Use of Numerical Simulation to Predict Iliac Complications During Placement of An Aortic Stent Graft.

BACKGROUND: During endovascular aneurysm repair (EVAR), complex iliac anatomy is a source of complications such as unintentional coverage of the hypogastric artery. The aim of our study was to evaluate ability to predict coverage of the hypogastric artery using a biomechanical model simulating arterial deformations caused by the delivery system. METHODS: The biomechanical model of deformation has been validated by many publications. The simulations were performed on 38 patients included retrospectively, for a total of 75 iliac arteries used for the study. On the basis of objective measurements, two groups were formed: one with "complex" iliac anatomy (n = 38 iliac arteries) and the other with "simple" iliac anatomy (n = 37 iliac arteries). The simulation enabled measurement of the lengths of the aorta and the iliac arteries once deformed by the device. Coverage of the hypogastric artery was predicted if the deformed renal/iliac bifurcation length (Lpre) was less than the length of the implanted device (Lstent-measured on the postoperative computed tomography [CT]) and nondeformed Lpre was greater than Lstent. RESULTS: Nine (12%) internal iliac arteries were covered unintentionally. Of the coverage attributed to perioperative deformations, 1 case (1.3%) occurred with simple anatomy and 6 (8.0%) with complex anatomy (P = 0.25). All cases of unintentional coverage were predicted by the simulation. The simulation predicted hypogastric coverage in 35 cases (46.7%). There were therefore 26 (34.6%) false positives. The simulation had a sensitivity of 100% and a specificity of 60.6%. On multivariate analysis, the factors significantly predictive of coverage were the iliac tortuosity index (P = 0.02) and the predicted margin between the termination of the graft limb and the origin of the hypogastric artery in nondeformed (P = 0.009) and deformed (P = 0.001) anatomy. CONCLUSIONS: Numerical simulation is a sensitive tool for predicting the risk of hypogastric coverage during EVAR and allows more precise preoperative sizing. Its specificity is liable to be improved by using a larger cohort.

Fusion Imaging for EVAR with Mobile C-arm.

BACKGROUND: Fusion imaging is a technique that facilitates endovascular navigation but is only available in hybrid rooms. The goal of this study was to evaluate the feasibility of fusion imaging with a mobile C-arm in a conventional operating room through the use of an angionavigation station. METHODS: From May 2016 to June 2017, the study included all patients who underwent an aortic stent graft procedure in a conventional operating room with a mobile flat-panel detector (Cios Alpha, Siemens) connected to an angionavigation station (EndoNaut, Therenva). The intention was to perform preoperative 3D computerized tomography/perioperative 2D fluoroscopy fusion imaging using an automatic registration process. Registration was considered successful when the software was able to correctly overlay preoperative 3D vascular structures onto the fluoroscopy image. For EVAR, contrast dose, operation time, and fluoroscopy time (FT) were compared with those of a control group drawn from the department's database who underwent a procedure with a C-arm image intensifier. RESULTS: The study included 54 patients, and the procedures performed were 49 EVAR, 2 TEVAR, 2 IBD, and 1 FEVAR. Of the 178 registrations that were initialized, it was possible to use the fusion imaging in 170 cases, that is, a 95.5% success rate. In the EVAR comparison, there were no difference with the control group (n = 103) for FT (21.9 ± 12 vs. 19.5 ± 13 min; P = 0.27), but less contrast agent was used in the group undergoing a procedure with the angionavigation station (42.3 ± 22 mL vs. 81.2 ± 48 mL; P < 0.001), and operation time was shorter (114 ± 44 vs. 140.8 ± 38 min; P < 0.0001). CONCLUSIONS: Fusion imaging is feasible with a mobile C-arm in a conventional operating room and thus represents an alternative to hybrid rooms. Its clinical benefits should be evaluated in a randomized series, but our study already suggests that EVAR procedures might be facilitated with an angionavigation system.

Influencing factors of sac shrinkage after endovascular aneurysm repair.

OBJECTIVE: Sac shrinkage is considered a reliable surrogate marker of success after endovascular aneurysm repair (EVAR). Whereas sac shrinkage is the best expected outcome, predictive factors of sac shrinkage remain unclear. The aim of this study was to identify the role of preoperative and postoperative influencing factors of sac reduction after EVAR. METHODS: Online searches across MEDLINE, Embase, and Cochrane Library medical databases were simultaneously performed. Study effects were pooled using a random-effects model, and forest plots were generated for every potential influencing factor. RESULTS: A total of 24 studies with 14,754 patients were included (mean age, 73.4 years; 76% male). At a mean follow-up of 24 months, the pooled shrinkage proportion was 47%. Random-effects meta-analysis revealed that renal impairment (odds ratio [OR], 0.74; 95% confidence interval [CI], 0.57-0.96), type I endoleaks (OR, 0.17; 95% CI, 0.08-0.39), type II endoleaks (OR, 0.21; 95% CI, 0.14-0.33), and combined type I and type II endoleaks (OR, 0.32; 95% CI, 0.22-0.47) were found to prevent sac shrinkage, whereas hypercholesterolemia (OR, 1.24; 95% CI, 1.02-1.51) and smoking (OR, 1.32; 95% CI, 1.17-1.49) have a significant positive impact on sac shrinkage. In addition, there was a trend toward the association between shrinkage and statin therapy (OR, 4.07; 95% CI, 1.02-16.32) and nearly significant negative impacts of coronary artery disease (OR, 0.84; 95% CI, 0.70-1.01), diabetes (OR, 0.79; 95% CI, 0.60-1.04), and sac thrombus (OR, 0.88; 95% CI, 0.77-1.01) on sac shrinkage. CONCLUSIONS: In this large meta-analysis of patients undergoing EVAR, we found that several comorbidity and postoperative factors were associated with postoperative sac shrinkage. These findings may contribute to a better understanding of the shrinkage process of patients undergoing EVAR.

Predictive Models of Complications after Endovascular Aortic Aneurysm Repair.

BACKGROUND: The risk of long-term complications after endovascular aneurysm repair (EVAR) is still higher than open surgery and is a critical issue. This study aims to make available reliable statistical predictive models of complications after EVAR. METHODS: Two hundred and thirteen patients who underwent EVAR between 2002 and 2012 were included in this study. The preoperative computed tomography scans were analyzed with a dedicated workstation to provide spatially correct 3-dimensional data. Age, gender, operation-related factors, and 21 morphologic variables were measured and included in the analyses. Five postoperative outcomes were studied. After an initial selection of predictors based on univariate analysis, binomial logistic regression models were proposed for each outcome. The ability to predict each outcome was assessed with receiver operating characteristic curves considering that an area under the curve (AUC) > 0.70 is generally considered sufficiently accurate. RESULTS: The mean age was 74.8 ± 8.6 years with a mean follow-up of 43.8 ± 22.1 months. Respectively, rates and risk factors of each outcome were 25.3% (n = 51) for abdominal aortic aneurysm (AAA) enlargement (age, number of patent sac branches, iliac calcifications and tortuosity, aneurysmal thrombus), 7% (n = 15) for type IA endoleak (neck calcification and AAA diameter), 3.7% (n = 8) for type IB endoleak (iliac tortuosity, AAA diameter, neck thrombus), 19.8% (n = 40) for type II endoleak (female, number of patent sac branches), and 25.9% (n = 55) for reintervention from any cause (neck calcification). The risk associated to each outcome can be calculated with a combination of these different preoperative variables. AUC for each outcome were 79.6% for AAA enlargement, 70.4% for reintervention, 81.3% for type IA endoleak, 92.3% for type IB endoleak, 70.6% for type II endoleak. CONCLUSIONS: This study shows that an exhaustive description of the preoperative anatomy before EVAR is a powerful and reliable tool to predict the risk of developing the most common complications after EVAR.

Evaluation by Magnetic Resonance Imaging of Silent Brain Infarcts in Preoperative and Postoperative Asymptomatic Carotid Surgery.

BACKGROUND: To report the prevalence of silent brain infarcts (SBI) at magnetic resonance imaging (MRI) before and after surgery for asymptomatic high grade carotid stenosis. METHODS: This is a single center retrospective observational study. Asymptomatic patients who underwent carotid endarterectomy between October 2012 and October 2014 were included. The preoperative assessment included a Doppler and a computed tomographic (CT) scan dating less than 3 months. A neurological examination was performed during the anesthesia consultation and in the 15 days before surgery. An MRI angiography was performed the day before and 3 days after surgery and was analyzed by an independent neuroradiologist. Preoperative analysis focused on the presence of ischemic events at MRI. The type of plaque, the supra aortic trunk lesions, and the quality of the circle of Willis were analyzed using Doppler and CT scanning. Postoperatively, we searched for signs of postoperative ischemic events at MRI. RESULTS: Forty-one patients were included (85.4% of men), and the mean age was 72.4 ± 8.3 years. We noted 7 (17.1%) contralateral stenoses (>50%) and 2 (4.9%) contralateral thromboses, 6 (14.6%) vertebral stenoses, and 7 (17.1%) abnormalities of the circle of Willis. The morphological analysis described 6 unstable plaques including 4 ulcerated, 1 pseudodissection, and 1 intraplaque hemorrhage. Preoperatively, we noted the presence of 21 (51.2%) ischemic lesions including 9 (21.9%) multiple lacunar ischemic events and 12 (29.3%) silent arterial territory infarcts. Eversion was performed for all patients except for 6 (14.6%), for whom a bypass was necessary. No deaths or major complications were observed in the 30 postoperative days. Postoperatively, MRI showed 3 (7.3%) asymptomatic recent ischemic strokes, 1 ipsilateral middle cerebral artery (MCA) stroke, and 2 contralateral (cerebellar and MCA) strokes. CONCLUSIONS: Patients with asymptomatic significant carotid stenosis show many preoperative SBI indicating a significant embolic risk. It is difficult to conclude about intraoperative embolic risk, but we hope that more data could demonstrate the importance of MRI for the preoperative evaluation of carotid plaques and brain parenchyma, to identify high-risk embolic patients.

Preoperative CT-scan-based sizing and in-stent restenosis in peripheral endovascular revascularizations.

Objectives This study evaluates the effect of stent sizing with CT-scan on the incidence of restenosis in peripheral arterial disease. Methods This retrospective study included 59 patients with 66 arterial lesions who underwent a endovascular procedure for peripheral arterial disease between April 2013 and October 2013. All patients had de novo iliac or femoral lesions, were candidates for an endovascular procedure alone and underwent CTA preoperatively. The stent actually implanted, whose dimensions were chosen on the basis of the operator's experience on an intraoperative 2D angiography, was compared to the "ideal" stent chosen retrospectively on the basis of precise lesion sizing by the preoperative CTA. Planning was considered "discordant" if there was a difference in length of more than 20 mm and/or a difference in diameter of more than 1 mm between the ideal stent and the actual stent. Results For iliac lesions, discordance essentially concerned stent diameter (36.1%), whereas stent length was the main reason for discordance for femoral lesions (36.7%). The median length of follow-up was 18 months (range 6-24). For iliac lesions, freedom from restenosis at 24 months was higher for patients with concordant planning (90% vs. 62.5%, p = 0.045). Most restenoses occurred in the external iliac artery, where there was a tendency towards oversizing of the implanted stent. For femoral lesions, the restenosis-free rate at 24 months was higher for patients with concordant planning (77.8% vs. 50%, p = 0.057). A multivariate analysis was conducted on the prediction of restenosis. Among factors, only discordant planning was found to be a significant predictor of restenosis with an odds ratio of 0.115 (95% confidence interval, 0.02-0.674; p = 0.016). Conclusion The absence of sizing for peripheral lesions engenders a tendency to choose the wrong stent, in particular in terms of diameter in iliac arteries and length in femoral arteries.

Endovascular Treatment of Infrarenal Aneurysms: Comparison of the Results of Second- and Third-Generation Stent Grafts.

BACKGROUND: The stent grafts used for endovascular abdominal aortic repair (EVAR) profited from many technological changes since their appearance. The objective of this study was to compare the medium-term results of the second- and third-generation stent grafts. METHODS: Three hundred thirty-four patients treated by EVAR between 2005 and 2013 were included in this retrospective study. Demographic, anatomical, perioperative, and follow-up data were collected in a prospective way in an electronic database and compared between 2 groups. The preoperative angio-computed tomographies were all analyzed in depth on a suitable three-dimensional work station. Group 1 (n = 219) represented the patients treated by second-generation stent grafts (Medtronic Talent(®), Cook Medical Zenith Flex(®), Vascutek-Terumo Anaconda(®), Gore Excluder low-porosity(®)) and group 2 (n = 115) represented the patients treated with third-generation stent grafts (Medtronic Enduring I and II(®), Cook Medical Zenith LP(®), Gore Excluder C3(®)). RESULTS: The mean follow-up was 42.4 ± 26.8 months with a longer duration in group 1 (52.4 ± 27.2 vs. 23.2 ± 10.9 months, P < 0.0001). The patients of group 2 had significantly more risk factors and cardiovascular comorbidities (coronary disease, tobacco addiction, dyslipidemia, peripheral arterial disease, chronic renal insufficiency). Anatomical characteristics were similar in the 2 groups, in particular regarding the iliac arteries which were significantly more calcified and had a smaller diameter in group 2. The rate of perioperative complications was similar in the 2 groups, in particular for complications related to the iliac axes (3.7% vs. 2.6%, P = 0.96). During the follow-up, there was no significant difference between the 2 groups in the rates of survival, reinterventions, or endoleaks and the progression of the aneurysmal sac. CONCLUSIONS: This study shows that third-generation stent grafts allow results comparable with those of the second-generation stent grafts in spite of more complex iliac anatomies. These results make it possible to expand the indications of EVAR to patients presenting more cardiovascular comorbidities without increasing the risk of complications in the short and medium term.

Sealing zones have a greater influence than iliac anatomy on the occurrence of limb occlusion following endovascular aortic aneurysm repair.

Limb occlusion is a well-known complication following endovascular aortic aneurysm repair (EVAR), and it very often leads to reoperation. The aim of this study is to identify predictive factors for limb occlusion following EVAR. Two hundred and twenty-four patients undergoing EVAR between 2004 and 2012 were included in this retrospective study. Demographics, anatomic, and follow-up data were compared between two groups (with or without thrombosis). Preoperative anatomy was analyzed with a dedicated workstation, using the Society of Vascular Surgery reporting standards. Eleven (4.9%) patients presented with a limb occlusion during follow-up (46 ± 12 months). Univariate analyses were first performed to investigate the influence of preoperative variables on limb occlusion. Then, variables with a p value <0.1 were included in the multivariate analysis and showed that in the occlusion group there was a greater rate of chronic renal failure (18.2% vs. 3.8%, p = 0.012), a more frequent occurrence of distal landing zones in the external iliac artery (15.4% vs. 2.1%, p = 0.006), and a smaller aortic neck diameter (21.0 ± 2.9 mm vs. 23.6 ± 3.3 mm, p = 0.014). Although iliac anatomy does not appear to have a significant influence on limb occlusion rate in the multivariate analysis, proximal and distal sealing zones appear to be involved in this complication.

Interest of fusion imaging and modern navigation tools with hybrid rooms in endovascular aortic procedures.

Because of the emergence of hybrid operating rooms, cone-beam CT scans (CBCT) allow new intraoperative imaging to be produced. Image fusion (3D preoperative CT scan overlaid onto 2D live fluoroscopy image) is the most popular application and makes it possible to navigate throughout the aorta and its branches without having to make use of an additional injection, and allows a reduction to be achieved in the quantity of contrast medium and irradiation required during complex procedures. Planning-oriented software available in hybrid rooms makes it possible to adjust to the patient and the nature of the procedure, the information that is relevant during the operation. CBCT can also be used as a diagnostic tool at the end of a procedure for the detection of endoleaks and could replace routine CT scans made during the first month following the procedure, indirectly contributing again to a reduction of X-ray and contrast agent doses.