Endovascular Aneurysm Repair Devices Research Articles

Clinical Impact of Isolated Infrarenal Aortic Stenosis

Objectives: To evaluate early outcomes and short-term durability of thoracic stent cuffs in patients with abdominal aortic aneurysms (AAA) and infrarenal necks too large for standard endovascular aneurysm repair (EVAR) who were symptomatic, not suitable for open surgery, and could not wait for a custom fenestrated device to be created. Methods: From July 2010 to December 2012, 13 patients with juxtaor pararenal AAA underwent endovascular repair with thoracic aortic endografts as proximal aortic cuffs in conjunction with standard EVAR devices. The patients were symptomatic and were deemed unfit for open surgery due to severe cardiopulmonary and/or renal comorbidities. All patients had infrarenal neck diameters greater than the indications for use for standard aortic endografts. Primary end points were technical success (as defined by aneurysm exclusion without endoleak), follow-up aneurysm exclusion by computed tomographic angiogram, and 30-day and longterm mortality. Results: Thirteen patients (10 men, 3 women) with a mean age of 77.1 years underwent EVAR who presented with symptomatic juxtaor pararenal abdominal aortic aneurysms. The mean aneurysm size was 7.2 cm, and the mean infrarenal aortic neck diameter was 35.5 mm measured by centerline analysis. Technical success was achieved in 100% of cases. The 30-day mortality was 8% (one of 13 patients). At a mean follow-up of 524 days, there have been no endoleaks or other aneurysm related mortalities. There was one death due to stroke at 605 days postop. Conclusions: Complex endovascular repair of juxta and pararenal AAA using thoracic stents cuffs can be safely and successfully performed in symptomatic patients medically unfit for open repair. Using thoracic stent cuffs below the visceral vessels may reduce the complexity and possibly the risk of repair when compared with fenestrated endografts. These techniques can be used for urgent and emergent cases where the wait time for fenestrated technology is prohibitive. Although our results have demonstrated short-term success, long-term durability of this technique with further evaluation is required.

EVAR Deployment in Anatomically Challenging Necks Outside the IFU

Treatment of abdominal aortic aneurysms with high-risk anatomy (neck length <10-15 mm, neck angle >60°) using commercially available devices has become increasingly common with expanding institutional experience. We examined whether placement of approved devices in short angled necks provides acceptable durability at early and intermediate time points. A total of 218 patients (197 men, 21 women) at a single academic center underwent endovascular aneurysm repair (EVAR) with a commercially available device between January 2004 and December 2007. Available medical records, pre- and postoperative imaging, and clinical follow-up were retrospectively reviewed. Patients were divided into those with suitable anatomy (instructions for use, IFU) for EVAR and those with high-risk anatomic aneurysm characteristics (non-IFU). IFU (n = 143) patients underwent repair with Excluder (40%), AneuRx (34%), and Zenith (26%) devices, whereas non-IFU (n = 75) were preferentially treated with Zenith (57%) over Excluder (25%) and AneuRx (17%). Demographics and medical comorbidities between the groups were similar. Operative mortality was 1.4% (2.1% IFU, 0% non-IFU) with mean follow-up of 35 months (range 12-72). Non-IFU patients tended to have larger sac diameters (46.7% ≥60 mm) with shorter (30.7% ≤10 mm), conical (49.3%), and more angled (68% >60°) necks (all P < .05 compared with IFU patients). Operative characteristics revealed that the non-IFU patients were more likely to be treated utilizing suprarenal fixation devices, to require placement of proximal cuffs (13.3% vs 2.1%, P = .003), and needed increased fluoroscopy time (31 vs 25 minutes, P = .02). Contrast dose was similar between groups (IFU = 118 mL, non-IFU = 119 mL, P = .95). There were no early or late surgical conversions. Rates of migration, endoleak, need for reintervention, sac regression, and freedom from aneurysm-related death were similar between the groups (P > .05). EVAR may be performed safely in high-risk patients with unfavorable neck anatomy using particular commercially available endografts. In our experience, the preferential use of active suprarenal fixation and aggressive use of proximal cuffs is associated with optimal results in these settings. Mid-term outcomes are comparable with those achieved in patients with suitable anatomy using a similar range of EVAR devices. Careful and mandatory long-term follow-up will be necessary to confirm the benefit of treating these high-risk anatomic patients.

EVAR Deployment in Anatomically Challenging Necks Outside the IFU

Treatment of abdominal aortic aneurysms with high-risk anatomy (neck length <10-15 mm, neck angle >60°) using commercially available devices has become increasingly common with expanding institutional experience. We examined whether placement of approved devices in short angled necks provides acceptable durability at early and intermediate time points. A total of 218 patients (197 men, 21 women) at a single academic center underwent endovascular aneurysm repair (EVAR) with a commercially available device between January 2004 and December 2007. Available medical records, pre- and postoperative imaging, and clinical follow-up were retrospectively reviewed. Patients were divided into those with suitable anatomy (instructions for use, IFU) for EVAR and those with high-risk anatomic aneurysm characteristics (non-IFU). IFU (n = 143) patients underwent repair with Excluder (40%), AneuRx (34%), and Zenith (26%) devices, whereas non-IFU (n = 75) were preferentially treated with Zenith (57%) over Excluder (25%) and AneuRx (17%). Demographics and medical comorbidities between the groups were similar. Operative mortality was 1.4% (2.1% IFU, 0% non-IFU) with mean follow-up of 35 months (range 12-72). Non-IFU patients tended to have larger sac diameters (46.7% ≥60 mm) with shorter (30.7% ≤10 mm), conical (49.3%), and more angled (68% >60°) necks (all p < .05 compared with IFU patients). Operative characteristics revealed that the non-IFU patients were more likely to be treated utilizing suprarenal fixation devices, to require placement of proximal cuffs (13.3% vs. 2.1%, p = .003), and needed increased fluoroscopy time (31 vs. 25 minutes, p = .02). Contrast dose was similar between groups (IFU = 118 mL, non-IFU = 119 mL, p = .95). There were no early or late surgical conversions. Rates of migration, endoleak, need for reintervention, sac regression, and freedom from aneurysm-related death were similar between the groups (p > .05). EVAR may be performed safely in high-risk patients with unfavorable neck anatomy using particular commercially available endografts. In our experience, the preferential use of active suprarenal fixation and aggressive use of proximal cuffs is associated with optimal results in these settings. Mid-term outcomes are comparable with those achieved in patients with suitable anatomy using a similar range of EVAR devices. Careful and mandatory long-term follow-up will be necessary to confirm the benefit of treating these high-risk anatomic patients.

Limitations of Current EVAR Endografts and Potential Solutions for Their Deficiencies

All current endovascular aneurysm repair (EVAR) devices have defined limitations that prevent the endovascular therapist from using them to treat all forms of aortoiliac aneurysm disease. Short, angulated infrarenal aortic neck pathology, occlusive disease in iliac access arteries, need for preservation of important branch vessel arterial flow, endograft migration, and endoleak all represent major impediments for successful EVAR. Need for secondary intervention after EVAR in a significant number of patients has detracted from universal acceptance for this therapy. New devices in manufacturers' pipelines may provide solutions for many of the current EVAR device deficiencies. As these new devices become more complex, meticulous patient follow-up to verify anticipated outcomes and new training paradigms for the future endovascular therapist will be required.

Cost Impact of Extension Cuff Utilization During Endovascular Aneurysm Repair

Modular stent-graft systems for endovascular aneurysm repair (EVAR) most often require two to three components, depending on the device. Differences in path lengths and availability of main body systems often require additional extensions for appropriate aneurysm exclusion. These additional devices usually result in added expenses and can affect the financial viability of an EVAR program within a hospital. The purpose of this study was to analyze the use of extensions during EVAR, focusing on incidence, clinical impact, and financial impact, as well as determining the associated cost differences between two- and three-component EVAR device systems. We reviewed available clinical data, images, and follow-up of 218 patients (203 males and 15 females, mean age: 74 ± 9 years) who underwent elective EVAR at a single academic center from 2004 to 2007. Patients were divided into two groups: patients undergoing EVAR using the standard number of pieces, that is, no extensions used (group A, n = 98), and those needing proximal or distal extensions during the index procedure (group B, n = 120). Both groups were similar in terms of demographics; preoperative characteristics, including aneurysm morphology; as well as intraoperative, postoperative, and midterm outcomes. Overall, 30-day operative mortality was 1.4%, with a mean follow-up of 24 months. Group A patients underwent repair with two-piece modular devices 41% of the time and three-piece systems 59% of the time, whereas group B patients underwent repair with two-piece modular systems 82% of the time and three-piece modular systems 18% of the time. The number of additional extensions per patient ranged from one to four (median: one piece). There was a 30% cost increase in overall mean device-related cost when using extensions versus the standard number of pieces (group A: $13,220 vs. group B: $17,107, p < 0.01). Clinical midterm aneurysm-related outcomes after EVAR in patients who required additional extensions was comparable with those treated with the standard number of pieces. An increased number of extensions led to increased costs and could have potentially been minimized with appropriate preoperative planning or device selection. Consideration should be made toward per-case pricing instead of per-piece pricing to further improve cost efficiency without compromising long-term patient outcomes.

Predictors of Abdominal Aortic Aneurysm Sac Enlargement After Endovascular Repair

Conclusion: In the Unites States compliance with endovascular aneurysm repair (EVAR) device guidelines is low. Rates of post-EVAR aneurysm sac enlargement are high. Summary: Companies marketing EVAR devices measure technical factors such as delivery accuracy, sealing ability, and fixation strength in the laboratory. These measurements are used to generate instructions for use (IFU) that are packaged with each EVAR device sold in the United States. The randomized trials comparing EVAR with open aneurysm repair have used EVAR devices in accordance with IFUs. Many physicians may perform EVAR without adherence to IFUs. It is unknown how often EVAR is performed outside the IFU for the device and longer-term results of EVAR performed outside IFUs are unknown. However, a significant portion of late deaths after EVAR are due to aneurysm rupture (De Bruin JL et al, N Engl J Med 2010;362;1881-9, and Wyss TR, Ann Surg 2010;252;805-12) and aneurysm rupture after EVAR is linked with aneurysm sac enlargement. The authors sought to determine compliance with IFUs in EVAR placement over the last decade and to determine relationships between anatomic characteristics at baseline of aorta and iliac arteries and the subsequent incidence of aortic aneurysm sac enlargement after EVAR. The authors examined patients undergoing EVAR between January 1, 1999, and December 31, 2008, using a medical imaging repository at M2S, Inc. (West Lebanon, NH). The deidentified data on all patients in the prospectively acquired M2S database was used for those who underwent a CT scan before EVAR and had at least one CT scan after EVAR between 1999 and 2008 in the United States. Patients were excluded if they underwent an EVAR in the context of premarketing or postmarketing studies in which M2S served as a core imaging laboratory. Preoperative aorta iliac anatomic characteristics were reviewed for each patient. The specific endovascular device implanted was not available from this database. Morphologic measurements were therefore compared with the most liberal and most conservative published anatomic guidelines stated in manufacturer's IFUs. Primary outcome was post-EVAR aneurysm sac enlargement >5 mm. There were 10,228 patients included in the database and used for the study. Of these, 59% had a maximum abdominal aortic aneurysm diameter below the 55-mm threshold at which intervention is recommended over surveillance. Forty-two percent of patients had anatomy that met the most conservative definition of IFUs and 69% met the most liberal definition of device IFUs. The 5-year post-EVAR rate of AAA sac enlargement was 41%. Independent predictors of AAA sac enlargement included age >80 years, endoleak, aortic neck diameter >28 mm, aortic neck angle >60°, and common iliac artery diameter >20 mm. Comment: Some physicians placing EVAR devices may be acting in what some could consider an irresponsible fashion. In this study, most EVAR devices were placed in abdominal aortic aneurysms that were below the threshold for intervention justified by randomized trials. Even with the most liberal definition of IFUs almost one-third of devices were placed outside manufacturer's recommendations, and in this database, >40% of aortas treated with EVAR had aneurysm sac enlargement at 5 years. The data are disturbing and raise significant questions about aneurysm treatment in the United States and about long-term risk of aneurysm rupture in patients treated with EVAR in the United States. Physicians placing EVAR devices need to do better job of policing themselves. If not, one can be sure someone else will! One can only speculate that it won't take long for the malpractice attorneys to stumble on to this.

The effect of warfarin therapy on endoleak development after endovascular aneurysm repair (EVAR) of the abdominal aorta

The presence of an endoleak after endovascular abdominal aortic aneurysm (AAA) repair (EVAR) may predispose to sac expansion and potential sac rupture. The incidence of endoleak after AAA repair can be as high as 20% to 30%. We investigated whether warfarin anticoagulation was an independent risk factor for endoleak after EVAR for AAA. All AAA patients who underwent elective EVAR were prospectively followed-up. Data for demographics, clinical comorbidities, outcomes, EVAR devices, and anticoagulation methods were recorded. All patients underwent routine follow-up at 1, 6, and 12 months and annually thereafter. Computed tomography angiography (CTA) with 3-dimensional (3D) volumetric analysis was also completed. During a 7-year period, 127 consecutive patients with infrarenal AAAs who underwent EVAR were monitored for a mean of 2.14 years. The average age at the time of EVAR was 73.8 years. Warfarin therapy alone was administered to 24 patients, and anticoagulation with antiplatelet therapy alone was administered to 103. During the study period, 38 (29.9%) endoleaks were documented. The overall endoleak rate was 13 of 24 in the warfarin group and 25 of 103 in the antiplatelet group (P = .004). CTA 3D volumetric aneurysm sac analysis showed an increase of 16.09% in the warfarin study group and a reduction of 9.71% in the antiplatelet group (P = .04). Anticoagulation with warfarin appears to be linked to an increased risk for the development of endoleak after EVAR, specifically type II. Volumetric analysis showed warfarin therapy also contributed to persistent aneurysm sac expansion. These data suggest that patients who require warfarin anticoagulation for other indications should be advised that they might be at an increased risk for the development of endoleaks, subsequent secondary interventions, persistent sac expansion, and possible delayed sac rupture.

AAA Stent–Grafts: Past Problems and Future Prospects

Endovascular aneurysm repair (EVAR) has quickly gained popularity for infrarenal abdominal aortic aneurysm repair during the last two decades. The improvement of available EVAR devices is critical for the advancement of patient care in vascular surgery. Problems are still associated with the grafts, many of which can necessitate the conversion of the patient to open repair, or even result in rupture of the aneurysm. This review attempts to address these problems, by highlighting why they occur and what the failings of the currently available stent grafts are, respectively. In addition, the review gives critical appraisal as to the novel methods required for dealing with these problems and identifies the new generation of stent grafts that are being or need to be designed and constructed in order to overcome the issues that are associated with the existing first- and second-generation devices.

Use of Non-randomised Evidence Alongside Randomised Trials in a Systematic Review of Endovascular Aneurysm Repair: Strengths and Limitations

Objective: To assess whether limitations of randomised controlled trials (RCTs) of endovascular aneurysm repair (EVAR) can be addressed by evidence from non-randomised studies. Design: Analysis of data from a systematic review. Methods: We conducted a review of EVAR versus open repair or non-surgical management of abdominal aortic aneurysms. In addition to RCTs, we included pre-specified registries of EVAR and open repair. Results: The six included RCTs randomised patients in 2003 and earlier. Of the three registries included, one contributed data on a large (>8000) sample of patients treated with newer generation EVAR devices and followed up for up to 8 years. However, treatment dates of these patients overlapped with those of the RCTs. The other registries were of limited usefulness. A large (>45,000) controlled observational study published while the review was in progress broadly supported the findings of RCTs comparing EVAR with open surgery. A comparison of outcomes across all studies did not support the hypothesis that the findings of the RCTs are no longer representative of clinical practice. Conclusions: Both randomised and non-randomised sources of evidence have strengths and weaknesses for assessing the effectiveness of EVAR. Further research should explore the optimum use of registry data, including patient-level analyses.

Use of Non-randomised Evidence Alongside Randomised Trials in a Systematic Review of Endovascular Aneurysm Repair: Strengths and Limitations

To assess whether limitations of randomised controlled trials (RCTs) of endovascular aneurysm repair (EVAR) can be addressed by evidence from non-randomised studies. Analysis of data from a systematic review. We conducted a review of EVAR versus open repair or non-surgical management of abdominal aortic aneurysms. In addition to RCTs, we included pre-specified registries of EVAR and open repair. The six included RCTs randomised patients in 2003 and earlier. Of the three registries included, one contributed data on a large (>8000) sample of patients treated with newer generation EVAR devices and followed up for up to 8 years. However, treatment dates of these patients overlapped with those of the RCTs. The other registries were of limited usefulness. A large (>45,000) controlled observational study published while the review was in progress broadly supported the findings of RCTs comparing EVAR with open surgery. A comparison of outcomes across all studies did not support the hypothesis that the findings of the RCTs are no longer representative of clinical practice. Both randomised and non-randomised sources of evidence have strengths and weaknesses for assessing the effectiveness of EVAR. Further research should explore the optimum use of registry data, including patient-level analyses.

Anatomic Suitability of Ruptured Abdominal Aortic Aneurysms for Endovascular Repair

Mortality from ruptured abdominal aortic aneurysms (rAAAs) remains high despite improvements in anesthesia, postoperative intensive care, and surgical techniques. Recent small series and single-center experiences suggest that endovascular aneurysm repair (EVAR) for rAAAs is feasible and may improve short-term survival. However, the applicability of EVAR to all cases of rAAA is unknown. The purpose of this study was to investigate the anatomical suitability of ruptured aneurysms for EVAR as determined by preoperative cross-sectional imaging. A contemporary consecutive series of rAAAs presenting to a tertiary academic center was retrospectively reviewed. Preoperative radiographic imaging was reviewed and assessed for endovascular compatibility based on currently available EVAR devices. Patients with aneurysm morphology demonstrating neck diameter >32 mm, neck length <10 mm, neck angulation >60 degrees, severe iliac tortuosity, or external iliac diameter <6 mm were deemed noncandidates for EVAR. Forty-seven rAAAs were treated over a 10-year period, with 47% of patients presenting with free rupture and 60% of patients transferred from outside hospitals. Five (11%) patients were treated with EVAR, all over the past 2 years, while the remaining 42 patients underwent open repair. Preoperative imaging was available for review in 43 (91%) patients, and morphological measurements indicated that 49% would have been candidates for EVAR with currently available devices. Criteria precluding EVAR in this cohort were inadequate neck length in 73%, unsuitable iliac access in 23%, large neck diameter in 18%, and severe neck angulation in 14%. Overall 30-day mortality was 34%, and 1-year mortality was 42%. Candidates for EVAR were more likely than non-EVAR candidates to be male (95% vs. 68%, p = 0.046) and to have smaller sac diameters (7.0 vs. 8.5 cm, p = 0.02) and longer neck lengths (24.1 vs. 8.6 mm, p < 0.0001); less likely to have a >60 degree angulated neck (10% vs. 45%, p = 0.0002), larger external iliac diameter (8.9 vs. 7.3 mm, p = 0.015), and less blood loss during surgical repair (2.4 vs. 6.0 L, p = 0.02); and more likely to be discharged home (71% vs. 25%, p = 0.05). There were no differences in 30-day, 1-year, or overall mortality between candidates for EVAR and noncandidates. Only 49% of patients with rAAAs in this consecutive series were found to be candidates for EVAR with conventional stent-graft devices. Differences in demographics, aneurysm morphology, and outcomes between candidates and noncandidates undergoing open repair suggest that differential risks apply to ruptured aneurysm patients. Protocols and future reports of EVAR for rAAAs should be tailored to these results. Device and technique modifications are necessary to increase the applicability of EVAR for rAAAs.

Mid-term results of patients undergoing endovascular aortic aneurysm repair

BackgroundThe utilization of endovascular aneurysm repair (EAR) is increasing significantly; however, few papers have outlined mid-term outcomes. MethodsPatients undergoing EAR with an AneuRx endograft between September 1997 and May 2001 were evaluated. Mean follow-up was 20.7 ± 11.9 (SD) months. ResultsIn all, 101 EAR devices were successfully deployed in 105 attempts. Four open conversions (2 acute, 2 delayed) were performed for complications of EAR. Technical, clinical, and 1 to 3 year continuing success rates were 75%, 73%, and 78% to 83%. When divided by the median date, significantly fewer patients in the later group required secondary procedures compared with the early group. Vascular insufficiency occurred in 12 patients; 11 were treated with a secondary procedure. For 9 type I and 9 type II persistent endoleaks, secondary procedures were attempted and successful in 10 patients. Of successful EAR deployments, including secondary interventions, 85% demonstrated no persistent leak, rupture, increase in aneurysm size, or migration at most recent follow-up. Conclusions:EAR is successful in selected individuals; however, continuing follow-up is of paramount importance.

An Appraisal of the Results of a Six-Year Tuberculin and Mass X-Ray Survey of the Population of Asuncion: Based on More Than 100,000 Tests

The aim of this study is to present an easy and quick technique for embolization of the inferior mesenteric artery (IMA) during endovascular aneurysm repair (EVAR).We performed IMA embolization using a conventional EVAR device alone with the femoral artery approach during EVAR, which has not been reported previously. First, a 16F or 18F DrySeal Sheath is inserted from the femoral artery into the site around the IMA. Second, cannulation is performed in the IMA with an angiography catheter having a 0.038-inch inner lumen that is used for gate cannulation during EVAR. Third, IMA embolization is performed using the Amplatzer Vascular Plug 4 (AVP4). The use of the DrySeal Sheath facilitates cannulation of the IMA, and its combination with a stent-graft balloon allows the AVP4 to be placed at the root of the IMA without deviation of the catheter. The success rate of the procedure was 90.9% (30/33 cases). The median procedure time was 11.6 min. No complications due to IMA embolization were noted.This procedure enables safe and quick placement of the AVP4 in the IMA using the catheter insertion approach from the femoral artery, which has been conventionally regarded as difficult.