Conduction System Research Articles

Charge Transfer Plasmons Enabled by Supramolecular Plug: From Optoelectronic Switching to Enhanced Chiral Sensing.

Miniaturization and integration of plasmonic nanodevices are fundamentally limited by quantum tunneling, which leads to quantum plasmonics with reduced local E-field intensity. Despite significant efforts devoted to modeling and deterring the detrimental effect of quantum plasmonics, the modulation and application of electron transport through the subnanometer gaps seems rarely exploited due to the limited tunability of conventional quantum materials. Here, we establish a supramolecular plasmonic system made of pillar[5]arene complexes and plasmonic resonators (nanoparticle-on-mirror, NPoM). The supramolecular assemblies significantly enhance the gap conductance of NPoM, which results in a blue-shift of the coupled plasmons. Plasmonic hot-electron transport with laser excitation further modulates the gap plasmons, which are fully reversible and beneficial for enhanced chiroptic sensing. Such a conductive supramolecular plasmonic system not only suggests an optoelectronic switching strategy for charge transfer plasmons but also provides a superior sensing platform for single molecules.

Structural basis and molecular mechanisms of Cl- transmembrane transport in cardiomyocytes

The intracellular concentration of chlorine anions ([Cl-]i), the equilibrium potential for chlorine anions (ECl) and transmembrane chloride currents (ICl) are the factors that significantly influence the electrophysiological properties of excitable tissue, including the myocardium. Several types of chloride (anion) conductance have been identified in the heart. In recent years, a number of transmembrane proteins demonstrating chloride conductance have been identified (CFTR, ClC, TMEM16, LRRC8), and the expression of these macromolecules in cardiac tissue has been confirmed. Accumulated data allow for establishing a molecular substrate for some chloride anion currents (ICl,PKA, ICl,ir, ICl,vol, ICl,swell, ICl,Ca, Ito2) detected in the heart. Furthermore, the molecular mechanisms regulating [Cl-]i and ECl through chloride cotransporters (KCC, NKCC1) and chloride-bicarbonate exchangers have been established. The variety of structures determining chloride transmembrane conductivity and the complexity of molecular mechanisms regulating chloride homeostasis underlie the complex effects of activation of chloride transporters in the pacemaker, conduction system and working myocardium of the heart. This review discusses the structural, biophysical properties and molecular regulation of chloride transporter protein complexes identified in the myocardium. The review also covers the mechanisms by which chloride transmembrane transport influences the bioelectrical activity of cardiomyocytes.

A Direct Current Self-Sustained Moisture-Electric Generator with 1D/2D Hierarchical Nanostructure for Continuous Operation of Off-Grid Electronics.

Ubiquitous moisture is a colossal reservoir of clean energy, and the emergence of moisture-electric generators (MEGs) is expected to provide direct power support for off-grid electronic devices anytime and anywhere. However, most MEGs rely on auxiliary energy storage devices and rectifier circuits to drive small electronic devices, which hinder scalability and widespread deployment, and the development of direct current (DC) MEGs with high power output that can directly drive off-grid electronic devices is highly promising but challenging. Herein, a self-sustained moisture-electric generator (SMEG) with a hierarchical nanostructure based on one-dimensional (1D) negatively charged nanofibers and two-dimensional (2D) conductive nanosheets was demonstrated to generate continuous DC electricity from atmospheric humidity. Sulfation of bacterial cellulose nanofibers lowers the surface potential and increases the surface charge energy, and reduced graphene oxide (rGO) provides a conduction pathway for electrons. The hierarchical nanostructures constructed by the combination of 1D nanofibers and 2D nanosheets endow the SMEG with self-sustained moisture gradients and structural anisotropy, which force the generation of a pseudocurrent. This combination also constructs microcapacitors that further enhance the moisture-electric power output. The SMEG can generate a continuous voltage in excess of 0.54 V for over 2160 h, with a power density of about 822 μW cm-3, demonstrating excellent operational durability. This research provides a feasible solution for the development of sustainable, versatile, and efficient power supplies for off-grid self-powered devices.

The G4 resolvase Dhx36 modulates cardiomyocyte differentiation and ventricular conduction system development.

Extensive genetic studies have elucidated cardiomyocyte differentiation and associated gene networks using single-cell RNA-seq, yet the intricate transcriptional mechanisms governing cardiac conduction system (CCS) development and working cardiomyocyte differentiation remain largely unexplored. Here we show that mice deleted for Dhx36 (encoding the Dhx36 helicase) in the embryonic or neonatal heart develop overt dilated cardiomyopathy, surface ECG alterations related to cardiac impulse propagation, and (in the embryonic heart) a lack of a ventricular conduction system (VCS). Heart snRNA-seq and snATAC-seq reveal the role of Dhx36 in CCS development and in the differentiation of working cardiomyocytes. Dhx36 deficiency directly influences cardiomyocyte gene networks by disrupting the resolution of promoter G-quadruplexes in key cardiac genes, impacting cardiomyocyte differentiation and CCS morphogenesis, and ultimately leading to dilated cardiomyopathy and atrioventricular block. These findings further identify crucial genes and pathways that regulate the development and function of the VCS/Purkinje fiber (PF) network.

Maternal hypertensive disorders of pregnancy and electrocardiographic findings among newborns: The Copenhagen Baby Heart Study.

Maternal preeclampsia is associated with both congenital heart defects and changes in left ventricular structure and function in the offspring. Whether preeclampsia and gestational hypertension also affect the offspring's cardiac conduction system is unknown. This study assesses whether infants exposed to maternal hypertensive disorders of pregnancy (HDPs) exhibit changes in their electrocardiogram (ECG) compared with infants unexposed to HDPs. This population-based cohort study included newborns from the Copenhagen Baby Heart Study who had an ECG performed within 30 days of birth and had available obstetric information. ECG parameters of newborns exposed to maternal HDPs were compared with those of unexposed newborns using linear regression. Our study cohort included 11,826 newborns, including 441 exposed to maternal preeclampsia and 320 exposed to gestational hypertension. Infants exposed to preeclampsia had prolonged QRS durations (adjusted mean difference 0.6 ms, 95% confidence interval [CI] 0.04, 1.16) and lower maximum amplitudes of the R-wave in V1 (adjusted mean difference, linear scale 0.95, 95% CI 0.90, 1.00), compared with unexposed infants. Exposure to maternal preeclampsia was not associated with changes in other ECG parameters. Exposure to gestational hypertension was associated with increased QT interval durations (QTc Bazett, adjusted mean difference 2.48 ms, 95% CI -0.23, 5.20; QTc Fridericia, adjusted mean difference 2.32 ms, 95% CI -0.19, 4.83). Our findings suggest that the newborn cardiac conduction system is affected by exposure to maternal preeclampsia. This could reflect the previously described thickening of the left ventricular myocardium in infants exposed to preeclampsia.

Cardiac resynchronization therapy guided by interventricular conduction delay: How to choose between biventricular pacing or conduction system pacing.

Biventricular pacing (BIV) is the gold standard for cardiac resynchronization therapy (CRT). Thirty percent of patients do not respond to CRT. Conduction system pacing (CSP) represents a viable alternative. Interventricular conduction delay (IVCD), as electrical desynchrony marker, is a CRT response predictor. The aim of this study was to determine the incidence of CRT responders by selecting the best approach between BIV and CPS based on intraoperative IVCD measurement in patients with HFrEF and LBBB. Ninety-six patients were randomly assigned in a 1:1 ratio to either a standard BIV group(control group, CG) or a group where the CRT approach was determined based on IVCD evaluation(study group, SG). If the right ventricular sensed electrogram (RVs)-left ventricular sensed electrogram (LVs) interval was ≥100 ms, the lead was left in its original position; otherwise, the LV lead was removed, and CSP was performed instead. Clinical, EKG, and echocardiographic features have been assessed pre- and 6 months post-implant. Echocardiographic and clinical responder were evaluated. Thirty-seven percent of patients in the SG underwent CSP, as the operative algorithm. The incidence of CRT responders was significantly higher in the SG (echocardiographic criterion: 92.5% vs. 69.8%, p:.009; clinical criterion 87.5% vs. 62.8%, p:.014). The SG showed a significantly greater difference in EF between pre- and post-implant as well as reduced end-diastolic and systolic volumes. Univariate and multivariate regression analysis indicated that enrollment in the SG was the only factor associated with CRT response. Intraoperative assessment of IVCD could help determine the optimal CRT approach between BIV and CSP, leading to a significant improvement in the rate of CRT responders.

Comparing the effects of three local anaesthetic agents on cardiac conduction system - A randomised study.

This study aimed to compare the effects of three local anaesthetic (LA) agents, namely bupivacaine, levobupivacaine, and ropivacaine, on the cardiac conduction system as assessed by corrected QT (QTc) and P wave dispersion (PWD) intervals in lower limb orthopaedic surgeries and to find the most suitable LA agent that can be used for a long duration. The study included 75 patients with American Society of Anesthesiologists physical status I and II of either gender in the age group of 18-65 years undergoing elective lower limb orthopaedic surgeries under epidural anaesthesia. These were allocated to groups B (bupivacaine), L (levobupivacaine), and R (ropivacaine). We observed blood pressure, heart rate, respiratory rate, PWD, and QTc intervals from baseline value through Holter monitoring, pain assessment by visual analogue scale, and demand and total volume of LA consumed by patient-controlled analgesia devices. The repeated measures of ANOVA were carried out to find the effect of time and time-to-group interaction among the groups across the periods. On intergroup comparison of QTc and PWD, no significant difference among groups was observed, but on intragroup analysis, a statistically significant increase in QTc and PWD from baseline was observed for each of groups B, L, and R at all time intervals. However, the mean increase in QTc and PWD recorded for Group B was higher than in groups L and R. Bupivacaine has the maximal tendency to prolong QTc and PWD. All three agents showed comparable haemodynamic effects and time to onset of sensory and motor blockade.

Aligned Ion Conduction Pathway of Polyrotaxane-Based Electrolyte with Dispersed Hydrophobic Chains for Solid-State Lithium–Oxygen Batteries

HighlightsStrategic materials design of polyrotaxane-based electrolytes was suggested by aligning the ion conduction pathways and dispersing hydrophobic chains for solid-state Li–O2 batteries.Owing to intentional design, solid-state Li–O2 battery resulted in stable potential over 300 cycles at 25 °C.

Synergetic integration of photothermal and self-cleaning features in a composite phase change material based on layered double hydroxides and polypyrrole

Composite phase change materials (PCMs) with photothermal functionality play a crucial role in efficiently storing and utilizing solar energy. However, the challenge of effectively removing of contaminants on photothermal conversion coatings has long puzzled researchers. In this study, we propose a novel approach to enhancing both photothermal conversion performance and self-cleaning properties of wood-based composite phase change materials, ultimately facilitating the sustainable and effective utilization of solar energy. The method utilized metal-organic frameworks (MOFs) as a precursor to form rough layered double hydroxides (LDH) on the wood surface through hydrolysis-induced exchange. Subsequently, polypyrrole (PPy) was deposited through vapor phase onto the LDH, and paraffin wax (PW) is utilized as the phase change material to prepare a novel composite phase change material. This modified wood structure facilitates leak-proof PW encapsulation and effective heat storage (167.6 J/g). PPy acts as a proficient photothermal converter and improves the composite material's heat transfer efficiency by establishing thermal conduction pathways, resulting in an 87.4 % enhancement in thermal conductivity compared to pure PW. The rough surface of LDH promotes multiple light reflections and scattering within the material, leading to increased light absorption by the PPy coating and achieving a photothermal conversion efficiency of up to 96.4 %. Furthermore, the high roughness of the LDH layer combined with the low surface energy of PW imparts superhydrophobic self-cleaning properties to the material, ensuring sustained effectiveness of the photothermal conversion coating over time. This research presents a viable approach for maintaining the cleanliness and efficiency of solar energy systems.

Sinoatrial node function and the role of sinoatrial conduction in the typical atrial flutter substrate

BackgroundSinoatrial node (SAN) activation and sinoatrial conduction pathways (SACPs) have been assessed in animals but not in humans. ObjectivesWe used ultrahigh-density mapping and simulated models to characterize the SAN and to investigate whether slowed SAN conduction may contribute to the atrial flutter (AFL) substrate. MethodsTwenty-seven patients undergoing electrophysiologic procedures had right atrial mapping. SAN activation patterns and conduction block were analyzed. The interaction between the SAN and the intercaval line of block (LOB) was analyzed, and right atrial simulations with different degrees of block were created to investigate arrhythmia mechanisms. ResultsFifteen AFL patients and 12 reference patients were enrolled. SACPs were identified in all patients with sinus rhythm maps. An SAN-adjacent LOB was observed in AFL patients. SAN conduction velocity was slower in AFL vs reference (0.60 m/s [0.56–0.78 m/s] vs 1.13 m/s [1.00–1.21 m/s]; P = .0021). Coronary sinus paced maps displayed an intercaval LOB in AFL patients but not in reference patients, which was completed superiorly by the SAN-adjacent LOB. Corrected sinus node recovery time was longer in AFL patients (552.3 ± 182.9 ms vs 325.4 ± 138.3 ms; P < .006) and correlated with degree of intercaval block (r = 0.7236; P = .0003). Computer modeling supported an important role of SAN-associated block in the flutter substrate. ConclusionUltrahigh-density mapping accurately identifies SAN activation and SACPs. The LOB important for typical AFL was longer in AFL patients, and when partial, it was always present inferiorly and completed superiorly because of slowed conduction across the SAN. Corrected sinus node recovery time correlated with intercaval block, suggesting a role for SAN disease in the genesis of the typical AFL substrate.

Preoperative electrocardiogram in prediction of 90-day postoperative mortality: retrospective cohort study

BackgroundThere are conflicting data on the relationship between preoperative electrocardiogram and postoperative mortality. We aimed to assess the predictive value of preoperative ECG on postoperative all-cause mortality in patients undergoing non-cardiac surgery (NCS).MethodsWe retrospectively reviewed records of hospitalized patients who underwent an internal preoperative examination and subsequent NCS in the years 2015–2021. We recorded patient comorbidities, vital functions, results of biochemical tests, ECG. The primary end point was 90-day postoperative all-cause mortality, acquired from the hospital records and the nationwide registry run by the Institute of Health Information and Statistics of the Czech Republic.ResultsWe enrolled a total of 2219 patients of mean age 63 years (48% women). Of these, 152 (6.8%) died during the 90-day postoperative period. There were statistically significant associations between increased 90-day postoperative all-cause mortality and abnormal ECG findings in resting heart rate (≥ 80 bpm, relative risk [RR] = 1.82 and ≥ 100 bpm, RR = 2.57), presence of atrial fibrillation (RR = 4.51), intraventricular conduction delay (QRS > 0.12 s, RR = 2.57), ST segment changes and T wave alterations, left bundle branch hemiblock (RR = 1.64), and right (RR = 2.04) and left bundle branch block (RR = 4.13), but not abnormal PQ and QT intervals, paced rhythm, incomplete right bundle branch block, or other ECG abnormalities. A resting heart rate (≥ 80 bpm, relative risk [RR] = 1.95 and ≥ 100 bpm, RR = 2.20), atrial fibrillation (RR = 2.10), and right bundle branch block (RR = 2.52) were significantly associated with 90-day postoperative all-cause mortality even in subgroup of patients with pre-existing cardiac comorbidities.ConclusionsPatients with abnormal preoperative ECG findings face an elevated risk of all-cause mortality within 90 days after surgery. The highest mortality risk is observed in patients with atrial fibrillation and left bundle branch block. Additionally, an elevated heart rate, right bundle branch block, and atrial fibrillation further increase the risk of death in patients with pre-existing cardiac conditions.

Impact of graphene oxide lateral sizes on the mechanical and thermal properties of carbon fiber composites

AbstractThe impact of carbon fiber (CF) composites sizing with graphene oxide (GO) to form brick‐and‐mortar structures on their mechanical properties and thermal conductivity has not been closely examined. This study systematically investigates the effect of GO sheet size on the interfacial properties and thermal conductivity of CF composites. Three sizes of GO—small (0.11 μm), medium (0.33 μm), and large (0.97 μm)—were used to modify CF surfaces via layer‐by‐layer self‐assembly, forming the brick‐and‐mortar structures. The mechanical properties were assessed through flexural tests, interlaminar shear strength (ILSS) tests and tensile tests, while thermal conductivity was measured using a thermal constant analyzer. The results revealed that medium‐sized GO (GO‐M) significantly enhanced the interfacial strength and toughness of the composites. This improvement is attributed to the orderly arrangement of GO‐M on the CF surface, which enhances stress transfer between the fiber and the matrix. In contrast, small‐sized GO (GO‐S) tended to scatter, resulting in less effective reinforcement, while large‐sized GO (GO‐L) exhibited stacking and agglomeration, limiting its reinforcement effectiveness. However, GO‐L provided the highest thermal conductivity due to the formation of continuous heat conduction pathways. These findings suggest that GO‐M offers a balanced improvement in mechanical properties, whereas GO‐L is more suitable for applications requiring high thermal conductivity. This work underscores the importance of selecting the appropriate GO sheet size to optimize the interfacial properties and thermal conductivity of CF composites, which is crucial for enhancing their performance in high‐end engineering applications, such as aerospace, automotive, and marine industries.Highlights Modification of CF composites by GO‐M sheets significantly improved toughness and strength. GO‐L sheets formed an effective heat transfer channel with the highest thermal conductivity. The study emphasized the critical role of selecting the appropriate GO sheet size to optimize the mechanical and thermal properties of CF composites.

Recovery of complete left bundle branch block in dilated cardiomyopathy after optimal heart failure treatment: a case report

Complete left bundle branch block (CLBBB) is a significant cardiac conduction abnormality often associated with dilated cardiomyopathy (DCM). This case report highlights the improvement in CLBBB and symptom relief through reverse cardiac remodeling in a patient diagnosed with DCM following an optimized heart failure treatment regimen consisting of an angiotensin-converting enzyme inhibitor, beta-blocker, and mineralocorticoid receptor antagonist. This case highlights the potential of electrical remodeling and conduction system improvement in patients with DCM receiving optimized medical therapy.

Transient Notch Activation Converts Pluripotent Stem Cell-Derived Cardiomyocytes Towards a Purkinje Fiber Fate.

Cardiac Purkinje fibers form the most distal part of the ventricular conduction system. They coordinate contraction and play a key role in ventricular arrhythmias. While many cardiac cell types can be generated from human pluripotent stem cells, methods to generate Purkinje fiber cells remain limited, hampering our understanding of Purkinje fiber biology and conduction system defects. To identify signaling pathways involved in Purkinje fiber formation, we analyzed single cell data from murine embryonic hearts and compared Purkinje fiber cells to trabecular cardiomyocytes. This identified several genes, processes, and signaling pathways putatively involved in cardiac conduction, including Notch signaling. We next tested whether Notch activation could convert human pluripotent stem cell-derived cardiomyocytes to Purkinje fiber cells. Following Notch activation, cardiomyocytes adopted an elongated morphology and displayed altered electrophysiological properties including increases in conduction velocity, spike slope, and action potential duration, all characteristic features of Purkinje fiber cells. RNA-sequencing demonstrated that Notch-activated cardiomyocytes undergo a sequential transcriptome shift, which included upregulation of key Purkinje fiber marker genes involved in fast conduction such as SCN5A, HCN4 and ID2, and downregulation of genes involved in contractile maturation. Correspondingly, we demonstrate that Notch-induced cardiomyocytes have decreased contractile force in bioengineered tissues compared to control cardiomyocytes. We next modified existing in silico models of human pluripotent stem cell-derived cardiomyocytes using our transcriptomic data and modeled the effect of several anti-arrhythmogenic drugs on action potential and calcium transient waveforms. Our models predicted that Purkinje fiber cells respond more strongly to dofetilide and amiodarone, while cardiomyocytes are more sensitive to treatment with nifedipine. We validated these findings in vitro , demonstrating that our new cell-specific in vitro model can be utilized to better understand human Purkinje fiber physiology and its relevance to disease.

Pillar-Supported 2D Layered MOFs with Abundant Active-Site Distributions for High-Performance Alkaline Supercapacitors.

The development of two-dimensional (2D) layered metal-organic frameworks (MOFs) through precise molecular-level design and synthesis has emerged as a prominent research endeavor. However, the utilization of MOFs in their pristine form as electrodes for supercapacitors poses a significant challenge due to their limited tolerance in alkaline environments. To address these issues, we have developed Co- and Cu-based pillar-layered MOFs by regulating the structure of their inner layers through introducing an alkaline N-containing "pillar" to enhance the performance of alkaline supercapacitor electrodes. From the microstructure study and theoretical calculation, the high-density redox centers and efficient chemical bonding modes of Co-MOF determine a unique electron conduction pathway, resulting in excellent energy storage performance. This study underscores the significance of chemical bonding modes and active-site distribution in enhancing the energy storage capabilities of pillar-layered MOFs in alkaline environments, presenting a promising approach for the development of high-performance MOF-based materials for supercapacitor applications.

Cardiac Conduction System as an OAR in Radiation Therapy: Doses to SA/AV Nodes and Their Reduction

PurposeDespite advancements in radiation techniques, concerns persist regarding the adverse effects of radiation therapy, particularly cardiotoxicity or radiation-induced heart disease. Recently, arrhythmogenic toxicity has come to the forefront—the impact of radiation therapy on the cardiac conduction system. Our objective was to conduct a dosimetric study and subsequently investigate the feasibility of optimizing the sinoatrial (SA) and atrioventricular (AV) nodes as organs at risk (OARs) in proton radiation therapy for non–small cell lung cancer with N3 disease. Patients and MethodsThirty-two non–small cell lung cancer patients with N3 disease undergoing proton radiation therapy were included. Sinoatrial and AV nodes, along with standard OARs, were delineated. Dosimetric analysis and optimization were performed using intensity-modulated proton therapy. ResultsPatients surpassing a predefined SA node dose threshold underwent dose optimization. Proton radiation therapy with pencil beam scanning demonstrated a significant reduction in SA and AV node doses without compromising target volume coverage or significant shift in the dose to other monitored OARs. ConclusionDose reduction to the SA and AV nodes for pencil beam scanning is a relatively simple task, and the reduction can be very substantial. Larger cohort studies and diverse radiotherapeutic modalities are needed for further validation and refinement of dose constraints.

In-situ TiO2/reduced graphene oxide double-coated LiNi0.5Co0.2Mn0.3O2 microspheres as high-performance Li-ion cathode materials

LiNi0.5Co0.2Mn0.3O2(NCM) layered materials have high energy density and large power density but also exhibit obvious capacity fading and voltage decay during the cycle. A rational surface modification design is reported in this work to address these problems. Herein, tetrabutyl titanate (TBOT) was decomposed into TiO2 by hydrolysis-condensation reaction and high-temperature calcination, thus a homogeneous coating was generated on the surface of NCM. The coating layer of TiO2 stabilizes the crystal structure. Furthermore, rGO and reduced metal (Ni, Co, Ti) would be wrapped on the surface as a highly conductive second coating, which could provide a rapid electron conduction pathway. The dual surface-modified cathode shows an outstanding discharge capacity of 163.4 mAh g−1 at 0.2 C and 120 mAh g−1 at 10 C. This dual coating strategy provides valuable insights for further study on the modification mechanisms of other layered cathode materials.

Right ventriculography to guide left bundle branch pacing in pacing-induced cardiomyopathy: a novel case report

Abstract Background There is emerging evidence for the potential utility of left bundle branch area pacing (LBBAP), as an alternative to conventional cardiac resynchronization therapy (CRT). The utility of right ventriculography by way of power injector to facilitate lead placement has not yet been reported in the literature. Case summary A 79-year-old female, with a background of poorly rate-controlled atrial fibrillation, presented with worsening dyspnoea. She had recently undergone single-chamber pacemaker insertion prior to an atrioventricular nodal (AVN) ablation, owing to failure in achieving successful CRT coronary sinus lead placement. She had clinical evidence of volume overload, and her electrocardiogram demonstrated right ventricular pacing. Echocardiography demonstrated left ventricular (LV) impairment, with an ejection fraction (EF) of 35%, and severe functional mitral regurgitation (MR). Her diagnosis was overall consistent with pacing-induced cardiomyopathy (PIC). In this patient, the use of right ventriculography, using power-injector-delivered contrast, successfully facilitated placement of an LBBAP lead, with confirmation of good threshold and sensing parameters. Following an upgrade to conduction system pacing, the patient recovered well. On recent follow-up, repeat echocardiography (24 months post initial presentation) demonstrated improved LV function (EF 45% from 35%) and only mild-to-moderate MR. Discussion In conclusion, we demonstrate the utility of right ventriculography to facilitate placement of an LBBAP lead, successfully treating a patient who developed PIC from chronic right ventricular pacing following AVN ablation.

Predictors of success in left bundle branch area pacing with stylet-driven pacing leads: a multicenter investigation.

Although left bundle branch area pacing (LBBAP) is an emerging conduction system pacing modality, it is unclear which parameters predict procedural success and how many implant attempts are acceptable. This study aimed to assess predictors of successful LBBAP, left bundle branch (LBB) capture, and factors associated with the number of LBBAP implant attempts. This retrospective observational multicenter study was conducted in Korea. LBBAP was attempted in 119 patients; 89.3% of patients had bradyarrhythmia (atrioventricular block 82.4%), and 10.7% of patients had heart failure (cardiac resynchronization therapy) indication. Procedural success and electrophysiological and echocardiographic parameters were evaluated. The acute success rate of lead implantation in LBBAP was 95.8% (114 of 119 patients) and that of LBB capture was 82.4% (98 of 119 patients). Fewer implant attempts were associated with LBBAP success (three or fewer vs. over three times, p = 0.014) and LBB capture (three or fewer vs. over three times, p = 0.010). In the multivariate linear regression, the patients with intraventricular conduction delay (IVCD) required a greater number of attempts than those without IVCD [estimates = 2.33 (0.35-4.31), p = 0.02], and the larger the right atrial (RA) size, the more the attempts required for LBBAP lead implantation [estimates = 2.08 (1.20-2.97), p < 0.001]. An increase in the number of implant attempts was associated with LBBAP procedural failure and LBB capture failure. The electrocardiographic parameter IVCD and the echocardiographic parameter RA size may predict the procedural complexity and the number of lead implant attempts for LBBAP.

Operando Decoding Ion-Conductive Switch in Stimuli-Responsive Hydrogel by Nanodiamond-Based Quantum Sensing.

Thermal-responsive hydrogels are developed as ion-conductive switchs for energy storage devices, however, the molecule mechanism of switch on/off remains unclear. Here, poly(N-isopropylacrylamide-co-acrylamide) hydrogel is synthesized as a model material and nanodiamond (ND) based quantum sensing for phase change study is developed. First, micro-scale phase separation with cross-linked mesh structure after sol-gel transition is visualized in situ and water molecules are trapped by polymer chains and on a chemically "frozen" state. Then, the nano-scale inhomogeneous distributions of viscosity, thermal conductivity and ionic mobility in hydrogel at high temperature are observed by measuring the rotation, translation and zero-field splitting of NDs. Besides, the ionic mobility of hydrogel is found to be dependent not only on temperature but also on polymer concentration. These observations suggested that the physical "wall" induced by inhomogeneous phase separation at microscopic scale blocked the ion conduction pathways, providing a potential intrinsic explanation for ion migration shut-down of ionic hydrogels at high temperature.