Minimization of Energy Level Mismatch of PCBM and Surface Passivation for Highly Stable Sn-Based Perovskite Solar Cells by Doping n-Type Polymer.

Developing high-performance and stable Sn-based perovskite solar cells (PSCs) is difficult due to the inherent tendency of Sn2+ oxidation and, the huge energy mismatch between perovskite and Phenyl-C61-butyric acid methyl ester (PCBM), a frequently employed electron transport layer (ETL). This study demonstrates that perovskite surface defects can be passivated and PCBM's electrical properties improved by doping n-type polymer N2200 into PCBM. The doping of PCBM with N2200 results in enhanced band alignment and improved electrical properties of PCBM. The presence of electron-donating atoms such as S, and O in N2200, effectively coordinates with free Sn2+ to prevent further oxidation. The doping of PCBM with N2200 offers a reduced conduction band offset (from 0.38 to 0.21 eV) at the interface between the ETL and perovskite. As a result, the N2200 doped PCBM-based PSCs show an enhanced open circuit voltage of 0.79 V with impressive power conversion efficiency (PCE) of 12.98% (certified PCE 11.95%). Significantly, the N2200 doped PCBM-based PSCs exhibited exceptional stability and retained above 90% of their initial PCE when subjected to continuous illumination at maximum power point tracking for 1000 h under one sun.

Acute procedural efficacy and safety of a novel expandable diameter cryoballoon in atrial fibrillation ablation: Early results from a multicenter ablation registry.

INTRODUCTION: The major limitation of the current cryoballoon (CB) system is a fixed 28 mm balloon-size. We sought to analyze real-world early experience with novel-sized adjustable CB. METHODS: This multicenter observational study included 140 consecutive atrial fibrillation patients (71 years, 94 men, 86 paroxysmal) who underwent pulmonary vein (PV) isolation using expandable diameter CB capable of ablation at 28 or 31 mm. RESULTS: Out of 544 targeted PVs, 526 (96.7%) were successfully isolated by a size-adjustable CB with a 770 [690-870] second median application dose, while the remaining 18 required touch-up ablation. Among them, 326 (62.0%) PVs were isolated by a 31 mm balloon, and the rate was significantly higher for upper than lower PVs (73.0% vs. 45.7%, p < .0001) and highest for right superior (78.5%) and lowest for right inferior (39.9%) PVs. The biophysical parameters and time to isolation were comparable between the 28 and 31 mm balloons, however, the real-time PV potential monitoring capability was significantly higher for 31 mm than 28 mm balloons for the left superior PV. The esophageal temperature reached 15°C during left inferior PV ablation significantly more often with 31 mm than 28 mm balloons (43.1% vs. 18.2%, p = .008). Right phrenic nerve injury (PNI) occurred in 9 (6.4%) patients during applications (6 right superior, 2 right inferior PVs), and most occurred with a 31 mm balloon. CONCLUSIONS: Our real-world early data demonstrated high acute efficacy and safety of the novel-sized adjustable CB. The biophysical parameters were similar between the 28 and 31 mm balloons. No marked decrease in the incidence of PNI was observed even with 31 mm balloons.

Incidence of phrenic nerve injury during pulmonary vein isolation using different cryoballoons: data from a large prospective ablation registry.

AIMS: Phrenic nerve injury (PNI) is the most common complication during cryoballoon ablation. Currently, two cryoballoon systems are available, yet the difference is unclear. We sought to compare the acute procedural efficacy and safety of the two cryoballoons. METHODS: This prospective observational study consisted of 2,555 consecutive atrial fibrillation (AF) patients undergoing pulmonary vein isolation (PVI) using either conventional (Arctic Front Advance) (AFA-CB) or novel cryoballoons (POLARx) (POLARx-CB) at 19 centers between January 2022 and October 2023. RESULTS: Among 2,555 patients (68.8 ± 10.9 years, 1,740 men, paroxysmal AF[PAF] 1,670 patients), PVIs were performed by the AFA-CB and POLARx-CB in 1,358 and 1,197 patients, respectively. Touch-up ablation was required in 299(11.7%) patients. The touch-up rate was significantly lower for POLARx-CB than AFA-CB (9.5% vs. 13.6%, p = 0.002), especially for right inferior PVs (RIPVs). The touch-up rate was significantly lower for PAF than non-PAF (8.8% vs. 17.2%, P < 0.001) and was similar between the two cryoballoons in non-PAF patients. Right PNI occurred in 64(2.5%) patients and 22(0.9%) were symptomatic. It occurred during the right superior PV (RSPV) ablation in 39(1.5%) patients. The incidence was significantly higher for POLARx-CB than AFA-CB (3.8% vs. 1.3%, P < 0.001) as was the incidence of symptomatic PNI (1.7% vs. 0.1%, P < 0.001). The difference was significant during RSPV (2.5% vs. 0.7%, P < 0.001) but not RIPV ablation. The PNI recovered more quickly for the AFA-CB than POLARx-CB. CONCLUSIONS: Our study demonstrated a significantly higher incidence of right PNI and lower touch-up rate for the POLARx-CB than AFA-CB in the real-world clinical practice.

A novel catheter ablation strategy for non-paroxysmal atrial fibrillation combining cryoballoon, radiofrequency, and Marshall-vein ethanol ablations.

BACKGROUNDS: Catheter ablation for non-paroxysmal atrial fibrillation (non-PAF) remains challenging and more effective strategy has been required to reduce postoperative arrhythmia recurrences. This study aims to investigate the efficacy and safety of a novel extensive ablation strategy for non-PAF, that is based on a combination of cryoballoon (CBA), radiofrequency (RFA), and Marshall-vein ethanol ablations (EA-VOM). METHODS: The study was a single-center, retrospective observational study. We enrolled 171 consecutive patients who underwent de-novo catheter ablation for non-PAF under conscious sedation with a novel extensive ablation strategy that included CBA for pulmonary vein isolation (PVI) and left atrial roof ablation (LARA), RFA for mitral isthmus (MI) ablation, superior vena cava isolation, and other linear ablations and EA-VOM. Recurrence of atrial arrhythmias over 1 year, procedure outcomes, and procedure-related complications were investigated. RESULTS: A total of 139 (81.3%) patients remained in sinus rhythm during 1-year follow-up. Of the 139 patients, 51 patients (29.8%) received antiarrhythmic drugs. The mean procedure time was 204 ± 45 min. PVI and LARA ablation by CBA and MI block by RFA and EA-VOM were completed in 171 (100%) and 166 (97.1%) patients, respectively. No serious procedure-related complications were observed except for one case of delayed pericardial effusion. CONCLUSION: Approximately 80% of the study patients were AF-free during 1-year follow-up period after a single procedure based on the novel extensive ablation strategy combining CBA, RFA, and EA-VOM. This strategy for non-PAF may be preferred in terms of maintenance of sinus rhythm, safety even in high-risk patients, and relatively short procedure time.

Usefulness of the over-the-wire microelectrodes catheter in treatment of ventricular arrhythmia arising from the left ventricular summit.

BACKGROUND: This study was aimed to investigate the efficacy of the over-the-wire (OTW) microelectrodes catheter in coronary venous system (CVS) mapping and treatment of outflow tract ventricular arrhythmia (OTVA) arising from the vicinity of the left ventricular summit (LVS). METHODS: Consecutive 62 patients with idiopathic OTVA in whom the OTW microelectrodes catheter was routinely used for CVS mapping were analyzed. CVS mapping was performed for both main trunk (from great cardiac vein to anterior interventricular vein) and branches including the annular branch or septal branch. RESULTS: The earliest activation site (EAS) was within the CVS in 21 patients. Among them, the EAS was within the main trunk of the CVS in seven (33%) and within the branch of the CVS in 14 (67%) patients. Radiofrequency catheter ablation was started at an anatomically adjacent site to the EAS, which eliminated OTVA in 16 (76%) patients　(the endocardial LVOT in 10 and the aortic sinus of Valsalva in six patients). For the remaining five patients with unsuccessful catheter ablation at an anatomically adjacent site, targeted OTVA was eliminated by catheter ablation at the EAS within the CVS in two patients and by chemical ablation with ethanol injection in one patient, resulting in the overall success rate of 90% (19/21). CONCLUSION: The OTW microelectrodes-guided ablation of OTVA from the vicinity of the LVS was effective. In maximizing the efficacy of ablation, CVS branch mapping is important since the earliest activation was commonly recorded not in the main trunk but within the branch of the CVS.

L1 acquisition of the tense-aspect markers -ess (past-perfective) and -ko iss (imperfective) in Korean.

This study investigated whether Korean children follow the acquisition pattern predicted by the Aspect Hypothesis (Shirai & Andersen, 1995), and the relationship between caretakers' and children's speech. Accordingly, we analyzed a Korean corpus (Ryu-Corpus) on the CHILDES database (MacWhinney, 2000), which comprised longitudinal video-recorded interactions of three Korean children and their caregivers. Results indicate that the children used the past marker -ess principally with telic verbs, consistent with the Aspect Hypothesis. Each child's usage closely reflects the caretaker's frequency, yielding a high correlation (τb = 0.79). However, the acquisition of the imperfective marker -ko iss did not show a predicted association with activity verbs, contrary to the Aspect Hypothesis. Furthermore, caretakers' input did not correlate with the children's utterances of the imperfective marker (τb = 0.40). We argue that multiple factors such as input frequency, language-specific organization of aspectual semantics, and individual differences should be considered to explain tense-aspect acquisition.

Coalescence-Driven Verticality in Mesoporous TiO2 Thin Films with Long-Range Ordering.

Mesoporous semiconducting films with continuous interconnectivity and minimal tortuosity, such as densely ordered arrays of vertical channels, are ideal for ensuring a maximal surface area at the heterojunction to increase the density of charges or photons. While the design of these films with nanostructures below 50 nm using modern lithography is not feasible, continuously perpendicular pores can be obtained throughout a TiO2 film using a traditional soft-templating approach and lyotropic crystal engineering. We demonstrate here that a polystyrene-b-poly(ethylene oxide) block copolymer in a three-solvent system can self-assemble into a body-centered cubic Im3̅m template. The long-range three-dimensional periodicity of the template combined with a high degree of vertical contraction results in coalescence of the pores into orthogonal channels that are strongly interconnected with their nearest neighbors in the (011̅) plane. This work presents evidence of lateral long-range ordering with continuously transverse vertical porosity in a TiO2 material, which will enable functional applications, such as filtration, sensing, catalysis, and optoelectronics. To this end, we demonstrate the ability of the films to template and host methylammonium lead iodide perovskite nanocrystals.

Pulmonary vein narrowing after visually guided laser balloon ablation: Occurrence and clinical correlates.

INTRODUCTION: There are limited data focusing on pulmonary vein (PV) narrowing following ablation using a visually guided laser balloon (VGLB). We sought to assess the frequency and predictors of PV narrowing after VGLB ablation. METHODS AND RESULTS: Patients with paroxysmal atrial fibrillation treated with VGLB were screened. Study participants underwent contrast-enhanced computed tomography (CT) scanning before and 6 months after the procedure. We defined 25% to 49%, 50% to 74%, and 75% to 100% reduction in PV cross-sectional area as mild, moderate, and severe narrowing, respectively. Of 146 PVs in 38 patients analyzed, severe narrowing developed in two right superior and one right inferior PV. Moderate or severe narrowing occurred in 40 veins (27% of all PVs, 50% of the right superior, 22% of the right inferior, 21% of the left superior, and 14% of the left inferior PV). In PVs with moderate-severe narrowing, the baseline orifice area was significantly larger (4.1 [interquartile range, 3.2-4.8] vs 2.5 [1.9-3.3] cm2 , P < .0001), the narrowest region of stenosis was significantly more distal into the vessel (1.9 [0.7-2.9] vs 0 [0-1.7] mm from the orifice, P = .0006) and the total amount of energy delivered per vein was significantly greater (5190 ± 970 vs 4626 ± 1573 J, P = .018) than in PVs with mild or no significant narrowing. The baseline orifice area independently predicted moderate-severe narrowing in multivariate analysis (odds ratio, 1.8 [1.3-2.5] per 1 cm2 increase, P = .0003). No patient exhibited any signs or symptoms of PV stenosis. CONCLUSIONS: Baseline PV orifice area, ablating distally inside the veins, and total amount of laser energy are associated with PV narrowing after VGLB ablation.

Clinical outcome of pulmonary vein isolation alone ablation strategy using VISITAG SURPOINT in nonparoxysmal atrial fibrillation.

BACKGROUND: Recent studies have shown the improvement in long-term effectiveness with standardized pulmonary vein isolation (PVI) aimed at creating durable and contiguous lesions with VISITAG SURPOINT (VS) in paroxysmal atrial fibrillation (PAF). OBJECTIVE: We aimed to assess efficacy of PVI alone strategy using VS in non-PAF patients and evaluate factors associated with corresponding clinical outcomes. METHODS: Consecutive patients who underwent PVI for persistent/long-standing persistent AF between May 2017 to July 2019 were studied retrospectively. PVI was performed with 30-50 W guided by VS (posterior target: 400-500, anterior target: 500). Left atrial voltage maps were created during atrial pacing after PVI. RESULTS: A total of 140 patients (119 males, age 62 ± 10 years, long-standing persistent AF: 35) were included and followed for median of 454 days. No adverse events were reported in any patients during periprocedural and follow-up period of up to 28 months. Kaplan-Meier analysis estimated that freedom from atrial tachycardia or AF (AT/AF) without antiarrhythmics at 1-year was 70%. Radiofrequency delivery with higher power was associated with increased first-pass isolation rate, but not with freedom from AT/AF. In multivariate analysis, long-standing persistent AF and % low-voltage zone (%LVZ) were independent predictors of clinical outcome. The best cut-off value of %LVZ for predicting AT/AF recurrence was 3.24%. Freedom from AT/AF was 88% in patients with persistent AF and %LVZ < 3.24%, while 27% in those with long-standing persistent AF and %LVZ ≥ 3.24%. CONCLUSIONS: PVI alone using VS was associated with excellent 1-year success in patients with persistent AF and %LVZ < 3.24%, but was insufficient in those with long-standing persistent AF and/or %LVZ ≥ 3.24%.

Photoinduced ion-redistribution in CH3NH3PbI3 perovskite solar cells.

We use photoinduced absorption spectroscopy (PAS) to study the ionic motion in CH3NH3PbI3 perovskite solar cells, consisting of indium tin oxide (ITO)/NiOx/perovskite/phenyl-C61-butyric-acid-methyl ester (PCBM)/aluminum-doped zinc oxide (AZO)/ITO. We observed a slow (∼50 mHz) spectral blue shift (∼10-4 eV) under modulated 520 nm illumination, which we interpreted in terms of the modulation in the bulk ion density. Numerical simulation shows that the mobile ion moves in and out from the double layers at the perovskite/charge transport layer interfaces in order to recover the bulk charge neutrality tipped off-balance by the photocarriers. The diffusion coefficient of the ion is 10-10 to 10-11 cm2 s-1, when we assume that the characteristic time constant of the ion motion is governed by the diffusion.

Ventricular tachycardia in nonischemic cardiomyopathy: Anteroseptal vs inferolateral origin based on ICD ventricular electrogram timing.

INTRODUCTION: The majority of patients with nonischemic cardiomyopathy (NICM) present a perivalvular substrate that is either predominantly antero-septal (AS) or infero-lateral (IL), corresponding to specific ventricular tachycardia (VT) morphologies. The relative timing of far-field and near-field ventricular electrograms (EGMs) from stored implantable cardioverter-defibrillator (ICD) events of VT may be used to distinguish AS from IL VT in NICM. METHODS AND RESULTS: We analyzed 48 patients with NICM with either a primarily AS (54%) or IL (56%) VT source undergoing catheter ablation between 2003 and 2018. Only patients with retrievable ICD-EGMs of spontaneous VT events which could be matched with VTs induced during the ablation procedure were included. A total of 56 VT events (52% AS origin and 48% IL origin) were analyzed, yielding a mean far-field to near-field interval of 31 ± 13 milliseconds for AS VTs and 47 ± 19 milliseconds for IL VTs (P = .001). At receiver operating characteristic analysis (AUC = 0.734), a far-field to near-field interval of ≥ 60 milliseconds ruled out AS VTs in 29 (100%) cases and diagnosed IL VTs with a positive predictive value (PPV) of 100% and a negative predictive value (NPV) of 63%. An interval of ≤ 20 milliseconds ruled out IL VTs in 25 (93%) cases and diagnosed AS VTs with a PPV of 83% and NPV of 57%. Significant overlap between the two groups was observed among far-field to near-field intervals in between 20 milliseconds and 60 milliseconds. CONCLUSIONS: The relative timing of far-field and near-field EGMs from stored clinical ICD events of VT can be helpful to differentiate AS vs IL origin of VT in NICM.

Usefulness of ICD electrograms analysis to distinguish endocardial vs epicardial ventricular tachycardia in arrhythmogenic right ventricular cardiomyopathy.

INTRODUCTION: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by an epicardial (EPI) to endocardial (ENDO) fibrofatty infiltration of the RV predisposing to both EPI and ENDO ventricular tachycardia (VT). The relative timing between the VT QRS onset on the far-field ventricular electrogram (VEGM) to the local activation time recorded at the RV apex on the near-field VEGM from stored implantable cardioverter-defibrillator (ICD) events of VT can be helpful to discriminate ENDO from EPI VT in ARVC. METHODS AND RESULTS: We analyzed consecutive ARVC patients undergoing catheter ablation between 2006 and 2018. Only patients with retrievable ICD VEGMs of clinical VTs which could be matched with VTs induced at the time of ablation were included. A total of 26 VT events (16 ENDO, 10 EPI) from 19 ARVC patients were examined, yielding a mean far-field to near-field interval of 33 ± 15 ms for ENDO VTs and 52 ± 20 ms for EPI VTs (P = .020). At receiver-operating characteristic analysis, a far-field to a near-field interval of 60 ms or more ruled out ENDO VTs in 16 (100%) cases and identified EPI VTs with a positive predictive value (PPV) of 100% and a negative predictive value (NPV) of 73%. An interval of less than or equal to 30 ms ruled out EPI VTs in eight (80%) cases and diagnosed ENDO VTs with a PPV of 80% and an NPV of 50%. CONCLUSION: Far-field to near-field ICD VEGM timing may be used to predict ENDO vs EPI VT in ARVC before ablation, indicating an ENDO origin if the timing is less than or equal to 30 ms and an EPI origin if greater than or equal to 60 ms.

Catheter ablation of premature ventricular complexes with low intraprocedural burden guided exclusively by pace-mapping.

BACKGROUND: Catheter ablation (CA) of idiopathic premature ventricular complexes (PVCs) is typically guided by both activation and pace-mapping, with ablation ideally delivered at the site of the earliest local activation. However, activation mapping requires sufficient intraprocedural quantity of PVCs. This study aimed to investigate the outcome of CA of infrequent PVCs guided exclusively by pace-mapping. METHODS: We retrospectively analyzed all patients undergoing CA of idiopathic PVCs between 2014 and 2017. RESULTS: Among 327 patients, 24 (7.3%) had low intraprocedural PVC burden despite isoproterenol, including two patients with zero PVCs, rendering activation mapping impractical/impossible. All 24 had a history of symptomatic PVCs. During ablation, a median of 27 (17-55) pace-maps were performed, with best median PASO score of 97 (96-98)%. A median of 12 (8.75-18.75) radiofrequency (RF) lesions were delivered with 11.4 (8.5-17.6) minutes of total RF time. Clinical success, defined as more than 80% reduction in the burden of previously frequent PVCs and/or absence of symptoms as well as any documented clinical PVCs among those with infrequent or exercise-induced PVCs, was achieved in 19 (79%) patients over 9.2 (2.0-15.0) months of follow-up. CONCLUSIONS: When activation mapping cannot be performed due to inadequate intraprocedural PVC burden, detailed pace-mapping can frequently identify the precise arrhythmia site of origin, thereby guiding successful CA.

Papillary muscle ventricular arrhythmias in patients with arrhythmic mitral valve prolapse: Electrophysiologic substrate and catheter ablation outcomes.

BACKGROUND: Mitral valve prolapse (MVP) is a common valve condition and has been associated with sudden cardiac death. Premature ventricular contractions (PVCs) from the papillary muscles (PMs) may play a role as triggers for ventricular fibrillation (VF) in these patients. OBJECTIVES: To characterize the electrophysiological substrate and outcomes of catheter ablation in patients with MVP and PM PVCs. METHODS: Of 597 patients undergoing ablation of ventricular arrhythmias during the period 2012-2015, we identified 25 patients with MVP and PVCs mapped to the PMs (64% female). PVC-triggered VF was the presentation in 4 patients and a fifth patient died suddenly during follow-up. The left ventricle ejection fraction (LVEF) was 50.5% ± 11.8% and PVC burden was 24.4% ± 13.1%. A cardiac magnetic resonance imaging was performed in nine cases and areas of late gadolinium enhancement were found in four of them. A detailed LV voltage map was performed in 11 patients, three of which exhibited bipolar voltage abnormalities. Complete PVC elimination was achieved in 19 (76%) patients and a significant reduction in PVC burden was observed in two (8%). In patients in which the ablation was successful, the PVC burden decreased from 20.4% ± 10.8% to 6.3% ± 9.5% (P = 0.001). In 5/6 patients with depressed LVEF and successful ablation, the LV function improved postablation. No significant differences were identified between patients with and without VF. CONCLUSIONS: PM PVCs are a source of VF in patients with MVP and can induce PVC-mediated cardiomyopathy that reverses after PVC suppression. Catheter ablation is highly successful with more than 80% PVC elimination or burden reduction.

Anatomical proximity dictates successful ablation from adjacent sites for outflow tract ventricular arrhythmias linked to the coronary venous system.

AIMS: Catheter ablation of outflow tract ventricular arrhythmias (OTVAs) with the earliest activation within the coronary venous system (CVS) can be challenging. When ablation from the CVS is not feasible or ineffective, an approach from anatomically adjacent site(s) can be considered. We report the outcomes of an anatomical approach for OTVAs linked to the CVS. METHODS AND RESULTS: We retrospectively analysed 665 OTVA patients. Of these, 65 (9.8%) had the earliest activation within the CVS. In 53 (82%) cases, an anatomical approach was attempted. The targeted adjacent anatomical structure was the endocardial left ventricular outflow tract (LVOT) in 24 (45%), the left coronary cusp or the left/right cusp junction in 17 (32%) patients, and the right ventricular outflow tract (RVOT) in 12 (23%). The anatomical approach was successful in 26 (49%) patients (27% from the coronary cusps, 65% from the LVOT, and 8% from the RVOT). The difference in activation times between the earliest activation site within the CVS and the targeted site was not significantly different between the successful and unsuccessful groups (14.2 ± 11.2 ms vs. 13.2 ± 9.3 ms; P = 0.89). The anatomical distance from the earliest activation site to the targeted site was shorter for the successful group (9.7 ± 2.4 mm vs. 13.1 ± 6.5 mm; P < 0.05). In particular, when the anatomical distance was >12.8 mm, anatomical approach was successful in only 1/13 (8%). CONCLUSION: In patients with OTVAs linked to the CVS, an anatomical approach targeting an adjacent site can be effective, particularly when the distance between the sites is <12.8 mm.

Long-term outcome and mode of recurrence following noninducibility during noninvasive programmed stimulation after ventricular tachycardia ablation.

BACKGROUND: Noninducibility of ventricular tachycardia (VT) at noninvasive programmed stimulation performed shortly following ablation (negative NIPS) predicts low risk of the medium-term recurrence. This study aimed to evaluate long-term rate and mode of recurrence following negative NIPS. METHODS: We extended follow-up on patients in whom no VT could be induced at NIPS following ablation between 2008 and 2010. Recurrent VTs were categorized as "Original clinical" if they matched VT that had occurred spontaneously prior to the index ablation; "Original nonclinical" if they matched VT that was induced during the index ablation but had not occurred spontaneously; or "New." Among those undergoing repeat ablation, the area ablated to treat the recurrent VT was categorized as "Targeted initial scar" if it was targeted during the index procedure; "Untargeted initial scar" if it was present but not targeted during the index procedure; or "New scar" if it was not present during the index procedure. RESULTS: Of 60 patients with negative NIPS, 18 (30%) had recurrent VT and nine underwent repeat ablation over (4.1 ± 3.2) years follow-up. Of 23 recurrent VTs, 18 (78%) were "New." During repeat ablations, six (46%) of the 13 recurrent VTs were ablated in "untargeted initial scar" and four (31%) in "new scar." CONCLUSIONS: When spontaneous or inducible VTs are eliminated with ablation and no longer inducible during NIPS, these VTs are unlikely to recur during long-term follow-up. More commonly, new VTs occur, which are either associated with areas of scar not present or not targeted during the initial ablation.

Magnetocardiography Using a Magnetoresistive Sensor Array.

In previous magnetocardiography studies, magnetocardiograms (MCGs) have been obtained using superconducting quantum interference device (SQUID) systems. SQUID is the most sensitive instrument for measuring low-frequency magnetic fields, but it requires liquid helium for cooling, so operating costs are high. In contrast, magnetoresistive (MR) magnetometers function by detecting the change in resistance, caused by an external magnetic field, and have much lower costs. This study was aimed to evaluate feasibility of the MR sensor array for acquiring MCGs.We used an MR sensor array, which was developed for measuring magnetic fields in the picotesla range, with a reduced noise level (TDK Corporation, Tokyo, Japan). A 30-channel MR sensor array was placed in a magnetically shielded room, and the cardiac magnetic field over the anterior chest walls of five healthy subjects was recorded.For all five subjects, MCGs were successfully recorded using the MR sensor array. The cardiac magnetic field corresponding to P, QRS, and T waves on an electrocardiogram (ECG) was detectable by signals averaging 272 ± 27.5 beats.An MR sensor array can be used to measure cardiac magnetic fields. Our results will contribute to the development of low-cost devices for recording MCGs, which will help develop non-invasive diagnostics in cardiovascular medicine.

QRS morphology shift following catheter ablation of idiopathic outflow tract ventricular arrhythmias: Prevalence, mapping features, and ablation outcomes.

INTRODUCTION: In patients with monomorphic idiopathic outflow tract ventricular arrhythmias (OT-VAs), catheter ablation (CA) at the earliest activation site can result in a shift in QRS morphology indicating a change in the activation patterns. This study aimed to investigate the prevalence, mapping features, and ablation outcomes of OT-VAs displaying a QRS morphology shift following CA. METHODS AND RESULTS: We retrospectively analyzed 446 patients with monomorphic OT-VAs. A QRS morphology shift following CA was observed in 17 (4%) patients. Initially, the earliest activation site was within the right ventricular outflow tract (RVOT) in one (6%) patient, the left ventricular outflow tract (LVOT) in 10 (59%) patients (left coronary cusp/right coronary cusp junction in seven patients and LVOT endocardium in three patients), and within the distal coronary venous system in six (35%) patients. The VA was suppressed in all 17 patients, but VA recurrence with a different QRS morphology was observed after a waiting period. The recurrent VA was remapped in all patients and was eliminated targeting the new earliest site in 15 (88%) cases. In 11 of 15 successful cases, the ablation site for the recurrent VA shifted to an anatomical structure distinct from but adjacent to the initial site. In the remaining four patients, the recurrent VA was eliminated within the same anatomical structure. CONCLUSIONS: In patients with idiopathic OT-VAs, a QRS morphology shift following CA can be observed in 4% of the cases. In these cases, detailed remapping is necessary since the successful ablation site for the VAs with altered QRS morphology shifts to different anatomical structures in most patients.

Epicardial ventricular tachycardia in ischemic cardiomyopathy: Prevalence, electrophysiological characteristics, and long-term ablation outcomes.

INTRODUCTION: The characteristics of the epicardial (EPI) substrate responsible for ventricular tachycardia (VT) in ischemic cardiomyopathy (ICM) are undefined, and data on the long-term outcomes of EPI catheter ablation limited. We evaluated the prevalence, electrophysiologic features, and outcomes of catheter ablation of EPI VT in ICM. METHODS AND RESULTS: From December 2010 to June 2013, a total of 13 of 93 (14%) patients with ICM underwent catheter ablation at our institution and had conclusive evidence of critical EPI substrate demonstrated to participate in VT with activation, entrainment and/or pace mapping during sinus rhythm (two other patients underwent EPI mapping but had no optimal ablation targets). The electrophysiologic substrate characteristics and activation/entrainment mapping data were compared with a reference group of ICM patients without evidence of critical EPI substrate (N = 44), defined as a complete procedural success (noninducibility of any VT at programmed stimulation) after endocardial (ENDO)-only ablation. Patients with failed EPI access (N = 2) or history of cardiac surgery (N = 92) were excluded from the study. All 13 patients had evidence of abnormal EPI substrate with fractionated/late/split electrograms and low-bipolar voltage areas. The critical VT ablation sites were all located within the EPI bipolar "dense" scar (<1.0 mV) opposite the ENDO bipolar scar in 77% of cases and extending beyond the ENDO bipolar scar (within the ENDO unipolar low-voltage area) in the remaining patients. Compared with the reference ENDO-only group, patients with EPI VT had a smaller ENDO bipolar scar area, 54.0 (37.1-84) vs 86.7 (55.6-112) cm2 ; P = 0.0159, with a similar extent of ENDO unipolar low voltage. No other substrate characteristics or location differed between the two groups. After 35.2 ± 24.2 months of follow-up, VT-free survival was 73% in patients with EPI VT compared with 66% in the ENDO-only group (log-rank P = 0.56). CONCLUSIONS: The presence of the critical EPI substrate responsible for VT can be demonstrated in at least 14% of patients with ICM. The majority of EPI critical ablation sites are distributed opposite the ENDO bipolar scar area and catheter ablation is effective in achieving long-term arrhythmia control.

Safety and Efficacy of Transvenous Lead Extraction With a High-Frequency Excimer Laser　- A Single Center Experience.

BACKGROUND: Transvenous lead extractions have been performed using 40-Hz laser sheaths. Recently, a new 80-Hz laser sheath became available, but only a few reports have compared the effectiveness of the 40- and 80-Hz laser sheaths. Methods and Results: This study included 215 patients. Lead extractions using only laser sheaths were analyzed. The clinical characteristics, extraction parameters, and extraction tools were evaluated. The procedures were performed with 40-Hz sheaths in 150 patients (group 1: 270 leads) and 80-Hz sheaths in 65 (group 2: 99 leads). No statistically significant differences were observed in the clinical parameters except for sex. The mean implant duration was 95.3±86.0 and 78.2±56.8 months in groups 1 and 2, respectively (P=0.07). The respective mean laser time and number of laser pulses were 48.5±52.1 and 48.1±56.1 s (P=0.96) and 2,035.0±2,384.0 and 3,955.1±2,339.3 pulses (P<0.0001). Complete removal was achieved for 97.4% of the leads and in 98.0% in both groups (P=0.38). Major complications occurred in 2.0% and 3.1% of the patients in groups 1 and 2, respectively (P=0.94). CONCLUSIONS: Transvenous lead extraction using high-frequency laser sheaths was as highly successful as with low-frequency laser sheaths in Japanese patients.