Abdominal Aortic Aneurysm Exclusion Research Articles

Long-term fate of the aneurysmal sac after endoluminal exclusion of abdominal aortic aneurysms

Purpose: Shrinkage of an abdominal aortic aneurysm (AAA) is the hallmark of successful endoluminal treatment. Our goal was to prospectively assess the midterm to long-term shrinkage of the AAA sac after endovascular repair. Methods: A total of 123 patients with AAA underwent endoluminal treatment with the Ancure device at our institution between February 1996 and February 2000. At least a 1-year follow-up was available for 70 of the 123 patients. AAA sac size, presence of endoleaks, calcifications, and outcome data were collected on these patients at 6, 12, 24, and 36 months after repair and compared with the preoperative AAA size and characteristics. All endoleaks found at the 6-month follow-up visit were treated aggressively with embolotherapy. An AAA sac regression of 0.5 cm or more was considered the minimum measurable decrease. Regression of the sac diameter to 3.5 cm or less was considered a complete collapse of the sac. Results: Successful endoluminal repair was accomplished in 119 of 123 patients. The mortality rate was 0.8% (1/123). There was a steady decrease in AAA sac size from baseline (5.56 ± 0.1 cm), to 6 months (5.0 ± 0.14 cm, P =.0006), to 12 months (4.65 ± 0.13 cm, P =.04), and to 24 months (4.26 ± 0.16 cm, P =.03). At 24 months, 74% (29/39) had a decrease in sac size of 0.5 cm or more, with 28% (11/39) complete collapse. Patients with initial endoleaks had the same likelihood of regression of sac size (≥ 0.5 cm) when compared with the group of patients with no endoleaks at the 24-month evaluation (64% vs 76%, P =.09). Conclusion: Endoluminal AAA repair resulted in a significant reduction in sac size that continues up to 2 years. Significant shrinkage occurs as early as 6 months after placement. The initial presence of endoleaks does not predict the lack of sac regression.(J Vasc Surg 2000;32:689-96.)

Aortic Stent-Grafting With Transrenal Fixation: Use of Newly Designed Spiral Z-Stent Endograft

Purpose:To evaluate the feasibility and efficacy of a newly designed stent-graft placed across the renal arteries for exclusion of abdominal aortic aneurysms (AAAs) with short or tortuous proximal ...

Late abdominal aortic aneurysm rupture after AneuRx repair: A report of three cases

Rupture due to device failure and/or endoleak is the most feared complication of endoluminal grafting for exclusion of abdominal aortic aneurysm. We present three previously unreported cases of abdominal aortic aneurysm rupture 23 months after AneuRx “repair” and describe the mechanisms of failure and discuss instructive technical aspects of their management.

Late abdominal aortic aneurysm rupture after AneuRx repair: A report of three cases

Rupture due to device failure and/or endoleak is the most feared complication of endoluminal grafting for exclusion of abdominal aortic aneurysm. We present three previously unreported cases of abdominal aortic aneurysm rupture 23 months after AneuRx "repair" and describe the mechanisms of failure and discuss instructive technical aspects of their management.

Anatomical importance of infrarenal aortic branches in conventional and endovascular surgery: a review.

Minimally invasive or catheter-directed, endoluminal stent-graft treatment of abdominal aortic aneurysms (AAA) is a novel and important advance in the armamentarium of the vascular surgeon and interventional therapist. Provided adequate training is available, infrastructure is optimal, and patient selection correct, successful exclusion of AAA can safely and effectively be achieved with low morbidity and mortality by this lesser invasive technique. An important Achilles heel of endovascular repair (EVR) of AAA is back bleeding or endoleak formation due to incomplete sealing or bridging of aortic branches ostia by endoluminal stents. Significant, recurrent, and persistent retroleaks, a topic of clinical interest, are related to either incompletely sealed-off inferior mesenteric and/or lumbar arteries. The optimal method to diagnose and manage these endoleaks is currently in a state of evolution. In the process of stent-graft treatment of AAA, other important aortic branches are also bridged that may potentially present with the sequelae of peripheral ischemia. This review re-emphasizes the anatomical and clinical importance of abdominal aortic branches relevant to conventional aortic surgery and EVR of AAA.

The incidence, natural history, and outcome of secondary intervention for persistent collateral flow in the excluded abdominal aortic aneurysm

Objective: The goal of abdominal aortic aneurysm (AAA) repair is the prevention of rupture. Exclusion of the infrarenal AAA by means of operation or endovascular graft placement is an alternative therapy to achieve this goal. However, thrombosis of the excluded aneurysm sac does not always occur and further intervention may be needed. This study examines the efficacy of available screening methods to detect the persistence of aneurysm sac flow and the outcome of secondary procedures to treat this problem. Methods: During the past 14 years, 1218 patients have undergone operative retroperitoneal exclusion of AAA. To date, 48 patients have been found to have persistent flow in the excluded AAA sac with duplex scanning. Twenty-seven patients underwent surgical intervention, and seven of these procedures were performed for rupture. Six patients have undergone treatment with interventional techniques (four successfully). The patients were evaluated for preoperative angiographic, anatomic, and comorbid factors that may have predisposed them to failed exclusion. Also, perioperative morbidity and mortality, estimated blood loss, and survival were assessed in the patients who required surgical treatment. Results: There were no perioperative parameters that correlated with postoperative persistent flow in the excluded AAA sac. The mean time to secondary intervention was 51 months (range, 2 to 113 months). Two patients had false-negative computed tomographic angiogram results, eight patients had false-negative angiogram results, and six patients had duplex scan examinations that had initially negative results that were then positive for flow in sac. Reoperation had a 7.4% mortality rate (two deaths) and a median blood loss of 2600 mL, as compared with 500 mL for primary procedures. Conclusion: Secondary operations for patent excluded aortic aneurysm sacs have higher mortality and intraoperative blood loss rates than do primary procedures for AAA repair. The localization of branch leaks with computerized tomographic angiography, angiography, and duplex scanning were imprecise, and better methods are needed to adequately diagnose patent sacs. Expansion of AAA sac may be the only reliable factor. (J Vasc Surg 1999;30:968-76.)

Length Measurements of the Aorta After Endovascular Abdominal Aortic Aneurysm Repair

Background successful endovascular repair of abdominal aortic aneurysms (AAA) generally leads to a decrease in aneurysm size. Theoretically, this may lead to foreshortening of the excluded segment. If so, vertically rigid endografts may dislocate over time and cover renal or hypogastric arteries. Aim to assess length changes of the infrarenal aorta after endovascular AAA exclusion. Patients and methods forty-four consecutive patients were scheduled for the EndoVascular TechnologiesÒendograft, a vertically non-rigid prosthesis which would potentially accommodate longitudinal changes. Twenty-four patients had completed at least 6 months of follow-up. In 18/24 patients a decrease in size was established by aneurysm volume measurements at 6 months» follow-up. Helical computer tomography (CT) angiograms were processed on a workstation. Aortic lengths were measured along the central lumen line from the lower renal artery orifice to the native aortic bifurcation. The computer tomography angiogram (CTA) reconstruction thickness of 2 mm yields at least a 4-mm error for each length measurement. Results in the shrinking aneurysm group, the median length change was 0 mm (range −9 mm to +4 mm) at 6 months» follow-up (n =18) and also 0 mm (range −7 mm to +4 mm) at 12 months» follow-up ( n =10). In 16/18 patients, length changes remained within the measurement error range of 4 mm. Conclusion in this group of shrinking aneurysms after endovascular AAA repair, foreshortening of the excluded aortic segment appears not to be a clinically significant problem.

Endovascular Repair of Abdominal Aortic Aneurysm Using a Pararenal Fenestrated Stent-Graft

To report an unusual case of endovascular abdominal aortic aneurysm (AAA) exclusion in which a fenestrated stent-graft was used to seal a proximal Type I endoleak. An 84-year-old man with a 6.0-cm AAA underwent an aortomonoiliac aneurysm exclusion procedure that was complicated by a proximal endoleak. Because the patient had no right kidney, an additional stent-graft was designed to cover the right renal artery stump while preserving left renal perfusion through a fenestration in the graft material. This approach was successful in obliterating the endoleak around the proximal attachment site, but flow through the lumbar arteries remained. The use of a fenestrated stent-graft is feasible, but the type of fenestration in this case has limited applicability owing to the rarity of patients with suitable anatomy.

Endotension: An Explanation for Continued AAA Growth after Successful Endoluminal Repair

Purpose: To present and analyze several cases that illustrate persistent sac pressurization following endovascular abdominal aortic aneurysm (AAA) repair. Methods and Results: Four patients with successful endovascular AAA exclusion presented in follow-up with an expanding aneurysm. Two had initial sac diameter decrease, but by 18 and 24 months, respectively, the AAA had enlarged and become pulsatile. There was no endoleak evident, but the proximal attachment stents had migrated distally in both cases. One patient developed endoleak with aneurysm expansion at 6 months; contained rupture occurred at 12 months. The last case had slowly evolving aneurysm expansion over 36 months but no endoleak. All endografts were removed and successfully replaced with conventional grafts. Intrasac thrombus was implicated as the means of pressure transmission that precipitated AAA expansion in these cases. Conclusions: Excluded AAAs can increase in size owing to persistent or recurrent pressurization (endotension) of the sac even when there is no evidence of endoleak. One proposed mechanism is pressure transmission via thrombus that lines the attachment site. Endotension may also represent an indiscernible, very low flow endoleak that allows blood to clot at the source of leakage.

Endotension: An Explanation for Continued AAA Growth After Successful Endoluminal Repair

To present and analyze several cases that illustrate persistent sac pressurization following endovascular abdominal aortic aneurysm (AAA) repair. Four patients with successful endovascular AAA exclusion presented in follow-up with an expanding aneurysm. Two had initial sac diameter decrease, but by 18 and 24 months, respectively, the AAA had enlarged and become pulsatile. There was no endoleak evident, but the proximal attachment stents had mig rated distally in both cases. One patient developed endoleak with aneurysm expansion at 6 months; contained rupture occurred at 12 months. The last case had slowly evolving aneurysm expansion over 36 months but no endoleak. All endografts were removed and successfully replaced with conventional grafts. Intrasac thrombus was implicated as the means of pressure transmission that precipitated AAA expansion in these cases. Excluded AAAs can increase in size owing to persistent or recurrent pressurization (endotension) of the sac even when there is no evidence of endoleak. One proposed mechanism is pressure transmission via thrombus that lines the attachment site. Endotension may also represent an indiscernible, very low flow endoleak that allows blood to clot at the source of leakage.

Treatment of abdominal aortic aneurysms with the talent stent-graft system: Techniques and problem solving

The Talent bifurcated stent-graft system is a modular-type endoluminal prosthesis designed for exclusion of abdominal aortic aneurysm. Unique features include a bare proximal spring for transrenal fixation and the manufacturer's customization to fit a wide range of sizes and morphologies. Success of endoluminal exclusion is largely dependent on precise preoperative measurements and stent-graft design, as well as technical execution of the implant, including troubleshooting and problem solving. The most common challenges relate to morphology and/or short length of the proximal neck, and anatomy and/or small size of the access iliac arteries. Useful technical alternatives and troubleshooting maneuvers have evolved that are likely to maximize success and decrease complications. Overall, the Talent aortic endograft performs very satisfactorily. The newly designed low profile system is likely to increase applicability and technical success through a reduction in the profile of the delivery sheath.

Special iliac artery considerations during aneurysm endografting

Background: The feasibility of endograft exclusion of abdominal aortic aneurysms (AAA) has been established. However, the technical challenges of graft delivery through tortuous or diseased iliac arteries and the treatment of associated iliac aneurysmal disease have received little attention. Methods: Over 19 months, 74 patients underwent endoluminal repair of AAA and/or iliac artery aneurysms. Iliac anatomy that required special consideration during endografting was reviewed. Results: Of the 74 patients, 35 (47%) had iliac anatomy that required special attention. Thirteen patients (18%) had aneurysmal involvement of a common iliac artery. Eleven of these patients required endograft extension into the external iliac artery (EIA) and hypogastric coil embolization due to the proximity of the aneurysm to the hypogastric origin. Eleven patients with ectatic, nonaneurysmal iliac arteries required aortic cuffs to achieve a distal seal in these oversized vessels. Iliac artery tortuosity or stenosis were complicating factors in 27 of the 74 patients (36%), requiring the use of brachial guidewire tension in 2 patients to facilitate tracking of the delivery device. Five patients with severely splayed aortic bifurcations required crossed placement of the iliac limbs to prevent kinking of the endograft. Occlusive atherosclerotic disease of the EIA mandated preprocedural dilatation and stenting in 3 patients and postprocedural surgical EIA reconstruction in another 5 patients. Three patients who underwent successful endograft placement required subsequent endovascular repair of traumatized EIAs. Conclusions: Iliac artery anatomy plays a significant role in the endoluminal treatment of infrarenal abdominal aortic aneurysms, complicating the procedure in up to 47% of patients with otherwise suitable anatomy. A variety of supplemental procedures, both surgical and endovascular, may be required to facilitate endograft placement. A special understanding of these constraints and proper planning is required for optimal therapy.

Complications in the Endovascular Repair of Abdominal Aortic Aneurysms: a Risk Factor Analysis

Objectives: to identify risk factors for complications following endovascular repair of abdominal aortic aneurysms (AAAs). Materials and methods: endovascular AAA exclusion was attempted in 64 patients. Patient characteristics, anatomic features of the aneurysm, operative technical aspects, and the experience of the teams were correlated with mortality, occurrence of endoleak, and other complications. Perioperative complications were graded following the recommendations of the Ad Hoc Committee on reporting standards. For the assessment of correlation between risk factors and outcomes a logistic regression analysis was used. Results: complications were observed in 43% of the procedures and were classified as mild (24%), moderate (55%) or severe (21%). American Society of Anaesthesiology (ASA) risk class 3 or 4, and advanced age were independent risk factors for perioperative death and complications. Adjuvant procedures or overstenting of the renal arteries with the uncovered part of the stent were not associated with increased risk of complications. Nevertheless, in four of 24 overstented renal orifices, a renal infarction or ischaemia of the kidney was observed on a postoperative CT scan. Advanced experience was associated with less complications, less endoleaks, and shorter operating time.Conclusions: high age and medical co-morbidity were associated with increased risk for perioperative complications and death. Additional perioperative procedures are usually well tolerated. With greater experience in endovascular AAA grafting the incidence of complications and endoleaks decreased.

Histology and Electron Microscopy of Explanted Bifurcated Endovascular Aortic Grafts: Evidence of Early Incorporation and Healing

To report an examination of explanted bifurcated endovascular aortic grafts for histologic evidence of early healing and incorporation. Two bifurcated endovascular aortic grafts composed of polycarbonate urethane and Elgiloy wire were explanted 42 and 21 days after successful endovascular exclusion of abdominal aortic aneurysms. Both patients expired from causes unrelated to endograft deployment. The explanted devices were examined using immunohistochemical analysis and electron microscopy. On explantation, both grafts appeared to have excluded the aneurysm with no evidence of endoleak, graft migration, or thrombosis. Histological examination showed numerous inflammatory cells and good ingrowth of tissue into the proximal 2 cm of the graft. Collagen and smooth muscle cells were evident in the proximal portion of the graft with only collagen in the distal segments. Neointimal formation was seen within the proximal 2 cm also, but not at the distal segments. Macrophages were present in the graft. Scanning electron microscopy showed an extensive matrix of fibers that most likely represented collagen. Bifurcated endovascular aortic grafts show inflammatory and mild foreign body reactions, collagen formation, and intimal ingrowth during healing. These findings are similar to some of the healing properties reported for sutured grafts, as well as other endovascular grafts.

Polytetrafluoroethylene-encapsulated Stent-Grafts: Use in Experimental Abdominal Aortic Aneurysm

To evaluate expanded polytetrafluoroethylene (ePTFE) encapsulated stents for the treatment of aortic aneurysms with emphasis on the blood and tissue-material interactions. Experimental aortic aneurysms were created in dogs by enlarging the aortic lumen with an abdominal fascial patch. Twenty animals underwent endoluminal repair after allowing the surgically created aneurysm to heal for 2 months prior to transluminal aneurysmal exclusion. The device used consisted of an 8-cm-long ePTFE encapsulated stent graft. The animals were killed in groups at 1 week and at 1, 2.25, 6, and 12 months. Specimens were processed for histologic and luminal surface studies. Before the animals were killed, aortography demonstrated two thrombosed aortae in the 6-month group and two endoleaks in the 12-month group. Endothelialized neointima extended into the proximal and distal portions of the prosthetic lumen, with minimal cell coverage in the center of the graft. The overall percent surface area covered by endothelialized neointima was 22% +/- 6% at 6 months and 18% +/- 10% by 1 year (P = .75). Histologic examination demonstrated minimal tissue penetration into the ePTFE. Transluminal exclusion of abdominal aortic aneurysms by encapsulated stent-graft is easily accomplished. With this device, tissue coverage and penetration of the stent graft is limited and does not tend to increase with time.

AneuRx stent graft versus open surgical repair of abdominal aortic aneurysms: Multicenter prospective clinical trial

The results of a prospective, nonrandomized, multicenter clinical trial that compared endovascular stent graft exclusion of abdominal aortic aneurysms with open surgical repair are presented. During an 18-month period, 250 patients with infrarenal aneurysms underwent treatment at 12 study sites—190 patients underwent endovascular repair using the Medtronic AneuRx stent graft (Sunnyvale, Calif), and 60 underwent open surgical repair. There was no significant difference in operative mortality rates between the groups. The patients who underwent stent grafting had significant reductions in blood loss, time to extubation, and days in the intensive care unit and in the hospital, with an earlier return to function. The major morbidity rate was reduced from 23% in the surgery group to 12% ( P < .05) in the stent graft group. There was no difference in the combined morbidity/mortality rates between the two groups. Primary technical success at the time of discharge for the patients with stent grafts was 77%, largely as a result of a 21% endoleak rate. At 1 month, the endoleak rate had decreased to 9%. There was no difference in the primary or secondary procedure success rates at 30 days between the surgery and stent graft groups. The primary graft patency rate at 6 months was 98% in the surgery group and 97% in the stent graft group. The aneurysm exclusion rate at 1 month and 6 months was 100% in patients who underwent surgery and 91% in patients who underwent stent grafting. Stent graft migration occurred in three patients and resulted in late endoleaks; each endoleak was corrected by means of endovascular placement of a stent graft extender cuff. There have been no aneurysm ruptures and no surgical conversions to open repair in the stent graft group. Stent graft repair compares favorably with open surgical repair, with a reduced morbidity rate, shortened hospital stays, and satisfactory short term outcomes. (J Vasc Surg 1999;29:292-308.)

Stents for the Treatment of Aortic Aneurysms

The endovascular treatment of abdominal aortic aneurysms has generated a great deal of interest since the early 1990s, and many different devices are currently available. The procedure of endovascular repair has been evaluated in many institutions and the different devices are compared. The first results were encouraging, but complications like endoleak, dislocation or thrombosis of the graft occurred. By the available devices the stent application is only promising, if the known exclusion criteria are strictly respected. Therefore a careful preinterventional assessment of the patient by different imaging modalities is necessary. As the available results up to now are preliminary and the durability of the devices has to be controlled, multicenter studies are required to improve the devices and observe their long-term success in the exclusion of abdominal aortic aneurysms.

Dilatation of the Infrarenal Aneurysm Neck after Endovascular Exclusion of Abdominal Aortic Aneurysm

Purpose: To determine the fate of the infrarenal aneurysm neck and suprarenal aorta after endovascular exclusion of abdominal aortic aneurysms (AAAs). Methods: Thirty-four patients underwent endovascular AAA repair between January 1994 and December 1995 using custom-made stent-grafts constructed from polyester graft material and modified self-expanding Gianturco Z-stents sutured to the graft orifices. Thirty-one patients were available for follow-up. Pre- and postimplantation diameters were measured using spiral computed tomography in the infrarenal aneurysm neck and the suprarenal aorta at the level of the superior mesenteric artery (SMA). Results: The mean follow-up time was 25 months. There was a significant increase of the diameter of the infrarenal aneurysm neck (+ 1.65 mm, p = 0.002), but not in the aorta at the level of the SMA (+ 0.52 mm, p = 0.100). There was no difference in the change in diameter in the infrarenal neck in the group with a stent adjacent to the level of measurement (n = 20) compared with the group without an adjacent stent (n = 11, p = 0.790). There was no correlation between preimplantation size of the infrarenal neck and its diameter change (r = 0.14, p = 0.488). There was no correlation (r = 0.10, p = 0.603) or association (chi-square test, p = 0.211) between aortic diameter change at the level of the SMA and the infrarenal neck. Conclusions: This investigation shows a significant dilatation of the infrarenal aneurysm neck, but not in the suprarenal aorta, after endovascular AAA repair with this device. The clinical significance of these findings is unclear. Whether such a dilatation in the infrarenal aneurysm neck may affect the long-term attachment of stent-grafts remains to be shown in the future.

Experience with the Stentor Endograft at Four Italian Centers

Purpose: To report the outcome of an Italian multicenter trial of endovascular abdominal aortic aneurysm (AAA) exclusion using the Stentor device. Methods: Between April 1995 and July 1996, 66 patients (63 men; average age 69 years, range 53 to 84) with infrarenal AAAs meeting the inclusion criteria were enrolled. The average diameter of the aneurysm was 4.6 cm (range 4.2 to 7). Three (4.5%) of the 66 AAAs were anastomotic aneurysms. Results: Sixteen (25%) tubular and 50 (76%) bifurcated endograft procedures were attempted; 4 (6.1%) were converted and 1 terminated owing to technical faults with the bifurcated graft's second limb. One tube graft was too short and failed to exclude an anastomotic aneurysm. Sixty (91%) endograft procedures were completed successfully. Six (9.1%) vascular complications occurred, three in one patient who subsequently died of pulmonary embolism 72 hours postoperatively (1.5% mortality). There were four (6.1%) proximal endoleaks; two sealed spontaneously in &lt; 1 month, and a third was converted (7.6% conversion rate). The fourth is being observed. Clinical success (aneurysm exclusion with no death or endoleak) at 30 days was 86.3% (57/66). In the 23-month follow-up of 57 eligible patients, 2 patients died of unrelated causes and 1 graft limb thrombosed, requiring a crossover femoral bypass. One patient was converted to surgical repair at 5 months postoperatively when increasing aneurysm size signaled an undisclosed endoleak (1.8% late conversion rate). Five other secondary endoleaks were treated with endovascular techniques. Conclusions: The Stentor was technically feasible in 10% to 40% of AAA candidates in this study, although deployment of the second limb was problematic in the bifurcated device. Introduction of the second-generation Vanguard endograft brought this study to an end.

Aortoenteric Fistula Caused by a Ruptured Stent-Graft: A Case Report

Purpose: To report a case of aortoenteric fistula secondary to endovascular abdominal aortic aneurysm (AAA) exclusion using the Stentor bifurcated endovascular graft. Methods and Results: Seventeen months after a successful endovascular AAA procedure, a male patient developed upper gastrointestinal bleeding. An aortoenteric fistula was diagnosed. At operation, the endograft fabric was found to be ruptured in an area of suture disruption between the nitinol stents. Coincidentally, a pre-existing inflammatory process might have caused adhesions between the bowel and the aortic wall, predisposing to fistula formation. The patient recovered after placement of a conventional aortic graft. Conclusions: Suture disruption between the internal support stents is a recognized complication in the first-generation Stentor device. Although the case described here is probably not typical of the consequences of this sequela, it does reinforce the need for continual periodic imaging to check for signs of graft disruption in Stentor endografts.