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Targeting the atrioventricular nodal slow pathway (AVNsp) is the standard treatment in catheter ablation procedures for atrioventricular nodal reentrant tachycardia (AVNRT). However, significant anatomical variability in Koch's triangle poses challenges for precise ablation and increases the risk of atrioventricular block (AVB). Previous studies have reported that the AVNsp visualization strategy reduces the incidence of AVB, however, these studies were conducted in pediatric patients or with the energy of cryoablation. However, the safety and effectiveness of this strategy in adults undergoing radiofrequency ablation (RFA) remains unclear. This study aimed to evaluate the safety and effectiveness of high-density mapping (HDM)-guided AVNsp visualization strategy for AVNRT ablation compared to the conventional approach. We retrospectively analyzed data from 149 AVNRT patients across 3 hospitals in China. Patients were divided into 2 groups: experimental group (i.e. treated with the HDM-guided AVNsp visualization strategy, n = 88) and control group (i.e. treated with the traditional mapping and ablation strategy, n = 61). Procedural parameters, complication rates, and long-term outcomes were compared. The experimental group required fewer ablation points (4.8 ± 3.6 vs 8.5 ± 7.7, p = 0.003), shorter total ablation time (284 ± 178 s vs 408 ± 345 s, p = 0.028), and reduced procedure time (41.4 ± 14.2 min vs 51.5 ± 27.2 min, p = 0.009) compared with the control group. No cases of AVB occurred in the experimental group, while the control group reported 5 (8.2%) transient AVB and 1 (1.6%) persistent first-degree AVB after procedure. After a mean follow-up of 488 ± 246 days, no recurrences of AVNRT were observed in either group. In conclusion, for adult patients with AVNRT, the AVNsp visualization strategy enhances the safety and effectiveness of RFA by reducing procedure time and minimizing the risk of AVB.

Large constellations of small satellites will significantly increase the number of objects orbiting the Earth. Satellites burn up at the end of service life during reentry, generating aluminum oxides as the main byproduct. These are known catalysts for chlorine activation that depletes ozone in the stratosphere. We present the first atomic‐scale molecular dynamics simulation study to resolve the oxidation process of the satellite's aluminum structure during mesospheric reentry, and investigate the ozone depletion potential from aluminum oxides. We find that the demise of a typical 250‐kg satellite can generate around 30 kg of aluminum oxide nanoparticles, which may endure for decades in the atmosphere. Aluminum oxide compounds generated by the entire population of satellites reentering the atmosphere in 2022 are estimated at around 17 metric tons. Reentry scenarios involving mega‐constellations point to over 360 metric tons of aluminum oxide compounds per year, which can lead to significant ozone depletion. Plain Language Summary With ongoing plans for many constellations of small satellites, the number of objects orbiting the Earth is expected to continue increasing in the foreseeable future. At the end of service life, satellites are disposed into the atmosphere, burning up during the process and generating aluminum oxides, which are known to accelerate ozone depletion. The environmental impacts from the reentry of satellites are currently poorly understood. This paper investigates the oxidation process of the satellite's aluminum content during atmospheric reentry utilizing atomic‐scale molecular dynamics simulations. We find that the population of reentering satellites in 2022 caused a 29.5% increase of aluminum in the atmosphere above the natural level, resulting in around 17 metric tons of aluminum oxides injected into the mesosphere. The byproducts generated by the reentry of satellites in a future scenario where mega‐constellations come to fruition can reach over 360 metric tons per year. As aluminum oxide nanoparticles may remain in the atmosphere for decades, they can cause significant ozone depletion. Key Points We present the first atomic‐scale molecular dynamics simulation of high‐temperature aluminum ablation during reentry from low‐Earth orbit The amount of aluminum oxide nanoparticles generated is quantified and the accumulation in the atmosphere is estimated The long‐term accumulation of aluminum oxides from reentering satellites can cause significant ozone depletion

We aimed to determine the effects of isoproterenol on arrhythmia recurrence in atrioventricular nodal re‐entrant tachycardia (AVNRT) patients treated with catheter ablation. The present randomized controlled clinical trial was conducted on AVNRT patients candidates for radiofrequency ablation (RFA). The patients were randomly assigned to receive isoproterenol (0.5–4 μg/min) or not (control group) for arrhythmia re‐induction after ablation. The results of the electrophysiological (EP) study, the ablation parameters, and the arrhythmia recurrence rate were recorded. We evaluated 206 patients (53 males and 153 females) with a mean (SD) age of 49.87 (15.5) years in two groups of isoproterenol (n = 103) and control (n = 103). No statistically significant difference was observed between the two studied groups in age, gender, EP study, and ablation parameters. The success rate of ablation was 100% in both groups. During ~16.5 months of follow‐up, one patient (1%) in the isoproterenol group and four patients (3.8%) in the control group experienced AVNRT recurrence (HR = 0.245; 95% confidence interval [CI], 0.043–1.418; p = .173). Based on the Kaplan–Meier analysis, there was no significant difference in the incidence rate of arrhythmia recurrence during the follow‐up period between the two studied groups (p = .129). Additionally, there were no significant differences between the arrhythmia's recurrence according to age, gender, junctional rhythm, type of AVNRT arrhythmia, and DAVN persistence after ablation. Although isoproterenol administration for arrhythmia re‐induction after ablation did not alleviate the treatment outcomes and arrhythmia recurrence following RFA in AVNRT patients, further studies with a larger sample size and a longer duration of follow‐up are necessary. According to the findings, the presence or absence of isoproterenol administration for arrhythmia re‐induction after ablation did not ameliorate the treatment outcomes and arrhythmia recurrence following radiofrequency ablation in atrioventricular nodal re‐entrant tachycardiapatients. However, further clinical trials with larger sample sizes and longer duration of follow‐up are necessary to confirm our findings.

Due to its safety profile, cryoablation (Cryo) for atrioventricular nodal reentrant tachycardia (AVNRT) is more commonly preferred over radiofrequency (RF) ablation in children in recent years. Recent studies demonstrated high long-term success rates comparable to radiofrequency ablation. The aim of this prospective study was to compare the efficacy and safety of an 8-mm-tip versus 6-mm-tip Cryo catheter in the treatment of AVNRT in children. A total of 125 consecutive patients over 10 years of age with AVNRT were included. EnSite system (St. JudeMedical, St Paul, MN, USA) was used to reduce or eliminate fluoroscopy. The acute procedural success was 100% in both groups. The prodecure duration for the 8-mm-tip group was shorter (151.6 ± 63.2 vs. 126.6 ± 36.7 min, p  < 0.01, respectively). Fluoroscopy was used in only 7 patients. The mean follow-up duration was 14.6 ± 8.4 months (median 13.5 months, min. 3 months and max. 27 months). The recurrence rate for AVNRT was also comparable between the two groups (6-mm tip: 9.6 vs. 8-mm tip: 8%). Cryo of AVNRT is a safe and effective procedure with comparable acute and mid-term follow-up success rates using 6-mm and 8-mm-tip catheters in children. In addition, procedure duration is shorter with an 8-mm-tip Cryo catheter.

Introduction A 30‐year‐old woman with a history of prior ablation for a concealed left posteroseptal accessory pathway (AP) presented with incessant narrow QRS tachycardia, highlighting a rare complication of incomplete AP ablation. Methods and Results Adenosine transiently terminated the tachycardia, which recurred immediately. Electrophysiology study confirmed orthodromic atrioventricular reentry tachycardia (AVRT) due to a slow‐conducting AP at the previously ablated site. Three‐dimensional mapping localized the AP to the left posteroseptal region, and radiofrequency ablation at the shortest VA interval successfully eliminated the arrhythmia. Conclusion This case illustrates incessant AVRT caused by an iatrogenic slow‐conducting posteroseptal accessory pathway following incomplete ablation. Recognition of this mechanism is important to guide appropriate repeat ablation and prevent tachycardia‐induced cardiomyopathy. Background: A 30‐year‐old woman with a history of left posteroseptal accessory pathway (AP) ablation presented with 4 days of persistent palpitations. Clinical Course: (1) ECG: Initial ECG showed incessant narrow QRS tachycardia. (2) Intervention: Intravenous adenosine transiently restored sinus rhythm but tachycardia recurred immediately. (3) Diagnosis: Electrophysiology study confirmed orthodromic atrioventricular reentrant tachycardia (AVRT) mediated by an iatrogenic slow‐conducting posteroseptal AP. (4) Localization: 3D mapping identified the slow AP at the prior ablation site (shortest VA interval). (5) Treatment: Radiofrequency ablation at the mapped site successfully eliminated retrograde AP conduction, terminating tachycardia. Conclusion: Incomplete ablation may lead to iatrogenic slow‐conducting APs, causing incessant AVRT—repeat ablation targeting the mapped site is curative.

This study proposes a novel fault accommodation scheme for the strong coupled attitude system of the hypersonic reentry vehicle (HRV) with both actuator drift and loss of efficiency. A general coupling/fault/uncertainty effect-triggered control concept is first introduced for the HRV attitude tracking system to improve its robustness and dynamic performance, which can be derived easily via Lyapunov stability. The design of such a control approach is based on an improved adaptive disturbance observer (ADO) to estimate the lumped uncertainties and actuator faults. The proposed scheme can achieve graceful degradation in tracking performance for the fault-tolerant control system by eliminating the detrimental uncertainty and actuator fault while keeping the beneficial uncertainty and actuator fault. A detailed design procedure has been presented with consideration of the implementation problem. Simulation results obtained on the HRV have demonstrated the effectiveness of the approach proposed.

In this paper, the terminal guidance problem of unpowered lifting reentry vehicle to stationary target is studied. Based on the requirement of attacking the target with high precision and high impact angle constraint, a fractional-order theory combined sliding mode guidance law is proposed. Its sliding surface is specially designed to satisfy the requirements in the terminal guidance phase. The novel fractional-order sliding mode guidance law is established in both two-dimensional environment and three-dimensional environment; then, the systems are proved to be asymptotically stable according to the Lyapunov stability principle. Finally, compared with the one without fractional-order term, experiments show the novel guidance law has better stability. Monte Carlo simulation verifies that the designed guidance law is more robust against the disturbance of random noise and ensures higher precision in terms of impact angle error and miss distance.

Abstract Purpose Radiofrequency (RF) catheter ablation of the slow pathway (SP) in atrioventricular nodal reentry tachycardia (AVNRT) is highly effective; however, it may require prolonged fluoroscopy and RF time. We postulated that visualization of the SP region with intracardiac echocardiography (ICE) could decrease ablation time, minimize radiation exposure, and facilitate SP ablation compared to the standard, fluoroscopy-guided approach.MethodsIn our study, we randomized 91 patients undergoing electrophysiologic study and SP ablation for AVNRT into 2 groups: fluoroscopy-only (n = 48) or ICE-guided (n = 43) group. Crossover to ICE-guidance was allowed after 8 unsuccessful RF applications.ResultsMapping plus ablation time (mean ± standard deviation: 18.8 ± 16.1 min vs 11.6 ± 15.0 min, p = 0.031), fluoroscopy time (median [interquartile range]: 4.9 [2.93–8.13] min vs. 1.8 [1.2–2.8] min, p < 0.001), and total ablation time (144 [104–196] s vs. 81 [60–159] s, p = 0.001) were significantly shorter in the ICE group. ICE-guidance was associated with reduced radiation exposure (13.2 [8.2–13.4] mGy vs. 3.7 [1.5–5.8] mGy, p < 0.001). The sum of delivered RF energy (3866 [2786–5656] Ws vs. 2283 [1694–4284] Ws, p = 0.002) and number of RF applications (8 [4.25–12.75] vs. 4 [2–7], p = 0.001) were also lower with ICE-guidance. Twelve (25%) patients crossed over to the ICE-guided group. All were treated successfully thereafter with similar number, time, and cumulative energy of RF applications compared to the ICE group. No recurrence occurred during the follow-up.ConclusionsICE-guidance during SP ablation significantly reduces mapping and ablation time, radiation exposure, and RF delivery in comparison to fluoroscopy-only procedures. Moreover, early switching to ICE-guided ablation seems to be an optimal choice in challenging cases.

Congenitally corrected transposition of the great arteries (ccTGA) is associated with various types of arrhythmia, including supraventricular tachycardia (SVT) and complete atrioventricular block (cAVB). Our study aims to characterize the arrhythmia burden, associated risk factors, arrhythmia mechanisms, and the long-term follow-up results in patients with ccTGA in a large Asian cohort. We enrolled 104 patients (43 women and 61 men) diagnosed with ccTGA at our institution. The mean age at last follow-up was 20.8 years. For 40 patients (38%) with tachyarrhythmia, paroxysmal SVT (PSVT) and atrial arrhythmia were observed in 17 (16%) and 27 (26%) patients, respectively, with 4 patients (4%) having both types of SVT. The 20-year and 30-year SVT-free survival rates were 68% and 54%, respectively. Seven patients (7%) developed cAVB: 2 (2%) developed spontaneously, and the other 5 (5%) was surgically complicated (surgical risk of cAVB: 7%, all associated with ventricular septal defect repair surgery). PSVT was mostly associated with accessory pathways (5/9) but also related to twin atrioventricular nodal reentry tachycardia (3/9) and atrioventricular nodal reentry tachycardia (1/9). Most of the accessory pathways were located at tricuspid valve (9/10). Catheter ablation successfully eliminated all PSVT substrates (10/10) and most of the atrial arrhythmia substrates (3/5), with low recurrence rate. The arrhythmia burden in patients with ccTGA is high and increases over time. However, cAVB incidence was relatively low and kept stationary in this Asian cohort. The mechanisms of SVT are complicated and can be controlled through catheter ablation.

Mechanical strain regulates the development organization, and function of multicellular tissues, but mechanisms linking mechanical strain and cell-cell junction proteins to cellular responses are poorly understood. Here, we showed that mechanical strain applied to quiescent epithelial cells induced rapid cell cycle reentry, mediated by independent nuclear accumulation and transcriptional activity of first Yap1 and then β-catenin. Inhibition of Yap1- and β-catenin-mediated transcription blocked cell cycle reentry and progression through G₁ into S phase, respectively. Maintenance of quiescence, Yap1 nuclear exclusion, and β-catenin transcriptional responses to mechanical strain required E-cadherin extracellular engagement. Thus, activation of Yap1 and β-catenin may represent a master regulator of mechanical strain-induced cell proliferation, and cadherins provide signaling centers required for cellular responses to externally applied force.