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Background Uninterrupted dabigatran during atrial fibrillation (AF) ablation is now established as the standard therapy. However, there are few reports on the effects of uninterrupted dabigatran on the intensity of anticoagulation during AF ablation. Methods We retrospectively analyzed 247 consecutive patients who underwent AF ablation in our hospital from January 2017 to December 2018. Patients who took warfarin or uninterrupted direct oral anticoagulants (DOACs) except for dabigatran were excluded. 89 patients underwent ablation with uninterrupted dabigatran (uninterrupted group, male 71, mean age 59.6 ± 14.0) and 124 with interrupted DOACs (interrupted group, male 105, mean age 56.9 ± 12.9) during AF ablation. The initial ACT level, proportion of ACT levels of more than 300 s, and total amount of heparin were compared. Furthermore, the incidence of procedure complications was also evaluated. Results The initial ACT levels were significantly higher in the uninterrupted group, and the total number of ACTs of more than 300 s was significantly higher in the uninterrupted group (uninterrupted vs. interrupted; initial ACT level, 315.6 ± 59.8 vs. 264.5 ± 48.6, p

Local impedance (LI) parameters of IntellaNav STABLEPOINT for successful pulmonary vein isolation (PVI) of atrial fibrillation (AF) remain unclear. The purpose of this study was to seek LI data achieving successful PVI.Consecutive AF patients who underwent catheter ablation with STABLEPOINT were prospectively enrolled in two centers. PVI was performed under a constant 35-or 40-watt power, 20-s duration, and5-g contact force. The operators were blinded to the LI data. The characteristics of all ablation points with/without conduction gaps (Unsuccess or Success tags) after the first-attempt PVI were evaluated for the right/left PVs and anterior/posterior wall (RPV/LPV and AW/PW, respectively), and cutoff values of LI data were calculated for successful lesion formation.A total of 5257 ablation points in 102 patients (65 [58-72] years old, 65.7% male) were evaluated. The LI drop values were higher in the Success tags than Unsuccess tags on the LPV-AW and RPV-AW/PW (p .001), except for the LPV-PW (p = .105). The %LI drop values (LI drop/initial LI) were higher for the Success tags in all areas (15.8 [12.2%-19.6%] vs. 11.6 [9.7%-15.6%] in LPV-AW: p .001, 15.0 [11.5%-19.3%] vs. 11.4 [8.7%-17.3%] in LPV-PW: p = .035, 15.3 [11.5%-19.4%] vs. 9.9 [8.1%-13.7%] in RPV-AW: p .001, and 13.3 [10.1%-17.4%] vs. 8.1 [6.3%-9.5%] in RPV-PW, p .001). The LI drop and %LI drop cutoff values were 20.0 ohms and 11.6%, respectively.An insufficient LI drop with STABLEPOINT was associated with a gap formation during PVI, and the best cutoff values for the LI drop and %LI drop were 20.0 ohms and 11.6%, respectively.

A novel irrigation catheter (QDOT MICRO™) has been introduced, which enables a surface temperature-controlled ablation combined with tip cooling. However, the detailed description of its complex behavior and effect on the incidence of pops and lesion formation remains elusive. This study aimed to systematically investigate the ablation characteristics, feedback behavior, and incidence of steam pops in a simplified ex vivo swine model.Using swine ventricular tissue perfused with saline at 37°C, we systematically created lesions with 4×3 combinations of the wattage (20, 30, 40, and 50 W) and contact force (CF, 10, 30, and 50 g). Ablation was continued for either 120 s or until a steam pop occurred and repeated 10 times with each setting. The lesion geometry, ablation index, feedback dynamics, and conditions underlying the steam pops were measured and analyzed.Steam pops occurred particularly frequently in combinations of a low CF and high power (10 g vs. 30 g+50 g [p .0001]; 40 W+50 W vs. 20 W+30 W [p .0001]). Failure to activate a feedback process was associated with a 5.1 times higher incidence of steam pops (21/109 vs.11/11, [95% CI 3.499-7.716], p .0001). The wattage feedback was particularly evident with a high CF (30 and 50 g) and high initial wattage (40 and 50 W). The average delivered wattage at 27 W predicted the occurrence of steam pops.The temperature-controlled ablation with the QDOT MICRO™ demonstrated a complex feedback behavior, which contributed to a reduced incidence of steam pops and prolonged lead time to the pops.

Background The local impedance (LI) reflects the electrical catheter-tissue coupling and correlates with the local tissue temperature. However, there have been few clinical studies showing the recommended method for LI monitoring catheters. This study aimed to investigate the optimal ablation setting for this catheter in an in vitro experimental model. Methods LI monitoring catheters were used in an excised swine heart experimental model. The tissue contact force (CF) was directly monitored from an external weight scale. Radiofrequency ablation was performed with a combination of various energy power settings (30, 40, and 50W), and various CFs (10, 30, and 50g) for 60 seconds. The correlation between the LI-related indexes, power, and CF with the lesion formation was statistically analyzed. Results A positive correlation between the LI or lesion formation and CF was observed under all powers. Although the LI drop always correlated with the maximum lesion depth, lesion diameter, and lesion volume, the coefficient of the correlation value was lower under a high CF (lesion depth, diameter, and volume; 10g, r=0.8064, r=0.8389, r=0.8477; 30g, r=0.7590, r=0.8063, r=0.8060; 50g r=0.5555, r=0.5701, and r=0.5678, respectively). Steam pops occurred only under a 50W ablation and the LI drop cutoff value for steam pops was 46Ω. Conclusion The same LI drop did not always lead to the same lesion size when the CF differed. Monitoring the LI and not exceeding 46Ω would be useful for a safe ablation. This article is protected by copyright. All rights reserved.

In adult patients, subcutaneous implantable cardioverter defibrillators (S-ICDs) have been reported to be non-inferior to transvenous ICDs with respect to the incidence of device-related complications and inappropriate shocks. Only a few reports have investigated the efficacy of S-ICDs in the pediatric field. This study aimed to investigate the utility and safety of S-ICDs in patients ≤18 years old.This study was a multicenter, observational, retrospective study on S-ICD implantations. Patients18 years old who underwent S-ICD implantations were enrolled. The detailed data on the device implantations and eligibility tests, incidence of appropriate- and inappropriate shocks, and follow-up data were assessed.A total of 62 patients were enrolled from 30 centers. The patients ranged in age from 3 to 18 (median 14 years old [IQR 11.0-16.0 years]). During a median follow up of 27 months (13.3-35.8), a total of 16 patients (26.2%) received appropriate shocks and 13 (21.3%) received inappropriate shocks. The common causes of the inappropriate shocks were sinus tachycardia (n = 4, 30.8%) and T-wave oversensing (n = 4, 30.8%). In spite of the physical growth, the number of suitable sensing vectors did not change during the follow up. No one had any lead fractures or device infections in the chronic phase.Our study suggested that S-ICDs can prevent sudden cardiac death in the pediatric population with a low incidence of lead complications or device infections. The number of suitable sensing vectors did not change during the patients' growth.

Whether diagnostic computed tomography (CT) scans to cardiac implantable electronic devices (CIED) is safe in recent models remains unknown.A two-centers observational study. Over 14 years, consecutive 2362 chest CT scans (1666 pacemakers [PMs], 145 cardiac resynchronization therapy PM, 316 implantable cardioverter-defibrillator, and 233 cardiac resynchronization therapy defibrillator) were interrogated and monitored upon imaging.Electromagnetic interference occurred only in a few old models: InSync 8040 (n = 14), InSync III Marquis (n = 1), and Kappa (n = 4), which resulted no adverse events.CIEDs, especially recent ones, are confirmed safe on chest CT.

Sub-optimal atrioventricular delay (AVD) is one of the main causes of non-responder for cardiac resynchronization therapy (CRT). Recently, device-based algorithms (DBAs) that provide optimal AVD based on intracardiac electrograms, have been developed. However, their long-term effectiveness is still unknown. This study aims to investigate the effect of optimizing AVD using DBAs over a long period, on the prognosis of patients undergoing CRT. A total of 118 patients who underwent CRT at our hospital between April 2008 and March 2018, were retrospectively reviewed; 61 of them with optimizing AVD using DBAs were classified into the treated group (group 1), and the remaining 57 were classified into the control group (group 2). The median follow-up period was 46.0 months. The responder and survival rate in group 1 were significantly better than those in group 2 (group 1 vs. group 2: responder rate = 64% vs. 46%, p = 0.046; survival rate: 85.2% vs. 64.9%, p = 0.02). Moreover, investigating only the non-responder population showed that group 1 had an improved survival rate compared to group 2 (group 1 vs. group 2 = 72.7% vs. 45.1%, p = 0.02). Optimizing AVD using DBAs was a significant contributor to the improved survival rate in CRT non-responders in multivariate analysis (HR 3.6, p = 0.01). In conclusion, the long-term optimizing AVD using DBAs improved the survival rate in CRT and the prognosis of CRT non-responders, as well.

Background Local impedance (LI) has emerged as a new technology that informs on electrical catheter-tissue coupling during radiofrequency (RF) ablation. Recently, IntellaNav StablePoint, a novel LI-enabled catheter that equips contact force (CF) sensing, has been introduced. Although StablePoint and its predecessor IntellaNav MiFi OI share the common technology that reports LI, distinct mechanics for LI sensing between the 2 products raise a concern that the LI-RF lesion formation relationship may differ. Methods In an ex vivo swine cardiac tissue model, we investigated the initial level and range of a reduction in LI during a 60-second RF ablation and the resultant lesion characteristics at 9 combinations of 3 energy power (30, 40, and 50W) and CF (10, 30, and 50g) steps. Correlations and interactions between CF, LI, wattage, and formed lesions were analyzed. Incidence of achieving LI drop plateau and that of a steam pop were also determined. Results Positive correlations existed between CF and initial LI, CF and absolute/relative LI drop, CF and lesion volume, and LI drop and lesion volume. At the same LI drop, wattage-dependent gain in lesion volume was observed. Steam pops occurred in all CF steps and the prevalence was highest at 50W. LI drop predicted a steam pop with a cutoff value at 89Ω. Conclusion In StablePoint, wattage crucially affects LI drop and lesion volume. Because 30W ablation may by underpowered for intramural lesion formation and 50W often resulted in a steam pop, 40W appears to achieve the balance between the safety and efficacy. This article is protected by copyright. All rights reserved.

The ablation index (AI), developed as a radiofrequency (RF) catheter ablation composite component endpoint, which incorporates contact force (CF), time, and power in a weighted formula, has been reported to be useful for a durable pulmonary vein isolation (PVI) to treat atrial fibrillation (AF). No study has reported the target AI value for the SVC isolation (SVCI). In this study, we aimed to investigate the target AI for the SVCI.Thirty-six AF patients who underwent an initial SVCI were enrolled. Ablation was performed at 556 points. The sites where dormant conduction was induced or additional ablation was needed were defined as touch up sites (n = 36). We compared the energy deliver time, power, generator impedance (GI) drop, local bipolar voltage, contact force (CF), force-time integral (FTI), and AI between the touch up sites and the no touch up sites (n = 520).The FTI and AI were significantly lower at the touch up sites (touch up sites vs. no touch up sites; FTI, 126.5 [99.3-208.8] vs. 244 [184-340.8], p 0.0001; AI, 350.1 ± 43.6 vs. 277.2 ± 21.8, p 0.0001). The median value of the AI at the no touch up sites was 350, and no reconnections were seen where the minimum AI value was more than 308. Most of the touch up sites were located in the anterior wall and lateral wall (anterior wall, 20/36 sites [55.6%]; lateral wall, 10/36 sites [27.8%]; septal wall, 6/36 sites [16.7%]; posterior wall, 0/36sites [0.0%]).The target AI value for the SVCI should be 350, and at least 308 would be needed.

Introduction Detailed three-dimensional (3D) mapping has been useful for effective radiofrequency catheter ablation. The Rhythmia system can create atrio-ventricular dual-chamber mapping, which reveals the atrial and ventricular potentials all at once in the same map. The aim of this study was to investigate the utility of mapping the atrium and ventricle simultaneously with a high-density 3D mapping system for the ablation of accessory pathways (AP). Methods From July 2015 to August 2020, 111 patients underwent ablation of APs. Dual-chamber maps were created in 50 patients (median age 15 [10-54], 32 male [64.0%]), while 61 patients underwent radiofrequency (RF) ablation with conventional single-chamber 3D maps. The background characteristics and procedural details were compared between the dual-chamber mapping group and the conventional single-chamber mapping group. Results The number of RF applications (median [IQR]; 1.0 [1.0-3.0] vs. 3.0 [1.0-6.0], p = .0023), RF time (median [IQR], s; 9.2 [2.0-95.7] vs. 95.6 [4.1-248.7], p = .0107), and RF energy (median [IQR], J; 248.4 [58.7-3328.2] vs. 2867.6 [134.2-7728.4], p = .0115) were significantly lower in the dual-chamber group. The fluoroscopy time (median [IQR], min; 19.9 [14.2-26.1] vs. 26.5 [17.7-43.4], p = .0025) and fluoroscopy dose (median [IQR], mGy; 52.5 [31.3-146.0] vs. 119.0 [43.7-213.5], p = .0249) were also significantly lower in the dual-chamber than single-chamber mapping group. Conclusion The dual-chamber mapping was useful for ablating accessory pathways and reducing the number of RF applications, total RF energy, and radiation exposure as compared with traditional mapping techniques.

Introduction Detail 3D mapping have been useful for effective radiofrequency catheter ablation. Rhythmia system can create the atrio-ventricular dual chamber mapping, which reveals the atrial and ventricular potentials all at once in the same map. The aim of this study was to investigate the utility of Rhythmia system for catheter ablation of accessory pathways (AP). Methods From July 2015 to August 2020, 111 patients underwent ablation of APs. The dual chamber mappings were created in 50 patients [median age 15 (10-54), 32 male(64.0%)], while 61 patients underwent the radiofrequency (RF) ablations with conventional single chamber 3D mappings. The background characteristics and procedure details were compared between the dual chamber mapping group and conventional single chamber mapping group. Results The number of RF application [1 (1-3) vs 3 (1-6), p=0.0023], RF time [9.2 (2.0-95.7) vs 95.6 (4.1-248.7), p=0.0023], RF energy [248.4 (58.7-3328.2) vs 2867.6 (134.2-7728.4), p=0.0115] were significantly lower in dual chamber group. Fluoroscopy time [19.9 (14.2-26.1) vs 26.5 (17.7-43.4), p=0.0025], and fluoroscopy dose [52.5 (31.3-146.0) vs 119.0 (43.7-213.5), p=0.0249] were also significantly lower than in single chamber mapping group. Conclusion The dual chamber mappings were useful for effective ablation with reducing the radiation exposure.

Background The ablation index (AI) has been reported to be useful for a durable pulmonary vein isolation (PVI) to treat atrial fibrillation (AF). No study has reported the optimal AI value for the SVC isolation (SVCI). In this study, we aimed to investigate the optimal AI for the SVCI. Methods Thirty-six AF patients who underwent an initial SVCI were enrolled. Ablation was performed at a total of 549 points. The sites where dormant conduction was induced or additional ablation was needed were defined as touch-up sites (n=36). We compared the energy deliver time, power, CF, Force-Time Integral (FTI), and AI between the touch up sites and control sites (n=513). Results The median RF delivery time, power, CF, and FTI were all significantly lower at the touch up sites (touch up sites vs. control sites; energy delivery time, sec, 20.3[12.3-21.7] vs. 21.6[19.8-25.2], p=0.0003; power, W, 23.5[15-24] vs. 24[20-25], p

Supernormal antithrombin (AT) activity is rare in patients with sepsis. This study compared mortality rate of patients with sepsis and supernormal AT activity with that of other patients. This retrospective study included patients with sepsis from 42 intensive care units (ICUs) in Japan. Patients were included if their AT activity was measured on ICU admission, and if they did not receive AT concentrate. They were categorized into low, normal, and supernormal with respective AT activity of ≤70%, >70% to ≤100%, and >100%. The primary outcome was hospital in-patient mortality. Nonlinear regression analysis showed that mortality risk gradually increased with AT activity in the supernormal range, but without statistical significance. Survival rate was significantly lower in low (67%) and supernormal (57%) AT groups than in the normal AT group (79%; P < .001 and P = .008, respectively). After adjusting for disease severity and AT activity on day 2, supernormal AT activity was the only independent predictor of mortality. Sepsis with supernormal AT activity associated with high mortality, independent of disease severity, might be a predictor of in-hospital mortality.

The purpose of this study is to determine the outcome of foreign body airway obstruction according to the initial actions taken for choking victims during meals.Our subjects were patients who became unresponsive or unconscious because of foreign body airway obstruction (FBAO) during meals in the presence of bystander witnesses. We investigated the associations between outcome and the following factors: age, gender, type of foreign body, chest compressions after the patient became unresponsive or unconscious, episode of cardiac arrest, efforts by a bystander to remove the foreign body, eating-related activities of daily living, time elapsed from the 119 call to arrival of emergency medical technicians (EMTs), and time elapsed from the 119 call to hospital arrival (primary endpoint).Of the 138 patients enrolled during the study period, 35 (25.4%) received chest compressions by bystanders after becoming unresponsive or unconscious and 69 (50.0%) suffered cardiac pulmonary arrest. Chest compressions by a bystander after the victim became unresponsive or unconscious (p0.0001) and no CPA (p0.0001) were significantly related to good outcome. Chest compressions by a bystander were both associated with good neurological outcome (odds ratio, 10.57; 95% CI, 2.472-65.059, p0.0001). No CPA after FBAO was another independent predictor (odds ratio, 50.512; 95% CI, 13.45-284.41; p0.0001), but efforts to remove the foreign body before the arrival of EMTs did not affect outcome.Chest compressions by a bystander, a support received by only 25% of the patients, proved to be essential for improved outcome for choking victims who became unresponsive or unconscious. Education for lay-rescuer response to choking might further improve overall outcome.

Recently, Intelligent Transport Systems (ITS) technology have been intensively studied to solve environmental and energy problems by improving traffic flow. Along with the development of ITS and autonomous driving technologies, vehicle velocity control has to be considered for energy efficiency. In this paper, a minimum time autonomous driving (MTAD) system, which minimizes the traveling time considering energy constraint for an electric vehicle (EV), is proposed. The proposed method minimizes the traveling time by optimizing the velocity profile and front and rear driving-braking force distribution. The effectiveness of the proposed method is verified by simulations and bench tests.

Electric Vehicles (EVs) are deemed as an appealing and practical solution for environmental and energy problems. The mileage per charge of EVs, however, is shorter than the mileage of Internal Combustion Engine Vehicles (ICEVs). In this paper, Range Extension Autonomous Driving (READ) system considering road gradient information is proposed. The proposed system optimizes the velocity trajectory and the driving-braking force distribution ratio for autonomous driving. The authors carried out simulations and bench tests that prove the effectiveness of the proposal in terms of mileage per charge.

A 56-year-old woman with Graves' disease presented with the complaints of diarrhea and palpitations. Physical examination and laboratory data revealed hypothermia and signs of mild hyperthyroidism, heart failure, hepatic dysfunction with jaundice, hypoglycemia, and lactic acidosis. The patient was diagnosed as having developed the complication of thyroid storm in the absence of marked elevation of the thyroid hormone levels, because of the potential hepatic and cardiac dysfunctions caused by heavy alcohol drinking. A year later, after successful treatment, the patient remains well without any clinical evidence of heart failure or hepatic dysfunction. Thyroid storm associated with lactic acidosis and hypothermia is a serious condition and has rarely been reported. Prompt treatment is essential even if the serum thyroid hormone levels are not markedly elevated. We present a report about this patient, as her life could eventually be saved.

A variable valve timing mechanism has been applied in a high-speed direct injection diesel engine. The effective compression ratio ( εeff) is lowered by means of late intake valve closing, while keeping the expansion ratio constant. Premixed charge compression ignition (PCCI) combustion, adopting the Miller cycle, was experimentally realized and numerically analysed. Significant improvements in NO x (nitrogen oxides) and soot emissions were achieved for a wide range of engine speeds and loads frequently used in a transient mode test. The operating range of the Miller-PCCI combustion has been expanded up to an indicated mean effective pressure of 1.3 MPa.

A novel approach to reduce diesel engine emissions at relatively low injection pressures is proposed. This approach is based on the use of a mixed fuel where an additive or a low boiling point fuel such as CO2, gas fuel, or gasoline is mixed with a higher boiling point fuel such as diesel gas oil. When producing such a fuel, the vapour—liquid equilibrium in the two-phase region where the liquid and vapour phases of both components coexist is taken into account. In designing a mixed fuel, the authors intend to control both the physical process in the spray such as fuel evaporation and vapour air mixing and the chemical processes including spontaneous ignition and with reactions with regard to NO x, particulate matter (PM), and hydrocarbon (HC) formation. In this study flash boiling of mixed fuel is particularly focused on enhancing the mixing process in the spray because it has the potential to achieve fast evaporation and relatively lean and homogeneous mixtures. Experiments were carried out using two types of mixed fuel, both of which can generate flash boiling during injection events. In an experiment using a rapid compression machine (RCM) and an optical engine, mixed fuels consisting of liquefied CO2 as an additive and n-tridecane representing gas oil were employed with the aim of simultaneously reducting soot and NO x emissions. The high-speed images acquired for sprays reacting in the RCM and the engine clearly showed a significant reduction of soot formation in the spray. Reductions of soot and NO x emissions as well as the fuel consumption were also confirmed by emission measurements and a combustion analysis respectively. In other experiments, different types of mixed fuel consisting of gas or gasoline and gas oil were tested to see the effects on both the evaporation and ignition processes. The result of an engine experiment showed marked reductions of soot and HC emissions and fuel consumption.