Adrien Kaladji

Sizing for Endovascular Aneurysm Repair: Clinical Evaluation of a New Automated Three-Dimensional Software

BACKGROUND To assess the reproducibility and accuracy of the sizing procedure before aortic endograft implantation using new sizing automated software as compared with standard radiological procedures. METHODS On the basis of original spiral-computed tomography images, the sizing of 32 patients with abdominal aortic aneurysm treated by endovascular aneurysm repair (EVAR) was retrospectively compared. The first sizing was performed by a radiologist using a standard workstation (General electrics) and software (Advanced vessel analysis). The second was performed twice by two surgeons using a personal computer with automatic three-dimensional sizing software (Endosize; Therenva, Rennes, France). All diameters and lengths required before EVAR were measured (17 items). Moreover, 13 qualitative criteria regarding EVAR feasibility, including neck length, were compared. Intra- and interobserver variability with Endosize, as well as the variability between the two measurement methods were analyzed using the intraclass correlation coefficient (ICC) and Bland and Altmans method. Qualitative variables were analyzed using Fischers exact test and kappa coefficient. RESULTS Intraobserver variability with Endosize proved to be efficient. None of the ICCs were lower than 0.9, and more than 90% of the absolute differences between two measurements were less than 2 mm. Interobserver variability with Endosize was assessed in a similar manner. Measurement variability of vessel diameters was less marked than that of vessel lengths. This trend was observed for all datasets. Comparison of the two measurement methods demonstrated a good correlation (minimum ICC = 0.697; maximum ICC = 0.974), although less so than that observed using Endosize. Mean time consumption using Endosize was 13.1 ± 4.53 minutes (range: 7.2-32.7). Analysis of the alarm sets demonstrated a high agreement between observers (kappa coefficient = 0.81). CONCLUSIONS Sizing using the Endosize software is as reliable as conventional radiological procedures. Sizing by surgeons using an automated, user-friendly, and mobile tool appears to be reproducible.

Prediction of deformations during endovascular aortic aneurysm repair using finite element simulation.

During endovascular aortic aneurysm repair (EVAR), the introduction of medical devices deforms the arteries. The aim of the present study was to assess the feasibility of finite element simulation to predict arterial deformations during EVAR. The aortoiliac structure was extracted from the preoperative CT angiography of fourteen patients underwent EVAR. The simulation consists in modeling the deformation induced by the stiff wire used during EVAR. The results of the simulation were projected onto the intraoperative images, using a 3D/2D registration. The mean distance between the real and simulated guidewire was 2.3±1.1mm. Our results demonstrate that finite element simulation is feasible and appear to be reproducible in modeling device/tissue interactions and quantifying anatomic deformations during EVAR.

Evolution of the upper and lower landing site after endovascular aortic aneurysm repair.

BACKGROUND The evolution and correlation between the aortic neck and distally located iliac necks after endovascular treatment of abdominal aortic aneurysms (AAAs) was studied. METHODS Of 179 patients who had undergone AAA repair between 2003 and 2007, 61 received the same radiologic follow-up and were included in this retrospective study. Data for 61 aortic necks and 115 iliac arteries were analyzed using the preoperative scan, 1-month visit, and final follow-up, with a minimum mean follow-up of 24 ± 15.2 months. Three measurements were taken of the aortic neck: subrenal (D1a), 15 mm below the lowest renal artery (D1b), and at the origin of the aneurysm (D1c). Three measurements were taken at the level of the iliac arteries: origin (Da), middle (Db), and the iliac bifurcation (Dc). These measurements were analyzed using analysis of variance and Spearman correlation coefficient. The results were evaluated for subsequent endoleaks, migrations, and reinterventions. All diameters were compared between patients with a regression of >10% in the greatest diameter of AAA at last follow-up (group A, n = 35) and those without (group B, n = 26). RESULTS All diameters (in mm) increased significantly over time at the level of the proximal neck (D1a = 3.7 ± 2.8, P = .018; D1b = 4.4 ± 2.5, P = .016; D1c = 4.3 ± 3.1, P = .036) and iliac arteries (Da = 2.1 ± 0.2, P = .0006; Db = 2.5 ± 0.5, P = .0006; Dc = 3 ± 0.7, P = .007). The increase in diameters at the proximal neck and iliac arteries evolved independently (insignificant correlation), with the exception of D1b and Dc (P = .006), which showed a weak correlation (r = 0.363). The group A patients presented increases in all diameters, although to a less significant extent (P < .05) than group B patients. During follow-up, a proximal endoleak and a distal endoleak occurred, both requiring reintervention. CONCLUSIONS Our results show a trend toward dilatation of the aortic neck and iliac arteries, with no correlation between the two levels, even in patients with a regression of the aneurysm sac during follow-up. Although this study found no correlation with the occurrence of endoleaks, our results suggest the need for a longer follow-up, especially on the landing sites.

Safety and Accuracy of Endovascular Aneurysm Repair Without Pre-operative and Intra-operative Contrast Agent

BACKGROUND Severe chronic kidney disease is a major limitation for endovascular aortic aneurysm repair (EVAR). The aim of this study is to assess the safety and accuracy of fusion imaging, when performing EVAR in the absence of pre- and intra-operative contrast agents. METHODS From October 2013 to February 2014, every patient requiring EVAR and presenting with severe chronic renal impairment underwent a specific pre-operative imaging assessment, based on a non-enhanced CT scan. Centrelines were manually extracted and key points were placed at the landing zones. In house software makes it possible to artificially enhance the contrast between vascular structures and the surrounding tissue, by increasing the values attributed to the vascular structure voxels (500 Hounsfield units). EVAR was performed in a hybrid room (Zeego, Siemens), and the artificially enhanced CT scan was used for the construction of fusion imaging. The 3D vascular volume, together with the centrelines and key points, was overlaid onto the 2D live fluoroscopic image. RESULTS Six patients (mean age 77.1 years) were treated by EVAR (5 abdominal aneurysms and 1 thoracic aneurysm), using fusion imaging without a contrast agent. The median pre-operative estimated glomerular filtration rate (eGFR) was 17.5 mL/min/1.73 m2. No contrast was used during the procedure. No intra-operative endoleak was observed on the duplex scan. No deterioration was observed in the eGFR at 1 week (eGFR = 21.7, p = .49), nor at 1 month follow up (eGFR = 21, p = .28). The stent graft positioning error was assessed in terms of the difference between the effective and planned landing zones, measured on pre- and post-operative CT scans. The mean error was 1.3 mm at the proximal landing zone, and 6.5 mm at the distal landing zone. CONCLUSION EVAR without the use of pre-operative and intra-operative contrast agents appears to be safe and accurate for patients with severe chronic kidney disease.

Finite element simulation of the insertion of guidewires during an EVAR procedure: example of a complex patient case, a first step toward patient-specific parameterized models

Deformations of the vascular structure due to the insertion of tools during endovascular treatment of aneurysms of the abdominal aorta, unless properly anticipated during the preoperative planning phase, may be the source of intraoperative or postoperative complications. We propose here an explicit finite element simulation method which enables one to predict such deformations. This method is based on a mechanical model of the vascular structure which takes into account the nonlinear behavior of the arterial wall, the prestressing effect induced by the blood pressure and the mechanical support of the surrounding organs and structures. An analysis of the model sensitivity to the parameters used to represent this environment is done. This allows determining the parameters that have the largest influence on the quality of the prediction and also provides realistic values for each of them as no experimental data are available in the literature. Moreover, for the first time, the results are compared with 3D intraoperative data. This is done for a patient-specific case with a complex anatomy in order to assess the feasibility of the method. Finally, the predictive capability of the simulation is evaluated on a group of nine patients. The error between the final simulated and intraoperatively measured tool positions was 2.1 mm after the calibration phase on one patient. It results in a 4.6 ± 2.5 mm in average error for the blind evaluation on nine patients.

Internal Iliac Artery Stenosis: Diagnosis and How to Manage it in 2015.

Lower extremity arterial disease (LEAD) is a highly prevalent disease affecting 202 million people worldwide. Internal iliac artery stenosis (IIAS) is one of the localization of LEAD. This diagnosis is often neglected when a patient has a proximal walking pain since most physicians evoke a pseudoclaudication. Surprisingly, IIAS management is reported neither in the Trans-Atlantic Inter-Society Consensus II nor in the report of the American College Foundation/American Heart Association guidelines. The aims of this review are to present the current knowledge about the disease, how should it be managed in 2015 and what are the future research trends.

Finite-Element-Based Matching of Pre- and Intraoperative Data for Image-Guided Endovascular Aneurysm Repair

Endovascular repair of abdominal aortic aneurysms is a well-established technique throughout the medical and surgical communities. Although increasingly indicated, this technique does have some limitations. Because intervention is commonly performed under fluoroscopic control, 2-D visualization of the aneurysm requires the injection of a contrast agent. The projective nature of this imaging modality inevitably leads to topographic errors, and does not give information on arterial wall quality at the time of deployment. A specially adapted intraoperative navigation interface could increase deployment accuracy and reveal such information, which preoperative 3-D imaging might otherwise provide. One difficulty is the precise matching of preoperative data (images and models) and intraoperative observations affected by anatomical deformations due to tool-tissue interactions. Our proposed solution involves a finite-element-based preoperative simulation of tool-tissue interactions, its adaptive tuning regarding patient specific data, and the matching with intraoperative data. The biomechanical model was first tuned on a group of ten patients and assessed on a second group of eight patients.

Centerline is Not as Accurate as Outer Curvature Length to Estimate Thoracic Endograft Length

BACKGROUND To assess the accuracy of the aortic outer curvature length for thoracic endograft planning. METHODS Seventy-four patients (58 men, 66.4 ± 14 years) who underwent thoracic endovascular aortic repair between 2009 and 2011 treated with a Cook Medical endograft were enrolled in this retrospective study. Immediate postoperative CT scans were analysed using EndoSize software. Three vessel lengths were computed between two fixed landmarks placed at each end of the endograft: the straightline (axial) length, the centerline length and the outer curvature length. A tortuosity index was defined as the ratio of the centerline length/straightline length. A Student t test and a Pearson correlation coefficient were used to examine the results. RESULTS We found a significant difference between the centerline length (135.4 ± 24 mm) and that of the endograft (160 ± 29 mm) (p < .0001). This difference correlates with the tortuosity index (r = .818, p < .0001), the endograft length (r = .587, p < .0001), and the diameter of the endograft (r = .53, p < .0001). However, the outer curvature length (161.3 ± 29 mm) and the endograft length (160 ± 29 mm) were similar (p = .792). CONCLUSION The outer curvature length more accurately reflects that of the deployed endograft and may prove more accurate than centerlines in planning thoracic endografts.

Preoperative predictive factors of aneurysmal regression using the reporting standards for endovascular aortic aneurysm repair.

BACKGROUND Aneurysmal regression is a reliable marker for long-lasting success after endovascular aneurysm repair (EVAR). The aim of this study was to identify the preoperative factors that can predictably lead to aneurysmal sac regression after EVAR, according to the reporting standards of the Society for Vascular Surgery and the International Society of Cardiovascular Surgery (SVS/ISCVS). METHODS From 199 patients treated by EVAR between 2000 and 2009, 164 completed computed tomography angiographies and duplex scan follow-up images were available. All computed tomography angiographies for enrolled patients in this retrospective study were analyzed with Endosize software (Therenva, Rennes, France) to provide spatially correct 3-dimensional data in accordance with SVS/ISCVS recommendations. Anatomic parameters were graded according to the relevant severity grades. A severity score was calculated at the aortic neck, the abdominal aortic aneurysm, and the iliac arteries. Clinical and demographic factors were studied. Patients with aneurysmal regression >5 mm were assigned to group A (mean age, 71.4 ± 8.9 years) and the others to group B (76.3 ± 8.3 years). RESULTS Aneurysmal regression occurred in 66 patients (40.2%; group A). Univariate analyses showed smaller severity scores at the aortic neck (P = .02) and the iliac arteries (P = .002) in group A and calcifications and thrombus were less significant at the aortic neck (P = .003 and P = .02) and at the iliac arteries (P = .001 and P = .02), and inferior mesenteric artery patency was less frequent (68.2% vs 82.7%, P = .04). Two multivariate analyses were done: one considered the scores and the other the variables included in the scores. In the first, the patients of group A were younger (P = .002) and aortic neck calcifications were less significant (P = .007). In the second, group A patients were younger (P < .001) and the aortic neck scores were smaller (P = .04). There was no difference between the two groups in the type of implanted endoprosthesis or in the follow-up (group A: 46.4 ± 24 months; group B: 47.2 ± 22 months; P = .35). CONCLUSIONS In this study, the young age of the patients and their aortic neck quality, in particular the absence of neck calcification, appear to have been the main factors affecting aneurysm shrinkage, such that they represent a target population for the improvement of EVAR results.

Mid-term results of elective repair of extensive thoracic aortic pathology by the Evita Open Plus hybrid endoprosthesis only †

OBJECTIVES To describe the early and mid-term clinical and instrumental results of the frozen elephant trunk (FET) procedure using the recent Evita Open Plus hybrid endoprosthesis for elective one-stage treatment of extensive thoracic aortic disease. METHODS We reviewed 16 patients undergoing FET for post-dissection aneurysm (50%), true aneurysm (31%) or other aetiologies (19%), through median sternotomy and hypothermic circulatory arrest. An average 14 ± 7.6-month follow-up with regular contrast-enhanced control computed tomography scans was available. Four patients received preliminary carotid-subclavian bypass to improve spinal cord protection. Distal extension through endovascular deployment of stent-grafts into the descending aorta was performed during the same procedure in 3 patients. Concomitant procedures on the ascending aorta/root were done in 25% of cases. RESULTS There were no cases of operative mortality. Cases of neither cerebral stroke nor postoperative paraplegia were observed. Two cases of transient paraparesis and 1 case of Brown-Séquard syndrome occurred. At follow-up, there were no cases of endoleak or endotension. One patient was reoperated for distal completion (thoracoabdominal aortic replacement). CONCLUSIONS The FET using the Evita Open Plus device is a reliable and versatile treatment for one-step management of extensive disease of the aortic arch and the descending aorta. This strategy should be reserved for patients having limited preoperative comorbidities and good functional status.