bluuebunny/crossref_metadata_2025 huggingface dataset:
The use of reliability indicators in the design of die tooling of technological processes of hot die forging
Authors: Kutyshkin A V , Shashok A V , Brylova T B
Published: February 2021

The article discusses the use of a number of indicators of the reliability of the functioning of the hot forming process to substantiate the choice of the number of die inserts (die streams) and selection of grades of tool steels for their manufacture. There are such used reliability indicators as the probability of the absence of typical defects in the shape of the stamped forgings, the probability of predominant types of exploitative refusals of the stamp, and the absence of failures in the implementation of the technological process as a whole. The rationale for the expediency of choosing a pre-stream of the die for stamping an axisymmetric forging with a high degree of complexity taking into account the possibility of occurrence of such shape defects as clamping, shooting, and incomplete forging radii during stamping, is considered. When the choice of the grade of tool steel for die inserts was taken into account, there was the occurrence of such typical types of their exploitative refusals as adhesion wear of die streams, the formation of hot cracks and plastic crushing of the forming elements of the stamp streams. The appropriate organizational and technical decisions are adopted on the basis of a comparison of cost indicators characterizing the production costs due to scrap forgings. They are caused by the formation of shape defects during stamping and the occurrence of exploitative refusals of dies. In addition, there are the costs for the manufacture of more complex die tooling and its exploitation, i.e. production quality costs.
Development and justification of parameters of a microwave installation for pre-planting treatment of vegetable seeds
Authors: Mikhailova O V , Novikova G V , Belova M V , Kotin A I , Kazakov A V , Tikhonov A A
Published: February 2021

The article is devoted to the analysis of the dielectric parameters of potato and onion tubers for the development of a microwave installation that provides pre-planting treatment by means of a complex effect of electrophysical factors. The sources of energy were magnetrons, Ultratone or Darsonval. The originality of the research includes analysis of the volume of planting material for determination of the required plant performance; analysis of the dielectric parameters of potatoes depending on the frequency of EMF, humidity, and temperature for calculating the power of dielectric losses per unit volume. Theoretical studies of the dielectric parameters of onions presented their structure as a “capillary model”. The development of the design of a microwave installation for provides a complex effect of electrophysical factors when calibrating onions. The justification of the corona discharge intensity of electric-gas-discharge lamps is in UHFEMF. There is the study of the dynamics of onion-sowing heating, justification of effective treatment modes. The dynamics of onion heating shows that with the power of the microwave generators of 3.4 kW and Darsonval of 80 W, the drum drive power of 0.25 kW, it is possible to ensure the installation capacity of 150-200 kg/h at an energy cost of 0.025 kWh/kg.
Mathematical model of a journal bearing with low-melting and porous coating in its structure on different contacting surfaces with incomplete filling of operating clearance
Authors: Mukutadze M A , Morozova A V , Opatskikh A N , Zadorozhnaya N S
Published: February 2021

The authors consider the development of a mathematical design model of an infinite journal bearing lubricated with a lubricant with Newtonian rheological properties and a melt of a low-melting metal alloy covering the surface of the bearing bush, as well as a porous coating on the surface of the shaft, taking into consideration the dependence of the viscosity characteristics of the lubricant, the melt and the permeability of the porous coatings on the pressure with incomplete filling of the operating clearance. The authors found asymptotic solution of the system of differential equations with respect to the parameter K due to the melt and the rate of dissipation of mechanical energy and the exact self-similar solution for the zero approximation without regard for the melt and the first approximation taking into consideration the melt. This solution was found according to the equation of motion of a viscous incompressible fluid for a thin layer, the equations of continuity, Darcy equation and the equation determining, taking into account the expression for the rate of dissipation of mechanical energy, the profile of the molten contour of the bearing bush with regard to the dependence of the permeability of the porous coating, the viscosity of the lubricant depending on pressure. As a result, the fields of velocities and pressures in the lubricating and porous layers were determined taking into consideration the dependence of the lubricant viscosity and the permeability of the porous coating on pressure, as well as the function Φ1(θ), reasoned by the melt of the bearing bush surface. In addition, the main performance characteristics were determined: load-bearing capacity and friction force.
Scientific and methodological basic principles for determining design of clay acid treatments applied to wells
Authors: Akhmetshina D I , Mukhametshin V V , Kuleshova L S , Batalov D A
Published: February 2021

A new methodological approach is presented in determining design of current clay acid treatments of wells. The proposed scientific and methodological approach allows differentiating for different groups of objects in the Langepass region to determine certain technological parameters of impact on the bottom hole zone of formations, taking into account the features of geological and physical properties of formations and fluids saturating them. In special cases, it is suggested to use acid retarders for reaction with rock. The authors proposed algorithm for determining wells where the maximum effect can be obtained at a specific time.
Thermomanometric system for diagnosing the technical condition of the ESP by the level of its vibration
Authors: Zainagalina L Z , Dumler E B
Published: February 2021

The article presents the results of the analysis of the main vibration causes of a submersible electric centrifugal pump and its consequences. It gives recommendations for minimizing the vibration with the installation of an electric centrifugal pump (ESP). The article analyzes the problem of breaks’ occurrence in the submersible unit assemblies is a result of the influence of various factors during the operation of the ESP. This type of failure is the most dangerous, since the fall of equipment to the bottom of the well is accompanied by damage to pump unit assemblies, cable rupture, jamming of equipment in the casing, and blockage of the filtration zone. Elimination of such accidents is characterized by significant costs for lifting the fallen equipment and restoring the bottom of the well, while the economic losses associated with an increase in the volume of work and the time of the forced downtime of the well increases significantly. The research identifies a number of reasons causing the accident, carries out the analysis of existing techniques and methods of eliminating “flights”, and proposes a telemetry device to solve this problem.
Bulk and interface second harmonic generation in the Si3N4 thin films deposited via ion beam sputtering
Authors: Das Nirmal Kumar , Kanclíř Vít , Mokrý Pavel , Žídek Karel
Published: February 2021

The nonlinear optical second harmonic generation (SHG) in Si3N4 has attracted considerable attention due to a variety of promising applications in optoelectronics. However, reports on SHG in Si3N4 thin films and microstructures lead to diverse conclusions about the SHG origin, pointing towards the Si3N4 bulk, as well as to the Si3N4–Si interface. Here we report on the measurement of polarization-resolved angle-dependent SHG in Si3N4 thin films in the reflective mode. This mode allowed us to measure the nonlinear response of Si3N4 thin films on the Si single crystal substrate. By measuring three samples deposited via ion beam sputtering, we were able to analyze the bulk and interface contributions. We have demonstrated that apart from the bulk SHG, the Si3N4–Si interface contributes with a significant amount of SHG for the thin sample (600 nm). Our result provides a link between the previous measurements in the Si3N4 thin films and on the microstructures.
Simulation of carriers spatial distribution and transportation in co-mixing composition perovskite for solar cell
Authors: Li Guangdong , Zou Xiaoping , Cheng Jin , Yu Xing , Zhou Zixiao , Wang Junqi , Liu Baoyu , Chen Dan
Published: February 2021

A planar device structure FTO/TiO2/SnO2/Cs0.1[HC(NH 2)2]0.74(CH3NH3)0.13PbI2.48Br0.39(Cs0.1FA0.74MA0.13PbI2.48Br0.39)/CuSCN/Au with cation and anion co-mixed Cs0.1FA0.74MA0.13PbI2.48 Br0.39 as light harvester was modeled and investigated by using modeling program wxAMPS. The energy band structure, carrier concentration, carrier generation rate, recombination rate, and other data were obtained through simulation to analyze the specific influence on the performance of perovskite solar cells (PSCs). In order to better optimize device performance, we investigated the effects of perovskite and the interface between each functional layer defect density, film thickness, and test temperature environment on the performance of PSCs. The simulation results show that the device performance has higher dependence on the effect of perovskite and interface defect density. By further optimizing the parameters of defect density (1013 cm−3), film thickness (400 nm), and test temperature (300 K), the power conversion efficiency (PCE) of the finally obtained PSCs was enhanced from the initial 11.65% to 21.95%. This investigation will enable us to better understand the internal working mechanism of PSCs and provide theoretical guidance for the fabrication of high-performance PSCs in experiments.
Effects of nitrogen element on microstructure and pitting corrosion resistance of duplex stainless steel welded joints
Authors: Zhang* Yingying , Liu* Zhengjun , Jin Meiling , Song Shuang
Published: February 2021

The microstructure, element distribution and pitting corrosion resistance of Gas Tungsten arc welding (GTAW) duplex stainless steel welded joints under 100% argon (Ar) and 98% Ar + 2% nitrogen (N2) shielding gas were studied by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and electrochemical corrosion methods. These results show that the addition of N2 to the shielding gas promotes the formation of austenite (γ) phase in the weld joint. Also, the austenite phase distribution is dendritic and the ferrite (δ) and austenite phases in the heat-affected zone are no longer banded structures. Moreover, the austenite phase in the welded joint is enriched in nickel (Ni) and nitrogen (N) elements, while the ferrite phase is enriched in chromium (Cr) and molybdenum (Mo) elements. The pitting corrosion index (PREN) of the austenite/ferrite (δ/α) phase boundary is lower than that of δ and γ phases, which leads to their preferential corrosion. The appearance of chromium nitride (Cr2N) decreases the corrosion resistance of the weld seam and the heat affected zone. N2 in the 98% Ar + 2% N2 shielding gas can restrain Cr2N precipitation, increase the pitting corrosion index of secondary austenite structure (γ
2), and improve the pitting corrosion resistance of welded joints.
Modification of TiO2 with metal chalcogenide nanoclusters for hydrogen evolution
Authors: Rhatigan Stephen , Niemitz Lorenzo , Nolan Michael
Published: February 2021

Using density functional theory, corrected for on-site Coulomb interactions (DFT + U), we have investigated surface modification of TiO2 with metal chalcogenide nanoclusters for hydrogen evolution. The nanoclusters have composition M4X4 (M = Sn, Zn; X = S, Se) and are adsorbed at the rutile (110) surface. The nanoclusters adsorb exothermically, with adsorption energies in the range −2.8 eV to −2.5 eV. Computed density of states (DOS) plots show that cluster-derived states extend into the band-gap of the rutile support, which indicates that modification produces a redshift in light absorption. After modification, photoexcited electrons and holes are separated onto surface and cluster sites, respectively. The free energy of H adsorption is used to assess the performance of metal chalcogenide modified TiO2 as a catalyst for the hydrogen evolution reaction (HER). Adsorption of H at nanocluster (S, Se) and surface (O) sites is considered, together with the effect of H coverage. Adsorption free energies at cluster sites in the range −0.15 eV to 0.15 eV are considered to be favourable for HER. The results of this analysis indicate that the sulphide modifiers are more active towards HER than the selenide modifiers and exhibit hydrogen adsorption free energies in the active range, for most coverages. Conversely, the adsorption free energies at the selenide nanoclusters are only in the active range at low H coverages. Our results indicate that surface modification with small, dispersed nanoclusters of appropriately selected materials can enhance the photocatalytic activity of TiO2 for HER applications.
Nano-mediated uniform ternary Cu–Co–Ni-based nitrogen-doped carbon nanotubes with synergistic reactivity for high-performance oxygen reduction
Authors: Gao Cunyuan , Huai Jie , Ma Kongshuo , Lu Yizhong , Zhao Zhenlu
Published: February 2021

Here, we report nano-mediated Cu–Co–Ni-based nitrogen-doped carbon nanotubes (N-CNTs/T-CCN) by hydrothermal and procedural calcination strategy. The nitrogen-doped carbon nanotubes (N-CNTs) show more average diameter and the N-CNTs are uniformly modified with ternary Cu–Co–Ni-based nanoparticles (T-CCN). The hybrid exhibits excellent ORR catalytic activity. The onset potential (Eonset) and half-wave potential (E1/2) are 0.96 V and 0.87 V (versus reversible hydrogen electrode, RHE) in 0.1 M KOH. Most importantly, compared to 20% Pt/C, N-CNTs/T-CCN catalyst displays better methanol tolerance and higher stability. The H2O2 yield of the N-CNTs/T-CCN is less than 7.5% and the electron-transfer number (n) is about 3.9. High ORR performance may be related to the synergistic enhancement effect. The N-CNTs supply good electrical conductivity and allow large numbers of active sites to efficiently participate; the T-CCN can improve the local work function of the N-CNTs by synergistic electronic interaction and promote O2 adsorption; the stability of embedded T-CCN can be greatly improved, mainly due to the weakness of Ostwald effect. All these advantages make the hybrid a promising ORR catalyst.
Leukocyte immunoglobulin-like receptor subfamily B: therapeutic targets in cancer
Authors: Deng Mi , Chen Heyu , Liu Xiaoye , Huang Ryan , He Yubo , Yoo Byounggyu , Xie Jingjing , John Samuel , Zhang Ningyan , An Zhiqiang , Zhang Cheng Cheng
Published: February 2021

Inhibitory leukocyte immunoglobulin-like receptors (LILRBs 1–5) transduce signals via intracellular immunoreceptor tyrosine-based inhibitory motifs that recruit phosphatases to negatively regulate immune activation. The activation of LILRB signaling in immune cells may contribute to immune evasion. In addition, the expression and signaling of LILRBs in cancer cells especially in certain hematologic malignant cells directly support cancer development. Certain LILRBs thus have dual roles in cancer biology—as immune checkpoint molecules and tumor-supporting factors. Here, we review the expression, ligands, signaling, and functions of LILRBs, as well as therapeutic development targeting them. LILRBs may represent attractive targets for cancer treatment, and antagonizing LILRB signaling may prove to be effective anti-cancer strategies.
Breath analysis for the detection of digestive tract malignancies: systematic review
Authors: Hintzen K F H , Grote J , Wintjens A G W E , Lubbers T , Eussen M M M , van Schooten F J , Bouvy N D , Peeters A
Published: February 2021

Background

In recent decades there has been growing interest in the use of volatile organic compounds (VOCs) in exhaled breath as biomarkers for the diagnosis of multiple variants of cancer. This review aimed to evaluate the diagnostic accuracy and current status of VOC analysis in exhaled breath for the detection of cancer in the digestive tract.

Methods

PubMed and the Cochrane Library database were searched for VOC analysis studies, in which exhaled air was used to detect gastro-oesophageal, liver, pancreatic, and intestinal cancer in humans, Quality assessment was performed using the QUADAS-2 criteria. Data on diagnostic performance, VOCs with discriminative power, and methodological information were extracted from the included articles.

Results

Twenty-three articles were included (gastro-oesophageal cancer n = 14, liver cancer n = 1, pancreatic cancer n = 2, colorectal cancer n = 6). Methodological issues included different modalities of patient preparation and sampling and platform used. The sensitivity and specificity of VOC analysis ranged from 66.7 to 100 per cent and from 48.1 to 97.9 per cent respectively. Owing to heterogeneity of the studies, no pooling of the results could be performed. Of the VOCs found, 32 were identified in more than one study. Nineteen were reported as cancer type-specific, whereas 13 were found in different cancer types. Overall, decanal, nonanal, and acetone were the most frequently identified.

Conclusion

The literature on VOC analysis has documented a lack of standardization in study designs. Heterogeneity between the studies and insufficient validation of the results make interpretation of the outcomes challenging. To reach clinical applicability, future studies on breath analysis should provide an accurate description of the methodology and validate their findings.
Advances in the management of generalized convulsive status epilepticus: what have we learned?
Authors: Neligan, Aidan , Rajakulendran Sanjeev , Walker Matthew C
Published: February 2021

Convulsive status epilepticus is the most serious manifestation of an epileptic diathesis. In the early stages (5–30 min), there exists class A evidence to support the efficacy of benzodiazepines as first-line treatment. As status epilepticus progresses into the later stages, the evidence for treatment becomes less robust until we are depending upon short case series and case reports for the treatment of refractory status epilepticus. However, the past year saw the publication of three randomized controlled trials in the setting of benzodiazepine-resistant established convulsive status epilepticus: the EcLiPSE and ConSEPT studies, compared levetiracetam to phenytoin in children; and the ESETT study compared fosphenytoin, levetiracetam and sodium valproate in adults and children. In addition, the emergence of data from the SENSE study, a multicentre multinational prospective cohort study and the publication of a systematic review and meta-analysis of the mortality of status epilepticus over the past 30 years, has brought the treatment of status epilepticus into sharp focus. In this update we provide a detailed analysis of these studies and their impact on clinical practice. We review contentious areas of management in status epilepticus where a consensus is lacking and advance the case for more research on existing and alternative treatment strategies.
Optimized Chromatographic Determination of Naphazoline and Chlorpheniramine in Eye/Nose Drops Using Cation-exchange Column
Authors: Reid Imad Osman Abu
Published: February 2021

A simple and efficient liquid chromatographic method has been developed and validated for the simultaneous determination of naphazoline and chlorpheniramine in eye/nose drops, in presence of naphazoline degradation product and naphthalene acetic acid (NAPD). The separation was achieved within 6.0 min, employing a mixture of 53.5% v/v water-acetonitrile containing 78.70 mM/L sodium dihydrogen orthophosphate adjusted to pH 5.30 as isocratic mobile phase, pumped at 1.0 mL/min through a strong cation-exchange column (10 μm particle size), the analytes were monitored at 230 nm. Statistical experimental designs and graphic representations (response surface methodology) were used for optimizing the chromatographic separation. The linearity plots were linear over concentration range up to 125% of the analytes nominal concentrations (100%) with regression coefficients (r) > 0.99, method’s accuracy (RSD < 2.0%), repeatability and intermediate precision (RSD < 2.0%) were verified. System suitability parameters were also within the acceptable range. The validated method was successfully employed for the routine analysis of eye/nose drops.
Amphibian reproductive technologies: approaches and welfare considerations
Authors: Silla Aimee J , Calatayud Natalie E , Trudeau Vance L
Published: February 2021

Captive breeding and reintroduction programs have been established for several threatened amphibian species globally, but with varied success. This reflects our relatively poor understanding of the hormonal control of amphibian reproduction and the stimuli required to initiate and complete reproductive events. While the amphibian hypothalamo–pituitary–gonadal (HPG) axis shares fundamental similarities with both teleosts and tetrapods, there are more species differences than previously assumed. As a result, many amphibian captive breeding programs fail to reliably initiate breeding behaviour, achieve high rates of fertilization or generate large numbers of healthy, genetically diverse offspring. Reproductive technologies have the potential to overcome these challenges but should be used in concert with traditional methods that manipulate environmental conditions (including temperature, nutrition and social environment). Species-dependent methods for handling, restraint and hormone administration (including route and frequency) are discussed to ensure optimal welfare of captive breeding stock. We summarize advances in hormone therapies and discuss two case studies that illustrate some of the challenges and successes with amphibian reproductive technologies: the mountain yellow-legged frog (Rana muscosa; USA) and the northern corroboree frog (Pseudophryne pengilleyi; Australia). Further research is required to develop hormone therapies for a greater number of species to boost global conservation efforts.
Impact on actual clinical practice of the latest evidence for percutaneous closure of patent foramen ovale associated with stroke. A single center experience
Authors: Carnero Montoro L , Ruiz Ortiz M , Paredes Hurtado N , Delgado Ortega M , Rodriguez Almodovar A , Segura Saint-Gerons JM , Mazuelos Bellido F , Ochoa Sepulveda JJ , Valverde Moyano R , Romero Moreno MA , Pan Alvarez-Ossorio M , Mesa Rubio MD
Published: February 2021

Funding Acknowledgements

Type of funding sources: None.

Background and aims

Since september 14th, 2017. Three large clinical trials demonstrated that, in selected patients, percutaneous closure of patent foramen ovale (PFO) was associated with lower recurrence in patients with cryptogenic stroke (CS). Our aim was to determine the impact of these findings on routine  clinical practice in a tertiary hospital.

Methods

Patients with percutaneous closure of PFO due to CS (January 2001-January 2020) were included. The clinical characteristics were analyzed individually and grouped in the RoPE score, before and after the publication date. Complex anatomy (CA) defined as interatrial septum aneurysm or basal wide bubble passage was evaluated in both periods.

Results

293 patients were included. The mean age was 49 ± 11 years, 15% were older than 60 years, 60% men, 26% hypertensive, 28% smokers and 7%diabetics. The median RoPEscore was 6 [p25-75, 5-7] and 75% met CA criteria.

Since september 14th, 2017, the frequency of CA and the mean age of the patients were significantly higher (89% vs. 69% p <0.0005 and 51 ± 11 vs. 48 ± 11 years, p = 0.02, respectively), and RoPEscore, significantly lower (5 [5-7] vs. 6 [5-7], p = 0.02).

Conclusion

The publication of clinical trials wich demonstrated the benefit of percutaneous closure of PFO in CS had a significant impact on the daily clinical practice of our institution, with an increase in indications for CA, despite a clinical profile suggestive of lower causal probability of PFO.
Impaired atrial electromechanical coupling in lichen planus patients
Authors: Jafaripour I , Aryanian Z , Hosseinzadeh S , Pourkia R , Ansari Ramandi MM , Kebria Shirzadian A , Tirgar Tabari S , Pourkia M
Published: February 2021

Funding Acknowledgements

Type of funding sources: None.

Introduction

Lichen planus (LP) which is a chronic inflammatory disease can cause impaired atrial electromechanical coupling, leading to increased risk of atrial fibrillation.

Purpose

The present study aimed to evaluate atrial electromechanical coupling in LP patients by using electrocardiography (ECG) and echocardiography.

Methods

Forty-six LP patients were investigated in this cross-sectional case-control study. The control group comprised healthy individuals selected in age and gender-matched manner. Echocardiography and ECG were done for all patients to show inter and intra-atrial electromechanical delays and P wave dispersion respectively. The electromechanical delays were calculated by using the difference between the delays from the onset of the P wave on ECG to the onset of A wave on tissue Doppler recordings of the different areas.

Results

The baseline characteristics of the case and control group were similar and did not differ significantly. The P wave dispersion was 45.63 ± 3.48 milliseconds in the LP group in comparison to 36.56 ± 2.87 milliseconds in the control group (p < 0.001). As shown in the table, the intra and inter-atrial electromechanical delays were also significantly prolonged in LP patients when compared to the control group (p < 0.001). There was no significant difference between the left and right ventricular systolic function and diastolic function of the two groups.

Conclusion

The results of the study indicate the presence of significant impaired atrial electromechanical coupling in patients with LP confirmed by both electrocardiographic and echocardiographic tools.

Electromechanical delays Case N = 46 (mean ± SD) Control N = 46 (mean ± SD) P value Septal - PA (msec) 59.71 ± 13.24 44.39 ± 11.07 0.002 Lateral - PA (msec) 55.71 ± 13.26 48.89 ± 11.21 0.009 Tricuspid - PA (msec) 52.37 ± 13.12 43.28 ± 10.58 0.002 Inter-atrial delay (msec) (lateral PA−RV PA) 8.47 ± 1.62 6.37 ± 1.36 <0.001 Intra-atrial delay (msec) (LA) [lateral PA−septal PA] 4.80 ± 1.48 3.83 ± 0.82 <0.001 Intra-atrial delay (msec) (RA) [septal PA−RV PA] 3.91 ± 0.96 2.02 ± 0.71 <0.001 PA Delay from the onset of the P wave on ECG to the onset of A wave on tissue Doppler, N: number, SD: Standard Deviation, LA: Left Atrium, RA: Right Atrium, RV: Right Ventricle
Tissue Doppler velocities for ruling out rejection in heart transplant recipients in the daily routine of the echocardiography laboratory: a feasibility study
Authors: Ruiz Ortiz M , Rodriguez Diego S , Delgado Ortega M , Esteban Martinez F , Rodriguez Almodovar A , Romo Penas E , Rodriguez Nieto J , Piserra Lopez-Fernandez De Heredia A , Perea Armijo J , Lopez Granados A , Lopez Aguilera J , Carrasco Avalos F , Arizon Del Prado JM , Pan Alvarez-Ossorio M , Mesa Rubio D
Published: February 2021

Funding Acknowledgements

Type of funding sources: None.

Background

The sum of systolic and early diastolic myocardial velocities at lateral mitral annulus, evaluated by tissue Doppler (in absolute values, s’+e’) in the apical four chambers view is a parameter whose value for ruling out acute cellular rejection (ACR) in heart transplant (HTx) recipients has been acknowledged by the European and Brazilian recommendations for the use of imaging in HTx. A recent study has shown its independent association with ACR in the context of classical and myocardial deformation variables, with a negative predictive value (NPV) of 98% for treatment requiring ACR (TR-ACR, grade ≥ 2R) for a cut-off point of ≥23 cm/s. This work was performed under experimental conditions (only one expert echocardiographer, only one high-end equipment).

Purpose

Our objective was to study the diagnostic utility of this parameter for ruling out rejection in HTx recipients in the daily routine of the echocardiography laboratory.

Methods

From October 2017 to May 2020, serial echocardiograms were performed to 33 consecutive HTx recipients, in the 3 hours after the routine surveillance endomyocardial biopsies (EMB), in the first year after HTx. Three sonographers, seven cardiology residents and six expert echocardiographers participated in the acquisition and interpretation of the images, with seven different echocardiographic machines in only one centre. We analysed the association of s’+e’ with the presence of ACR, and the NPV of s’+e’ ≥23 cm/s for ruling out TR-ACR was investigated.

Results

A total of 176 pairs of EMB and echocardiogram were obtained. The value of s’+e’ was significantly lower with higher severity of rejection: 25.6 ± 5.5 cm/s, 23.8 ± 5.1 cm/s and 21.6 ± 3.5 cm/s for ACR grade 0R (n = 91, 52%), 1R (n = 67, 38%) and ≥2R (n = 18, 10%), respectively, p = 0.005. It was also lower when comparing studies with (≥1R) and without rejection (23.4 ± 4.9 cm/s versus 25.6 ± 5.5 cm/s, p = 0.005), or TR-ACR versus the rest of series (21.6 ± 3.5 cm/s versus 24.8 ± 5.3 cm/s, p = 0.01). The area under curve for the detection of TR-ACR was 0.67 (CI95% 0.56-0.78), p = 0.02. A cut-off point of ≥23 cm/s, present in 57% of the studies, showed a NPV of 95% for TR-ACR.

Conclusion

Lateral mitral annulus velocities showed an excellent NPV of 95% for TR-ACR detection in HTx recipients when evaluated in the daily routine of an echocardiography laboratory with a wide variety of operators and echocardiographic equipment. This finding could be useful for reducing the number of EMB in selected cases.
Changes in diastology and atrial function in multimodality imaging after breast cancer radiotherapy - a six-year follow-up study
Authors: Vaarpu M , Lehmonen L , Kivisto S , Skytta T , Kellokumpu-Lehtinen P-L , Aula H , Raatikainen P , Virtanen V , Nikus K , Tuohinen S
Published: February 2021

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): State research funding (Finland) Heart Hospital funding (Tampere, Finland)

Aims

Breast cancer radiotherapy (RT) increases the incidence of heart failure with preserved ejection fraction with long latency. The prevalence and the early phases of this process are not well characterized. The aims of our study were to evaluate changes in diastology and left atrial function after breast cancer RT in a prospective manner.

Methods

31 patients with early stage left-sided breast cancer were studied prior to RT, immediately after RT and three and six years after RT. Biomarkers were measured and echocardiography, including left atrial strain, was performed at each visit. Cardiac magnetic resonance imaging (CMR) was performed at the six-year follow-up (FU).

Results

At baseline, the median diastology gradus was 1 with 5 patients displaying diastology gradus greater than 2. At six-year follow-up the median diastology gradus had increased to 2 (p = 0.012) with 13 patients in diastology gradus 3-4. Additionally, proBNP increased progressively from  baseline level of 63 [37, 124] ng/l to post-RT level of 84 [40, 154] ng/l (p = 0.031), to 90 [46, 132] ng/l at the three-year follow-up (p = 0.021) and to 98 [50, 176] ng/l at the six-year follow-up (p = 0.010). Left atrial strain initially increased from 23.2 ± 4.9% at baseline to 25.5 ± 6.7% post-RT (p = 0.199) and thereafter decreased to 21.2 ± 6.0% (p = 0.002) at six-year follow-up. There was no correlation in left atrial strain between 2D-echocardiography and CMR. Age (mean 62.2 years) had no correlation with changes in diastology or left atrial strain. Furthermore, left atrial strain rate (SR) increased progressively from 2.14 [1.83, 2.50]1/s at baseline to  2.35 [1.95, 2.96]1/s at the three-year follow-up (p = 0.040) and thereafter declined to 1.92 [1.62, 2.59]1/s (p = 0.014). The change in left atrial SR (from RT to the six-year control) was independently correlated with body mass index (BMI) (p = 0.044, β=0.472). The changes in diastology had no independent predictors.

Conclusions

RT induced a gradual worsening in diastology gradus, which was initially compensated with an increase in left atrial function. However, at the six-year follow-up, 43.7% of the patients had restrictive or pseudonormal diastology and a significant decline in left atrial strain and SR were detected. A lower BMI had a negative influence on the left atrial function.

Abstract Figure. Changes in diastoly during six-year FU
Global longitudinal strain at rest predicts significant coronary artery stenosis in patients with peripheral arterial disease
Authors: Ludovica Fiorillo LF , Ciro Santoro CS , Martina Scalise MS , Valentina Capone VC , Lucia La Mura LLM , Mario Enrico Canonico MEC , Teresa Fedele TF , Ofelia Casciano OC , Silvia Orefice SO , Federica Luciano FL , Vittoria Cuomo VC , Roberta Esposito RE
Published: February 2021

Funding Acknowledgements

Type of funding sources: None.

Background

Critical peripheral artery disease (PAD) is expression of systemic chronic atherosclerosis, it being often associated with  cardiovascular events. The assessment of global longitudinal strain (GLS) at rest by speckle tracking echocardiography could be useful to unmask significant coronary artery disease (CAD) in asymptomatic PAD patients.

Purpose

To determine whether resting GLS is able to predict significant coronary artery stenosis in PAD patients selected for peripheral or carotid angiography.

Methods

One-hundred three clinically relevant PAD patients (M/F = 76/27, age = 66.8 ± 10,2 years, 72 with significant  lower limb artery stenosis and 31 with carotid artery stenosis ≥50%), asymptomatic for CAD,  underwent standard echo-Doppler exam at rest, comprehensive of GLS analysis, prior peripheral and coronary angiography. Information on cardiovascular (CV) risk factors and comorbidities were collected. Patients with know CAD and previous myocardial infarction, left ventricular (LV) ejection fraction < 50% and inadequate echocardiographic imaging were excluded. According to the results of coronary angiography, patients were divided in two groups: with significant coronary artery stenosis (>50% of obstruction. n = 73) and without significant coronary artery lesions (n = 30).

Results

No intergroup difference in the prevalence of CV risk factors and comorbidities was found. Age, body mass index and blood pressure were comparable between the two groups. LV ejection fraction (59.9 ± 4.2% in patients with significant coronary stenosis vs. 60.2 ± 4.7% in those without coronary stenosis, p = 0.75) and wall motion score index (1.02 ± 0.09 vs 1.03 ± 0.09 respectively, p = 0.67) did not differ significantly. Conversely, GLS was lower in patients with significant coronary artery stenosis than in those without (21.6 ± 2.7% vs. 22.8 ± 2%, p < 0.02) (Figure 1). This difference remained significant comparing the carotid subgroup with coronary stenosis vs. those without (p < 0.05) whereas it did not achieve the statistical significance in patients with lower limb artery lesions (p = 0.42).

Conclusion

In PAD patients, GLS at rest shoes the capability in identifying patients at higher probability of significant coronary artery stenosis. This involves in particular patients with carotid artery stenosis. GLS might be helpful to select patients who need to extend the peripheral angiographic evaluation to the coronary tree.
Analysis of the left atrial function using two dimensional strain in patients with recent diagnosis of hereditary hemochromatosis
Authors: Saad AK , Aladio JM , Yamasato F , Volberg VI , Daruich J , Perez De La Hoz RA
Published: February 2021

Funding Acknowledgements

Type of funding sources: None.

Background. Hereditary hemochromatosis (HH) is a genetic condition associated with a systemic iron overload caused by a reduction in the concentration of the iron regulatory hormone hepcidin or the hepcidin-ferroportin complex activity.  Heart failure is the leading cause of death.  It has been demonstrated early stages of systolic and diastolic left ventricular dysfunction in previous studies. The main function of the left atrium (LA) is to modulate the left ventricular filling through the reservoir, conduct and bump phases.

Purpose. To compare the LA function between asymptomatic and recently diagnosed HH patients and a control group using two-dimensional speckle tracking.

Methods. In this prospective study, 30 patients with HH (90% males, 47 ± 18 years old)  and 30 healthy controls with a normal echo stress test (85% males, 45 ± 13 years old) were included. A conventional echocardiogram was performed. LA strain, LA strain rate and LA volumetric parameters during the reservoir, conduit and bump phases were studied according to the current recommendations. The LA stiffness index was calculated by using the ratio between E/e´ ratio and LA strain during the reservoir phase.

Results. LA volume was similar in both groups (36,5 ± 10 ml vs 32,3 ± 6,5 ml; p = 0.09). No differences were observed in LA ejection fraction (EF) (57.5 ± 10% vs 60 ± 5%; p = 0.32), LA passive EF (35 ± 12% vs 36 ± 9%; p = 0.82) or LA bump function (34 ± 11% vs 36 ± 9.9%; p = 0.41) between both groups. On the contrary, the HH group had lower LA reservoir strain (31.5 ± 6.5% vs 38.3 ± 7.9%; p = 0.002) and during the conduct phase (18 ± 7% vs 23.3 ± 6.4%; p = 0.01) than the control group. The LA stiffness index was significantly higher in the HH group (25.5 ± 9.1 vs 19.5 ± 6.4; p = 0.01).

Conclusion. Early abnormalities in the LA function could be detected by using two-dimensional speckle tracking study despite no evidence of changes in atrial size or volumetric parameters.

Abstract Figure.
LV twist predicts prognosis in children and adolescents with non-compaction cardiomyopathy
Authors: Piccinelli E , Sabatino J , Krupickova S , Fraisse A , Prota C , Bucciarelli V , Avesani M , Borrelli N , Delle Donne G , Josen M , Paredes J , Sirico D , Indolfi C , Daubeney P , Di Salvo G
Published: February 2021

Funding Acknowledgements

Type of funding sources: None.

Background

Left ventricular non-compaction cardiomyopathy (LVNC) is associated with poor clinical outcome in childhood, with heart failure, arrhythmias, and embolic events as main clinical manifestations. LV twist has recently been demonstrated having good predictive value in diagnosing LVNC in young patients. However, how LV twist may influence long-term clinical outcome of LVNC children and adolescents is still unknown.

The aim of this study was to analyse a set of echocardiographic parameters to find imaging predictors of worse clinical outcomes in a long-term follow-up of LVNC children and young patients.

Methods

Children and adolescents, followed from May 2012 to June 2020, were enrolled in a retrospective study. All patients underwent 2-dimensional speckle tracking echocardiography and cardiovascular magnetic resonance imaging (1.5 Tesla) at our Institution’s first evaluation.

Death, heart failure hospitalization, aborted sudden cardiac death, ventricular arrhythmias (sustained and non-sustained ventricular tachycardia), and embolisms (i.e. stroke, peripheral arterial embolism and/or pulmonary thromboembolism) were registered and referred to as major adverse cardiovascular events (MACEs).

Results

Recruited for the study were 47 children (mean age: 11.1± 5; age range: 0–18 years). Twenty-three patients fulfilled the cardiovascular magnetic resonance imaging diagnostic criteria for LVNC (LVNC group), while the remaining 24 did not and were included in the LV hypertrabeculation group (LVHT).

They were followed for 4.9 ± 1.0 years, and MACEs were registered. Thirteen children (56% of LVNC, 28% of total) had at least one MACE. Global longitudinal, circumferential and radial strains (GLS, GCS, GRS), LV twist and LVEF resulted being significantly reduced in children with MACEs at follow-up. A multivariable analysis was performed by combining four parameters: LV ejection fraction, GLS, GCS, LV twist. These independent variables were chosen according to univariable analyses and clinical relevance. The results from the analysis demonstrated that LV twist was the only independent predictor (P = 0.033, coeff. B 0.726) of worse clinical outcomes in young patients with LVNC.

Conclusions

LV twist is a promising tool to stratify and predict prognosis in LVNC young patients. Our findings show the importance of LV twist assessment to detect the severity of LVNC and to plan for early clinical intervention.
Mitral anular plane excursion predicts coronary stenosis during stress echocardiography with dipyridamole
Authors: Moderato L , Binno S , Rusticali G , Dallospedale C , Aschieri D , Pastorini G , Piepoli MF
Published: February 2021

Funding Acknowledgements

Type of funding sources: None.

Background

Dipyridamole stress echocardiography (DSE) is an important tool for detecting reversible ischemia in patients with suspected coronary artery disease (CAD); nonetheless, the results of the test are related to wall motion abnormalities, moderately operator-dependent, and left anterior descending (LAD) artery reserve, resulting in a moderate sensibility and specificity. 

Purpose

Aim Of our study was to evaluate whether an easy-to-use parameter like mitral annular plane systolic excursion (MAPSE) could be useful to identify CAD during DSE. 

Methods

We prospectively enrolled 512 patients that underwent DSE for suspected CAD; rest and peak MAPSE was acquired; 148 patients were referred to perform coronary angiography, with evidence of severe coronary stenosis in 91 patients.  

The mean age was 66.7 ±11 years, male gender was prevalent (64%). 

MAPSE at the peak was significantly different between patients with CAD and patient without (13,4mm vs 16,81 mm , p < 0.001); in fact, patients with CAD showed a blunted or no increase of MAPSE after dipyridamole infusion, with a significative difference in Delta Mapse (Mapse peak-Mapse rest) between groups ( -0.5mm vs 2.8mm) By using a Receiver Operating Curve, the Area under the curve was 0,764 (0.682-0.846), with the best cut-off value of +0.5mm (Sensibility 77%, Specificity 62% - Figure 1), comparabale with traditional methods like LAD reserve, FE reduction or Wall Motion Score Index. 

Discussion

to our knowledge, this is the first study that compared the behavior of MAPSE during dipyridamole infusion in patients with and without coronary artery disease. MAPSE is a well-known surrogate of longitudinal systolic function and has increased sensitivity over traditional methods of systolic performance such as LV-EF: in this context, dipyridamole induced reversible ischemia could affect prematurely MAPSE then EF or wall motion abnormalities.

In our study, in patients with evidence of reversible ischemia during DSE, a blunted or no increase of MAPSE was able to predict CAD. Incorporating this easy-to-use parameter could improve the specificity of DSE and strengthen the suspect of reversible ischemia when clear wall motion abnormalities are not found.

Abstract Figure. Mean value of Mapse and ROC curve
Role of T1 mapping in identification of convalescent Takotsubo cardiomyopathy
Authors: Mathai S , Sehmi J , Auger D , L" Heureux C , Keenan NG
Published: February 2021

Funding Acknowledgements

Type of funding sources: None.

Background

Takotsubo cardiomyopathy remains an elusive entity to diagnose, especially with increasing time following the initial clinical event. Patients are often referred for cardiac MR, but when performed on a convalescent patient, the conventional CMR exam can be normal. However CMR elevated native T1 values on mapping may persist, aiding diagnosis.

Purpose

We sought to review a series of confirmed Takotsubo cases to evaluate which CMR features were most helpful in making a diagnosis.

Methods

We reviewed 2 years of CMR exams in our institution and identified 14 patients with a confirmed diagnosis of Takotsubo cardiomyopathy after a read of all clinical data by two consultant cardiologists. All of the 14 patients had a troponin positive cardiac event, unobstructed coronary arteries on invasive angiography and echocardiographic evidence of apical hypo/akinesia (or basal, in the non-apical variants) at the time of presentation. All CMR exams were performed at 1.5T. All included functional assessment, T1 mapping and late gadolinium enhancement(LGE). Some exams also included T2 mapping and STIR.

Results

All patients were female. The time interval between presentation and CMR exam varied from 24 hours to 2 years. 2 of the scans showed evidence of non-apical Takotsubo cardiomyopathy. At the time of CMR, only 7 patients(50%) had a residual regional wall motion abnormality, but 13 patients(93%) had a region of elevated native T1 (>1 myocardial segment). High signal was identified on STIR in 6(43%) and elevated native T2 in 10(71%). Of interest, we identified small areas of patchy LGE in 2 patients(14%).

Conclusion

Increased native T1 signal may be the only residual cardiac MRI marker of previous Takotsubo cardiomyopathy, persisting for months after the initial cardiac event, even after resolution of regional wall motion abnormalities and recovery of the left ventricular function. T1 mapping should be performed in CMR exams for Takotsubo cardiomyopathy to improve diagnostic yield.

Abstract Figure. CMR in convalescent Takotsubo