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In this paper, LixCa(1−x)Cu3Ti4O12 (LCCTO) solid solutions were successfully synthesized. XRD diagrams showed that dopant acceptor Li+ cations, in a concentration range of x = 0.01–0.10, were successfully merged into CCTO structure. It was found that doping with low concentrations of lithium (x < 0.05) inhibited grain growth during annealing; however, for x > 0.05, the grain growth process resumed. Permittivity and dielectric losses of obtained LCCTO ceramics were analyzed by the means of impedance spectroscopy in a frequency range from 10−1 to 106 Hz. It was revealed that acceptor doping with lithium at an appropriate concentration of x = 0.05 allowed to obtain ceramics with a permittivity level of ε′ = 3 × 104 and low dielectric losses tanδ < 0.1 at 1 kHz. Further addition of lithium in a concentration range of x = 0.075–0.10 led to a sharp decline in permittivity and an increase in dielectric losses. It was discovered that lithium addition to CCTO ceramics drastically decreased grain boundary resistivity from 115 MΩ·cm to 5–40 MΩ·cm at x = 0.01–0.10. Using Havriliak–Negami equation, the relaxation times for grain dipoles and grain boundary dipoles were found to be ranging from 0.8 × 10−6 to 1.7 × 10−6 s and from 0.4 × 10−4 to 7.1 × 10−4 s, respectively. The developed materials can be used in the manufacture of Multilayer Ceramic Capacitors (MLCC) as a dielectric.

In this work we have synthesized Ti3C2TX MXene powder and studied its structure. Composite electrochemical coatings (CECs) of Ni-Ti3C2TX MXene were obtained from a sulfate– chloride bath in the galvanostatic regime. The microstructure of CEC was researched using X-ray phase analysis and scanning electron microscopy methods. It has been established that a Ni–Ti3C2TX MXene CEC microhardness rises by about 1.80 times compared with electrolytic Ni without a dispersed phase. For corrosion research, different corrosive media is applied. The corrosion–electrochemical behavior of Ni–Ti3C2TX MXene CECs by the chronovoltamperometry method in 0.5 M H2SO4 solution has been investigated. Trials in 3.5% NaCl have shown that Ti3C2TX MXene inclusion into the matrix of the electrochemical Ni results in a decrease in the corrosion rate by 1.60–1.75 times. These effects are due to the addition of Ti3C2TX MXene into the nickel matrix and the formation of CECs with a strengthening fine-grained structure.

Aims Pacing remote from the latest electrically activated site (LEAS) in the left ventricle (LV) may diminish response to cardiac resynchronization therapy (CRT). We tested whether proximity of LV pacing site (LVPS) to LEAS, determined by non-invasive three-dimensional electrical activation mapping [electrocardiographic Imaging (ECGI)], increased likelihood of CRT response. Methods and results Consecutive CRT patients underwent ECGI and chest/heart computed tomography 6–24 months of post-implant. Latest electrically activated site and the distance to LVPS (dp) were assessed. Left ventricular end-systolic volume (LVESV) reduction of ≥15% at clinical follow-up defined response. Logistic regression probabilistically modelled non-response; variables included demographics, heart failure classification, left bundle branch block (LBBB), ischaemic heart disease (IHD), atrial fibrillation, QRS duration, baseline ejection fraction (EF) and LVESV, comorbidities, use of CRT optimization algorithm, angiotensin-converting enzyme inhibitor(ACE)/angiotensin-receptor blocker (ARB), beta-blocker, diuretics, and dp. Of 111 studied patients [64 ± 11 years, EF 28 ± 6%, implant duration 12 ± 5 months (mean ± SD), 98% had LBBB, 38% IHD], 67% responded at 10 ± 3 months post CRT-implant. Latest electrically activated sites were outside the mid-to-basal lateral segments in 35% of the patients. dp was 42 ± 23 mm [31 ± 14 mm for responders vs. 63 ± 24 mm non-responders (P < 0.001)]. Longer dp and the lack of use of CRT optimization algorithm were the only independent predictors of non-response [area under the curve (AUC) 0.906]. dp of 47 mm delineated responders and non-responders (AUC 0.931). Conclusion The distance between LV pacing site and latest electrical activation is a strong independent predictor for CRT response. Non-invasive electrical evaluation to characterize intrinsic activation and guide LV lead deployment may improve CRT efficacy.

New three-phase composites, destined for application as dielectrics in the manufacturing of passive elements of flexible electronics, and based on polymer (PVDF) matrix filled with powdered ceramics of the hollandite-like (KFTO(H)) structure (5.0; 7.5; 15; 30 vol.%) and carbon (MWCNT) additive (0.5; 1.0; 1.5 wt.% regarding the KFTO(H) amount), were obtained and studied by XRD, FTIR and SEM methods. Chemical composition and stoichiometric formula of the ceramic material synthesized by the sol-gel method were confirmed with the XRF analysis data. The influence of the ceramic and carbon fillers on the electrical properties of the obtained composites was investigated using impedance spectroscopy. The optimal combination of permittivity and dielectric loss values at 1 kHz (77.6 and 0.104, respectively) was found for the compositions containing K

In this work, polymer matrix composites with the compositions PTFE/KFTO(H) and PTFE/KFTO(H)@CB and with filler volume fractions of 2.5, 5.0, 7.5, 15, and 30% (without and with carbon modification at a content of 2.5 wt.% regarding ceramic material) were produced by calendering and hot pressing and studied using FTIR, SEM, and impedance spectroscopy methods. Ceramic filler (KFTO(H)) was synthesized using the sol–gel Pechini method. Its structure was investigated and confirmed by the XRD method with following Rietveld refinement. The carbon black (CB) modification of KFTO(H) was carried out through the calcination of a mixture of ceramic and carbon materials in an argon atmosphere. Afterwards, composites producing all the components’ structures weren’t destroyed according to the FTIR results. The effect of carbon additive at a content of 2.5 wt.% relating to ceramic filler in the system of polymer matrix composites was shown, with permittivity increasing up to ε’ = 28 with a simultaneous decrease in dielectric loss (tanδ < 0.1) at f = 103 Hz for composites of PTFE/KFTO(H)@CB (30 vol.%).

Polymer matrix composites based on ED-20 epoxy resin, hollandite K1.6(Ni0.8Ti7.2)O16 and carbon nanotubes with a variable content of 0.107; 0.213 and 0.425 vol.% were obtained for the first time. Initial components and composites produced were characterized by XRD, XRA, FTIR, SEM and Raman spectroscopy. The dielectric properties of composite materials were measured by impedance spectroscopy and determined by the volume ratio of the composite components, primarily by the concentration of CNTs. At a CNT content of 0.213 vol.% (before percolation threshold), the maximum synergistic effect of carbon and ceramic fillers on the dielectric properties of a composite based on the epoxy resin was found. Three-phase composites based on epoxy resin, with a maximum permittivity at a minimum dielectric loss tangent, are promising materials for elements of an electronic component base.

Polymer matrix composites based on ED-20 epoxy resin, hollandite K

AIMS Radiofrequency catheter ablation of atrial fibrillation (AF) is one of the most complex ablation procedures. Both patients and operators are exposed to scattered radiation. This study evaluated the safety and efficacy of intracardiac echo (ICE)-guided pulmonary vein isolation (PVI) without fluoroscopy. METHODS We retrospectively analyzed the data of 481 consecutive patients with paroxysmal AF undergoing radiofrequency PVI with the CARTO 3 system (Biosense Webster, Diamond Bar, CA, USA). ICE-guided PVI without fluoroscopy and without CT/MRI integration (Nonfluoro group) was performed for 245 patients, and conventional fluoroscopy-guided PVI (Fluoro group) was performed for 236 patients. The primary safety endpoint was the incidence of major adverse events. The primary efficacy endpoint was freedom from AF during follow-up. Secondary endpoints included procedure duration, fluoroscopy duration, and acute PVI rate. RESULTS Mean procedure times between groups were similar (108.8 ± 18.2 minutes in the Non-fluoro group vs 113.6 ± 26.8 minutes in the Fluoro group; P = not significant [NS]). Acute PVI was achieved in all patients, with mean radiofrequency application times of 43.4 ± 7.5 and 44.4 ± 10.7 minutes for the Nonfluoro and Fluoro groups, respectively (P = NS). The incidence of cardiac tamponade was 1.2% (3/245 patients) in the Nonfluoro group and 0.8% (2/236 patients) in the Fluoro group (P = NS). During 15.2 ± 4.1 months of follow-up, after a single procedure, AF recurrence was documented in 65 of 245 (26.5%) patients and 61 of 236 (25.8%) patients in the Nonfluoro and Fluoro groups, respectively (P = NS). CONCLUSIONS Nonfluoroscopic ICE-guided catheter ablation of AF without prior cardiac image integration or angiography is feasible and safe. PVI without fluoroscopy did not affect procedure duration or long-term efficacy.

Introduction The aim of this study was to assess the use of a novel noninvasive epicardial and endocardial electrophysiology system (NEEES) for mapping of ventricular arrhythmias. Methods Eight patients (2 females, mean age 50 ± 17 years) with ischemic (n = 3) and nonischemic (n = 5) cardiomyopathy and inducible ventricular arrhythmias during electrophysiology study were enrolled. Noninvasive mapping of ventricular arrhythmias was performed using the NEEES based on body-surface electrocardiograms and computed tomography imaging data. Arrhythmia patterns were analyzed using noninvasive phase mapping. Results Macro-reentrant VT circuits were observed in 3 ischemic and 1 nonischemic cardiomyopathy patient, respectively. In the remaining 4 patients, phase mapping revealed relatively stable rotor activity and multiple wavelets. Conclusions Noninvasive cardiac mapping was able to visualize the macro-reentrant circuits in patients with scar-related VT. In patients without myocardial scar only polymorphic VT or VF was inducible, and rotor activity and multiple wavelets were observed.

Objective: to examine relationship between anatomical changes of the left ventricle (LV), dynamics of velocity of its volume modification, and blood flows in the LV in patients with mitral regurgitation (MR) before and after surgical treatment. Materials and methods. We included into this study 58 patients with severe 3-4 degree MR (38 men, 20 women aged 24-69 [mean age 51±9] years) in sinus rhythm (96%) or atrial fibrillation (4%). The control group included 86 healthy volunteers, mean age 39±7 years. Transthoracic echocardiographic studies were performed in both groups by standard technique at rest using a high-quality echocardiograph Vivid E9, equipped with a 3.5-4.6 MHz multi frequency transducer (in patients before and after surgical repair - mitral valve [MV] replacement and MV reconstruction with annuloplasty ring). The analysis of files recorded was performed off-line by vector analysis technique including estimation of myocardial deformation velocities and dynamics of LV volume modification, construction of “flow-volume” diagram, calculation of the expended kinetic energy, and registration of intraventricular blood flows. Results. End diastolic volume (EDV), end systolic volume (ESV) and total stroke volume (TSV) (effective + retrograde) were significantly increased in patients with severe LV volume overload before surgery in comparison with the control group (p kin ) in patients with MR before surgery was several times higher in diastole than in systole. After MV replacement E kin in systole and diastole decreased becoming closer to normal values. MV replacement restored the pattern of LV filling from the left atrium, and the blood flow reached the LV apex virtually without energy loss. Conclusions. Thus, myocardial deformation velocities, LV blood flows allow to quantify cardiac function in patients with MV insufficiency and to assess the effectiveness of surgical treatment in the early and remote postoperative periods. Phenomenological patterns in evaluation of LV myocardial function and valve apparatus are based not only on anatomical changes of heart chambers, but also on the dynamics of myocardial deformation velocities, what allows to get closer to a assessment of global cardiac function, taking into consideration blood flow dynamics and turbulence in the ventricles, characterizing the cardiac performance and particularly the kinetic energy of the myocardium. Evaluation of stagnant areas in the LV based on the velocity of intracardiac blood flow, reconstructed from color Doppler mapping can be used as a method to identify topological structures with the assessment of qualitative and quantitative characteristics of the myocardium and valve apparatus.

We evaluated the correlation between pulmonary venous (PV) anatomy and acute and long-term success of PV isolation (PVI) with two balloon-based ablation catheter techniques. One hundred consecutive patients were analyzed in two equal groups treated with either the second-generation cryoballoon (CRYO) catheter or the visually guided laser ablation (VGLA) catheter. All patients underwent multi-detector computed tomography (CT) imaging. The primary and secondary efficacy endpoints were the procedural achievement of proven electrical isolation of all veins and freedom from atrial fibrillation (AF) within a 1-year follow-up period, respectively. Variant PV anatomy was observed in 32 % of patients in the CRYO group and in 40 % of patients in the VGLA group. All PVs were targeted with either the CRYO catheter (n = 199) or the VGLA catheter (n = 206). One hundred ninety-three of 199 PVs (97 %) were successfully isolated in the CRYO group and 194 of 206 PVs (94 %) in the VGLA group (p = 0.83). Over a 12-month follow-up, AF recurrence was documented in 11/45 (24 %) and 7/43 (16 %) patients in the CRYO and the VGLA groups, respectively (p = 0.21). In the CRYO group, a larger left inferior PV size was associated with worse long-term outcome (p = 0.001). In the VGLA group, a larger left superior PV size (p = 0.003) and more oval right inferior PV were associated with worse acute success (p = 0.038). There was no absolute cutoff between PV anatomy and clinical success. The variability of PV anatomy did not significantly compromise acute success of PVI or patient outcomes.

Aims The aim of the present study was to estimate the accuracy of a novel non-invasive epicardial and endocardial electrophysiology system (NEEES) for mapping ectopic ventricular depolarizations. Methods and results The study enrolled 20 patients with monomorphic premature ventricular contractions (PVCs) or ventricular tachycardia (VT). All patients underwent pre-procedural computed tomography or magnetic resonance imaging of the heart and torso. Radiographic data were semi-automatically processed by the NEEES to reconstruct a realistic 3D model of the heart and torso. In the electrophysiology laboratory, body-surface electrodes were connected to the NEEES followed by unipolar EKG recordings during episodes of PVC/VT. The body-surface EKG data were processed by the NEEES using its inverse-problem solution software in combination with anatomical data from the heart and torso. The earliest site of activation as denoted on the NEEES 3D heart model was compared with the PVC/VT origin using a 3D electroanatomical mapping system. The site of successful catheter ablation served as final confirmation. A total of 21 PVC/VT morphologies were analysed and ablated. The chamber of interest was correctly diagnosed non-invasively in 20 of 21 (95%) PVC/VT cases. In 18 of the 21 (86%) cases, the correct ventricular segment was diagnosed. Catheter ablation resulted in acute success in 19 of the 20 (95%) patients, whereas 1 patient underwent successful surgical ablation. During 6 months of follow-up, 19 of the 20 (95%) patients were free from recurrence off antiarrhythmic drugs. Conclusion The NEEES accurately identified the site of PVC/VT origin. Knowledge of the potential site of the PVC/VT origin may aid the physician in planning a successful ablation strategy.

Background Patients with atrial fibrillation (AF) routinely undergo different imaging modalities for the evaluation of the left atrial (LA) appendage to rule out thrombus prior to the AF ablation procedure. Recently, uninterrupted novel oral anticoagulants were introduced for patients undergoing atrial fibrillation (AF) ablation to minimize the peri-procedural thromboembolism risk. We performed a retrospective analysis to evaluate the safety of uninterrupted rivaroxaban and whether transesophageal (TEE) or intracardiac echocardiography (ICE) is necessary for patients undergoing AF ablation. Methods Data from 332 consecutive patients (42% females, aged 64 ± 11 years) with AF undergoing either TEE (n = 115) prior to catheter ablation or ICE (n = 217) for the detection of LA thrombus were analyzed. All patients were on uninterrupted rivaroxaban during, and for at least, 4 weeks before the procedure. Heparin bolus was administered in all patients before transseptal puncture to maintain a target activated clotting time of >350 s. Results A total of 277 patients (80.4%) had paroxysmal AF. The average CHA2DS2­VASc score was 2.11 ± 0.91 in the TEE group and 2.46 ± 0.61 in the ICE group. The CHA2DS2­VASc score was ≥2 in 64 (55.7%) and 214 (98.6%) patients in the TEE and ICE groups, respectively. The left atrial appendage was adequately visualized in all cases. None of the patients have an identifiable LA thrombus either in the TEE group or the ICE group. One (0.3%) thromboembolic periprocedural stroke occurred in a patient with long-standing persistent AF in the TEE group. Conclusions This study illustrates that performing AF ablation with ICE guidance on uninterrupted rivaroxaban for at least 4 weeks even without TEE is feasible and safe.

A 53-year-old woman with a history of sustained symptomatic ventricular tachycardia proceeded to catheter ablation. Endocardial electroanatomic mapping revealed ectopic focus in the posteroseptal right ventricular (RV) outflow tract. Focal radiofrequency ablations using outputs of 30 W of the

Recent studies have suggested that para-Hisian atrial tachycardia (AT) can be successfully ablated from the right atrium (RA), left atrium (LA), or noncoronary cusp (NCC) in the aorta; however, the best approach remains unclear.This study aimed to compare different approaches to radiofrequency catheter ablation (RFCA) of para-Hisian AT.We retrospectively analyzed 68 consecutive patients (49[72%] women; mean age 61 ± 13 years) treated with RFCA for this type of AT. Mapping of the RA (n = 68), LA (n = 21), and NCC (n = 52) was performed during AT to identify the earliest activation site and to apply RFCA.RFCA successfully terminated AT in the RA in 13 of 28 patients (46.4%), in the LA in 4 of 16 patients (25.0%), and in the NCC in 46 of 52 patients (88.5%) after 1 procedure (P.05). Atrioventricular block occurred only during RFCA in the RA in 4 of 28 patients (14.3%). After a mean follow-up of 33.5 ± 25.4 months, AT recurrence was observed in 5 of 13 patients (38.5%) ablated in the RA, 1 of 4 (25.0%) ablated in the LA, and 2 of 46 (4.4%) ablated in the NCC (P.05). RFCA in the LA was effective only if the local activation time (LAT) was earlier than that in the RA. RFCA in the NCC was successful regardless of the LAT (P.05).Mapping and ablation in the NCC should be always considered in cases of AT originating from the His bundle region, regardless of the LAT.

Background The underlying mechanisms of Brugada syndrome (BrS) are not completely understood. Recent studies provided evidence that the electrophysiological substrate, leading to electrocardiogram abnormalities and/or ventricular arrhythmias, is located in the right ventricular outflow tract ( RVOT ). The purpose of this study was to examine abnormalities of epicardial and endocardial local unipolar electrograms by simultaneous noninvasive mapping in patients with BrS. Methods and Results Local epicardial and endocardial unipolar electrograms were analyzed using a novel n oninvasive e pi‐ and e ndocardial e lectrophysiology s ystem ( NEEES ) in 12 patients with BrS and 6 with right bundle branch block for comparison. Fifteen normal subjects composed the control group. Observed depolarization abnormalities included fragmented electrograms in the anatomical area of RVOT endocardially and epicardially, significantly prolonged activation time in the RVOT endocardium (65±20 vs 38±13 ms in controls; P =0.008), prolongation of the activation‐recovery interval in the RVOT epicardium (281±34 vs 247±26 ms in controls; P =0.002). Repolarization abnormalities included a larger area of ST ‐segment elevation >2 mV and T‐wave inversions. Negative voltage gradient (−2.5 to −6.0 mV) between epicardium and endocardium of the RVOT was observed in 8 of 12 BrS patients, not present in patients with right bundle branch block or in controls. Conclusions Abnormalities of epicardial and endocardial electrograms associated with depolarization and repolarization properties were found using NEEES exclusively in the RVOT of BrS patients. These findings support both, depolarization and repolarization abnormalities, being operative at the same time in patients with BrS.

Understanding of the mechanisms of the atrial fibrillation (AF) termination may lead to improvement of AF treatment. The aim of this study was to investigate termination of AF in humans. We studied 6 patients (48.7±2.8 years old, 1 female) with paroxysmal AF undergoing a noninvasive ECG imaging (