Block Failure Research Articles

Right bundle branch block and heart failure: When cardiac resynchronization therapy is effective

A 70-year-old man with ischemic cardiomyopathy (left ventricular ejection fraction 20%), right bundle branch block (RBBB), and prolonged qLV (Figure 1A) received cardiac resynchronization therapy (CRT).

Sacralization of Coccygeal Vertebra: A Descriptive Observational Study in Bangladesh

Background: In the sacrococcygeal region, anatomical variation is due to the sacralization of the coccygeal vertebra, which is the due union of/fusion of the fifth sacral with the first coccygeal vertebra of five couples of sacral foramina under-detected or asymptomatic beyond radiological assessment. That is why it is challenging to know the cause of coccydynia, caudal block failure, the difficult second stage of labor, and perineal tears. The present study aims to improve knowledge about the anatomical variation of sacralization of the coccygeal vertebra. Additionally, to find the prevalence of sacralization of coccygeal vertebra in Sylhet, Bangladesh.Methods: This study was performed on 60 parched, totally calcified, typical sacra of mature-age individuals of undetermined sexes, fulfilling the inclusion criteria from the bone bank of the osteology museum of the Department of Anatomy, Sylhet MAG Osmani Medical College, Sylhet, Bangladesh, from July 2017 to June 2018. Sex determination of the collected unknown sacra was conducted using discriminant function analysis. It was found that 50% (30) were male and 50% (30%) were female. The unpaired t-tests and chi-square were utilized to determine the statistical significance.Results: Out of 60 sacra, eight (13.33%) samples presented with sacralization. This study found that males had significantly higher straight (p=0.05) and curved (p=0.05) lengths of sacrococcygeal vertebrae. The sacrococcygeal curvature index (SCI) showed statistically significant (p=0.05) differences between the sexes.Conclusion: Sacralization may exert an impact on the caudal block. It could extend the second stage of the labor process with perineal tears. Therefore, knowledge about the anatomical variation of the coccygeal vertebra is essential.

Experimental research on damage identification of topping dangerous rock structural surface based on dynamic characteristic parameters

Rock block tilting is one of the most common types of dangerous rock block failures with no clear indicator of displacement prior to failure. Existing stability evaluation methods remain limited in their ability to constrain the non-penetrating section area, which is closely related to rock stability, and stability evaluations are therefore associated with large uncertainties. The dynamic characteristic parameters of toppling dangerous rock are closely related to structural plane strength. Under vibration loading, rainfall, and/or excavation unloading conditions, the structural plane becomes damaged and the dynamic characteristic parameters change. In this study, we present a dynamic characteristic model of rock tilting and identify the quantitative and qualitative relationship between dynamic characteristic parameters and the bonded area of the structural plane. The model accuracy is verified by experiments. The experimental results show that the damping ratio decreases linearly with structural plane damage, whereas the maximum vibration speed and particle trajectory increases nonlinearly and the natural vibration frequency decreases nonlinearly. The dynamic characteristic model and experimental results can be used to evaluate the degree of structural surface damage of toppling dangerous rock.

Geotechnical Measurements for the Investigation and Assessment of Arctic Coastal Erosion—A Review and Outlook

Geotechnical data are increasingly utilized to aid investigations of coastal erosion and the development of coastal morphological models; however, measurement techniques are still challenged by environmental conditions and accessibility in coastal areas, and particularly, by nearshore conditions. These challenges are exacerbated for Arctic coastal environments. This article reviews existing and emerging data collection methods in the context of geotechnical investigations of Arctic coastal erosion and nearshore change. Specifically, the use of cone penetration testing (CPT), which can provide key data for the mapping of soil and ice layers as well as for the assessment of slope and block failures, and the use of free-fall penetrometers (FFPs) for rapid mapping of seabed surface conditions, are discussed. Because of limitations in the spatial coverage and number of available in situ point measurements by penetrometers, data fusion with geophysical and remotely sensed data is considered. Offshore and nearshore, the combination of acoustic surveying with geotechnical testing can optimize large-scale seabed characterization, while onshore most recent developments in satellite-based and unmanned-aerial-vehicle-based data collection offer new opportunities to enhance spatial coverage and collect information on bathymetry and topography, amongst others. Emphasis is given to easily deployable and rugged techniques and strategies that can offer near-term opportunities to fill current gaps in data availability. This review suggests that data fusion of geotechnical in situ testing, using CPT to provide soil information at deeper depths and even in the presence of ice and using FFPs to offer rapid and large-coverage geotechnical testing of surface sediments (i.e., in the upper tens of centimeters to meters of sediment depth), combined with acoustic seabed surveying and emerging remote sensing tools, has the potential to provide essential data to improve the prediction of Arctic coastal erosion, particularly where climate-driven changes in soil conditions may bias the use of historic observations of erosion for future prediction.

Forecast of violation of soil stability according to the parameters of pulsed electromagnetic fields of the VLF range

The relevance of the task of monitoring and forecasting exogenous processes is determined by the widespread occurrence of landslides, including in many territories of the Russian Federation. Catastrophic slope failure is one of the most common natural hazards, resulting in both human casualties and economic damage. The aim of the study is to test the algorithms for assessing the stress-strain state of rocks using the parameters of the natural pulsed electromagnetic field of the Earth (ENEMF) on an active landslide that threatens the infrastructure of Tomsk. The paper shows that the precursors of the activation of geodynamic slope processes are fixed long before changes in the relief caused by the failure of rock blocks. The conducted studies have shown the high promise of the ENPEMF method for forecasting extreme events that pose challenges for the territory.

A double-phase field model for multiple failures in composites

Fiber reinforced composites have very excellent mechanical properties due to their sophistic microstructures. At the same time these microstructures can induce complex failure mechanisms including intralaminar damage, interlaminar damage and the interactions between them. Nevertheless, high fidelity simulations for these complex failure mechanisms are still challenging. In this paper, we develop a double-phase field model for complex failure in fiber reinforced composite. In the model, two different phase fields, i.e., fiber phase field and matrix phase field, are adopted for characterizing fiber damage and matrix damage, respectively. The failure mechanisms of fiber damage as well as the other modes in matrix damage are identified through a new strain energy density form that contains four different effective strain variables as well as a new effective constitutive tensor. Then by coupling with redefined degradation functions corresponding to different failure mechanisms, specified damage initiation and evolution criteria can be embedded into the proposed model automatically. Moreover, the new model is implemented in an explicit manner. The proposed model is verified and validated through the comparison between the predicted results and that of the experiments on the failure in unidirectional block and composite laminate.

Deep subdomain generalisation network for health monitoring of high-speed train brake pads

Uneven wear at different locations in high-speed train brake pads creates inconsistent vibrations, which make the criteria learned by the intelligent model hard to standardise to determine friction block failure. Variable friction-induced vibration makes brake pad health monitoring a cross-domain diagnostic problem. This study proposes a deep subdomain generalisation network for online monitoring of the health status of train brake pads. In contrast to existing transfer learning methods, the proposed approach does not assume the availability of test data during training. The model is generalised using unsupervised learning to new scenarios with unknown specific locations of uneven wear. The network reduces the discrepancy explicitly among the distributions of relevant source subdomains using local maximum mean discrepancy, which helps subdomains with identical labels more accurately find an appropriate common subspace. Furthermore, Bayesian optimisation is used to unify feature extraction, domain generalisation and hyper-parameter optimisation into a framework. The vibration–acceleration signals of different friction blocks are collected, and generalisation experiments are performed on both braking-friction and rotating-machinery datasets. The results indicate that the proposed model outperforms the other domain generalisation approaches and accurately identifies the state of a target friction block.

Short QRS Duration After His-Purkinje Conduction System Pacing Predicts Left Ventricular Complete Reverse Remodeling in Patients With True Left Bundle Branch Block and Heart Failure.

ObjectiveThis study aimed to explore the outcomes of His-Purkinje conduction system pacing (HPCSP) and to screen the predictors of left ventricular (LV) complete reverse remodeling in patients with true left bundle branch block (LBBB) and heart failure with reduced ejection fraction (HFrEF).MethodsPatients who underwent HPCSP for true LBBB and HFrEF from April 2018 to August 2020 were consecutively enrolled. All participants were followed up for at least 1 year. Thrombosis, infection, lead dislodgement, perforation, and other complications were observed after HPCSP. Clinical data, including echocardiographic parameters, electrocardiogram measurements, and cardiac function, were assessed before and after the procedure.ResultsA total of 46 patients were enrolled. HPCSP was successfully deployed in 42 cases (91.30%), which included 37 cases with His bundle pacing (HBP) and 5 cases with left bundle branch pacing (LBBP). The QRS duration decreased significantly (169.88 ± 19.17 ms vs. 113.67 ± 20.68 ms, P < 0.001). Left ventricular end-systolic volume (LVESV) (167.67 ± 73.20 ml vs. 85.97 ± 62.24 ml, P < 0.001), left ventricular end-diastolic diameter (LVEDD) (63.57 ± 8.19 mm vs. 55.46 ± 9.63 mm, P = 0.003) and left ventricular ejection fraction (LVEF) (26.52 ± 5.60% vs. 41.86 ± 11.56%, P < 0.001) improved dramatically. Complete reverse remodeling of the LV with normalized LVEF and LVEDD was found in nearly half of the patients (45.24%). A short QRS duration after HPCSP was a strong predictor of normalized LVEF and LVEDD (P < 0.001). The thresholds increased markedly in two patients approximately 6 months after HBP. No patients died during the total follow-up period of 20.07 ± 6.45 months.ConclusionComplete reverse remodeling of the LV could be found in nearly half of the patients with HFrEF and true LBBB after HPCSP, and the short QRS duration after HPCSP was a strong predictor.

HF-564-01 READMISSION OUTCOMES IN PATIENTS WITH CARDIAC SARCOIDOSIS

Sarcoidosis is a multi-system disorder which can affect the lungs, lymph nodes, liver, spleen, skin, nervous system and the heart. Cardiac sarcoidosis (CS) has historically been under-diagnosed but continues to be associated with significant morbidity and mortality. The most common presenting symptoms include advanced atrioventricular block, ventricular tachycardia (VT) and heart failure (HF).

CE-522-04 MORTALITY AND MORBIDITY OF CARDIAC SARCOIDOSIS: AN INTERNATIONAL REGISTRY

Sarcoidosis is a rare disease that can affect the heart and can cause ventricular tachyarrhythmias, AV block or heart failure. Patients with cardiac involvement may have shortened lifespans. Cardiac factors impacting outcomes have not been systematically analyzed.

PO-643-06 EVALUATION OF ELECTROCARDIOGRAPHIC AND INTRACARDIAC ELECTROGRAM CHARACTERISTICS FOR RESPONSE TO HIS-PURKINJE CONDUCTION SYSTEM PACING IN PATIENTS WITH LEFT BUNDLE BRANCH BLOCK CORRECTED BY HIS BUNDLE PACING

His-Purkinje conduction system pacing (HPCSP) has been proved to improve clinical outcomes in patients with left bundle branch block (LBBB) and heart failure. However, some patients still remain non-responsive to HPCSP.

Case Report: Importance of MRI Examination in the Diagnosis and Evaluation of COVID-19 mRNA Vaccination Induced Myocarditis: Our Experience and Literature Review

Acute myocarditis is a rare but serious complication associated with mRNA-based coronavirus disease 2019 (COVID-19) vaccination. In this article, four COVID-19 mRNA vaccination induced myocarditis cases managed at our tertiary Medical Center have been discussed. Three patients had typical myocarditis. One patient suffered from atrioventricular block and heart failure, which required more intensive treatment, but eventually improved. Additionally, a review of cardiac magnetic resonance imaging (MRI) features related to the diagnosis of myocarditis showed that COVID-19 mRNA vaccine-associated myocarditis tend to have more late-gadolinium enhancement (LGE) accumulation in the inferior lateral wall direction. According to a report by the U.S. Centers for Disease Control and Prevention (CDC), the diagnosis of COVID-19 mRNA vaccine-associated myocarditis is based on clinical symptoms, altered myocardial enzymes, cardiac MRI finding, or histopathology. Cardiac MRI is relatively less invasive than myocardial biopsy and plays an important role in the diagnosis of myocarditis. This review may aid in the diagnosis of COVID-19 mRNA vaccine-associated myocarditis.

Ultrasound-guided caudal blockade and sedation for paediatric surgery: a retrospective cohort study.

SummaryData on safety and success rates of ultrasound‐guided caudal blockade, performed on sedated children with an uninstrumented airway, are scarce. We performed a retrospective observational study of validated data from April 2014 to December 2020 in a paediatric cohort where the initial plan for anaesthetic management was sedation and caudal epidural without general anaesthesia or airway instrumentation. We examined success rates of this approach and rates of block failure and block‐related complications. In total, 2547 patients ≤ 15 years of chronological age met inclusion criteria. Among the 2547 cases, including 453 (17.8%) former preterm patients, caudal‐plus‐sedation success rate was 95.1%. The primary anaesthesia plan was abandoned for general anaesthesia in 124 cases. Pain‐related block failure in 83 (3.2%) was the most common cause for conversion. Complications included 39 respiratory events and 9 accidental spinal anaesthetics. Higher odds of pain‐related block failure were associated with higher body weight (adjusted OR 1.063, 95%CI 1.035–1.092, p < 0.001) as well as with mid‐abdominal surgery (e.g. umbilical hernia repair) (adjusted OR 15.11, 95%CI 7.69–29.7, p < 0.001), whereas extreme (< 28 weeks) former prematurity, regardless of chronological age, was associated with higher odds (adjusted OR 3.62, 95%CI 1.38–9.5, p = 0.009) for respiratory problems. Ultrasound‐guided caudal epidural, performed under sedation with an uninstrumented airway, is an effective technique in the daily clinical routine. Higher body weight and mid‐abdominal surgical procedures are risk factors for pain‐related block failure. Patients who, regardless of chronological age, had been born as extreme preterm babies are at the highest risk for respiratory events.

Modeling ice block failure within drift ice and ice rubble.

A major challenge within material science is the proper modeling of force transmission through fragmenting materials under compression. A particularly demanding material is sea ice, which on small scales is an anisotropic material with quasibrittle characteristics under failure. Here we use the particle-based model HiDEM and laboratory-scale experiments on saline ice to develop a material model for fragmenting ice. The material behavior of the HiDEM model-ice, and the experiments are compatible on force transmission and fragmentation if: (i) the typical HiDEM glacier-scale particle size of meters is brought down to millimeters corresponding to the grain size of the laboratory ice, (ii) the often used HiDEM lattice structure is replaced by a planar random structure with an anisotropy in the direction normal to the randomized plane, and (iii) the instant tensile and bending failure criterion, used in HiDEM on glacier scale, is replaced by a cohesive softening failure potential for energy dissipation. The main outcomes of this exercise is that many of the, more or less, traditional ice modeling schemes are proven to be incomplete. In particular, local crushing of ice is not valid as a generic failure mode for fragmented ice under compression. Rather, shear failure, as described by Mohr-Coulomb theory is demonstrated to be the dominant failure mode.

This Month in Anesthesiology

This Month in Anesthesiology

Anesthesiology

The dural puncture epidural technique may improve analgesia quality by confirming midline placement and increasing intrathecal translocation of epidural medications. This would be advantageous in obese parturients with increased risk of block failure. In this issue of Anesthesiology, Tan et al. test the hypothesis that quality of labor analgesia will be improved with dural puncture epidural compared to standard epidural technique in obese parturients. In an accompanying editorial, Segal and Pan describe the evolution of the dural puncture epidural technique and conclude that the overall impact of this technique on the quality of labor analgesia is modest at best. Cover Illustration: A. Johnson, Vivo Visuals Studio.

Autoclaved aerated concrete (AAC) shear and tensile bond strengths with various mortar formulations and thicknesses.

For masonry walls, autoclaved aerated concrete (AAC) blocks are widely utilised. Compression and tension bonding must constantly be calculated for various mortar mixtures to evaluate the strengths of the AAC block-mortar contact a mortar with a polymer modification and conventional cement sand mortar (1:5 or 1:7) with a thickness of 12mm, 17mm, or 22mm are examined for binding strength on an AAC block mortar interface. Before pouring the cement sand mortar into the brickworks, On the block surface, a thin cement slurry covering was placed. A three-fold analysis was used to estimate the shear bond strength for all types of interfaces, while a cross-couples test was used to evaluate the tensile bond strength.The modified polymer mortar (PMM) had a shear bond strength of 0.15 MPa, with block failure of the vigorous failure type, whereas the cement sand mortar had the greatest shear bond strength of 0.14 MPa, with a cement-sand mortar ratio of 1:5 and a thickness of 17 mm. Since the tensile bond strength of all test specimens utilised in this study was evaluated, PMM had the greatest tensile bond strength of 0.22 MPa. Based on observed failure patterns and the strength of the tensile and shear bond of AAC mats, a 1:5 ratio cement sand or modified polymer mortar with a thickness of 17 mm can be selected from all possibilities for AAC brickwork.

The role of occipital nerve block with ultrasound guidance in occipital neuralgia cases

Introduction. Occipital neuralgia (ON) is a well-known cause of headache that affecting the posterior head at the occipital nerve(s) distribution. It is a multiple-factor clinical condition resulting from the pathology of the greater, lesser or third occipital nerve. Interventional therapy, such as occipital nerve block (ONB), is one of the various modalities that could be normally considered when the conservative wasn’t satisfying. Besides as effective treatment, ONB also used as an important diagnostic procedure for occipital neuralgia. Content. Currently, there is no a complete consensus among practitioners regarding the optimal therapy for occipital neuralgia although many modalities offered. ONB traditionally performed with blinded approach relying on anatomic landmarks create the higher risks of injection in the occipital artery and/or block failure. Therefore, ONB with ultrasound guidance becomes solution to improve the safety and efficacy of therapy especially in occipital neuralgia cases. Conclusion. Occipital nerve block with ultrasound guidance is recommended as primary interventional therapy for occipital neuralgia cases.

Mechanism of the effects of sodium channel blockade on the arrhythmogenic substrate of Brugada syndrome.

The mechanisms by which sodium channel blockade and high-rate pacing modify electrogram (EGM) substrates of Brugada syndrome (BrS) have not been elucidated. The purpose of this study was to determine the effect of ajmaline and high pacing rate on the BrS substrates. Thirty-two patients with BrS (mean age 40 ± 12 years) and frequent ventricular fibrillation episodes underwent right ventricular outflow tract substrate electroanatomical and electrocardiographic imaging (ECGI) mapping before and after ajmaline administration and during high-rate atrial pacing. In 4 patients, epicardial mapping was performed using open thoracotomy with targeted biopsies. Ajmaline increased the activation time delay in the substrate (33%; P = .002), ST-segment elevation in the right precordial leads (74%; P < .0001), and the area of delayed activation (170%; P < .0001), coinciding with the increased substrate size (75%; P < .0001). High atrial pacing rate increased the abnormal EGM duration at the right ventricular outflow tract areas from 112 ± 48 to 143 ± 66 ms (P = .003) and produced intermittent conduction block and/or excitation failure at the substrate sites, especially after ajmaline administration. Biopsies from the 4 patients with thoracotomy showed epicardial fibrosis where EGMs were normal at baseline but became fractionated after ajmaline administration. In some areas, local activation was absent and unipolar EGMs had a monophasic morphology resembling the shape of the action potential. Sodium current reduction with ajmaline severely compromises impulse conduction at the BrS fibrotic substrates by producing fractionated EGMs, conduction block, or excitation failure, leading to the Brugada ECG pattern and favoring ventricular fibrillation genesis.

Component Damage and Failure Sequence of Track-bridge System for High-speed Railway under Seismic Action

ABSTRACT Evaluation of the damage and failure sequence of key components of track-bridge system for high-speed railway under seismic action is the basis for the design of a high-speed railway system and function recovery after earthquake. However, this evaluation has not been studied well. In this study, a simply supported beam with CRTS II track system and CRH2 high-speed train were taken as research objects. A train-bridge coupled finite element model was established, and experimental verification was carried out. Ten seismic waves exhibiting the highest matching degree with the site characteristics of bridge site were selected, and a nonlinear time-history analysis was carried out. The average peak ground acceleration (PGA) was obtained when each component suffered damage and failure for the first time, and the damage and failure sequences of components were arranged to analyze the seismic damage mode and failure mechanism of track-bridge system for high-speed railway. Finally, the corresponding damage and failure levels for track-bridge system were established. According to the research findings, under longitudinal earthquake, the damage and failure sequence of components is in the order of damage and failure of abutment sliding layer, damage of fixed abutment bearing, damage and failure of shear slot, failure of fixed abutment bearing, damage and failure of fixed pier bearing, and damage and failure of pier. Under transverse earthquake, the damage failure sequence of components is in the order of damage of abutment sliding layer, damage and failure of fixed pier bearing, damage of abutment sliding layer, damage of abutment fixed bearing, damage and failure of block, failure of fixed abutment bearing, and damage and failure of shear slot and pier. The fastener, mortar layer, and shear rebar remain in an intact state under transverse and longitudinal seismic motions. The dynamic effect of trains has no significant effect on the damage mode of track-bridge system for high-speed railway and yield order of key components.