Search Results (161)

The Myval balloon-expandable transcatheter heart valve was developed for transcatheter aortic valve implantation, but its broad 20–32 mm size matrix and controlled deployment have prompted use in non-aortic landing zones. This narrative review critically synthesizes Myval-specific case reports, case series, and observational cohorts, together with relevant platform-level evidence, addressing device design, anatomical selection, imaging, procedural strategy, clinical outcomes, and evidence gaps. Reported applications include mitral valve-in-valve, valve-in-ring, and valve-in-mitral annular calcification; tricuspid valve-in-valve and valve-in-ring; and pulmonary implantation in conduits, surgical bioprostheses, and selected native or patched right ventricular outflow tracts. Outcomes appear most predictable within circular stented surgical bioprostheses, whereas non-circular rings, severe mitral annular calcification, and compliant or aneurysmal outflow tracts present greater risks of inadequate anchoring, paravalvular regurgitation, embolization, frame deformation, left ventricular outflow tract obstruction, and coronary compression. Intermediate and extra-large diameters increase the available nominal sizing options; however, no clinical evidence demonstrates that this reduces embolization, paravalvular regurgitation, residual gradients, or reintervention. The available data document procedural feasibility in anatomically selected patients but are predominantly observational, with limited independent adjudication and follow-up. These procedures are generally off-label and should remain individualized Heart Team decisions; prospective multicenter studies are required to define comparative safety, antithrombotic management, durability, and lifetime reintervention strategies. Full article

Methanol compression-ignition engines are vital for transport carbon neutrality, yet methanol’s low cetane number, corrosivity, low viscosity, and cavitation tendency compromised piezoelectric injector reliability. This study proposed systematic optimization strategies tailored to methanol’s fuel properties. A sealed thin-walled metal encapsulation, fabricated from precipitation-hardening martensitic stainless steel, was designed to isolate corrosive methanol media. The geometry of the tubular spring was optimized to meet the stiffness requirements for high-frequency injections. A monolithic nozzle without side pin holes, also upgraded to the same precipitation-hardening martensitic stainless steel, effectively suppressed stress corrosion cracking by leveraging the material’s combined high strength and excellent corrosion resistance. A dedicated return-line backpressure valve compensated for hydraulic leakage and improved fuel replenishment, and nozzle hole taper and inlet fillet radius were optimized to mitigate cavitation. Cold-motoring reliability tests showed the optimized injector maintained flow deviation within 3% after 100 million cycles, whereas the unoptimized prototype reached 8% deviation at 60 million cycles. The single-cycle injected fuel quantity coefficient of variation dropped from 4% to 1.3%. Spray characteristic comparison tests further confirmed that the optimized injector maintained stable flow consistency and atomization quality after prolonged cyclic operation. These optimizations effectively resolved corrosion, wear, and hydraulic instability caused by methanol, significantly enhancing flow consistency and durability over the service life. The results provided critical component-level technical support for advancing methanol compression-ignition engines from laboratory research to industrial application, addressing key reliability barriers that previously hindered engineering deployment of methanol-fueled powertrains. Full article

In response to common issues with traditional automotive switches, such as poor contact of terminals, low durability, and weak vibration resistance, this paper proposes and designs a novel high-performance automotive toggle switch. Through structural design and parameter optimization, a new solution is provided to enhance the structural strength and service life of automotive electronic components. After completing three-dimensional modeling based on SolidWorks 2025, a full set of simulation analyses was carried out using ANSYS Workbench 2024 R2. After structural optimization, the maximum stress of the core valve stem decreased from 17.19 MPa to 14.877 MPa, a reduction of 13.5%; meanwhile, the fatigue life increased to 2.51 times that before optimization, indicating that for polycarbonate materials, a slight reduction in stress can significantly slow the rate of component damage accumulation. The switch’s first-order natural frequency is 1171.7 Hz, and a random vibration analysis of the switch was conducted according to the industry standard ISO 16750-3:2023. Under excitations covering the entire 2000 Hz frequency range, the switch structure did not show deformation or fatigue risks caused by resonance, indirectly confirming that vibration energy density is often more concentrated at low frequencies. This study not only completes the innovative design and performance verification of the novel toggle switch but also demonstrates that the comprehensive research methods employed provide a systematic analytical approach for developing high-performance, highly reliable automotive electronic components under stringent industry standards. Full article

Flexible graphite packing rings are widely employed in high-temperature and high-pressure valve sealing systems owing to their intrinsic lubricity and thermal stability, yet their service reliability is often compromised by low mechanical strength, pronounced creep, and unstable tribological behavior under extreme conditions. Here, we present an interface-engineered strategy to enhance the service performance of graphite packing rings via reinforcement with surface-functionalized PAN-based carbon fibers (PAN-CFs; carbonized fibers derived from polyacrylonitrile precursors). Through controlled oxidative modification of carbon fibers combined with high-temperature graphite expansion, a three-dimensional reinforced graphite network with uniform fiber dispersion was constructed. The influence of PAN-based carbon fiber (PAN-CF) content (0–7 wt%) on compressive strength, thermal stability, friction behavior, and long-term durability was systematically evaluated. An optimal performance was achieved at 5 wt% PAN-CF, featuring a ~58% increase in compressive strength, a stable friction coefficient of 0.15–0.18, and enhanced creep resistance, while retaining over 78% of the initial strength after 1000 h of sustained loading. Microstructural and complementary structural analyses suggest that these improvements are associated with interfacial mechanical anchoring, fiber embedding, and load-transfer reinforcement enabled by fiber surface functionalization and the expanded graphite architecture. This work offers a practical material-level approach to improving the long-term reliability of graphite-based sealing components in demanding industrial environments. Full article

Background: Current ESC/EACTS guidelines recommend bioprosthetic valves for aortic valve replacement (AVR) in patients > 65 years, yet their use is increasing among younger individuals. The INSPIRIS Resilia (IR) valve, a next-generation bioprosthesis, was designed to improve durability and reduce structural valve degeneration (SVD). This study compares clinical and valve-related outcomes up to six years in patients undergoing AVR with either the IR or its predecessor, the Perimount Magna Ease (PME) valve. Methods: Between January 2017 and December 2023, 2053 patients underwent isolated or combined AVR at a single institution (1602 PME; 451 IR). Propensity-score matching identified 224 patient pairs with comparable baseline characteristics. Outcomes were assessed over follow-up extending up to six years, focusing on cardiovascular and valve-related adverse events. Transvalvular gradients were also assessed at follow-up. Results: After matching, mean age was 64.2 ± 7.7 years in both groups. Freedom from cardiovascular mortality at six years was similar between PME and IR (96.6% vs. 98.2%; p = 0.34), as were rates of stroke, rehospitalization, prosthetic valve endocarditis, and reintervention. A total of 12 PME (5.4%) and six IR valves (2.5%) were explanted during follow-up (p = 0.15), with prosthetic endocarditis representing the leading cause of reintervention. Only one case of severe SVD was observed in both groups. Conclusions: In patients undergoing AVR with comparable baseline risk profiles, IR and PME valves demonstrated similar clinical, valve-related, and hemodynamic outcomes up to six years of follow-up. Prosthetic valve endocarditis represented the leading cause of valve failure, whereas structural valve deterioration remained rare. Longer follow-up and a greater number of valve-related events will be necessary to determine whether differences in bioprosthetic valve degeneration emerge over time. Full article

Background/Objectives: The Ross procedure is recognized for its excellent long-term outcomes in aortic valve surgery, providing superior hemodynamic performance, freedom from anticoagulation, and a low risk of valve thrombosis. The aim of this study was to evaluate the technical feasibility and early clinical outcomes of performing the Ross procedure through a minimally invasive V-shaped (arrow-shaped) partial sternotomy in adult patients. Methods: Eleven consecutive adult patients underwent a Ross procedure through a 7 cm upper midline skin incision and a V-shaped (arrow-shaped) ministernotomy sternotomy extending to the third intercostal space. Cardiopulmonary bypass was established through central cannulation. The pulmonary autograft was implanted in the aortic position using the miniroot technique, followed by implantation of a pulmonary homograft in the pulmonary position. Operative, perioperative, and early echocardiographic outcomes were prospectively evaluated. Results: All procedures were completed successfully without conversion to full sternotomy or major intraoperative complications. The cardiopulmonary bypass and aortic cross-clamp times were consistent across the series, averaging 144 and 86 min, respectively. Intraoperative transesophageal echocardiography confirmed satisfactory function of both the autograft and homograft in all patients. Postoperative recovery was uneventful, with mechanical ventilation times ranging from 4 to 8 h and intensive care unit stays of 24–48 h. No cases of stroke, renal failure, permanent pacemaker implantation, atrial fibrillation, wound infection, sternal instability, reoperation for bleeding, readmission, or mortality occurred. Patients were discharged between postoperative days 7 and 10. At 3-month follow-up, transthoracic echocardiography demonstrated preserved left ventricular function, absence of aortic regurgitation, and low transvalvular gradients in all patients. Conclusions: This initial single-center case series demonstrates the technical feasibility of performing the Ross procedure through a V-shaped (arrow-shaped) partial sternotomy in carefully selected adult patients. The approach provides satisfactory operative exposure for all components of the procedure while maintaining the advantages of minimally invasive surgery. Larger studies with longer follow-up are required to further evaluate clinical outcomes and long-term durability. Full article

Transcatheter Aortic Valve Implantation/Replacement (TAVI/TAVR) has come a long way since the first-in-human implant by Prof Cribier & colleagues in 2002. Initially a consideration for inoperable/high-surgical-risk patients, TAVI is now indicated in patients with severe tricuspid aortic stenosis and suitable anatomy aged 70 or higher. This has been made possible due to improvements in preprocedural planning, performance upgrades to and evolution of transcatheter heart valve (THV) systems and increasing operator experience. Younger age at index implantation, complexities of redo TAVI planning and methods to improve THV durability are the next frontiers. This review summarizes these advancements while emphasizing preprocedural planning, current guidelines, and individualized device selection, with a brief note on polymeric heart valves—developed to overcome the disadvantageous bioprosthetic dysfunction seen with current THVs. Full article

Introduction: Transcatheter aortic valve replacement (TAVR) has become the predominant treatment for severe aortic stenosis across all surgical risk categories. However, its role in patients aged 65 years and younger remains uncertain, and current guideline recommendations continue to favor surgical aortic valve replacement (SAVR) in this population. Despite this, contemporary real-world data demonstrate a marked increase in TAVR utilization among younger patients, creating an important gap between guidelines and clinical practice. Methods: This review synthesizes contemporary observational evidence evaluating TAVR in patients ≤65 years, with a focus on patient selection, clinical outcomes, and lifetime management considerations. Results: Available studies demonstrate that younger patients undergoing TAVR often represent a highly selected and clinically complex population with greater comorbidity burden, higher surgical risk, and shorter life expectancy than age-matched SAVR recipients, yet substantial hospital-level variation in TAVR utilization exists even after risk adjustment. Mid-term observational data suggest higher mortality and heart failure readmission rates following TAVR compared with SAVR, although these findings are likely influenced by substantial baseline differences between treatment groups. No randomized controlled trial has specifically compared TAVR and SAVR in patients ≤65 years. Furthermore, long-term issues including valve durability, coronary access, redo-TAVR feasibility, and THV optimization remain incompletely understood. Conclusions: TAVR recipients ≤65 are often a clinically distinct group characterized by significantly heavier comorbidity burdens than SAVR recipients of the same age with standard surgical risk models possibly underestimating the true clinical risk. Despite this, significant hospital-level variation in TAVR utilization persists even after risk adjustment, suggesting that institutional practice patterns and other non-clinical factors continue to influence treatment selection. Full article

The advent of transcatheter aortic valve implantation (TAVI) has redefined the treatment of aortic stenosis over the last two decades, evolving from a therapy reserved for patients that were deemed to be of prohibitive surgical risk to the standard of care for a large group of patients presenting with symptomatic disease. With improvements in technology, operator and institutional experience and longer-term outcome data, recent guidelines have supported the broadening of indications to low-risk and asymptomatic patients in addition to other pathologies including the management of failed surgical bioprosthetic valves and aortic regurgitation. The rapid developments in the field have resulted in a rapid expansion of TAVI. The focus has moved from the technical aspects of the procedure itself that are now well established to the lifetime management of patients with aortic stenosis, particularly younger patients with regard to valve durability, planning for a further intervention after TAVI and associated considerations including future coronary access. Beyond aortic stenosis, TAVI technology is also increasingly being utilized for the management of failed surgical bioprostheses, bicuspid valve disease, aortic incompetence and mitral/tricuspid disease and these represent future areas of focus in the field. Full article

Aortic stenosis is predominantly treated through transcatheter bioprosthetic heart valve implantation. However, the materials used in these devices are prone to premature failure. Polymer heart valves provide an alternative to current commercial devices, offering materials with greater durability and customisation through fibre reinforcement. Given the wide range of available materials and structures, there is a need for a systematic and efficient approach to designing and optimising novel bioinspired polymeric leaflets. This work presents a framework that employs computational modelling and Design of Experiments (DOE) tools to optimise bioinspired, 3D-printed, fibre-reinforced polymer leaflets made using melt electrowriting (MEW). Here, finite element (FE) models are created to represent MEW fibre-reinforced polymer leaflets for application in a transcatheter aortic heart valve. The behaviour of this valve under physiological loading conditions is modelled to predict valve performance and leaflet material response. These models were first used to investigate the impact of fibre orientation on valve performance and leaflet response, thereby demonstrating the benefits of a bioinspired fibre reinforcement structure. Using a DOE approach, the structural combination of MEW fibre reinforcement and an elastomeric matrix was optimised to improve valve performance and reduce leaflet stress and strain. Overall, the framework offers an efficient and versatile methodology for optimising fibre-reinforced polymer leaflets using an in silico approach, thereby reducing the need for physical prototyping and testing of these next-generation devices during early product development. Full article

Paravalvular leak (PVL) is a clinically important complication of surgical prosthetic valve replacement that may lead to heart failure, hemolytic anemia, and repeat intervention. Transcatheter closure has become an accepted alternative to redo surgery in selected high-risk patients, with Amplatzer devices serving as a widely used platform because of their versatility across irregular and crescentic defects. This narrative review summarizes contemporary evidence on the role of Amplatzer-based devices in PVL closure, with an emphasis on device design, imaging-guided procedural strategies, clinical outcomes, safety, comparison with alternative occlusion systems, and future directions. Available data from registries, cohort studies, and comparative observational series indicate high technical success, meaningful improvement in symptoms and hemolysis-related burden, and acceptable medium-term durability in appropriately selected patients. Outcomes, however, remain strongly influenced by leak morphology, prosthetic valve characteristics, access route, imaging quality, and operator experience. Important limitations of the current evidence include the absence of randomized trials, nonuniform endpoint definitions, heterogeneous imaging protocols, and limited long-term comparative durability data. In contemporary structural heart practice, Amplatzer devices remain a widely used and practical platform for transcatheter PVL repair, particularly in experienced centers managing anatomically complex leaks. Full article

Understanding the mechanical behavior of valve materials and the hemodynamic characteristics of blood flow is important for improving prosthetic heart valve design. In this study, a comprehensive computational investigation was conducted to evaluate the biomechanical and hemodynamic behavior of a three-dimensional tricuspid valve model constructed from reported prosthetic valve geometries. The structural response of the valve was evaluated using linear elastic, viscoelastic, and hyperelastic constitutive models for four different materials: pyrolytic carbon, polyurethane, porcine tissue, and bovine tissue. The results demonstrated clear material-dependent trends. Pyrolytic carbon exhibited negligible deformation (1.7166 × 10⁻⁸ m), confirming its rigid mechanical behavior, whereas biological tissues showed greater compliance, with the largest deformation observed for the bovine hyperelastic model (9.6837 × 10⁻⁵ m). Hyperelastic tissue models produced lower peak von Mises stresses (1.3951 × 10⁴–1.8603 × 10⁴ Pa) than the corresponding linear elastic tissue models (2.6842 × 10⁴–2.7017 × 10⁴ Pa), indicating improved stress redistribution under nonlinear deformation. Polyurethane showed intermediate mechanical behavior, with moderate deformation and lower stress under viscoelastic modeling than under the linear elastic assumption, suggesting its potential as a polymeric alternative to traditional valve materials. The Computational Fluid Dynamics (CFD) analysis of the rigid open valve geometry revealed a central velocity jet with a peak velocity of approximately 0.092 m/s, localized vortex formation with a maximum vorticity magnitude of about 177 s⁻¹ and a peak instantaneous wall shear stress of 1.32 Pa near the leaflet edges and valve opening. Overall, the results highlight the trade-off between rigidity, compliance, and durability among prosthetic valve materials and suggest that polyurethane may provide a balanced alternative for tricuspid valve replacement. Full article

Background: Mitral regurgitation due to Barlow’s disease remains surgically demanding. Despite widespread experience, consensus is lacking on whether the Alfieri repair can serve as a deliberate and durable rather than a rescue strategy in this complex pathology. Methods: We retrospectively analyzed patients undergoing mitral valve repair due to severe mitral regurgitation resulting from Barlow’s disease using either the Alfieri or Neochordae repair techniques. Patients received a uniform semi–rigid annuloplasty ring, while leaflet resection and concomitant coronary or aortic procedures were excluded. Results: Baseline demographics and echocardiography were broadly comparable. Perioperative mortality was 0% in both cohorts, with similarly low rates of major complications. Aortic cross–clamp time was significantly shorter with Alfieri repair (p < 0.001). No relevant postoperative transmitral gradient or systolic anterior motion occurred. At a mean follow–up of 4.2 years, more–than–moderate MR was observed in one patient per group (Alfieri 2.4% vs. Neochordae 1.2%). At 10 years, the cumulative incidence of more–than–moderate mitral regurgitation and redo mitral surgery was similarly low between techniques (p = 0.810 and p = 0.460). Most patients were NYHA class I–II at last follow–up, demonstrating improved functional status. Echocardiography showed left ventricular reverse remodeling without intergroup differences. Conclusions: These data indicate that the Alfieri approach provides durable competence and hemodynamic safety comparable to the Neochordae technique while reducing cross–clamp time, supporting its use as a deliberate strategy rather than a bailout in anatomically suitable valves. Full article

Background: Annuloplasty is a key component of mitral valve repair, yet the impact of ring design on early outcomes remains unclear. Methods: This retrospective study included 153 consecutive patients undergoing mitral valve repair with annuloplasty. Ring designs were grouped into semi-rigid rings, semi-rigid bands, rigid rings, and other designs. The primary outcome was new-onset postoperative atrial fibrillation (AF). Secondary outcomes included early complications and repair durability based on follow-up echocardiography. Results: Postoperative AF occurred in 14.4% of patients and did not differ across ring design groups (p = 0.791). No independent predictors of AF were identified, although a longer aortic cross-clamp time showed a borderline association. Early outcomes were favorable, with 2.0% mortality and 5.9% rethoracotomy. Follow-up echocardiography was available in 79.7% of patients, with good or moderate repair observed in 95.9%. Echocardiographic repair failure occurred in 2.5% of patients. No clear association was observed between ring design and repair durability. Conclusions: In this real-world cohort, no significant association was detected between annuloplasty ring design and early postoperative AF or short-term outcomes. These findings should be interpreted cautiously, given the low event rate and small subgroup sizes. Full article

Transcatheter Aortic Valve Replacement (TAVR) has transformed aortic stenosis management across the full risk spectrum, but expansion into younger populations makes valve failure and reintervention central to lifetime planning. There are two pathways to follow when TAVR fails: redo transcatheter implantation and surgical explantation with surgical aortic valve replacement (SAVR), termed TAVR-SAVR. This narrative review synthesizes evidence from four studies (35,677 patients, 2011–2024) examining the association between prior valve type and redo SAVR outcomes versus redo SAVR after prior surgical prosthesis (SAVR-SAVR). TAVR-SAVR volume grew at up to 144.6% annually, projected to surpass SAVR-SAVR by approximately 2029 based on linear extrapolation from limited registry and single-center data. Operative mortality was 12.3–17% in TAVR-SAVR versus 1.1–9% in SAVR-SAVR, persisting after propensity matching in both comparative studies (11.3% vs. 6.7%, OR 1.7; and 12.0% vs. 1.1%, OR 12.5). Observed-to-expected mortality ratios exceeded 1.0 across all risk strata, including low-risk patients (O/E up to 5.48), while SAVR-SAVR demonstrated a remarkably low ratio of 0.22–0.33. Renal failure, failure to rescue, and prolonged ventilation were significantly higher following TAVR-SAVR; stroke and pacemaker rates were comparable. Paradoxically, shorter bypass and cross-clamp times in TAVR-SAVR despite worse outcomes are consistent with cumulative organ injury, rather than operative complexity, as a predominant contributor to excess mortality, though this mechanistic explanation remains hypothetical. STS risk models, developed for standard surgical populations, showed limited applicability in this population, with observed mortality consistently exceeding predicted values. These findings raise important considerations regarding TAVR-first strategies in operable patients aged 65–80 years, although causality cannot be established from observational data alone. In the era of expanding TAVR indications, the legacy of the first valve cannot be ignored. Full article