Fecal calprotectin: A novel predictor of ulcerated esophageal injury after atrial fibrillation catheter ablation.

BACKGROUND: Atrial esophageal fistula (AEF) is a lethal complication that can occur post atrial fibrillation (AF) ablation. Esophageal injury (EI) is likely to be the initial lesion leading to AEF. Endoscopic examination is the gold standard for a diagnosis of EI but extensive endoscopic screening is invasive and costly. This study was conducted to determine whether fecal calprotectin (Fcal), a marker of inflammation throughout the intestinal tract, may be associated with the existence of esophageal injury. METHODS: This diagnostic study was conducted in a cohort of 166 patients with symptomatic AF undergoing radiofrequency catheter ablation from May 2020 to June 2021. Fcal tests were performed 1-7 days after ablation. All patients underwent endoscopic ultrasonography 1 or 2 days after ablation. RESULTS: The levels of Fcal were significantly different between the EI and non-EI groups (404.9 µg/g (IQR 129.6-723.6) vs. 40.4 µg/g (IQR 15.0-246.2), p < .001). Analysis of ROC curves revealed that a Fcal level of 125 µg/g might be the optimal cut-off value for a diagnosis of EI, giving a 78.8% sensitivity and a 65.4% specificity. The negative predictive value of Fcal was 100% for ulcerated EI. CONCLUSIONS: The level of Fcal is associated with EI post AF catheter ablation. 125 µg/g might be the optimal cut-off value for a diagnosis of EI. Negative Fcal could predict the absence of ulcerated EI, which could be considered a precursor to AEF.

Respiratory control minimizes diaphragmatic contraction and dry cough during pulsed-field ablation of atrial fibrillation.

AIMS: Pulsed-field ablation (PFA) is a promising new ablation modality to treat atrial fibrillation. However, PFA can cause varying degrees of diaphragmatic contraction and dry cough, especially under conscious sedation. This prospective study presents a method to minimize the impact of PFA on diaphragmatic contraction and dry cough during the procedure. METHODS AND RESULTS: Twenty-eight patients underwent PFA for pulmonary vein (PV) and superior vena cava isolation under conscious sedation. Each patient received two groups of ablations in each vein: the control group allowed PFA application during any phase of respiratory cycle, while the test group used respiratory control, delivering PFA energy only at the end of expiration. A rating score system was developed to assess diaphragmatic contraction and dry cough. A total of 1401 control ablations and 4317 test ablations were performed. The test group had significantly lower scores for diaphragmatic contraction (P < 0.01) and dry cough (P < 0.001) in all PVs compared to the control group. The average relative reductions in scores for all PVs were 33-47% for diaphragmatic contraction and 67-83% for dry cough. The percentage of ablations with scores ≧2 for diaphragmatic contraction decreased significantly from 18.5-28.0% in the control group to 0.4-2.6% in the test group (P < 0.001). For dry cough, the percentage decreased from 11.9-43.7% in the control group to 0.7-2.1% in the test group. CONCLUSION: Pulsed-field ablation application at the end of expiration can reduce the severity of diaphragmatic contraction and eliminate moderate and severe dry cough during PV isolation performed under conscious sedation.

The effectiveness and feasibility of using multi-lead ECG monitoring combined with a programmed intracavitary ECG to complete left bundle branch area pacing.

BACKGROUND: Left bundle branch area pacing (LBBaP) as an alternative method for delivering physiological pacing, is difficult for many primary hospitals that lack the electrophysiological multichannel recorder to carry out. We hope to find a simple and feasible method that combines the multi-lead surface electrocardiogram (ECG) monitoring and the intracavity ECG of the pacing programmer to achieve LBBaP. METHODS: A total of 50 patients with bradycardia indications who attempted permanent pacemaker implantation were included in this study. We referred to multi-lead surface ECG monitoring and pacing system analyzer (PSA), combined with the nine-zone pacing method of the LBBaP, to complete LBBaP. We assessed multiple parameters to verify whether the LBBaP was successfully achieved and used univariable analysis of variance for repeated measures to judge the feasibility and effectiveness of LBBaP without the electrophysiological multichannel recorder. RESULTS: LBBaP was successfully archived without the electrophysiological multichannel recorder in 44 of 50 patients (88%). In the study, paced QRS duration and the stimulus to peak left ventricular activation time (Sti-LVAT) were 117.04 ± 10.34 ms and 71.10 ± 7.91 ms and had no significant changes in the 3-month follow-up. The unipolar pacing threshold and R-wave amplitudes were 0.85 ± 0.32 V and 10.36 ± 5.24 mV at baseline respectively, which also showed stability during the 1-month and 3-month follow-up. During the 3-month follow-up, no lead-related complication was recorded. CONCLUSION: It is effective and feasible to achieve LBBaP combining the multi-lead ECG monitoring and the intracavitary ECG of PSA without the electrophysiological multichannel recorder, which could be an alternative to perform LBBaP.

The specific value of upgrading to left bundle branch area pacing in patients with pacing-induced cardiomyopathy or non-pacing-induced cardiomyopathy related upgrade status: A retrospective study.

AIMS: Left bundle branch area pacing (LBBaP) upgrade can improve cardiac function and clinical outcomes in patients with pacing-induced cardiomyopathy (PICM), but the specific value of LBBaP upgrade, especially compared with the cardiac function level before right ventricular pacing (RVP) in patients with PICM and non-pacing-induced cardiomyopathy-related upgrade status (Non-PICMUS) is still unknown. METHODS: This study retrospectively enrolled 70 patients with LBBaP upgrade (38 patients with PICM and 32 patients with Non-PICMUS). All upgrade patients experienced three stages: before RVP (Pre-RVP), before LBBaP upgrade (Pre-LBBaP), and after LBBaP upgrade (Post-LBBaP). QRS duration (QRSd), lead parameters, echocardiographic indicators, and clinical outcomes evaluation were recorded at multiple time points. RESULTS: At the follow-up of 12 months, for PICM patients, left ventricular ejection fraction (LVEF) significantly increased from 36.6% ± 7.2% to 51.3% ± 8.7% Post-LBBaP (p < .001), and left ventricular end-diastolic diameter (LVEDD) significantly decreased from 61.5 ± 6.4 mm to 55.2 ± 6.5 mm Post-LBBaP (p < .001), but they both failed to restore the level Pre-RVP (both p < .001). For PICM patients, New York Heart Association (NYHA) classification, the number of moderate-to-severe heart failure (NYHA III-IV), and diuretics using rate after the LBBaP upgrade also could not restore to the level Pre-RVP (all p < .001). At the follow-up of 12 months, Non-PICMUS patients after the LBBaP upgrade had no significant improvement in LVEF, LVEDD, and NYHA classification (all p > .05). CONCLUSION: LBBaP upgrade effectively improved the cardiac function and clinical outcomes in PICM patients, but its effectiveness seemed to be limited as the deteriorated cardiac function cannot be completely reversed. For Non-PICMUS patients, the cardiac function and clinical outcomes Post-LBBaP had no significant improvement.

Intracardiac echocardiography is a safe and effective alternative to transesophageal echocardiography for left atrial appendage thrombus evaluation at the time of atrial fibrillation ablation: The ICE-TEE study.

BACKGROUND: Intracardiac echocardiography (ICE) technology has been increasingly accepted as an integral part of atrial fibrillation (AF) ablation procedures. It is still unknown whether ICE can routinely replace transesophageal echocardiography (TEE) for routine thrombus screening in non-selective AF patients. OBJECTIVE: To assess whether ICE can routinely replace TEE in screening for left atrial (LA)/left atrial appendage (LAA) thrombus in general patients undergoing catheter ablation for AF. METHODS: A total of 2003 consecutive patients undergoing AF ablation were included. 1155 patients (ICE group) received intra-procedural ICE examination for LA/LAA thrombus screening, while 848 patients (TEE group) received pre-procedure TEE examination. The incidence of thrombus, peri-procedure complications, and hospital efficiency were assessed. RESULTS: The LA and LAA were adequately visualized in all patients. Five patients in the ICE group and 15 patients in the TEE group were found to have LAA thrombus. The incidence of major periprocedural thrombo-embolic events was comparable between two groups (0.2% vs. 0.1%, p = .76), none were due to undetected LA/LAA thrombus. Other major periprocedural complications occurred at similar rates in both groups, while post-procedure fever was less common in the ICE group (12.7% vs. 17.4%, p < .001). Procedure times and hospital length of stay were both shorter in the ICE group (142 min [87-197 min] vs. 150 min [95-205 min], and 3[2-4] day vs. 4[3-5] day, respectively, both p < .001). CONCLUSIONS: ICE can replace TEE for atrial thrombus screening in AF patients undergoing ablation without increased complications. An "ICE replacing TEE" workflow can also reduce the incidence of postoperative fever and improve hospital efficiency.

Catheter ablation for persistent atrial fibrillation with left ventricular systolic dysfunction: Who is the best candidate?

BACKGROUND: Tachycardia-induced cardiomyopathy is poorly recognized pre-ablation. It remains unclear of better patient selection and timing for catheter ablation in persistent atrial fibrillation (PerAF) with heart failure (HF). METHODS: Consecutive patients with PerAF and left ventricular ejection fraction (LVEF) <50% referred for AF ablation were retrospectively included. The impact of LV size, heart rate (HR), and LVEF pre-ablation were analyzed for assessing LV systolic function recovery, defined as LVEF increase of ≥20% or to a value ≥55% after ablation. RESULTS: A total of 120 patients (2017-2020) were included. After 19 ±14 months post ablation, LVEF improvement was similar in patients with normal or dilated LV (18.3 ± 9.4% vs. 16.1 ± 10.8%, P = .25), rapid or controlled HR (19.5 ± 10% vs. 16.1 ± 10%, P = .09), but higher in HFrEF (HF with reduced EF) than HFmrEF (HF with midrange EF) (21.6 ± 10.3% vs. 14.9 ± 9.3%, P < .01). There was more LV systolic function recovery in those with normal to moderate LV dilation (80%, odds ratio [OR] 15.22, P < .01), HR ≥80 bpm (79%, OR 5.38, P < .01) and HFmrEF (80%, OR 4.03, P < .01). The overall AF freedom was similar between normal and dilated LV (59% vs. 62%, P = .95), rapid and controlled HR (67% vs. 56%, P = .18), and HFmrEF and HFrEF (65% vs. 50%, P = .19). CONCLUSION: Catheter ablation is effective independent of LV dilation, rate control or HFrEF. Patients with normal to moderate LV dilation, resting HR ≥80 bpm and HFmrEF may be candidates for early PerAF ablation to achieve LVEF normalization.

Preliminary experience of permanent left bundle branch area pacing using stylet-directed pacing lead without delivery sheath.

BACKGROUND: Left bundle branch area pacing (LBBAP) aims to capture the cardiac conduction system in area of the left bundle branch. Currently, LBBAP is mainly performed using lumen-less pacing leads (LLLs) with preshaped sheath. However, the data on LBBAP with stylet-driven leads (SDLs) without sheath is limited. OBJECTIVE: This study presents the feasibility, safety, and pacing characteristics of LBBAP using SDLs without the support of sheath. METHODS: A total of 25 patients with bradycardia indications who received LBBAP implantation with an attempt of SDL (FINELINE II 4471 lead, Boston Scientific, MA, US) between August 2020 and April 2021 at Sir Run Run Shaw Hospital were included in this retrospective cohort study. Twenty of them finally were paced with SDL in priority (SDL-LBBAP group). Twenty propensity score matching patients who underwent LBBAP with LLL (Select Secure 3830 lead, Medtronic, MN, US) and 20 right ventricular septal pacing (RVSP) with regular active fixation lead respectively in the same period (the LLL-LBBAP group and RVSP group) were compared using ECG characteristics, pacing parameters and complications during 6-month follow-up. RESULTS: LBBAP was successful with SDL in 23 of 25 patients (92%) and 20 of them were paced with SDL first. In the SDL-LBBAP group, the average age was 70.4 ± 8.2 years, and 55% of patients were male. Paced QRS duration and the stimulus to peak left ventricular activation time (Sti-LVAT) in SDL-LBBAP group were similar with those in LLL-LBBAP group and significantly shorter than those in RVSP group (126.1±14.1 ms vs. 124.8±10.9 ms, p = 1.00; 77.7 ± 11.2 ms vs. 73.5 ± 9.3 ms, P = .75; 126.1 ± 14.1 ms vs. 147.7 ± 22.5 ms, P<.001; 77.7 ± 11.2 ms vs. 97.0 ± 13.2 ms, P<.001). The pacing threshold and R-wave amplitude of SDL-LBBAP group were 0.53 ± 0.18V and 11.53 ± 3.63 mV at baseline respectively, which were comparable with the other two groups. During the 6-month follow-up, the pacing parameters remained stable and no lead-related complications were recorded. CONCLUSION: It is feasible and safe to use stylet-directed pacing lead for permanent LBBAP without a delivery sheath. Similar to LLL, LBBAP using SDL showed stable parameters and narrower paced QRS duration compared with RVSP, which could be an alternative to LLL in LBBAP.

Patient-Specific and Gene-Corrected Induced Pluripotent Stem Cell-Derived Cardiomyocytes Elucidate Single-Cell Phenotype of Short QT Syndrome.

RATIONALE: Short QT syndrome (SQT) is a rare but arrhythmogenic disorder featured by shortened ventricular repolarization and a propensity toward life-threatening ventricular arrhythmias and sudden cardiac death. OBJECTIVE: This study aimed to investigate the single-cell mechanism of SQT using patient-specific and gene-corrected induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). METHODS AND RESULTS: One SQT patient carrying missense mutation T618I in potassium voltage-gated channel subfamily H member 2 ( KCNH2) was recruited as well as 2 healthy control subjects in this study. Control and SQT patient-specific iPSCs were generated from skin fibroblasts using nonintegrated Sendai virus. The KCNH2 T618I mutation was corrected by genome editing in SQT iPSC lines to generate isogenic controls. All iPSCs were differentiated into iPSC-CMs using monolayer-based differentiation protocol. SQT iPSC-CMs exhibited abnormal action potential phenotype featured by shortened action potential duration and increased beat-beat interval variability, when compared with control and gene-corrected iPSC-CMs. Furthermore, SQT iPSC-CMs showed KCNH2 gain-of-function with increased rapid delayed rectifying potassium current (IKr) density and enhanced membrane expression. Gene expression profiling of iPSC-CMs exhibited a differential cardiac ion-channel gene expression profile of SQT. Moreover, QTc of SQT patient and action potential durations of SQT iPSC-CMs were both normalized by quinidine, indicating that quinidine is beneficial to KCNH2 T618I of SQT. Importantly, shortened action potential duration phenotype observed in SQT iPSC-CMs was effectively rescued by a short-peptide scorpion toxin BmKKx2 with a mechanism of targeting KCNH2. CONCLUSIONS: We demonstrate that patient-specific and gene-corrected iPSC-CMs are able to recapitulate single-cell phenotype of SQT, which is caused by the gain-of-function mutation KCNH2 T618I. These findings will help elucidate the mechanisms underlying SQT and discover therapeutic drugs for treating the disease by using peptide toxins as lead compounds.

Modelling high performance potassium-ion battery anode materials with two-dimensional vanadium carbide MXene: the role of surface O- and S-terminations.

Due to the low cost, high element abundance and intrinsic safety, potassium-ion batteries (KIBs) have attracted a surge of interest in recent years. Currently, the key challenge and obstacle to the development of KIBs is to find suitable anode materials with large capacity, high rate capability and small lattice changes during the charge/discharge process. MXenes with excellent energy storage properties are promising anode materials for KIBs and their energy performance largely depends on the surface termination. Here, two-dimensional O- and S-terminated V2C MXene anode materials are designed to model high performance potassium-ion batteries. Using first-principles calculations, the structural properties and potential battery performance in KIBs of V2CO2 and V2CS2 are systematically investigated. The inherent metallic nature, a small diffusion barrier, a low average open circuit voltage, and a high theoretical specific capacity (489.93 mA h g-1 of V2CO2 and 200.24 mA h g-1 of V2CS2) demonstrate that both of them are ideal anode materials for KIBs. Meanwhile, we also investigated the mechanism of the difference in energy performance between V2CO2 and V2CS2 at atomic and electronic levels, in other words, the energy performance difference introduced by surface O- and S-terminations.

Comparison of synchronization between left bundle branch and his bundle pacing in atrial fibrillation patients: An intra-patient-controlled study.

BACKGROUND: His bundle pacing (HBP) is a physiological pacing strategy to preserve the electrical synchrony of ventricular conduction and left ventricular (LV) function. Left bundle branch pacing (LBBP) has emerged as an alternative physiological pacing technique. OBJECTIVE: To evaluate cardiac electrical and mechanical synchrony comparing LBBP and HBP in patients with permanent atrial fibrillation (AF). METHODS: Consecutive patients with symptomatic bradycardia and AF were enrolled from January to June of 2019. The cardiac electrical and mechanical synchrony in different pacing mode were evaluated at baseline and after implantation. RESULTS: Both HBP and LBBP were performed in 20 patients. LBBP significantly widened the QRS duration compared with the intrinsic conduction (113.2 ± 14.5  vs. 96.5 ± 16.2 ms; p = .01), while HBP did not (104.5 ± 22.3  vs. 96.5 ± 16.2 ms; p = .12). Both LBBP and HBP patients had similar LV myocardial strain measurements for the mechanical synchrony evaluation without significant change compared with baseline. There was no significant difference in right ventricular synchrony measurement between LBBP and HBP. Compared to HBP, LBBP had less interventricular synchrony (IMVD, 14.7 ± 9.2  vs. 3.1 ± 12.7 ms, p < .01; Ts-LV-RV, 37.9 ± 10.7  vs. 18.5 ± 10.8 ms, p < .001). CONCLUSIONS: Although LBBP's a physiological pacing mode can achieve a similar cardiac electrical and mechanical synchronization when compared to HBP, LBBP results in modest delay in RV activation, and the clinical implication remains to be studied.

Adjunctive percutaneous ablation targeting epicardial arrhythmogenic structures in patients of atrial fibrillation with recurrence after multiple procedures.

INTRODUCTION: Repeat ablation strategy for atrial fibrillation (AF) recurrence after multiple ablation procedures is known to be challenging. This study evaluated the insights of adjunctive ablation for epicardial arrhythmogenic substrates in those patients via a percutaneous epicardial approach. METHODS AND RESULTS: Thirty-five consecutive patients with AF/atrial tachycardia (AT) recurrence, who had two or more prior ablation procedures, were enrolled from September 2016 to December 2018. In addition to a standard endocardial approach, epicardial mapping and ablation were performed via a percutaneous subxiphoid access in the electrophysiology lab. Adjunctive epicardial ablations for left lateral ridge (LLR) were performed in 31 of 35 patients (88.6%) for efficient transmural lesions with pacing capture loss. Marshall Bundle (MB) potentials were documented on epicardial LLR in three patients and abolished by direct epicardial ablation. Bachmann's bundle (BB) was ablated as an epicardial conduction gap in four patients with a refractory anterior wall line. Two epicardial AT/AF triggers were detected followed by successful termination with epicardial ablation. No periprocedural complications occurred. About 23 of 35 patients (65.7%) remained free from AF/AT after 23.2 ± 9 months of the procedure. CONCLUSIONS: Patients with multiple failed prior AF procedures refractory to antiarrhythmic therapy might warrant a percutaneous epicardial mapping and ablation strategy, with adjunctive therapy for targeting LLR/MB, BB, and underlying epicardial triggers in addition to a standard endocardial approach.

Intraprocedural endpoints to predict durable pulmonary vein isolation: a randomized trial of four post-ablation techniques.

AIMS: The optimal procedural endpoint to achieve permanent pulmonary vein isolation (PVI) during ablation of atrial fibrillation (AF) remains unknown. We aimed to compare the impact of prolonged waiting periods and adenosine triphosphate (ATP) testing after PVI on long-term freedom from AF. METHODS AND RESULTS: In total, 538 patients (median age 61 years, 62% male) undergoing first-time radiofrequency ablation for paroxysmal AF were randomized into four groups: Group 1 [PVI (no testing), n = 121], Group 2 (PVI + 30min waiting phase, n = 151), Group 3 (PVI+ATP, n = 131), and Group 4 (PVI + 30min+ATP, n = 135). The primary endpoint was freedom from AF. Repeat mapping to assess for late pulmonary vein (PV) reconnection was performed in patients who remained AF-free for >3 years (n = 46) and in those who had repeat ablation for AF recurrence (n = 82). During initial procedure, acute PV reconnection was observed in 33%, 26%, and 42% of patients in Groups 2, 3, and 4, respectively. At 36 months, no significant differences in freedom from AF recurrence were observed among all four groups (55%, 61%, 50%, and 62% for Groups 1, 2, 3, and 4, respectively; P = 0.258). Late PV reconnection was commonly observed, with a similar incidence between patients with and without AF recurrence (74% vs. 83%; P = 0.224). CONCLUSION: Although PVI remains the cornerstone for AF ablation, intraprocedural techniques to assess for PV reconnection did not improve long-term success. Patients without AF recurrence after 3 years exhibited similarly high rates of PV reconnection as those that underwent repeat ablation for AF recurrence. The therapeutic mechanisms of AF ablation may not be solely predicated upon durable PVI.

Risk of esophageal thermal injury during catheter ablation for atrial fibrillation guided by different ablation index.

BACKGROUND: During ablation for atrial fibrillation (AF), energy delivery toward the left atrial posterior wall may cause esophageal injury (EI). Ablation index (AI) was introduced to estimate ablation lesion size, however, the impact of AI technology on the risk of EI has not been explored. METHOD: From March 2019 to December 2019, 60 patients with paroxysmal AF undergoing first-time ablation were prospectively enrolled. The first 30 consecutive patients were ablated with the AI target value of 400 (AI-400 group), and the later 30 consecutive patients were ablated with the AI target value of 350 at the posterior wall (AI-350 group). Endoscopic ultrasonography was used to evaluate EI postablation. EI was classified as a category 1 (erythema or erosion) or a category 2 (hematoma or ulceration). RESULTS: Compared with the AI-400 group (59.9 ± 8.4 years; male, 60%), the AI-350 group (59.1 ± 9.9 years; male, 50%) had a lower incidence of EI (3.3% vs 26.7%, P = .03). There was no significant difference in the percentage of first-pass PVI between the AI-400 group and the AI-350 group (left PVI: 80% vs 73.4%, P = .54; right PVI: 80% vs 60%, P = .1). Neither ablation time nor fluoroscopy time was significantly different between the AI-400 group and the AI-350 group. CONCLUSIONS: AF ablation guide by AI target value of 350 may reduce esophageal thermal injury and has a similar efficiency on the acute success rate of first-pass PVI compared with an AI target value of 400 at the posterior wall.

Esophageal contraction during cryoablation: A possible protective mechanism.

BACKGROUND: Contraction of the esophagus was observed during cryoablation for paroxysmal atrial fibrillation (PAF). The purpose of this study is to investigate the mechanism of esophageal contraction and the correlation between the contraction and esophageal thermal lesions. METHODS: This prospective study enrolled 64 patients with PAF undergoing second-generation cryoballoon (CB2) ablation for pulmonary vein isolation (PVI). During PVI for the left inferior pulmonary vein, contrast esophagography was performed before and during cryoablation. The sample population was divided into two groups: A (31 patients) and B (33 patients). Group A consisted of patients in whom the distal half of the CB was in proximity to the esophagus, while for group B the esophagus was away from the distal half of the CB. Esophageal contraction was recorded as a variation in the width of the esophageal lumen during PVI. Postablation esophageal endoscopy was done on all patients. RESULTS: The reduction in the width of the esophageal lumen in group A was greater than in group B during freezing (40.12 ± 23.24% vs 8.14 ± 10.35%, P < .001). Following endoscopy, no apparent esophageal lesion was detected in all patients. CONCLUSION: The extent of esophageal contraction is correlated with the positioning of the esophagus at the distal half of the CB. The findings of this study indicate that esophageal contraction during freezing may be a self-protective mechanism.

Implantable cardioverter defibrillator replacement guided by T wave safety margin in a short QT syndrome patient.

We report implantable cardioverter defibrillator (ICD) generator replacement guided by T wave safety margin (TWSM) in a short QT syndrome patient with T wave oversensing (TWOS). During the procedure of generator replacement, the feature of ventricular sensing in four different ICDs was compared in the patient. The four ICDs showed different R and T wave amplitudes. Though R/T ratio is not the highest, Vitality ICD showed the highest TWSM and was implanted as replacing generator. During 20-month follow-up, the patient has been symptom-free with no T-wave oversensing episode. This case illustrates a method to evaluate the risk of TWOS before ICD implantation in patients with high risk of TWOS.

Impact of Anatomically Guided Ganglionated Plexus Ablation on Electrical Firing from Isolated Pulmonary Veins.

BACKGROUND: The mechanisms underlying atrial fibrillation (AF) initiation and pulmonary vein isolation (PVI) effectiveness remain unclear. Ganglionated plexus (GPs) have been implicated in AF initiation and maintenance. In this study, we evaluated the impact of GP ablation in patients with pulmonary vein (PV) firing after PVI. METHODS: Patients with drug-refractory paroxysmal AF undergoing radiofrequency catheter ablation therapy with PVI were screened. Among 840 cases over a 3.75-year period, 12 cases were identified with persistent PV firing (left = 4 and right = 8) after PVI was achieved and left atrial sinus rhythm restored. Adjacent GP ablation was performed anatomically and followed if necessary by additional PV ablation. RESULTS: In eight patients, PV firing was terminated during GP ablation outside of the circumferential ablation line. In one patient, additional PV ablation resulted in cessation of PV firing and in the remaining three patients, firing could not be terminated by GP ablation or additional PVI. CONCLUSION: GP ablation outside of wide antral circumferential line frequently results in the cessation of rapid firing from electrically isolated PVs. These observations suggest that interactions between left atrium and PV beyond electrical conduction warrant consideration in AF mechanisms.

Marked suppression of pulmonary vein firing after circumferential pulmonary vein isolation in patients with paroxysmal atrial fibrillation: is pulmonary vein firing an epiphenomenon?

INTRODUCTION: Rapid firing in pulmonary veins (PVs) is a leading cause of paroxysmal atrial fibrillation. We hypothesized that PV firing (PV-F) should continue after circumferential PV isolation (CPVI) because the PV tissue responsible for PV-F remains intact. METHODS AND RESULTS: In Group-1 (n = 92), isoproterenol (ISP) and adenosine triphosphate (ATP) were co-administered to provoke PV-F before and after CPVI. The site of rapid focal discharge that initiated atrial fibrillation (AF) defined PV-F versus non-PV-F. Additional 17 patients with PV-F induced by ISP+ATP before CPVI were enrolled into Group-2 and various pacing maneuvers were used in conjunction to ISP+ATP to provoke PV-F after CPVI. In Group-1, AF was induced in 47/81 (58.0%) and 16/88 (18.2%) patients before and after CPVI, respectively (P < 0.01). Before CPVI, 43/47 (91.5%) of the rapid firing originated from PV. After successful CPVI, 88/92 patients were in sinus rhythm and non-PV-F was induced in 14/88 patients. PV-F was induced in 2/88 patients, which was eliminated by ganglionated plexus ablation outside the CPVI line. In Group-2, various pacing maneuvers with ISP+ATP only induced PV-F in 1/17 patients after CPVI. CONCLUSION: Marked suppression of PV-F after CPVI strongly suggests that the real source of PV-F is located in the atrium. PV-F may be an epiphenomenon.

Ti3C2 mediates the NiFe-LDH layered electrocatalyst to enhance the OER performance for water splitting.

Oxygen evolution reaction (OER) is a very complex process with slow reaction kinetics and high overpotential, which is the main limitation for the commercial application of water splitting. Thus, it is of necessary to design high-performance OER catalysts. NiFe based layered double hydroxides (NiFe-LDHs) have recently gained a lot of attention due to their high reaction activity and simple manufacturing process. In this study, a novel electrocatalyst based on NiFe-LDH was constructed by introducing Ti3C2, which was utilized to modulate the structural and electronic properties of the electrocatalysts. Structural examinations reveal that the Ti3C2 of 2D structure successfully dope the NiFe-LDHs nanosheets, forming NiFe-LDH/Ti3C2 heterojunctions. Firstly, the heterojunction substantially reduces the charge transfer resistance, promoting the electron migration between the LDH nanosheets. Secondly, theoretical calculations demonstrate that the energy barrier between the rate-determining step from *OH to *O is lowered, favoring the formation of the reaction intermediates and thus the occurrence of OER. As a result, the composite electrocatalyst exhibits a low overpotential of 334 mV at a current density of 10 mA/cm2 and a small Tafel slope of 55 mV/dec, which are superior to those of the NiFe-LDH by 11.2 % and 38.5 %, respectively. This study provides inspiration for promoting the performances of NiFe based electrocatalysts by utilizing 2D materials.

Two-Dimensional SnS Mediates NiFe-LDH-Layered Electrocatalyst toward Boosting OER Activity for Water Splitting.

NiFe-layered double hydroxides (NiFe-LDHs), as promising electrocatalysts, have received significant research attention for hydrogen and oxygen generation through water splitting. However, the slow oxidation kinetics of NiFe-LDH, due to the limited number of active sites and the low conductivity, hinders the improvement of the water-splitting efficiency. Therefore, to overcome the obstacles, two-dimensional (2D) SnS was first explored to tailor the prepared NiFe-LDH via the hydrothermal method. A NiFe-LDH/SnS heterojunction is built, which is observed from the microstructural investigations. SnS incorporation could greatly improve the conductivity of the NiFe-LDH sheets, which was reflected by the reduced charge transfer resistance. Moreover, SnS layers modulated the electronic environment around the active sites, favoring the adsorption of intermediates during the oxygen evolution reaction (OER) process, which was verified by density functional theory calculations. A synergistic effect induced by the NiFe-LDH/SnS heterostructure promoted the OER activities in electrical, electronic, and energetic aspects. Consequently, the as-prepared NiFe-LDH/SnS electrocatalyst greatly improved the electrocatalytic performance, exhibiting 20% and 27% reductions in the overpotential and Tafel slope compared with those of pristine NiFe-LDH, respectively. The results provide a strategy for regulating NiFe-based electrocatalysts by using emerging 2D materials to enhance water-splitting efficiency.

Use of intracardiac echocardiography in vein of Marshall ethanol infusion for ablation of persistent atrial fibrillation.

BACKGROUND: Few methods have been reported to demonstrate real-time effects during vein of Marshall (VOM) ethanol infusion in persistent atrial fibrillation (PeAF). OBJECTIVE: This study was to evaluate the impact of left atrial (LA) monitoring using intracardiac echocardiography (ICE) during VOM ethanol infusion. METHODS: Seventy-four consecutive patients with PeAF who underwent VOM ethanol infusion followed by radiofrequency (RF) ablation were included. Patients with findings on ICE consistent with echogenic streaming in the LA and with increased myocardial local echogenicity along the VOM area were placed into one group (group A) and those without into the other group (group B). Outcomes between the 2 groups were compared. RESULTS: Forty-six patients (62%) were placed into group A. A new ethanol-induced low-voltage area in group A was larger than that in group B (8.5 cm2 [5.5-10.2 cm2] and 4.0 cm2 (2.4-6.3 cm2]; P < .001). The RF ablation time required to achieve MI block was reduced in group A patients (263.0 seconds [196.0-351.0 seconds] vs 417.0 seconds [315.0-709.5 seconds] in group B patients; P < .001). MI block was achieved in 46 patients (100%) via an endocardial approach in group A and 27 patients (96.4%) in group B (extra coronary sinus ablation in 4 patients). One patient developed clinically significant pericardial effusions and required pericardiocentesis in group B. CONCLUSION: Presence of increased myocardial local echogenicity at the ridge and consistent echogenic streaming in the LA detected by ICE-based imaging during VOM ethanol infusion suggests increased ablated tissue in that region and lower RF ablation time during ablation for PeAF.