Utilizing numerical simulations to prevent stent graft kinking during thoracic endovascular aortic repair

Numerical simulations of thoracic endovascular aortic repair (TEVAR) may be implemented in the preoperative workflow if credible and reliable. We present the application of a TEVAR simulation methodology to an 82-year-old woman with a penetrating atherosclerotic ulcer in the left hemiarch, that underwent a left common carotid artery to left subclavian artery bypass and consequent TEVAR in zone 2. During the intervention, kinking of the distal thoracic stent graft occurred and the simulation was able to reproduce this event. This report highlights the potential and reliability of TEVAR simulations to predict perioperative adverse events and short-term postoperative technical results. (J Vasc Surg Cases Innov Tech 2023;9:101269.

Validation and Verification of High-Fidelity Simulations of Thoracic Stent-Graft Implantation

Thoracic Endovascular Aortic Repair (TEVAR) is the preferred treatment option for thoracic aortic pathologies and consists of inserting a self-expandable stent-graft into the pathological region to restore the lumen. Computational models play a significant role in procedural planning and must be reliable. For this reason, in this work, high-fidelity Finite Element (FE) simulations are developed to model thoracic stent-grafts. Experimental crimp/release tests are performed to calibrate stent-grafts material parameters. Stent pre-stress is included in the stent-graft model. A new methodology for replicating device insertion and deployment with explicit FE simulations is proposed. To validate this simulation, the stent-graft is experimentally released into a 3D rigid aortic phantom with physiological anatomy and inspected in a computed tomography (CT) scan at different time points during deployment with an ad-hoc set-up. A verification analysis of the adopted modeling features compared to the literature is performed. With the proposed methodology the error with respect to the CT is on average 0.92 +/- 0.64%, while it is higher when literature models are adopted (on average 4.77 +/- 1.83%). The presented FE tool is versatile and customizable for different commercial devices and applicable to patient-specific analyses

Sex-related Outcomes after Thoracic Endovascular Repair for intact isolated Descending Thoracic Aortic Aneurysm: A Retrospective Cohort Study

OBJECTIVE: To evaluate the association between sex and outcomes following TEVAR for intact isolated descending thoracic aortic aneurysms (iiDTAA). SUMMARY BACKGROUND DATA: Data regarding sex-related long-term outcomes after TEVAR for iiDTAA are limited and conflicting results regarding perioperative outcomes have been reported. METHODS: We included all TEVAR for iiDTAA between 2014-2019 in the Vascular Quality Initiative linked to Medicare claims, allowing reliable assessment of long-term outcome data. Primary outcomes included 5-year mortality, reinterventions, and ruptures of the thoracic aorta. Secondarily we assessed perioperative outcomes. RESULTS: We identified 685 patients, of which 54% were females. Females had higher aortic size index (females vs. males: 3.31 [IQR, 2.81-3.85] cm/m2 vs. 2.93 [IQR, 2.42-3.36] cm/m2; P.05). CONCLUSIONS: Our findings suggest that females who undergo TEVAR for iiDTAA have similar 5-year and perioperative outcomes as compared with males

Applicability assessment for in-silico patient-specific TEVAR procedures

: Thoracic Endovascular Aortic Repair (TEVAR) is a minimally invasive technique to treat thoracic aorta pathologies and consists of placing a self-expandable stent-graft into the pathological region to restore the vessel lumen and recreate a more physiological condition. Exhaustive computational models, namely the finite element analysis, can be implemented to reproduce the clinical procedure. In this context, numerical models, if used for clinical applications, must be reliable and the simulation credibility should be proved to predict clinical procedure outcomes or to build in-silico clinical trials. This work aims first at applying a previously validated TEVAR methodology to a patient-specific case. Then, defining the TEVAR procedure performed on a patient population as the context of use, the overall applicability of the TEVAR modeling is assessed to demonstrate the reliability of the model itself following a step-by-step method based on the ASME V&V40 protocol. Validation evidence sources are identified for the specific context of use and adopted to demonstrate the applicability of the numerical procedure, thereby answering a question of interest that evaluates the deployed stent-graft configuration in the vessel

Application of local gentamicin in the treatment of deep sternal wound infection: a randomized controlled trial

OBJECTIVES: In patients with deep sternal wound infection (DSWI), primary closure of the sternal bone over high negative pressure Redon drains has shown to be a safe and feasible treatment method. Addition of local gentamicin could accelerate healing and improve clinical outcomes. METHODS: We conducted a randomized controlled trial to evaluate the effectiveness of local gentamicin in the treatment of DSWI. In the treatment group, collagenous carriers containing gentamicin were left between the sternal halves during sternal refixation. In the control group, no local antibiotics were used. Primary outcome was hospital stay. Secondary outcomes were mortality, reoperation, wound sterilization time, time till removal of all drains and duration of intravenous antibiotic treatment. RESULTS: Forty-one patients were included in the trial of which 20 were allocated to the treatment group. Baseline characteristics were similar in both groups. Drains could be removed after a median of 8.5 days in the treatment group and 14.5 days in the control group (P-value: 0.343). Intravenous antibiotics were administered for a median of 23.5 days in the treatment group and 38.5 days in the control group (P-value: 0.343). The median hospital stay was 27 days in the treatment group and 28 days in the control group (P-value: 0.873). Mortality rate was 10% in the treatment group and 9.5% in the control group (P-value: 0,959). No side effects were observed. CONCLUSIONS: This randomized controlled trial showed that addition of local gentamicin in the treatment of DSWI did not result in shorter length of stay. Clinical trial registration number: 2014-001170-33

Thoracic Stent Graft Numerical Models To Virtually Simulate Thoracic Endovascular Aortic Repair: A Scoping Review

Objective: Pre-procedural planning of thoracic endovascular aortic repair (TEVAR) may implement computational adjuncts to predict technical and clinical outcomes. The aim of this scoping review was to explore the currently available TEVAR procedure and stent graft modelling options. Data sources: PubMed (MEDLINE), Scopus, and Web of Science were systematically searched (English language, up to 9 December 2022) for studies presenting a virtual thoracic stent graft model or TEVAR simulation. Review methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) was followed. Qualitative and quantitative data were extracted, compared, grouped, and described. Quality assessment was performed using a 16 item rating rubric. Results: Fourteen studies were included. Among the currently available in silico simulations of TEVAR, severe heterogeneity exists in study characteristics, methodological details, and evaluated outcomes. Ten studies (71.4%) were published during the last five years. Eleven studies (78.6%) included heterogeneous clinical data to reconstruct patient specific aortic anatomy and disease (e.g., type B aortic dissection, thoracic aortic aneurysm) from computed tomography angiography imaging. Three studies (21.4%) constructed idealised aortic models with literature input. The applied numerical methods consisted of computational fluid dynamics analysing aortic haemodynamics in three studies (21.4%) and finite element analysis analysing structural mechanics in the others (78.6%), including or excluding aortic wall mechanical properties. The thoracic stent graft was modelled as two separate components (e.g., graft, nitinol) in 10 studies (71.4%), as a one component homogenised approximation (n = 3, 21.4%), or including nitinol rings only (n = 1, 7.1%). Other simulation components included the catheter for virtual TEVAR deployment and numerous outcomes (e.g., Von Mises stresses, stent graft apposition, drag forces) were evaluated. Conclusion: This scoping review identified 14 severely heterogeneous TEVAR simulation models, mostly of intermediate quality. The review concludes there is a need for continuous collaborative efforts to improve the homogeneity, credibility, and reliability of TEVAR simulations

Cardiac and Aortic Modifications After Endovascular Repair for Blunt Thoracic Aortic Injury: A Systematic Review

Objective: Blunt thoracic aortic injury (BTAI) is a devastating condition that commonly occurs in healthy and young patients. Endovascular treatment is the first choice; however, it has also been demonstrated to alter cardiovascular haemodynamics. The aim of this systematic review was to describe the cardiovascular modifications after thoracic endovascular aortic repair (TEVAR) for BTAI. Data Sources: PubMed (MEDLINE), Scopus, and Web of Science were systematically searched for eligible studies reporting on modifications in aortic stiffness, blood pressure, cardiac mass, and aortic size. Review Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was followed. The Newcastle–Ottawa Scale was used to assess the methodological quality of included studies. Results: A total of 12 studies reporting on 265 patients were included. Severe heterogeneity existed among the included studies with regard to demographics, BTAI grade, endograft specifications, reported outcomes, and the method of evaluation. Regarding aortic stiffness, two studies found a significant increase in pulse wave velocity (PWV) in patients after TEVAR compared with a control group, while one did not find a significant increase in PWV and augmentation index after > 3 years of follow up. Five studies reported an increase in the incidence of post-TEVAR hypertension up to 55% (range 34.8% – 55.0%) vs. baseline. One study found a statistically significant increase in left ventricular mass and left ventricular mass index during follow up. Nine studies report data regarding aortic dilatation or remodelling after TEVAR. One found a 2.4 fold faster growth rate in ascending aortic diameter vs. controls, while other studies described significant changes in aortic size at different locations along the aorta and endograft after TEVAR. Conclusion: This systematic review highlights adverse cardiac and aortic modifications after TEVAR for BTAI. The results stress the need for lifelong surveillance in these patients and the necessity of developing a more compliant endograft to prevent cardiovascular complications in the long term

Comparison of Two Generations of Thoracic Aortic Stent Grafts and Their Impact on Aortic Stiffness in an Ex Vivo Porcine ModelWhat this paper adds

Objective: Little is known about the cardiovascular changes after TEVAR and regarding the impact on aortic stiffness for different stent graft generations specifically, following changes in device design. The present study evaluated the stent graft induced aortic stiffening of two generations of the Valiant thoracic aortic stent graft. Methods: This was an ex vivo porcine investigation using an experimental mock circulatory loop. Thoracic aortas of young healthy pigs were harvested and connected to the mock circulatory loop. At a 60 bpm heart rate and stable mean arterial pressure, baseline aortic characteristics were obtained. Pulse wave velocity (PWV) was calculated before and after stent graft deployment. Paired and independent sample t tests or their non-parametric alternatives were performed to test for differences where appropriate. Results: Twenty porcine thoracic aortas were divided into two equal subgroups, in which a Valiant Captivia or a Valiant Navion stent graft was deployed. Both stent grafts were similar in diameter and length. Baseline aortic characteristics did not differ between the subgroups. Mean arterial pressure values did not change after either stent graft, while pulse pressures increased statistically significantly after Captivia (mean 44 ± 10 mmHg to 51 ± 13 mmHg, p = .002) but not after Navion. Mean baseline PWV increased after both Captivia (4.4 ± 0.6 m/s to 4.8 ± 0.7 m/s, p = .007) and Navion (4.6 ± 0.7 m/s to 4.9 ± 0.7 m/s, p = .002). There was no statistically significant difference in the mean percentage increase in PWV for either subgroup (8 ± 4% vs. 6 ± 4%, p = .25). Conclusion: These experimental findings showed no statistically significant difference in the percentage increase of aortic PWV after either stent graft generation and confirm that TEVAR increases aortic PWV. As a surrogate for aortic stiffness, this calls for further improvements in future thoracic aortic stent graft designs regarding device compliance

Utilizing numerical simulations to prevent stent graft kinking during thoracic endovascular aortic repair

Numerical simulations of thoracic endovascular aortic repair (TEVAR) may be implemented in the preoperative workflow if credible and reliable. We present the application of a TEVAR simulation methodology to an 82-year-old woman with a penetrating atherosclerotic ulcer in the left hemiarch, that underwent a left common carotid artery to left subclavian artery bypass and consequent TEVAR in zone 2. During the intervention, kinking of the distal thoracic stent graft occurred and the simulation was able to reproduce this event. This report highlights the potential and reliability of TEVAR simulations to predict perioperative adverse events and short-term postoperative technical results

Type III aortic arch angulation increases aortic stiffness: Analysis from an ex vivo porcine modelCentral MessagePerspective

Objective: The relationship among increased aortic arch angulation, aortic flow dynamics, and vessel wall stiffness remains unclear. This experimental ex vivo study investigated how increased aortic arch angulation affects aortic stiffness and stent-graft induced aortic stiffening, assessed by pulse wave velocity (PWV). Methods: Porcine thoracic aortas were connected to a circulatory mock loop in a Type I and Type III aortic arch configuration. Baseline characteristics and blood pressures were measured. Proximal and distal flow curves were acquired to calculate PWV in both arch configurations. After that, a thoracic stent-graft (VAMF2626C100TU) was deployed in aortas with adequate proximal landing zone diameters to reach 10% t0 20% oversizing. Acquisitions were repeated for both arch configurations after stent-graft deployment. Results: Twenty-four aortas were harvested, surgically prepared, and mounted. Cardiac output was kept constant for both arch configurations (Type I: 4.74 ± 0.40 and Type III: 4.72 ± 0.38 L/minute; P = .703). Compared with a Type I arch, aortic PWV increased significantly in the Type III arch (3.53 ± 0.40 vs 3.83 ± 0.40 m/second; P < .001), as well as blood pressures. A stent-graft was deployed in 15 aortas. After deployment, Type I arch PWV increased (3.55 ± 0.39 vs 3.81 ± 0.44 m/second; P < .001) and Type III arch PWV increased although not significantly (3.86 ± 0.42 vs 4.03 ± 0.46 m/second; P = .094). Type III arch PWV resulted the highest and significantly higher compared with the Type I arch after stent-graft deployment (3.81 ± 0.44 vs 4.03 ± 0.46 m/second; P = .023). Conclusions: Increased aortic arch angulation—as in a Type III arch—is associated with higher aortic PWV and blood pressures and this may negatively influence cardiovascular health