Search

Transvenous lead extraction (TLE) is necessary because of system infection, lead malfunction, or system upgrade. Patients with severe left ventricular dysfunction (SLVD) undergoing TLE may be at a higher risk because hemodynamic parameters may change unfavorably during or after TLE; however, this has not yet been clarified.The purpose of this study was to examine whether patients with SLVD undergoing TLE have higher mortality.All patients who underwent TLE were stratified as follows: patients with ejection fraction ≤ 35% (SLVD group) and those with ejection fraction35% (non-SLVD group).We assessed the data of 200 patients [SLVD group, 36 (18%); non-SLVD group, 164 (82%)]). Brain natriuretic peptide level and cardiac resynchronization therapy rate were higher in the SLVD group than in the non-SLVD group. There were no significant between-group differences in major complications and clinical success rates. Patients with SLVD were more likely to require additional hemodynamic support, such as catecholamine infusion, temporary atrium-ventricle sequential pacing, and temporary cardiac resynchronization therapy pacing (27.8% vs 1.2%; P.001). The survival rate was not significantly different between the groups at 30 days and 1 year after TLE (SLVD vs non-SLVD: 30 days: 97.2% vs 99.4%; P = .215; 1 year: 80.6% vs 91.5%; P = .053). Multivariate Cox regression analysis revealed log brain natriuretic peptide and serum hemoglobin levels as predictors for 1-year mortality.The prognosis after TLE was comparable between patients with and without SLVD. However, additional hemodynamic support was often necessary for patients with SLVD.

Early treatment with an oral β-blocker is recommended in patients with a ST-segment-elevation myocardial infarction (STEMI). In this multicenter study, we evaluated the effects of a continuous administration of landiolol, an ultrashort-acting β-blocker, before primary percutaneous coronary intervention (PCI) on myocardial salvage and its safety in STEMI patients. A total of 47 Japanese patients with anterior or lateral STEMI undergoing a primary PCI within 12 h of symptom onset were randomized to receive intravenous landiolol (started at 3 μg/min/kg dose and continued to a total of 50 mg; n=23) or not (control; n=24). Patients with Killip class III or more were excluded. The primary outcome was the myocardial salvage index on cardiac magnetic resonance imaging (MRI) performed 5-7 days after the PCI. Cardiac MRI was performed in 35 patients (74%). The myocardial salvage index in the landiolol group was significantly greater than that in the control group (44.4±14.6% vs. 31.7±18.9%, respectively; p=0.04). There were no significant differences in adverse events at 24 h between the landiolol and control groups. A continuous administration of landiolol before a primary PCI may increase the degree of myocardial salvage without additional hemodynamic adverse effects within the first 24 h after STEMI.

Background The incidence of ventricular tachycardia (VT) in patients following Fontan operation is reported as 3.5%. Furthermore, in patients with repaired double outlet right ventricle (DORV), scar-related VT and outflow tract VT have been reported; however, Purkinje-related VT has not previously been reported. In this report, we present the case of idiopathic left VT (ILVT) in a patient with DORV who underwent Fontan operation. Case summary A 31-year-old man was diagnosed as having DORV with complete atrioventricular defect at birth. When he was 17 years old, he underwent surgical repair, including extracardiac Fontan operation and common atrioventricular valve replacement. Five years later, VT was detected. Since some medications were ineffective in suppressing VT, he was referred to our hospital for definitive treatment. Ventricular tachycardia was induced by atrial and ventricular programmed electrical stimulations. The mechanism of the VT was determined to be re-entry. The earliest activation site was located at the mid-inferior septum of the hypoplastic left ventricle, in which Purkinje potentials were observed before the local ventricular electrogram. Radiofrequency catheter ablation (RFCA) was performed at this site to eliminate VT. Discussion Most VTs originate from surgical scars in patients with congenital heart disease. Catheter ablation was feasible in scar-related VT. To the best of our knowledge, this is the first report of ILVT treated successfully with RFCA in a DORV patient who had undergone Fontan operation.

Aims To establish the indication for programmed ventricular stimulation (PVS) for asymptomatic patients with Brugada syndrome (BrS), we evaluated the prognostic significance of PVS based on abnormal electrocardiogram (ECG) markers. Methods and results One hundred and twenty-five asymptomatic patients with BrS were included. We performed PVS at two sites of the right ventricle with up to three extrastimuli [two pacing cycle lengths and minimum coupling interval (MCI) of 180 ms]. We followed the patients for 133 months and evaluated ventricular fibrillation (VF) events. Fragmented QRS (fQRS) and Tpeak-Tend (Tpe) interval were evaluated as ECG markers for identifying high-risk patients. Fragmented QRS and long Tpe interval (≥100 ms) were observed in 66 and 37 patients, respectively. Ventricular fibrillation was induced by PVS in 60 patients. During follow-up, 10 patients experienced VF events. Fragmented QRS, long Tpe interval, and PVS-induced VF with an MCI of 180 ms or up to two extrastimuli were associated with future VF events (fQRS: P = 0.015, Tpe ≥ 100 ms: P = 0.038, VF induction: P < 0.001). However, PVS-induced VF with an MCI of 200 ms was less specific (P = 0.049). The frequencies of ventricular tachyarrhythmia events during follow-up were 0%/year with no ECG markers and 0.1%/year with no VF induction. The existence of two ECG factors with induced VF was strongly associated with future VF events (event rate: 4.4%/year, P < 0.001), and the existence of one ECG factor with induced VF was also associated (event rate: 1.3%/year, P = 0.011). Conclusion We propose PVS with a strict protocol for asymptomatic patients with fQRS and/or long Tpe interval to identify high-risk patients.

Left atrial appendage (LAA) size is crucial for determining the indication of transcatheter LAA closure. The aim of this study was to evaluate the differences in LAA morphology according to the types of atrial fibrillation (AF). A total of 340 patients (mean age: 65 ± 15 years) who underwent transesophageal echocardiography (TEE) were included. Patients were classified into non-AF (n = 105), paroxysmal AF (n = 86), persistent AF (n = 87), or long-standing persistent AF (n = 62). LAA morphology, including LAA ostial diameter and depth, was assessed using TEE. Patients with long-standing persistent AF had larger LAA ostial diameter and depth, greater LAA lobes, and lower LAA flow velocity. The maximum LAA ostial diameter was 19 ± 4 mm in patients with non-AF, 21 ± 4 mm in patients with paroxysmal AF, 23 ± 5 mm in patients with persistent AF, and 26 ± 5 mm in patients with long-standing persistent AF. LAA ostial diameter was increased by 2 or 3 mm with the progression of AF. LAA ostial diameter was correlated with LA volume index (R = 0.37, P < 0.01) and the duration of continuous AF (R = 0.30, P < 0.01), but not with age or the period from the onset of AF. LAA size, which is the determinant for selecting device size of transcatheter LAA closure, was increased with the progression of AF. Our findings have potential implications for therapeutic strategy of transcatheter LAA closure.

Objective Remote monitoring (RM) of cardiac implantable electric devices (CIEDs) has been advocated as a healthcare standard. However, expert consensus statements suggest that all patients require annual face-to-face follow-up consultations at outpatient clinics even if RM reveals no episodes. The objective of this study was to determine the critical event rate after CIED implantation through RM. Methods This multicenter, retrospective, cohort study evaluated patients with pacemakers (PMs), implantable cardioverter defibrillators (ICDs), or cardiac resynchronization therapy defibrillator (CRT-Ds) and analyzed whether or not the data drawn from RM included abnormal or critical events. Patients A total of 1,849 CIED patients in 12 hospitals who were followed up by the RM center in Okayama University Hospital were included in this study. Results During the mean follow-up period of 774.9 days, 16,560 transmissions were analyzed, of which 11,040 (66.7%) were abnormal events and only 676 (4.1%) were critical events. The critical event rate in the PM group was significantly lower than that in the ICD or CRT-D groups (0.9% vs. 5.0% or 5.9%, p

Background The increase in the use of cardiac implantable electronic devices (CIEDs) has been associated with an increase in CIED‐related infections. Transvenous lead extraction is safe and effective for patients with CIED‐related infections; however, the mortality rate in these patients is high. The prognosis after transvenous lead extraction in Japanese patients, especially those with lead‐related infective endocarditis, has not been evaluated. Then, the purpose of this study is to clarify the prognosis after transvenous lead extraction in Japanese patients with CIED‐related infections at a single Japanese center. Methods A total of 107 patients who underwent transvenous lead extraction were retrospectively reviewed. The patients were divided into a lead‐related infective endocarditis group (n = 32) and a pocket infection group (n = 75). Procedure success rate and prognosis after lead extraction were evaluated between the two groups. Results Procedure success rate was not significantly different between the groups. There were no deaths associated with the procedure or with infection. The survival rate was not significantly different at 1 year or at a median of 816 days (lead‐related infective endocarditis vs pocket infection; 93.7% vs 94.7%, P = 1.000; 78.1% vs 81.3%, P = 0.791) Time to reimplantation and duration of hospital stay and antibiotics therapy were significantly longer for patients with lead‐related infective endocarditis. Conclusion In this study, the prognosis for patients with lead‐related infective endocarditis after transvenous lead extraction was favorable. Thus, extraction should be strongly recommended, even if the general condition of the patient is poor.

Purpose High-risk patients can be identified by preprocedural computed tomography (CT) before lead extraction. However, CT evaluation may be difficult especially for lead tip identification due to artifacts in the leads. Selective right ventriculography (RVG) may enable preprocedural evaluation of lead perforation. We investigated the efficacy of RVG for identifying right ventricular (RV) lead perforation compared with CT in patients who underwent lead extraction. Methods Ninety-five consecutive patients who were examined by thin-section non-ECG-gated multidetector CT and RVG before lead extraction were investigated retrospectively. Newly recognized pericardial effusion after lead extraction was used as a reference standard for lead perforation. We analyzed the prevalence of RV lead perforation diagnosed by each method. The difference in the detection rates of lead perforation by RVG and CT was evaluated. Results Of the 115 RV leads in the 95 patients, lead perforation was diagnosed for 35 leads using CT, but the leads for 29 (83%) of those 35 leads diagnosed as lead perforation by CT were shown to be within the right ventricle by RVG. Three patients with 5 leads could not be evaluated by CT due to motion artifacts. The diagnostic accuracies of RVG and CT were significantly different (p < 0.001). There was no complication of pericardial effusion caused by RV lead extraction. Conclusion RVG for identification of RV lead perforation leads to fewer false-positives compared to non-ECG-gated CT. However, even in cases in which lead perforation is diagnosed, most leads may be safely extracted by transvenous lead extraction.

Background Sinus tachycardia during exercise attenuates ST‐segment elevation in patients with Brugada syndrome, whereas ST‐segment augmentation after an exercise test is a high‐risk sign. Some patients have premature ventricular contractions (PVCs) related to exercise, but the significance of exercise‐related PVCs in patients with Brugada syndrome is still unknown. The objective of this study was to determine the significance of exercise‐related PVCs for predicting occurrence of ventricular fibrillation (VF) in patients with Brugada syndrome. Methods and Results The subjects were 307 patients with Brugada syndrome who performed a treadmill exercise test. We evaluated the occurrence of PVCs at rest, during exercise and at the peak of exercise, and during recovery after exercise (0–5 minutes). We followed the patients for 92±68 months and evaluated the occurrence of VF. PVCs occurred in 82 patients (27%) at the time of treadmill exercise test: PVCs appeared at rest in 14 patients (4%), during exercise in 60 patients (20%), immediately after exercise (0–1.5 minutes) in 28 patients (9%), early after exercise (1.5–3 minutes) in 18 patients (6%), and late after exercise (3–5 minutes) in 12 patients (4%). Thirty patients experienced VF during follow‐up. Multivariable analysis including symptoms, spontaneous type 1 ECG, and PVCs in the early recovery phase showed that these factors were independently associated with VF events during follow‐up. Conclusions PVCs early after an exercise test are associated with future occurrence of VF events. Rebound of vagal nerve activity at the early recovery phase would promote ST‐segment augmentation and PVCs in high‐risk patients with Brugada syndrome.

Background Previous clinical studies showed that early intravenous metoprolol before reperfusion in patients with ST-elevation myocardial infarction (STEMI) undergoing primary PCI reduced infarct size. However, intravenous beta-blockers in acute phase of STEMI can be associated with adverse effects such as cardiogenic shock and atrioventricular block. Landiolol is an ultrashort-acting beta-blocker with a half-life of 3 min that is eight times more cardioselective than esmolol. Purpose We evaluate the efficacy of intravenous infusion of landiolol on infarct size and its safety in STEMI patients undergoing primary PCI. Methods This study is a multicenter randomized control trial. A total of 47 patients with Killip class II or less STEMI undergoing PCI within 12 hours of symptoms onset were randomized to receive intravenous landiolol (n=23) or not (control, n=24). Patients allocated to landiolol group delivered an intravenous continuous dose of 3μg/min/kg before reperfusion and then continued until a total dose of 50mg. All patients started oral metoprolol or carvedilol within 12 hours. The primary end point was myocardial salvage index (MSI) on magnetic resonance imaging performed 5 to 7 days after PCI. MSI was defined as the difference between the area at risk and the area of necrosis analyzed using a commercial software. Results Magnetic resonance imaging was performed in 35 patients (17 patients in landiolol group and 18 patients in the control group), and ischemia duration time was 229 minutes in the landiolol group and the 242 minutes in control. In adjusting for confounding variables, the areas of myocardium at risk were not difference in both groups (54.4g in the landiolol group, and 46.8g in the control group; p=0.31). However, MSI in the landiolol group was significantly reduced than that in the control group (36.8% and 57.0%; p In both group blood pressure was not difference in recruitment (142mmHg in landiolol group, and 144 in control) and starting PCI (163mmHg in landiolol group, and 165 in control). Regarding safety, the composite of death, malignant ventricular arrhythmia, cardiogenic shock, and atrioventricular block at 24 hours did not differ between the landiolol and the control groups (8.7% and 8.3%, respectively, p=0.93). Conclusion Early intravenous landiolol before starting primary PCI reduced infarct size in STEMI patients without significant hemodynamic adverse effects. Funding Acknowledgement Type of funding source: None

Background Given that amyloid-β (Aβ) peptide is produced and released at synapses, synaptic Aβ is one of the promising therapeutic targets to prevent synaptic dysfunction in Alzheimer's disease (AD). Although Aβ production begins with the cleavage of the amyloid-β protein precursor (AβPP) by β-site AβPP cleaving enzyme 1 (BACE1), the mechanism on how BACE1 is involved in AβPP processing at synapses remains unclear. Objective This study aimed to identify novel BACE1 interacting proteins regulating Aβ production at the synapse. Methods BACE1 interacting proteins were pulled down using a mass spectrometry-based proteomics of wild-type (WT) rat brain synaptoneurosome lysates utilizing anti-BACE1 antibody. Then, a novel BACE1 interactor was identified and characterized using experimental systems that utilized transfected cells and knockout (KO) mice. Results Synaptic vesicle protein 2B (SV2B) was identified as a novel presynaptic interaction partner of BACE1. In HEK293 cells, co-overexpression of SV2B with BACE1 significantly reduced the sAβPPβ and Aβ levels released in the media; thus, SV2B overexpression negatively affected the AβPP cleavage by BACE1. Compared with those of WT mice, the hippocampal lysates of SV2B knockout mice had significantly elevated Aβ levels, whereas the β-secretase activity and the AβPP and BACE1 protein levels remained unchanged. Finally, a fractionation assay revealed that BACE1 was mislocalized in SV2B KO mice; hence, SV2B may be involved in BACE1 trafficking downregulating the amyloidogenic pathway of AβPP. Conclusion SV2B has a novel role of negatively regulating the amyloidogenic processing of AβPP at the presynapses.

We have been developing a LTS superconducting quantum interference device (SQUID) magnetometer system aiming at highly sensitive geomagnetic field measurements with an intended magnetic field noise floor of approximately 10 fT/√Hz in the frequency range below 100 Hz. However, our previous system using SQUID magnetometers with the noise of ∼30 fT/√Hz had the system noise of ∼200 fT/√Hz, and the measurable frequency bandwidth was limited up to ∼30 Hz. This unsatisfactory performance was due to the thermal noise and cutoff frequency of an electromagnetic (EM) shield made of copper foil, which covered the SQUID magnetometers cylindrically, because its design was not optimum. To improve the instrument performance, we fabricated SQUID magnetometers having a noise floor of ∼10 fT/√Hz. We also evaluated the thermal noise and cutoff frequency of pure copper foils with different values of thickness and purity. Adopting a 0.08-mm-thick copper foil as an EM shield for the new SQUID magnetometers, the system noise and frequency bandwidth were improved to ∼25 fT/√Hz and ∼1 kHz, respectively. Using this improved system, we measured geomagnetic fields and confirmed that the background signal in the Z component was smaller compared with the measurement result obtained using the previous system.

Introduction New onset of ventricular fibrillation (VF) in asymptomatic patients with Brugada-type ECG is not frequent, but it cannot be negligible. Risk markers for predicting VF are usually based on results of analysis in symptomatic patients, and they have not been determined for asymptomatic patients. We analyzed ECG markers in patients with Brugada syndrome to differentiate the risk factors for VF in both symptomatic and asymptomatic patients. Methods The subjects were 471 patients with Brugada syndrome and we divided the subjects into two groups: Asymptomatic group (n = 326) and Symptomatic group (syncope: n = 122, VF: n = 23). We analyzed the following ECG markers: RR, PQ, QRS, QT and Tpeak-Tend (Tpe) intervals, ST level, atrial fibrillation (AF), atrioventricular block, spontaneous type 1 ECG, early repolarization (ER) and fragmented QRS (fQRS). Results During follow-up (91±64 months), 41 patients experienced VF (Asymptomatic: n = 10, Symptomatic: n = 31). Univariable analysis showed that spontaneous type 1 ECG, Tpe interval (≥95 ms), high ST level (≥0.52 mV) and fQRS were common predictors for VF in both the Asymptomatic and Symptomatic groups. In addition to the common risk factors, wide QRS (≥107 ms), long QT interval (≥420 ms), ER and AF were predictors for VF in Symptomatic group. Multivariable analysis of the Symptomatic group showed fQRS, Tpe and ER were independent predictors of prognosis. Conclusions fQRS and Tpe interval are common risk factors for VF in both asymptomatic and symptomatic patients, whereas ER is a predictor for recurrent VF. This article is protected by copyright. All rights reserved

We have developed a high-spatial-resolution superconducting quantum interference device (SQUID) microscope for magnetic field imaging of rock samples at room temperature, using a hollow-structured cryostat. A directly coupled low-temperature SQUID with a $200\ \mu\text{m} \times 200\ \mu\text{m}$ pickup loop, which is mounted on a sapphire conical rod, is separated from room temperature by a thin sapphire window. Precise and repeatable adjustment of the vacuum gap between the SQUID and the sapphire window is performed by rotating a micrometer spindle connected to the sapphire rod through the hollow portion of the cryostat. A spacing of 230 $\mu\text{m}$ between the SQUID and a sample has been achieved. We demonstrated the imaging of the magnetic field on a zircon containing magnetic grains.

Neurolymphomatosis (NL) is a rare condition involving the infiltration of lymphoma cells into the peripheral nervous system. NL can be primary or secondary in the setting of an unknown or known hematologic malignancy, respectively. Here, we report five cases in which F-18 2-fluoro-2-deoxy-glucose positron emission tomography/computed tomography (F-18 FDG-PET/CT) had great value for diagnosing NL. Two cases were rare primary NL, and the other three were secondary NL. Clinical presentations were asymmetric sensorimotor disturbances in the extremities with or without involvement of cranial nerves. Furthermore, all patients experienced spontaneous pain in the face or affected extremities. Cerebrospinal fluid analysis was cytologically negative in two of five cases. Gadolinium (Gd)-enhanced magnetic resonance imaging (MRI) detected abnormalities in the cranial nerves, nerve roots, and cauda equina in all cases except case 1 and the recurrent stage of case 2. F-18 FDG-PET/CT showed clear visualization of almost all the lymphomatous involvement of peripheral nerves and other tissues in all patients. Furthermore, F-18 FDG-PET/CT detected abnormalities including asymptomatic lesions that were not detected with MRI, and also identified the appropriate lesion for diagnostic biopsy. However, as in case 3, the lesions in the left oculomotor nerve and the cauda equina were detected only with Gd-enhanced MRI, which has superior spatial resolution. In conclusion, F-18 FDG-PET/CT is a sensitive modality that can suggest the presence of malignancy and identify appropriate places for diagnostic biopsies. It is especially useful when combined with Gd-enhanced MRI, even in patients with primary NL that is usually difficult to diagnose.

We present developments and applications of a high resolution scanning superconducting quantum interference device (SQUID) microscope for imaging magnetic field of geological samples at room temperature. A directly coupled low-temperature SQUID with a 200 μm × 200 μm pickup loop was mounted on a sapphire rod and separated from room temperature by a sapphire window. The environmental noise of the SQUID was successfully reduced by subtracting the signal of an additional reference SQUID placed inside a cryostat. The resulting system noise level was estimated to be about 50 pT. A geological thin section could be placed on a non-magnetic sample holder with an XYZ stage for scanning in an area of 100 mm × 100 mm. The minimum achievable distance from the SQUID to the sample is measured as ∼200 µm. An application of the SSM to a marine ferromanganese crust successfully provided beautiful stripe patterns in the magnetic images. The patterns could be correlated to the history of geomagnetic field reversals. The boundaries of the magnetic polarity domains were useful guides for the estimation of the deposition age by correlation with the standard geomagnetic polarity timescale. The established age model gave an average growth rate of ∼2.7 mm/Ma, which is consistent with that obtained by radiometric dating using 10Be (∼2.6 mm/Ma).

Various risk stratifications in asymptomatic patients with Brugada syndrome (BrS) have been proposed, but the electrophysiological change that promotes ventricular fibrillation (VF) is still unknown.The aim of this study was to clarify the changes in electrocardiographic (ECG) markers at the onset of VF from ECGs recorded when patients were still asymptomatic.The subjects of this study included 14 patients with VF and 48 consecutive asymptomatic patients with BrS. We compared ECGs before the initial VF events (6 months; early phase) with ECGs at the initial VF events (late phase). In asymptomatic patients, we evaluated ECGs at 2 time points with an interval of6 months. We evaluated various ECG markers including type 1 ECG and fragmented QRS (fQRS; multiple spikes within the QRS complex).ECG parameters of the early and late phases were not different except for decreased ST voltage and low incidence of type 1 ECG in asymptomatic patients. There were no differences in ECG parameters of the early phase between patients with VF and asymptomatic patients. In patients with VF, ECGs at the late phase had longer QRS intervals and intervals between the peak and the end of the T wave and more frequent type 1 ECG and fQRS than did ECGs at the early phase. Those changes were associated with initial VF events (QRS widening: odds ratio [OR] 11.5, P.01; interval between the peak and the end of the T wave: OR 11.6, P.01; fQRS: odds ratio 15.3, P.01; type 1 ECG: OR 6.6, P.05).QRS and ST-T wave abnormalities developed in association with the initial VF events. Aggravation of the conduction disturbance in addition to BrS-ECG promotes VF.

The deposition of Amyloid-beta peptides (Aβ) is detected at an earlier stage in Alzheimer’s disease (AD) pathology. Thus, the approach toward Aβ metabolism is considered to play a critical role in the onset and progression of AD. Mounting evidence suggests that lifestyle-related diseases are closely associated with AD, and exercise is especially linked to the prevention and the delayed progression of AD. We previously showed that exercise is more effective than diet control against Aβ pathology and cognitive deficit in AD mice fed a high-fat diet; however, the underlying molecular mechanisms remain poorly understood. On the other hand, a report suggested that exercise induced expression of fibronectin type III domain-containing protein 5 (FNDC5) in the hippocampus of mice through PGC1α pathway. Thus, in the current study, we investigated a possibility that FNDC5 interacts with amyloid precursor protein (APP) and affects Aβ metabolism. As a result, for the first time ever, we found the interaction between FNDC5 and APP, and forced expression of FNDC5 significantly decreased levels of both Aβ40 and Aβ42 secreted in the media. Taken together, our results indicate that FNDC5 significantly affects β-cleavage of APP via the interaction with APP, finally regulating Aβ levels. A deeper understanding of the mechanisms by which the interaction between APP and FNDC5 may affect Aβ production in an exercise-dependent manner would provide new preventive strategies against the development of AD. Electronic supplementary material The online version of this article (10.1186/s13041-018-0401-8) contains supplementary material, which is available to authorized users.

Background Remote monitoring (RM) has been advocated as the new standard of care for patients with cardiovascular implantable electronic devices (CIEDs). RM has allowed the early detection of adverse clinical events, such as arrhythmia, lead failure, and battery depletion. However, lead failure was often identified only by arrhythmic events, but not impedance abnormalities. Objective To compare the usefulness of arrhythmic events with conventional impedance abnormalities for identifying lead failure in CIED patients followed by RM. Methods CIED patients in 12 hospitals have been followed by the RM center in Okayama University Hospital. All transmitted data have been analyzed and summarized. Results From April 2009 to March 2016, 1,873 patients have been followed by the RM center. During the mean follow-up period of 775 days, 42 lead failure events (atrial lead 22, right ventricular pacemaker lead 5, implantable cardioverter defibrillator [ICD] lead 15) were detected. The proportion of lead failures detected only by arrhythmic events, which were not detected by conventional impedance abnormalities, was significantly higher than that detected by impedance abnormalities (arrhythmic event 76.2%, 95% CI: 60.5-87.9%; impedance abnormalities 23.8%, 95% CI: 12.1-39.5%). Twenty-seven events (64.7%) were detected without any alert. Of 15 patients with ICD lead failure, none has experienced inappropriate therapy. Conclusions RM can detect lead failure earlier, before clinical adverse events. However, CIEDs often diagnose lead failure as just arrhythmic events without any warning. Thus, to detect lead failure earlier, careful human analysis of arrhythmic events is useful.

We have developed a high-resolution scanning superconducting quantum interference device (SQUID) microscope for imaging the magnetic field of geological samples at room temperature. In this paper, we provide details about the scanning SQUID microscope system, including the magnetically shielded box (MSB), the XYZ stage, data acquisition by the system, and initial evaluation of the system. The background noise in a two-layered PC permalloy MSB is approximately 40–50 pT. The long-term drift of the system is approximately ≥1 nT, which can be reduced by drift correction for each measurement line. The stroke of the XYZ stage is 100 mm × 100 mm with an accuracy of ~10 µm, which was confirmed by laser interferometry. A SQUID chip has a pick-up area of 200 µm × 200 µm with an inner hole of 30 µm × 30 µm. The sensitivity is 722.6 nT/V. The flux-locked loop has four gains, i.e., ×1, ×10, ×100, and ×500. An analog-to-digital converter allows analog voltage input in the range of about ±7.5 V in 0.6-mV steps. The maximum dynamic range is approximately ±5400 nT, and the minimum digitizable magnetic field is ~0.9 pT. The sensor-to-sample distance is measured with a precision line current, which gives the minimum of ~200 µm. Considering the size of pick-up coil, sensor-to-sample distance, and the accuracy of XYZ stage, spacial resolution of the system is ~200 µm. We developed the software used to measure the sensor-to-sample distance with line scan data, and the software to acquire data and control the XYZ stage for scanning. We also demonstrate the registration of the magnetic image relative to the optical image by using a pair of point sources placed on the corners of a sample holder outside of a thin section placed in the middle of the sample holder. Considering the minimum noise estimate of the current system, the theoretical detection limit of a single magnetic dipole is ~1 × 10-14 Am2. The new instrument is a powerful tool that could be used in various applications in paleomagnetism such as ultrafine-scale magnetostratigraphy and single-crystal paleomagnetism.

In the case of most physiological tissues, longitudinal relaxation time (T1) depends on the applied magnetic field strength, and the T1-contrast between different types of tissues can be enhanced at low magnetic fields. Prepolarized SQUID-based MRI could be used to perform T1-weighted imaging at low fields. We aimed to develop a low-field MRI system that can provide clear T1-weighted images. The system consists of five sets of coils for generating magnetic fields required for generating the NMR/MRI signal and a first-order SQUID gradiometer for detecting free induction decay (FID) signals from a sample. We improved the polarizing-field-driving circuit to increase the field, and developed the SQUID-driving electronics to reduce the artifacts in the increased polarizing field. Using this system, we measured T1 of water–oil mixture sample. Clear T1 spectrum of each ingredient of the sample was obtained by CONTIN analysis.

Superconducting quantum interference device (SQUID)-based spinal cord evoked magnetic field (SCEF) measurement systems are being developed for the diagnosis of spinal cord diseases such as myelopathy. Previous papers have reported several SQUID magnetometers optimized for the detection of the magnetic field evoked by axonal nerve activity at the neck of subjects in sitting or supine positions, thus enabling noninvasive functional imaging of the cervical spinal cord. In this study, we implemented two improvements in the SQUID SCEF system to extend its application range and to make it suitable for practical use in hospitals. One was a newly designed cryostat that was implemented in order to apply the SCEF measurement not only to the cervical region but also to wider regions such as the lumbar or sacral regions. The other improvement was the implementation of SQUID driving electronics to detect not only conventional fast SCEF components accompanied by action potentials but also slow SCEF components resulting from postsynaptic activity. We also implemented direct flux feedback using a set of reference sensors composed of three SQUID magnetometers arranged in an orthogonal orientation in order to reduce noise. We then performed an SCEF measurement using the improved system and successfully observed the distribution of the magnetic field from the sacral region with a peak amplitude of less than 10 fT.

An LTS SQUID biomagnetometer system was developed for the non-invasive diagnosis method of the spinal cord function for orthopedic and neurologic application. The developed biomagnetometer system is characterized by a uniquely shaped cryostat. It has a vertical cylinder-shaped main body and a protrusion from its side surface. An array of SQUID vector gradiometers with a 5 times 8 matrix-like arrangement for 90 mm times 140 mm observation area is installed in the protrusion. Supine subjects are able to fit their cervixes stably to the sensor array by putting them against the protrusion during the measurement. The sensors directed vertically upwards detect magnetic signals from the back of the cervix. An X-ray imaging apparatus is integrated to the SQUID system for the in-situ acquisition of the anatomical information that reveals the position of cervical vertebrae relative to the location of the sensor array. For the performance verification of the developed system, we examined the spinal cord evoked field measurement of a normal subject. We succeeded in observing the transition of the cervical magnetic field distribution induced by the electric pulse stimulation on the median nerve at the subject's wrist.

We are investigating an application of the biomagnetic measurement to non-invasive diagnosis of spinal cord function. Multichannel superconducting quantum interference device (SQUID) biomagnetometer systems for the measurement of the evoked magnetic field from spinal cords were developed as hospital-use apparatuses. The specific pattern transition of the spinal cord evoked field distribution was clearly observed. The conduction velocity of the cervical spinal cord, which is a significant information for the diagnosis of the dysfunction, was non-invasively estimated from the magnetic measurement.

Objectives: We evaluated the predictors of recurrent restenosis and the impact of lesion length and vessel size on outcomes in patients treated with routine sirolimus-eluting stent (SES) implantation for in-stent restenosis (ISR) of bare-metal stent (BMS). Methods: In this study, 250 consecutive patients with 275 lesions after SES implantation for ISR of BMS were enrolled. Follow-up angiogram was obtained in 239 patients with 258 lesions eight months after implantation (follow-up rate: 95.6%). We compared characteristics of patients and lesions between the two groups (the recurrent restenosis group and the no-restenosis group). Results: Recurrent restenosis was angiographically documented in 43 lesions (16.7%). Recurrent restenosis was found in 30.4% with small vessel lesions (reference diameter of less than 2.5 mm, 92 lesions) and 23% with the diffuse type lesions (106 lesions). Seventy-two per cent of patients had a focal pattern of recurrent restenosis. Previously recurrent ISR lesions (odds ratio (OR) 1.94, 95% confidence interval (CI) 0.94 to 4.06, p = 0.05), reference diameter of less than 2.5 mm (OR 2.41, CI 1.05 to 5.41, p = 0.03), diffuse type restenosis (OR 4.48, CI 2.12 to 9.94, p = 0.0001) and dialysis patients (OR 4.72, CI 1.42 to 15.7, p = 0.01) were independent predictors of recurrent restenosis. Conclusions: Small vessels, diffuse type restenosis and dialysis patients were still the predictors of recurrent restenosis in patients treated with SES for ISR of BMS.

A 75-ch SQUID biomagnetometer system for the measurement of the cervical spinal cord evoked magnetic field (SCEF) was developed for the purpose of the noninvasive functional diagnosis of the spinal cord. The sensor array has 25 SQUID vector sensors arranged along the cylindrical surface to fit to the shape of the subject's neck. The magnetic fields, not only in the direction radial to the subject's body surface but also in the tangential direction, are observed in the area of 80 mm times 90 mm at one time. The dewar has a unique shape with a cylindrical main body and a protrusion from its side surface. The sensor array is installed in the protruded part. This design is optimized to detect magnetic signals at the back of the neck of the subject sitting in a reclining position. We applied the developed SQUID system to the cervical SCEF measurement of normal subjects who were given electric pulse stimulation to their median nerves at the wrists. The evoked magnetic signals were successfully detected at the cervixes of all subjects. A characteristic pattern of transition of the SCEF distribution was observed as a reproducible result and the signal components propagating along the spinal cord were found in the time varying SCEF distribution. We expect that the investigation of the propagating signal components would help to establish a noninvasive functional diagnosis of the spinal cord.

Accurate measurement of the biomagnetic signals from a rat or a mouse crucially benefits the development of new medicines and pathologies. In previous studies, MEG/MCG systems developed for humans were used to obtain small animal biomagnetic signals, but we only partially succeeded. The accuracy and efficiency of the results were insufficient because the systems were not designed to measure small animal MEG or MCG. In order to improve the efficiency and accuracy of small animal measurements, we have developed a biomagnetism measurement system suitable for small animals. The newly developed integrated 9ch Low-Tc SQUIDs magnetometer array is designed to improve spatial resolution. It has a 2.5 mm diameter pickup coil on each sensor and covers 8 mm × 8 mm measurement area. A single measurement by the sensor provides sufficient data for the analysis of small animal biosignals. Measurement efficiency and replicability has also been improved compared to conventional systems by the addition of a removable table and the 3-axis linear stage. The removable nonmagnetic table is attached to a 3-axis linear stage and its temperature is controlled by circulating hot water in order to keep subject stable while recording. The principal components of this system are integrated into a small transportable chassis. The dimension of the whole system is 1.4 m in width, 0.7 m in depth, 1.8 m in height. The small sized biomagnetism measurement system is easy to place in a typical lab space.

We designed and fabricated a 9-channel magnetometer array probe with low noise and high spatial resolution for magnetocardiograph (MCG) measurements of mice and rats. The magnetometer based on a low-Tc superconducting interference device (SQUID) has a circular pick-up loop with the diameter of 2.5 mm and is arrayed in a 3 × 3 matrix with the spatial interval of 2.75 mm on a 10 mm × 10 mm silicon chip. The chip was mounted on a glass epoxy substrate with the diameter of 19 mm using flip-chip connections so that the cross talk due to wiring is reduced as small as possible. To protect the array during repetitive thermal cycles, the chip is covered with an epoxy resin. Typical field resolution of the array was 8 fT/√Hz at 1 kHz and the maximum cross talk in the array was measured to be less than 2%. Setting up this probe in a small cryostat with the warm-to-cool distance of about 2 mm, we demonstrated a real-time monitoring of MCG signals from a mouse and a rat in a magnetically shielding.

Chained current element (CCE) analysis is a new approach of magnetic source analysis for the spinal cord evoked field (SCEF) measurements. In the CCE analysis, magnetic sources are described by multiple dipoles arranged along a parameterized curve that corresponds to a modelled spinal cord. Both path of the neural signal propagation and the current distribution along the path are determined at once by searching the parameters that determine the shape and position of the curve. We applied the CCE analysis to the data from an actual SCEF measurement on a rabbit. The possibility of the lesion localization of the spinal cord by the CCE analysis was indicated.

MEG phantoms with saline water, as a practical realization of the Sarvas model, have been used to evaluate the accuracy of magnetic field measurement from MEG systems as well as to confirm the validity of algorithms for magnetic source analysis. But there are several concerns to be addressed before they will be accepted as “the evaluation standard.” The concerns are that mechanical accuracy is hard to achieve, linear current drive is also hard to achieve and that electrode quality degrades easily. On the other hand, “dry phantom” proposed by Ilmoniemi et al., which is an isosceles-triangle coil with an infinitely small base, is free from these concerns and is a promising candidate for the standard. To realize a practical standard with this model, the base should be finite. So, we calculated the magnetic field from a finite-small base isosceles-triangle coil in comparison with the magnetic field of the ideal Sarvas model. Calculations were done for 80-mm legs with 10-mm base triangle and for 80-mm legs with 5-mm base triangle, which results in maximum 2% error and maximum 0.2% error from the ideal Sarvas model, respectively. These results suggest that the isosceles-triangle coil with a 5-mm base is a good selection for the standard phantom.

We examined the non-linear impedance of a saline water phantom using a prototype with 150-mm diameter sphere and with 5-mm dipole electrodes located at 20 mm from the center of the sphere. We found that the electrical impedance is a series of 0.84-μF capacitor and 250-Ω resistor, which requires unpractical source impedance and voltage, 1.9 MΩ and 760 V respectively, to drive the phantom without distortion. Also observed was a non-linearity due to the electrolysis, which can be avoided by constraining the frequency to be more than 1 kHz, in which frequency human brain signal is not properly emulated. Due to these difficulties, the phantom with saline water is not a good candidate for “the evaluation standard”.