Effects of low-density lipoprotein cholesterol on sleep apnea: Insights from a rat model of cardiovascular autonomic dysregulation.

INTRODUCTION: The levels of low-density lipoprotein (LDL) cholesterol in plasma are important risk factors for coronary heart disease. Several reports suggest that elevated plasma cholesterol is associated with cardiac arrhythmias. In a subsequent study investigating LDL cholesterol levels and the frequency of LDL cholesterol measurements, a positive correlation was observed between the severity of sleep apnea and visit-to-visit LDL cholesterol variability. Our objective was to assess the effects of hypercholesterolemia on cardiac autonomic activity, disordered sleep patterns, and increased incidence of arrhythmias in freely moving rats. METHODS: Wireless transmission of polysomnographic recordings was performed in control and high cholesterol male rats during normal daytime sleep. Spectral analyses were conducted on the electroencephalogram and electromyogram (EMG) recordings to distinguish active waking, quiet sleep, and paradoxical sleep. Heart rate variability power spectrum analysis was used to measure cardiac autonomic activity. RESULTS: The high cholesterol group exhibited a higher low-frequency (LF)/high-frequency (HF) power ratio during all sleep stages compared to the control group. Additionally, the frequency of sleep interruptions was increased in the high cholesterol group compared to the control group. CONCLUSIONS: Our results show significant sleep fragmentation with sympathetic hyperactivity after exposure to high cholesterol. This indicates that high cholesterol may increase the risk of sleep apnea and poor sleep quality by disrupting autonomic homeostasis.

Factors predicting the progression from paroxysmal to persistent atrial fibrillation despite an index catheter ablation.

INTRODUCTION: Despite undergoing an index ablation, some patients progress from paroxysmal atrial fibrillation (PAF) to persistent AF (PersAF), and the mechanism behind this is unclear. The aim of this study was to investigate the predictors of progression to PersAF after catheter ablation in patients with PAF. METHODS: This study included 400 PAF patients who underwent an index ablation between 2015 and 2019. The patients were classified into three groups based on their outcomes: Group 1 (PAF to sinus rhythm, n = 226), Group 2 (PAF to PAF, n = 146), and Group 3 (PAF to PersAF, n = 28). Baseline and procedural characteristics were collected, and predictors for AF recurrence and progression were evaluated. RESULTS: The mean age of the patients was 58.4 ± 11.1 years, with 272 males. After 3 years of follow-up, 7% of the PAF cases recurred and progressed to PersAF despite undergoing an index catheter ablation. In the multivariable analysis, a larger left atrial (LA) diameter and the presence of non-pulmonary vein (PV) triggers during the index procedure independently predicted recurrence. Moreover, a larger LA diameter, the presence of non-PV triggers, and a history of thyroid disease independently predicted AF progression. CONCLUSION: The progression from PAF to PersAF after catheter ablation is associated with a larger LA diameter, history of thyroid disease, and the presence of non-PV triggers. Meticulous preprocedural evaluation, patient selection, and comprehensive provocation tests during catheter ablation are recommended.

Neural mechanism facilitating PM2.5-related cardiac arrhythmias through cardiovascular autonomic and calcium dysregulation in a rat model.

Particulate matter < 2.5 µm (PM2.5) exposure is associated with increased arrhythmia events and cardiovascular mortality, but the detailed mechanism remained elusive. In the current study, we aimed to investigate the autonomic alterations in a rodent model after acute exposure to PM2.5. Twelve male WKY rats were randomized to control and PM2.5 groups. All were treated with 2 exposures of oropharyngeal aerosol inhalations (1 µg PM2.5 per gram of body weight in 100 µL normal saline for the PM2.5 group) separately by 7 days. Polysomnography and electrocardiography were surgically installed 7 days before oropharyngeal inhalation and monitored for 7 days after each inhalation. Physiologic monitors were used to define active waking (AW), quiet sleep (QS), and paradoxical sleep (PS). Autonomic regulations were measured by heart rate variability (HRV). The protein expression of ventricular tissue of the 2 groups was compared at the end of the experiment. In sleep pattern analysis, QS interruption of the PM2.5 group was significantly higher than the control group (0.52 ± 0.13 events/min, 0.35 ± 0.10 events/min, p = 0.002). In HRV analysis, the LF/HF was significantly higher for the PM2.5 group than the control group (1.15 ± 0.16, 0.64± 0.30, p = 0.003), largely driven by LF/HF increase during the QS phase. Ionic channel protein expression from Western blots showed that the PM2.5 group had significantly lower L-type calcium channel and higher SERCA2 and rectifier potassium channel expressions than the control group, respectively. Our results showed that acute PM2.5 exposure leads to interruption of QS, sympathetic activation, and recruitment of compensatory calcium handling proteins. The autonomic and calcium dysregulations developed after PM 2.5 exposure may explain the risk of sleep disturbance and sleep-related arrhythmia.

Renal denervation reverses ventricular structural and functional remodeling in failing rabbit hearts.

Renal denervation (RDN) suppresses the activity of the renin-angiotensin-aldosterone system and inflammatory cytokines, leading to the prevention of cardiac remodeling. Limited studies have reported the effects of renal denervation on ventricular electrophysiology. We aimed to use optical mapping to evaluate the effect of RDN on ventricular structural and electrical remodeling in a tachycardia-induced cardiomyopathy rabbit model. Eighteen rabbits were randomized into 4 groups: sham control group (n = 5), renal denervation group receiving RDN (n = 5), heart failure group receiving rapid ventricular pacing for 1 month (n = 4), and RDN-heart failure group (n = 4). Rabbit hearts were harvested for optical mapping. Different cycle lengths were paced (400, 300, 250, 200, and 150 ms), and the results were analyzed. In optical mapping, the heart failure group had a significantly slower epicardial ventricular conduction velocity than the other three groups. The RDN-heart failure, sham control, and RDN groups had similar velocities. We then analyzed the 80% action potential duration at different pacing cycle lengths, which showed a shorter action potential duration as cycle length decreased (P for trend < 0.01), which was consistent across all groups. The heart failure group had a significantly longer action potential duration than the sham control and RDN groups. Action potential duration was shorter in the RDN-heart failure group than the heart failure group (P < 0.05). Reduction of conduction velocity and prolongation of action potential duration are significant hallmarks of heart failure, and RDN reverses these remodeling processes.

Comparison of efficacy of pulmonary vein isolation between cryoballoon ablation and high-power short-duration ablation.

BACKGROUND: High-power short-duration (HPSD) and cryoballoon ablation (CBA) has been used for pulmonary vein isolation (PVI). OBJECTIVE: We aimed to compare the efficacy of PVI between CBA and HPSD ablation in patients with paroxysmal atrial fibrillation (PAF). METHODS: We retrospectively analyzed 251 consecutive PAF patients from January 2018 to July 2020. Of them, 124 patients (mean age 57.2 ± 10.1 year) received HPSD and 127 patients (mean age 59.6 ± 9.4 year) received CBA. In HPSD group, the radiofrequency energy was set as 50 W/10 s at anterior wall and 40 W/10 s at posterior wall. In CBA group, 28 mm s generation cryoballoon was used for PVI according the guidelines. RESULTS: There was no significant difference in baseline characteristics between these 2 groups. The time to achieve PVI was significantly shorter in cryoballoon ablation group than in HPSD group (20.6 ± 1.7 min vs 51.8 ± 36.3, P = 0.001). The 6-month overall recurrence for atrial tachyarrhythmias was not significantly different between the two groups (HPSD:14.50% vs CBA:11.0%, P = 0.40). There were different types of recurrent atrial tachyarrhythmia between these 2 groups. Recurrence as atrial flutter was significantly more common in CBA group compared to HPSD group (57.1% vs 12.5%, P = 0.04). CONCLUSION: In PAF patients, CBA and HPSD had a favourable and comparable outcome. The recurrence pattern was different between CBA and HPSD groups.

Abnormal Conduction Zone Detected by Isochronal Late Activation Mapping Accurately Identifies the Potential Atrial Substrate and Predicts the Atrial Fibrillation Ablation Outcome After Pulmonary Vein Isolation.

BACKGROUND: The presence of abnormal substrate of left atrium is a predictor of atrial fibrillation (AF) recurrence after pulmonary vein isolation. We aimed to investigate the isochronal late activation mapping to access the abnormal conduction velocity for predicting AF ablation outcome. METHODS: Forty-five paroxysmal AF patients (30 males, 57.8±8.7 years old) who underwent pulmonary vein isolation were enrolled. Isochronal late activation mapping was retrospectively constructed with 2 different windows of interest: from onset of P wave to onset of QRS wave on surface electrocardiography (W1) and 74 ms tracking back from the end of P wave (W2). Deceleration zone was defined as regions with 3 isochrones (DZa) or ≥4 isochrones (DZb) within a 1 cm radius on the isochronal late activation mapping, and the estimated conduction velocity (ECV) are 0.27 m/s and <0.20 m/s for DZa and DZb, respectively in W2. The distribution of deceleration zone was compared with the location of low-voltage zone (bipolar voltage ≤0.5 mV). Any recurrence of atrial arrhythmias was defined as the primary end point during follow ups after a 3-month blanking period. RESULTS: Pulmonary vein isolation was performed in all patients, and there were 2 patients (4.4%) received additional extrapulmonary vein ablation. After a mean follow-up of 12.7±4.5 months, recurrence of AF occurred in 14 patients (31.1%). Patients with the presence of DZb in W2 had higher AF recurrence (Kaplan-Meier event rate estimates: HR, 9.41 [95% CI, 2.61-33.90]; log-rank P<0.0001). There were 52.6% of the DZb locations in W2 comparable to the distributions of low-voltage zone and 47.4% DZb were distributed in the area without low-voltage zone. CONCLUSIONS: Deceleration zone detected by isochronal late activation mapping represents a critical AF substrate, it accurately predicts the AF recurrence following ablation in patients with paroxysmal AF.

Post-ablation augmentation of skin sympathetic nerve activity predicts a poor outcome of idiopathic ventricular arrhythmias.

BACKGROUND: The neuromodulation effect after ventricular arrhythmia (VA) ablation is unclear. The study aimed to investigate skin sympathetic nerve activity (SKNA) changes in patients receiving catheter ablations for idiopathic VA. METHODS: Of 43 patients with drug-refractory symptomatic VA receiving ablation, SKNA was continuously recorded for 10 min during resting from electrocardiogram lead I configuration and bipolar electrodes on the right arm 1 day before and 1 day after ablation. RESULTS: Twenty-two patients with acute procedure success and no recurrence during follow-ups were classified as sustained success group (group 1). Other 21 patients were classified as failed ablation group (group 2). Baseline SKNA showed no significant difference between the two groups. Post-ablation SKNA in group 2 was significantly higher than in group 1. In patients with ablation involved right ventricular outflow tract (RVOT), the post-ablation SKNA was also significantly higher in group 2. In contrast, there was no difference in post-ablation SKNA between groups in patients receiving non-RVOT ablation. CONCLUSION: The neuromodulation response after RVOT ablation may correspond to the sympathetic nerve distribution at RVOT. Augmentation of sympathetic activity after VA ablation indicates an unsuccessful VA suppression, especially in patients receiving ablation of RVOT VA.

Impact of Amiodarone Therapy on the Ablation Outcome of Ventricular Tachycardia in Arrhythmogenic Right Ventricular Cardiomyopathy.

(1) Background: Catheter ablation (CA) is an accepted treatment option for drug-refractory ventricular tachycardia (VT) in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). This study investigates the effect of amiodarone on ablation outcomes in ARVC. (2) Methods: The study enrolled patients with ARVC undergoing CA of sustained VT. In all patients, substrate modification was performed to achieve non-inducible VT. The patients were categorized into two groups according to whether they had used amiodarone before CA. Baseline and electrophysiological characteristics, substrate, and outcomes were compared. (3) Results: A total of 72 ARVC patients were studied, including 29 (40.3%) "off" amiodarone and 43 (56.7%) "on" amiodarone. The scar area was similar between the two groups. Patients "off" amiodarone had smaller endocardial and epicardial areas with abnormal electrograms. Twenty of 43 patients (47.5%) "on" amiodarone discontinued it within 3 months after CA. During a mean follow-up period of 43.2 ± 29.5 months, higher VT recurrence was observed in patients "on" amiodarone. Patients "on" amiodarone who discontinued amiodarone after CA had a lower recurrence than those without. (4) Conclusions: Patients with ARVC "on" amiodarone before CA had distinct substrate characteristics and worse ablation outcomes than patients "off" amiodarone, especially in those who had used amiodarone continuously.

Electrophysiological characteristics of epicardial breakthrough during catheter ablation of perimitral atrial flutter.

Introduction: Unsuccessful endocardial ablation for perimitral atrial flutter (AFL) could be attributed by the epicardial bridging. Objective: This study aimed to investigate the electrophysiological characteristics of epicardial breakthrough during catheter ablation of perimitral AFL. Materials and methods: This retrospective study recruited 40 patients who received successful catheter ablation of perimitral AFL from January 2016 to June 2021. The patients were divided into two groups: group 1 (n = 18) successful endocardial ablation, and group 2 (n = 22) successful epicardial ablation following unsuccessful endocardial ablation owing to incomplete mitral block or unachievable termination AFL. The local electrogram (EGM) interval of coronary sinus (CS) duration perimitral AFL was measured before catheter ablation. Results: There was no significant difference in the baseline characteristics between the two groups. In group 2, 60% of successful epicardial ablation was performed in intra-CS ablation and 40% in VOM ethanol infusion. Group 2 patients had a longer EGM interval of distal CS than that in group 1 (CS1-2: 64.2 17.5 vs. 42.4 0.09 ms, P = 0.008, CS3-4: 57.13 19.4 vs. 43.8 7.5 ms; P = 0.001). The conduction velocity at successful site was slower in group 2 compared to group 1 (0.18 0.05 vs. 0.75 0.19 m/s, P = 0.040). In the multivariate analysis, distal EGM interval (CS1-2) was identified as independent predictor of the need of epicardial ablation with the optimal cutoff of 49 ms. Conclusion: Longer EGM interval in distal CS during perimitral AFL was observed in perimitral AFL patients with epicardial breakthrough following endocardial-failed ablation, which may be associated with the need of epicardial ablation.

10-Year Outcomes of Patients With Non-Paroxysmal Atrial Fibrillation Undergoing Catheter Ablation.

BACKGROUND: Radiofrequency catheter ablation (RFCA) is commonly performed in patients with non-paroxysmal atrial fibrillation (AF), but because very long-term follow-up results of RFCA are limited, we investigated the 10-year RFCA outcomes of non-paroxysmal AF.Methods and Results: We retrospectively enrolled 100 patients (89 men, mean age 53.5±8.4years) with drug-refractory symptomatic non-paroxysmal AF who underwent 3D electroanatomic-guided RFCA. Procedural characteristics at index procedures and clinical outcomes were investigated. In the index procedures, all patients had pulmonary vein isolation, 56 (56.0%), 48 (48.0%), and 32 (32.0%) underwent additional linear, complex fractionated atrial electrogram (CFAE) and non-pulmonary vein (NPV) foci ablations, respectively. After 124.1±31.7 months, 16 (16%) patients remained in sinus rhythm after just 1 procedure (3 with antiarrhythmic drugs [AAD]) and after multiple (2.1±1.3) procedures in 53 (53.0%) patients (22 with AAD). Left atrial (LA) diameter (hazard ratio HR 1.061; 95% confidence interval (CI) 1.020 to 1.103; P=0.003), presence of NPV triggers (HR 1.634; 95% CI 1.019 to 2.623; P=0.042) and undergoing CFAE ablation (HR 2.003; 95% CI 1.262 to 3.180; P=0.003) in the index procedure were independent predictors for recurrent atrial tachyarrhythmia. CONCLUSIONS: The 10-year outcomes of single RFCA in non-paroxysmal AF were unsatisfactory. Enlarged LA, presence of NPV triggers, and undergoing CFAE ablation in the index procedure independently predicted single-procedure recurrence. Multiple procedures are required to achieve adequate rhythm control.

Alteration of Skin Sympathetic Nerve Activity after Pulmonary Vein Isolation in Patients with Paroxysmal Atrial Fibrillation.

Autonomic system plays a pivotal role in the pathogenesis of paroxysmal atrial fibrillation (AF). Skin sympathetic nerve activity (SKNA) is a noninvasive tool for assessing sympathetic tone. However, data on changes in SKNA after ablation are limited. Here, we retrospectively enrolled 37 patients with symptomatic drug-refractory paroxysmal AF who underwent pulmonary vein isolation (PVI) with radiofrequency ablation (RFA) or cryoablation (CBA). SKNA was measured from the chest and right arm 1 day prior to ablation, as well as 1 day and 3 months after ablation. One day after ablation, the SKNA-Arm increased from 517.1 µV (first and third quartiles, 396.0 and 728.0, respectively) to 1226.2 µV (first and third quartiles, 555.2 and 2281.0), with an increase of 179.8% (125% and 376.0%) (p < 0.001); the SKNA-Chest increased from 538.2 µV (first and third quartiles, 432.9 and 663.9) to 640.0 µV (first and third quartiles, 474.2 and 925.6), with an increase of 108.3% (95.6% and 167.9%) (p = 0.004), respectively. In those without recurrence, there was a significant increase in SKNA 1 day after ablation as compared with those before ablation. Twelve patients received SKNA measurement 3 months after ablation; both SKNA-Arm (p = 0.31) and SKNA-Chest (p = 0.27) were similar to those before ablation, respectively. Among patients with symptomatic drug-refractory paroxysmal AF receiving PVI, increased SKNA was observed 1 day after ablation and returned to the baseline 3 months after ablation. Elevation of SKNA was associated with lower early and late recurrences following ablation.

Patterns and Characteristics of SKYLINE-Lumipoint Feature in the Catheter Ablation of Atypical Atrial Flutter: Insight from a Novel Lumipoint Module of Rhythmia Mapping System.

Background: Atypical atrial flutter (aAFL) is not uncommon, especially after a prior cardiac surgery or extensive ablation in atrial fibrillation (AF). Aims: To revisit aAFL, we used a novel Lumipoint algorithm in the Rhythmia mapping system to evaluate tachycardia circuit by the patterns of global activation histogram (GAH, SKYLINE) in assisting aAFL ablation. Methods: Fifteen patients presenting with 20 different incessant aAFL, including two naïve, six with a prior AF ablation, and seven with prior cardiac surgery were studied. Results: Reentry aAFL in SKYLINE typically was a multi-deflected peak with 1.5 GAH-valleys. Valleys were sharp and narrow-based. Most reentry aAFL (18/20, 90%) lacked a plateau and displayed a steep GAH-valley with 2 GAH-valleys per tachycardia. Each GAH-valley highlighted 1.9 areas in the map. Successful sites of ablation all matched one of the highlighted areas based on GAH-valleys < 0.4. These sites corresponded with the areas highlighted by GAH-score < 0.4 in reentry aAFL, and by GAH-score < 0.2 in localized-reentry aAFL. Conclusions: The present study showed benefits of the LumipointTM module applied to the RhythmiaTM mapping system. The results were the efficient detection of the slow conduction, better identification of ablation sites, and fast termination of the aAFL with favorable outcomes.

Sinus Node Dysfunction after Successful Atrial Flutter Ablation during Follow-Up: Clinical Characteristics and Predictors.

Identification of sinus node dysfunction (SND) before termination of persistent AFL by catheter ablation (CA) is challenging. This study aimed to investigate the characteristics and predictors of acute and delayed SND after AFL ablation. We retrospectively enrolled 221 patients undergoing CA of persistent AFL in a tertiary referral center. Patients with SND who required a temporary pacemaker (TPM) after termination of AFL or a permanent pacemaker (PPM) during follow-up were identified. Acute SND requiring a TPM was found in 14 of 221 (6.3%) patients following successful termination of AFL. A total of 10 of the 14 patients (71.4%) recovered from acute SND. An additional 11 (5%) patients presenting with delayed SND required a PPM during follow-up, including 4 patients recovering from acute SND. Of these, 9 of these 11 patients (81.8%) underwent PPM implantation within 1 year after the ablation. In multivariable analysis, female gender and a history of hypothyroidism were associated with the requirement for a TPM following termination of persistent AFL, while older age and a history of hypothyroidism predicted PPM implantation. This study concluded that the majority of patients with acute SND still require a PPM implantation despite the initial improvement. Therefore, it is reasonable to monitor the patients closely for at least one year after AFL ablation.

Percutaneous Left Atrial Appendage Closure Using an Occluder Device: A Single Center Experience.

Background: Left atrial appendage (LAA) is the main source of thrombus formation, and occlusion of this structure decreases the risk of stroke in patients with atrial fibrillation. Objectives: We aimed to describe the feasibility, safety and outcomes of percutaneous LAA closure using an occluder device, and to evaluate residual LAA contrast leak detected on computed tomography (CT) imaging in patients who underwent implantation in our institution. Methods: Consecutive patients of Taipei Veterans General Hospital who underwent percutaneous implantation of an LAA occluder (LAAO) were retrospectively collected and analyzed. Results: A total of 23 patients were included with a median age of 67 years (42-87) and median CHA2DS2-VASc score of 4 (1-7). The most frequent indication for intervention was bleeding while on oral anticoagulation treatment. After a mean follow-up of 31.17 ± 25.10 months, successful device implantation was achieved in 95.7% of the patients. There was no occurrence of death, stroke, device embolization, acute ST elevation myocardial infarction, major bleeding requiring invasive treatment or blood transfusion, inguinal hematoma or major bleeding related to antiplatelet therapy. One patient had cardiac tamponade, 1 had intra-procedural thrombus formation, 1 had impingement of mitral valve leaflet, and 1 had device-related thrombosis. Of 12 patients who underwent CT post- implantation, 6 had residual contrast leak into the LAA, one third of those who had peri-device leak. Conclusions: Percutaneous implantation of an LAAO appeared to be feasible with a low risk of major complications.

Application of dynamic display technology to identify gaps after pulmonary vein isolation in catheter ablation of atrial fibrillation.

BACKGROUND: The identification of post pulmonary vein isolation (PVI) gaps by activation and voltage maps is time-consuming. This study aimed to investigate the characteristics, efficiency and accuracy of LiveView dynamic display module (EnSite™ Dynamic Display; Abbott, Abbott Park, IL, USA) in unmasking post PVI gaps and conduction block line. METHOD: Twenty four patients with paroxysmal atrial fibrillation (PAF) who failed to achieve first-pass PVI or with recurrent PAF were enrolled. Ninety-six pulmonary veins (PVs) were evaluated, and gaps were identified in 25 (26.0%) PVs. The gap location was confirmed by activation and propagation maps; 110 frames on gaps and 118 frames on block lines were analyzed by using LiveView module. We defined isochronal crowding in the local activation time (LAT) mode as three colors between two adjacent electrodes. Each frame was classified as with or without isochronal crowding in LAT mode and one/continuous color or isochronal discontinuity in reentrant mode. The gray color inside the PVs was considered to represent conduction block. RESULT: The isochronal crowding could be found on both gap and block line in LAT mode, whereas isochronal discontinuity only presented on the block line in reentrant mode. The sensitivity and specificity of isochronal discontinuity or gray color in reentrant mode to identify block line were 61.0% and 100%, respectively. The sensitivity and specificity of isochronal crowding or gray color in LAT mode to identify block line were 71.2% and 71.8%, respectively. CONCLUSION: Reentrant mode in LiveView module is very specific in identifying block lines. We proposed an efficient, practical algorithm to differentiate the block line from PV gaps.

Application of Ensite™ LiveView function for identification of scar-related ventricular tachycardia isthmus.

INTRODUCTION: Dynamic display of real-time wavefront activation pattern may facilitate the recognition of reentrant circuits, particularly the diastolic path of ventricular tachycardia (VT). OBJECTIVE: We aimed to evaluate the feasibility of LiveView Dynamic Display for mapping the critical isthmus of scar-related reentrant VT. METHODS: Patients with mappable scar-related reentrant VT were selected. The characteristics of the underlying substrates and VT circuits were assessed using HD grid multielectrode catheter. The VT isthmuses were identified based on the activation map, entrainment, and ablation results. The accuracy of the LiveView findings in detecting potential VT isthmus was assessed. RESULTS: We studied 18 scar-related reentrant VTs in 10 patients (median age: 59.5 years, 100% male) including 6 and 4 patients with ischemic and nonischemic cardiomyopathy, respectively. The median VT cycle length was 426 ms (interquartile range: 386-466 ms). Among 590 regional mapping displays, 92.0% of the VT isthmus sites were identified by LiveView Dynamic Display. The accuracy of LiveView for isthmus identification was 84%, with positive and negative predictive values of 54.8% and 97.8%, respectively. The area with abnormal electrograms was negatively correlated with the accuracy of LiveView Dynamic Display (r = -.506, p = .027). The median time interval to identify a VT isthmus using LiveView was significantly shorter than that using conventional activation maps (50.5 [29.8-120] vs. 219 [157.5-400.8] s, p = .015). CONCLUSION: This study demonstrated the feasibility of LiveView Dynamic Display in identifying the critical isthmus of scar-related VT with modest accuracy.

Effects of renal denervation on sleep apnea and arrhythmia in rats with myocardial infarction.

BACKGROUND: Sympathetic hyperactivity and poor sleep quality have been reported in patients with myocardial infarction (MI). Sleep is an important modulator of cardiovascular function. We aimed to evaluate the effects of renal denervation (RDN) on cardiac autonomic activity and disordered sleep patterns in rats with MI. METHODS: Wireless transmission of polysomnographic recordings was performed in sham and left coronary artery (LCA) ligation male rats during normal daytime sleep before and after RDN. Spectral analyses of electroencephalogram and electromyogram (EMG) recordings were performed to define active waking, quiet sleep, and paradoxical sleep. Cardiac autonomic activity was measured by analyzing the power spectrum of heart rate variability. Central sleep apnea events were measured by analyzing the EMG recordings of the diaphragm. RESULTS: In the LCA ligation group, there was a higher low-frequency (LF)/high-frequency (HF) power ratio during sleep; the LF/HF ratio decreased significantly in the rats that underwent RDN in all sleep stages when compared with that in the rats that did not. The frequency of sleep interruptions increased without RDN in the LCA ligation group when compared with that in the sham group. This change was ameliorated and prevented with RDN in the LCA ligation group. CONCLUSIONS: Our results demonstrate significant sleep fragmentation with sympathetic hyperactivity after MI and that RDN prevents autonomic dysfunction and disordered sleep. RDN may then reduce sleep apnea and sleep-related sudden cardiac death after MI by restoring autonomic homeostasis.

Renal artery denervation prevents ventricular arrhythmias in long QT rabbit models.

Long QT syndrome (LQTS) is commonly presented with life-threatening ventricular arrhythmias (VA). Renal artery denervation (RDN) is an alternative antiadrenergic treatment that attenuates sympathetic activity. We aimed to evaluate the efficacy of RDN on preventing VAs in LQTS rabbits induced by drugs. The subtypes of LQTS were induced by infusion of HMR-1556 for LQTS type 1 (LQT1), erythromycin for LQTS type 2 (LQT2), and veratridine for LQTS type 3 (LQT3). Forty-four rabbits were randomized into the LQT1, LQT2, LQT3, LQT1-RDN, LQT2-RDN, and LQT3-RDN groups. All rabbits underwent cardiac electrophysiology studies. The QTc interval of the LQT2-RDN group was significantly shorter than those in the LQT2 group (650.08 ± 472.67 vs. 401.78 ± 42.91 ms, p = 0.011). The QTc interval of the LQT3-RDN group was significantly shorter than those in the LQT3 group (372.00 ± 22.41 vs. 335.70 ± 28.21 ms, p = 0.035). The VA inducibility in all subtypes of the LQT-RDN groups was significantly lower than those in the LQT-RDN groups, respectively (LQT1: 9.00 ± 3.30 vs. 47.44 ± 4.21%, p < 0.001; LQT2: 11.43 ± 6.37 vs. 45.38 ± 5.29%, p = 0.026; LQT3: 10.00 ± 6.32 vs. 32.40 ± 7.19%, p = 0.006). This study demonstrated the neuromodulation of RDN leading to electrical remodeling and reduced VA inducibility of the ventricular substrate in LQT models.

Copper migration and isotope fractionation in a typical paddy soil profile of the Yangtze Delta.

To decipher Cu migration in paddy soils, which is important for understanding Cu supply in rice cultivation, Cu concentrations and isotope compositions were measured in a paddy soil profile in Suzhou, Eastern China, in the central Yangtze Delta. The results show that the variations in δ65Cu values and Cu concentrations are not coupled along the profile. From top to bottom, the δ65Cu values show small variations (0.07 ± 0.03‰ to 0.25 ± 0.01‰) in the upper layers (Ap-Br1), with a decrease in the subsurface Br2 layer (from 0.16 ± 0.04‰ to -0.19 ± 0.02‰), are almost homogeneous in the transitional Br3-BCrg layers (-0.01 ± 0.01‰ to -0.10 ± 0.02‰), and further decrease to -0.33 ± 0.01‰ in the permanently submerged G1 and G2 layers. Copper concentrations in the Ap layer show some fluctuations (25.8 to 29.0 µg/g), increase in the Br2 and Br3 layers (23.9 µg/g to 31.9 µg/g), and then decrease to 15.1 µg/g in the lower layers. The lack of coupling between δ65Cu values and Cu concentrations may be ascribed to various physicochemical conditions in different layers. In the upper layers, Cu(I) enriched in light isotopes migrates downward with soil solutions under flooded conditions, leaving the soils of the Ap and Br1 layers enriched in heavy Cu isotopes. In the Br2 layer, the readsorption of light Cu isotopes on clay minerals results in decreased δ65Cu values and increased Cu concentrations. In the Br3-BCrg layers, Cu(I) can be oxidized to Cu(II). The homogeneous Cu isotopes in these layers may mainly result from equilibrium adsorption of Cu on clay minerals. The decreased δ65Cu values and Cu concentrations in the G layer are mainly attributed to groundwater transport in this layer. This study represents the Cu isotope variations in a paddy soil profile and the possible mechanism of Cu isotope fractionation.