Endovascular Aneurysm Repair Planning Research Articles

Towards a reduced order model for EVAR planning and intra-operative navigation

IntroductionThe pre-operative planning and intra-operative navigation of the endovascular aneurysm repair (EVAR) procedure are currently challenged by the aortic deformations that occur due to the insertion of a stiff guidewire. Hence, a fast and accurate predictive tool may help clinicians in the decision-making process and during surgical navigation, potentially reducing the radiations and contrast dose. To this aim, we generated a reduced order model (ROM) trained on parametric finite element simulations of the aortic wall-guidewire interaction. MethodA Design of Experiments (DOE) consisting of 300 scenarios was created spanning over seven parameters. Radial basis functions were used to achieve a morphological parametrization of the aortic geometry. The ROM was built using 200 scenarios for training and the remaining 100 for validation. ResultsThe developed ROM estimated the displacement of aortic nodes with a relative error below 5.5% for all the considered validation cases. From a preliminary analysis, the aortic elasticity, the stiffness of the guidewire and the tortuosity of the cannulated iliac artery proved to be the most influential parameters. ConclusionsOnce built, the ROM provided almost real-time and accurate estimations of the guidewire-induced aortic displacement field, thus potentially being a promising pre- and intra-operative tool for clinicians.

Comparison of Three Workstations For Abdominal Aortic Aneurysm Sizing: Impact in Decision Making and Graft Selection

Purpose: The aim of this study was to assess the agreement of multiplanar reconstruction (MPR) and semiautomated central lumen line (CLL) analysis of abdominal aortic aneurysms (AAA), with 3 different software workstations (WS1, WS2, WS3) and 2 experienced practitioners as well as to analyze its eventual impact in graft selection. Materials and methods: Twenty computed tomography (CT) angiography data sets were randomly chosen from a series of 100 consecutive studies. Measurements were performed twice by each reader, in random order, and included 8 parameters (5 diameters and 3 lengths). Each observer performed a complete set of 60 studies. Intra-observer and interobserver variability for every WS was assessed. Measurements were evaluated using Bland-Altman analysis, correlation coefficients (r), and concordance correlation coefficients (CCC [95% confidence interval (CI)]). Results: A high overall agreement between repeated measurements for both observers was obtained (r=0.989; CCC=0.988 [0.982–0.992] and r=0.998; CCC=0.996 [0.994–0.997], for observers 1 and 2, respectively). However, reproducibility for individual parameters was excellent for observer 2 and only moderate for observer 1. A high overall agreement was obtained for interobserver concordance (r=0.987; CCC=0.986 [0.982–0.989]). When analyzing for individual parameters, greatest interobserver differences were found at CLL measurement of the diameter of aortic neck (WS2) and bifurcation (WS1 and WS2) as well as iliac diameter in all 3 WS for both CLL and MPR. Similar differences were observed in paired comparison between WS when involving these parameters. Careful inspection of Bland-Altman charts revealed some cases of disagreement between WS and observers that would affect decision making on graft selection, changing the neck diameter to a different size, in 2 cases when measuring with WS1, and iliac diameter in 4 cases (2 of them with WS1 and 2 with WS2). Greatest discordance was observed regarding ipsilateral iliac length affecting 7 measurements that would lead to change the length of the selected limb graft (2 with WS1, 3 with WS2, and 2 with WS3). Conclusions: Although a high agreement between different observers using different WS for AAA measurements is to be expected, small differences may lead to the selection of a different graft size. The use of a single software by experienced users, and double check by a different one, may be advisable. Clinical Impact Influence of inter and intraobserver variability in CT measurements during planning of endovascular aneurysm repair (EVAR) has been extensively reviewed. However, its impact in graft selection (final choose of diameter and lengths) has been scarcely analyzed. The results of this study suggest that, although a high agreement between different observers using different workstations for AAA measurements is to be expected, small differences may lead to the selection of a different graft size. The use of a single software by experienced users, and double check by a different one, may be advisable.

Prevalence of Erectile Dysfunction in Patients With Abdominal Aortic Aneurysm: An Exploratory Study.

IntroductionErectile dysfunction (ED) is defined as the recurrent inability to achieve and maintain a satisfactory erection for sexual intercourse. Many studies have highlighted that ED shares common cardiovascular risk factors with cardiovascular disease. No data are reported about the prevalence of ED in patients with the abdominal aortic aneurysm (AAA). The aim of our study was to investigate the preoperative information given about sexual functions of patients undergoing endovascular aneurysm repair (EVAR) and to compare it with the presence and severity of steno-occlusive atherosclerotic lesions of the pelvic arterial tree at pre-operative Computed Tomography Angiography (CTA).MethodsWe prospectively enrolled all men patients who underwent elective EVAR from September to November 2021. Preoperative ED was evaluated using the International Index of Erectile Function (IIEF-5) questionnaire. Preoperative imaging was routinely performed with CTA scan of the abdominal aorta and iliac-pelvic district. An innovative score of pelvic arterial disease associated to AAA was defined, dividing the iliac district in 4 zones attributing a grading of severity for each zone bilaterally (score ranges 0–24). Linear regression analysis was used to correlate IIEF-5 score to anatomical score of pelvic arterial steno-occlusive disease.ResultsA total of 25 patients were enrolled. Median age was 74 ± 5.3 years. IIEF-5 average score was 14.8 ± 7.1. Eight cases (32%) had severe ED; one case (4%) had moderate, five patients (20%) had mild to moderate ED; five patients (20%) had mild ED, and 6 (24%) patients had no ED. CTA evaluation revealed an average anatomical score of 7.9 ± 4.5. Pelvic disease was considered moderate-severe in 20 cases (80%) and not significant in 20% (five cases). Linear regression analysis confirmed the hypothesis that a more diseased pelvic arterial tree was correlated to a more severe ED (Y = −1.531* × + 26.35 [slope CI: −1.946 to −1.117, p < 0.0001]).ConclusionAlthough typically unreported, the prevalence of ED associated to AAA was found to be high. A vasculogenic origin of ED in patients with AAA is plausible and may be easily confirmed by the evaluation of pelvic arterial distribution at angio-CT performed for EVAR planning. Our proposed “MAPPING AND SCORING SHEET” may help to identify the vasculogenic origin of ED in AAA patients.

Significance of preoperative thrombus burden in the prediction of a persistent type II and reintervention after infrarenal endovascular aneurysm repair

BackgroundPersistent type II endoleak has necessitated prolonged surveillance and is a reason for reintervention after infrarenal endovascular aneurysm repair (EVAR). The aim of this study was to assess the association of thrombus burden (TB) within the aneurysmal sac in the prediction of a persistent type II endoleaks. MethodsConsecutive patients who underwent infrarenal EVAR from October 2009 to October 2017 in a single vascular network were included. TB was assessed on preoperative computed tomography angiogram and was defined as a percentage of thrombus across the maximal sac diameter in comparison with the luminal diameter measured orthogonally at the same level. Patients were categorized into three groups: low TB (<25%), medium TB (25%-50%), and high TB (>50%). All patients underwent postoperative EVAR surveillance comprising computed tomographic angiography or duplex ultrasound imaging. Type II endoleak observed for more than 1 year was defined as persistent type II endoleak. Odds ratio (OR) and Student’s t-test were used to determine significance. ResultsSome 275 EVARs were performed in the study period. A total of 45 procedures were excluded because of either iliac-only intervention (n = 9), no preoperative information (n = 7), abandoned (n = 1), or less than 1 year’s follow-up data (n = 28). For the 230 procedures included, the median follow-up was 43 (12-102) months. There were no significant differences between the groups for age, gender, and comorbidities nor preoperative sac diameter. There was high interobserver reliability with a kappa value of 0.89 (0.84-0.94) with a total discordance of 7% across the cohorts. Persistent type II endoleak occurred significantly more frequently with reduced TB: 41% of the low TB cohort compared with 4% of the high TB cohort (OR, 15.36 [3.5-67.3]; P = .0003). Reintervention was also significantly more likely to occur in the presence of a persistent type II endoleak compared with its absence; n = 12 of 13 (92%) patients who underwent reintervention had a persistent type II endoleak (OR, 43.4 [5.5-242]; P = .0003). Sac size reduction was significantly greater in medium TB and high TB cohorts when compared with low TB: −25% and −27% vs −15% (P = .0046 and P < .0001). Decreased TB was associated with a significant increase in inferior mesenteric artery (IMA) patency, the mean TB, where the IMA was patent, being 29% compared with 40% where the IMA was occluded P < .0001. When considered together, patients with a low TB and a patent IMA were even more likely to have a persistent type II endoleak when compared with those with a high TB and an occluded IMA (OR, 34.1 [1.99-583]; P = .015). ConclusionsLow TB is associated with increased rates of persistent type II endoleak, especially in the presence of a patent IMA. High TB is associated with increased sac regression and low reintervention rates. TB can be assessed reliably and could be used for risk stratification in the planning of infrarenal EVAR. Pre-emptive embolization of IMA or lumbar vessels in those with low TB may be beneficial. TB could be a useful tool for designing a post-EVAR surveillance regimen.

EVAR-eaSE: An Easy-to-Use Software for Planning Sac Embolization in EndoVascular Aneurysm Repair Procedure

Background: Endovascular aneurysm repair (EVAR) has become the primary choice of treatment for abdominal aortic aneurysm (AAA) and preventive intraoperative AAA sac embolization (SE) is an effective way to reduce endoleaks after EVAR. Preoperative planning of AAA SE has not been standardized yet, and typically requires a quite long and operator-dependent procedure using standard EVAR planning software. Methods: We introduce ‘EVAR-eaSE’, a software tool that we have developed to help vascular surgeons to plan the optimal SE procedure during EVAR, providing semi-automatic AAA segmentation and 3D modeling starting from patient scans, and then computing the aneurysm volumes. A preliminary accuracy evaluation on radiological phantoms, and a comparison with the commercial 3Mensio software for EVAR planning are carried out. Results: EVAR-eaSE software showed a good level of accuracy in aneurysm volume reconstruction and calculation (mean difference of 2.5% between real and segmented phantom volumes). A strong positive correlation (r = 0.940, r = 0.954, p &lt; 0.001) was found between EVAR-eaSE computation of AAA Lumen and AAA Total volumes and the same measurements obtained with 3Mensio, for a database of 26 AAA cases. Conclusions: EVAR-eaSE demonstrated to be an easy-to-use, objective and accurate tool to assist the vascular surgeons in preoperative planning of SE during EVAR.

Stent Graft Sizing for Endovascular Abdominal Aneurysm Repair Using Open Source Image Processing Software

An important step to reach a favorable outcome of abdominal endovascular aneurysm repair (EVAR) is preoperative sizing of the stent graft using computed tomography angiography (CTA) images of the abdominal aorta. A variety of costly image processing software options is available to obtain the necessary aortic measurements. A package that can be used for EVAR sizing is OsiriX Lite®-an open source, freely downloadable image processing option. This study assesses the concurrent validity of OsiriX Lite® when compared with commercially available 3Mensio Vascular® and Siemens Syngo.via®. CTA scans of 20 patients that underwent EVAR for abdominal aneurysm were selected, 10 elective and 10 ruptured. For each scan, 6 observers determined 20 parameters needed for proper stent graft sizing, 2 using Osirix Lite®, 3 using 3Mensio Vascular®, and 1 using Siemens Syngo.via®. For each parameter, an intraclass correlation coefficient (ICC) and a P-value were calculated. Interrater agreement was interpreted using the Koo and Li Guidelines. Time needed to perform EVAR planning was compared. Overall interrater agreement between the 3 sizing options was found to be either "good" or "moderate" for 16 out of 20 parameters (80%). Time needed to perform EVAR planning was not significantly different for Osirix Lite® (568sec) when compared with 3Mensio Vascular® (603sec) or Siemens Syngo.via® (659sec) with a P-value of 0.88. The authors conclude that Osirix Lite® is an accurate and time-effective image processing option for preoperative sizing of an EVAR stent graft when matched to 3Mensio Vascular® and Siemens Syngo.via®.

Abstract No. 489 Ultralow contrast dose using catheter-directed computed tomography angiography in patients with renal insufficiency

CT angiography offers excellent anatomic detail necessary for vascular procedural planning including endovascular aneurysm repair (EVAR). However, patients with renal insufficiency are at risk for acute renal failure due to iodinated contrast administration. Catheter-directed CT angiography is a technique in which dilute iodinated contrast is injected into an intra-aortic pigtail catheter during the CT scan. The purpose of this study was to evaluate the safety and efficacy of this technique. Retrospective review of patients with renal insufficiency (GFR<30) who underwent catheter-directed CT angiography for one of the following indications: preoperative EVAR planning, evaluation of arterial occlusive disease or endoleak evaluation following EVAR. A pigtail catheter was advanced into the aorta using standard angiographic technique. In the CT scanner, the pigtail catheter was injected with one third diluted contrast (20 mL iodinated contrast with 40 mL saline) at a rate of 6 mL/s for a total of 60 mL. A 6 second CT scanner delay was utilized. Technical success, complications, pre and post creatinine and GFR, Hounsfield units (HU) attained in the aorta were recorded. Values > 150 HU were considered sufficient. Subjective image assessment was performed by 2 observers to assess clinical adequacy for procedural planning. From 2015-2019, 11 patients, mean age 74, 9M:2F, underwent catheter-directed CT angiography. The mean contrast usage was 23 mL. There were no complications and a 100% technical success. The preoperative baseline Cr and GFR was 2.9 ± 0.7 and 22 ± 6. The post procedure Cr and GFR were 2.9 ± 0.7 and 22 ± 7. There were no cases of acute renal failure. The mean HU in the aorta was 397 ± 294. Subjective assessment showed all studies to be clinically adequate for their respective indications. Catheter-directed CT angiography is a safe and effective technique for obtaining contrast-enhanced vascular studies in patients with renal insufficiency using an ultralow contrast dose.

A Methodology to Quantify the Geometrical Complexity of the Abdominal Aortic Aneurysm

The abdominal aortic aneurysm (AAA) anatomy influences the technical success of the endovascular aneurysm repair (EVAR), yet very few data regarding the aortic tree angles exist in the literature. This poses great limitations in the numerical analyses of endografts, constraining their design improvement as well as the identification of their operational limitations. In this study, a matrix Φ of 10 angles was constructed for the description of the pathological region and was implemented on a large dataset of anatomies. More specifically, computed tomography angiographies from 258 patients were analysed and 10 aortic angles were calculated per case, able to adequately describe the overall AAA shape. 9 dimensional variables (i.e. diameters and lengths) were also recorded. The median and extreme values of these variables were computed providing a detailed quantification of the geometrical landscape of the AAA. Moreover, statistical analysis showed that the identified angles presented no strong correlation with each other while no lateral or anterior/posterior symmetry of the AAA was identified. These findings suggest that endograft designers are free to construct any extreme case-studies with the values provided in a mix-and-match manner. This strategy can have a powerful effect in EVAR stent graft designing, as well as EVAR planning.

Patient-specific in silico endovascular repair of abdominal aortic aneurysms: application and validation.

Non-negligible postinterventional complication rates after endovascular aneurysm repair (EVAR) leave room for further improvements. Since the potential success of EVAR depends on various patient-specific factors, such as the complexity of the vessel geometry and the physiological state of the vessel, in silico models can be a valuable tool in the preinterventional planning phase. A suitable in silico EVAR methodology applied to patient-specific cases can be used to predict stent-graft (SG)-related complications, such as SG migration, endoleaks or tissue remodeling-induced aortic neck dilatation and to improve the selection and sizing process of SGs. In this contribution, we apply an in silico EVAR methodology that predicts the final state of the deployed SG after intervention to three clinical cases. A novel qualitative and quantitative validation methodology, that is based on a comparison between in silico results and postinterventional CT data, is presented. The validation methodology compares average stent diameters pseudo-continuously along the total length of the deployed SG. The validation of the in silico results shows very good agreement proving the potential of using in silico approaches in the preinterventional planning of EVAR. We consider models of bifurcated, marketed SGs as well as sophisticated models of patient-specific vessels that include intraluminal thrombus, calcifications and an anisotropic model for the vessel wall. We exemplarily show the additional benefit and applicability of in silico EVAR approaches to clinical cases by evaluating mechanical quantities with the potential to assess the quality of SG fixation and sealing such as contact tractions between SG and vessel as well as SG-induced tissue overstresses.

Repair of abdominal aortic aneurysms: preoperative imaging and evaluation.

Imaging is a critical component of the pre-procedure evaluation and planning of endovascular aneurysm repair (EVAR). Imaging is the mainstay for proper assessment of procedural candidacy, relevant vascular anatomy, device selection, and surgical approach. Computed tomography angiography (CTA) has long been considered the preferred modality for pre-operative imaging and evaluation prior to EVAR. Recently, advances in image quality and software technology have further enhanced the proceduralist's ability to plan and perform EVAR. In this review, we highlight the current state of the art to provide interventionalists a contemporary assessment of the available tools for pre-operative imaging and evaluation prior to EVAR.

On the optimization of low-cost FDM 3D printers for accurate replication of patient-specific abdominal aortic aneurysm geometry

BackgroundThere is a potential for direct model manufacturing of abdominal aortic aneurysm (AAA) using 3D printing technique for generating flexible semi-transparent prototypes. A patient-specific AAA model was manufactured using fused deposition modelling (FDM) 3D printing technology. A flexible, semi-transparent thermoplastic polyurethane (TPU), called Cheetah Water (produced by Ninjatek, USA), was used as the flexible, transparent material for model manufacture with a hydrophilic support structure 3D printed with polyvinyl alcohol (PVA). Printing parameters were investigated to evaluate their effect on 3D–printing precision and transparency of the final model. ISO standard tear resistance tests were carried out on Ninjatek Cheetah specimens for a comparison of tear strength with silicone rubbers.ResultsIt was found that an increase in printing speed decreased printing accuracy, whilst using an infill percentage of 100% and printing nozzle temperature of 255 °C produced the most transparent results. The model had fair transparency, allowing external inspection of model inserts such as stent grafts, and good flexibility with an overall discrepancy between CAD and physical model average wall thicknesses of 0.05 mm (2.5% thicker than the CAD model). The tear resistance test found Ninjatek Cheetah TPU to have an average tear resistance of 83 kN/m, higher than any of the silicone rubbers used in previous AAA model manufacture. The model had lower cost (4.50 GBP per model), shorter manufacturing time (25 h 3 min) and an acceptable level of accuracy (2.61% error) compared to other methods.ConclusionsIt was concluded that the model would be of use in endovascular aneurysm repair planning and education, particularly for practicing placement of hooked or barbed stents, due to the model’s balance of flexibility, transparency, robustness and cost-effectiveness.

Standard and fenestrated endograft sizing in EVAR planning: Description and validation of a semi-automated 3D software

An abdominal aortic aneurysm (AAA) is a pathological dilation of the abdominal aorta that may lead to a rupture with fatal consequences. Endovascular aneurysm repair (EVAR) is a minimally invasive surgical procedure consisting of the deployment and fixation of a stent–graft that isolates the damaged vessel wall from blood circulation. The technique requires adequate endovascular device sizing, which may be performed by vascular analysis and quantification on Computerized Tomography Angiography (CTA) scans. This paper presents a novel 3D CTA image-based software for AAA inspection and EVAR sizing, eVida Vascular, which allows fast and accurate 3D endograft sizing for standard and fenestrated endografts. We provide a description of the system and its innovations, including the underlying vascular image analysis and visualization technology, functional modules and user interaction. Furthermore, an experimental validation of the tool is described, assessing the degree of agreement with a commercial, clinically validated software, when comparing measurements obtained for standard endograft sizing in a group of 14 patients.

The Benefits of EVAR Planning Using a 3D Workstation

To evaluate the influence of planning endovascular aneurysm repair (EVAR) with a three-dimensional (3D) workstation on early and midterm outcomes. All patients undergoing infrarenal EVAR performed between 2006 and 2009 at our institution were included in the current study. Prior to 2008 (group 1), endograft sizing was performed by interrogation of computed tomography angiography axial images. After 2008 (group 2), endograft sizing was routinely performed using a 3D workstation (Aquarius, Terarecon), allowing for multiplanar reconstruction and centerline analysis. Pre-, peri-, postoperative, and follow-up data were prospectively entered in an electronic database. All postoperative complications and subsequent secondary interventions depicted during the 2-year period following EVAR were compared. Secondary intervention and mortality rates were defined at 2 years and compared. Freedom from secondary intervention and overall survival rates were calculated using the Kaplan-Meier method during follow-up and compared by log-rank test. A total of 295 patients (149 patients in group 1 and 146 patients in group 2) were included. All patients had completed a minimum of 2 years of follow-up. During this 2-year period following EVAR, the type 1 endoleak rate was 8.7% in group 1 and 1.4% in group 2 (P = .004) respectively. Secondary intervention rates related to type 1 endoleak was 5.4% in group 1 and 0 in group 2 (P < .001). No difference was observed regarding all-cause mortality, aneurysm-related death, and freedom from secondary intervention rates during follow-up. The routine use of 3D workstations for EVAR planning significantly reduces the rate of type 1 endoleaks and, therefore, the rate of related secondary interventions.

The Benefits of EVAR Planning Using a 3D Workstation

To evaluate the influence of planning endovascular aneurysm repair (EVAR) with a three-dimensional (3D) workstation on early and midterm outcomes. All patients undergoing infrarenal EVAR performed between 2006 and 2009 at our institution were included in the current study. Prior to 2008 (group 1), endograft sizing was performed by interrogation of computed tomography angiography axial images. After 2008 (group 2), endograft sizing was routinely performed using a 3D workstation (Aquarius, Terarecon), allowing for multiplanar reconstruction and centerline analysis. Pre-, peri-, postoperative, and follow-up data were prospectively entered in an electronic database. All postoperative complications and subsequent secondary interventions depicted during the 2-year period following EVAR were compared. Secondary intervention and mortality rates were defined at 2 years and compared. Freedom from secondary intervention and overall survival rates were calculated using the Kaplan-Meier method during follow-up and compared by log-rank test. A total of 295 patients (149 patients in group 1 and 146 patients in group 2) were included. All patients had completed a minimum of 2 years of follow-up. During this 2-year period following EVAR, the type 1 endoleak rate was 8.7% in group 1 and 1.4% in group 2 (p = .004) respectively. Secondary intervention rates related to type 1 endoleak was 5.4% in group 1 and 0 in group 2 (p < .001). No difference was observed regarding all-cause mortality, aneurysm-related death, and freedom from secondary intervention rates during follow-up. The routine use of 3D workstations for EVAR planning significantly reduces the rate of type 1 endoleaks and, therefore, the rate of related secondary interventions.

Preoperative Planning for Endovascular Aortic Repair of Abdominal Aortic Aneurysms: Feasibility of Nonenhanced MR Angiography versus Contrast-enhanced CT Angiography

To compare vascular measurements to determine stent types and configurations for abdominal endovascular aneurysm repair (EVAR) by comparing results of contrast material-enhanced computed tomographic (CT) angiography and nonenhanced magnetic resonance (MR) angiography. This prospective study was institutional review board approved, and all patients provided written informed consent. Fifty patients (45 men and five women; mean age, 76.0 years) admitted for elective abdominal EVAR underwent preoperative abdominal CT angiography (triplanar reformatted images; section thickness of 1-3 mm) and nonenhanced MR angiography (triplanar two-dimensional single-shot turbo field-echo images; section thickness of 6 mm). Two observers independently completed standard measurement and device selection forms for endovascular stent planning for CT and MR angiography. Pearson and intraclass correlation coefficients were calculated to evaluate intermodality and interobserver differences. No significant difference was found in aortic neck diameter (observer 1: CT, 18.5 mm; MR, 19.0 mm; P = .43) (observer 2: CT, 19.6 mm; MR, 19.3 mm; P = .59), aortic neck diameter 15 mm distal to the lowest renal artery (observer 1: CT, 19.2 mm; MR, 19.2 mm; P = .38) (observer 2: CT, 19.6 mm; MR, 19.6 mm; P = .91), aortic neck length (observer 1: CT, 43.6 mm; MR, 43.6 mm; P = .85) (observer 2: CT, 44.4 mm; MR, 44.0 mm; P = .93), or other key vascular measurements (P = .23-.99) for preoperative planning. These included aneurysm diameter, lowest renal artery to aortic bifurcation length, aortic bifurcation diameter, common iliac artery diameters, external iliac artery diameters, length between orifices of lower renal and internal iliac arteries, and iliac artery sealing length. CT and MR angiography measurements showed very strong correlation (r = 0.92-0.99). Intraclass correlation coefficients between observers ranged from 0.90 to 0.98. Stent types and configurations determined with CT measurements remained unaltered when reassessed with MR measurements. Measurements obtained with nonenhanced MR angiography appear equally accurate to those of CT angiography in the preoperative planning of abdominal EVAR.

Limb occlusion after endovascular repair of an abdominal aortic aneurysm: beware the narrow distal aorta

This case aims to highlight the need for careful scrutiny of the distal aorta during endovascular aneurysm repair (EVAR) planning to avoid potentially avoidable graft limb occlusion. We present a case of graft limb occlusion after EVAR, unresponsive to endovascular re-intervention requiring surgical extra-anatomic revascularization, due to a narrow distal aorta causing graft impingement and collapse. We suggest clinicians should be aware of this potential pitfall during EVAR planning and beware the narrow distal aorta.

Intravascular ultrasound with a vector phased-array probe (acunav) is feasible in endovascular abdominal aortic aneurysm repair

The ideal imaging method for endovascular aneurysm repair (EVAR) should provide all data regarding diagnosis, measurements, and guiding of stent-graft deployment. Contrast-enhanced computed tomography (CT) is used for preoperative EVAR planning, together with intraoperative angiography. However, the administered contrast volume might result in contrast-induced nephropathy (CIN). To develop a technique for aortic measurements, vessel wall evaluation, and stent-graft positioning by using a vector phased-array intravascular ultrasound probe with color Doppler function (AcuNav) in elective EVAR. Thirteen elective EVAR patients were included. AcuNav was compared to pre- and postoperative CT examinations, perioperative angiography, and postoperative duplex. Measurements for stent-graft sizing were easily obtained and facilitated by the color Doppler function and corresponded well with CT and angiography. The combined information from AcuNav and fluoroscopy provided exact positioning of the stent graft. An aortic placement of the probe provided superior imaging results compared to an inferior vena cava approach. Detection of endoleak was found to be difficult. No complications were registered. The use of AcuNav combined with fluoroscopy in EVAR was found to be safe, effective, and feasible in planning and guiding EVAR procedures. Best results were seen with the probe placed in the artery. AcuNav might be used to replace contrast-enhanced CT and angiography, hence reducing the risk of CIN, especially in high-risk patients.

Impact of 3-Dimensional-Computed Tomography Workstation for Precise Planning of Endovascular Aneurysm Repair

Compared with open surgery, imaging is considered to be important for planning and device selection of endovascular aneurysm repair (EVAR). The present study evaluated the usefulness of a 3-dimensional (3D)-computed tomography (CT) workstation in planning EVAR. A prospective study was conducted in 8 patients who underwent EVAR using Zenith endograft between February and August 2007. Endograft size and optimized deployment projection were decided using a 3D-CT workstation. The primary endpoint was defined as successful deployment of a same size endograft as preoperatively selected without type I or III endoleak or inadvertent arterial occlusion. The following parameters were investigated: (a) incidence of use of an alternative endograft; (b) prevalence of type I or III endoleak; and (c) distance from lowest renal artery to tip of graft. Successful deployment of endograft was achieved in all 8 patients. Use of alternative endograft or type I or III endoleak was not detected in 8 patients. Distance from the lowest renal artery to the tip of the graft was 2.8mm. Assessment using a 3D-CT workstation appears to allow accurate endograft selection and precise deployment of the Zenith endograft without type I or III endoleak, even in institutes with a small number of patients.