Permanent pacemaker implantation after On-X surgical aortic valve replacement: SWEDEHEART observational study

ObjectiveBioprosthetic aortic valves with an extended subannular component, such as transcatheter valves, exert increased compression on the cardiac conduction system and increase the risk for permanent pacemaker implantation. It is unknown if the On-X mechanical prosthetic valve, which has an elongated subannular valve housing, increases the risk of permanent pacemaker implantation following aortic valve replacement.DesignObservational nationwide cohort study.SettingSwedish population-based study.ParticipantsAll patients aged 18–65 years who underwent primary mechanical aortic valve replacement in Sweden between 2005 and 2018. We used the Swedish Web system for Enhancement and Development of Evidence-based care in Heart disease Evaluated According to Recommended Therapies register and other Swedish national health-data registers.ExposurePatients implanted with an On-X valve versus patients implanted with other bileaflet mechanical valves.Primary and secondary outcome measuresPrimary outcome measure was permanent pacemaker implantation within 30 days of surgery.ResultsA total of 2602 patients were included, and 581 patients received an On-X valve and 2021 patients received a St Jude Masters/Regent (n=945) or Carbomedics Reduced valve (n=1076). In the total study population, 115 (4.4%) permanent pacemaker implantations were performed within 30 days after aortic valve replacement. In the propensity score matched population, there was no significant difference in the rate of permanent pacemaker implantation in the On-X group compared with the control group: 3.6% (95% CI: 2.4% to 5.5%) vs 4.0% (95% CI: 2.7% to 5.9%), p=0.877.ConclusionsThe On-X prosthetic heart valve was associated with a similarly low risk for permanent pacemaker implantation after aortic valve replacement compared with other conventional bileaflet mechanical valves. The On-X elongated subannular valve housing does not interfere with the cardiac conduction system.

Development of metallic 3d-printed water hydraulic proportional directional control valve

New additive metal powder technologies are increasingly used for various prototypes. Different powder materials can be used for very complex shapes. Water hydraulics needs new technologies and new approaches to enable more frequent use by users. A new shape of housing for a water hydraulic proportional directional control valve was designed. FEM and CFD analyses of the valve housing were performed. Based on the results of the initial numerical analyses, topological optimization of the valve housing was performed. The prototype of the valve was fabricated from non-corrosive Inconel powder using 3D printing process. After machining, the valve was assembled and experimentally validated on the water hydraulic test rig. The new 3D-printed Inconel valve housing is more than 3 times lighter than similar housings of industrial valves.

Computer-aided engineering (CAE) simulation for the robust gating system design: Improved process for investment casting defects of 316L stainless steel valve housing

Defects in investment casting will inevitably reduce the lifetime and degrade the casting quality and increase manufacturing costs, accordingly. In particular, shrinkage porosity was numerically conducted, and a retained melt modulus model was implemented to analyze highly probable regions. The proposed casting schemes of gating designs are compared by quality of casting (shrinkage porosity) and practical feasibility in terms of small hole drilling machinability. The purpose of this study was to determine the feasible plan with the lowest PES (percentage of elements with shrinkage porosity) while promoting the near net shape casting with minimum machining cost and increase material usage. Virtual thermo-dynamical sensors were adopted in the simulations to indicate the impacts of different gating system of pattern assembly on the cooling gradient and direction of solidification. The best-case scenario of investment casting conditions was chosen to fabricate valve housing in an investment casting foundry. Experimental results of X-ray image differentiated nearly none of the pernicious defects that typically occurred with proposed casting, authenticating the proposed scheme's efficacy accordingly.

Sustainable development of pressure equipment using 3D Digital Image Correlation method

As pressure equipment is most commonly used in various industrial fields, making manufacturing processes eco-friendlier (e.g., mass reduction of the final product, material and energy savings, etc.) and transitioning to sustainable production by developing eco-innovative products will have a positive effect on the environment. The aim of this paper is to analyze globe valve housing exposed to internal pressure using full-field experimental 3D digital image correlation (3D-DIC) method and numerical strain and stress data in order to propose improvements for more sustainable development, with respect to practical engineering application of EN standards. The highest von Mises strain values around 0.03% were measured on the point of highest geometrical discontinuity, sphere/cylinder intersection. Stresses of the examined globe valve using numerical and theoretical approach are significantly below material yield limit and allowable stress for internal pressure values of 30 bar, that is significantly higher than nominal operating pressure of 6 bar, proving that structure is over-dimensioned and can be optimized. New experimental procedure development and application in full-field strain analysis contributes to increased valve housing reliability, mass reduction and material and energy savings during manufacturing which directly affects its eco-friendliness, lowers manufacturing price and increases market competitiveness.

Influence of Coolant Pressure Size on Surface Roughness when Stainless Steel Machining

The paper is focused on the influence of the coolant pressure on the surface roughness of the workpiece when machining stainless steels. The components were machined on a STAR SR-32J dual spindle machining center and an external cooling unit HYTEK CHAV 160/150-AF-F-OL was used for cooling. Two stainless steel components were investigated, namely the gas control valve rod and the high-pressure control valve housing, which require low roughness Ra after machining (less than 0.375 and 0.25 micrometers respectively). The first component was tested at 8 different pressures in the range of 150 bar - 10 bar and the second component at 4 different pressures in the range of 120 bar - 10 bar. The roughness parameters were measured by the contact method using the MITUTOYO Surftest SJ-410 Roughness Tester and the Alicona InfiniteFocus optical microscope. Based on these sample input parameters, it was evaluated howmuch the pressure affects the surface quality or suggested its reduction due to the high cost of operation of the external high-pressure equipment.