective collection, intention-to-treat, and retrospective analysis maintained database. Femoro-femoral crossover bypass patency assessment of all patients treated between January 1999 and September 2002, compared patients with or without associated occlusive arterial disease. Urgent indications were excluded. In total of 52 patients, with a mean age 72.6 years, 30.8% of patients were identified with associated occlusive arterial disease. Initial systemic and local, access site, complications were 7.7% and 7.7%, respectively, no early thrombosis or death is reported. Primary patency was 90.9% at 54 months, 66 months assisted primary and secondary patency were 97.7% and 100%, respectively. The 48-month survival rate was 84.2%. No significant differences between patients with or without associated occlusive arterial disease were found. Femoro-femoral crossover bypass after aortouniiliac stent grafts treatment of aortoiliac aneurysms shows excellent initial and long-term patency and low complication rate.

Development of endovascular stent-grafts

The very first experiences in the early 1990s with endovascular aortic stent-grafts were associated with significant numbers of complications including an inability to deploy the stent-graft, conversion to open surgery, and aneurysm rupture. By the mid-1990s, improved home-made and commercially available stent-grafts started to appear. These devices could be successfully deployed in the aorta, achieving aneurysm exclusion with low morbidity and mortality. However, follow-up results raised concerns about the longer-term durability. Gradually, too, these problems have been addressed such that, in the recent UK multi-centre randomized controlled trial of endovascular versus open aneurysm repair, aneurysm-related mortality was 3 per cent less in the endovascular group four years following surgery. Currently the indications for aortic stent-grafts are being expanded. It is now possible to maintain perfusion successfully in aortic side branches and to treat aneurysms that would have once been thought untreatable. This review paper reviews the main developments in endovascular stent-grafting and the major role played by medical engineering and technology.

Limb Graft Occlusion Following EVAR: Clinical Pattern, Outcomes and Predictive Factors of Occurrence

INTRODUCTION

We reviewed our experience with limb occlusion after EVAR in order (1) to assess the clinical pattern and treatment options (2) to assess outcomes and (3) to identify predictive factors of occurrence.

MATERIALS AND METHOD

Between 1995 and 2005, 460 AAA patients were electively treated with a variety of commercially available stent grafts. There were 369 bifurcated and 91 aortouniiliac grafts (829 limbs). Follow-up included physical examination, plain X-ray, Duplex ultrasonography, and spiral computed tomographic scans at 1, 6, 12 months and annually thereafter. All pertinent data were collected prospectively and analysed retrospectively. The follow-up period ranged from Day 0 to 104 months, with a median follow-up of 23.4 months.

RESULTS

36 limbs in 33 patients (7.2%) occluded between Day 0 and 71 months (average: 9.5 months) after EVAR. Presentation was acute ischemia in 11 cases, rest pain in 9, claudication in ten. Four occlusions remained asymptomatic and two occurred intraoperatively. Treatment was femoro-femoral cross-over graft in 19 cases, axillo-femoral bypass in three, thrombectomy and stent in three, thrombolysis and stent in nine, and conservative in two. One patient (3%) died of multiple organ failure after thrombolysis. There was no amputation. Reocclusions occurred in two patients (6.1%). Multivariate logistic regression showed that kinking (odds ratio [OR] 11.9; confidence interval [CI] 3.39-42.1; p=0.0001), first graft generation (OR 2.87; CI 1.25-6.62; p=0.017) and younger age (OR 1.05; CI 1.00-1.09; p=0.034) were independently related to the occurrence of graft limb occlusion.

CONCLUSION

Acute graft limb occlusion is not rare after EVAR. The frequency of limb occlusion has declined with current stent grafts generation. Although surgery and endovascular treatments are efficient and safe, development of a graft limb kink should lead to aggressive pre-emptive treatment to prevent occlusion.

Challenges associated with the integration of endovascular repair of abdominal aortic aneurysms in a community hospital

PURPOSE

There has been considerable debate regarding the proper place for endovascular repair (ER) of abdominal aortic aneurysms (AAAs) versus traditional open repair (OR). Our study compared preoperative patient demographics and outcomes for elective, asymptomatic AAA repairs performed at our center over a 33-month period.

METHODS

For this study, we selected 342 consecutive elective infrarenal AAA repairs performed between July 1, 2000, and March 31, 2003, at Riverside Methodist Hospital. The patients underwent either ER or OR, depending on patient and surgeon collaborative determinations. Ruptured and symptomatic AAAs were excluded from our study. Preoperative demographics, anesthesia, complications, and discharge status for the 2 groups were analyzed, and statistical analysis was done to determine statistically significant differences.

RESULTS

The preoperative status of the ER and OR patient groups were essentially similar. There were only 3 significant differences between the 2 groups: alcohol use was higher for the OR group than for the ER group (12.0% versus 5.2%; P = .04), and the incidence of type II diabetes mellitus and peripheral vascular disease were lower for the OR group compared with the ER group (6.7% versus 13.4% [P = .04] and 18.3% versus 30.6% [P = .008], respectively). The OR group used more general anesthesia than the ER group (99% versus 86%; P < .001) and had more complications, including dysrhythmia (8.65% versus 1.59%; P = .005), ileus (13.94% versus 0.79%; P < .0001), infection (8.17% versus 0.0%; P = .0007), respiratory complications (12.50% versus 1.59%; P = .0003), and renal complications (5.29% versus 0.79%; P = .032). The ER group had a higher rate of wound hematoma (4.76% versus 0.48%; P = .007). ER patients also had significantly less blood loss (379 mL versus 1930 mL; P < .001), a better independent discharge status (P < .0001), a shorter length of stay (1.8 days versus 8.2 days; P < .001), and a lower mortality rate (0.75% versus 3.85%; P = .0954).

CONCLUSIONS

From our study we cautiously continue to encourage the consideration of the ER of AAAs in our patient population while being mindful of its limitations.

Complications of Endovascular Repair of Abdominal Aortic Aneurysms: A Review

The endovascular procedure for repair of abdominal aortic aneurysms has had an enormous impact on the treatment of this challenging disease. Complications, however, do occur and it is important to have a thorough understanding of the array of complications and appropriate management strategies. In this review of endovascular complications, we describe early and late complications paying particular attention to preventive, treatment and surveillance strategies.

Adjunctive primary stenting of Zenith endograft limbs during endovascular abdominal aortic aneurysm repair: Implications for limb patency

OBJECTIVE

Endograft limb occlusion is an infrequent but serious complication of endovascular abdominal aortic aneurysm (AAA) repair. The insertion of additional stents within the endograft limb may prevent future occlusion. This study evaluates limb patency with and without adjunctive stenting of endograft limbs at the time of endovascular AAA repair.

METHODS

We performed a retrospective review of 248 patients who underwent endovascular abdominal aortic aneurysm repair with the Zenith AAA endovascular graft between 1999 and 2004. Among these patients, two groups were identified: 64 patients with adjunctive stents placed in 85 limbs and 184 patients without additional bare stent placement in endograft limbs at the time of endovascular AAA repair.

RESULTS

Women comprised 23% of stented and 11% of unstented patients (P = .02). The mean length of follow-up in the stented and unstented groups was 2.0 years. There were 13 instances of limb thrombosis in 13 patients (5.2% of patients, 2.7% of limbs), all in the unstented group. No limb occlusions occurred in the presence of adjunctive bare metal stents. Seventy-three percent of the occlusions occurred < or = 6 months of endovascular AAA repair. Two patients (15%) had no symptoms of lower-extremity ischemia despite graft limb occlusion and did not undergo intervention. The others underwent thrombectomy (n = 2), thrombectomy with bare stent placement (n = 3), femoral-femoral bypass (n = 4), thrombolysis (n = 1), and thrombolysis with bare stent placement (n = 1). Of the seven who underwent thrombectomy or thrombolysis, three had no additional stents placed at the secondary procedure, and two of these three went on to rethrombose. By life-table analysis, primary patency at 3 years in the stented and nonstented limbs was 100% +/- 0% and 94% +/- 3%, respectively (P = .05).

CONCLUSIONS

The intraoperative insertion of additional bare metal stents appeared to eliminate the risk of thrombosis and was without complication. Of the 85 stented limbs in this series, not one occluded. The overall rate of limb thrombosis was low, with most limb occlusions occurring < or = 6 months of stent-graft insertion, and would probably have been even lower had we been able to identify all high-risk cases for prophylactic adjunctive stenting. Limb occlusion denotes an underlying problem with the graft, which if left untreated after thrombectomy or thrombolysis will lead to rethrombosis. Postoperative imaging was of little value in detecting impending limb occlusion. Based on these findings, we believe one should identify and stent any limbs that appear to be at risk for thrombosis, but this study lacks the data to predict which limbs need stenting.

Are type II endoleaks after endovascular aneurysm repair endograft dependent?

PURPOSE

Most clinical end points after endovascular aneurysm repair (EVAR) are endograft-specific, but type II endoleaks have been assumed to be an unavoidable consequence of the repair method and independent of the type of endograft used. Some recent data have suggested that the rate of type II endoleaks may also be graft-dependent. We reviewed a large clinical experience with six endografts to determine the behavior of type II endoleaks and whether they are graft-specific.

METHODS

All elective EVAR cases from five university institutions from 1996 to 2003 were retrospectively analyzed. Endografts used in <50 patients were excluded. Endoleaks were diagnosed and classified from contrast-enhanced computed tomography (CT) scans by the treating surgeons. Results of angiography and interventions for endoleaks were tracked. The rate of type II endoleaks was compared among endografts at 1, 6, and 12 months, and yearly thereafter. Statistical significance was defined as P < .05.

RESULTS

During the study period, 1909 patients underwent elective EVAR and had an adequate imaging follow-up at one of the specified time points. At 1 month, the overall rate of type II endoleak was 14.0% (range, 9.8% to 25.2%.) The Excluder had a significantly higher incidence of type II endoleaks at 1 month but was similar to most other grafts during longer follow-up. At 6 months, the overall rate of type II endoleak was 16.3% (range, 8.3% to 16.8%). The Talent and Lifepath had an apparent lower initial rate of type II leaks, but this was only significant for the Talent at 6 months compared with Excluder, Zenith, and Ancure, and at 1 year compared with Excluder and Zenith. No graft had a long-term statistically significant difference in the rate of type II endoleak formation. Intervention rates varied by institution and graft type but in general were quite low. Of 25 successful interventions (Ancure, 12; AneuRx, 8; Excluder, 2; Lifepath, 2; Zenith, 1; Talent, 0), 21 were performed during the first year. Interim spontaneous resolution, defined as a negative CT scan after a CT positive for endoleak, was high, especially in the first year. Resolution of type II endoleaks occurred in 54 (33%) of 164 between 1 and 6 months, in 37 (33%) of 112 between 6 and 12 months, in 20 (35%) of 57 from 12 to 24 months, and in 5 (20%) of 25 between 24 and 36 months. The various grafts had a nearly identical pattern, but the rates were highest for the Talent. Late appearing endoleaks, defined as a positive CT after a negative CT, were frequent. At 6 months, 44 (30%) of 147 type II endoleaks were newly diagnosed. The rates were 37 (35%) of 107 at 12 months, 15 (27%) of 56 at 2 years and 5 (25%) of 20 at 3 years. No conversions to open repair for type II endoleaks were noted in the first 4 years. The thrombus burden could not be determined in this analysis.

CONCLUSIONS

Type II endoleaks occur in nearly 15% of patients treated by EVAR. The early incidence varies only slightly with graft type. The long-term prevalence and clinical significance are masked by different treatment patterns, spontaneous resolution, newly evident endoleaks, and aneurysm size at initial treatment.

Flow Visualization in a Model of a Bifurcated Stent-Graft

PURPOSE

To use an in vitro flow model to investigate the flow patterns in a bifurcated stent-graft for abdominal aortic aneurysm (AAA) repair.

METHODS

Experiments were performed in an in vitro test rig incorporating a simplified non-planar model of an AAA. A two-component bifurcated device consisting of a stent structure and transparent polyurethane "graft" was deployed in the AAA model. Using a blood analogue fluid, a pulsatile blood flow waveform simulating resting flow condition was produced by means of a piston pump system. Flow patterns in the lateral and anteroposterior planes of the stent-graft were recorded and analyzed using flow visualization techniques.

RESULTS

The flow patterns within the stent-graft were complex and influenced by the geometry of the stent-graft itself, as well as that of the aortic neck and iliac vessels. Regions of flow separation, low velocity and stagnation, and slow oscillatory flow near the walls were seen in the main body of the stent-graft. Constriction at the stump in the contralateral limb resulted in flow disturbances and flow separation. Kinking at the junctions of stent segments and folding of the graft compounded these complex flow structures.

CONCLUSIONS

The flow structures within stent-grafts are complex, with features that may predispose to thrombus formation. Arterial geometry, including aortic neck angulation and iliac vessel tortuosity, and the design of the stent-graft are factors that influence hemodynamics and may impact the performance of aortic stent-grafts.

Past, Present, and Future Endograft Devices

Since the original descriptions of endovascular grafts for treatment of aneurysms, a number of devices and approaches have been developed. The following is a discussion summarizing the number of devices which have been developed and used in patients, as well as chosen the directions of this technology. The diversity of approach from an engineering and materials point of view speaks of the fact that opportunity exists for continued development in the future.

Endovascular Repair of Abdominal Aortic Aneurysms Using 3 Commercially Available Devices:Midterm Results

PURPOSE

To report the early and midterm results of 3 commercially available stent-grafts for abdominal aortic aneurysm (AAA) exclusion.

METHODS

Since fall 1999, 151 patients (137 men; mean age 74 years, range 54-88) have undergone AAA repair using 88 Ancure, 46 AneuRx, and 17 Excluder stent-grafts in elective procedures. All patients were followed clinically and underwent postoperative duplex ultrasound and/or computed tomographic angiography, which was repeated every 6 months.

RESULTS

The mean overall follow-up was 17 months (range 1-46). Initial technical failure was 3% (3/88) for Ancure versus 0% for AneuRx and Excluder. Primary endoleak occurred in 8% (7/88) of the Ancure patients versus 22% (10/46) for AneuRx and 6% (1/17) for Excluder (p=NS). Early (30-day) graft thrombosis (2/151, 1%) was seen only in the Ancure group. The perioperative complication rates (excluding endoleak and fever) were 22% (19/ 88) for Ancure, 15% (7/46) for AneuRx, and 0% for Excluder (p=NS). There was only 1 (0.7%) perioperative death in the series (Ancure patient). More ancillary procedures were performed in the Ancure group (p<0.05). Postoperatively, the size of the AAA decreased or remained unchanged in 76% for Ancure patients versus 75% for AneuRx and 64% for Excluder (p=NS). The incidences of late endoleak were 6% for Ancure, 2% for AneuRx, and 0% for Excluder (p=NS). The freedom from late endoleak at 3 years was 88% for Ancure and 97% for AneuRx (100% at 1 year for Excluder). Survival rates were similar. No AAA rupture was recorded.

CONCLUSIONS

The Ancure device has slightly higher overall perioperative complications and early technical failure than AneuRx or Excluder. All 3 devices are effective in preventing aneurysm rupture; the overall midterm survival rates, freedom of endoleak, and limb patency are somewhat similar.

Endovascular graft limb occlusion

Endovascular aneurysm repair (EVAR) has undergone a tremendous evolution in the nearly 15 years since it was first described. Continual refinement of the technology and techniques associated with EVAR and the respectable short-term results of this procedure led the United States Food and Drug Administration to approve several devices for the endovascular treatment of abdominal aortic aneurysm (AAA). There has been a corresponding rapid dissemination of this technology throughout the vascular surgery community in the United States. Availability and critical analysis of mid- and long-term follow-up data on the increasing number of patients who have undergone EVAR has begun to raise questions about the long-term durability and effectiveness of EVAR. Numerous complications of EVAR are now recognized and well described in the literature. One of these is graft limb dysfunction. Graft limb occlusion occurs in a significant number of patients and it is imperative that physicians who perform EVAR have a thorough understanding of this condition. There are a variety of factors that predispose patients to development of graft limb occlusion. These factors can be classified as either anatomic or graft-related. When patients present with graft limb occlusion, endovascular treatment is usually possible and it is highly effective. Some cases require traditional surgical treatment. Prevention of graft limb occlusion is of paramount importance. It can only be achieved with an aggressive search for graft limb compromise and liberal use of angioplasty and/or stenting at the time of graft implantation.