Type II endoleak in porcine model of abdominal aortic aneurysm

PURPOSE: The purpose of this study was to develop a reliable in vivo porcine model of type II endoleak resulting from endovascular aortic aneurysm repair (EVAR), for the study and treatment of type II endoleak. METHODS: Eight pigs underwent creation of an infrarenal aortic aneurysm, with a Dacron patch with preservation of lumbar branches. An indwelling pressure transducer was placed in the aneurysm sac. After 1 week the animals underwent EVAR with a custom-made Talent endograft. After another week the animals underwent laparoscopic lumbar artery ligation. Abdominal and pelvic computed tomography was performed after each procedure. Aneurysm sac pressure was measured in sedated and awake animals. RESULTS: All eight animals underwent successful creation of an aortic aneurysm and EVAR resulting in exclusion of the aneurysm sac. After creation of the aneurysm the sac mean arterial pressure (MAP) was 72.5 +/- 6.1 mm Hg and the sac pulse pressure was 44.8 +/- 8.7 mm Hg. Postoperative computed tomography scans demonstrated a type II endoleak from the lumbar branches in all animals. While aneurysm sac MAP (56.5 +/- 7.9 mm Hg; P <.01) and pulse pressure (13.6 +/- 4.1 mm Hg; P <.01) decreased after EVAR, sac pulse pressure remained, with type II endoleak. All animals underwent laparoscopic lumbar artery ligation, which resulted in further reduction in the sac MAP (38.3 +/- 4.6 mm Hg; P <.02) and immediate absence of sac pulse pressure (0 mm Hg; P <.01). Necropsy confirmed the absence of collateral flow in the aneurysm sac, with fresh thrombus formation in all animals. CONCLUSION: We present a reliable and clinically relevant in vivo large animal model of type II endoleak. CLINICAL RELEVANCE: We set out to show that aortic aneurysm sac pressurization caused by lumbar arterial flow in the setting of type II endoleak can be reproduced in an in vivo porcine model of endovascular aortic aneurysm repair. Indeed, in this model the aneurysm sac pulse pressure was a sensitive indicator of type II endoleak, correlating well with findings at computed tomography, and lumbar artery ligation eliminated the endoleak, as demonstrated on computed tomography scans and sac pressure measurement. Therefore we believe this in vivo large animal model can be instrumental in the study of many aspects of the physiologic features of type II endoleak.     

腔内隔绝术治疗腹主动脉瘤

目的探讨腹主动脉瘤（ＡＡＡ）腔内隔绝术的手术指征、手术方法、操作要点和存在的问题。方法１例高龄男性和多病并存的ＡＡＡ患者在全麻和选择性动脉造影动态监控下,用１１．０ｃｍ×２．６ｃｍ的内支撑－涤纶血管复合体,对ＡＡＡ进行了腔内隔绝术。结果术后１周和２０天分别行彩超和螺旋ＣＴ复查显示：复合体内径为２．２～２．４ｃｍ,通畅,无移位和扭曲。复合体壁外原ＡＡＡ腔内充满血栓,未探及通畅的腰动脉和肠系膜下动脉,ＡＡＡ外径无变化。复合体近端与ＡＡＡ颈前壁之间有一微裂隙,但对ＡＡＡ体影响不大。随访６个月,患者腹部搏动性肿块及左下肢间歇性跛行消失。结论ＡＡＡ腔内隔绝术避免了传统ＡＡＡ手术的各种缺点,而具简便、微创和疗效确实的优点,有良好的应用价值。     

Transluminally placed endovascular graft indications: thoracic aortic aneurysm and abdominal aortic aneurysm]

In 1991, Parodi et al described the first clinical use of a new technique for abdominal aortic aneurysm (AAA) repair using transluminally placed endovascular grafts (TPEG). Subsequently, in 1994 Dake et al reported the use of this new technique for the treatment of patients with aneurysms of the descending thoracic aorta. Since then, TPEG for the treatment of aneurysms have been clinically investigated in a number of centers. Initially, TPEG appeared to be an attractive alternative to standard surgical open repair, since they are less invasive and thereby reduce the operative risk in high-risk patients. The effectiveness and safety of TPEG have been reported by many investigators, and indications for this technique are increasing. However, the placement of TPEG within the artery by insertion via a remote site and fixation by attachment systems, such as various types of expandable stents, is completely different from conventional graft replacement. The long-term durability of TPEG is not yet known, and therefore we must remain cautious in patient selection. The cause and morphology of each aortic aneurysm determine whether TPEG are indicated. At present, TPEG is used to treat patients with aneurysms below the distal arch, and infrarenal abdominal aorta. However, indications in patients with aortic dissections are not clearly defined, because though the procedure is technically feasible, the effectiveness is not yet known and further investigation is required.     

胸主动脉夹层合并腹主夹层动脉瘤的一期腔内治疗

目的：探讨胸主动脉夹层动脉瘤合并腹主动脉夹层动脉瘤病人一期腔内隔绝术治疗的可行性、手术操作技巧及并发症防治原则。方法和结果：1例Stanford B型胸主动脉夹层动脉瘤合并腹主动脉夹层动脉瘤及双侧髂动脉瘤的病人于2006年3月在本中心接受了腔内隔绝术。MRA检查提示．主动脉弓降交界处开始出现夹层．真腔受压变窄,以胸腹交界处及腹主动脉中段最明显,最扁窄处为0．5cm;假腔在腹主动脉中段明显,最大径约5．0cm,假腔再人口位于左髂总动脉近端。双侧髂总动脉迂曲并呈瘤样扩张。腹腔干、肠系膜上动脉及双侧肾动脉均发自真腔。手术在全麻下进行：降主动脉植入规格为34-34-100mm的直管型Talent移植物,封闭夹层裂口：腹主动脉植入规格为AOI26-12-170mm Talent移植物,远端连接12．12．68mmTalent移植物至一侧髂外动脉,行双侧股-股转流。瘤体隔绝完全,手术约耗时300min,失血1000ml,透视6min,使用威视派克450ml。术后21d出院。术后随访半年,病人生活质量良好,复查CTA显示：移植物通畅,瘤腔内均完全形成血栓。结论：腔内隔绝术的微创特点使一期治疗Stanford B型主动脉夹层动脉瘤合并腹主动脉瘤成为一种比较安全的手术。主动脉长段隔绝也有利于降低截瘫的发生率。     

Reduction in aortic aneurysm size: Early results after endovascular graft placement

Purpose: Previous reports demonstrate initial technical success with transluminally placed endovascular grafts (TPEG) for the treatment of abdominal aortic aneurysms. However, long-term changes in the size of the aorta and aneurysmal segments are unknown. The purpose of this study was to determine aortic dimensions at several levels by computed tomographic (CT) scans 1 year after TPEG.Methods: Thirty-four patients underwent TPEG with 1-year CT scans. Patients were divided into three groups: group I, no perigraft leak; group II, early perigraft leak that sealed during the first year; and group III, persistent perigraft leak. Aortic minor and major diameters, perimeter, and area were measured at four locations: the celiac aorta, proximal neck, maximal aneurysm size, and distal neck.Results: There were 32 men and two women, with a mean age of 73 ± 8 years. In group I there were 20 patients (58%), and groups II and III had seven patients (21%) each. The overall mean aneurysm minor diameter decreased from 4.79 ± 0.68 cm at implantation to 4.39 ± 0.86 cm at 1 year ( p < 0.0001). The aneurysm sac decreased by 0.63 ± 0.58 cm in group I, and by 0.34 ± 0.24 cm in group II. In group III, however, the aneurysm sac increased by 0.19 ± 0.21 cm. Aneurysm size change did not correlate with inferior mesenteric or lumbar artery patency. The dimensions of the celiac aorta and proximal neck did not change significantly. However, diameter of the distal neck enlarged by 0.12 ± 0.27 cm ( p < 0.01).Conclusions: TPEG exclusion is associated with reduction of aneurysm size 1 year after implantation. Expansion of the aneurysms occurred with persistent perigraft leak. The aortic size at the celiac artery and proximal neck did not change. Dilation of the distal neck was minor but requires further long-term follow-up to determine clinical significance. (J Vasc Surg 1997;25:113-23.)     

Successful treatment of endotension and aneurysm sac enlargement with endovascular stent graft reinforcement

Abdominal aortic aneurysm (AAA) enlarges after successful endovascular repair because of endoleak, which is persistent blood flow within the aneurysm sac. In the absence of detectable endoleak, AAA may still expand, in part because of endotension, which is persistent pressurization within the excluded aneurysm. We report three patients who underwent successful endovascular AAA repair using the Excluder device (W. L. Gore & Associates, Flagstaff, Ariz). Although their postoperative surveillance showed an initial aneurysm regression, delayed aneurysm enlargement developed in all three, apparently due to endotension. Endovascular treatment was performed in which endograft reinforcement with a combination of aortic cuff and iliac endograft extenders were inserted in the previously implanted stent grafts. The endograft reinforcement procedure successfully resulted in aneurysm sac regression in all three patients. Our study underscores the significance of increased graft permeability as a mechanism of endotension and delayed aneurysm enlargement after successful endovascular AAA repair. In addition, our cases illustrate the feasibility and efficacy of an endovascular treatment strategy when endotension and aneurysm sac enlargement develops after endovascular AAA repair.     

Delayed aortic aneurysm enlargement due to endotension after endovascular abdominal aortic aneurysm repair

Abdominal aortic aneurysm (AAA) enlarges after successful endovascular repair, because of persistent blood flow within the aneurysm sac, or endoleak. In the absence of detectable endoleak, AAA may still expand, in part because of persistent pressurization within the excluded aneurysm, or endotension. We report three patients who underwent successful endovascular AAA repair in whom postoperative surveillance showed aneurysm regression, yet delayed AAA enlargement without demonstrable endoleak developed in all three patients. Endotension was confirmed in all three patients at elective open conversion. Our study underscores the significance of endotension as a mechanism of delayed aneurysm enlargement after successful endovascular AAA repair.     

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.     

犬胸腹主动脉瘤旷置术的血流动力学研究

目的 从血流动力学角度探讨胸腹主动脉瘤（TAAA）临置术的适用性及合理性，方法 8条杂种犬，依临床改良Hardy术式制作犬胸腹主动脉瘤旷置术模型，测量模拟瘤颈上方结扎不同程度时瘤腔内的压力，血流及人工血管内压力的变化。结果 不全结扎时模拟瘤腔内收缩压由术前的199.3mmHg(1mmHg=0.133kPa)降至82.9mmHg，舒张压由153.4mmHg降至73.6mmHg，脉压差降幅高达79.7%；血流量由79.1ml/min降为62.2ml/min；而人工血管内压结扎后期才逐渐降为103.5mmHg。结论 本术式在保证脏器，脊髓供血前提下，可明显降低胸腹主动脉瘤腔内的最高压力，平均压力，压力波动幅度及血流量，因此可有效降低动脉瘤的扩张速度，减少其破裂的可能性。     

Perirenal Fixation as an Independent Factor in Aortic Remodeling after Endovascular Aortic Aneurysm Repair

The purpose of our study was to evaluate the influence of perirenal fixation of endovascular aortic grafts on the rate of endoleak and aortic sac remodeling. Retrospective analysis of all patients (pts.) after undergoing endovascular aortic aneurysm repair (EVAR) at our institution was performed. Pre- and postoperative aortic dimensions were obtained from CT scans and angiograms. Intraoperative angiograms were reviewed and patients grouped by the proximity of the graft to the lowest renal arteries: group I: flush with the lowest renal artery; group II: 5 mm distal to lowest renal artery; and group III: >5 mm distal to lowest renal artery. Of the 96 grafts placed between 2000 and 2002, 44 were AneuRx (Medtronic, Santa Rosa, CA) and 52 were Ancure (Guidant, Menlo Park, CA) devices. There were 39 pts. in group I, 42 in group II, and 11 in group III (data on 5 pts. were not obtained). At 6 months, the mean decrease in sac diameter for all groups was 0.42 ± 0.08 cm (I: 0.56 ± 0.11 cm; II: 0.38 ± 0.11 cm; III: 0.6 ± 0.15 cm). There was no significant difference between each group. When perirenal fixation (group I) was compared with nonperirenal fixation (groups II and III), there was a significant difference in sac shrinkage at 6 months (p < 0.05, ANOVA). Group I had shorter necks and smaller aneurysms (2.2 ± 0.1 cm and 5.3 ± 0.1 cm) than those of groups II and III (2.7 ± 0.1 cm and 5.7 ± 0.1 cm, p < 0.05, ANOVA). There was no difference in aortic neck diameter or in aortic neck diameter to graft ratio. When controlled for the variables studied (AAA diameter, length of neck, diameter of neck, diameter of neck to graft ratio, and any endoleak by 6 months), logistic regression analysis identified perirenal fixation as the only significant factor in aortic sac shrinkage of >0.4 cm by 6 months (odds ratio = 16, p < 0.01). With the same variables, a linear regression model also identified perirenal fixation as the only predictive factor in aortic shrinkage (regression coefficient = 0.46, p < 0.05). The endoleak-free survival rate with perirenal fixation was 96 ± 5% and without it was 80 ± 7% (Kaplan Meier, p = 0.09, log rank). Perirenal placement of endovascular grafts is associated with a trend toward fewer endoleaks, and improved aortic sac shrinkage independent of aortic neck length, AAA diameter, diameter of neck, and endoleak. Failure to achieve perirenal placement of EVAG increased the likelihood of reduced or failed aortic sac shrinkage in this series.Presented at the Twenty-eighth Annual Meeting of the Peripheral Vascular Surgery Society, Chicago, IL, June 7, 2003.     

Comparative early and midterm results of open juxtarenal and infrarenal aneurysm repair

Background and aims Since the introduction of endovascular aortic aneurysm repair (EVAR) for aortic aneurysms, the number of juxtarenal aortic aneurysms (JRA) has been growing steadily due to selection bias (neck morphology for EVAR). This case-match study compares the perioperative outcome and midterm results of suprarenally clamped JRA with infrarenal aortic aneurysms (AAA). Methods From 1997 to 2004, patients who received open surgery with suprarenal clamping for JRA were included in the study and compared to matched patients with infrarenal clamping (AAA). Measurements analyzed were the in-hospital mortality and morbidity. Midterm results were obtained through clinical investigation and magnetic resonance angiography imaging. Results Thirty-five patients (mean age, 68.4 years; 30 male and 5 female) received suprarenal cross-clamping for JRA. The overall in-hospital mortality for JRA and for the controls (AAA) with elective aortic repair was 4.5% (6.1% JRA; 3% AAA, p = 0.058). The morbidity of JRA was elevated according to the rate of pulmonary complications (p = 0.021) and the need for re-operation (p = 0.019). The mean follow-up time was 2.3 years (range, 8–96 months). At follow-up, 28 patients (80%) from the JRA group and 29 patients from the AAA group (82.9%) were alive. Conclusion Open aortic surgery for JRA with the need for suprarenal cross-clamping shows a slightly elevated in-hospital mortality rate without statistical significance and equal midterm mortality results in comparison with infrarenally clamped aortic aneurysms.     

Evaluation of pressure transmission and intra-aneurysmal contents after endovascular repair using the Trivascular Enovus expanded polytetrafluoroethylene stent graft in a canine model of abdominal aortic aneurysm

OBJECTIVE: Endotension has been defined as persistently increased pressure within the excluded sac of an abdominal aortic aneurysm (AAA) resulting in increasing aneurysm size after endovascular repair in the absence of endoleak. Devices that use expanded polytetrafluoroethylene (ePTFE) have been associated with the development of endotension and continued AAA enlargement. In this study, intra-aneurysmal pressure and aneurysm content were evaluated after endovascular repair with the Enovus ePTFE stent graft in a canine model. METHODS: Prosthetic ePTFE aneurysms, each containing a solid-state, strain-gauge pressure transducer, were implanted in the infrarenal aorta of 13 mongrel dogs (25-35 kg). A second pressure transducer was inserted into the native aorta for systemic arterial pressure measurement. The stent graft was then deployed to exclude the aneurysm via distal aortic access. Comparison was made among three distinct stent grafts: the Trivascular Enovus (nonporous ePTFE; four animals), the original Gore Excluder (porous ePTFE; five animals), and the Medtronic AneuRx (Dacron; four animals). Daily systemic and intra-AAA pressures were measured for 4 weeks. Intra-aneurysmal pressures were indexed to simultaneously measured systemic pressures. After 4 weeks, the aorta, the prosthetic aneurysm, and its contents were harvested, photographed, and processed for histologic investigation with hematoxylin and eosin and Masson trichrome staining. RESULTS: Within 24 hours after exclusion, the mean arterial pressure and pulse pressure within the AAA sac tapered to less than 20% of systemic pressure for all three stent graft types. Throughout the postoperative period, significantly lower indexed intra-aneurysmal pressures were present in the Enovus- and AneuRx-treated aneurysms as compared with those treated with the original Excluder stent graft (0.05 +/- 0.04, 0.16 +/- 0.06, and 0.06 +/- 0.03 for the Enovus, Excluder, and AneuRx, respectively). Histologic analysis of the Enovus-treated aneurysms demonstrated intraluminal content characterized almost entirely by erythrocytes and infrequent white blood cells without the fibrin organization-characteristics of acute or chronic thrombus. This contrasted with the content of the Excluder-treated aneurysms, which contained poorly organized fibrin deposition suggestive of acute thrombus, and of the AneuRx-treated aneurysms, which demonstrated mature, well-organized collagenous connective tissue. CONCLUSIONS: Exclusion of the AAA with the Enovus stent graft resulted in nearly complete elimination of intra-aneurysmal pressure in this model. Histologic analysis of the aneurysm content further suggested complete exclusion, including elimination of circulating clotting factors and fibroblasts responsible for thrombus formation and reorganization. Ultimately, clinical evaluation will be necessary to demonstrate the effectiveness of this stent graft in preventing the development of endotension.     

Aortic aneurysm pulsatile wall motion imaged by cine MRI: a tool to evaluate efficacy of endovascular aneurysm repair?

OBJECTIVES: to evaluate cine MRI as a means of determining the two-dimensional pulsatile wall motion (2D-PWM) of abdominal aortic aneurysm (AAA). DESIGN: prospective study of 21 patients with AAA. 2D-PWM was defined as change in cross-sectional area. RESULTS: the median diastolic area was 28 cm(2) (intraquartile range, IQR, 22-31 cm(2)) and the median (IQR) 2D-PWM was 0.25 (0.10-0.40) cm(2). Assuming that the AAA is circular in cross-section this represents a median (IQR) diameter increase of 0.3 (0.1-0.4) mm. However, local wall displacements up to 2 mm were present in varying directions, without significant change in surface area. CONCLUSION: AAA PWM is negligible and may not therefore be a potential tool to assess efficacy of endovascular aneurysm exclusion.     

Simultaneous endovascular exclusion of thoracic aortic aneurysm with open abdominal aortic aneurysm repair.

BACKGROUND: The treatment of aneurysms at multiple sites within the aorta is problematic. METHODS: Between March 2002 and June 2003 in the Department of General, Vascular and Transplant Surgery, Medical University of Warsaw six patients with coexisting abdominal and descending thoracic aortic aneurysms underwent simultaneous open abdominal aortic aneurysm (AAA) repair and endoluminal thoracic aortic aneurysm (TAA) repair. The indication for a combined procedure was a diagnosed descending TAA and AAA with no significant risk factors for open aortic surgery or technical contraindications for endovascular treatment of TAA. RESULTS: One patient died in the peri-operative period while the other five patients all recovered well after surgery and were discharged with both aneurysms excluded. CONCLUSION: Endovascular treatment of TAA combined with a simultaneous open AAA repair is an efficient and relatively safe treatment modality in patients with TAA and AAA disqualified from endovascular repair. The fact that thoracotomy is not a necessity significantly lowers the complication rate in these patients.     

Response of plasma matrix metalloproteinase-9 to conventional abdominal aortic aneurysm repair or endovascular exclusion: implications for endoleak

PURPOSE: Matrix metalloproteinases are enzymes capable of breaking down all of the components of the extracellular matrix and have been implicated in the development of aneurysm formation. Because matrix metalloproteinase-9 (MMP-9) levels are elevated in aortic aneurysmal tissue and in that patient plasma, we hypothesized that plasma MMP-9 levels should decrease significantly after conventional and endovascular infrarenal abdominal aortic aneurysm (AAA) repair but that plasma MMP-9 levels would remain elevated in patients with endoleaks. METHODS: A sandwich enzyme-linked immunosorbent assay was used to measure plasma levels of MMP-9 in patients with AAA who underwent conventional (n = 26; mean age, 71.5 years) and endovascular (n = 25; mean age, 76.4 years) AAA repair. Levels were drawn before surgery and at 1 month and 3 months after surgery. Eight patients for endovascular repair had endoleaks identified on postoperative computed axial tomographic scans. RESULTS: No correlation existed between preoperative plasma MMP-9 levels when compared with age, gender, or aneurysm diameter. No significant difference in preoperative plasma MMP-9 levels or AAA diameter was identified between patients with conventional repair compared with endovascular repair. Of the 51 patients, 33 had follow-up samples available for analysis. A significant increase in mean plasma MMP-9 levels was noted 1 month (149.5 +/- 40.1 ng/mL) after conventional AAA repair compared with preoperative levels (83.9 +/- 26.1 ng/mL; P <.05) and remained elevated 3 months after surgery (129.8 +/- 56.6 ng/mL). In those patients who underwent endovascular aneurysm exclusion without endoleak, a significant decrease in mean plasma MMP-9 levels was noted at 3 months (27.4 +/- 5.2 ng/mL) when compared with preoperative values (60.8 +/- 8.8 ng/mL; P <.01). In contrast, patients with endoleak after endovascular exclusion did not have a significant decrease in plasma MMP-9 levels at 3 months. CONCLUSION: Plasma MMP-9 levels remain elevated for as much as 3 months after conventional AAA repair, whereas successful endovascular exclusion of an AAA results in decreased plasma MMP-9 levels by 3 months. MMP-9 may have clinical value as an enzymatic marker for endoleak after endovascular AAA exclusion.     

A canine model to study the significance and hemodynamics of type II endoleaks

OBJECTIVE: The clinical significance of Type 2 endoleak after endovascular repair of abdominal aortic aneurysms (AAA) remains incompletely delineated. This study describes the development of a novel canine model that allows for continuous monitoring of intraaneurysmal pressure in the setting of Type 2 endoleak. METHODS: Infrarenal AAA were created in 10 mongrel dogs by implanting a prosthetic aneurysm containing an intraluminal, solid-state, strain gauge pressure transducer which is able to measure pressures in both solid and liquid media. A segment of native aorta with two or more patent side branch vessels was reimplanted into the prosthetic aneurysm using a Carrel patch. Four animals had two lumbar vessels implanted; two had two lumbar vessels and the caudal mesenteric artery implanted, and four control animals had no vessels reimplanted. Retrograde flow in the aneurysmal side branches caused a Type 2 endoleak after the aneurysm was excluded from antegrade flow by deploying a stent graft. Both systemic and intra-sac pressures were measured daily for up to 90 days after endovascular exclusion and indexed to systemic pressure. Endoleak patency and flow were assessed with digital subtraction angiography, duplex ultrasound, and cine-magnetic resonance angiography (MRA). Histological characterization of the intraaneurysmal contents was performed. RESULTS: Before endovascular exclusion, the systolic, mean arterial, and pulse pressure within the aneurysmal sac closely matched that of the systemic circulation (systolic, 0.96 +/- 0.22; mean, 0.94 +/- 0.21; pulse pressure, 0.97 +/- 0.22) (R value, 0.97). Endovascular exclusion in animals with no collateral side branch vessels resulted in no endoleak and significantly reduced intraaneurysmal pressure when compared to systemic pressure, with systolic, mean arterial, and pulse pressure 0.172 +/- 0.05, 0.137 +/- 0.05, and 0.098 +/- 0.02, respectively (P < 0.001). In animals with Type 2 endoleaks, the pressures were lower than systemic pressure, but statistically significant in their difference from the control group. The systolic pressure of those with Type 2 endoleaks was 0.702 +/- 0.048; mean arterial pressure was 0.784 +/- 0.028, and pulse pressure was 0.406 +/- 0.031 when indexed to systemic pressure (P < 0.001). Cine-MRA and Duplex ultrasound documented persistent patency of the Type 2 endoleaks throughout the study period in animals with multiple side branches. CONCLUSION: Intraaneurysmal pressure in the setting of Type 2 endoleaks may be accurately determined using this canine model. Intraaneurysmal pressure is maintained at a significant level in the context of this retrograde collateral perfusion, suggesting that persistent Type 2 endoleaks are of clinical significance. This model may serve to allow further evaluation and characterization of Type 2 endoleaks.     

Impact of exclusion criteria on patient selection for endovascular abdominal aortic aneurysm repair

PURPOSE: Wide-ranging predictions have been made about the usefulness of endovascular repair for patients with abdominal aortic aneurysms (AAAs). The availability of US Food and Drug Administration-approved devices has removed the restrictions on patient selection, which had been controlled by device trials. This study examined the applicability of endovascular AAA repair and identified the anatomic barriers to successful endovascular AAA repair that should guide future device development. METHODS: All patients who came to our institution for infrarenal AAA repair between April 1998 and June 2000 were offered evaluation for endovascular repair. Thin-cut spiral computed tomography scans and arteriograms were obtained on all patients, and their anatomic characteristics were prospectively entered into a database. A wide selection of available devices allowed the treatment of diverse AAA anatomic features. RESULTS: A total of 307 patients were examined (264 men, 43 women). Of these, 204 patients (66%; 185 men, 19 women) underwent endovascular repair, and 103 patients (34%, 79 men, 24 women) were rejected. Reasons for exclusion included short aneurysm neck (56, 54%), inadequate access because of small iliac arteries (48, 47%), wide aneurysm neck (41, 40%), presence of bilateral common iliac aneurysms extending to the hypogastric artery (22, 21%), excessive neck angulation (14, 14%), extensive mural thrombus in the aneurysm neck (10, 10%), extreme tortuosity of the iliac arteries (10, 10%), accessory renal arteries originating from the AAA (6, 6%), malignancy discovered during the examination (5, 5%), and death during the examination interval (2, 2%). Rejected patients had an average of 1.9 exclusion criteria (range, 1 to 4). A disproportionate number of women were excluded because of anatomic findings (P = .0009). Although 80% of patients who were at low risk for surgery qualified for endovascular repair, only 49% of our patients who were at high risk for surgery were acceptable candidates (P < .001). Of the 103 patients who were excluded, 34 (33%) underwent open surgical repair, and the remaining 69 (67%) were deemed to be unfit for open surgery. Three patients (1.4%) failed endograft placement because of inadequate vascular access. CONCLUSION: Most infrarenal AAAs (66%) can be treated with endovascular devices currently available commercially or through US Food and Drug Administration-approved clinical trials. However, patients who are at high risk for surgery and might benefit most from endovascular repair are less likely to qualify for the procedure (49%). Men (70%) are more likely than women (40%) to meet the anatomic criteria for endografting. Difficulties with vascular access and attachment site geometry predominate as reasons for exclusion. Our findings suggest that smaller profile devices, which can negotiate small and tortuous iliac arteries, are needed. Proximal and distal attachment site problems require devices that can accommodate wide and angulated attachment necks and achieve short seal zones.     

Endovascular Repair of a ruptured abdominal aortic and iliac artery aneurysm with an acute iliocaval fistula secondary to lymphoma

Abdominal aortic aneurysms (AAA) are common and generally asymptomatic unless rupture occurs. A 3 to 4-cm AAA has a 1-2% risk of rupture over 5 years. We present the case of an 85-year-old male with a history of chronic lymphocytic leukemia, a 3-cm infrarenal AAA, and a 2-cm right common iliac artery aneurysm whose AAA ruptured and who developed an acute iliac artery–to–vena cava fistula secondary to eroding adenopathy from an aggressive low-grade lymphoma. Initially, an open repair was attempted but access to the aorta was not possible because of complete encasement of the infrarenal and suprarenal aorta with tumor that was clinically invading the aortic wall. Secondary tumor invasion into the aorta is a rare complication. An endovascular repair was accomplished with successful exclusion of both the aneurysm and the iliocaval fistula. Endovascular repair provides a valuable alternative in the "hostile abdomen" when standard open repair may be hazardous or impossible.     

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

Our objective was to evaluate the effect of preoperative aneurysm and aortic neck diameter on clinical outcome after infrarenal abdominal endovascular aneurysm repair (EVAR). Data of patients in the European Collaborators Registry on Stent-Graft Techniques for Abdominal Aortic Aneurysm Repair (EUROSTAR) registry base who underwent EVAR with Talent stent grafts were analyzed. Patient characteristics and clinical outcomes were compared among four groups defined by preoperative abdominal aortic aneurysm (AAA) and proximal aortic neck diameter: A, AAA ≤60 mm and neck ≤26 mm; B, AAA >60 mm and neck ≤26 mm; C, AAA ≤60 mm and neck >26 mm; and D, AAA >60 mm and neck >26 mm. Over a 7-year period, 1,317 patients underwent EVAR. Patients in groups B and D were significantly older and had a higher American Society of Anesthesiologists score compared with groups A and C (p=0.002 and 0.003, respectively). Mortality rate was highest in group D (p=0.002), as were rupture and conversion rates (p=0.015 and 0.037, respectively). This study demonstrates that patients with an AAA >60 mm and a proximal aortic neck >26 mm have worse clinical outcome after EVAR. Presented at the Fifteenth Annual Winter Meeting of the Peripheral Vascular Surgery Society, Steamboat Springs, CO, January 28-30, 2005.     

Reduced pulsatile wall motion of abdominal aortic aneurysms after endovascular repair

Purpose: The reduced size of abdominal aortic aneurysms (AAAs) after endovascular repair suggests lowered intraaneurysmal pressure. In the presence of endoleaks, the size is not decreased. Although postoperative intraaneurysmal pressure is difficult to record, the pulsatile wall motion (PWM) of aneurysms can be measured noninvasively. The aim of this study was to assess the PWM of AAAs before and after endovascular repair and to relate the change in the PWM to aneurysmal size and presence of endoleaks. Methods: Forty-seven patients underwent endovascular repair of an AAA. The aneurysm diameter and PWM were measured with the use of ultrasonic echo-tracking scans preoperatively; at 1, 3, and 6 months; and thereafter biannually. Fifteen aneurysms developed endoleaks, whereas 32 were completely excluded. The leaks were characterized with the use of computed tomographic scanning and angiography. Median follow-up was 12 months (interquartile range, 5 to 24 months). Results: The preoperative PWM of the aneurysms was 1.0 mm (range, 0.8 to 1.3 mm). After complete endovascular exclusion, the PWM was 25% (range, 16% to 37%) of the preoperative value (p < 0.001), and aneurysm diameter decreased by 8 mm (range, 6 to 14 mm) (p < 0.001). After 18 months, no further diameter reduction occurred. In three patients without endoleaks but with enlarging aneurysms, the postoperative PWM showed less reduction (p < 0.05). Aneurysms with endoleaks showed no diameter decrease, and the postoperative PWM was 50% higher than that in the totally excluded cases (p < 0.01). In five patients with transient endoleaks, the PWM was reduced after leakage ceased (p < 0.05). Leaks of various sources displayed similar PWM. Conclusion: The size and PWM of aneurysms are reduced after endovascular repair. The diameter reduction may cease after 1.5 years. Endoleaks are associated with higher PWM than expected. Pressure may be transmitted without evidence of leaks. (J Vasc Surg 1998;27:624-31.)