Softened Microstructure and Properties of 12 µm Thick Rolled Copper Foil.

Up to now, 12 µm thick rolled copper foil is the thinnest rolled copper foil that can be stably produced. The softened microstructure and properties of 12 µm thick rolled copper foil were systematically studied in this paper. The softened process consists of thermal treatment at 180 °C for different times. The results show that the softened annealing texture is mainly cubic texture, and the cubic texture fraction increases with the increase in annealing time. The cubic texture fraction reaches the highest (34.4%) after annealing for 60 min. After annealing for 1-5 min, the tensile strength and the bending times decrease significantly. After annealing for 10-60 min, the tensile strength tends to be stable, and the bending times increase slightly. With the increase in annealing time, the electrical conductivity increases gradually, reaching 92% International Annealed Copper Standard (IACS) after annealing for 60 min. Electrical conductivity can be used as a fast and effective method to analyze the microstructure of metals.

Characteristics and Long-Term Ablation Outcomes of Supraventricular Arrhythmias in Hypertrophic Cardiomyopathy: A 10-Year, Single-Center Experience.

Background: A variety of supraventricular arrhythmias (SVAs) may occur in patients with hypertrophic cardiomyopathy (HCM). The characteristics and long-term ablation outcomes of different types of SVAs in HCM have not been comprehensively investigated. Methods: We retrospectively enrolled 101 consecutive patients with HCM who were referred to the electrophysiology and arrhythmia service from May 2010 to October 2020. The clinical features and ablation outcomes were analyzed. Results: Seventy-eight patients had SVAs, which comprised 50 (64.1%) cases of atrial fibrillation (AF), 16 (20.5%) of atrial flutter (AFL), 15 (19.2%) of atrioventricular reentrant tachycardia (AVRT), 11 (14.1%) of atrial arrhythmia (AT), and 3 (3.8%) of atrioventricular nodal reentrant tachycardia (AVNRT). Thirty-four patients underwent catheter ablation and were followed up for a median (interquartile range) of 58.5 (82.9) months. There was no recurrence in patients with non-AF SVAs. In patients with AF, the 1- and 7-year AF-free survival rates were 87.5 and 49.5%, respectively. A receiver operator characteristic analysis showed that a greater left ventricular end-diastolic dimension (LVEDD) was associated with a higher recurrence of AF, with an optimum cutoff value of 47 mm (c-statistic = 0.91, p = 0.011, sensitivity = 1.00, specificity = 0.82). In Kaplan-Meier analysis, patients with a LVEDD ≥ 47 mm had worse AF-free survival than those with a LVEDD <47 mm (log-rank p = 0.014). Conclusions: In this unique population of HCM, AF was the most common SVA, followed in order by AFL, AVRT, AT, and AVNRT. The long-term catheter ablation outcome for non-AF SVAs in HCM is satisfactory. A greater LVEDD predicts AF recurrence after catheter ablation in patients with HCM.

The incidence and location of epicardial connections in the era of contact force guided ablation for pulmonary vein isolation.

BACKGROUND: The effects of epicardial connections (ECs) involving pulmonary veins (PVs) in atrial fibrillation (AF) ablation have been revealed recently. However, no systematic approaches to identify and ablate the ECs were established. METHODS: Patients with AF undergoing radiofrequency (RF) catheter ablation were retrospectively analyzed. ECs were identified when (1) PV isolation (PVI) cannot be achieved after first-pass isolation; (2) PVI was still absent although the conduction gap was detected and ablated; (3) the earliest activation area (EAA) was revealed located within the PV antrum distant from the initial ablation line using high-density mapping (HDM) technique; (4) focal ablation at the EAA was effective to achieve PVI. Relevant pacing maneuvers were performed to elucidate ECs' bidirectional conduction. RESULTS: Overall, 36 ECs were identified and ablated in 35/597 (5.86%) patients. Among the 35 patients with ECs, at least one PV insertion of ECs was located at the carina region. The most common pattern was a single breakthrough in 31 (88.6%) patients, followed by multiple breakthroughs in 3 and wide breakthroughs in 1. The median distance from EAA to the initial ablation line was 10.0 mm. The average number of RF energy delivery was 1.75 ± 1.00, and single RF delivery was adequate in 16/36 (44.4%) patients. Continuous potentials were present at the EAA in 9/34 (26.5%) patients. CONCLUSION: ECs were confirmed and ablated successfully in 5.86% (35/597) AF patients using HDM. PV insertions of ECs were mainly located at the carina region. Continuous potentials might assist in the prediction of ECs.

Efficiency, Safety, and Efficacy of High-Power Short-Duration Radiofrequency Ablation in Patients with Atrial Fibrillation.

Pulmonary vein isolation (PVI) is the cornerstone therapy of atrial fibrillation (AF). Radiofrequency catheter ablation (RFCA) is performed using a point-by-point method to achieve durable PVI. However, this procedure remains complex and time-consuming, and the long-term clinical outcomes are still not satisfactory. Recently, there has been increasing interest in the clinical application of high-power short-duration (HPSD) approaches in the field of RFCA. HPSD ablation, distinguishing it from the conventional ablation strategy, delivers RF energy at a high power and saves the dwell time at each site. It is unknown whether the HPSD approach can bring some gratifying changes in the field of RF energy ablation. A number of experimental studies and clinical studies have been conducted regarding this topic. The review aimed to summarize the research findings and evaluate the procedural efficiency, safety, and clinical outcomes of the HPSD approach based on the evidence available to date.

Idiopathic Ventricular Arrhythmias Ablated in Different Subregions of the Aortic Sinuses of Valsalva: Anatomical Distribution, Precordial Electrocardiographic Notch Patterns, and Bipolar Electrographic Characteristics.

Background: Little is known about the differences among ventricular arrhythmias (VAs) ablated in different subregions of the aortic sinuses of Valsalva (ASVs). We aim to investigate the distribution, precordial electrocardiographic patterns, and bipolar electrogram characteristics of VAs ablated in different subregions of the ASVs. Methods: We divided the right ASV and the left ASV into a total of 6 subregions and studied 51 idiopathic VAs ablated first time successfully in the ASVs. Results: These 51 VAs were inhomogeneously distributed among the 6 subregions, which comprised the right-lateral ASV (1/51), the right-anterior ASV (11/51), the regions along the right (13/51) and left (9/51) sides of the ASV junction, the left-anterior ASV (5/51), and the left-lateral ASV (12/51). Fractionated potentials were dominant (39/51, 76%) among the 3 types of target electrograms. From the right-lateral ASV to the left-lateral ASV, the percentage of fractionated potentials gradually decreased from 100 to 59%. A precordial rebound notch in V3-V4 or V4-V5 had sensitivity of 90.9%, specificity of 85.0%, and negative predictive value (NPV) of 97.1% to predict VAs ablated in the right-anterior ASV. A precordial rebound notch in V2-V3 had sensitivity of 50.0%, specificity of 94.9%, and NPV of 86.0% to predict VAs ablated in the left-lateral ASV. Conclusion: VA targets were mainly distributed in the anterior and the left-lateral ASVs. Fractionated potentials were common among target electrograms, especially in theright-anterolateral ASV. Precordial electrocardiographic rebound notch has high predictive accuracy in identifying different subregions of the ASVs as target ablation sites.

Predictive value of unipolar and bipolar electrograms in idiopathic outflow tract ventricular arrhythmia mapping and ablation.

INTRODUCTION: Radiofrequency catheter ablation is an effective therapy for focal idiopathic outflow tract ventricular arrhythmia (OTVA). However, visual inspection of the unipolar electrogram (EGM) QS morphology is subjective with a poor specificity for predicting successful ablation sites. This study aims to evaluate the predictive value of unipolar and bipolar EGMs in OTVA mapping and ablation. METHODS AND RESULTS: Twenty-two patients scheduled for idiopathic OTVA ablation were prospectively enrolled. During the procedure, unipolar and bipolar EGMs were recorded simultaneously and visually inspected by the operator to identify their values for predicting arrhythmogenic sites. Quantitative features of the unipolar EGM including the ratio of amplitude of the first positive peak versus the nadir (R-ratio), the maximum descending slope (MaxSlope), and the time interval between the initial deflection point to the MaxSlope (D-Max) were calculated for each target site in offline analysis. EGMs from 100 sites were collected in 20 patients and analyzed. The bipolar reverse polarity characteristic was not as practical for identifying successful ablation site as the unipolar QS characteristic. Successful ablation sites demonstrated smaller R-ratio and shorter D-Max than unsuccessful sites, but no significant difference in MaxSlope. A unipolar EGM-derived quantitative criterion provided significantly better specificity (0.70) than visual inspection (0.37) without compromising on the sensitivity (0.83 vs. 0.89). CONCLUSION: The bipolar reverse polarity characteristic was not a practical method for identifying target in idiopathic OTVA ablation. The unipolar EGM-derived quantitative criteria have better predictive performance than visual inspection of the QS characteristic and are likely to reduce unnecessary ablation sites.

Transoesophageal echocardiography prior to catheter ablation could be avoided in atrial fibrillation patients with a low risk of stroke and without filling defects in the late-phase MDCT scan: A retrospective analysis of 783 patients.

OBJECTIVES: To test whether multidetector computed tomography (MDCT) could completely replace transoesophageal echocardiography (TEE) to detect left atrial appendage (LAA) thrombi in atrial fibrillation (AF) patients using a large sample size. METHODS: 783 patients with AF who underwent MDCT and TEE before catheter ablation were retrospectively included. Demographic data were obtained. Two radiologists blinded to clinical data made the imaging diagnosis. RESULTS: Most of the patients (96.2 %) had a CHA2DS2-VASc score (congestive heart failure, hypertension, age ≥ 75 years old (doubled), diabetes, stroke/transient ischaemic attack/thromboembolism (doubled), vascular disease, age 65-74 years, female sex) ≤ 3. Eight thrombi were identified by TEE, all of which were detected by MDCT; no thrombus was observed with TEE without the observation of filling defects by late-phase MDCT scanning in any of the patients. Using TEE as reference standard, the sensitivity, specificity, positive predictive value and negative predictive value of MDCT for thrombus detection were 100 %, 95.74 % (95 % CI 94.33 %-97.15 %), 19.51 % (95 % CI 16.73 %-22.29 %) and 100 %, respectively. CONCLUSIONS: For AF patients with low risk of stroke, when MDCT images showed no filling defect in the late phase, TEE prior to catheter ablation can be avoided. KEY POINTS: • MDCT can help detect the presence of LAA thrombus. • TEE can be avoided when late-phase MDCT shows no filling defect. • TEE is required in patients whose MDCT images indicate thrombus.

Prediction of ventricular arrhythmia events in ischemic heart disease patients with implantable cardioverter-defibrillators.

The aim of the study was to exam the prediction of ventricular arrhythmia events in ischemic heart disease patients with implantable cardioverter-defibrillators (ICD). A total of 123 consecutive patients confirmed ischemia heart disease with ICD were examined. After device implantation, the occurrence of appropriate ICD therapy was noted. Patients were divided into two groups according to the ventricular arrhythmia occurrence. Patients with ventricular arrhythmia occurrence had a significantly great incidence of atrial fibrillation history compare to the no-ventricular arrhythmia occurrence group (8 vs. 39%, P = 0.02). The level of high-sensitive C-reactive protein (hsCRP) baseline was also significantly higher in the ventricular arrhythmia group than in the no ventricular arrhythmia (3.78 ± 1.1 vs. 0.94 ± 0.7, P < 0.01). The taking of ß blocker is not common in ventricular arrhythmia group patients than no ventricular arrhythmia group (5 vs. 29%, P = 0.03). By univariate comparison, male sex, the history of atrial fibrillation, and a high level of hsCRP were significant predictors for ventricular arrhythmia occurrence. By multivariate analysis, the atrial fibrillation burden, and had a high level of hsCRP were significant for incidence of ventricular arrhythmia occurrence in ischemic heart disease patients. ß-block were more likely to be free from ventricular arrhythmia occurrence. The high level of hsCRP, and the atrial fibrillation burden were strong predictor of ventricular arrhythmia occurrence in secondary prevention ICD recipients with ischemic heart disease. Taking ß-blockers was free from ventricular arrhythmia occurrence.

Cardiac resynchronization therapy reduces T-wave alternans in patients with heart failure.

AIMS: T-wave alternans (TWA) represents myocardial instability. The present study was to determine the impact of cardiac resynchronization therapy (CRT) on TWA and left ventricular ejection fraction (LVEF) in heart failure patients. METHODS AND RESULTS: T-wave alternans was analysed using a spectral method in 27 CRT-ICD patients. Ambulatory device electrograms were collected and LVEF and New York Heart Association (NYHA) classification were assessed at baseline prior to CRT and 3 months following CRT. Patients were followed for 6 months to monitor cardiac events. Spectral TWA of device electrograms was measured during AAI and CRT pacing tests. Each pacing mode had the up-titration pacing rate from 90 to 105 b.p.m. with 90 s for each pacing rate. At baseline, 20 (76.9%) patients had TWA during AAI pacing tests and 13 (50%) during CRT pacing tests (P = 0.044 between two pacing modes). Following 3-month CRT, TWA was identified in 11 patients (45.8%) during AAI pacing tests (a 31.1% reduction from the baseline value, P = 0.023) and 7 patients (28%) during CRT pacing tests (a 22% reduction, P = 0.108). Six of seven patients who had cardiac events had TWA (three patients had arrhythmic events, two died of heart failure, one received heart transplant). Overall, LVEF improved from 27.3 ± 5.8 to 35.9 ± 10.5% (P < 0.001) and NYHA classification improved from 2.8 ± 0.6 to 1.6 ± 0.6 after 3-month CRT (P < 0.001). CONCLUSION: In heart failure patients who receive a CRT-ICD, CRT reduces TWA that is associated to cardiac events, suggesting that CRT promotes clinically significant reverse electrical and mechanical remodelling.

[An association of apolipoprotein B with pulse pressure in Chinese pedigrees with familial combined hyperlipidemia].

OBJECTIVE: To investigate the influencing factors of blood pressure phenotypes and the distribution of FDH in FCHL families. METHODS: Forty-two FCHL families with 435 members, 147 consanguine members and 90 members without consanguinity from Beijing area were studied. Eleven of the 42 FCHL families (26.2%) were identified as families with FDH syndrome. Stepwise regression analysis was used to analyze the association between the target variables and blood pressure phenotypes, such as systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and pulse pressure (PP), of the 237 FCHL members aged 30 to 60 years. RESULTS: The prevalence of dyslipidemic hypertension in the FCHL relatives was significantly higher than that in the spouses (29.9% versus 8.9%, P < 0.01), with an odds ratio of 3.37 (95% CI 1.44 to 8.14). In the FCHL families body mass index (BMI), age and blood sugar were independent contributors to SBP, DBP, and MAP, respectively (all P < 0.05). Age and apolipoprotein B (apoB) were important contributors to pulse pressure (both P < 0.05). CONCLUSIONS: BMI and glucose are significant contributors to different phenotypes of blood pressure. Moreover, apoB is a significant contributor to pulse pressure in FCHL families.