Stent-graft migration following endovascular repair of aneurysms with large proximal necks: anatomical risk factors and long-term sequelae

Impact of patient demographics and intraoperative characteristics on abdominal aortic aneurysm sac following endovascular repair

BACKGROUND

Endovascular aortic repair (EVAR) has become the preferred treatment for abdominal aortic aneurysm (AAA). Its main aim is to seal the perfusion of the aneurysmal sac and, thus, induce sac regression and subsequent aortic remodelling. Aneurysmal sac regression has been linked to the short- and long-term clinical outcomes post-EVAR. It has also been shown to be influenced by endograft device choice, with several of these available commercially. This review summarises and discusses current evidence on the influence of pre- and intraoperative factors on sac regression. Additionally, this review aims to highlight the device-specific variations in sac regression to provide an overall holistic approach to treating AAAs with EVAR.

METHODS

A comprehensive literature search was conducted using multiple electronic databases to identify and extract relevant data.

RESULTS

Female sex, >70 mm original sac diameters, higher pre-procedural fibrinogen levels, smoking and low intra-aneurysmal pressure were found to positively impact sac regression. Whereas renal impairment, ischemic heart disease, high intra-aneurysmal pressure and aneurysm neck thrombus negatively influenced sac regression. Patent lumbar arteries, age, statins and hypercholesterolaemia displayed conflicting evidence regarding sac regression. Regarding the EVAR endografts compared, newer generation devices such as the Anaconda mainly showed the most optimal results.

CONCLUSION

Sac regression following EVAR in AAA is an important prognostic factor for morbidity and mortality. Nevertheless, several pre- and intraoperative factors can have an influence on sac regression. Therefore, it is necessary to take them into account when assessing AAA patients for EVAR to optimise outcomes. The choice of EVAR stent-graft can also affect sac regression, with evidence suggesting that the Fenestrated Anaconda is associated with the most favourable results.

Two-Year Outcomes of the Nellix EndoVascular Aneurysm Sealing System for Treatment of Abdominal Aortic Aneurysms

Purpose: To analyze the 2-year outcomes of endovascular aneurysm sealing (EVAS) according to 2 versions of the instructions for use (IFU). Methods: A retrospective study was conducted involving 355 consecutive patients treated with the first-generation EVAS device from April 2013 to December 31, 2015, at 3 high-volume centers. Out of 355 patients treated with EVAS, 264 were elective asymptomatic infrarenal EVAS procedures suitable for analysis. In this cohort, 168 (63.3%) patients were treated within the IFU 2013 criteria; of these 48 (18.2%) were in compliance with the revised IFU 2016 version. Results: Overall technical success was 98.2% (165/168) in the IFU 2013 group and 97.9% (47/48) in the IFU 2016 subgroup (p=0.428). The 2-year freedom from reintervention estimates were 89.7% (IFU 2013) and 95.7% (IFU 2016), with significantly more reinterventions in the first 45 cases (p=0.005). The stenosis/occlusion estimates were 6.5% (IFU 2013) and 4.2% (IFU 2016; p=0.705). Nine (5.4%) endoleaks (8 type Ia and 1 type Ib) were observed within the IFU 2013 cohort; 3 (2.1%) were in the IFU 2016 subgroup (p=0.583). Migration ≥10 mm or ≥5 mm requiring intervention was reported in 12 (7.1%) patients in the IFU 2013 cohort but none within the IFU 2016 subgroup. Ten (6.0%) patients demonstrated aneurysm growth in the IFU 2013 cohort, of which 2 (4.2%) were in the IFU 2016 subgroup. Overall survival and freedom from aneurysm-related death estimates at 2 years were 90.9% and 97.6% in the IFU 2013 cohort (IFU 2016: 95.5% and 100.0%). The prevalence of complications seemed lower within IFU 2016 without significant differences. Conclusion: This study shows acceptable 2-year results of EVAS used within the IFU, without significant differences between the 2 IFU versions, though longer follow-up is indicated. The refined IFU significantly reduced the applicability of the technique.

Contemporary Results of Endovascular Repair of Isolated Abdominal Aortic Dissection with Unibody Bifurcated Stent Grafts

OBJECTIVES

To report the midterm safety and efficacy of the Aegis™-B (Microport, Shanghai, China) unibody bifurcated stent graft for endovascular treatment of isolated abdominal aortic dissection (IAAD).

BACKGROUND

Isolated abdominal aorta dissection (IAAD) is a rare event. Endovascular stent grafts seem to offer an efficient therapeutic approach to treat IAAD. However, the relatively small diameter of the infrarenal aorta and aortic bifurcation remains the main anatomical limitation to endovascular repair.

METHODS

Between 2008 and 2015, we retrospectively evaluated 32 IAAD patients (21 men; mean age 58 ± 18 years), who underwent endovascular repair using Aegis™-B unibody bifurcated stent graft. Narrow proximal landing zone and narrow distal aorta was present in 11 (34.4%) patients and 10 (31.3%) patients, respectively. In the follow-up period, aortic remodeling was observed with computed tomography angiography.

RESULTS

All patients were treated by endovascular means, with a primary technical success rate of 100%. During a mean follow-up period of 30.71 ± 16.36 months (range, 8-56 months), no death, rupture, stent fracture, material failure, or device migration was observed. Complete false lumen thrombosis was observed in all patients at 1 year, and all patients were free from false lumen growth in the follow-up.

CONCLUSIONS

Endovascular treatment of IAAD using the Aegis™-B system appears to be safe and effective. Results from this study suggest this algorithm can provide stable, secure fixation for IAAD patients with narrow proximal landing zone, and distal aorta.

Management of Abdominal Aortic Aneurysm: A Decade of Progress

Since the world was first introduced to the concept of endovascular aneurysm repair by Parodi's landmark procedures in 1990, stent-grafts have assumed a prominent role in the management of abdominal aortic aneurysm. Most modern systems are trackable, accurate, and secure. The resulting endovascular procedure is safe, durable, effective, and versatile. Perhaps the most significant increment in the applicability of the endovascular technique was achieved by the development of bifurcated stent-grafts, which dispensed with inadequate distal aortic implantation sites. Additional branches and fenestrations now permit endovascular repair in cases of thoracoabdominal, pararenal, juxtarenal, and bilateral iliac aneurysms. These advances in device performance have been accompanied by a rapid dissemination of necessary skills, leading to the development of a new superspecialty of vascular therapy, with elements of vascular surgery, interventional radiology, and interventional cardiology.

Is Neck Dilatation After Endovascular Aneurysm Repair Graft Dependent?

Long-term success of endovascular aneurysm repair (EVAR) relies on a stable proximal neck. The authors' goal was to determine whether neck dilatation after EVAR varies among 4 different endografts and whether it is related to complications of the proximal neck. Core laboratory data from 4 phase II trials of aortic endografts were analyzed for neck diameter changes over time. Patients who had at least 24 months' follow-up were included in the analysis. Neck measurement methodology varied among the 3 core labs used. Values are reported within the parameters used by each lab. Short-axis neck diameter close to 5 mm below the renal arteries, when available, was used for longitudinal comparisons. Dilation was defined as an enlargement of 3 mm or more from the first postoperative scan to the last available follow-up for each patient. Graft migration and late proximal endoleaks were determined by the individual core labs. A limited number of Lifepath grafts had most recent follow-up measurements performed by the authors. Results were compared by using Student's t test, chi-square analysis, and the Pearson correlation coefficient. Postoperative measurements from 729 EVAR patients were examined. Follow-up ranged from 24 to 60 months for 229 Ancure (Guidant) and 258 AneuRx (Medtronic) patients, and from 24 to 36 months for 211 Excluder (Gore) and 31 first-generation Lifepath (Edwards) patients. Neck dilation was noted in 124 patients (17.0%) and did not differ significantly among graft types. The incidences of late proximal endoleaks were similar among graft types, but rates of migration differed (p= 0.01). Dilation was associated with migration in Ancure (p=0.03) and Excluder (p=0.02) grafts. Late proximal endoleaks were seen in 4.1% of patients with and in 0.7% of patients without dilation (p=0.001). Patients with initial neck diameter >25 mm had significantly less dilatation than those with smaller necks (p<0.001). The incidence of neck dilation approached 20% in all EVAR patients after 24 months and was not significantly different among graft types. Neck dilation of 3 mm or more appears to be one risk factor for migration and late proximal endoleak.

Device-Specific Resistance to in Vivo Displacement of Stent-Grafts Implanted with Maximum Iliac Fixation

Purpose:

To compare the in vivo device-specific downward displacement force of various externally supported endografts implanted with maximum iliac fixation.

Methods:

Twenty female sheep had aneurysms created with a graft patch in the infrarenal aorta. In 12 animals, a fully supported modular bifurcated stent-graft [AneuRx (n=4), Talent (n=4), or Zenith (n=4)] was deployed; in the other 8, a bifurcated aortic graft was surgically anastomosed to the infrarenal aorta. All grafts were displaced in vivo by applying downward traction to a guidewire brought out both femoral arteries. The peak force to cause initial stent-graft migration or disruption of the sutured anastomosis was recorded and compared.

Results:

There was no difference in animal size, aortic neck diameter or length, aneurysm size, or iliac artery diameter for animals receiving the AneuRx, Talent, or Zenith stent-grafts and those undergoing surgical repair. The mean length of iliac fixation was 31.0±0.3 mm, 30.8±0.5 mm, and 31.3±0.6 mm for the AneuRx, Talent, and Zenith devices, respectively (p=NS). Peak force to initiate migration was 30.2=5.5 N (range 25–38) for the AneuRx, 44.8±5.5 N (range 40–53) for the Talent, 46.7±5.4 N (range 38–55) for the Zenith, and 40.6±7.5 N (range 31–50) for the surgical anastomosis (p=0.01). There was no difference detected in the peak force to initiate migration between the suprarenally affixed Talent and Zenith stent-grafts and the surgical anastomosis (p=0.55).

Conclusion:

Devices with a suprarenal component require significantly greater force to cause downward displacement compared to infrarenal devices. The force required to displace a suprarenal device with maximal iliac fixation was equivalent to the force required to disrupt a surgical anastomosis.

Systematic review and meta-analysis of migration after endovascular abdominal aortic aneurysm repair

Aim

To identify patients who are under higher threat for migration because of an old generation stent graft application.

Methods

A systematic review and meta-analysis of the literature was undertaken to identify all studies which included older generation endografts and data reporting on graft migration after EVAR. Outcome data were pooled and combined, and were calculated using fixed or random effects models.

Results

From 2000 to 2014, 22 retrospective studies were identified reporting on stent- graft migration after EVAR (8.6%). From those patients, 39% received re-intervention with the mean time of identification ranging from 12 to 36 months. Six of these retrospective nonrandomized studies were eligible for meta-analysis. AAA diameter (AAA diameter: 0.719 mm; 95% confidence interval [CI]: 0.00065–1.4384 mm; p = 0.00497) and neck length (neck length: 4.36 mm; 95% CI: 1.3277–7.394; p = 0.0048) were the only significant factors associated with stent- graft migration. Neck diameter and neck angulation did not have any important influence on stent-graft migration.

Conclusions

Patients with large AAA and short necks who were treated with older generation stent grafts such as AneurX and Talent are in higher risk for endograft migration than others. Stent- graft migration consists of an insidious and underestimated threat.

Endovascular versus open repair of ruptured abdominal aortic aneurysms

Although major improvement has occurred to make elective repair of abdominal aortic aneurysms a safe procedure, the incidence of ruptured abdominal aortic aneurysms and mortality rates are still disappointing. Endovascular abdominal aortic aneurysm repair has produced quantum changes in aneurysm treatment. The successful application of the endovascular approach for the treatment of abdominal aortic aneurysms in the elective setting has prompted a strong interest regarding its possible use in dealing with the long-standing challenge of a ruptured abdominal aortic aneurysm. Since the first report, several centers have reported results and a wide spectrum of opinion regarding its application, with special consideration to logistical and practical barriers for appropriate utilization. The purpose of this article is to review all the available literature on the endovascular repair of ruptured abdominal aortic aneurysms and to analyze the most recent trends in their management, with special consideration given to comparing results of conventional and endovascular approaches.

Early results of the Endurant endograft system in patients with friendly and hostile infrarenal abdominal aortic aneurysm anatomy

OBJECTIVE

To evaluate and compare the outcome after endovascular abdominal aortic aneurysm repair (EVAR) with the newly released Endurant endograft system in patients with different aortoiliac anatomic characteristics.

METHODS

We conducted a prospective observational study assigning patients with infrarenal abdominal aortic aneurysm (AAA) treated with the Endurant endoprosthesis from February 2009 to March 2010. Two groups were studied, according to the presence of a friendly (group I [GI] = 43) or hostile (group II [GII] = 34) infrarenal aortoiliac anatomy. Hostile profile was defined as any (or combination) of the following measurements: 5 mm ≤ proximal neck length (Lpr) ≤ 12 mm, 60° < proximal neck angle (A°pr) ≤ 90° and 60° < any iliac axis angle (A°iliac) ≤ 90°. Primary end points included technical and clinical success, freedom from early or late secondary interventions, any type of endoleak, and aneurysm-related death. All outcome measures were calculated using the Kaplan-Meier method and the log rank test was applied for comparisons between the groups.

RESULTS

The mean comorbid severity scoring was higher in GII (P = .018). The mean follow-up period in GI and GII was 12.9 ± 3.9 months (± SD, range: 6.4-19.8) and 12.4 ± 4 months (range: 4.2-19.6), respectively. Two unplanned conversions to aortouniiliac configurations were required in GI. The technical success rate in GI and GII was 95.4% and 100%, respectively. The requirement for intentional occlusion of the internal iliac artery, the requirement for cross-limb technique, the necessity of troubleshooting techniques, the procedure and radiation times, the frequency of postimplantation syndrome, and mean hospital stay were significantly higher in GII (P = .028, P = .013, P = .005, P = .037, P < .001, P = .032, P = .021, respectively). Two patients of GI died in the early postoperative period (one aneurysm but not device-related death), whereas no deaths in GII were recorded, yielding an overall 30-day mortality rate of 2.3%. No type I/III endoleaks were recorded up to the end of the study. Freedom from any type of endoleak, early or late secondary interventions, and aneurysm-related death at 12 months were found in 93.2%, 87.1%, and 93.3% of GI patients; respective values for GII were 86% (P = .21), 93.4% (P = .066), and 93.4%. The clinical success rate was 82.1% and 100% at 12 months for GI and GII, respectively.

CONCLUSIONS

Early (12 months) results suggest similar clinical performance of the Endurant stent graft system in endovascular treatment of AAAs with friendly and hostile anatomies, however, demonstrating more intra- and perioperative adversities for the last group. Larger prospective studies or even randomized trials comparing different new generation graft models are required to evaluate the comparable long-term results and possible expansion of EVAR indications for this specific endograft in adverse anatomies.

Gender bias in studies for Food and Drug Administration premarket approval of cardiovascular devices

BACKGROUND

Cardiovascular devices can have different safety and effectiveness profiles in men and women. The type and quality of sex-specific data reviewed by the Food and Drug Administration (FDA) before approval of these devices are unknown.

METHODS AND RESULTS

We performed a systematic review of the demographics, comments on gender bias, and analysis of results by sex for 78 high-risk cardiovascular devices that received premarket approval by the FDA between 2000 and 2007. FDA summaries of evidence did not report sex of enrollees in 34 (28%) of 123 studies. For studies reporting sex distribution, the study populations were, on average, 67% men. There was no increase in the enrollment of women over time. Explanations for the relatively low percentage of women often stated that the trials reflected either underlying disease distribution or referral rates for similar procedures or that the sex distribution reflected similar or previous trials. Forty-one percent of studies included a gender bias comment or analysis, and 12 (26%) of 47 of these analyses identified some difference in device safety or effectiveness by sex.

CONCLUSIONS

There is a lack of sex-specific safety and effectiveness data for high-risk cardiovascular devices before FDA approval. The justifications for this lack of evidence may perpetuate the status quo. More rigorous FDA requirements for sex-specific data before device approval could present an opportunity to improve cardiovascular outcomes.

Fatores envolvidos na migração das endopróteses em pacientes submetidos ao tratamento endovascular do aneurisma da aorta abdominal

A migração da endoprótese é complicação do tratamento endovascular definida como deslocamento da ancoragem inicial. Para avaliação da migração, verifica-se a posição da endoprótese em relação a determinada região anatômica. Considerando o aneurisma da aorta abdominal infrarrenal, a área proximal de referência consiste na origem da artéria renal mais baixa e, na região distal, situa-se nas artérias ilíacas internas. Os pacientes deverão ser monitorizados por longos períodos, a fim de serem identificadas migrações, visto que estas ocorrem normalmente após 2 anos de implante. Para evitar migrações, forças mecânicas que propiciam fixação, determinadas por características dos dispositivos e incorporação da endoprótese, devem predominar sobre forças gravitacionais e hemodinâmicas que tendem a arrastar a prótese no sentido caudal. Angulação, extensão e diâmetro do colo, além da medida transversa do saco aneurismático, são importantes aspectos morfológicos do aneurisma relacionados à migração. Com relação à técnica, não se recomenda implante de endopróteses com sobredimensionamento excessivo (> 30%), por provocar dilatação do colo do aneurisma, além de dobras e vazamentos proximais que também contribuem para a migração. Por outro lado, endopróteses com mecanismos adicionais de fixação (ganchos, farpas e fixação suprarrenal) parecem apresentar menos migrações. O processo de incorporação das endopróteses ocorre parcialmente e parece não ser suficiente para impedir migrações tardias. Nesse sentido, estudos experimentais com endopróteses de maior porosidade e uso de substâncias que permitam maior fibroplasia e aderência da prótese à artéria vêm sendo realizados e parecem ser promissores. Esses aspectos serão discutidos nesta revisão.

Early in Vivo Analysis of an Endovascular Stapler During Endovascular Aneurysm Repair

The objective of this article is to describe the use and technique of a novel endostapling device used in an in vivo animal model. Six ovine underwent implantation of a Dacron endograft into the thoracic aorta followed by placement of endoclips proximally and distally. The animals were survived 35 days to evaluate the performance and safety of the endoclip in an animal model prior to clinical trials. The mean time for securing both the proximal and the distal anastomosis was 22 minutes (range 17–31 minutes). All staples were deployed, without the need for repositioning, on the first attempt. There were no complications related to the implant procedure or indwelling clips. Additionally, no endograft migration occurred. At the time of expiant, staples were evaluated for depth of penetration and accuracy of placement. The staples had fully penetrated the endograft and vessel wall through the adventitia in 89% (64 of 72) of clips deployed. The staples were placed accurately, within 10 mm of the endograft proximal and distal attachments in 94% (68 of 72) of the clips deployed. Furthermore, endothelialization of the staples was present without surrounding thrombus. Implant sites were scored as normal without surrounding tissue damage by an independent pathologist. The endoclip performed well in creating proximal and distal fixation of the endograft. There were no adverse outcomes related to the endostaple. Future clinical trials should be undertaken to assess its clinical utility during endovascular aneurysm repair.

Remodeling of the aortic neck with a balloon-expandable stent graft in patients with complicated neck morphology

Graft migration and other device-related problems are more frequent in abdominal aortic aneurysm (AAA) patients with a complicated neck. We wanted to evaluate the performance of a balloon-expandable stent graft in these cases. Complicated aortic neck morphology was defined as a combination of short (<15 mm) and angulated (>45 degrees) necks with or without circumferential thrombus. Severe aortic angulation was defined as less than 120 degrees. During a 24-month period, 18 consecutive patients with complicated neck anatomy were treated with the Vascular Innovations (VI)-Datascope balloon-expandable endograft. In two patients, a balloon-expandable cuff was implanted to remodel the neck prior to insertion of a bifurcated endograft (Excluder, W.L. Gore & Associates, Flagstaff, AZ). Demographic, procedural, and outcome data were collected prospectively and retrospectively analyzed. All patients had preoperative computed tomographic (CT) angiography to determine aortic neck angulation and were followed with duplex ultrasonography and CT every 3 and 6 months postoperatively to assess aortic neck and sac dilatation, as well as device migration. The VI-Datascope graft consists of an aortounifemoral polytetrafluoroethylene (PTFE) graft sutured to a proximal balloon-expandable stent. The length of the graft is 40 cm; thus, the distal end of the graft always protrudes through the ipsilateral arteriotomy and can be cut to an appropriate length for each patient. The covered portion of the graft was deployed just below the level of the lowest renal artery. The proximal bare metal stent was deployed in the suprarenal area. An endoluminal hand-sewn anastomosis was performed between the aortounifemoral limb and the distal external iliac or the common femoral arteries. An occluder device was placed in the contralateral common iliac artery to prevent retrograde perfusion of the aneurysm. A femorofemoral 8 mm Dacron graft bypass was then performed to establish flow to the contralateral extremity and pelvis. Using this approach, remodeling and straightening of angulated aortic neck morphology were achieved in all cases, including in 44% of patients with severe aortic neck angulation. The average follow-up period was 11.5 months (4-21 months). There was one early occlusion (<30 days after implantation) of the PTFE limb requiring thrombectomy and one late occlusion (6 months after implantation) requiring thrombectomy and implantation of a Viabahn stent graft (W.L. Gore & Associates). Scheduled CT scans did not show any graft migration or proximal neck dilatation. Neither neck dilatation nor endograft migration was observed with the balloon-expandable stent graft. In patients with complicated aortic neck morphology, balloon-expandable stent grafts such as the VI-Datascope graft provide more secure fixation and better long-term outcomes compared with the more commonly used self-expanding endografts.

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.

No Difference in Medium-Term Outcome Between Zenith and Talent Stent-Grafts in Endovascular Aneurysm Repair

Background Many devices are available for endovascular aneurysm repair (EVAR). Our aim was to analyze morphological effects of the Zenith and Talent systems.

Methods Patients included underwent EVAR from June 1999 to June 2005 using a Zenith or Talent stent-graft, with computed tomography follow-up. Aortic dimensions over time and clinical outcome were analyzed.

Results Twenty-nine patients with Zenith stent-grafts and 33 with Talent devices were included. Mean preoperative age was similar (75.5 ± 6.0 years vs 74.2 ± 6.7 years; P = .29). Preoperative neck length was longer in the Zenith group (29.9 ± 15.2 mm vs 25.5 ± 10.8 mm; P = .10), and stent-graft oversizing was greater in the Talent patients (20.2% ± 7.9% vs 23.0% ± 11.3%). There was proximal aortic dilatation and aneurysm sac shrinkage in each group. Complication rates were comparable, with 83% of both groups free from 10-mm migration.

Conclusion Although device designs differ, there is no difference in clinical outcome between Zenith and Talent stent-grafts. Migration rates were not influenced by suprarenal fixation.

Iliac fixation inhibits migration of both suprarenal and infrarenal aortic endografts

OBJECTIVE

To evaluate the role of iliac fixation in preventing migration of suprarenal and infrarenal aortic endografts.

METHODS

Quantitative image analysis was performed in 92 patients with infrarenal aortic aneurysms (76 men and 16 women) treated with suprarenal (n = 36) or infrarenal (n = 56) aortic endografts from 2000 to 2004. The longitudinal centerline distance from the superior mesenteric artery to the top of the stent graft was measured on preoperative, postimplantation, and 1-year three-dimensional computed tomographic scans, with movement more than 5 mm considered to be significant. Aortic diameters were measured perpendicular to the centerline axis. Proximal and distal fixation lengths were defined as the lengths of stent-graft apposition to the aortic neck and the common iliac arteries, respectively.

RESULTS

There were no significant differences in age, comorbidities, or preoperative aneurysm size (suprarenal, 6.0 cm; infrarenal, 5.7 cm) between the suprarenal and infrarenal groups. However, the suprarenal group had less favorable aortic necks with a shorter length (13 vs 25 mm; P < .0001), a larger diameter (27 vs 24 mm; P < .0001), and greater angulation (19 degrees vs 11 degrees ; P = .007) compared with the infrarenal group. The proximal aortic fixation length was greater in the suprarenal than in the infrarenal group (22 vs 16 mm; P < .0001), with the top of the device closer to the superior mesenteric artery (8 vs 21 mm; P < .0001) as a result of the 15-mm uncovered suprarenal stent. There was no difference in iliac fixation length between the suprarenal and infrarenal groups (26 vs 25 mm; P = .8). Longitudinal centerline stent graft movement at 1 year was similar in the suprarenal and infrarenal groups (4.3 +/- 4.4 mm vs 4.8 +/- 4.3 mm; P = .6). Patients with longitudinal centerline movement of more than 5 mm at 1 year or clinical evidence of migration at any time during the follow-up period comprised the respective migrator groups. Suprarenal migrators had a shorter iliac fixation length (17 vs 29 mm; P = .006) and a similar aortic fixation length (23 vs 22 mm; P > .999) compared with suprarenal nonmigrators. Infrarenal migrators had a shorter iliac fixation length (18 vs 30 mm; P < .0001) and a similar aortic fixation length (14 vs 17 mm; P = .1) compared with infrarenal nonmigrators. Nonmigrators had closer device proximity to the hypogastric arteries in both the suprarenal (7 vs 17 mm; P = .009) and infrarenal (8 vs 24 mm; P < .0001) groups. No migration occurred in either group in patients with good iliac fixation. Multivariate logistic regression analysis revealed that iliac fixation, as evidenced by iliac fixation length (P = .004) and the device to hypogastric artery distance (P = .002), was a significant independent predictor of migration, whereas suprarenal or infrarenal treatment was not a significant predictor of migration. During a clinical follow-up period of 45 +/- 22 months (range, 12-70 months), there have been no aneurysm ruptures, abdominal aortic aneurysm-related deaths, or surgical conversions in either group.

CONCLUSIONS

Distal iliac fixation is important in preventing migration of both suprarenal and infrarenal aortic endografts that have longitudinal columnar support. Secure iliac fixation minimizes the risk of migration despite suboptimal proximal aortic neck anatomy. Extension of both iliac limbs to cover the entire common iliac artery to the iliac bifurcation seems to prevent endograft migration.

Effect of challenging neck anatomy on mid-term migration rates in AneuRx endografts

OBJECTIVE

To establish the effect of challenging neck anatomy on the mid- and long-term incidence of migration with the AneuRx bifurcated device in patients treated after Food and Drug Administration approval and to identify the predictive factors for device migration.

METHODS

Prospectively maintained databases at the University of North Carolina (UNC) and Washington University (WU) were used to identify 595 patients (UNC, n = 230; WU, n = 365) who underwent endovascular repair of an infrarenal abdominal aortic aneurysm with the AneuRx bifurcated stent graft. Those patients with at least 30 months of follow-up were identified and underwent further assessment of migration (UNC, n = 25; WU, n = 59) by use of multiplanar reconstructed computed tomographic scans.

RESULTS

Eighty-four patients with a mean follow-up time of 40.3 months (range, 30-55 months) were studied. Seventy percent of the patients (n = 59) met all inclusion criteria for neck anatomy (length, angle, diameter, and quality) as defined by the revised instructions for use guidelines and are referred to as those with favorable neck anatomy (FNA). The remaining 25 patients retrospectively fell outside of the revised instructions for use guidelines and are referred to as those with unfavorable neck anatomy (UFNA). Life-table analysis for FNA patients at 2 and 4 years revealed a migration rate of 0% and 6.1%, respectively. For UFNA patients, it was 24.0% and 42.1% at 2 and 4 years, respectively (P < .0001). The overall (FNA and UFNA) migration rate was 7.1% and 17.1% at 2 and 4 years, respectively. Overall, late graft-related complications occurred in 38% of patients (FNA, 27%; UFNA, 64%; P = .003; relative risk, 1.7). There was no incidence of late rupture or open conversion. The relative risk of migration for UFNA patients was 2.5 compared with FNA patients (P = .0003). A larger neck angle and a longer initial graft to renal artery distance were predictors of migration, whereas shorter neck length approached but did not reach statistical significance.

CONCLUSIONS

Patients who have unfavorable aneurysm neck anatomy experience significantly higher migration, device-related complication, and secondary intervention rates. However, there was no incidence of open conversion, rupture, or abdominal aortic aneurysm-related death, thereby supporting the AneuRx device as a feasible alternative to open repair even in patients with challenging neck characteristics. Enhanced surveillance should be used in these high-risk patients.

Beyond the aortic bifurcation: Branched endovascular grafts for thoracoabdominal and aortoiliac aneurysms

OBJECTIVES

To evaluate the use of novel technology to treat complex aortic aneurysms involving branches that provide critical end-organ blood supply.

METHODS

A prospective study was conducted in patients with thoracoabdominal, suprarenal, or common iliac aneurysms (TAA, SRA, or CIA) at high risk for open surgical repair. An endovascular graft using the Zenith platform was customized to fit patient anatomy (TAA or SRA) and combined with Jomed balloon-expandable stent-grafts. Prefabricated hypogastric branches were used with a Zenith abdominal aortic aneurysm (AAA) or Fluency self-expanding fenestrated device in conjunction with a self-expanding stent-graft. Analyses were conducted in accordance with the endovascular aneurysm reporting standards document. Follow-up studies occurred at discharge, 1, 6, and 12 months, and included computed tomography and duplex ultrasound scans, and flat plate radiography.

RESULTS

Fifty patients were treated (9 TAA, 20 SRA, 21 CIA). The mean aneurysm size was 7.6 cm (TAA), 7.2 cm (SRA), and 6.1 cm AAA size associated with a mean CIA size of 3.8 cm. Bilateral CIA aneurysms were present in 86% (18/21) of patients with CIA aneurysms. Perioperative mortality was 2% (1/50) and resulted from a myocardial infarction after a planned conduit and iliac endarterectomy required for device access. Five late deaths occurred (2 TAA, 2 SRA, 1 CIA), three of which (2 TAA, 1 SRA) were aneurysm related. Failure to access internal iliac arteries occurred in three cases, and two late hypogastric branch thromboses occurred. No visceral branches were lost acutely or occluded during follow-up. Sac shrinkage (>5 mm) was noted in 65% of patients at 6 months and in all patients (10/10) by 12 months. There were no ruptures or conversions, but nine patients required secondary interventions.

CONCLUSIONS

Branch vessel technology has made it technically feasible to preserve critical end-organ perfusion in the setting of CIA, SRA, and TAA aneurysms. The relatively low acute mortality rate and lack of short-term branch vessel loss are encouraging and merit further investigation. These advances have the potential to markedly diminish the complications associated with conventional management of complex aneurysms.

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

BACKGROUND

The development of newer-generation endografts for the endovascular treatment of abdominal aortic aneurysms has resulted in considerable improvements in clinical performance. However, long-term outcome data are still scarce. To assess long-term clinical and radiographic outcomes after use of the Talent stent graft, a retrospective analysis was performed that was based on 165 patients treated with this endograft in Germany between October 1996 and December 1998.

METHODS

Data were collected according to the recommendation of the ad hoc committee for standardized reporting practices in vascular surgery and were evaluated statistically by using univariate and multivariate analyses.

RESULTS

A total of 165 patients were treated with a Talent endograft in 9 German centers before December 31, 1998. Most were asymptomatic (94.5%), male (97.6%), and treated with a bifurcated graft (86.7%). Two patients (1.2%) died within 30 days, and 28 (17%) died during the follow-up period. The cause of death was aneurysm rupture in one case. Survival was 95.4% +/- 1.7% at 1 year, 89% +/- 2.6% at 2 years, 78.1% +/- 3.6% at 5 years, and 76.2% +/- 4.1% at 7 years. Patients classified as American Society of Anesthesiologists grade IV had a significantly lower survival rate (24.9%) than those classified as American Society of Anesthesiologists grade II and III (91.9% and 77.3%). During a mean follow-up period of 53.2 +/- 20.1 months (range, 1-84 months), 47 secondary procedures were performed in 31 patients (18.8%). Kaplan-Meier estimates showed a freedom from secondary intervention of 94.7% +/- 1.8%, 81.7% +/- 3.3%, and 77.4% +/- 3.6% at 1, 3, and 7 years, respectively. The reason for secondary treatment was endograft thrombosis in 10 patients (6.1%), persisting primary endoleak in 9 (5.5%), late secondary endoleak in 6 (3.6%), graft migration in 3 (1.8%), aneurysm rupture in 2 (1.2%), and graft infection in 1 (0.6%). Device migration (> or =10 mm) occurred in seven patients (4.2%). Other graft changes, such as graft kinking (n = 4; 2.4%), fracture of metallic stents (n = 2; 1.2%), erosion of the longitudinal bar (n = 2; 1.2%), or modular component separation (n = 1; 0.6%), were rare. Follow-up computed tomographic imaging revealed a decrease of the maximum aneurysm sac diameter (>5 mm) in 106 (64.2%) patients and an increase in 14 (8.5%) patients. The mean aneurysm diameter significantly decreased (P < .001). Of the factors recorded at baseline, only endoleaks showed a significant correlation with the risk of aneurysm increase during follow-up (P < .001). Adverse anatomy (neck diameter >28 mm, neck length <15 mm, and '5 patent aortic branches) did not adversely influence the aneurysm shrinkage rate, the risk for a secondary procedure, or the clinical success rate. A significantly higher rate of clinical success (P < .05) was observed in patients older than 65 years of age.

CONCLUSIONS

Implantation of the Talent endograft device is a safe and effective alternative to open surgery for exclusion of abdominal aortic aneurysm. In comparison with first-generation grafts, the device showed superior durability for as long as 5 to 7 years after implantation. Even if prototypes of the Talent device were implanted in this study, the graft was also successfully used in most patients, even in those with adverse anatomy. Because improvements of the endograft have been made to address connecting bar breaks, a lower incidence of graft limb occlusion can be expected in the future.

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

BACKGROUND

Freedom from migration is key to the durability of endovascular aneurysm repair (EVAR). This study evaluates the mid- and long-term incidence of migration with two different endografts.

METHODS

Between September 1997 and June 2004, 235 patients were scheduled for EVAR with an AneuRx (Medtronic/AVE Inc.) or Zenith (Cook) endograft. Patients with fusiform, infrarenal aneurysms and a minimum 12 months of follow-up were analyzed, for a final cohort of 130 patients. Migration was assessed on axial computed tomography (CT) (2.5 to 3 mm cuts) as the distance from the most caudal renal artery to the first slice containing endograft (AneuRx) or to the top of the bare suprarenal stent (Zenith). Aortic neck diameters were measured at the most caudal renal artery. The initial postoperative CT scan was the baseline. Migration was defined by caudal movement of the endograft at two thresholds, > or =5 mm and > or =10 mm, or any migration with a related clinical event.

RESULTS

Life-table analysis demonstrated AneuRx freedom from migration (> or =10 mm or clinical event) was 96.1%, 89.5%, 78.0%, and 72.0% at 1, 2, 3, and 4 years, respectively. Zenith freedom from migration was 100%, 97.6%, 97.6%, and 97.6% at 1, 2, 3, and 4 years, respectively (P = .01, log-rank test). The stricter 5-mm migration threshold found 67.4% of AneuRx and 90.1% of Zenith patients free from migration at 4 years of follow-up. Twelve out of 14 (85.7%) AneuRx patients (12/14) with migration (> or =10 mm or clinical event) underwent 14 related secondary procedures (13 endovascular, 1 open conversion). The single Zenith patient with migration (> or =10 mm) has not required adjuvant treatment. Mean follow-up was 39.0 +/- 2.3 months (AneuRx) and 30.8 +/- 1.9 months (Zenith, P = .01). Patients with and without migration did not differ in age, gender ratio, aneurysm diameter, and neck diameter. However, initial neck length was shorter in patients with migration (22.1 +/- 2.1 mm vs 31.2 +/- 1.2 mm, P = .02). A subset of patients (21.6%) experienced significant (defined as > or =3 mm) maximum aortic neck dilation. Of the AneuRx patients, > or =3 mm aortic neck dilation affected 30.8% of migrators vs 13.0% of nonmigrators (P = .20).

CONCLUSIONS

Endograft migration is a time-dependent phenomenon affected by both device choice and aortic neck length. A great majority of patients (85.7%) with migration of the AneuRx device ultimately required treatment. A minority of patients experienced aortic neck dilation that could be considered clinically significant. Careful surveillance for migration is an essential component of long-term follow-up after EVAR.

Decreased use of iliac extensions and reduced graft junctions with software-assisted centerline measurements in selection of endograft components for endovascular aneurysm repair

OBJECTIVE

The purpose of this study was to determine the impact of using computerized software-assisted centerline measurements for extensions and graft junctions during the selection of endograft components for modular aortic endografts in endovascular repair of abdominal aortic aneurysms.

METHODS

From April 1998 to December 2002, 289 modular aortic endografts were implanted at our institution. These included 248 grafts (prior to 2002, group 1) with components selected on the basis of manual caliper measurements from combined contrast computed tomography (CT) and marker-catheter arteriography data, and 41 grafts (2002, group 2) with components selected with the use of computerized software that allowed for centerline measurements on 3-dimensional reconstructions based on CT data. These 2 groups were compared for the number and type of extensions required per case. Seventeen other relevant variables were analyzed for their potential influence on selection of endograft components. These variables included age, gender, maximum aneurysm size, level of distal fixation, length and diameter at the fixation points, endograft manufacturer (make), and configuration. The significance of the observed differences was analyzed with a multivariate regression model, adjusting for potentially confounding preoperative measures.

RESULTS

Multivariate analysis demonstrated that the number of right iliac extensions, left iliac extensions, total extensions, and total graft junctions was significantly reduced by the use of computerized software-assisted centerline measurements (group 2) compared with caliper measurements (group 1), independent of all other 17 preoperative variables. Notably, the mean number of required right iliac extensions was double in group 1 versus group 2.

CONCLUSIONS

Centerline software-assisted measurements can significantly reduce the need for iliac extensions and, concomitantly, the number of required endograft junctions. On average, twice as many extensions were required for right iliac fixation when the manual caliper measurements were used compared with software-assisted measurements. These findings are highly relevant to issues of total endograft cost and long-term endograft integrity and focus attention on the tools that may need to be considered standards of care rather than optional for selection of endograft components.

Endovascular management of juxtarenal aneurysms with fenestrated endovascular grafting

PURPOSE

To evaluate the technical feasibility and short-term results of juxtarenal aneurysm repair with an endovascular graft that incorporated the visceral aortic segment with graft material.

METHODS

Patients were studied prospectively after the implantation of an endovascular device with graft material extending proximal to the renal arteries, variably incorporating the superior mesenteric and celiac arteries. All patients were deemed to be high risk with respect to open surgical repair and had compromised proximal neck anatomy. Proximal neck lengths were <or=10 mm, or <or=15 mm with a challenging morphology (funnel shape or extensive thrombus). Fenestrations within the graft material were customized to accommodate visceral and renal vessels on the basis of computerized tomography (CT), angiography, or intravascular ultrasound data. Selected visceral ostia were protected with balloon-expandable stents after partial endograft deployment. All patients were evaluated with CT and kidney, ureters, and bladder x-ray at discharge and at 1, 6, and 12 months. Visceral duplex scan studies were performed at 1, 6, and 12 months.

RESULTS

A total of 22 patients were enrolled in the study. Sixteen patients had short proximal necks (3-10 mm), and six had compromised necks of 10 to 15 mm in length. Endograft design included bifurcated (20) and tube (2) systems. All prostheses were implanted successfully without the acute loss of any visceral arteries. A total of 58 visceral vessels were incorporated (mean, 2.6 per patient) and most commonly included both renal arteries and the superior mesenteric artery. The mean follow-up was 6 months. There were no deaths within 30 days and no aneurysm-related deaths during the follow-up period. Two early (<30 days) and two late secondary interventions were performed, inclusive of two visceral artery stenoses detected with duplex scanning. The 30-day endoleak rate was 4.5%. The aneurysm sac decreased greater than 5 mm in 53 % of patients at 6 months and three of four patients at 12 months. Three patients developed renal insufficiency, only one of which required temporary hemodialysis.

CONCLUSIONS

The placement of an endovascular prosthesis with graft material that incorporates the visceral arteries is technically feasible. The occurrence of endoleaks appears to be relatively low. The increased sealing and fixation zones in this patient population should limit the late development of proximal endoleak or migration; however, this situation will require more patients and extended follow-up.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Volume regression of abdominal aortic aneurysms and its relation to successful endoluminal exclusion

OBJECTIVES

Evaluating the success of endoluminal repair of abdominal aortic aneurysms (AAAs) is frequently based on diameter measurements and determining the presence of endoleaks. The use of three-dimensional volumetric data and observation of morphologic changes in the aneurysm and device have been proposed to be more appropriate for postdeployment surveillance. The purpose of this study was to analyze the long-term volumetric and morphologic data of 161 patients who underwent endovascular AAA exclusion and to assess the utility of volume measurements for determining successful AAA repair.

METHODS

Patients with spiral computed tomography scans obtained preoperatively, within the first postoperative month, at 6 months, and annually thereafter, were included in this analysis. Computerized interactive three-dimensional reconstruction of each AAA scan was performed. Total aneurysm sac volume was measured at each time interval (mean preoperative volume 169.0 +/- 78.5 mL), and the significance of volume changes was determined by mixed linear modeling, a form of repeated measures analysis, to account for longitudinal data clustered at the individual level. Sixty-two patients (38%) developed endoleaks at some time during follow-up-15 type I leaks, 45 type II leaks, and 2 type III leaks. The patients with type I and type III leaks were treated with cuffs, and the type II leaks were treated either with observation, side-branch embolization, or required open conversion.

RESULTS

Aneurysm sac volume increased slightly at 1-month follow-up (+3.3%), and then decreased steadily to -12.9% at 5 years (P <.0001). This effect remained unchanged after controlling for the three device types used in our study population. Patients who did not exhibit an endoleak (n = 99) showed a significant decrease in aneurysm volume across the entire follow-up duration when compared with those who did exhibit an endoleak (n = 62) (P <.0001). The presence of a 10% or greater decrease in volume at 6 months demonstrated a sensitivity of 64%, a specificity of 95%, a positive predictive value of 95%, a negative predictive value of 62%, and an accuracy of 75% for predicting primary clinical success defined by successful deployment of the device; freedom from aneurysm- or procedure-related death; freedom from endoleak, rupture, migration, or device malfunction; or conversion to open repair.

CONCLUSIONS

Volumetric analysis may be used to predict successful endoluminal exclusion of AAAs. Volume regression appears to be device-independent and should be expected in most clinically successful cases. The presence of volume increases in the first 6 months is suspicious for an endoleak that is pressurizing the aneurysm sac and heralds the need for closer evaluation and possible intervention. A volume decrease of 10% or greater at 6 months and continuing regression over time is associated with successful endovascular repair.

Factors Affecting the Displacement Force Exerted on a Stent Graft after AAA Repair—An In vitro Study

OBJECTIVES

To investigate the distraction forces affecting grafts used to treat abdominal aortic aneurysms in an in vitro model.

METHOD

Using a standard cardiac pump and a rigid plastic circulation system, distraction forces were measured with a gramometer attached to a PTFE graft while the pressure inside a rigid aortic sac was varied.

RESULTS

If the pressure in the 'aneurysm sac' is maintained at the same level as the systemic pressure, the displacement force is zero. The displacement force is affected adversely by the level of systemic pressure, as this rises the displacement forces rise in an almost linear fashion.

CONCLUSIONS

These observations may have important consequences for stent graft design and use in vivo pressurisation of a sealed sac may therefore not necessarily be an adverse event. Systemic hypertension is obviously important and its control may be necessary to prevent graft migration.

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

OBJECTIVE

We reviewed the incidence of stent-graft migration after endovascular aneurysm repair in a prospective multicenter trial and identified factors that may predispose to such migration.

METHODS

All patients who received treatment during the course of the multicenter AneuRx clinical trial were reviewed for evidence of stent-graft migration over 5 years, from 1996 to 2001. Post-deployment distance from the renal arteries to the proximal end of the stent graft and the proximal fixation length (length of the infrarenal neck covered by the stent graft) were determined in patients for whom pre-procedure and post-procedure computed tomography scans were measured in an independent core laboratory.

RESULTS

Stent-graft migration was reported in 94 of 1119 patients, with mean time after device implantation of 30 +/- 11 months. Freedom from migration was 98.6% at 1 year, 93.4% at 2 years, and 81.2% at 3 years (Kaplan-Meier method). Subset (n = 387) analysis revealed that initial device deployment was lower in 47 patients with migration, as evidenced by a greater renal artery to stent-graft distance (1.1 +/- 0.7 cm), compared with 340 patients without migration (0.8 +/- 0.6 cm; P =.006) on post-implantation computed tomography scan. Proximal fixation length was shorter in patients with migration (1.6 +/- 1.4 cm) compared with patients without migration (2.3 +/- 1.4 cm; P =.005). There was significant variation in migration rate among clinical sites (P <.001), ranging from 0% to 30% (median, 8%), with a greater than twofold difference in migration rate between the lowest quartile (6%) and the highest quartile (15%) clinical sites. Univariate and multivariate analysis revealed that renal artery to stent-graft distance (P =.001) and proximal fixation length (P =.005) were significant predictors of migration, and that each millimeter increase in distance below the renal arteries increased risk for subsequent migration by 5.8% and each millimeter increase in proximal fixation length decreased risk for migration by 2.5%. Pre-implantation aortic neck length, neck diameter, degree of device oversizing, correct versus incorrect oversizing, device type (stiff vs flexible), placement of proximal extender cuffs at the original procedure, and post-procedure endoleak were not significant predictors of migration. Migration was treated with placement of extender modules in 23 patients and surgical conversion in 7 patients; 64 patients (68%) with migration have required no treatment.

CONCLUSIONS

Stent-graft migration among patients treated in the AneuRx clinical trial appears to be largely related to low initial deployment of the device, below the renal arteries, and short proximal fixation length. Significant variation in migration rate among clinical sites highlights the importance of the technical aspects of stent-graft deployment. Advances in intraoperative imaging and deployment techniques that have been made since completion of the clinical trial facilitate precision of device placement below the renal arteries and should increase proximal fixation length. Whether this, together with increased iliac fixation length, will result in lower risk for migration remains to be determined in long-term follow-up studies.

Impact of an endovascular program on the operative experience of abdominal aortic aneurysm in vascular fellowship and general surgery residency

BACKGROUND

This study was performed to determine the impact of an endovascular program (EVP) on open and endovascular abdominal aortic aneurysm (AAA) operations in a residency training institution.

METHODS

Over an 8-year period ending in September 2001, hospital records of all patients undergoing open or endovascular AAA repair were retrospectively reviewed. Data were analyzed to determine the changing patterns of case volume, type of operative repair, and complexity of open repair with regards to the training of both general surgical chief residents and vascular fellows.

RESULTS

A total of 849 AAA operations were performed during the study period. The initiation of the EVP in 1997 resulted in a steady increase in the total annual AAA cases (P < 0.05), due in part to an increase in endovascular AAA operations despite a decrease in the annual open AAA volume. EVP had a positive impact on the overall operative experience of vascular fellows owing to the large increase in their endovascular AAA experience (annual mean pre-EVP 3 +/- 0.8 versus post-EVP 47 +/- 9.6, P < 0.01). A significant reduction occurred in the vascular fellows' open AAA experience (annual mean pre-EVP 40 +/- 12.7 versus post-EVP 19 +/- 9.4, P < 0.05). EVP did not affect the endovascular AAA experience of general surgery chief residents (annual mean pre-EVP 1 +/- 0.8 versus post-EVP 3 +/- 1.5, not significant). A significant reduction occurred in chief residents' open AAA experience (annual mean pre-EVP 39 +/- 9.7 versus post-EVP 18 +/- 7.4, P < 0.05). EVP did not affect the operative experience of complex open AAA operations in either vascular fellows or general surgery residents.

CONCLUSIONS

An endovascular program has a positive impact on the aortic aneurysm practice in an academic institution, as evidenced by the significant increase in annual endovascular AAA cases despite a decrease in open AAA operations. Although vascular fellows continued to maintain sufficient experience in both open and endovascular AAA operations, general surgery chief residents suffered a significant decrease in their open AAA experience. Further evaluation of the residency system is warranted to better optimize the training paradigm of both vascular fellowship and general surgery residency.