Thunderstorm Research Articles

Long-term clinical outcomes of remote monitoring for implantable cardioverter-defibrillators in Singapore.

Remote monitoring (RM) for cardiac implantable electronic devices is on the rise and has been shown to reduce the burden of in-clinic follow-up visits. We aimed to investigate the long-term clinical outcomes of RM versus no RM. This was a prospective, single-centre cohort study of consecutive patients with an implantable cardioverter-defibrillator (ICD) or cardiac resynchronisation therapy-defibrillator (CRT-D) followed up from 2018 to 2023. Patients who received non-ICD devices were excluded. In general, RM was offered to all patients, but uptake depended on patient preference. For data analysis, patients were stratified according to whether RM was used. The primary outcome was all-cause mortality; secondary outcomes were hospitalisation for heart failure and device therapy (shocks and electrical storm). Of 551 patients, 284 (51.5%) received RM and 267 (49.5%) did not. Baseline demographics were similar between the two arms. All-cause mortality was significantly lower in RM versus non-RM patients (hazard ratio [HR] 0.45, 95% confidence interval [CI] 0.33-0.60, P <0.001), as was hospitalisation for heart failure (HR 0.39, 95% CI 0.25-0.59, P <0.001); these remained significant after adjustment for baseline covariates. More patients on RM received appropriate antitachycardia pacing (ATP) (17.6% vs. 10.7%, P = 0.035) and appropriate shocks (24.1% vs. 14.7%, P = 0.017). The incidences of inappropriate ATP, inappropriate shocks and electrical storm were similar. More patients on RM underwent pulse generator change (34.1% vs. 10.1%, P <0.001). Remote monitoring was associated with significantly lower mortality in both ICDs and CRT-Ds and in primary and secondary indications, as well as fewer heart failure hospitalisations. This supports current guidelines recommending the use of RM in all patients with ICD or CRT-D.

Future Changes in the Vertical Structure of Severe Convective Storm Environments over the U.S. Central Great Plains

Abstract The effect of warming on severe convective storm potential is commonly explained in terms of changes in vertically integrated (“bulk”) environmental parameters, such as CAPE and 0–6-km shear. However, such events are known to depend on the details of the vertical structure of the thermodynamic and kinematic environment that can change independently of these bulk parameters. This work examines how warming may affect the complete vertical structure of these environments for fixed ranges of values of high CAPE and bulk shear, using data over the central Great Plains from two high-performing climate models (CNRM and MPI). To first order, projected changes in the vertical sounding structure are consistent between the two models: the environment warms approximately uniformly with height at constant relative humidity, and the shear profile remains relatively constant. The boundary layer becomes slightly drier (−2% to 6% relative humidity) while the free troposphere becomes slightly moister (+1% to 3%), with a slight increase in moist static energy deficit aloft with stronger magnitude in CNRM. CNRM indicates enhanced low-level shear and storm-relative helicity associated with stronger hodograph curvature in the lowest 2 km, whereas MPI shows near-zero change. Both models strongly underestimate shear below 1 km compared to ERA5, indicating large uncertainty in projecting subtle changes in the low-level flow structure in climate models. The evaluation of the net effect of these modest thermodynamic and kinematic changes on severe convective storm outcomes cannot be ascertained here but could be explored in simulation experiments. Significance Statement Severe thunderstorms and tornadoes cause substantial damage and loss of life each year, which raise concerns about how they may change as the world warms. We typically use a small number of common atmospheric parameters to understand how these localized events may change with climate change. However, climate change may alter the weather patterns that produce these events in ways not captured by these parameters. This work examines how climate change may alter the complete vertical structure of temperature, moisture, and wind and discusses the potential implications of these changes for future severe thunderstorms and tornadoes.

Predictability of Severe Convective Storm Environments in Global Ensemble Forecast System, Version 12, Reforecasts

Abstract Prediction of severe convective storms at time scales of 2–4 weeks is of interest to forecasters and stakeholders due to their impacts on life and property. Prediction of severe convective storms on this time scale is challenging, since the large-scale weather patterns that drive this activity begin to lose dynamic predictability beyond week 1. Previous work related to severe convective storms on the subseasonal time scale has mostly focused on observed relationships with teleconnections. The skill of numerical weather prediction forecasts of convective-related variables has been comparatively less explored. In this study over the United States, a forecast evaluation of variables relevant in the prediction of severe convective storms is conducted using Global Ensemble Forecast System, version 12, reforecasts at lead times of up to 4 weeks. We find that kinematic and thermodynamic fields are predicted with skill out to week 3 in some cases, while composite parameters struggle to achieve meaningful skill into week 2. Additionally, using a novel method of weekly summations of daily maximum composite parameters, we suggest that the aggregation of certain variables may assist in providing additional predictability beyond week 1. These results should serve as a reference for forecast skill for the relevant fields and help inform the development of convective forecasting tools at time scales beyond current operational products. Significance Statement Prediction of severe weather beyond 1 week in advance is of interest to stakeholders given their impacts on life and property. In this study, we evaluate 20 years of forecast data generated by a numerical model ensemble to determine whether variables relevant in severe weather forecasts can be predicted in weeks 2–4. The variables with the best skill measures generally represent large-scale weather patterns that are more predictable on longer time scales, although some manipulation of other severe weather parameters yielded additional results. We suggest that the results found in this study can inform future work that assesses the predictability of severe weather in weeks 2–4 using more complex methods such as machine learning.

Stellate Ganglion Block for Electrical Storm Associated With Takotsubo Cardiomyopathy: A Case Report

Stellate Ganglion Block for Electrical Storm Associated With Takotsubo Cardiomyopathy: A Case Report

Contemporary outcomes of catheter ablation of the structural ventricular tachycardias in severe ischemic and non‐ischemic cardiomyopathies in Turkish population

AbstractIntroductionCurrently, there are no data regarding outcomes of the catheter ablation for structural ventricular tachycardia (VT) in Türkiye. In this observational study, we aim to investigate cardiac outcomes of patients undergoing catheter VT ablation at a tertiary center in Türkiye.MethodsThis was a retrospective observational study performed at a single university center. Patients with a confirmed ischemic or non‐ischemic cardiomyopathy, undergoing structural VT ablation were included. Procedural and mid‐term outcomes were analyzed.ResultsA total of 124 patients were enrolled in the study. 54(43.5%) patients presented with an electrical storm. During the mean follow‐up of 351 ± 232 days 10(8.1%) patients experienced a recurrence. There was only one peri‐procedural death and cardiac tamponade occurred in two patients.14(11.3%) patients died during the follow‐up, most commonly due to a cardiovascular death. In the multivariate analysis only age &gt;70 was found to be correlated with death during follow‐up, with p =.008, HR = 4.923.ConclusionA good acute success with low complications was observed in patients undergoing VT ablation for structural heart disease in a tertiary center in Türkiye. Mid‐term outcomes are comparable with international studies with no difference in VT recurrence in ischemic and non‐ischemic patients. Similar to international studies, significant mid‐term mortality was observed.

Efficacy and safety of ultrasound guided stellate ganglion block: developing new clinical indications beyond electrical storm

Abstract Background Percutaneous stellate ganglion block (PSGB) is recommended by the latest European guidelines for patients with drug and ventricular tachycardia (VT) ablation refractory electrical storm (ES). Yet, due to the strong antiarrhythmic potential, combined with the good safety profile, we’ve recently used it for to the prophylaxis of ventricular arrhythmias (VAs) in high-risk patients and the prophylaxis/treatment of atrial arrhythmias in patients with acute heart failure (HF). Purpose To describe our single-center experience with PSGB usage outside the conventional indication of ES. Methods We hereby describe our single center experience with PSGB from 2/2021 to 2/2024. Results 56 patients (87% male, mean age 64 ± 12 years) received a total of 91 PSGB performed with the lateral, ultrasound (US) guided technique. Most of the procedures consisted of a single bolus anesthetic injection of lidocaine plus ropivacaine, 27% in an additional continuous infusion, mainly with ropivacaine. All procedures except for 3 in a single patient who had previously received left cardiac sympathetic denervation, were performed on the left side. Most of the patients (61%) suffered ischemic cardiomyopathy (CMP), including 11 with an acute coronary syndrome; the rest had non-ischemic CMP. 63 PSGB (69%) were performed in patients with impending or manifested cardiogenic shock (SCAI classification B or more). Mean LVEF was 24 ± 12%. Most of the procedures (n=80, 88%) were performed due to ongoing refractory VAs, yet 6 (6%) aimed to prevent major VAs in high-risk patients, mostly in the setting of recent ES (within 1 month) and need for Levosimendan to support cardiac output, in one case due to recent stereotactic VT ablation, to prevent early VAs in the phase of acute radiation induced microvascular damage. All 6 were effective in preventing clinically significant VAs. Additionally, 5 single bolus PSGBs (5%) were performed due to atrial arrhythmias with high ventricular rate despite intravenous drugs in the setting of acute HF. Specifically, 3 patients had atrial fibrillation (AF), 1 patient runs of ectopic atrial tachycardia (AT) and 1 patient 2:1 atrial flutter. Left-sided PSGB significantly reduced (≥25% reduction) ventricular rate during AF and AT but not during the single case of 2:1 atrial flutter, in 2/3 AF cases a cardioversion into sinus rhythm occurred within 40 minutes from PSGB. Only 1 (1%) major complication occurred (respiratory arrest), that was quickly and effectively treated with lipid emulsion, while minor complications were observed in 11% of PSGBs (mostly transient left arm weakness). Conclusions Our data suggest that US-guided PSGB usage, thanks to its feasibility at bed-side and good safety profile, may expand, beyond ES, to not only VAs prevention in high-risk settings, but also to prophylaxis/treatment of atrial arrhythmias in critically ill patients with acute heart failure requiring concomitant inotropic support.

Efficacy of percutaneous stellate ganglion block according to ventricular arrhythmia cycle length: a post-hoc sub-analysis of the STAR study

Abstract Background Percutaneous stellate ganglion block (PSGB) is an effective treatment for patients with electrical storm (ES). However, literature is scarce about a possible relation between ventricular arrhythmias’ cycle length and the effectiveness extent of PSGB. Purpose To assess whether the PSGB efficacy is affected by the arrhythmias’ cycle length prior to the procedure. Methods This is a post-hoc sub-analysis of the STAR study (STellate ganglion block for Arrythmic stoRm), a multicentre observational study aimed to assess PSGB’s effectiveness and safety in ES patients [1]. According to both the type and the median cycle of the latest ventricular arrhythmia before PSGB we considered 3 groups: ventricular fibrillation (VF), fast ventricular tachycardia (VT) and slowVT. The primary outcome is the number of treated arrhythmic episodes (with ATPs and/or DC-shocks) in the hour immediately after the PSGB as compared to the hour immediately before. The secondary outcome was the extent of the reduction of the number of ATPs/DC-shocks delivered from the hour before to the hour immediately after the PSGB. Results The original study included 184 PSGBs performed on 131 patients. We excluded 32 PSGBs with a continuous infusion and 13 PSGBs with an unknown VT cycle. The median VT cycle was 375 msec, so the final dataset of 139 PSGBs from 112 patients was divided as follows: 51 VF; 44 fastVT (VT cycle &amp;lt;375 msec) and 44 slowVT (VT cycle ≥375 msec). The number of treated arrhythmic episodes in the first hour after every PSGB was significantly lower compared to the first hour before in all the three groups [VF: 0 (IQR, 0-1) vs 5 (IQR, 2-8), p&amp;lt;0.001; fastVT: 0 (IQR, 0-0) vs 1 (IQR, 0-6.5), p&amp;lt;0.001; slowVT: 0 (IQR, 0-0) vs 1 (IQR, 0-4.5), p=0.001] (Figure 1). The Hodges-Lehman median difference of treated arrhythmic episodes between the hour after and before the PSGB was significantly higher in VF group [-4 (-3 to -6)] than in the fast-VT [-2 (-1 to -4)] and slow-VT [-1 (0 to -2.5)] (Figure 2). Analysing the reduction (delta less than zero) of the number of ATPs/DC-shocks from the hour before to the hour immediately after the PSGB, a significant trend was observed across the three groups (Jonckheere-Terpstra trend p&amp;lt;0.001) and a significant difference was observed comparing slow-VT vs VF [0 (IQR, -3 to 0) vs -4 (IQR, -7 to -1)] and fast-VT versus VF [-1 (IQR, -4.5 to 0) vs -4 (IQR, -7 to -1)], but not comparing slow-VT versus fast-VT [0 (IQR, -3 to 0) vs -1 (IQR, -4.5 to 0)]. VF was a predictor of the reduction of treated arrhythmic episodes at univariable analysis and after correction for the number of treated arrhythmic episodes in the hour immediately before PSGB and of left ventricular ejection fraction (OR 7.8, 95%CI 2.1-28.6). Conclusion PSGB is an effective treatment for ES in patients with all type of ventricular arrhythmias. However, its effectiveness was more pronounced in patients with VF or rapid ventricular tachycardia.

Mineralocorticoid receptor antagonist therapy in patients with ischemic heart failure and ventricular tachycardia: a comparative analysis of spironolactone vs. eplerenone

Abstract Background Mineralocorticoid receptor antagonists (MRAs) are a cornerstone of heart failure therapy and have been shown to reduce the incidence of sudden cardiac death. However, a direct comparison between spironolactone and eplerenone in patients who present ventricular tachycardia (VT) is lacking. Purpose This study aimed to compare the effect of spironolactone and eplerenone on VT recurrence in patients with ischemic heart disease (IHD) hospitalized for VT episodes. Methods Our data utilized a registry of 405 patients with IHD and HF, who were hospitalized for an episode of sustained VT and received MRA therapy. We performed propensity score matching based on age, hypertension, diabetes, history of acute myocardial infarction, left ventricular ejection fraction (LVEF) and presentation with incessant VT. The matched population included 200 patients, stratified into two equivalent groups. Cox regression analysis was performed to identify predictors of VT recurrence, with Kaplan-Meier curves facilitating time-to-event analyses. Results The median age was 69 years and the majority (91%) were male. One-third had an ICD, and 41 patients (20%) had CRT. The median LVEF was 30%, 23 patients (12%) presented with an electrical storm, while 18 (9%) had incessant VT. VT led to hemodynamic instability in 91 cases (46%). Ablation was performed in 47 patients (24%), while 1 required mechanical circulatory support. Ablation was performed in 47 patients (24%), while 1 required mechanical circulatory support. Patients were followed for at least a year and median follow-up time was 414 days. A total of 78 patients had VT recurrence and 117 patients died. Eplerenone use significantly reduced the risk of VT recurrence compared to spironolactone (HR: 0.59 [0.37-0.93], p=0.023). This effect was consistent in the multivariate model as well (p=0.007). Conclusions Eplerenone use may confer a greater protective effect against VT recurrence in patients with IHD and sustained VT. Further studies are required to confirm these preliminary findings.

Clinical profile of patients undergoing percutaneous stellate ganglion block for electrical storm and association with antiarrhythmic efficacy

Abstract Background Percutaneous stellate ganglion block (PSGB) usage for patients with refractory ventricular arrhythmias (VAs) in form of electrical storm (ES) is in quickly expanding. The clinical profile of patients and the potential association with the antiarrhythmic efficacy of the procedure are mostly unexplored. Purpose To better characterize clinical profile and potential association with antiarrhythmic efficacy of patients undergoing PSGB for ES. Methods Patients undergoing PSGB for ES in our Center from 2/2021 to 2/2024 were enrolled; all the dynamic variables were evaluated in a per procedure analysis. Results 45 patients (93% male, 64 ± 10 years) received a total of 80 PSGB performed with the lateral, ultrasound (US) guided technique; most PSGB consisted of a single bolus anesthetic injection (lidocaine + ropivacaine), 26% in an additional continuous infusion, mostly with ropivacaine. All procedures except for 3 in a single patient who had previously received left cardiac sympathetic denervation, were performed on the left side. Most of the patients (60%) suffered ischemic cardiomyopathy (CMP), including 10 with an acute coronary syndrome; the rest had non-ischemic CMP; 60% had an ICD. The type of VAs was ventricular tachycardia (VTs) only in 86% of the procedures (cycle length 404 ± 143 msec), VT and VF in 10% and VF only in 3 (4%). Most PSGB (81%) were performed in the setting of impending or manifest cardiogenic shock (SCAI classification B or more), including 20% with sepsis. Cardiac US performed before (within 12 hours) each PSGB showed a severely depressed left ventricular (LV) function (mean LVEF 22 ± 10%, mean LV outflow tract velocity time integral 12 ± 4 cm), calculated at a mean heart rate of 81 ± 16 bpm. Mean LVEDV was 252 ± 104 ml, 79% had mitral regurgitation (MR) ≥2+/4+ (including 39% severe MR), 50% had ≥ moderate diastolic dysfunction, 29% had right ventricular dysfunction (mean fractional areal change 33± 7%). Most cases (75%) experienced a complete VAs suppression (sustained or treated) in the 12 hours after PSGB; only 3/80 cases required additional urgent antiarrhythmic strategies (intra-aortic ballon pump in one case, urgent pacing in another one, urgent revascularization in the last one). None of the assessed clinical or echocardiographic characteristics was significantly associated with VT cycle length or the response to PSGB. Only 1 (1%) major complication occurred (respiratory arrest), that was quickly and effectively treated with lipid emulsion. Conclusions PSGB in our Center was mostly performed in the setting of primary impending or manifest cardiogenic shock with severely impaired cardiac function, with an excellent safety profile. None of the assessed clinical or echocardiographic variables were associated with response to PSGB. Our data, despite preliminary and requiring confirmation, suggests always considering PSGB in the urgent/emergent setting independently from patients’ characteristics.

Multiday Soil Moisture Persistence and Atmospheric Predictability Resulting From Sahelian Mesoscale Convective Systems

AbstractSkill in predicting where damaging convective storms will occur is limited, particularly in the tropics. In principle, near‐surface soil moisture (SM) patterns from previous storms provide an important source of skill at the mesoscale, yet these structures are often short‐lived (hours to days), due to both soil drying processes and the impact of new storms. Here, we use satellite observations over the Sahel to examine how the strong, locally negative, SM‐precipitation feedback there impacts rainfall patterns over subsequent days. The memory of an initial storm pattern decays rapidly over the first 3–4 days, but a weak signature is still detected in surface observations 10–20 days later. The wet soil suppresses rainfall over the storm track for the first 2–8 days, depending on aridity regime. Whilst the negative SM feedback initially enhances mesoscale rainfall predictability, the transient nature of SM likely limits forecast skill on sub‐seasonal time scales.

Efficacy of stellate ganglion block in treatment of electrical storm: a systematic review and meta-analysis.

Electrical storm (ES) is a life-threatening condition of recurrent ventricular arrhythmias (VA) in a short period of time. Percutaneous stellate ganglion blockade (SGB) is frequently used - however the efficacy is undefined. The objective of our systematic review was to determine the efficacy of SGB in reducing VA events and mortality among patients with ES. A search of Medline, EMBASE, Scopus, CINAHL and CENTRAL was performed on February 29,2024 to include studies with adult patients (≥ 18 years) with ES treated with SGB. Our outcomes of interest were VA burden pre- and post-SGB, and in-hospital/30-day mortality. A total of 553 ES episodes in 542 patients from 15 observational studies were included. Treated VAs pre- and post-SGB were pooled from eight studies including 383 patients and demonstrated a decrease from 3.5 (IQR 2.25-7.25) to 0 (IQR 0-0) events (p = 0.008). Complete resolution after SGB occurred in 190 of 294 patients (64.6%). Despite this, in-hospital or 30-day mortality remained high occurring in 140 of 527 patients (random effects prevalence 22%). Repeat SGB for recurrent VAs was performed in 132 of 490 patients (random effects prevalence 21%). In conclusion, observational data suggests SGB may be effective in reducing VAs in ES. Definitive studies for SGB in VA management are needed.Study protocol: PROSPERO - registration number CRD42023430031.

"Hot phase" clinical presentation of biventricular arrhythmogenic cardiomyopathy: when the perfect electrical storm spontaneously stops.

An 18-year-old male presented with syncope during a training break. Post-syncope, he developed effort dyspnea, which he associated with the Pfizer-BioNTech COVID-19 vaccine received a week earlier. Electrocardiogram showed T inversion in V1-V3, III, and aVF, while 24-hour Holter monitoring revealed frequent ventricular premature beats. A transthoracic echocardiogram showed severe biventricular dilation and mild left ventricular (LV) dysfunction. Cardiac magnetic resonance (CMR) imaging confirmed these findings, showing moderate right ventricular (RV) systolic dysfunction with akinesia of the inferior and inferolateral walls. T2 hypersignal in the middle segment of the inferior inferior interventricular septum suggested myocardial edema. Extensive transmural late gadolinium enhancement was noted in the RV and LV walls. An implantable loop recorder was implanted. Three months later, the patient was admitted with palpitations, fever, and a positive SARS-CoV-2 test. Sustained ventricular tachycardia (VT) episodes were documented and managed with amiodarone and β-blockers. Follow-up CMR showed a slight improvement in LV ejection fraction and resolution of edema. A single-chamber implantable cardioverter-defibrillator (ICD) was implanted. Genetic testing for arrhythmogenic RV cardiomyopathy (ARVC) was negative, and family screening was normal. Two years later, pre-syncope episodes occurred, and ICD interrogation revealed nonsustained VT. The patient is awaiting VT ablation. This case highlights the diagnostic and therapeutic challenges of ARVC, particularly in differentiating it from myocarditis. The "hot-phase" presentation, vaccine association, and subsequent SARS-CoV-2 infection added complexity. CMR was crucial for diagnosis, and VT management required a combination of medical therapy and invasive procedures.

Use of Esmolol to treat resistant electrical storm in a patient with decompensated heart failure

BackgroundVentricular tachycardia storm is a syndrome defined by the presence of at least three episodes of ventricular tachycardia over a 24-h period, requiring termination by intervention. Standard therapy consists initially of using intravenous betablockers (if left ventricular ejection fraction is preserved) and Amiodarone, in addition to intravenous Lidocaine (in case of ischemic etiology) and light sedation. In the present case, a ventricular tachycardia storm episode is terminated by Esmolol, a particular intravenous betablocker, despite acute decompensated heart failure.Case presentationWe report the case of an 89-year-old patient presenting for a ventricular tachycardia storm and acute heart failure with reduced left ventricle ejection fraction of coronary ischemic origin that persisted despite coronary revascularization, oral betablocker, intravenous Amiodarone and Lidocaine, light sedation, and multiple electrical cardioversion. Emergency catheter ablation was not feasible due to meteorological conditions. We decided to use an intravenous betablocker despite the presence of acute heart failure. We favored use of intravenous Esmolol over other intravenous betablockers due to its short half-life and thus his rapid elimination, a unique characteristic for Esmolol. Intravenous Esmolol has successfully terminated the ventricular tachycardia without causing cardiogenic shock.ConclusionsIntravenous Esmolol can be used safely in patients with acute decompensated heart failure to terminate an electrical storm after failure of other measures. Close monitoring of the patient remains essential.

Future Derecho Potential in the United States

Abstract This study uses high-resolution, convection-permitting, dynamically downscaled regional climate simulation output to assess how long-lived, convectively induced, extratropical windstorms known as derechos may change across the CONUS during the 21st century. Three 15-year epochs including a historical period (1990 – 2005), and two, separate late-21st century periods (2085 – 2100) employing intermediate (RCP 4.5) and pessimistic (RCP 8.5) greenhouse gas concentration scenarios are evaluated. A mesoscale convective system (MCS) identification and tracking tool catalogs derecho candidates across epochs using simulated radar reflectivity and maximum 10-meter wind speed as a proxy for near-surface severe wind gusts. Results indicate that MCS-based windstorms, including derechos, are more frequent, widespread, and intense in both future climate scenarios examined for most regions of the central and eastern CONUS. Increases are suggested across all parts of the year, with significant changes in populations concentrated during the early spring and summer months, suggesting the potential for a longer, more extreme MCS windstorm season. This research provides insights for forecasters, emergency managers, and wind-vulnerable stakeholders on how these events may change across the 21st century so that they may mitigate, adapt to, and become resilient against severe convective storm perils.

Development of a Storm-Tracking Algorithm for the Analysis of Radar Rainfall Patterns in Athens, Greece

This research work focuses on the development and application of a storm-tracking algorithm for identifying and tracking storm cells. The algorithm first identifies storm cells on the basis of reflectivity thresholds and then matches the cells in the tracking procedure on the basis of their geometrical characteristics and the distance within the weather radar image. A sensitivity analysis was performed to evaluate the preferable thresholds for each case and test the algorithm’s ability to perform in different time step resolutions. Following this, we applied the algorithm to 54 rainfall events recorded by the National Technical University X-Band weather radar, the rainscanner system, from 2018 to 2023 in the Attica region of Greece. Testing of the algorithm demonstrated its efficiency in tracking storm cells over various time intervals and reflecting changes such as merging or dissipation. The results reveal the predominant southwest-to-east storm directions in 40% of cases examined, followed by northwest-to-east and south-to-north patterns. Additionally, stratiform storms showed slower north-to-west trajectories, while convective storms exhibited faster west-to-east movement. These findings provide valuable insights into storm behavior in Athens and highlight the algorithm’s potential for integration into nowcasting systems, particularly for flood early warning systems.

Torsades de Pointes electrical storm in children with KCNH2 mutations

Congenital long QT syndrome (LQTS) is a genetic heart disorder, which may lead to life-threatening arrhythmias, especially in children. Here, we reported two children who were initially misdiagnosed with epilepsy and experienced Torsades de Pointes (TdP) cardiac electrical storm (ES). Through whole exome sequencing (WES), we identified two Potassium voltage-gated channel subfamily H member 2 (KCHN2) mutations (c.1841 C > T and c.1838 C > T) respectively in a 6-year-old boy and a 13-year-old girl. Clinical data indicated that the QT interval was significantly prolonged, the T-wave pattern of chest V5-V6 leads and limb leads were inverted. Our study suggests that patients with epilepsy, especially those refractory epilepsy with atypical features, need comprehensive evaluation of cardiovascular function. KCNH2 mutation in pore region, QT interval prolongation and T wave inversion are high risk factors for ES. For LQT2 patients with ES, Nadolol and left cardiac sympathetic denervation are indicated, sometimes with an ICD.

Recent developments in tornado theory and observations.

This article critically reviews research on tornado theory and observations over the last decade. From the theoretical standpoint, the major advances have come through improved numerical-simulation models of supercell convective storms, which contain the tornado's parent circulation. These simulations are carried out on a large domain (to capture the supercell's circulation system), but with high grid resolution and improved representations of sub-grid physics (to capture the tornado). These simulations offer new insights into how and why tornadoes form in some supercells, but not others. Observational advances have come through technological improvements of mobile Doppler radars capable of rapid scanning and dual-polarization measurements, which offer a much more accurate view of tornado formation, tornado structure, and the tornado's place within its parent supercell.

Geomorphic characteristics influencing post-fire river response in mountain streams

As wildfires increase in frequency and severity, there is a growing interest in understanding river response to the wildfire disturbance cascade. Numerous headwater mountain catchments within the Cache la Poudre (Poudre) River basin in the Colorado Front Range, USA burned severely and extensively during the 2020 Cameron Peak fire. Debris flows and flash floods occurred in many of these catchments triggered by convective storms after the fire. The downstream effects of the floods and sediment varied along a continuum from attenuated and largely contained within the catchment, to releasing substantial volumes of water and sediment to the Poudre River. We conceptualize these catchments as exhibiting decreasing absorbance of post-fire disturbance along the continuum described above based on the geomorphic evidence of relative sediment export. We conceptualize characteristics on different spatial scales as driving or resisting response to disturbance and therefore impacting the absorbing capacity (ability to attenuate post-fire fluxes) of the catchment. As the magnitude of resisting characteristics increases at the catchment, inter- and intra- reach scales, we hypothesize that a catchment will increasingly absorb the impacts of the wildfire disturbance cascade. We conducted longitudinally continuous surveys to measure reach-scale characteristics within each study catchment. We focus on the catchment- and reach-scale geomorphic, vegetation, and burn characteristics. The floods observed at the study catchments illustrate fire influencing the elevation above which rainfall-induced flooding occurs due to the efficient conveyance of water from hillslopes to channels after wildfire. Results suggest that inter- and intra-reach spatial heterogeneity are better aligned with absorbance capacity than catchment-scale characteristics: greater absorbing capacity is associated with greater longitudinal variations in floodplain/channel width and more reaches with wide floodplains, low channel gradients, beaver-modified topography, and multi-stem deciduous vegetation. We connect the capacity to absorb the impacts of disturbance as informing the catchment response to wildfire disturbance.

A Priori Test of Scale-Similarity Parameterizations for Subgrid-Scale Fluxes in Convective Storms

Abstract This study evaluates a parameterization scheme for subgrid-scale (SGS) fluxes based on the scale-similarity assumption and employing a large-eddy simulation of an idealized back-building convective system. In this parameterization, the SGS fluxes are decomposed into the “Leonard term,” which depends only on the resolved scale components, the “Reynolds term,” which depends only on the SGS components, and the “cross term,” which corresponds to the interaction between the resolved scale and SGS components. Assuming a linear relationship between the Leonard term and the Reynolds and cross terms, SGS fluxes are expressed as the product of an empirical coefficient and the Leonard term. The Leonard term reasonably represents the SGS flux derived by a smooth filter operation, including the countergradient vertical SGS transport of potential temperature, which cannot be represented by a traditional eddy-diffusivity model. The dependence of the empirical coefficient on filter width is also evaluated. This dependence is related mainly to the Reynolds term, the magnitude of which varies widely with the filter width. The estimation based on the spectral decomposition of the Reynolds term explains the obtained dependence of the empirical coefficient for the vertical flux on filter width. In contrast, the variation of the empirical coefficient with filter width is not required to obtain the horizontal flux. For the parameterization of SGS fluxes in kilometer-scale models that use finite difference or volume methods, the Leonard term is expressed by the horizontal gradient of variables on a discrete grid. The Leonard term on a discrete grid also accurately represents the amplitude and spatial pattern of the SGS flux. Significance Statement Kilometer-scale numerical weather prediction models can reproduce deep convection explicitly. However, they cannot reproduce smaller inner structures within this deep convection. Therefore, a parameterization scheme that can express the nature of the transport associated with such structures is required. Using a large-eddy simulation with a horizontal resolution sufficient to express such inner structures, we evaluated a parameterization based on the scale similarity assumption, including an empirical coefficient. Based on spectral decomposition, we quantitatively estimated the relationship between the empirical coefficient and grid spacing. Our results provide guidance in selecting the value of the empirical coefficient in this parameterization.

Magnetic Resonance-Guided StereotacticRadioablation for SeptalVentricular Tachycardias.

Stereotactic arrhythmia radioablation (STAR) was introduced to treat ventricular tachycardia (VT) refractory to catheter ablation. No data are now available in the septal VT substrate setting, representing a challenge when using conventional techniques. This study sought to evaluate the arrhythmic burden in patients with septal VT treated with magnetic resonance-guided STAR (MRgSTAR). We enrolled consecutive patients with septal VT substrate. The therapy target was achieved by combining anatomic/functional and electrophysiologic information. Patients were treated with a single fraction of 25Gy adopting MRgSTAR. All patients were clinically followed up, and all implantable cardiac devices were remotely monitored. The efficacy outcome included recurrences of any sustained VT beyond the 6-week blanking period after MRgSTAR. The safety outcome was the incidence of adverse events and atrioventricular block. We included 11 patients with septal substrate VT (median age: 68 years; Q1-Q3: 64.5-78 years; 100% male). Clinical presentation was an electrical storm in 81.8% of patients. No complications occurred after MRgSTAR, and 6(54.5%) patients were discharged on the same day of treatment. During a mean follow-up of 12 ± 6months, the efficacy outcome occurred in 3 (27.3%) cases. A significative reduction of implantable cardioverter-defibrillator (ICD) therapy (23.6 before MRgSTAR vs 1.7 after MRgSTAR; P< 0.001) was observed. Left ventricular ejection fraction increased significantly after treatment (38% [Q1-Q3: 33.5%-42.0%] before MRgSTAR vs 43.8% [Q1-Q3: 35%-47%] after MRgSTAR; P=0.04). No adverse effects were observed in the implantable cardioverter-defibrillator and lead system; in the 7 patients with preserved atrioventricular conduction, no atrioventricular block was reported. MRgSTAR represents a safe and effective strategy for treating septal VT.