Longitudinal Deformation Research Articles

Distal hamstrings tendons mechanical properties at rest and contraction using free-hand 3-D ultrasonography.

Tendon properties impact human locomotion, influencing sports performance, and injury prevention. Hamstrings play a crucial role in sprinting, particularly the biceps femoris long head (BFlh), which is prone to frequent injuries. It remains uncertain if BFlh exhibits distinct mechanical properties compared to other hamstring muscles. This study utilized free-hand three-dimensional ultrasound to assess morphological and mechanical properties of distal hamstrings tendons in 15 men. Scans were taken in prone position, with hip and knee extended, at rest and during 20%, 40%, 60%, and 80% of maximal voluntary isometric contraction of the knee flexors. Tendon length, volume, cross-sectional area (CSA), and anteroposterior (AP) and mediolateral (ML) widths were quantified at three locations. Longitudinal and transverse deformations, stiffness, strain, and stress were estimated. The ST had the greatest tendon strain and the lowest stiffness as well as the highest CSA and AP and ML width strain compared to other tendons. Biceps femoris short head (BFsh) exhibited the least strain, AP and ML deformation. Further, BFlh displayed the highest stiffness and stress, and BFsh had the lowest stress. Additionally, deformation varied by region, with the proximal site showing generally the lowest CSA strain. Distal tendon mechanical properties differed among the hamstring muscles during isometric knee flexions. In contrast to other bi-articular hamstrings, the BFlh high stiffness and stress may result in greater energy absorption by its muscle fascicles, rather than the distal tendon, during late swing in sprinting. This could partly account for the increased incidence of hamstring injuries in this muscle.

SST2 and morphofunctional parameters of the left ventricle in patients with ischemic heart disease with chronic heart failure and previous COVID-19

Objective: to assess the concentration of the sST2 biomarker and its relationship with the morphological and functional parameters of the LV myocardium in patients with coronary artery disease and chronic heart failure (CHF) l-lll functional class (FC), who had and did not have COVID-19. Material and methods. We examined 100 patients (66 males), median (Me) age 65 [63; 67] years, with stable coronary artery disease with CHF l-lll FC (New York Heart Association), divided into 2 groups depending on the COVID-19. Along with the conventional clinical examination, the concentration of serum sST2 was determined by enzyme immunoassay Results. It was found that in patients who underwent COVID-19 (group 1), the sST2 level was 38.4 [35.5; 44.8] ng/ml, in the comparison group (group 2) — 29.63 [27.9; 32.7] ng/ml (p<0.001). In group 1, the final diastolic volume and the final systolic volume of LV significantly exceeded those in group 2 (p=0.004 and p=0.02) and amounted to 118.2 [107.5; 166.5] and 44.1 [35.0; 58.1] ml, respectively, for the 1st and 107.5 [92.4; 129.5] and 37.9 [29.5; 47.4] ml for the 2nd group. The number of patients with grade 2 diastolic dysfunction (DD) in group 1 (18-33.9%) significantly exceeded that in the comparison group (7-14.9%). Changes in global longitudinal deformation of LV in COVID-19 group (-15.6 [-20.8; -13.8]%) were more pronounced than in the comparison group (-19.9 [-21.5; -16.3]%)(p=0.018). Conclusion. CHD patients with CHF l-lll FC and previous COVID-19, have significantly higher serum sST2, more pronounced LV DD and greater global longitudinal deformation.

Longitudinal Stent Deformation at the Proximal Segment of the Left Main Coronary Artery Caused by a Stuck OCT Catheter: Case Report and Review of Literature.

It has been rarely reported that a stuck optical coherence tomography (OCT) catheter can lead to longitudinal stent deformation (LSD). This complication can result in incomplete stent apposition and dissection after stent implantation. In this study, we present a case where a bailout stent was implanted in the distal segment of the left anterior descending artery (LAD) after longitudinal stent deformation caused by a stuck OCT catheter. This approach was taken to prevent acute stent thrombosis, subacute stent thrombosis, in-stent restenosis (ISR), and death. The patients were followed up for one year, and no adverse events were observed.

Myocardial dysfunction in patients with rheumatoid arthritis in the speckle-tracking echocardiography and its relationship with the clinical characteristics of the disease

patients with RA have an approximately 50% increased risk of cardiovascular events and cardiovascular death. Cardiovascular diseases lead to a decrease in life expectancy, and the determination of the mechanisms of myocardial damage in patients with RA is of great importance for the development of methods for the early prevention of heart failure. The aim of our study was to study myocardial dysfunction using speckle tracking echocardiography (STE) in patients with RA and to find out possible correlations with the course of the disease and risk factors for cardiovascular diseases. Materials and methods. 29 RA patients were examined (5 in remission, 17.2%). Rheumatoid factor (RF), the level of antibodies to cyclic citrullinated peptides (a-CRP), quantitative C-reactive protein (CRP) was determined in the blood of all patients, and echocardiography and speckle-tracking echocardiography were performed to determine indicators of longitudinal deformation of the left ventricle. Disease activity was determined using the DAS28 index (CRP) and other functional and laboratory indicators. The results. The study of STE indicators is much better than "classical" echocardiography, revealing latent preclinical heart lesions. We established a significant decrease in Global Longitudinal Strain in the basal anterior and basal antero-septal segments (-17.24±3.01% and 15.94±9.37%, respectively) and preservation of local strain in the apical and middle segments (respectively -26.95+4.95% and -21.69+3.05%). In general, 41.2% of patients with RA had lesions of the basal segments. When analyzing the correlation between disease activity and deformation in STE, an inverse relationship between the DAS28 index and apical deformation (API Strain) was established (r=-0.50, р=0.06). The highest correlations were found between STE and functional status of disease: HAQ-DI score (r=-0.51, p=0.05) and VAS activity (r=-0.64, p=0.01). Conclusions. Functional activity according to the HAQ-DI score and VAS had a significantly greater relationship with preclinical manifestations of heart damage (detected by STE) than standard cardio-vascular risk factors. It is necessary to continue the search for other important factors that can lead to the formation of heart lesions and are related to both the activity of the disease and the functional status of patients. It is expedient to conduct comparative studies of STE in RA and coronary artery disease to clarify the differences in the processes of formation of myocardial damage.

The Balloon-Assisted Double-Kissing T-Stenting Technique: Concept, In Vitro Model, and Case Examples

BackgroundIn complex bifurcation percutaneous coronary intervention, 2-stent strategies are often required. Commonly used 2-stent techniques can lead to suboptimal results due to their complexity. We developed the balloon-assisted double-kissing T-stenting (DKT) technique, which uses balloons to optimize stent placement, delivery, and final architecture. MethodsWith the balloon-assisted DKT technique, a balloon is inflated into the main branch (MB) to identify the best position of the side-branch (SB) stent instead of relying on angiography. DKT aims at supporting the SB ostium with stent crowns instead of distorted open cell(s), by achieving a longitudinal deformation with minimal crush of the SB stent upon implantation of the MB stent. This hypothesis was tested on a bench model. We report how the technique was performed in 2 cases and provide intracoronary imaging of the results. ResultsAs hypothesized, DKT resulted in a longitudinal accordion-like deformation and minimal crush effect on bench. The SB ostium was supported by stent crowns. The SB wall opposed to the carina was well covered with crowns from the MB stent after proximal optimization technique and final kissing. The technique was successfully used in 2 complex left main cases with perfect coverage of the SB ostium as assessed with intracoronary imaging. ConclusionsThe balloon-assisted DKT is a simple technique that combines strengths of double-kissing crush and culotte techniques, results in appropriate SB ostium coverage, and deserves further investigation.

Informativeness of echocardiography in inferior myocardial infarction at different stages of observation

Aim. to evaluate the informativeness of echocardiographic parameters in patients with acute inferior wall myocardial infarction of the left ventricle, who have undergone primary percutaneous coronary intervention, at discharge from the hospital and in the long-term period.
 Material and methods. Echocardiographic data was analyzed using speckle tracking technology in 144 patients with acute inferior myocardial infarction of the left ventricle before discharge and 2 years later. In the post-infarction period, 10 patients underwent magnetic resonance imaging and 15 patients underwent stress echocardiography.
 Results. Using the tree construction method, critical values of 7 ultrasound parameters were identified (for the left ventricle - ejection fraction, end-systolic volume index, global longitudinal and circular strains, for the right ventricle - tricuspid S', global longitudinal strain, free wall strain), which with a probability of 89.4% predict repeat revascularization.
 Identification of possible areas of myocardial fibrosis in the remote period by speckle-tracking echocardiography has a sensitivity of 46-57%, specificity of 68-76%, and negative predictive value of 74-87% relative to the gold standard detection of postinfarction scarring by magnetic resonance imaging.
 According to the results of stress-echocardiography, new zones of local contractility impairment registered after exercise were not accompanied by changes in segmental longitudinal deformation.
 Conclusion. The results of echocardiographic screening of patients with acute inferior myocardial infarction of the left ventricle using speckle tracking technology have high prognostic significance in assessing the likelihood of repeated revascularization at discharge and diagnostic information for verifying post-infarction fibrous changes in the long-term period.

Echocardiographic evaluation of myocardial structural and functional changes in patients with stage 5 chronic kidney disease before and after kidney transplantation

Introduction. Chronic kidney disease, stage 5, leads to structural remodeling of the myocardium, and heart failure. Kidney transplantation promotes normalization of structural and functional parameters of the myocardium through reverse remodeling with an improvement of its systolic function.Aim. To evaluate structural and functional changes of the myocardium in patients before and after kidney transplantation, using echocardiography.Material and methods. A retrospective cross-sectional study included 111 individuals of whom 36 patients underwent evaluation for kidney transplant waiting list placement program (Group I), and 51 patients received kidney transplants from deceased donors (Group II). Group III consisted of 24 individuals without kidney pathology. All patients underwent transthoracic two-dimensional echocardiography using the Phillips Epiq 7 device to determine the structural and functional parameters of the heart, including the use of speckle-tracking technique to assess longitudinal and circumferential myocardial deformation of the left ventricle.Results. There were no statistically significant differences in transthoracic echocardiography results between patients in Group I and Group II. When compared to the parameters of patients in Group III, statistically significant differences were found in the following parameters: volume and volume index of the left atrium, end-diastolic volume index, left ventricular mass index, interventricular septum thickness and posterior wall thickness of the left ventricle, as well as diastolic function parameters (E/A). Patients in Group I and Group II had significantly higher values of left atrium diameter: 32 (26.0;38.0) mmHg and 31.0 (27.3;40.0) mmHg, respectively, (p1-2=0.949), while in Group III this parameter value was 22.5 (20.8;25.3) mmHg (p1-3<0.001, p2-3<0.001). Correlation analysis revealed statistically significant correlations between left ventricular mass index and global circumferential strain (r=0.41, p=0.0027), as well as between E/e' ratio and left ventricular mass index (r=0.323, p=0.00197). It was found that after 3 months post kidney transplantation, there was a decrease in the left atrium diameter, volume, and volume index. The values of left atrium diameter immediately after kidney transplantation and after 3 months were 40 (32.5;45) mmHg and 35 (25.5;41.0) mmHg (p=0.049); those of the left atrium volume were 62.5 (50.0;77.3) and 51.5 (47.5;64.5) ml (p=0.03); and those of the left atrium volume index were 33.4 (29.3;40.2) and 28.3 (25.5;33.6) ml/m2 (p=0.01) respectively.Conclusions. Patients with chronic kidney disease stage 5 have a high incidence of functional and structural abnormalities of the left heart chambers; left ventricular mass index positively correlates with E/e' and global circumferential strain. At 3 months after kidney transplantation, there was a slight positive trend manifested in the form of a decrease in left atrium diameter and a decrease in left ventricle volume. Further dynamic study of this group of patients in the long term after kidney transplantation is planned.

Impact of Multi-Axle Wheelbases on Longitudinal and Transverse Deformations at the Bottom of Bituminous Pavement Layers

Impact of Multi-Axle Wheelbases on Longitudinal and Transverse Deformations at the Bottom of Bituminous Pavement Layers

Research on lateral buckling of eccentrically compressed H-shaped section aluminum alloy perforated members

Aluminum alloy members are widely used in various engineering fields because of the light weight and corrosion resistance. However, the existing research on the stability of the aluminum alloy beam-column with web openings is insufficient. This study carried out the eccentrically compressed tests for 60 H-shaped section aluminum alloy perforated members, taking the opening number, opening diameter, slenderness ratio, and eccentricity distance around major axis as main variables. The tested specimens showed obvious lateral buckling. The effects of web openings on buckling mode, stability bearing capacity, longitudinal deformation, lateral deformation, and strain development of the member are studied. The influence of each variable on the mechanical properties is studied, which provides the basis for design of the structure members. Several main parameters are analyzed in depth using verified finite element model. Based on the results of test and FEA, the design method for lateral stability bearing capacity of H-shaped section aluminum alloy perforated members is proposed with reference to existing specifications.

Dynamics of the Deformable Fluid Interface Interacting with an Approaching Solid under the Electrostatic Field.

A theoretical model was developed to describe the dynamics of a deformable fluid interface interacting with an approaching solid without contact by both the attractive electrostatic and van der Waals (i.e., vdW) interaction, analogous to the situation in the experiments by electric force microscopy (i.e., EFM) or electric-surface force apparatus (i.e., E-SFA) involved in the soft fluid interface. On the basis of this model, a numerical study of the deformation of the fluid interface, the force-vs-separation behavior, and the critical limiting conditions of contact has systematically been carried out. Our results show that the surface pressure induced by the electrostatic interaction plays a more prominent role in the deformation of the fluid interface than the vdW interaction does, and there exists a principal length scale associated with the relative strength of the electrostatic field to the surface tension, affecting the fluid interface shape under the electrostatic field. It was also shown that both the force-distance curves and the corresponding curves of fluid interface deformation peak versus distance for various electrostatic fields satisfy the universal scaling power law. Moreover, an analytical solution to the Euler-Lagrange differential equation governing the deformation of the fluid interface under the external electric field is obtained, and two extended formulas for explicitly describing the principal length scales that respectively characterize the lateral and longitudinal deformations of the fluid interface were determined.

Comparative assessment of myocardial function between late premature newborns and term neonates using the 2D speckle tracking method.

Assessment of myocardial function through speckle tracking echocardiography (STE) can bring benefits to conventional echocardiography in premature newborns, a particular vulnerable group in terms of adaptation to extra-uterine life. Furthermore, it represents a non-invasive imagistic method which can guide therapeutic approach in the hemodynamically unstable newborn. This study aims to highlight the particularities of myocardial function in late premature newborns, by conducting a comparison with a group of healthy neonates, by using STE. Conducted over a timespan of two years, this prospective study enrolled 64 term neonates and 21 premature newborns, with gestational ages ranging between 28 and 36 weeks, who prior to discharge underwent a cardiac ultrasound, involving two-dimensional image acquisitions of the apical four-chamber view of both ventricles. Afterwards, the images were offline analyzed, by using the autostrain function. After segmental strain analysis, no significant discrepancies between the two groups in terms of interventricular values were found. However, left ventricle and right ventricle strain measurements differed significantly (p < 0.01), for each of the analyzed segments (basal, medial or apical). Moreover, a linear increase in interventricular (IV) basal strain with corrected gestational age progression was noted (p = 0.04). Peak global longitudinal strain (pGLS) and EF were similar between the two study groups. Premature newborns presented significantly more negative mean values of right ventricular free wall longitudinal strain (RVFWSL), (-24.19 ± 4.95 vs. -18.05 ± 5.88, p < 0.01) and of right ventricle global four chamber longitudinal strain (RV4CSL), (-19.71 ± 3.62 vs. -15.46 ± 5.59, p < 0.01), when compared to term neonates. The 2D STE is a reliable method for cardiac assessment of late preterm newborns. The evaluation of two-dimensional global longitudinal LV and RV strains might represent a useful tool in clinical practice. A better response of the right ventricle to the longitudinal deformation within premature neonates was noted. Thus, this study facilitates the identification of accurate reference values for this particular population segment, which will enable the evaluation of ventricular function in premature newborns with concurring disorders. Future longitudinal studies, assessing the fetal heart, could provide more insight into the development of myocardial function.

Evaluation of post-dilatation on longitudinal stent deformation and postprocedural stent malapposition in the left main artery by optical coherence tomography (OCT): an in vitro study

BackgroundThe diameter of the ostial and proximal left main coronary artery can be greater than 5.0 mm. However, the diameters of the mostly available coronary drug-eluting stents (DESs) are ≤ 4.0 mm. Whether high-pressure dilatation can increase the diameter of stents from 4.0 to 5.0 mm and whether post-dilatation leads to longitudinal stent deformation (LSD) of 4.0-mm-diameter stents have rarely been studied. Therefore, this study aims to evaluate LSD and stent malapposition of six types of commercially available 4.0-mm-diameter stents in China in a 5.0-mm-diameter artificial blood vessel model by optical coherence tomography (OCT) in vitro.MethodsThe left main coronary artery was simulated by a truncated cone-shaped silicone tube. The internal diameters were 4.0 mm at one end of the silicone tube and 5.0 mm at the other end. Six different types of coronary stents widely used in China were selected for this study. Each stent was respectively implanted into the simulated blood vessel and dilated to a diameter of 4.2 mm according to the stent-balloon pressure compliance table. The stents were subjected to post-dilatation with a 5.0 × 15-mm noncompliant balloon. The LSD ratio of the longitudinal axis of each stent and stent malapposition were measured through OCT, and any fractures of the stents were determined.ResultsNone of the six types of stents fractured following post-dilatation. The longitudinal axes of the BuMA and Excrossal stents were slightly shortened, while the other stents were elongated after high-pressure post-dilatation. All stents expanded to a diameter of 5.0 mm without incomplete stent apposition, except for the Nano Plus stent, which remained malapposed after high-pressure post-dilatation.ConclusionAll 4.0-mm-diameter stents can be expanded to a diameter of 5.0 mm by noncompliant balloon post-dilatation without stent strut fracture. Most stents were found to be well apposed after high-pressure post-dilatation. However, LSD was observed after post-balloon dilatation. Stent malapposition might be positively correlated with the percentage change in stent length.

Arch First and Beam Later Technology: An Accelerated and Safe Construction for Tied Arch Bridges

The Taidong River Bridge, a 115 m tied arch bridge, was opened in 2021 over the Taidong River in Jiangsu, China. Due to the significant role of the Taidong River as a crucial navigation channel for local transportation, construction activities aimed to reduce the duration of river closure. The bridge construction employed the pioneering technique of arch first and beam later without support mechanisms in the river course. This method entailed the integral hoisting of arch ribs via a floating crane, and the tied-arch bridge's longitudinal deformation was temporarily consolidated with tension during construction phases. The investigation analyzes the hoisting point layouts, arch rib limiting devices, structural system transformations implemented, as displacement, and horizontal thrust of the arch foot during the temporarily consolidated tensioning construction stage of the bridge. The research results showed that the arch first and beam later method without support construction adopted in this project demonstrated impressive compliance with the navigation standards stipulated for the Taidong River. In addition, this study proposes a method that combines mechanical calculation formulas with the Midas model to determine the position of the arch rib suspension point and provide theoretical values for temporary consolidation forces during the construction stage. The findings of this study offer valuable practical guidance that can be applied to comparable bridge projects.

Regulating the electrical performance of contact-separation mode triboelectric nanogenerators based on double-sided groove textures

The contact-separation mode triboelectric nanogenerators (CS-TENGs) is a kind of micro/nano electromechanical power system based on the contact electrification and electrostatic induction. With the expansion of application field of the CS-TENG, regulating the electrical performance becomes essential. In this paper, simple and effective methods for the CS-TENG output regulation based on the double-sided groove textures are proposed. To do this, groove textures on both Cu contact electrode and PDMS dielectric layer are fabricated, and influences and mechanisms of the alignment angle (the angle between the direction of groove textures on the Cu electrode and that on the PDMS dielectric layer), matching condition (textures sidewall contact and non-contact) and applied pressure on the CS-TENG output are explored through output tests, contact and electrostatic simulations. It is shown that altering the alignment angle, matching condition and applied pressure of groove texture on the Cu contact electrode and PDMS dielectric layer, could simply regulate the output of CS-TENG, where changing the alignment angle is the most effective. Under low and high applied pressures, the variations of the output voltage with alignment angle from 0˚–90˚ reach to 343.8% and 297.2%, respectively, and CS-TENG at 0˚ angle outputs the maximum voltage under both pressures, while the minimum voltages under the two pressures are exhibited from different angles. The change of contact area induced by the longitudinal deformation and transverse expansion of the groove textures is the main reason for the output regulations.

Study of longitudinal deformation profiles in high-ground-stress mega-section tunnels based on the Hoek–Brown criterion

In rock tunnel construction, the analysis of rock deformation characteristics is an essential aspect of the overall safety evaluation. In this study, the high-ground-stress section of the Tongzi tunnel was taken as the research object and the longitudinal wave velocities of the disturbed and undisturbed areas of the surrounding rock were measured using on-site drilling to determine the disturbance range of the surrounding rock excavation. The uniaxial and triaxial compressive strengths of the rocks sampled in the field were measured through indoor tests. Through a combination of the field acoustic test and indoor test results, the Hoek–Brown (H-B) failure criterion parameters of the surrounding rock were quantitatively obtained. A numerical model was developed for the analysis, and the following conclusions were drawn: At the pre-deformation stage, the influence of the crown settlement, horizontal displacement, and the tunnel face extrusion deformation were all within the range of one times the tunnel diameter. The location and area of the first tunnel face influenced the extent of the surrounding rock’s pre-deformation. A more pronounced effect on the pre-deformation of the tunnel crown settlement was obtained the closer the first tunnel face was to the tunnel crown. In addition, the closer the first tunnel face was to the arch waist, the more pronounced the impact was on the pre-deformation of the horizontal displacement, and the pre-deformation increased exponentially with the increase in the significance of the excavation area of the first tunnel face. The deformation varied in tunnels that had been excavated using different construction methods. The three-step method employed in this study resulted in the most considerable deformation, followed by the CD method, and the double-side heading method resulted in the smallest deformation. The results show that increasing the number of working faces and using small cross-sectional staggered slot excavation are beneficial to tunnel stability. The field monitoring data are generally consistent with the numerical simulation results, providing a degree of validation for the numerical simulation results. The intrinsic model used in the numerical simulation influences the simulation results. When compared with the Hoek–Brown principal structure model, using the Mohr–Coulomb central structure to simulate the high-ground-stress rock tunneling may result in more considerable elevation arch uplift and tunnel face extrusion deformation. Therefore, it is more reasonable to use the Hoek–Brown principal structure model.

Investigations of stress and strain state of aluminum alloys during a hot extrusion and patterns of structure and feature formation

This paper investigates the stress and strain state as well as formation processes of structure and features of aluminum alloys during the hot extrusion. It has been shown that during the hot extrusion the ring layers of an extruded element experience not only longitudinal and transverse deformations, but also a slip. The slip increases from inner layers to the surface layer. The tensile principal stresses and the sum of slip deformations also increase. It has been also demonstrated that at the exit of the pressing part the tensile principal stresses have different directions, forming an angle with extruder axis, which also increases towards the surface. In conclusion, it has been stated that the main radial and circumferential deformations act as restraining deformations.

New nonlinear models of dynamic longitudinal deformation of a viscoelastic rod

In this paper we study a general model of dynamic longitudinal deformation of a viscoelastic rod with a nonlinear dependence of the stress on the strain and on the strain rate. This model is given by a nonlinear differential equation with partial derivatives of the third order. A group classification of this model which depends on two arbitrary functions is carried out. Six basic models are obtained, for which their main Lie groups of transformations are found. A model that admits the widest Lie group of transformations is studied in detail. For it, formula for the production of new solutions is obtained and all invariant submodels are found. For all its invariant submodels, the invariant solutions defining these submodels are found either in explicit form, or their search reduces to solving the systems of first-order differential equations. For these systems, boundary value problems that have a physical meaning are studied. Conditions are obtained that ensure the existence and uniqueness of solutions to these boundary value problems. This allows one to correctly solve these boundary value problems numerically. Boundary value problems for some specific values of the parameters included in them are solved numerically. The research carried out is especially relevant in rocket engineering, aircraft engineering, shipbuilding and other fields.

The effectiveness of hardware CPAP therapy in heart failure with preserved left ventricular ejection fraction and obstructive sleep apnea syndrome

Aim. To evaluate the effectiveness of hardware Continuous Positive Airway Pressure therapy (CPAP therapy) and its likely predictors in patients with heart failure with preserved ejection fraction (HFpEF) associated with obstructive sleep apnea syndrome (OSAS).&#x0D; Materials and methods. The study involved 207 men with HFpEF and OSAS (apnea/hypopnea index 15 per hour) who did not initially have ischemic disease and other structural heart pathology. At inclusion in the study, polysomnography and echocardiography were performed with an assessment of diastolic function and global longitudinal deformation of the left ventricular myocardium, as well as a 6-minute walk test (6MWT) and the level of the brain natriuretic peptide precursor (NT-proBNP) in the blood was determined. 80 patients received hardware CPAP the rapy, 127 patients made up the control group. After 12 months, 6MWT was repeated, NT-proBNP was determined, and clinical outcomes were assessed retrospectively.&#x0D; Results. The CPAP group had 16% fewer hospitalizations (p=0.011 [95% confidence interval – CI 4.29]) and showed a trend towards an increase in the 6MWT distance (p=0.065). To assess the likely predictors of the effectiveness of CPAP therapy, a subgroup of “responders” was identified, characterized by an increase in the distance according to the 6MWT, a decrease in the level of NT-proBNP, and the absence of adverse clinical events during the observation period. There were significant differences between responders and non-responders in apnea/hypopnea index (p=0.01 [95% CI -10.6; -2.5]), global longitudinal deformation of the left ventricular myocardium (p=0.05 [95% CI -4.7; 0]), diastolic function E/A (p=0.02 [95% CI -0.1; 0]).&#x0D; Conclusion. CPAP therapy improves clinical outcomes and functional status in patients with OSAS-associated HFpEF. The predictive model built using the identified efficacy predictors can be used to develop a personalized treatment algorithm for this cohort of patients.

Possibilities of predicting early postoperative complications after surgical correction in infants of the first year of life with ventricular septal defect

Objective. To study the echocardiographic (Echo-CG) indicators in infants of the first year of life with ventricular septal defect (VSD) in the early postoperative period after surgical correction of the defect.&#x0D; Materials and methods. Examination of 205 infants with VSD was carried out. Complex examination before the surgery, 6, 24 hours and the day 10th after the surgery was fulfilled.&#x0D; Results. In the early postoperative period, myocardial dysfunction (MD) was detected in 30.2 % of cases (n = 62). The patients were longer subjected to artificial lung ventilation (p = 0.04), had a longer period of staying in the intensive care unit (p = 0.002) and hospital (p = 0.004). The data, predicting the postoperative MD were revealed including VSD area index (OR 2.7; р = 0.00001), longitudinal deformation of the left ventricle (SLV; OR 2.69; р = 0.00001), longitudinal deformation of the free wall of the right ventricle (SRV; OR 1.04; р = 0.0001) and the average estimated pressure in the lung artery (OR 1.6; р = 0.0001).&#x0D; Conclusions. 1. After the surgery, MD was detected in 30.2 % of cases. 2. SLV and SRV in infants with MD demonstrate the aggravation of ventricular contractility earlier than traditional indicators of the systolic function. 3. Preoperative SLV «–» 12 %, SRV «–» 6 %, VSD area index 100,5 mm2/m2, average estimated pressure in the lung artery 38 mm Hg are independent predictors of complications accompanied by MD during the first day after the VSD closure. 4. Complications, connected with longer ALV, are associated with duration of staying in the intensive care unit and hospital.

Possibility of Monitoring the Dynamic Impact of the Rolling Stock on the Track Superstructure Using Strain Gauges and Vibrometry

One of the priority tasks in development of railway transport is to raise its efficiency by increasing the time between repairs for both the track superstructure and the rolling stock. Solving this problem is impossible without timely, complete, and reliable information about the dynamics of interaction of the rolling stock with the infrastructure. To organise monitoring of dynamic processes, completely different types of primary transducers are used: resistance strain gauges, fibre-optic sensors, dynamometers (force sensor pads), accelerometers, acoustic emission sensors. This implies relevance of the scientific and technical problem of comparative testing of sensors of different types to assess the information content of their signals and justify the criteria for choosing primary transducers when solving specific monitoring problems.The objective of the study is to comparatively test removable resistive strain sensors, optical polarisation strain sensors and accelerometers under a passing train and to evaluate their information content to control rail depression and detect defects on the running surface of wagon wheels.The study using finite element modelling and a physical model of a rail as of a beam on an elastic foundation, substantiates the relationship between longitudinal deformations and vertical accelerations of the rail foot. Comparative tests of removable strain-resistive and optical polarisation strain sensors and accelerometers were held on an experimental section of track under a passing train. A signal processing algorithm has been developed and the equivalence of strain gauges and vibrometers for determining the depression of a rail under a passing train has been proven. Acomparison has been made of the pulse components of the signals of deformation and vibration acceleration during movement of a wheel with a defect on the running surface, and the requirements for the frequency characteristics of the sensors and their mounting on the rail surface have been substantiated.