Conventional Valve Research Articles

A Protocol Investigation Comparing Transcatheter Repair with the Standard Surgical Procedure for Secondary Mitral Regurgitation

Background: Secondary mitral regurgitation (SMR) is characterized by a pathological process impacting the left ventricle (LV) as opposed to the mitral valve (MV). In the absence of structural alterations to the MV, the expansion of the LV or impairment of the papillary muscles (PMs) may ensue. A number of technical procedures are accessible for the purpose of determining the optimal resolution for MR. Nevertheless, there is a dearth of rigorous data to facilitate a comparative analysis of MV replacement, MV repair (including subvalvular repair), and transcatheter mitral valve interventions (TMV-Is). The objective of this investigation is to evaluate and compare the efficacy and clinical outcomes of transcatheter mitral valve repair (TMV-r) utilizing the edge-to-edge mitral valve repair (TEER) procedure in comparison to conventional surgical mitral valve interventions (S-SMVis) in patients with secondary mitral regurgitation. Methods and analysis: A consortium of five cardiac surgery institutions from four European states and Japan have joined forces to establish a multicenter observational registry, designated TEERMISO. Patients who underwent technical procedures for SMR between January 2007 and December 2023 will be enrolled consecutively into the TEERMISO registry. The investigation team evaluated the comparative efficacy of replacement and repair techniques, utilizing both the standard surgical methodology and the transcatheter intervention. The primary clinical outcome will be the degree of left ventricular remodeling, as assessed by the left ventricular end-diastolic volume index, at 10 years. The forthcoming research will assess a variety of secondary endpoints, among which all-cause mortality will be the primary endpoint. Subsequent assessments will be made in the following order: functional status, hospitalization, neurocognition, physiological measures (echocardiographic assessment), occurrence of adverse clinical incidents, and reoperation. Ethics and dissemination: The multicenter design of the database is anticipated to reduce the potential for bias associated with institutional caseload and surgical experience. All participating centers possess an established mitral valve protocol that facilitates comprehensive follow-up and management of any delayed mitral complications following replacement surgery or surgical repair of the secondary mitral regurgitation. The data collected will provide insights into the impact of diverse surgical approaches on standard mitral valve surgery and TEER. This will facilitate the evaluation of LV remodeling over the course of long-term post-procedural follow-up. Trial Registration: ClinicalTrials.gov ID: NCT05090540; IRB ID: 202201143

Full linearization of nonlinear flow control valves via variable gear ratio design

The paper proposes the full linearization of nonlinear characteristics of flow control valves via variable gear ratio design. The inherent nonlinear function of the normalized valve capacity coefficients to the percentages of valve opening is derived from flow experiments. In analysis, it is found that the derivative of the inverse function is the reciprocal of the gear ratio, which is used to generate the corresponding driving/driven gear profiles. The rotation of the driven stem of the flow control valve from a driving knob is altered by the variable gear ratio to achieve fully linearized flow characteristics. The experimental results confirm the fully linearized characteristics of a conventional nonlinear flow control valve with correlation to the linearity with R-squared = 0.9984.

Performance analysis and improvement of a novel reed valve in compressors using fluid–structure interaction method

The reed valves used as suction valves in reciprocating compressors are more susceptible to damage due to the limitation of the lift limiter which can't completely block the entire valve plate. This article proposed a novel reed valve featuring a redesigned shape aimed to solve this issue. Compared to conventional reed valves, the proposed valve could effectively mitigate the highest stress occurring at the root of the suction valve. To thoroughly investigate the characteristics of this valve type and improve its performance, a three-dimensional fluid–structure interaction (FSI) model was established and validated using experiments. The leakage through the valve gap in the FSI model was solved using a combination of user-defined function (UDF) and Scheme file in Fluent. Based on this FSI model, the dynamic characteristics and stress distribution of the valve were mainly analyzed. The effect of the lift limiter on the performance of the valve was analyzed, and a suitable lift was determined. Moreover, the influence of thickness and shape parameters, was also analyzed and an efficient improved scheme was subsequently proposed. Through this scheme, the maximum stress of the valve was reduced by 23.77% compared with that of the original valves. This article provides important information for the design and optimization of complex-shaped reed valves.

Clinical Outcomes and Costs of Robotic-assisted versus Conventional Mitral Valve Repair: A National Analysis

Robotic approaches have been increasingly utilized for cardiothoracic operations, though concerns regarding costs remain. We evaluated short-term outcomes and costs of robotic-assisted and conventional mitral valve repair (MV-repair), hypothesizing that cost differences would be mitigated at high-volume programs. Adults undergoing elective MV-repair from 2016 to 2020 were identified in the Nationwide Readmissions Database. Patients with rheumatic heart disease, mitral stenosis, and those undergoing concomitant operations were excluded. Generalized linear models were utilized to evaluate the association between approach and in-hospital mortality, complications, length of stay, costs, and 90-day readmissions. Annual institutional MV-repair volume was modeled using restricted cubic splines, and cost differences subsequently evaluated by volume tertile. Of 40,738 patients, 9.8% underwent robotic-assisted MV-repair. Risk-adjusted outcomes including mortality, stroke, reoperation, respiratory complications, postoperative infection, and readmission were comparable between the two groups, while those undergoing robotic-assisted MV-repair had lower rates of non-home discharge. The median cost of robotic-assisted MV-repair was greater than conventional surgery ($46,800 vs $38,500, p<0.001). Despite a 1.3-day decrement (95% CI 1.1-1.6) in length of stay, robotic-assisted MV-repair was associated with greater risk-adjusted costs by $10,500 (95% CI 5,800-15,200). Programs in the highest volume tertile exhibited comparable costs for robotic-assisted and conventional MV-repair (cost difference $5,900, 95% CI -1,200-12,200, p>0.05). Robotic-assisted MV-repair had comparable short-term outcomes relative to conventional surgery. Despite increased costs of robotic-assisted MV-repair overall, high-volume programs had similar risk-adjusted costs by approach. These findings support the designation and performance of robotic MV-repair at centers of excellence in the United States.

Energy-saving, high-pressure resistant mini valve based on a bistable electromagnetic actuator

As core components of microfluidic and wearable pneumatic electronic systems, mini valves are attracting a growing intellectual interest. However, most existing mini valves exhibit either excessive energy consumption or limited flow rate and holding pressure. To address these issues, this study proposes an energy-saving mini valve with large flow rate and high holding pressure. The implementation of electromagnetic bistable structure allows the valve to remain open or closed without energy consumption. In contrast to the small and intricate flow channels seen in conventional mini valves, the straight-through flow channel design with reduced flow resistance improves its flow rate properties. And the pressure resistance characteristics are enhanced by the use of permanent magnetic attraction for sealing. Furthermore, the valve is driven by a single coil to switch between two steady states, resulting in a more compact structure. We have developed valve prototypes with diameters of 10 mm and 6 mm. Performance evaluation tests have shown that it sustains a holding pressure as high as 100 kPa and a flow rate of 1.5 L/min (@ 3 kPa), while only expending an energy of 0.37 J during switch transitions. Given these attributes, this valve demonstrates significant potential for integration within wearable pneumatic electronic systems.

A peristaltic electromagnetic (EM) micropump with dome-shaped PDMS membranes for biomedical application

A peristaltic electromagnetic (EM) micropump driven by dome-shaped membranes was successfully fabricated and tested. The pump system comprises EM coil components, three magneto-mechanical actuators, and a microfluidic system. The pump system with three actuator membranes/chambers connected in series is intended to replace the conventional valve and pump rollers, enabling the delivery of fluids at a high flowrate. The actuator membrane is made of polydimethylsiloxane (PDMS), measuring 5 mm in diameter and approximately 100 µm thick, and fabricated using soft lithography techniques to form a normally deflected dome-shaped membrane structure. The microfluidic channel is made of PDMS and created using a sacrificial layer-pattern process, allowing straightforward soft-litography process without mold transfer. The fabricated device was tested by applying electrical DC currents ranging from 500 mA to 1000 mA at frequencies up to 10 Hz. This resulted in the depletion of the membrane by up to 2 mm, causing fluid flow through the microchannel at a flow rate of 8 mL per minute. The test results revealed that the peristaltic EM micropump can generate a significant fluid flow rate, making it suitable for pumping controlled fluids within a range of up to 10 mL/minute. This micropump has a wide range of potential applications, including the management of insulin medication for patients with acute diabetes mellitus and the delivery of drugs and dialysate fluid in artificial kidney applications.

TCT-898 Comparison of Procedural Characteristics Between Use of the Savvy Wire for Simultaneous Ventricular Pacing, Aortic Valve Delivery and Hemodynamic Assessment to Conventional Transvenous Ventricular Pacing and Valve Delivery in Patients Undergoing Transcatheter Aortic Valve Replacement

TCT-898 Comparison of Procedural Characteristics Between Use of the Savvy Wire for Simultaneous Ventricular Pacing, Aortic Valve Delivery and Hemodynamic Assessment to Conventional Transvenous Ventricular Pacing and Valve Delivery in Patients Undergoing Transcatheter Aortic Valve Replacement

Research and Application of Flexible Fracturing Manifold in Volumetric fracturing

Abstract In order to solve the problems of high pressure pipe valves in Volumetrictric fracturing, such as large demand of high pressure pipe and valve parts, high pressure manifold for fracturing complex connection, fracturing pipeline connections are complex, long fracturing construction preparation period. The economy and timeliness of pipeline connection seriously affect the speed and efficiency of Volumetrictric fracturing operations. This paper designed and developed the high pressure flexible composite pipe and carried out its performance evaluation test. Combined with Volumetrictric fracturing operation conditions, supporting functional modular manifold system, overcome flexible pipeline and rigid pipeline fast connection technology, flexible fracturing manifold system was formed. Through the large-scale field application in the unconventional reservoir Volumetric fracturing field, The flexible fracturing manifold is compared with the conventional high-pressure pipe valve connection and the single pipe universal connection, the flexible fracturing manifold can reduce the use of high-pressure pipe valves by 1/3, increase the efficiency of fracturing manifold connection by 50%, and reduce the labor intensity by 50%, enables efficient, reduce high pressure manifold connection points by 70%. The timeliness and safety of fracturing manifold connections have been greatly improved. Flexible fracturing manifold fundamentally change the connection mode of Volumetrictric fracturing high-pressure manifold, and realizes the speed and efficiency of reservoir transformation.

Experimental performance comparison of various expansion devices for small-capacity subcritical R744 vapour-compression refrigeration units

The target of this study is to experimentally compare the performance of three different expansion devices for small-capacity subcritical R744 vapour-compression refrigeration units. The first considered expansion device was the conventional high-pressure expansion valve, which was selected as the baseline. The second assessed expansion device was a two-phase ejector for expansion work recovery whose refrigerant flow was modulated via the pulse-width modulation (PWM) strategy. Finally, the PWM approach was employed for controlling the refrigerant flow of the ejector motive nozzle while the refrigerant was not permitted to be drawn by the ejector suction nozzle. The results showed that the motive nozzle controlled via PWM effect offers similar effectiveness to a conventional high-pressure expansion valve in the subcritical regime. Furthermore, it was observed that the PWM ejector is able to control the high pressure effectively while increasing the coefficient of performance (COP) by up to 5.3 % without and by up to 7.9 % with overfed evaporator compared to the baseline in the transition regime. The results also showed that the installation of the conventional high-pressure expansion valve is not necessary. Finally, the yearly performance of the aforementioned expansion devices was assessed in five different locations, i.e., Athens (Greece), Phoenix (USA), New Delhi (India), Riyadh (Saudi Arabia) and Bangkok (Thailand). The outcomes revealed that the PWM ejector allows for a higher in yearly average COP (COPyearly avg) from 4.9 % (in Athens) to 11.8 % (in Bangkok) over the baseline.

Enhancing commercial check valves in downhole pump applications through laboratory testing system development

In this study, we aim to enhance the performance and longevity of downhole pumps employed in crude oil extraction in the oil industry. Downhole pumps play a pivotal role in the rod-pump system, comprising traveling and standing valves that function similarly to ball check valves. However, these valves often experience premature wear and tear. To address this concern, we embarked on experiments involving various check valve alternatives to conventional ball valves within downhole pumps. The testing conditions were controlled precisely. Furthermore, we evaluated four distinct check valve types, the original (representing the incumbent ball valves), spring-poppet (C), spring-ball (CB), and spring-poppet with soft-seated (S6C) check valves, within a controlled laboratory environment. We employed a TEXAPON N70 solution to replicate the properties and temperature conditions of crude oil. A portable ultrasonic flow meter was used to quantify the pump flow rate and assess its volumetric efficiency. In addition, we recorded data on the polished-rod load and plunger displacement to generate dynamometer cards, thereby enabling a comprehensive evaluation of the operational performance of the pump. Furthermore, we conducted a vacuum test to scrutinize valve leakage, which is a crucial indicator of the operational lifespan of a downhole pump. Our findings show that incorporating the CB check valve with the RHB pump in oil wells operated by the PTT Exploration and Production Public Company Limited (PTTEP) could result in a 15 % increase in volumetric efficiency and a remarkable 160 % improvement in durability compared to the original ball check valve.

Diagnostic Benefit of Molecular Imaging in Patients Undergoing Heart Valve Surgery for Infective Endocarditis.

(1) Background: The successful treatment of infective endocarditis (IE) relies on detecting causative pathogens to administer targeted antibiotic therapy. In addition to standard microbiological cultivation of pathogens from tissue obtained during heart valve surgery, the potential of molecular biological methods was evaluated. (2) Methods: A retrospective study was performed on heart valve tissue from 207 patients who underwent heart valve surgery for IE. FISHseq (fluorescence in situ hybridization combined with 16S rRNA gene PCR and sequencing) was performed in addition to conventional culture-based microbiological diagnostics. The diagnostic performance of FISHseq was compared with the conventional methods and evaluated in the clinical context. (3) Results: Overall, FISHseq provided a significantly higher rate of specific pathogen detection than conventional valve culture (68.1% vs. 33.3%, p < 0.001). By complementing the findings from blood culture and valve culture, FISHseq was able to provide a new microbiological diagnosis in 10% of cases, confirm the cultural findings in 24.2% of cases and provide greater diagnostic accuracy in 27.5% of cases. FISHseq could identify a pathogen in blood-culture-negative IE in 46.2% of cases, while valve culture provided only 13.5% positive results (p < 0.001). (4) Conclusions: This study demonstrates that using FISHseq as an additional molecular biological technique for diagnostics in IE adds substantial diagnostic value, with potential implications for the treatment of IE. It provides pathogen detection, especially in cases where conventional microbiological cultivation is negative or inconclusive.

Minimally invasive vs. conventional mitral valve surgery: a meta-analysis of randomised controlled trials.

The evidence underlying the efficacy and safety of minimally invasive mitral valve surgery (MIMVS) is inconclusive. We conducted a meta-analysis to evaluate whether MIMVS improves clinical outcomes compared with conventional sternotomy. We searched MEDLINE (via PubMed), Embase, the Cochrane Library, and ClinicalTrials.gov from inception to January 2024 for all randomised controlled trials (RCTs), comparing MIMVS with conventional mitral valve surgery. RevMan 5.4 was used to analyse the data with risk ratio (RR) and mean difference (MD) as the effect measures. Eight studies reporting data on 7 RCTs were included in our review. There was no significant difference in all-cause mortality, the number of patients requiring blood product transfusion, and the change from baseline in the SF-36 physical function scores between the MIMVS and conventional sternotomy groups. MIMVS reduced the length of hospital stay (MD -2.02 days, 95% CI: -3.66, -0.39) but did not affect the length of ICU stay, re-operation for bleeding, and the incidence of renal injury, wound infection, neurological events, and postoperative moderate or severe mitral regurgitation. MIMVS was associated with a trend toward lower postoperative pain scores (MD -1.06; 95% CI: -3.96 to 0.75). MIMVS reduced the number of days spent in the hospital and showed a trend toward lower postoperative pain scores, but it did not decrease the risk of all-cause mortality or the number of patients needing blood product transfusions. Further large-scale RCTs are required to inform definitive conclusions, particularly with regard to quality-of-life outcomes investigating functional recovery. PROSPERO (CRD42023482122).

Mechanical Characteristics and Miniaturization Design of the Electromagnetic Valve Used in Drilling Robots

The maximum radial size of the conventional three-bit four-way electromagnetic cartridge valve is greater than the largest containable size of the fluid control valve used for downhole robots. This paper proposes two kinds of solutions to reduce the radial dimension of the three-bit four-way electromagnetic insertion valve: one is to reduce the radial arrangement of the coil and increase the axial arrangement of the coil, and the other is to reduce the diameter of the moving iron core to reduce the winding radius of the coil. Using the theoretical model established in the following text, a simulation experiment was conducted. The results show that the movement of the valve spool is basically completed within 30 ms. Then, a matching experiment on the electromagnetic insertion valve was designed and conducted. The experimental results show that the opening time of the solenoid valve on the left coil is about 52 ms, and the opening time of the solenoid valve on the right coil is about 44 ms. The reaction time of the valve spool is suitable for the practical application of the solenoid valve. The significance of this paper is the reduced radial size of the three-bit four-way electromagnetic insertion valve. These improvements have reduced the size of downhole drilling robots, which facilitates the application of downhole drilling robots in narrower environments.

Experiments and three-dimensional flow simulations on twin-screw pumps operated as control valves for energy recovery

This study explores the characteristics of twin-screw pumps when operated in turbine, i.e., reverse mode as an alternative to traditional control valves in piping systems for recovering energy. Experimental and flow simulation methods are employed. By an overset grid technique, unsteady three-dimensional (3D) flow simulations are conducted, ensuring high cell quality and high spatial resolution, particularly in wall proximity and within the gaps. To assess viscosity effects, pump and turbine mode characteristics are analyzed for water and oil. Compared to water, a pronounced reduction of the flow rate dependence on pressure difference is revealed for highly viscous oil. The gap flow in oil is significantly affected by the spindles’ rotational speed and direction, whereas water displays minimal influence. Analyzing the variation in gap sizes, a 50% reduction in the minimum flank gap width leads to a slight rise in volumetric efficiency with negligible overall efficiency effects. Our findings underscore that utilizing twin-screw pumps as turbines for high-viscosity fluids can potentially recover up to 50% of the energy instead of dissipating it by using conventional control valves.

Chondroitin Sulfate Derivative Cross-Linking of Decellularized Heart Valve for the Improvement of Mechanical Properties, Hemocompatibility, and Endothelialization.

Tissue-engineered heart valve (TEHV) has emerged as a prospective alternative to conventional valve prostheses. The decellularized heart valve (DHV) represents a promising TEHV scaffold that preserves the natural three-dimensional structure and retains essential biological activity. However, the limited mechanical strength, fast degradation, poor hemocompatibility, and lack of endothelialization of DHV restrict its clinical use, which is necessary for ensuring its long-term durability. Herein, we used oxidized chondroitin sulfate (ChS), one of the main components of the extracellular matrix with various biological activities, to cross-link DHV to overcome the above problems. In addition, the ChS-adipic dihydrazide was used to react with residual aldehyde groups, thus preventing potential calcification. The results indicated notable enhancements in mechanical properties and resilience against elastase and collagenase degradation in vitro as well as the ability to withstand extended periods of storage without compromising the structural integrity of valve scaffolds. Additionally, the newly cross-linked valves exhibited favorable hemocompatibility in vitro and in vivo, thereby demonstrating exceptional biocompatibility. Furthermore, the scaffolds exhibited traits of gradual degradation and resistance to calcification through a rat subcutaneous implantation model. In the rat abdominal aorta implantation model, the scaffolds demonstrated favorable endothelialization, commendable patency, and a diminished pro-inflammatory response. As a result, the newly constructed DHV scaffold offers a compelling alternative to traditional valve prostheses, which potentially advances the field of TEHV.

Multi-Objective Optimization towards Heat Dissipation Performance of the New Tesla Valve Channels with Partitions in a Liquid-Cooled Plate

The utilization of liquid-cooled plates has been increasingly prevalent within the thermal management of batteries for new energy vehicles. Using Tesla valves as internal flow channels of liquid-cooled plates can improve heat dissipation characteristics. However, conventional Tesla valve flow channels frequently experience challenges such as inconsistencies in heat dissipations and unacceptably high levels of pressure loss. In light of this, this paper proposes a new type of Tesla valve with partitions, which is used as internal channel for liquid-cooled plate. Its purpose is to solve the shortcomings of existing flow channels. Under the working conditions of Reynolds number equal to 1000, the neural network prediction-NSGA-II multi-objective optimization method is used to optimize the channel structural parameters. The objective is to identify the optimal structural configuration that exhibits the greatest Nusselt number while simultaneously exhibiting the lowest Fanning friction factor. The variables to consider are the half of partition thickness H, partition length L, and the fillet radius R. The study result revealed that the optimal parameter combination consisted of H = 0.25 mm, R = 1.253 mm, L = 0.768 mm, which demonstrated the best performance. The Fanning friction factor of the optimized flow channel is substantially reduced compared to the reference channel, reducing by approximately 16.4%. However, the Nusselt number is not noticeably increased, increasing by only 0.9%. This indicates that the optimized structure can notably reduce the fluid’s friction resistance and pressure loss and slightly enhance the heat dissipation characteristics.

A comprehensive mathematical theory and optimized design of a high-frequency electro-pneumatic variable valve actuator for a camless IC engine

This paper discusses the development of a detailed mathematical theory and its use for the design of an electronically controlled, double-acting Variable Valve Actuation (VVA) mechanism for a camless internal combustion engine, that offers a comprehensive control over the timings and the motion of the valves such that any arbitrary time-variation of the valve lift profile can be obtained at variable rotational speeds of the engine shaft. The developed theory encompasses the thermo-fluid-dynamic as well as the applied-mechanical aspects of the actuator cylinder-engine valve system performance, the dynamics of the valve actuation being characterized by parameters such as valve opening duration, peak lift and seating velocity. The prediction of the mathematical theory compares well with several experimental data sets obtained from an in-house pneumatic VVA set-up. A new design methodology is formulated for determining the appropriate dimensions of the actuator, operating thermodynamic parameters and the electronic control of the various valve events for a desired range of engine rotational speed. Several parameters in the new design philosophy are kept within acceptable ranges established from time-tested data obtained from conventional cam-based valve actuation. For example, a new pneumatic cushioning strategy has been developed that is simple, effective and energy-efficient, and is able to keep the valve seating velocity within an acceptable range (0.08–1.13 m/s). The work also discusses the implementation of several constraints that are necessary for the design of a practically viable pneumatic actuator. The evolution of a design matrix map for the electro-pneumatic VVA is quantified for the engine rotational speed varying up to 5500 rpm.

A fluid-structure interaction simulation on the impact of transcatheter micro ventricular assist devices on aortic valves

Background and ObjectiveThe implantation of ventricular assist devices (VADs) has become an important treatment option for patients with heart failure. Aortic valve insufficiency is a common complication caused by VADs implantation. Currently, there is very little quantitative research on the effects of transcatheter micro VADs or the intervention pumps on the aortic valves. MethodsIn this study, the multi-component arbitrary Lagrange-Eulerian method is used to perform fluid-structure interaction simulations of the aortic valve model with and without intervention pumps. The effects of intervention pumps implantation on the opening area of the aortic valves, the stress distribution, and the flow characteristics are quantitatively analyzed. Statistical results are consistent with clinical guidelines and experiments. ResultsThe implantation of intervention pumps leads to the valve insufficiency and causes weak valve regurgitation. In the short-term treatment, the valve regurgitation is within a controllable range. The distribution and variation of stress on the leaflets are also affected by intervention pumps. The whirling flow in the flow direction affects the closing speed of the aortic valves and optimizes the stress distribution of the valves. In the models with whirling flow, the effects of intervention pumps implantation on valve motion and stress distribution differ from those without whirling flow. However, the valve insufficiency and valve regurgitation caused by intervention pumps still exist in the models with whirling flow. Conventional artificial bioprosthetic valves have limited effectiveness in treating the valve diseases caused by intervention pumps implantation. ConclusionsThis study quantitatively investigates the impact of intervention pumps on the aortic valves, and investigates the effect of blood rotation on the valve behavior, which is a gap in previous research. We suggest that in the short-term treatment, the implantation of intervention pumps has limited impact on aortic valves, caution should be exercised against valve regurgitation issues caused by intervention pumps.

Rapid-Deployment Valves versus Conventional Valves in Aortic Valve Replacement in Intermediate-Risk Patients

Background: Aortic valve replacement (AVR) in intermediate-risk (IR) patients is particularly challenging when determining the type of prosthesis to use. Rapid-deployment valves (RD-V) are emerging as a potential alternative in this patient population. Objectives: To compare early mortality, postoperative complications, and transvalvular hemodynamic parameters between AVR with conventional valves and RD-V in IR patients. Methods: We conducted a retrospective observational study of consecutive IR patients (STS-Prom score 4-8) undergoing AVR with conventional prostheses and RD-V between 2007 and 2023. Results: A total of 205 patients were included (140 AVR vs. 65 RD-V). Surgical risk was similar between both groups (STS-Prom 5.07 % vs. 5.7 % respectively, p = 0.211). The minimally invasive approach was more common in the RD-V group (32.3% vs. 0.7%, p &lt; 0.001). The cardiopulmonary bypass time and aortic cross-clamp time was significantly shorter in the RD-V group (134.5 vs. 100 min and 104 vs. 73 min, respectively, p &lt; 0.001). There was a trend to lower incidence of pacemaker implantation in the conventional valve group (4.3% vs. 10.8%, p = 0.075). There were no significant differences in postoperative complications, and a strong trend to lower 30-dat mortality with RD-V (0% vs. 5.7% for conventional valves, p = 0.057). The mean postoperative gradient across the prosthesis was significantly lower in the RD-V group (7.90 ± 3.3 mm Hg vs. 12.74 ± 6.07 mm Hg, p &lt; 0.001). There were no differences in the incidence of valve thrombosis or prosthetic endocarditis. Conclusions: Rapid deployment valves demonstrated trend to lower mortality, shorter cardiopulmonary bypass time and aortic cross-clamp time, improved hemodynamic profile, and were easier to implant via a minimally invasive approach.

A novel design model of flow channel paths for additive manufacturing

PurposeThis paper aims to propose a method for automatic design of additive manufacturing (AM) flow channel paths driven by path length and pressure loss. The research focuses on the automatic design of channel paths, intending to achieve the shortest flow channel length or minimum pressure loss and improve the design efficiency of AM parts.Design/methodology/approachThe initial layout of the flow channels is redesigned to consider the channels print supports. Boundary conditions and constraints are defined according to the redesigned channels layout, and the equation consisting of channel length and pressure loss is used as the objective function. Then the path planning simulation is performed based on particle swarm algorithm. The proposed method describes the path of flow channels using spline cures. The spline curve is controlled by particle (one particle represents a path), and the particle is randomly generated within the design space. After the path planning simulation is completed, the generated paths are used to create 3D parts.FindingsCase study 1 demonstrates the automatic design of hydraulic spool valve. Compared to conventional spool valve, the pressure loss was reduced by 86% and the mass was reduced by 83%. The design results of case study 2 indicate that this approach is able to find the shortest channel path with lower computational cost.Originality/valueThe automatic design method of flow channel paths driven by path length and pressure loss presented in this paper provides a novel solution for the creation of AM flow components.