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Vascular remodeling after endovascular treatment: quantitative analysis of medical images with a focus on aorta
No full textIn the last years, the convergence of advanced imaging techniques and endovascular procedures
has revolutionized the practice of vascular surgery. However, regardless the anatomical
district, several complications still occur after endovascular treatment and the impact of endovascular
repair on vessel morphology remains unclear. Starting from this background, the
aim of this thesis is to ll the gaps in the eld of vessel remodeling after endovascular procedure.
Main focus of the work will be the repair of the aorta and, in particular thoracic and
thoracoabdominal treatments. Furthermore an investigation of the impact of endovascular
repair on femoro-popliteal arterial segment will be reported in the present work. Analyses of
medical images will been conducted to extract anatomical geometric features and to compare
the changes in morphology before treatment and during follow-up.
After illustrating in detail the aims and the outline of the dissertation in Chapter 1, Chapter
2 will concern the anatomy and the physiology of the aorta along with the main aortic
pathologies and the related surgical treatments. Subsequently, an overview of the medical
image techniques for segmentation and vessel geometric quantication will be provided.
Chapter 3 will introduce the concept of remodeling of the aorta after endovascular procedure.
In particular, two types of aortic remodeling will be considered. On one side remodeling can
be seen as the shrinkage of the aneurysmal sac or false lumen thrombosis. On the other side,
aortic remodeling could be seen as the changes in the aortic morphology following endograft
placement which could lead to complications.
Chapter 4 will illustrate a study regarding the analysis of medical images to measure the geometrical
changes in the pathological aorta during follow-up in patients with thoracoabdominal
aortic aneurysms treated with endovascular procedure using a novel uncovered device, the Cardiatis
Multilayer Flow Modulator.
Chapter 5 will focus on the geometrical remodeling of the aortic arch and descending aorta in
patients who underwent hybrid arch treatment to treat thoracic aneurysms. The goal of the
work is to develop a pipeline for the processing of pre-operative and post-operative Computed
Tomography images in order to detect the changes in the aortic arch physiological curvature
due to endograft insertion.
Chapter 6 will focuse on the use of 3D printing technology as valuable tool to support patient's
follow-up. In particular, we report a case of a patient originally treated with endovascular
procedure for type B aortic dissection and which experimented several complications during
follow-up. 3D printing technology is used to show the remodeling of the aortic vasculature
during time.
Chapter 7 will concern patient-specic nite element simulations of aortic endovascular procedure.
In particular, starting from a clinical case where complication developed during followup,
the predictive value of computational simulations will be shown.
Chapter 8 will illustrate a study concerning the evaluation of morphological changes of the
femoro-popliteal arterial segment due to limb exion in patients undergoing endovascular
treatment of popliteal artery aneurysms
Finite element analysis of TAVI: Impact of native aortic root computational modeling strategies on simulation outcomes
No full textIn the last few years, several studies, each with different aim and modeling detail, have been proposed to investigate transcatheter aortic valve implantation (TAVI) with finite elements. The present work focuses on the patient-specific finite element modeling of the aortic valve complex. In particular, we aim at investigating how different modeling strategies in terms of material models/properties and discretization procedures can impact analysis results. Four different choices both for the mesh size (from 20k elements to 200k elements) and for the material model (from rigid to hyperelastic anisotropic) are considered. Different approaches for modeling calcifications are also taken into account. Post-operative CT data of the real implant are used as reference solution with the aim of outlining a trade-off between computational model complexity and reliability of the results
Midterm Follow-up Geometrical Analysis of Thoracoabdominal Aortic Aneurysms Treated with Multilayer Flow Modulator
No full textBackground: Aim of our study is the analysis of clinical results and aneurysmal sac evolution after multilayer flow modulator (MFM) placement, in patients with thoracoabdominal aortic aneurysms (TAAs). Methods: All patients with asymptomatic TAA treated at our institution between 2012 and 2014 with MFM were retrospectively analyzed. Thirty-day evaluated outcomes were mortality and complications. Follow-up evaluated outcomes were mortality, aneurysm collateral branches patency, and reintervention. A geometrical analysis of 2-year follow-up computed tomography scans was carried out to evaluate the total aneurysm volume, the percentage of aneurysm growth, and the evolution of maximum aneurysm diameter. Results: Seven patients (mean age: 71.8 years, range: 63–85 years) were considered in the study. Mean preoperative aneurysm diameter was 6.8 cm (range 6–8.3 cm). No 30-day mortality or complications were observed. Mean follow-up was 29.4 months. During follow-up, 3 deaths (42.8%) were observed, not related to MFM complications. Reintervention rate was 42.8%, occurred in all cases after 2-year follow-up; in 2 cases, the reintervention was necessary due to an excessive increase of the aneurysmal sac. During the follow-up, a mean growth rate of 6 mm/year (4 patients) for the diameter of the aneurysm external wall and a total aneurysm volume increase from 2.45 × 105 mm3 to 3.50 × 105 mm3 (4 patients) was evaluated. Conclusions: Our results have shown no mortality related to aneurysm rupture during the follow-up and high rate of reinterventions after MFM placement. Further geometrical analyses, based on the proposed approach, regarding a larger group of patients with long-term follow-up are required to draw indications about the MFM use
Performance of high conformability vs. high radial force devices in the virtual treatment of TAVI patients with Bicuspid Aortic Valve
No full textObjective: Transcatheter Aortic Valve Implantation (TAVI) is a consolidated procedure showing a low operative risk and excellent long-term outcomes in patients with aortic stenosis. Patients presenting a bicuspid aortic valve (BAV) often require valve replacement due to the highly calcific nature of the aortic leaflets. However, BAV patients have usually been contraindicated for TAVI due to their complex valve anatomy. The aim of this work was to compare the performance of devices featuring high conformability (HC) against those with high radial force (HRF). Methods: Four BAV patients undergoing TAVI were retrospectively selected. The aortic root including the native leaflets and calcifications were reconstructed from pre-operative Computed Tomography scans. In each patient, both HC and HRF devices were virtually implanted using Finite Element Analysis simulations. After implantation, paravalvular orifice area, von Mises stress distribution, root contact area, and device eccentricity were calculated. Results: Simulations showed good agreement with intraoperative imaging. In 3 out of 4 patients, the HRF device resulted in a lower paravalvular area than the HC. Stress distribution was also more homogeneously distributed in the HRF group as compared with the HC group. Despite their lower adaptability, HRF devices showed consistently higher stent-root contact area. Conclusion: HRF devices showed improved results with respect to HC valves after being deployed in BAV anatomies. We hypothesize that the ability to reshape the annulus is the major determinant of success in this subgroup of patients featuring highly calcified leaflets
Assessment of geometrical remodelling of the aortic arch after hybrid treatment
No full textThe aim of this study was to measure the morphological remodelling of the ascending aorta, aortic arch and thoracic aorta after aortic arch hybrid treatment including debranching and stent graft implantation. Preoperative, 1-month and 1-year follow-up of computed tomography angiography scans of 22 patients were analysed to compute the lumen centreline from the aortic root to the coeliac trunk, and the following measurements were derived: the total centreline length, distance from the aortic root to the left subclavian artery, distance from the left subclavian artery to the distal landing zone. For both pre- and postoperative centrelines, the pointwise curvature was measured at the proximal and the distal landing zones. The meancurvature values of the whole aortic segment and the endografting region of the ascending and the descending aorta were measured. Surface outerline was computed as well, and curvature values at the endograft landing points were extracted. At the 1-month follow-up, centreline length were already significantly increased (382.66 48.69 to 388.1 50.75 mm; P = 0.01). Centreline pointwise curvature increased in the proximal (+29%, P = 0.011) and the distal zones (+63%, P = 0.004). Similarly, pointwise curvature of the outerline significantly increased in the proximal (+77%, P = 0.01) and the distal landing zones (+100%, P = 0.04). The centreline mean curvature increased in the ascending aorta (+7%, P = 0.02) and decreased in the endografting region (-3.3%, P = 0.004). No evidence of a relationship of such a remodelling with the type of endograft and the type of pathology was observed. This remodelling trend was confirmed by the analysis of 1-year computed tomography angiographies. Hybrid arch repair was associated with a significant elongation of the vessel and a significant increase in the curvature on the ascending aorta and the descending aorta and on the endograft proximal and the distal landing zones.. © The Author(s) 2018. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved
Twelve-year Follow-up Post–Thoracic Endovascular Repair in Type B Aortic Dissection Shown by Three-dimensional Printing
No full textBackground: Thoracic endovascular repair (TEVAR) is currently considered the therapy of choice for complicated type B acute aortic dissection (TBAAD). Although several papers have reported good outcomes at short- and medium-term follow-up, some questions still remain regarding the long-term durability and re-intervention rate during follow-up. Methods: We describe a case of a patient originally treated with TEVAR for TBAAD complicated by impending aortic rupture. Results: Endovascular repair successfully excluded the flow through the primary entry tear but during the 12-year follow-up period the patient experienced several complications and re-interventions. Various full-size three-dimensional (3D) models of the patient-specific vasculature were printed to better explain the different interventional interventions over the 12 years of follow-up and as a hands-on tool for medical education. Conclusions: The present case report, involving long-term follow-up, provides an example of the effectiveness and the safety of TEVAR for the treatment of complicated TBAAD shown at short and medium-term follow-up. However, the long-term complications that were observed in this patient during follow-up support the importance of lifelong CTA surveillance. Furthermore, this study confirms the capability of 3D printing technology as a powerful tool to support communication with patients and residents’ education through the physical analysis of the real cases
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Early Experience of Inner Branch Retrograde Cannulation With E-nside Branch Stent Graft for Thoracoabdominal Aortic Aneurysms
No full textPurpose: The aim of our study is to investigate the feasibility of retrograde cannulation using devices with inner branches (IB) for the endovascular treatment of thoracoabdominal aortic aneurysms (TAAAs). Materials and Methods: A retrospective analysis using IB configuration with retrograde cannulation was carried out on TAAAs patients undergoing endovascular treatment. Results: Seven patients underwent IB endovascular treatment with retrograde cannulation between September 2020 and November 2021. The mean age was 80.4 years and 4 patients were male. A total of 26 of 28 target vessels were cannulated by retrograde access with a technical success of 93% (2 of 26 target vessels). Two intra-procedural complications were observed (1 renal artery dissection and 1 collateral renal artery rupture). In total, 26 of 28 treated vessels were retrograde cannulated with a technical success of 93%. A total of 39 stent bridges were used (all Viabahn VBX devices). The mean duration of the procedure was 321 +/- 102 minutes, and the mean scan time was 134 +/- 62 minutes. Mortality at 30 days was observed in 1 case. During the follow-up, 1 stent bridge occlusion was observed without the need for reintervention. Conclusion: Retrograde cannulation can also be successfully performed in the case of inner branches. Clinical Impact In inner branched cases, retrograde cannulation should be taken into consideration in particular cases or it could become the option of choice. Dedicated endovascular material available such as steerable catheters and latest generation covered stents is fundamental for the success of the treatment
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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