Virtual and analytical self-expandable braided stent treatment models.

The Flow Diverter is a self-expandable braided stent that has helped improve the effectiveness of cerebral aneurysm treatment during the last decade. The Flow Diverter's efficiency heavily relies on proper decision-making during the pre-operative phase, which is currently based on static measurements that fail to account for vessel or tissue deformation. In the context of providing realistic measurements, a biomechanical computational method is designed to aid physicians in predicting patient-specific treatment outcomes. The method integrates virtual and analytical treatment models, validated against experimental mechanical tests, and two patient treatment outcomes. In the case of both patients, deployed stent length was one of the validated result parameters, which displayed an error inferior to 1.5% for the virtual and analytical models. These results indicated both models' accuracy. However, the analytical model provided more accurate results with a 0.3% error while requiring a lower computational cost for length prediction. This computational method can offer designing and testing platforms for predicting possible intervention-related complications, patient-specific medical device designs, and pre-operative planning to automate interventional procedures.

Vacuum curette lumbar discectomy mechanics for use in spine surgical training simulators.

Simulation in surgical training is a growing field and this study aims to understand the force and torque experienced during lumbar spine surgery to design simulator haptic feedback. It was hypothesized that force and torque would differ among lumbar spine levels and the amount of tissue removed by ≥ 7%, which would be detectable to a user. Force and torque profiles were measured during vacuum curette insertion and torsion, respectively, in multiple spinal levels on two cadavers. Multiple tests per level were performed. Linear and torsional resistances of 2.1 ± 1.6 N/mm and 5.6 ± 4.3 N mm/°, respectively, were quantified. Statistically significant differences were found in linear and torsional resistances between all passes through disc tissue (both p = 0.001). Tool depth (p < 0.001) and lumbar level (p < 0.001) impacted torsional resistance while tool speed affected linear resistance (p = 0.022). Average differences in these statistically significant comparisons were ≥ 7% and therefore detectable to a surgeon. The aforementioned factors should be considered when developing haptic force and torque feedback, as they will add to the simulated lumbar discectomy realism. These data can additionally be used inform next generation tool design. Advances in training and tools may help improve future surgeon training.

Impact of calcification modeling to improve image fusion accuracy for endovascular aortic aneurysm repair.

Since the 1990s, endovascular aortic aneurysm repair (EVAR) has become a common alternative to open surgery for the treatment of abdominal aortic aneurysms (AAAs). To aid the deployment of stent-grafts, fluoroscopic image guidance can be enhanced using preoperative simulation and intraoperative image fusion techniques. However, the impact of calcification (Ca) presence on the guidance accuracy of such techniques is yet to be considered. In the present work, we introduce a guidance tool that accounts for patient-specific Ca presence. Numerical simulations of EVAR were developed for 12 elective AAA patients, both with (With-Ca) and without (No-Ca) Ca consideration. To assess the accuracy of the simulations, the image results were overlaid on corresponding intraoperative images and the overlay error was measured at selected anatomical landmarks. With this approach we gained insight into the impact of Ca presence on image fusion accuracy. Inclusion of Ca improved mean image fusion accuracy by 8.68 ± 4.59%. In addition, a positive correlation between the relative Ca presence and the image fusion accuracy was found (R = .753, p < .005). Our results suggest that considering Ca presence in patient-specific EVAR simulations increases the reliability of EVAR image guidance techniques that utilize numerical simulation, especially for patients with severe aortic Ca presence.

3D printed ascending aortic simulators with physiological fidelity for surgical simulation.

Introduction: Three-dimensional (3D) printed multimaterial ascending aortic simulators were created to evaluate the ability of polyjet technology to replicate the distensibility of human aortic tissue when perfused at physiological pressures. Methods: Simulators were developed by computer-aided design and 3D printed with a Connex3 Objet500 printer. Two geometries were compared (straight tube and idealised aortic aneurysm) with two different material variants (TangoPlus pure elastic and TangoPlus with VeroWhite embedded fibres). Under physiological pressure, ß Stiffness Index was calculated comparing stiffness between our simulators and human ascending aortas. The simulators' material properties were verified by tensile testing to measure the stiffness and energy loss of the printed geometries and composition. Results: The simulators' geometry had no effect on measured ß Stiffness Index (p>0.05); however, ß Stiffness Index increased significantly in both geometries with the addition of embedded fibres (p<0.001). The simulators with rigid embedded fibres were significantly stiffer than average patient values (41.8±17.0, p<0.001); however, exhibited values that overlapped with the top quartile range of human tissue data suggesting embedding fibres can help replicate pathological human aortic tissue. Biaxial tensile testing showed that fiber-embedded models had significantly higher stiffness and energy loss as compared with models with only elastic material for both tubular and aneurysmal geometries (stiffness: p<0.001; energy loss: p<0.001). The geometry of the aortic simulator did not statistically affect the tensile tested stiffness or energy loss (stiffness: p=0.221; energy loss: p=0.713). Conclusion: We developed dynamic ultrasound-compatible aortic simulators capable of reproducing distensibility of real aortas under physiological pressures. Using 3D printed composites, we are able to tune the stiffness of our simulators which allows us to better represent the stiffness variation seen in human tissue. These models are a step towards achieving better simulator fidelity and have the potential to be effective tools for surgical training.

Development of a micro-scale method to assess the effect of corrosion on the mechanical properties of a biodegradable Fe-316L stent material.

The application of biodegradable materials to stent design has the potential to transform coronary artery disease treatment. It is critical that biodegradable stents have sustained strength during degradation and vessel healing to prevent re-occlusion. Proper assessment of the impact of corrosion on the mechanical behaviour of potential biomaterials is important. Investigations within literature frequently implement simplified testing conditions to understand this behaviour and fail to consider size effects associated with strut thickness, or the increase in corrosion due to blood flow, both of which can impact material properties. A protocol was developed that utilizes micro-scale specimens, in conjunction with dynamic degradation, to assess the effect of corrosion on the mechanical properties of a novel Fe-316L material. Dynamic degradation led to increased specimen corrosion, resulting in a greater reduction in strength after 48 h of degradation in comparison to samples statically corroded. It was found that thicker micro-tensile samples (h > 200 µm) had a greater loss of strength in comparison to its thinner counterpart (h < 200 µm), due to increased corrosion of the thicker samples (203 MPa versus 260 MPa after 48 h, p = 0.0017). This investigation emphasizes the necessity of implementing physiologically relevant testing conditions, including dynamic corrosion and stent strut thickness, when evaluating potential biomaterials for biodegradable stent application.

A novel fiber-optic based 0.014″ pressure wire: Designs of the OptoWire™, development phases, and the O2 first-in-man results.

OBJECTIVES: To review the technical limitations of available pressure-wires, present the design evolution of a nitinol fiber-optic pressure wire and to summarize the First-in-Man (FIM) O2 pilot study results. BACKGROUND: Despite increasing use of physiology assessment of coronary lesions, several technical limitations persist. We present technical details, design evolution and early clinical results with a novel 0.014" nitinol fiber-optic based pressure-wire. METHODS AND RESULTS: The 0.014' OptoWire™ (Opsens Medical, Quebec, Canada) was designed to combine improved handling properties compared to standard pressure-wires and to offer extremely reliable pressure recording and transmission due to fiber-optic properties compared to piezo-electric sensors and electrical wires. In vitro assessment showed that OptoWire™ steerability, pushability and torquability properties were closer to regular PCI wires than standard electrical pressure wires. In the First-in-Man O2 study, 60 patients were recruited at 2 centers in Canada. A total of 103 lesions were assessed with the OptoWire™ and OptoMonitor™, 75 lesions at baseline and 28 lesions post-PCI (without disconnection). In all crossed lesions (n = 100, 97%), mean Pd/Pa and FFR could be adequately measured. In 11 cases assessed successively with OptoWire™ and Aegis™ (Abbott Vascular, USA) bland-Altman analysis showed a mean difference of 0.002 ± 0.052 mmHg (p = .91) for Pd/Pa and 0.01 ± 0.06 for FFR calculation (p = .45). There was no device-related complication. Upon these initial results, several design changes aimed to improve overall performance including torquability, stiffness, resistance to kink and pressure drift were completed. CONCLUSION: The novel 0.014" fiber-optic OptoWire™ provides superior wire handling with reduced risk of pressure drift allowing reliable pre- and post-PCI physiology assessment.

Biomechanical characterization of a chronic type a dissected human aorta.

Aortic dissection is one of the most lethal cardiovascular diseases. A chronic Type A (Stanford) dissected aorta was retrieved for research from a 73-year-old male donor without diagnosed genetic disease. The aorta presented a dissection over the full length, and it reached a diameter of 7.7 cm in its ascending portion. The descending thoracic aorta underwent layer-specific quasi-static and dynamic mechanical characterizations after layer separation. Mechanical tests showed a physiological (healthy) behavior of the intima and some mechanical anomalies of the media and the adventitia. In particular, the static stiffness of both these layers at smaller strains was three times smaller than any one measured for twelve healthy aortas. When the viscoelastic properties were tested, adventitia presented a larger relative increase of the dynamic stiffness at 3 Hz with respect to most of the healthy aortas. The loss factor of the adventitia, which is associated with dissipation, was at the lower limit of those measured for healthy aortas. It seems reasonable to attribute these anomalies of the mechanical properties exhibited by the media and the adventitia to the severe remodeling secondary to the chronic nature of the dissection. However, it cannot be excluded that some of the mechanical anomalies were present before remodeling.

Anthropomorphic and biomechanical mockup for abdominal aortic aneurysm.

Abdominal aortic aneurysm (AAA) is an asymptomatic condition due to the dilation of abdominal aorta along with progressive wall degeneration, where rupture of AAA is life-threatening. Failures of AAA endovascular repair (EVAR) reflect our inadequate knowledge about the complex interaction between the aortic wall and medical devices. In this regard, we are presenting a hydrogel-based anthropomorphic mockup (AMM) to better understand the biomechanical constraints during EVAR. By adjusting the cryogenic treatments, we tailored the hydrogel to mimic the mechanical behavior of human AAA wall, thrombus and abdominal fat. A specific molding sequence and a pressurizing system were designed to reproduce the geometrical and diseased characteristics of AAA. A mechanically, anatomically and pathologically realistic AMM for AAA was developed for the first time, EVAR experiments were then performed with and without the surrounding fat. Substantial displacements of the aortic centerlines and vessel expansion were observed in the case without surrounding fat, revealing an essential framework created by the surrounding fat to account for the interactions with medical devices. In conclusion, the importance to consider surrounding tissue for the global deformation of AAA during EVAR was highlighted. Furthermore, potential use of this AMM for medical training was also suggested.

Comparative analysis of calcification parameters with Agatston Score approximations for ex vivo atherosclerotic lesions.

BACKGROUND: The Agatston Calcium Score is a predictor of major adverse cardiovascular events but it is unable to identify high-risk lesions. Recent research suggests that examining calcification phenotype could be more indicative of plaque stability. OBJECTIVE: To examine the Agatston score's ability to determine atherosclerotic calcification phenotype. METHODS: Micro-Computed Tomography was performed on 20 carotid and 20 peripheral lower limb lesions. ImageJ pixel histogram analysis quantified the non-calcified (≥30HU, <130HU) and calcified (≥130HU) tissue volumes. ImageJ '3D Objects Counter' plugin determined the calcified particle count, volumes and maximum attenuation density of each particle. Image stacks were subsequently downsampled to a resolution of 0.7 × 0.7 × 3 mm and an approximation for the Extra-Coronary Calcium Scores (ECCS) were calculated. Spearman's correlation examined the relationships between ECCS approximations and calcification parameters. RESULTS: ECCS has a strong positive correlation with the Calcified Volume Fraction (CVF) (rs = 0.865, p < 0.0005), weak positive correlations with Calcified Particle Fraction (CPF) (rs = 0.422, p = 0.007) and Microcalcification Fraction (micro-CF) (rs = 0.361, p = 0.022). There is no correlation evident between ECCS and Calcified Particle Index (CPI) (rs = -0.162, p = 0.318). It is apparent that there is a high prevalence of microcalcifications in both carotid and peripheral lower limb lesions. Additionally, an inverse relationship exists between calcified particle volume and maximum-recorded attenuation density. CONCLUSION: The density-weighted Agatston calcium scoring methodology needs to be reviewed. Calcium scoring which differentiates between critical calcification morphologies, rather than presenting a density-weighted score, is required to direct high-risk plaques towards tailored treatment.

A manufacturing and annealing protocol to develop a cold-sprayed Fe-316L stainless steel biodegradable stenting material.

Biodegradable stents show promise to revolutionize coronary artery disease treatment. Its successful implementation in the global market remains limited due to the constraints of current generation biodegradable materials. Cold gas dynamic spraying (CGDS) has been proposed as a manufacturing approach to fabricate a metallic biodegradable amalgamate for stent application. Iron and 316L stainless steel powders are combined in a 4:1 ratio to create a novel biomaterial through cold spray. Cold spray processing however, produces a coating in a work hardened state, with limited ductility, which is a critical mechanical property in stent design. To this end, the influence of annealing temperature on the mechanical and corrosion performances of the proposed Fe-316L amalgamate is investigated. It was found that annealing at 1300 °C yielded a complex material microstructure, with an ultimate tensile strength of approximately 280 MPa and ductility of 23%. The static corrosion rate determined at this annealing temperature was equal to 0.22 mg cm-2 day-1, with multiple corrosion species identified within the degradation layers. Precipitates were observed throughout the microstructure, which appeared to accelerate the overall corrosion behaviour. It was shown that cold-sprayed Fe-316L has significant potential to be implemented in a clinical setting. STATEMENT OF SIGNIFICANCE: Biodegradable stents have potential to significantly improve treatment of coronary artery disease by decreasing or potentially eliminating late-term complications, including stent fracture and in-stent restenosis. Current generation polymer biodegradable stents have led to poorer patient outcomes in comparison to drug-eluting stents, however, and it is evident that metallic biomaterials are required, which have increased strength. To this end, a novel iron and stainless steel 316L biomaterial is proposed, fabricated through cold-gas dynamic spraying. This study analyses the effect of annealing on the Fe-316L biomaterial through corrosion, mechanical, and microstructural investigations. The quantitative data presented in this work suggests that Fe-316L, in its annealed condition, has the mechanical and corrosion properties necessary for biodegradable stent application.

Fatigue exhaustion of the mitral valve tissue.

Sudden failure and rupture of the tissue is a rare but serious short-term complication after the mitral valve surgical repair. Excessive cyclic loading on the suture line of the repair can progressively damage the surrounding tissue and finally cause tissue rupture. Moreover, mechanical over-tension, which occurs in a diseased mitral valve, gradually leads to tissue floppiness, mitral annular dilation, and leaflet rupture. In this work, the rupture mechanics of mitral valve is studied by characterizing the fracture toughness exhaustion of healthy tissue. Results of this study show that fracture toughness of the posterior mitral valve is lower than its anterior counterpart, indicating that posterior tissue is more prone to failure. Moreover, the decrease in fracture toughness by increasing the number of fatigue cycles shows that excessive mechanical loading leads to progressive failure and rupture of mitral valve tissue within a damage accumulative process.

A Numerical Preoperative Planning Model to Predict Arterial Deformations in Endovascular Aortic Aneurysm Repair.

Endovascular aneurysm repair is rapidly emerging as the primary preferred method for treating abdominal aortic aneurysm. In this image-guided interventional procedure, to obtain the roadmap and decrease contrast injections, preoperative CT images are overlaid onto live fluoroscopy images using various 2D/3D image fusion techniques. However, the structural changes due to the insertion of stiff tools degrade the fusion accuracy. To correct the mismatch and quantify the intraoperative deformations, we present a patient-specific biomechanical model of the aorto-iliac structure and its surrounding tissues. The predictive capability of the model was evaluated against intraoperative data for a group of four patients. Incorporating the perivascular tissues into the model significantly improved the results and the mean distance between the real and simulated endovascular tools was 2.99 ± 1.78 mm on the ipsilateral side and 4.59 ± 3.25 mm on the contralateral side. Moreover, the distance between the deformed iliac ostia and their corresponding landmarks on intraoperative images was 2.99 ± 2.48 mm.

Transradial experience with bioresorbable vascular scaffolds: A case-matched study with metallic drug-eluting stents.

BACKGROUND: Whether polymeric bioresorbable vascular scaffolds (BVS) implantation with transradial approach is feasible and safe is unknown. We compared the feasibility and safety of the transradial approach for BVS delivery with metallic drug-eluting stents (DES). METHODS: We identified 118 consecutive patients who underwent BVS implantation and we compared 30-days and 1-year results with 118 matched patients with DES. Patients were matched for age, sex, risk factors and clinical indication. RESULTS: Rates of transradial approach were 98% in the BVS group vs 95% in the DES group (P = 0.16) with 5Fr used in 38% and 32% (P = 0.34), respectively. The number of stents was similar in both groups, 2.6 ±â€¯1.5 vs 2.4 ±â€¯1.3 (P = 0.23). Although maximal pressure for stent deployment was identical in both groups (16 ±â€¯3 atm), more lesions were pre-dilated (83% vs 52%, P < 0.001) and post-dilated (71% vs 33%, P < 0.001) in the BVS group. Contrast volume (217 ±â€¯97 vs 175 ±â€¯108 ml, P < 0.001), fluoroscopy time (16 [10-23] vs 13 [8-21] min, P = 0.04) and procedure duration (65 ±â€¯31 vs 56 ±â€¯47 min, P = 0.045) were significantly higher in the BVS group. Major adverse cardiac events, including death, myocardial infarction and target vessel revascularization remained similar in both groups, 1.7% vs 0.8% (P = 0.56) at 30 days and 10% vs 8.5% (P = 0.66) at 1 year. At 1 year, stent thrombosis occurred in 2 (1.7%) patients in the BVS group and 1 (0.8%) patient in the DES group (P = 0.56). CONCLUSION: The use of transradial approach for BVS compared to DES implantation was feasible and safe in all-comers, although BVS implantation included more technical challenges. Outcomes up to 1-year remained comparable in both groups.

3D printing materials and their use in medical education: a review of current technology and trends for the future.

3D printing is a new technology in constant evolution. It has rapidly expanded and is now being used in health education. Patient-specific models with anatomical fidelity created from imaging dataset have the potential to significantly improve the knowledge and skills of a new generation of surgeons. This review outlines five technical steps required to complete a printed model: They include (1) selecting the anatomical area of interest, (2) the creation of the 3D geometry, (3) the optimisation of the file for the printing and the appropriate selection of (4) the 3D printer and (5) materials. All of these steps require time, expertise and money. A thorough understanding of educational needs is therefore essential in order to optimise educational value. At present, most of the available printing materials are rigid and therefore not optimum for flexibility and elasticity unlike biological tissue. We believe that the manipuation and tuning of material properties through the creation of composites and/or blending materials will eventually allow for the creation of patient-specific models which have both anatomical and tissue fidelity.

Fiber-reinforced computational model of the aortic root incorporating thoracic aorta and coronary structures.

Cardiovascular diseases are still the leading causes of death in the developed world. The decline in the mortality associated with circulatory system diseases is accredited to development of new diagnostic and prognostic tools. It is well known that there is an inter relationship between the aortic valve impairment and pathologies of the aorta and coronary vessels. However, due to the limitations of the current tools, the possible link is not fully elucidated. Following our previous model of the aortic root including the coronaries, in this study, we have further developed the global aspect of the model by incorporating the anatomical structure of the thoracic aorta. This model is different from all the previous studies in the sense that inclusion of the coronary structures and thoracic aorta into the natural aortic valve introduces the notion of globality into the model enabling us to explore the possible link between the regional pathologies. The developed model was first validated using the available data in the literature under physiological conditions. Then, to provide a support for the possible association between the localized cardiovascular pathologies and global variations in hemodynamic conditions, we simulated the model for two pathological conditions including moderate and severe aortic valve stenoses. The findings revealed that malformations of the aortic valve are associated with development of low wall shear stress regions and helical blood flow in thoracic aorta that are considered major contributors to aortic pathologies.

Effect of stenosis eccentricity on the functionality of coronary bifurcation lesions-a numerical study.

Interventional cardiologists still rely heavily on angiography for the evaluation of coronary lesion severity, despite its poor correlation with the presence of ischemia. In order to improve the accuracy of the current diagnostic procedures, an understanding of the relative influence of geometric characteristics on the induction of ischemia is required. This idea is especially important for coronary bifurcation lesions (CBLs), whose treatment is complex and is associated with high rates of peri- and post-procedural clinical events. Overall, it is unclear which geometric and morphological parameters of CBLs influence the onset of ischemia. More specifically, the effect of stenosis eccentricity is unknown. Computational fluid dynamic simulations, under a geometric multiscale framework, were executed for seven CBL configurations within the left main coronary artery bifurcation. Both concentric and eccentric stenosis profiles of mild to severe constriction were considered. By using a geometric multiscale framework, the fractional flow reserve, which is the gold-standard clinical diagnostic index, could be calculated and was compared between the eccentric and concentric profiles for each case. The results suggested that for configurations where the supplying vessel is stenosed, eccentricity could have a notable effect on and therefore be an important factor that influences configuration functionality.

The impact of the aortic valve impairment on the distant coronary arteries hemodynamics: a fluid-structure interaction study.

Atherosclerosis is still the leading cause of death in the developed world. Although its initiation and progression is a complex multifactorial process, it is well known that blood flow-induced wall shear stress (WSS) is an important factor involved in early atherosclerotic plaque initiation. In recent clinical studies, it was established that the regional pathologies of the aortic valve can be involved in the formation of atherosclerotic plaques. However, the impact of hemodynamic effects is not yet fully elucidated for disease initiation and progression. In this study, our developed 3D global fluid-structure interaction model of the aortic root incorporating coronary arteries is used to investigate the possible interaction between coronary arteries and aortic valve pathologies. The coronary hemodynamics was examined and quantified for different degrees of aortic stenosis varying from nonexistent to severe. For the simulated healthy model, the calculated WSS varied between 0.41 and 1.34 Pa which is in the atheroprotective range. However, for moderate and severe aortic stenoses, wide regions of the coronary structures, especially the proximal sections around the first bifurcation, were exposed to lower values of WSS and therefore they were prone to atherosclerosis even in the case of healthy coronary arteries.

Loss of mechanical directional dependency of the ascending aorta with severe medial degeneration.

Biomechanical characterization of the aortic wall may help risk stratify patients with aneurysms. We investigated the degree of anisotropy, the directional dependency of mechanical properties, in control and aneurysmal ascending aortic tissue. We hypothesized that medial degeneration and aortic wall remodeling as found in aneurysmal tissue alter energy loss in both the circumferential and longitudinal directions, thereby reducing anisotropy. Aneurysmal and control ascending aortic tissue excised during surgery was subjected to biaxial tensile testing. Stress-strain relationships were collected in the circumferential and longitudinal directions; from these data, the mechanical properties of energy loss and the apparent modulus of elasticity were derived, and the associated anisotropy indices were calculated. Movat pentachrome histological staining was performed, and aortic wall medial degeneration was quantified. Energy loss was greater in the circumferential than the longitudinal direction, demonstrating significant anisotropy in both normal and aneurysmal aortas (P<.0001). This directional dependency diminished in (a) larger aortas (r2=0.15, P=.01), especially when indexed to body surface area (r2=0.29, P=.002); (b) aortas with greater overall energy loss (r2=0.44, P<.0001); (3) aortas associated with tricuspid valves (P=.004); and (4) higher collagen-to-elastin ratio (r2=0.29, P=.001). Aortas with collagen-to-elastin ratios greater than 2 were uniformly isotropic. Furthermore, the greatest energy loss anisotropy was found on the inner curvature of the aorta (P=.01). Energy loss demonstrates the directional dependency of aortic tissue. Energy loss isotropy is associated with medial degeneration, indicating that microstructural changes can be captured by global biomechanics, thereby identifying it as a marker of disease severity.

3D physiological model of the aortic valve incorporating small coronary arteries.

The diseases of the coronary arteries and the aortic root are still the leading causes of mortality and morbidity worldwide. In this study, a 3D global fluid-structure interaction of the aortic root with inclusion of anatomically inspired small coronary arteries using the finite element method is presented. This innovative model allows to study the impact and interaction of root biomechanics on coronary hemodynamics and brings a new understanding to small coronary vessels hemodynamics. For the first time, the velocity profiles and shear stresses are reported in distal coronary arteries as a result of the aortic flow conditions in a global fluid-structure interaction model.

Evaluating ascending aortic aneurysm tissue toughness: Dependence on collagen and elastin contents.

Ascending thoracic aortic aneurysms (ATAAs) can lead to a dissection or rupture of the aorta, causing death or disability of the patients. Surgical interventions used to treat this disease are associated with risks of mortality and morbidity. Several studies have investigated the rupture mechanisms of ATAAs; however, underlying reasons behind aortic rupture (failure) have not been fully elucidated and further investigations are necessary. The rupture of pathological aortic tissue is a local phenomenon resulting from defects or tears in the vessel wall. In this work, the toughness-based rupture properties of ATAAs have been examined. The toughness, biaxial tensile properties, and histological properties of aneurysmal and control human ascending thoracic aortas (ATAs) were characterized from four quadrants of surgically excised aortic rings. The aneurysmal tissue population included aortas from patients with bicuspid aortic valves (BAV) and tricuspid aortic valves (TAV). The toughness, incremental modulus, and thickness properties of the aortas were determined and compared regionally. Additionally, to further explore the rupture propensity of ATAAs, the inter-correlation of the toughness properties with histological characteristics have been explored. We found no correlation between toughness and incremental modulus. However, toughness decreased significantly with the amount of collagen. In the outer curvature, there was an increase in incremental modulus with collagen+elastin content, but a decrease in toughness. These results suggest tissue remodeling could affect toughness and stiffness differently in ascending aortic aneurysms.