Endovascular aneurysm repair (EVAR) can involve some unfavorable complications such as endoleaks or stent-graft (SG) migration. Such complications, resulting from the complex mechanical interaction of vascular tissue, SG and blood flow or incompatibility of SG design and vessel geometry, are difficult to predict. Computational vascular mechanics models can be a predictive tool for the selection, sizing and placement process of SGs depending on the patient-specific vessel geometry and hence reduce the risk of potential complications after EVAR. In this contribution, we present a new in silico EVAR methodology to predict the final state of the deployed SG after intervention and evaluate the mechanical state of vessel and SG, such as contact forces and wall stresses. A novel method to account for residual strains and stresses in SGs, resulting from the precompression of stents during the assembly process of SGs, is presented. We suggest a parameter continuation approach to model various different sizes of SGs within one in silico EVAR simulation which can be a valuable tool when investigating the issue of SG oversizing. The applicability and robustness of the proposed methods are demonstrated on the example of a synthetic abdominal aortic aneurysm geometry.

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Non-negligible postinterventional complication rates after endovascular aneurysm repair (EVAR) leave room for further improvements. Since the potential success of EVAR depends on various patientspecific 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 preinterven

The variety of stent‐graft (SG) design variables (eg, SG type and degree of SG oversizing) and the complexity of decision making whether a patient is suitable for endovascular aneurysm repair (EVAR) raise the need for the development of predictive tools to assist clinicians in the preinterventional planning phase. Recently, some in silico EVAR methods have been developed to predict the deployed SG configuration. However, only few studies investigated how to assess the in silico EVAR outcome with respect to EVAR complication likelihoods (eg, endoleaks and SG migration). Based on a large literature study, in this contribution, 20 mechanical and geometrical parameters (eg, SG drag force and SG fixation force) are defined to evaluate the quality of the in silico EVAR outcome. For a cohort of n = 146 realizations of parameterized vessel and SG geometries, the in silico EVAR results are studied with respect to these mechanical and geometrical parameters. All degrees of SG oversizing in the range between 5% and 40% are investigated continuously by a computationally efficient parameter continuation approach. The in silico investigations have shown that the mechanical and geometrical parameters are able to indicate candidates at high risk of postinterventional complications. Hence, this study provides the basis for the development of a simulation‐based metric to assess the potential success of EVAR based on engineering parameters.

This study confirmed the over expression of CXCR4 in human AAA tissue. CXCR4 was detected both at the mRNA and the protein level and by immunohistochemistry, especially in inflammatory cells. In contrast, CXCL12 expression was observed only at the mRNA level, with the exception of plasma cells. The exact role of CXCR4/CXCL12 in AAA has to be further elucidated.

Work-life balance is a commonly used term that appears in different contexts and has a different meaning for many colleagues. Unfortunately, however, it is often used as a negative, simplified term to describe the assumed attitude of young surgeons towards work and a medical career, even though this is not universally applicable. As the representatives for Young Surgeons of the German Society of Surgery the aim of this article is to present our thoughts on the issue and associated problems and provide a differentiated outline for discussion.

ZusammenfassungHintergrund: Die endovaskuläre Behandlung (EVAR) von abdominalen Aortenaneurysmen (AAA) erfordert einen komplexen und bisher stark erfahrungsbasierten präoperativen Planungsprozess z. B. bzgl. Stentgrafttypen Auswahl und Oversizing, welcher an die individuellen patientenspezifischen Gegebenheiten angepasst sein muss. Fragestellung: Ob die Verwendung eines virtuellen digitalen Zwillings potentiell hilfreich sein kann diesen erfahrungsbasierten Planungsprozess zu objektivieren und zu optimieren, um damit das methodenassoziierte Komplikationsrisiko zu senken, soll in der vorliegenden Arbeit untersucht werden. Methoden: Basierend auf präoperativen patientenspezifischen Daten werden wirklichkeitsgetreue AAA sowie wirklichkeitsgetreue Stentgraft Simulationsmodelle gängiger kommerzieller Stentgrafts erzeugt. Anschließend wird eine virtuelle endovaskuläre AAA Reparatur zur Vorhersage der postoperativen Konfiguration von Stentgraft und AAA verwendet. Unterschiedliche Anwendungsbeispiele dieser Prozesskette sollen den potentiellen Nutzen eines digitalen Zwillings in der endovaskulären Therapie aufzeigen. Ergebnisse: Die potentielle Anwendbarkeit und der Nutzen eines digitalen Zwillings zur Optimierung der präoperativen Stentgraft Auswahl und Größenbestimmung sowie zur prädiktiven Einschätzung der Komplikationswahrscheinlichkeit basierend auf mechanischen und geometrischen Kenngrößen konnten exemplarisch demonstriert und validifiziert werden. Schlussfolgerungen: Die gute Vorhersagegüte macht den digitalen Zwilling zu einem vielversprechenden Planungswerkzeug in der präoperativen Planungsphase der endovaskulären AAA Versorgung mit denkbar vielseitigen Anwendungsmöglichkeiten. Schlüsselwörter abdominales Aortenaneurysma, endovaskuläre Aneurysmareparatur, Stentgraft, personalisierte Medizin, digitaler ZwillingThe digital twin in the endovascular repair Abstract Background: Endovascular aortic repair (EVAR) of abdominal aortic aneurysms (AAA) requires a very complex preoperative planning process, e.g. with respect to stent--graft selection and stent--graft oversizing, which must be individually adapted to the patient-specific case and which is strongly based on the interventionalist's experience. Objectives: In this study, it is investigated whether the use of a digital twin could increase objectivity and optimize the experience based preoperative planning process and hence reduce the method--associated complication rate. Methods: Based on preoperative patient--specific data, realistic AAA and realistic stent-graft simulation models of common commercial stent--grafts are generated. Subsequently, virtual endovascular AAA repair is used to predict the postoperative configuration of stent--graft and AAA. Different application examples of this process chain are intended to demonstrate the potential benefits of the use of a digital twin in EVAR. Results: The potential applicability and the benefit of a digital twin for the optimization of the preoperative stent--graft selection and sizing as well as for the predictive...

Hemiarch hybrid repair in high-risk patients is associated with an acceptable perioperative mortality risk and long-term survival. Zone 2 represents a feasible and effective treatment option for hybrid arch repair. Zone 1 is related with relevant risk for type Ia endoleak and higher mortality during follow-up. Lifelong surveillance after hybrid repair is essential.