Endovascular repair of aortic aneurysms: critical events and adjunctive procedures

OBJECTIVE: We sought to define the learning curve relative to the incidence and range of intraoperative problems and to establish guidelines for troubleshooting during the endovascular repair of infrarenal aortic aneurysms. METHODS: We prospectively evaluated our first 75 consecutive cases over a 12-month period and focused on perioperative critical events and adjunctive procedures as categorical outcome measures collected during the operation. Patients were separated into three groups on the basis of the date of their operation, such that group 1 consisted of our first 25 cases, group 2 our next 25 cases, and group 3 our last 25 cases. RESULTS: At least one critical event and adjunctive procedure marked 67 (89%) of 75 cases. In 51%, there were at least two critical events and adjunctive procedures. There were no immediate open conversions or intraoperative deaths. Access problems occurred in 28% of the 75 cases and were addressed by use of brachial-femoral artery access (30%), iliac artery/aortic bifurcation balloon angioplasty (8%), and iliofemoral conduits (4%). Graft foreshortening was the most common deployment event (44%), necessitating distal covered extensions. Iliac graft limb twists and kinks occurred in 12% of cases and were managed with balloon angioplasty and uncovered stents. General incidents included balloon ruptures (10%), arterial dissections (6%), iliac artery rupture (2.6%), and lower extremity ischemia (4%). The two cases of iliac artery rupture were managed with distal covered extensions, and there were no cases of atheroemboli. Intraoperative endoleaks were encountered in 44% of the cases and included proximal attachment sites (15%), distal attachment sites (9%), type 2 sources, and "blushes." Management of intraoperative endoleaks included proximal/distal covered extensions and re-ballooning. Our 30-day endoleak rate was 20%. The incidence of critical events did not decrease in the latter one third compared with the first two thirds of cases. CONCLUSIONS: Critical events occur frequently during endovascular repair of aortic aneurysms. The intraoperative problems range from the common endoleaks, access and deployment issues, and balloon ruptures, to rare but life-threatening complications such as iliac artery rupture. A toolbox of accessories that includes wires, catheters, large balloons, covered proximal and distal extensions, and uncovered stents is essential given the frequency of adjunctive procedures. Successful aortic endografting requires more than mere familiarity with basic endovascular techniques.     

Intra- and interobserver variability in the measurements of abdominal aortic and common iliac artery diameter with computed tomography. The Troms? study.

OBJECTIVES: to assess intra- and interobserver variability in the measurement of aortic and common iliac artery diameter by means of computed tomography (CT). DESIGN: reproducibility study. MATERIAL AND METHODS: three radiologists performed measurements of aortic diameter at five different levels and of both common iliac arteries with CT. Fifty-nine subjects were examined, 29 with and 30 without abdominal aortic aneurysms (AAA) as assessed by ultrasound. RESULTS: intraobserver variability varied between radiologists, measurement plane (anterior-posterior vs transverse) and measurement level. The interobserver variability was markedly higher at the bifurcation than at the suprarenal level and higher than intraobserver variability for measurements at all levels. Both intraobserver and interobserver variability increased with increasing vessel diameter and were largest in patients with AAA. The absolute intraobserver difference of the maximal infrarenal aortic diameter was 2mm or less in 94% of intraobserver pairs. The corresponding interobserver difference was 82%. CONCLUSIONS: interobserver variability of CT measurements of aortic and common iliac artery diameter is not negligible and should be taken into account when making clinical decisions. When assessing change in aortic diameter, previous CT-scans should be reviewed simultaneously as a routine to exclude interobserver variability.     

Early Vascular Complications after Endovascular Repair of Aortoiliac Aneurysms

The purpose of this study was to estimate the frequency of and review the treatment options for intraoperative endograft access-related vascular complications and early postoperative vascular complications of endovascular repair for aortoiliac aneuryms (EVAR). Between February 1998 and April 2000, 53 patients (46 males, 7 females) with aneurysms of the abdominal aorta (AAA) and iliac arteries were treated with endovascular grafts (48 AAA, and 5 iliac aneurysms). All procedures were performed using open exposure of the femoral arteries. One patient with an AAA was converted to open repair (primary technical success, 98.1%). We recorded the need for adjunctive vascular procedures or intervention to the access arteries (iliofemoral) or the endograft because of thrombosis or distal embolization. Events were classified as either intraoperative, early postoperative (< 30 postoperative days), or late postoperative. Their etiology and treatment were recorded. The results were compared to those from other series reported in the literature and to published registry data. From our results we concluded that the need for adjunctive vascular procedures to the iliofemoral arteries at the time of EVAR is significant. These procedures are necessary to either repair damage to the access arteries from the delivery system or provide a conduit for graft delivery in cases where the access arteries are inadequate. Early postoperative vascular complications are due to technical factors resulting in residual graft limb stenoses. Both intraoperative and early postoperative vascular complications after EVAR are more common in female patients. These complications can be effectively treated with a variety of open surgical and transfemoral endovascular techniques.     

A prospective study of clinically and endoscopically documented colonic ischemia in 100 patients undergoing aortic reconstructive surgery with aggressive colonic and direct pelvic revascularization, compared with historic controls

Clinically and endoscopically proved ischemia of the colon complicates elective aortic reconstruction in 1% to 2% and 6% to 7% of cases, respectively. Operative mortality exceeds 60% when transmural infarction occurs. A prospective study of colonic ischemia was undertaken in 100 male patients (mean age, 62.4 +/- 7.9 years) undergoing operation for aortic aneurysms (58) or aortoiliac occlusive disease (42). Conventional aortic surgery was undertaken in 88 patients, and in 12 patients adjunctive procedures to enhance colonic perfusion were performed 14 times, including IMA reimplantation (8), direct bypass to the internal iliac artery (4), and anastomosis of an aortofemoral bypass limb to adjacent common iliac artery (2). Colonoscopy was performed within 24 to 48 hours of aortic reconstruction. Three patients had endoscopic evidence of colonic ischemia. Transmural infarction did not develop in any patient, and bowel resections or diverting colostomies were not necessary. Three patients died, none manifesting colonic ischemia. The 12% utilization of adjunctive procedures to enhance blood flow in the colon was substantially greater than the 4% frequency of an earlier experience from our institution in which nearly half of the 5.7% operative mortality was attributed to colonic infarction. Attention to factors contributing to ischemia of the colon, and more frequent adjunctive revascularization of the colon, may lessen this complication of aortic reconstructive surgery.     

Use of hybrid aortic stent grafts for endovascular repair of abdominal aortic aneurysms: indications and outcomes

BACKGROUND: Only two aortic stent grafts (Ancure-Guidant, Menlo Park, CA, and AneuRx-Medtronic, Sunnyvale, CA) have been FDA-approved for endovascular aortic aneurysm repair (EndoAAA). These grafts differ significantly in construction and clinical advantage, and combining components of these grafts (hybrid graft) is occasionally necessary. The role and outcome of hybrid aortic stent grafts is unknown. METHODS: All EndoAAA procedures during an 18-month period (10/99-4/01) were reviewed using the hospital record and a computer registry. Endografts were classified as hybrid if components from more than one type of stent graft were used or standard if constructed from only one stent graft type. Hybrid grafts were further classified as "anticipated" or "unanticpated." Outcomes were compared between hybrid and standard grafts using Fisher's exact test. RESULTS: One hundred forty-five EndoAAA repairs were performed (AneuRx, 67; Ancure, 70; and custom-made, 8) of which 14 (9.6%) were hybrid grafts. The majority of hybrid grafts (11) were constructed by adding AneuRx aortic or iliac cuffs to Ancure grafts. In most cases, the need for a hybrid graft was unanticipated (10) and related to an intraoperative proximal type I endoleak (7). Conversion to open operation was avoided in six patients by constructing hybrid grafts. When anticipated (4), hybrid grafts were constructed to treat complex iliac aneurysms. Outcomes in all categories were similar (P > 0.05) for hybrid vs standard grafts: technical success (93 vs 99%), conversion toopen AAA (7.1 vs 2.3%), vascular complications (7.1 vs 7.6%), systemic complications (21 vs 11%), endoleak (15 vs 14%), and rupture (0 vs 0%). CONCLUSIONS: The short-term safety and effectiveness of hybrid grafts are similar to those of standard grafts. Combining graft components to create hybrid grafts may increase the ability to treat complex iliac aneurysmal disease and may reduce conversions to open AAA repair. Thus, access to multiple graft types may be an important factor in the success and safety of EndoAAA repair.     

Technique for iliac artery reconstruction in abdominal aortic aneurysm repair.

The aim of this retrospective study was to evaluate the technique for iliac artery reconstruction in abdominal aortic aneurysm repair, when external and internal iliac arteries were required to reconstruct individually. Among 203 elective infrarenal abdominal aortic aneurysm repairs, 22 patients (10.8%) required individual reconstruction of bilateral or unilateral iliac arteries, including 56 external or internal iliac arteries. Mainly, three types of procedures were performed: (1) the external iliac artery was anastomosed to the end of the bifurcated graft limb in an end-to-end manner, and the internal iliac artery was attached to the side of the external iliac artery, (2) the external iliac artery was anastomosed to the end of the bifurcated graft limb in an end-to-end manner and the internal iliac artery was bypassed with the use of a straight prosthetic graft extending from the limb of the bifurcated graft, and (3) the internal iliac artery was anastomosed to the end of the bifurcated graft limb in an end-to-end fashion, and the external iliac artery was sewn to the side of the graft limb. In these three types of procedures, the third technique was the easiest and simplest anatomically.     

Endovascular abdominal aortic aneurysm (AAA) repair since the FDA approval. Are we going too far?

BACKGROUND: Since the FDA approval of endovascular devices for abdominal aortic aneurysm (AAA) repair, clinicians have been relaxing the strict inclusion criteria of the clinical trials. We have reviewed our experience during and after the clinical trials to examine changes in patient selection, technical aspects of the procedure, and outcome. METHODS: A review of a prospectively compiled database of all endovascular AAA repairs performed at our institution was performed. RESULTS: Endovascular AAA repair was attempted in 130 patients: 46 (35.4%) as a part of clinical trials (Group I), and 84 (64.6%) since the FDA approval of the devices (Group II). Significant differences in patient selection included: a higher proportion of short (<15 mm) proximal necks in Group II (28.6 vs 0.0%, p<0.001), and a higher proportion of iliac occlusive disease in Group II (48.8 vs 15.4%, p=0.001). Additional trends suggested that Group II AAA's were more complex, including increased proximal neck angulation, increased proximal calcification, increased presence of proximal thrombus, and increased iliac tortuosity. Significant differences in technical aspects of the procedure included increased usage of iliac angioplasty (46.4 vs 13.3%, p<0.001), iliac stenting (31 vs 8.9%, p<0.01), and conduit access to the external iliac artery (10.7 vs 0%, p=0.03) in Group II. Analysis of outcome revealed a decreased incidence of the following in Group II cases: conversions to open repair (2.4 vs 10.9%), lower extremity ischemia (3.6 vs 13.0%), and graft limb occlusion (2.4 vs 8.7%). Other major perioperative complications did not differ significantly between the 2 groups. However, although the overall rate of any endoleak noted in the postoperative course was decreased in Group II cases (26.2 vs 32.6%), the incidence of proximal or distal attachment site leaks has increased (11.9 vs 4.3%, p=0.14). Although this comparison did not reach statistical significance, the magnitude of the increase is concerning. CONCLUSIONS: Although we have been able to offer endovascular AAA repair to a larger number of patients since FDA approval, endovascular management of increasingly complex proximal necks and increased iliac artery disease appears to have increased the incidence of attachment site endoleaks. Although many of these leaks have been successfully managed with adjunctive endovascular procedures, their increasing incidence is worrisome and suggests that we may need to re-evaluate current inclusion criteria for using this technology. Although difficult access issues have been handled with adjunctive procedures, the presence of a short, angulated proximal neck may be difficult to overcome, and may not be well suited for endovascular repair with the currently available devices.     

Brachial artery catheterization to facilitate endovascular grafting of abdominal aortic aneurysm: safety and rationale

PURPOSE: Endovascular treatment of abdominal aortic aneurysms (AAAs) is a technically demanding procedure that is based on the complexity and multiplicity of steps and the guidewire and catheter manipulations required. Brachial artery catheterization is an adjunctive technique that can facilitate the placement of an endoluminal prosthesis. METHODS: Brachial access was used during endoluminal AAA repair in 79 of 103 consecutive patients with a modular-design stent-graft prosthesis at two institutions. RESULTS: Left brachial access facilitated (1) angiography to guide juxtarenal device deployment, (2) antegrade contralateral limb access, (3) device delivery through disadvantaged iliac arteries by means of a brachial femoral wire, (4) access to renal arteries when necessary, and (5) catheter exchanges and a reduction in fluoroscopic positional changes. Complications included one puncture-site pseudoaneurysm, seven hematomas, and 29 patients with extensive ecchymosis. The length of stay was not prolonged in any case. There were no embolic, oculocerebral, or ischemic upper extremity events. CONCLUSIONS: Brachial artery catheterization, as an adjunctive technique to endoluminal AAA repair, offers noteworthy technical advantages with few, but self-limiting complications.     

Measurement variance in limb length discrepancy: clinical and radiographic assessment of interobserver and intraobserver variability

The purpose of this study was to assess interobserver and intraobserver variability in the assessment of clinical and radiographic measurement of lower limb length discrepancy. Clinical measurements included direct measurement with a tape measure from anterior superior iliac spine (ASIS) to lateral malleolus and ASIS to medial malleolus as well as block measurement. Slit scanogram radiographic measurement was also evaluated. All three clinical measurements had excellent reliability, but the relatively large mean differences and the large 95% confidence intervals for clinical measurements limit the usefulness of these techniques. Slit scanogram measurement was the most reliable measurement technique. The intraobserver variance of direct slit scanogram measurement included intraclass correlation coefficient of 0.99, mean difference of 0.1 cm, and 95% confidence interval of 0.4 cm. Results were not influenced by patient age or body mass index. Slit scanogram measurement is the preferred method for assessment of limb length discrepancy. The direct slit scanogram measurement described in the text follows the mechanical axis line of the leg in the "at ease" standing position described by Paley. Direct measurement using a measuring tape on a full-length slit scanogram is more reliable than indirect measurement using horizontal lines drawn to a radiolucent ruler that is positioned by a technician, since direct measurement avoids errors due to nonparallel positioning of the limb relative to the ruler, and direct measurement also avoids errors due to non-horizontal lines drawn from standard bony landmarks to the ruler. The ideal radiographic measurement technique would have high reliability and accuracy and would minimize or eliminate radiation.     

Intraobserver and interobserver agreement in anal endosonography

BACKGROUND: The aim of this study was to determine intraobserver and interobserver agreement for sonographic measurements of anal canal structures using anal endosonography (AES), and to determine interobserver agreement for the diagnosis of anal sphincter disruption. METHODS: Fifty-one consecutive patients referred for AES for the investigation of possible sphincter abnormality were examined. Studies were reviewed by two observers who measured anal canal structures at defined levels and locations, and recorded an opinion on sphincter integrity. Repeated measurements made by each observer were compared to determine intraobserver agreement, and measurements and diagnoses were compared between observers to determine interobserver agreement. RESULTS: Intraobserver agreement was better than interobserver agreement for measurements of anal canal structures. Interobserver limits of agreement for external sphincter measurements spanned 5 mm, whereas those for the internal sphincter spanned 1.5 mm. Interobserver agreement for diagnosis of sphincter disruption and internal sphincter echogenicity was very good (kappa = 0.80 and 0.74 respectively). CONCLUSION: The limits of agreement for intraobserver and interobserver measurements of anal canal structures on AES have been defined. Interobserver assessment of sphincter disruption is very good.     

Secondary procedures after endovascular aortic aneurysm repair

PURPOSE: The purpose of this study was to evaluate the incidence, distribution, and indications of secondary procedures after endovascular aortic aneurysm repair (EAR). METHODS: At a single institution, 179 patients underwent EAR with four different endografts (AneuRx, n = 117; Zenith, n = 49; Ancure, n = 12; and Talent, n = 1). The vascular section database was queried for patients who needed secondary procedures after the original EAR. The mean time from EAR to the termination of the study was 27.0 +/- 16.7 months. Type I or III endoleaks were treated aggressively. Type II endoleaks were treated only in the presence of aneurysm expansion. RESULTS: Thirty-five (35/179; 19.6%) secondary procedures were performed in 32 patients. Indications for secondary procedures included 14 limb occlusions or stenoses (40.0%), 13 endoleaks (37.1%), six endograft migrations (17.1%), one delayed aneurysm rupture (2.8%), and one device malfunction (2.8%). Seven of the 10 early (<90 days) limb failures (70%) occurred within the first 60 patients. At that time, a protocol with aggressive external iliac artery evaluation was adopted. In the next 125 patients, the rate of early limb occlusion or stenosis was 2.4% (P =.025, with Fisher exact test). Distribution of secondary procedures included 23 endoluminal interventions (65.7%; angioplasty +/- stent placement, thrombolysis, endocuff placement, embolization), eight traditional peripheral procedures (22.9%; femoral-femoral bypass, thrombectomy), two laparoscopic interventions (5.7%; inferior mesenteric artery ligation), and two laparotomies (5.7%; delayed conversions). Interventions for limb occlusion or stenosis occurred earliest (3.5 +/- 5.4 months; P <.05, with analysis of variance), followed by treatment of endoleaks (14.3 +/- 12.9 months) and migration (27.5 +/- 10.4 months). The one delayed rupture occurred at 15.3 months. CONCLUSION: Secondary procedures after EAR are common. Reinterventions can be grouped temporally on the basis of indication. Treatment for limb ischemia is predominately early (>/=3 months), whereas treatment for endoleaks occurs at approximately 1 year and interventions for migration predominate after 2 years.     

Abdominal Aortic Aneurysm Measurements for Endovascular Repair: Intra- and Interobserver Variability of CT Measurements

OBJECTIVES: to evaluate the intra- and interobserver variability in measurements of the aorta and iliac arteries in patients with abdominal aortic aneurysms (AAAs) considered for endovascular repair using computed tomography angiography (CTA). METHODS: the diameter of the neck, aneurysm, right and left iliac artery were measured by 5 observers in 10 consecutive patients. Measurements were performed on hard copy using a ruler and on a workstation using an electronic caliper. RESULTS: the intraobserver variability showed a decrease going from hard copy to workstation in the standard deviation of the differences of the paired observations for the neck from 3.54 mm to 1.18 mm; for the aorta from 4.16 to 1.72 mm; for the right iliac from 1.87 to 1.01 mm; for the left iliac from 2.07 to 0.87 mm. The interobserver variability showed a similar decrease for the neck in all ten pairs of observers; for the aorta in two, for the right iliac and left iliac in five. However, the difference between observers regularly exceeded 2 mm. CONCLUSION: the use of a workstation and electronic calipers results in lower intra- and interobserver variability. However, the results still show a clinically relevant difference between the observers. Therefore, it is necessary to develop an automatic observer-independent measurement technique.     

经食管心脏超声应用于心脏手术患者肾脏血流测定的可行性研究

背景目前尚缺乏可靠的方法监测手术中患者的肾脏血流,本研究中我们评估了经食管心脏超声测定心脏手术患者左肾血流的可行性及可重复性。方法此项前瞻的非干预性研究共纳入了60例心脏手术患者,采用经食管心脏超声技术分别在体外循环前、中、后测定患者的左肾血流。取其中6例患者的超声图,由2位对实验毫不知情的独立评估者在图像采集当时及6个月后再次解读超声图。用变异性及组内相关系数定量计算同一研究者本身与不同研究者之间测量肾血流的可重复性。结果60倒患者中多普勒角度〉30°者（20例）被剔除,成功测量到36例患者的左肾血流。同一研究者与不同研究者的变异性均〈10％,可重复性为良好至极好（组内相关系数为0．604～0．999）,不同时间点（体外循环前、体外循环中和体外循环后）左肾动脉管腔直径为3．8～4．1mm,肾动脉血流速度为25—35cm／s,肾动脉血流量为192—299ml/min。结论在心脏手术患者中,有60％的病例可以通过经食管超声技术测量左肾血流,同一研究者和不同研究者测量肾脏血流的可重复性为良好至极好。     

Distal landing zone optimization before endovascular repair of aortic dissection

Background

The general goals of endovascular management in chronic distal thoracic aortic dissection are optimizing the true lumen, maintaining branch patency, and promoting false lumen (FL) thrombosis. Distal seal can be challenging in chronic distal thoracic aortic dissection due to the well-established secondary fenestrations and fibrotic septum. We describe our approach of distal landing zone optimization (DLZO) to enable full-diameter contact of the distal endoprosthesis.

Reliability analysis for radiographic measurement of limb length discrepancy: full-length standing anteroposterior radiograph versus scanogram

Patients with limb length discrepancy (LLD) often have associated angular deformities requiring a standing full-length radiograph of the lower limb in addition to a scanogram. The purpose of our study was to determine the intraobserver and interobserver reliability of measuring LLD with both techniques, using computed radiography. The LLD was measured on 70 supine scanograms and standing anteroposterior radiographs of the lower extremity by 5 blinded observers on 2 separate occasions. Intraclass correlation coefficient (ICC) and mean absolute difference (in millimeters) was calculated to assess intraobserver and interobserver reliability and found to be excellent for both radiographic techniques. Intraobserver ICC and mean absolute difference was 0.975 to 0.995 and 1.5 to 2.6 mm for scanogram and 0.939 to 0.996 and 1.5 to 4.6 mm for the standing radiograph, respectively. Repeated measurements for both radiographic studies were within 5 mm of the first measurement greater than 90% and within 10 mm greater than 95% of times. Interobserver ICC and mean absolute difference was 0.979 and 2.6 mm for scanogram and 0.968 and 3.0 mm for the standing radiograph. The reliability was excellent irrespective of age, sex, and underlying diagnosis other than Blount disease, which had good reliability. A standing anteroposterior radiograph of the lower extremity should be the imaging modality of choice when evaluating patients with limb length inequality who may have angular deformities because it allows a comprehensive evaluation of the extremity and is as reliable as a scanogram for measuring LLD. This approach may decrease the radiation exposure and financial burden involved in assessing patients with unequal limb lengths.     

The reliability of measurements of the lumbar spine using ultrasound B-scan

Diagnostic ultrasound is used in research and clinical settings to determine the size of the lumbar spinal canal. When the technique was first introduced, measurements were obtained directly from an A-scan while concurrently viewing a B-scan. However, measurements obtained directly from a B-scan are now commonly used despite the undetermined reliability of the technique. To determine the reliability, 50 randomly selected ultrasound B-scan examinations were read on two separate occasions by three investigators. For each spinal level, the mean intraobserver error (same investigator), from the first to the second reading was determined, as was the interobserver error (between investigators) and the error due to variability in obtaining the ultrasound images. The resultant errors were approximately double those reported previously for the technique using A-scan. Interobserver variations were the major source of measurement error.     

Four-dimensional flow cardiovascular magnetic resonance in aortic dissection: Assessment in an ex vivo model and preliminary clinical experience

Objective

Four-dimensional flow cardiovascular magnetic resonance may improve assessment of hemodynamics in patients with aortic dissection. The purpose of this study was to evaluate the feasibility and accuracy of 4-dimensional flow cardiovascular magnetic resonance assessment of true and false lumens flow.

Ultrasound imaging of infrainguinal arterial disease has a high interobserver agreement.

OBJECTIVES: to evaluate and compare the operator dependency of duplex ultrasound and digital subtraction arteriography (DSA) in patients suffering from chronic lower limb ischaemia. DESIGN: prospective and blinded validation study. MATERIAL: twenty-six consecutive patients (13 male and 13 females) with severe claudication (n=6, 23%), rest pain (n=7, 27%) or tissue loss (n=13, 50%). METHODS: two physicians independently performed a duplex scan of the lower limb from groin to foot (15 segments). Segments were classified as insignificantly (<50% stenosis) or significantly (>50% stenosis or occlusion) diseased. DSA was performed within 24h of the duplex scanning and was independently reported by two radiologists in the same manner. Interobserver agreement was assessed for both diagnostic methods. After 10 months the arteriograms were reassessed and the intraobserver agreement calculated. RESULTS: for the limb as a whole the interobserver agreement was good and similar for both duplex and DSA, with kappa-values of 0.79 (95%-CI: 0.72-0.86) and 0.80 (0.74-0.87). In the femoral, crural and pedal segments the interobserver agreement was similar for both methods. The intraobserver agreement between the two DSA readings was 0.84 (0.79-0.90). CONCLUSION: ultrasound is comparable to arteriography when visualising arterial occlusive disease in patients with chronic lower limb ischaemia.     

Predicting iliac limb occlusions after bifurcated aortic stent grafting: anatomic and device-related causes

OBJECTIVE: Graft limb occlusion may complicate endovascular abdominal aortic aneurysm repair. The precise etiologic factors that contribute to the development of these graft limb thromboses have not been defined. We evaluated our experience with bifurcated aortic endografts to determine factors that may predict subsequent limb thrombosis. The management of the thrombosed limbs and the results after treatment were also investigated. METHODS: During a 4-year period, 351 patients with aortic aneurysms underwent treatment with bifurcated endografts (702 graft limbs at risk). These 351 bifurcated devices included AneuRx (Medtronic, Minneapolis, Minn; n = 35), Ancure (Guidant, Menlo Park, Calif; n = 8), Gore (W.L. Gore & Associates, Sunnyvale, Calif; n = 25), Talent (World Medical, Sunrise, Fla; n = 255), Teramed (Teramed, Minneapolis, Minn; n = 10), and Vanguard (Boston Scientific Vascular, Natick, Mass; n = 18). Details regarding the type of device, mechanism of deployment, and aortoiliac artery anatomy were collected prospectively and analyzed. Graft limbs were analyzed for diameter, use of additional endograft iliac extensions, deployment in the external iliac artery, and endograft to vessel oversizing. Follow-up included physical examination, duplex ultrasonography, and spiral computed tomographic scans at 1 month, 6 months, and 12 months and annually thereafter. The follow-up period ranged from 2 to 54 months, with a mean follow-up period of 20 months. RESULTS: Twenty-six of 702 limbs (3.7%) had an occlusion develop. The risk of limb thrombosis was associated with a smaller limb diameter. Mean graft limb diameter was 14 mm in the occluded population, and patent limbs had a mean diameter of 16 mm. Thrombosis occurred in 16 of 291 limbs (5.5%) that were 14 mm or less and in 10 of 411 limbs (2.4%) that were greater than 14 mm (P =.03). Extension of a graft to the external iliac artery was performed in 96 of the 702 limbs. Eight of these 96 limbs (8.3%) had thrombosis develop as compared with 18 of 606 (3.0%) that extended to the common iliac artery (P =.01). No significant association was present between limb thrombosis and the contralateral or ipsilateral side of a device, the configuration of the iliac graft limb end (closed web, open web, or bare spring), or the degree of iliac graft limb oversizing. AneuRx, Ancure, Vanguard, and Talent grafts each sustained limb occlusions, with no occlusions seen among the Gore and Teramed devices. No significant increased risk of graft limb thrombosis was observed in unsupported grafts (1/16; 6.3%) versus supported grafts (25/686; 3.6%; P = not significant). Thromboses occurred between 1 day and 23 months after surgery. Thirteen of the 26 thromboses (50%) occurred within 30 days of surgery. Presenting symptoms were mild to moderate claudication in eight patients (30.8%), severe claudication in 16 patient (61.5%), and paresthesia and rest pain in two patients (7.7%). Eighteen of 26 patients (69.2%) eventually needed intervention to reestablish flow to the occluded limb, including thrombolysis and stenting in two patients (7.7%), axillary femoral bypass in one patient (3.8%), femoral-femoral bypass in 13 patients (50.0%), and axillary-bifemoral bypass in two patients (7.7%). All patients with mild to moderate symptoms under observation had improvement in symptoms with no further interventions necessary. All revascularizations were successful in relieving symptoms. CONCLUSION: Graft limb occlusion is a recognized complication of endovascular treatment of abdominal aortic aneurysms that may be associated with smaller graft limb diameter and extension to the external iliac artery. Occlusions usually necessitate additional intervention for resolution of ischemic symptoms. The use of small diameter grafts should be avoided when possible to reduce the risk of graft limb occlusions.