Changes In Wave Velocity Research Articles

Metabolic Alterations Differentiating Cardiovascular Maladaptation from Athletic Training in American-Style Football Athletes.

Metabolomics identifies molecular products produced in response to numerous stimuli, including both adaptive (includes exercise training) and disease processes. We analyzed a longitudinal cohort of American-style football (ASF) athletes, who reliably acquire maladaptive cardiovascular (CV) phenotypes during competitive training, with high-resolution metabolomics to determine whether metabolomics can discriminate exercise-induced CV adaptations from early CV pathology. Matched discovery ( n = 42) and validation ( n = 40) multicenter cohorts of collegiate freshman ASF athletes were studied with longitudinal echocardiography, applanation tonometry, and high-resolution metabolomics. Liquid chromatography-mass spectrometry identified metabolites that changed ( P < 0.05, false discovery rate <0.2) over the season. Metabolites demonstrating similar changes in both cohorts were further analyzed in linear and mixed-effects models to identify those associated with left ventricular mass, tissue-Doppler myocardial E ' velocity (diastolic function), and arterial function (pulse wave velocity). In both cohorts, 20 common metabolites changed similarly across the season. Metabolites reflective of favorable CV health included an increase in arginine and decreases in hypoxanthine and saturated fatty acids (heptadecanoate, arachidic acid, stearate, and hydroxydecanoate). In contrast, metabolic perturbations of increased lysine and pipecolate, reflective of adverse CV health, were also observed. Adjusting for player position, race, height, and changes in systolic blood pressure, weight, and pulse wave velocity, increased lysine ( β = 0.018, P = 0.02) and pipecolate ( β = 0.018, P = 0.02) were associated with increased left ventricular mass index. In addition, increased lysine ( β = -0.049, P = 0.01) and pipecolate ( β = -0.052, P = 0.008) were also associated with lower E ' (reduced diastolic function). ASF athletes seem to develop metabolomic changes reflective of both favorable CV health and early CV maladaptive phenotypes. Whether metabolomics can discriminate early pathologic CV transformations among athletes is a warranted future research direction.

Effect of Crack Angle and Length on Mechanical and Ultrasonic Properties for the Single Cracked Sandstone Under Triaxial Stress Loading-Unloading

The disturbance due to coal mining causes the surrounding rock to undergo a complex process of stress changes during which the axial pressure and the confining pressure usually change accordingly at the same time. Existing studies generally investigated this process from a static perspective, which was not rigorous. The mechanical characterization of rock is very important to understand the failure of rock mass and the safety of mining during mining disturbance. Based on theoretical analysis, we conducted axial loading and radial unloading tests on the cracked sandstone, which was combined with the ultrasonic testing technology to examine its failure rules and to characterize and analyze its failure process using longitudinal wave velocity. The results demonstrated that crack length and angle had a significant impact on the strength and mechanical properties of sandstone, and the former had a greater impact on the strength of sandstone than the latter. As the crack length increased, the strength, elastic modulus, and deformation modulus of sandstone decreased, and the strength of sandstone increased as the crack angle increased. Elastic and deformation moduli first decreased and then increased. Furthermore, Poisson’s ratio increased slowly, then decreased slowly, and finally increased rapidly as the lateral pressure coefficient diminished, and Poisson’s ratio was more sensitive to changes in the angle. In this study, the change of longitudinal wave velocity reflected the whole process of sandstone failure. When the wave velocity was stable, the rock was at the yield limit point. Moreover, when the wave velocity was unstable, the sandstone was in a progressive failure period, and as a result, the wave velocity decreased and the sandstone cracked.

Experimental investigations of static mechanical properties and failure characteristics of damaged diorite after dynamic triaxial compression

To investigate the static mechanical properties and failure characteristics of damaged rocks after impact under realistic in-situ stress, dynamic triaxial compression tests with different strain rates and confining pressures were conducted on diorite by a modified split Hopkinson pressure bar . The damage factor was calculated according to the change of the longitudinal wave velocity of rocks before and after the impact, and the residual strengths of the damaged diorite were obtained by uniaxial compression and Brazilian tensile tests . In addition, three brittleness indexes based on the residual strength were adopted to evaluate the brittleness of damaged specimens, and fractal dimension was introduced to study the fragmentation characteristics. The results show that the dynamic peak stress, strain, elastic modulus , damage factor and plastic deformation of diorite all increase with increasing strain rate, i.e., rate dependence, and the increasing rate decreases with increasing confining pressure. The increment in confining pressure leads to the increase of dynamic peak stress, elastic modulus, static residual strength and brittleness, and the increasing rate increases with increasing strain rate, while other physio-mechanical parameters decrease with confining pressure. The post-peak behavior of dynamic stress-strain curves is divided into two classes according to the strain rate and fracture state of rocks under dynamic loading. Upon the strain rate increases above 87 s −1 , the brittleness of damaged specimens generally decreases to moderately brittle or even low brittle, and the corresponding drillability becomes much easier. The fractal dimension of damaged specimens increases with the increase of confining pressure and decreases linearly with the increase of strain rate .

Aortic stiffness and systemic inflammation changes predict clinical response to intravitreal anti-vascular endothelial growth factor therapy in patients with age-related macular degeneration.

Aortic stiffness and systemic inflammation are predictors of cardiovascular risk. Anti-vascular endothelial growth factor agents (anti-VEGF), injected intravitreally, can reverse the course of exudate age-related macular degeneration (AMD). We sought to investigate the association of changes in aortic stiffness and systemic inflammation with response to anti-VEGF therapy. 54 patients (mean age: 76 ± 10 years) with AMD received two consecutive monthly intravitreal injections of ranibizumab (0.5 mg). The primary outcome measure was change in carotid-femoral pulse wave velocity (PWV) from baseline to 1 month after the second injection. Secondary endpoint was the change in serum high sensitivity interleukin-6 (hsIL-6) levels. Ranibizumab caused a decrease of PWV after the first (by 0.36 ± 1.4 m/s) and the second injection (by 0.31 ± 1.4 m/s) and remained decreased 1 month after the second injection (overall P < 0.05). PWV decreased significantly in good responders (according to clinical criteria and fundus findings, P = 0.004), whereas it increased numerically in poor responders (P = 0.21) over the study period. In responders, hsIL-6 decreased after the first injection and remained decreased 1 month after the second injection (by 0.63 ± 0.35 pg/ml, overall P = 0.02). PWV (P = 0.005) and hsIL-6 (P = 0.042) were independent predictors of improvement after adjusting for age and presence of hypertension and diabetes. The decrease in PWV through the whole study period was positively correlated with the reduction in hsIL-6 (r = 0.36, P < 0.01). Intravitreal ranibizumab injections lead to a decrease in PWV and hsIL-6. Both parameters predict clinical improvement and may aid to improving treatment targeting and hence therapeutic outcome in patients with AMD.

Ultrasonic Coda Wave Experiment and Simulation of Concrete Damage Process under Uniaxial Compression

Using the coda wave interferometry (CWI) method to obtain the ultrasonic coda wave characteristics of loaded concrete is an important method to evaluate the mechanical response of concrete. In this paper, the ultrasonic coda wave characteristics of C40–C70 concrete specimens (four strengths of concrete) under uniaxial compression were tested by laboratory experiments. Furthermore, to clarify the relationship between the internal damage process of concrete and the change rate of coda wave velocity, an ultrasonic coda wave discrete element simulation model combined with digital image processing technology was established. The results show that the coda wave is very sensitive to small changes in the compressive damage to concrete, and the change in coda wave velocity can correspond to the development process of concrete damage. This research is conducive to a better understanding of the complex material behavior of compressive concrete and proves the feasibility of ultrasonic field simulation and processing by using numerical simulation images of concrete damage.

Dynamic Properties of Calcareous Sands from Urban Areas of Abu Dhabi

Abu Dhabi (ABD) has recently developed its national building code that mandates dynamic analysis of large structures to seismic loadings. Large strain dynamic properties such as shear modulus (G) and damping ratio (D) of local undisturbed calcareous sands are not available. Designers are compelled to choose degradation models from studies on calcareous sands of other regions that are usually reconstituted. This research presents for the first time large strain dynamic properties of calcareous sands of urban ABD. Undisturbed samples are collected from different areas of urban ABD and are tested in cyclic triaxial (CT) devices fitted with bender elements (BE). The dynamic properties as functions of confinement are curve fitted with power models, whereas their variation with shear strain level is curve fitted with hyperbolic models. The results are compared with findings of previous studies on calcareous and silica sands. The results indicate that dynamic properties of all samples degrade with shear strain at almost the same rate irrespective of their spatial distribution. The proposed degradation models can therefore be used in dynamic analyses. The results from this study show smaller rates of degradation in dynamic properties compared to other studies on similar sands. The change in low-strain shear wave velocity (Vs) with confinement is significant among the tested samples; therefore, a site-specific evaluation of Vs is recommended. The dynamic properties of calcareous sands of ABD and previous studies however exhibit larger degradation with shear strain and a smaller increase in confinement compared to silica sands.

A novel fault location method for hybrid lines based on traveling wave

In this paper, a novel fault traveling wave-based location method for hybrid lines is proposed. According to the refraction characteristics of fault traveling wave (TW) at junction nodes, the node ratio coefficient value Q is defined based on the amplitude of traveling wave. Then, by comparing the Q values of junction nodes and fault points, a fault section identification principle is proposed to determine the fault line section for hybrid lines. After identification of fault line section, a double-ended fault location method is revised via adding the location compensation factors to mitigate the effect of traveling wave velocity changes on fault location for multi-section hybrid lines. Additionally, considering the detection problems of arrival time for TW signals, the extreme-point symmetric mode decomposition (ESMD) method and Teager energy operator (TEO) are proposed. The ESMD method is applied to decompose the sampled fault traveling wave signals into several intrinsic modes to filter out the fundamental frequency and low frequency signals. The TEO is employed to track the characteristics of TW signals. Effectiveness of the proposed method is validated in PSCAD. Results show that the ESMD-TEO can detect TW signals effectively, and the proposed fault location method can determine the fault line section and locate fault positions correctly.

Effects of Particle Shape on the Shear Wave Velocity and Shear Modulus of 3D Printed Sand Analogs

Isolating the effects of individual particle properties (e.g. shape, size, mineralogy, surface roughness) on the mechanical behavior of naturally occurring coarse-grained soils is a significant challenge in experimental studies. This challenge can be addressed by recent advances in 3D printing technology which enable generation of artificial sand-sized particles with independent control over particle size and shape. In this study, bender element tests are conducted to examine the isolated effects of particle shape on the shear wave velocity and shear modulus of 3D printed sand analogs. The experimental results show that the shear wave velocity and shear modulus of the 3D printed sand specimens exhibit a relationship with mean effective stress that is in agreement to that reported for natural sands. The specimens composed of 3D printed sands with greater particle roundness and sphericity exhibit greater shear wave velocity and shear modulus for a given void ratio, relative density, and mean effective stress. The changes in shear wave velocity can be captured in terms of differences in individual particle shape parameters such as roundness and sphericity as well as combined particle shape parameters such as regularity. Regression analysis is used to develop relationships between shear wave velocity and particle shape parameters and void ratio, which are shown to be in agreement with previously-published relationships and to reliably predict the shear wave velocity of natural sands. The results presented herein highlight the usefulness of testing 3D printed soils to identify functional trends and dependencies between soil response parameters and intrinsic properties. However, this requires verification of the results against published trends and assessment of the possible effects of the differences in constituent material between the 3D printed and the natural soils.

Effects of Fracture Connectivity on Rayleigh Wave Dispersion

AbstractPassive seismic characterization is an environmentally friendly method to estimate the seismic properties of the subsurface. Among its applications, we find the monitoring of geothermal reservoirs. One key characteristic to ensure a productive management of these reservoirs is the degree of fracture connectivity and its evolution, as it affects the flow of fluids within the formation. In this work, we explore the effects of fracture connectivity on Rayleigh wave velocity dispersion accounting for wave‐induced fluid pressure diffusion (FPD) effects. To this end, we consider a stratified reservoir model with a fractured water‐bearing formation. For the stochastic fracture network prevailing in this formation, we consider varying levels of fracture density and connectivity. A numerical upscaling procedure that accounts for FPD effects is employed to determine the corresponding body wave velocities. We use a Monte‐Carlo‐type approach to obtain these velocities and incorporate them in the considered fractured reservoir model to assess the sensitivity of Rayleigh wave velocity dispersion to fracture connectivity. Our results show that Rayleigh wave phase and group velocities exhibit a significant sensitivity to the degree of fracture connectivity, which is mainly due to a reduction of the stiffening effect of the fluid residing in connected fractures in response to wave‐induced FPD. These effects cannot be accounted for by classical elastic approaches. This suggests that Rayleigh wave velocity changes, which are commonly associated with changes in fracture density, may also be related to changes in interconnectivity of pre‐existing or newly generated fractures.

Seismic Velocity Variations at Different Depths Reveal the Dynamic Evolution Associated With the 2018 Kilauea Eruption

AbstractAdvances in noise‐based velocity change measurements have revealed anomalies before volcanic eruptions. Still, it is difficult to assign them to a certain depth based on the traditional coda wave method. Here we used volcanic tremor (1–2.5 s) and oceanic noise (3 and 3.5 s) as passive sources to calculate the Rayleigh wave velocity changes associated with the 2018 Kilauea eruption. Our simulation show that the velocity decreased at least by 5% at 1–2 km depth beneath the East Rift zone in the co‐eruption time. Before the eruption, we observed a decrease (1%) at the same depth, whereas, at the depths of 0–1 and 2–8 km, the velocity increased by 0.2%–1%. Combined with microearthquakes, The Global Positioning System data, and numerical simulation, our observations suggest that magma intrusion may open the magma dike at 1–2 km depth but induce higher compressive stress (about 3.6–14.4 MPa) in the surrounding areas.

Earthquake‐Derived Seismic Velocity Changes During the 2018 Caldera Collapse of Kīlauea Volcano

AbstractThe 2018 Kīlauea caldera collapse produced extraordinary sequences of seismicity and deformation, with 62 episodic collapse events which significantly altered the landscape of the summit region. Despite decades of focused scientific studies at Kīlauea, detailed information about the internal structure of the volcano is limited. Recently developed techniques in seismic interferometry can be used to monitor the internal structure of an active volcano more directly by detecting subtle spatiotemporal changes in seismic wave velocity, but their utility relies on accurate interpretations of the underlying phenomena causing those velocity changes. Here, we retrospectively apply repeating‐earthquake‐based seismic interferometry to the 2018 Kīlauea eruption sequence. We find that seismic velocities changed over two distinct time scales: a sudden increase followed by a slower decrease in velocity in the hours following each collapse event, and a gradual, long‐term decrease in velocity over several weeks that ceased approximately 1 month prior to the end of the eruption. Modeling suggests that short‐term changes can be explained by magma reservoir pressurization which specifically closed vertical ring fractures. Long‐term changes are related to subsidence of the caldera and likely include the influence of inelastic strain from the formation of new fractures. These observations provide new insights into the evolution of Kīlauea during its progressive collapse and will inform future interpretations for near‐real‐time monitoring at hazardous volcanoes around the world using similar techniques, especially where a dominant fracture orientation is present.

Elastic Wave Velocity Changes Due to the Fracture Aperture and Density, and Direct Correlation With Permeability: An Energetic Approach to Mated Rock Fractures

AbstractIn an effort to reveal the subsurface hydraulic changes in fractures by seismic monitoring, aperture‐related velocity changes need to be investigated. We developed a numerical approach for calculating changes in elastic wave velocity with fracture aperture opening by determining the internal energy of a digitized fracture model based on natural rough surfaces. The simulated local elastic energy revealed that the interaction energy converged within 1.5 mm of the mean fracture position, and was insignificant unless the fractures intersected. This energetic approach clarified the aperture‐velocity relationship and reproduced the experimental results. Further calculations using digital fractures with various sizes and densities demonstrated that the velocity can be accounted for by the superposition of a linear function of fracture density and quadratic function of aperture, and is insensitive to the fracture size. Although the relationship between fracture permeability and elastic wave velocity (i.e., the k‐V relationship) depends on the fracture density, the offset‐normalized k‐V relationship shows clear linearity with the fracture density. The proposed k‐V relationship as a function of the aperture and fracture density indicates that laboratory‐scale fracture properties of a single fracture can be applied to multiple fractures on a larger scale. Our findings can be used to interpret temporal changes in seismic observations and to monitor fluid flow in fractures.

FEM Simulation of a High-Performance 128°Y-X LiNbO3/SiO2/Si Functional Substrate for Surface Acoustic Wave Gyroscopes.

To obtain a high-performance surface acoustic wave (SAW) gyroscope substrate, the propagation characteristics and gyroscopic effect of Rayleigh waves in a 128°Y–X LiNbO3/SiO2/Si (LNOI) functional substrate were investigated with a three-dimensional finite element method. The influence of LNOI structural parameters on Rayleigh wave characteristics, including the phase velocity (vp), electromechanical coupling coefficient (K2) and temperature coefficient of frequency (TCF), were analyzed. The results demonstrate that the SiO2 layer compensates for the negative TCF of 128°Y–X LiNbO3 and enhances the K2 of the LNOI substrate. The Rayleigh wave velocity change of the LNOI substrate after rotations in different directions was studied. The gyroscope gain factor (η) represents the strength of the gyroscopic effect in the differential traveling wave SAW gyroscope and is defined. The ηy and ηz of the LNOI substrate with different structural parameters were investigated. Finally, an LNOI substrate with an hLN/λ of 0.2 and an hSiO2/λ of 0.05 was obtained by balancing the characteristic parameters, with a K2 of 3.96%, TCF of −18.75 ppm/°C and ηy of 0.26. The LNOI substrate has a better gyroscopic effect and temperature stability than the 128°Y–X LiNbO3 crystal. The LNOI substrate meets device miniaturization and integration needs.

Analysis of Platen Superheater Tube Degradation in Thermal Power Plants via Destructive/Non-Destructive Characteristic Evaluation

Coal-fired power plants operating under Korea’s standard supercritical pressure operate in a high-temperature environment, with steam temperatures reaching 540 °C. A standard coal-fired power plant has a 30-year design life, and lifespan diagnosis is performed on facilities that have operated for more than 100,000 h or 20 years. Visual inspection, thickness measurements, and hardness measurements in the field are used to assess the degree of material degradation at the time of diagnosis. In this study, aging degradation was assessed using an electromagnetic acoustic transducer to measure the change in transverse ultrasonic propagation speed, and the results were compared to microstructural analysis and tensile test results. Based on the experimental results, it was found that the boiler tube exposed to a high-temperature environment during long-term boiler operation was degraded and damaged, the ultrasonic wave velocity was reduced, and the microstructural grains were coarsened. It was also confirmed through tensile testing that the tensile and yield strengths increased with degradation. Our findings prove that the degree of change in mechanical properties as a function of the material’s degradation state is proportional to the change in ultrasonic wave velocity.

Sound speed and refractive index of amorphous CaSiO3 upon pressure cycling to 40 GPa

Abstract Brillouin spectroscopy at room temperature and pressures up to 40 GPa documents nearly identical elasticity and refractive index of amorphous CaSiO3 created by two different methods: temperature-quenching the melt at ambient pressure and pressure-amorphizing crystalline wollastonite at room temperature. We find reproducible hysteresis of 0 to 8% on pressure cycling that is small relative to the 30 to 60% changes in shear and longitudinal wave velocities over this pressure range. Together with observed changes in refractive index and previous results from Raman spectroscopy, these measurements reveal a continuous and reversible change in atomic packing induced by pressure. Unlike many other silicate glasses, amorphous CaSiO3 exhibits highly reproducible properties, behaving smoothly and reversibly under pressure cycling and possessing similar structure and elasticity regardless of synthesis paths for the starting material, which suggests that the amorphous solid may mimic the liquid over the pressure range investigated.

Effect of snowfall on changes in relative seismic velocity measured by ambient noise correlation

Abstract. In mountainous, cold temperate and polar sites, the presence of snow cover can affect relative seismic velocity changes (dV/V) derived from ambient noise correlation, but this relation is relatively poorly documented and ambiguous. In this study, we analyzed raw seismic recordings from a snowy flat field site located above Davos (Switzerland), during one entire winter season (from December 2018 to June 2019). We identified three snowfall events with a substantial response of dV/V measurements (drops of several percent between 15 and 25 Hz), suggesting a detectable change in elastic properties of the medium due to the additional fresh snow. To better interpret the measurements, we used a physical model to compute frequency-dependent changes in the Rayleigh wave velocity computed before and after the events. Elastic parameters of the ground subsurface were obtained from a seismic refraction survey, whereas snow cover properties were obtained from the snow cover model SNOWPACK. The decrease in dV/V due to a snowfall was well reproduced, with the same order of magnitude as observed values, confirming the importance of the effect of fresh and dry snow on seismic measurements. We also observed a decrease in dV/V with snowmelt periods, but we were not able to reproduce those changes with our model. Overall, our results highlight the effect of the snow cover on seismic measurements, but more work is needed to accurately model this response, in particular for the presence of liquid water in the snowpack.

Comparison of high intensity interval training with standard cardiac rehabilitation on vascular function.

To compare the short- and long-term effects of high-intensity interval training (HIIT) with usual care moderate intensity continuous training (MICT) on systemic vascular function and stiffness in patients with coronary artery disease undergoing a cardiac rehabilitation program. Randomized controlled trial. Fifty-four patients (age=63±8years, 93% male) were randomized to complete 3sessions/week (2supervised, 1home-based) of either (1) 4×4-min HIIT or (2) 40-min MICT, for 4weeks. Patients then continued 3 unsupervised home-based sessions/week of their allocated training for 11months. Brachial artery flow-mediated dilation, pulse wave velocity, and blood pressure were measured at baseline, 4weeks, 3months, 6months, and 12months. Data were analyzed using linear mixed modeling and are presented as mean change from baseline (95% CI). HIIT showed a greater improvement in flow-mediated dilation compared to MICT after 4weeks [1.5% (0.9, 2.1) vs 0.1% (-0.5, 0.8); p=0.004) but not 12months [1.2% (-0.2, 2.5) vs 0.4% (-0.8, 1.7); p=0.153). There were no short- or long-term group differences for changes in pulse wave velocity, peripheral or central blood pressure between HIIT and MICT after 4weeks, or over 12months. A 4-week HIIT program was superior to MICT for improving vascular function, but not arterial stiffness or blood pressure. Over 12months, changes in vascular function, blood pressure, and arterial stiffness were similar for HIIT and MICT.

The effects of sorbing and non-sorbing gases on ultrasonic wave propagation in fractured coal

The acoustic wave propagation in geomaterials at different frequencies (ultrasonic, sonic, and seismic) has been extensively studied in the past to relate geomaterials' physical parameters to wave features. The ultrasonic analysis, commonly used for laboratory scale measurements, has been mainly employed to investigate wave propagation in non-sorbing rocks. The ultrasonic response of gas sorptive sediments particularly coal and its involved physical processes have however attracted limited attention to date. In this study, we use a combination of ultrasonic transmission and X-ray micro-computed tomography (XRCT) along with numerical simulation to investigate the mechanisms influencing the wave propagation in fractured coals. The simultaneous ultrasonic transmission and XRCT imaging are performed on stressed coal specimens saturated with non-sorbing (He) and sorbing (CO2) gases at different pore pressures. We further simulate ultrasonic wave propagation on segmented XRCT images and compare the numerical results with those of the experiments. A further numerical simulation is conducted on synthetic coal geometries to investigate the cleat and matrix property variation on wave propagation. Analysis of experimental and numerical results reveals that the closure of fractures (cleats) by matrix swelling (induced by CO2 adsorption) predominantly controls the change in wave velocities and the effect of change in matrix properties by gas adsorption on wave propagation is rather trivial. The numerical analysis on synthetic coal geometries further confirms that the effect of changes in coal matrix properties (density and stiffness) by gas adsorption on wave velocity is insignificant. In addition, the results show that the fracture aperture and density influence the wave velocities more significantly at low fracture porosity indicating that wave velocities are more sensitive to fractures when swelling is present (reduction in fracture porosity). These observations have significant implications in the characterization and monitoring of coal seam gas production and gas drainage.

The effect of aortic arch replacement on pulse wave velocity after surgery.

OBJECTIVESThe purpose of this study was to investigate the changes in pulse wave velocity (PWV) after aortic arch repair and to evaluate possible perioperative factors associated with an increase in PWV.METHODSEighty-nine patients with preoperative and postoperative PWV measurements who underwent surgical treatment for true aortic arch aneurysm were included in the study. The patients were treated by prosthetic graft replacement with or without the frozen elephant trunk technique or by hybrid surgery with a stent graft. Changes in PWV and perioperative factors were evaluated.RESULTSFifty-one patients were treated by prosthetic graft replacement; 22 patients were treated with the frozen elephant trunk procedure; and 16 patients were treated by hybrid surgery. A significant increase in PWV was observed in patients undergoing surgical treatment for aortic arch aneurysm regardless of the types of operations performed (all treatments: before, 1797 ± 397.8 cm/s vs after, 2061 ± 600.4 cm/s, P < 0.001; graft replacement: before, 1769 ± 398.1 cm/s vs after, 1895 ± 459.0 cm/s, P = 0.004; frozen elephant trunk procedure: before, 1911 ± 461.9 cm/s vs after 2307 ± 826.9 cm/s, P = 0.005; hybrid surgery: before, 1732 ± 273.3 cm/s vs after, 2254 ± 484.6 cm/s, P < 0.001). Differences in PWV were largest in patients treated with hybrid surgery and lowest in those treated with graft replacement (P = 0.002). In univariate analysis, an increase in PWV was positively correlated with treatment length (r = 0.41; P < 0.001); the use of a postoperative beta blocker was associated with a smaller increase in postoperative PWV (with: 165.0 ± 371.92 cm/s vs without: 439.4 ± 530.38 cm/s, P = 0.005). Multivariate analysis suggested that treatment length (coefficient 3.31, 95% confidence interval 0.056–6.562, P = 0.046) and postoperative beta blocker (coefficient −220.08, 95% confidence interval −401.972 to −38.183, P = 0.018) were factors independently associated with changes in PWV.CONCLUSIONSThere was a significant increase in PWV after aortic arch repair. Treatment length and use of postoperative beta blockers were factors associated with changes in postoperative PWV. Minimizing the treatment length and using postoperative beta blockers may attenuate the effects of prostheses on postoperative PWV.

Вплив фіксованої комбінації метформіну SR та глімепіриду на показники вуглеводного, ліпідного обміну та жорсткість артеріальної стінки у хворих на цукровий діабет 2-го типу

З метою вивчення впливу цукрознижувальної терапії за допомогою комбінації глімепіриду й метформіну SR упродовж 12 тижнів на показники вуглеводного й ліпідного обміну, динаміку рівня адипокінів у плазмі крові та показники жорсткості артеріальної стінки великих артерій (аорти та її гілок) спостерігали 30 пацієнтів (з них 18 — жінки) з цукровим діабетом 2-го типу віком 60,10 ± 1,08 року із серед-ньою тривалістю основного захворювання 5,7 ± 0,9 року. Результати. Порівняно з початковими значеннями відзначено покращення показників вуглеводного обміну. Так, рівень HbA1c знизився на 1,7 % (р &lt; 0,001), глікемії натще — на 22 % (р &lt; 0,001), постпрандіальної глікемії — на 44 % (р &lt; 0,001). Крім того, на тлі терапії спостерігалося покращення ліпідного обміну: зниження загального холестерину на 13,2 % (р &lt; 0,01), холестерину ліпопротеїнів низької щільності — на 19,3 % (р &lt; 0,01), тригліцеридів — на 30,6 % (р &lt; 0,05). Спостерігалися зміни рівня адипокінів у плазмі крові: зниження рівня адипонектину з 5,98 ± 0,52 мг/мл до 4,45 ± 0,29 мг/мл (р &lt; 0,01), а також тенденція до збільшення рівня лептину в плазмі крові з 14,6 ± 2,3 нг/мл до 18,12 ± 2,90 нг/мл (р &gt; 0,05). Зміни швидкості пульсової хвилі в аорті та аортального індексу аугментації були статистично незначущими (р &gt; 0,05). Зміни антропометричних показників (ваги, індексу маси тіла, окружності талії і стегон), а також загальної кількості жирової тканини, визначеної методом імпедансометрії, були статистично незначущими (р &gt; 0,05).Висновки. Комбінована цукрознижувальна терапія глімепіридом і метформіном SR упродовж 12 тижнів призвела до статистично значущого покращення вуглеводного та ліпідного обміну, не впливала на антропометричні показники й загальну кількість жирової тканини, запобігала прогресуванню артеріосклерозу великих судин за даними показників жорсткості артеріальної стінки.