REACTOR PHYSICS EXPERIMENT IN A GRAPHITE-MODERATION SYSTEM FOR HTGR

The Japan Atomic Energy Agency (JAEA) started the Research and Development (R&D) to improve nuclear prediction techniques for High Temperature Gas-cooled Reactors (HTGRs). The objectives are to introduce a generalized bias factor method to avoid full mock-up experiment for the first commercial HTGR and to introduce reactor noise analysis to High Temperature Engineering Test Reactor (HTTR) experiment to observe sub-criticality. To achieve the objectives, the reactor core of graphite-moderation system named B7/4”G2/8”p8EUNU+3/8”p38EU(1) was newly composed in the B-rack of Kyoto University Critical Assembly (KUCA). The core is composed of the fuel assembly, driver fuel assembly, graphite reflector, and polyethylene reflector. The fuel assembly is composed of enriched uranium plate, natural uranium plate and graphite plates to realize the average fuel enrichment of HTTR and it’s spectrum. However, driver fuel assembly is necessary to achieve the criticality with the small-sized core. The core plays a role of the reference core of the bias factor method, and the reactor noise was measured to develop the noise analysis scheme. In this study, the overview of the criticality experiments is reported. The reactor configuration with graphite moderation system is rare case in the KUCA experiments, and this experiment is expected to contribute not only for an HTGR development but also for other types of a reactor in the graphite moderation system such as a molten salt reactor development.

Ventricular tachycardia in cardiac sarcoidosis -prognosis, characterization of ventricular substrates and outcomes of treatment-

Background

The prognosis, the underlying substrate and clinical outcomes of treatment are unclear in patients with cardiac sarcoidosis (CS)-related ventricular tachycardia (VT).

Objective

This study investigated the prognosis and the relationship between electroanatomical mapping (EAM) and imaging findings in patients with CS-related VT.

Methods

A total of 203 CS patients (Age 68.1±11.6 years, 87 males) were enrolled at two tertiary care medical centers between 2000 and 2018. All met the 2016 Japanese Circulation Society guidelines for diagnosis of CS. They were followed for a composite of major adverse cardiac events (MACE) including cardiac death, heart transplantation, unscheduled hospitalization for heart failure, and life-threatening ventricular arrhythmias. Distribution of late gadolinium enhancement (LGE) on cardiac MRI (CMR) and/or an abnormal myocardial 18F-fluorodeoxyglucose (FDG) uptake on positron emission tomography at diagnosis were examined. The relationship between EAM and the image findings were also analyzed in patients with radiofrequency ablation (RFA) for VT.

Results

During a median follow-up of 53 months, 87 of the 203 patients (43%) experienced a MACE. Baseline factors associated with MACE were presence of sustained VT (HR, 2.43, 95% CI 1.54–3.85, P<0.001), left ventricular ejection fraction below 50% (HR, 1.95 95% CI 1.07–3.56, P=0.029), and abnormal myocardial FDG uptake (HR, 2.42 95% CI 1.04–5.61, P=0.039). Overall, 69 of the 203 patients (34%) experienced sustained VT. Abnormal myocardial FDG uptake was significantly more prevalent in patients with VT than in those without (92.7% vs. 78.5%, P=0.02). A total of 25 patients (9.9%) required RFA for CS-related VT (Age 64.0±8.7 years, 12 males, 1.32±0.56 RFAs per patient). Abnormal electrocardiograms (EGM) were observed in 22 of the 25 patients (88%). LGE was more frequent than abnormal FDG uptake in areas with an abnormal EGM (77% vs. 41%; P=0.002). Over a mean follow-up period of 67-months, 13 of the 25 patients with RFA (52%) remained free of VT episodes (Figure). VT recurred in nine of the 12 patients with RFA and in 17 of the 47 patients without RFA, but was suppressed by intensive pharmacologic therapy such as the combined use of amiodarone and sotalol. In patients with CS-related VT, survival without experiencing a MACE did not differ in participants with or without RFA.

Conclusions

In our 203 CS patients, sustained VT and abnormal FDG uptake were associated with worse cardiac outcomes. The prevalence of abnormal FDG uptake was significantly higher in patients with CS-related VT, LGE on CMR was more frequent within localized areas of an abnormal EGM, suggesting that both scar itself and the associated inflammation were involved in the pathogenesis of CS-related VT. Successful RFA of CS-related VT is still challenging, and recurrence is common. Preprocedural CMR can be useful in detecting abnormal EGMs that are potential targets for substrate ablation.

Funding Acknowledgement

Type of funding source: None

Cardiac function at diagnosis is important prognostic factor in patients with cardiac sarcoidosis -from Japanese nationwide questionnaire survey-

Background

Sarcoidosis is a systemic non-caseating granulomatous disease of unknown etiology. Cardiac involvement (cardiac sarcoidosis, CS) has been reported to be an important prognostic factor in this disease because of heart failure and/or ventricular arrhythmia, and corticosteroid therapy is usually prescribed to prevent cardiac events. However, little is known about the relationship of cardiac function and concomitant corticosteroid therapy on later cardiac events in CS.

Objective

We evaluated the relationship between prognosis and left ventricular ejection fraction (LVEF) at the time of diagnosis in CS patients from the Japanese nationwide questionnaire survey.

Methods

Total of 757 Japanese patients from 57 hospitals who diagnosed CS were examined. Patients who unsatisfied the criteria of the Japanese new guidelines, or who underwent cardiac transplantations were excluded, and 420 patients (287 females, mean age 60±13 years old, median follow-up periods 1864 days [interquartile range: 845–3159 days]) were analyzed. The relationship of adverse events (all-cause death, cardiovascular death, and appropriate ICD [Implantable Cardioverter Defibrillator] discharge) and LVEF (with corticosteroid 84%) (low LVEF: LVEF≤35% n=98 [with corticosteroid in 78%], moderate LVEF: LVEF 35–50% n=104 [with corticosteroid in 93%], normal LVEF: 50≤LVEF n=218 [with corticosteroid in 83%]) were evaluated respectively.

Results

89 CS patients developed all-cause death (n=50), cardiovascular death (n=30) or appropriate ICD discharge (n=48). The frequency of corticosteroid therapy was not different in the each LVEF group, but Kaplan-Meier analysis revealed that all-cause death, cardiovascular death, and all cardiovascular adverse events were more observed in lower LVEF group (log-rank p<0.0001). Furthermore, multivariate Cox hazard analysis revealed that LVEF was a most important independent prognostic factor in CS.

Conclusion

This Japanese nationwide questionnaire survey data showed that initial LVEF was an independent and strong prognostic predictor in CS, therefore primary prevention would be needed even after starting corticosteroid in patients with decreased cardiac function.

Funding Acknowledgement

Type of funding source: None

Long time clinical course of cardiac sarcoidosis with corticosteroid therapy -from Japanese nationwide questionnaire survey-

Background

Sarcoidosis is a systemic inflammatory syndrome of unknown etiology and cardiac involvement has been reported to be an important prognostic factor in this disease. An autopsy study has reported that the frequency of this cardiac involvement (cardiac sarcoidosis: CS) varies in the different countries and races and very frequent in Japanese patients. We therefore performed the nationwide questionnaire survey and try to clarify the clinical characteristics and corticosteroid effect in CS, especially focused on arrhythmic events in this disease.

Methods

Total of 757 Japanese patients from 57 hospitals who diagnosed CS were examined. Patients who unsatisfied the criteria of the Japanese new guidelines, or who underwent cardiac transplantations were excluded, and 420 patients (287 females, median follow-up periods 1864 days [interquartile range: 845–3159 days]) were analyzed. The clinical outcome and corticosteroid effect were evaluated.

Results

Clinical characteristics at diagnosis was as follows: female dominant (68%), mean age of 60±13 years old, mean left ventricular ejection fraction was 49±16%. Arrhythmic events were very frequently observed as an initial cardiac manifestation in 263 patients (62%) of CS, of which atrioventricular block (AVB) in 174 (41%), ventricular tachycardia (VT) in 73 (17%) and AVB with VT in 17 (4%) (Figure 1A). Pacemaker was implanted in 166 patients (40%) and defibrillators was 137 patients (33%). Corticosteroid was prescribed in 144 (83%) of 174 patients with AVB and in 62 (85%) of 73 patients with VT. Initial dose was mean 47.9 mg and maintenance dose of mean 7.3 mg. Corticosteroid improved VT as good as AVB (27% vs. 29%). However, corticosteroid sometimes worsened VT events compared with AVB (10% vs. 2%) (Figure 1B). During the course of follow-up, 32 patients were needed to increase corticosteroid in 23 of AVB and 10 of VT cases. However, there were no difference in mortality between the groups, whether or not to increase corticosteroid. All survival rate was 92% (5-year mortality), 83% (10-year mortality) and free from all cause death and defibrillator charge was 81% (5 year), 71% (10 year).

Conclusion

Fatal arrhythmia is commonly observed in CS as a primary symptom. Corticosteroid sometimes worsen ventricular arrhythmia and appropriate defibrillator discharge was common. Thus, careful attention for activating ventricular arrhythmia would be needed during the follow-up period even after corticosteroid therapy.

Funding Acknowledgement

Type of funding source: None

Long-term follow up ventricular tachycardia patients with preserved cardiac function -from Japanese cardiac sarcoidosis nationwide questionnaire survey-

Background

Prior ventricular tachycardia (VT) and low left ventricular ejection fraction (LVEF) are the most important prognostic factors in cardiac sarcoidosis (CS). Recently diagnosis of CS was renewed according to Japanese new guidelines. Patients with preserved cardiac function often have VT events, thus new guidelines recommends to assess the implantable cardioverter defibrillator (ICD) implantation for CS patients with preserved LVEF (35%≤LVEF<50%). However, the long-term prognosis of CS patients with preserved LVEF is unclear.

Objective

In CS patients with preserved LVEF, we evaluated the prognosis between VT manifestation and non-VT manifestation groups at CS diagnosis from Japanese nationwide questionnaire survey.

Methods

Total of 757 Japanese patients from 57 hospitals who diagnosed CS were examined. Patients who unsatisfied the criteria of the Japanese new guidelines, who had LVEF≤35%, LVEF>50%, or who underwent cardiac transplantations were excluded. 104 patients with LVEF 35–50% (67 females, mean age 60±15 years old, median follow-up periods 2134 days [interquartile range: 758–2935 days]) were analyzed. The prognosis between VT manifestation and non-VT manifestation groups at CS diagnosis were evaluated.

Results

30 patients had VT manifestation at CS diagnosis and 24 patients (80%) received ICDs. 74 patients had no VT manifestation at CS diagnosis and 19 patients (44%) received ICDs during follow up period. All-cause mortality was not different between two groups (Figure). Appropriate ICD therapy of non-VT manifestation group was significantly lower compared with that of VT manifestation group (log-rank p=0.001), however considerable number (n=7, 15%) of non-VT manifestation group had appropriate ICD therapy event during follow-up period. Cox hazard analysis revealed that concomitant non-sustained VT (NSVT) with atrioventricular block (AVB) was a predictor of appropriate ICD therapy in non-VT manifestation group.

Conclusion

This nationwide survey showed that considerable number of CS patients with preserved LVEF had VT events, independent of VT manifestation. Concomitant NSVT with AVB was a predictor of VT events, and ICD implantation should be assessed.

Funding Acknowledgement

Type of funding source: None

Micro-embolic risks during radiofrequency and cryoballoon-ablation of atrial fibrillation -analysis from real-time carotid artery doppler monitoring-

Background

Catheter ablation of atrial fibrillation (AF) is associated with risks of silent cerebral events. However, the timing of intraprocedural micro-embolic events or differences between open-irrigated radiofrequency (RF) and cryoballoon (Cryo) ablation are unclear. Newly developed real-time carotid artery Doppler is a simple non-invasive method to detect micro-embolic signals (MESs) during ablation.

Objective

We investigated the timing of detecting MESs during RF and Cryo ablation of AF.

Methods

During the first pulmonary vein isolation (PVI) session of AF, MESs were monitored by real-time carotid artery Doppler monitoring throughout the procedure. The MES counts were collected and evaluated separately during the different steps of the procedure (Figure).

Results

Thirty-three AF patients (RF/Cryo: 22/11 cases, 9 females, 69.5±11.6 y.o) were included. PVI was successfully accomplished in all patients with no major complications. The MES count was significantly greater in the RF group than Cryo group (table). In both groups, left atrial (LA) access (interatrial puncture) and sheaths insertion to the LA generated a significant number of MESs (RF: 1690 of 9116 MESs [18.5% of the total MESs], Cryo: 793 of 2285 MESs [34.7%]). In the RF group, MESs were observed incessantly during PVI (Figure). The LA dwell time was significantly longer in the RF group than Cryo group (table). In the RF group, the MES count was significantly greater in the longer LA dwell time group (LA dwell time >130min) than the shorter group (464.2±179.7 vs 302.6±138.2: P=0.049). During the cryo-applications in the Cryo group, the MESs were greatest during the first cryoballoon application (625 of 2285 MESs [27.4%]).

Conclusions

There were more MESs during RF ablation than cryoablation. MESs were recorded during a variety of steps throughout the procedure. In the RF group, most of MESs were recorded incessantly during radiofrequency ablation and greater number of MESs were recorded in patients with longer LA dwell time. In the Cryo group, most of MESs occurred during phases with a high probability of gaseous emboli.

Funding Acknowledgement

Type of funding source: None

The safety of catheter ablation of atrial fibrillation in elderly patients -analysis of the nationwide database in Japan, JROAD-DPC-

Background

“Age” is one of the major concerns and determinants of the indications for catheter ablation (CA) of atrial fibrillation (AF). There are little safety data on CA of AF according to the age. This study aimed to assess the safety of CA in elderly patients undergoing CA of AF.

Methods and results

We investigated the complication rate of CA of AF for the different age groups (<60 years, 60–65, 65–70, 70–75, 75–80, 80–85, and ≥85) by a nationwide database (Japanese Registry Of All cardiac and vascular Diseases [JROAD]-DPC). The JROAD-DPC included 73,296 patients (65±11 years, 52,883 men) who underwent CA of AF from 516 hospitals in Japan. Aged patients had more comorbidities and a significantly increased CHADS2 score and higher rate of female according to a higher age. The overall complication rate was 2.6% and in-hospital mortality was 0.05%. By comparing each age group, complications occurred more frequently in higher aged groups. A multivariate adjusted hazard ratio revealed an increased age was independently and significantly associated with the overall complications (odds ratio was 1.25, 1.35, 1.72, 1.86, 2.76 and 3.13 respectively; reference <60 years).

Conclusions

The frequency of complications was significantly higher according to a higher age. We should take note of the indications and procedure for CA of AF in aged patients.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): Intramural Research Fund 17 (Kusano) for Cardiovascular Diseases of the National Cerebral and Cardiovascular Center

IAP inhibitor, Embelin increases VCAM-1 levels on the endothelium, producing lymphocytic infiltration and antitumor immunity

There is an increasing unmet need for successful immunotherapeutic interventions. Lymphocyte extravasation via tumor tissue endothelial cells (TECs) is required for lymphocyte infiltration into tumor sites. This study aimed to investigate the clinical significance of dysfunctional TECs in pancreatic ductal adenocarcinoma (PDAC) and identify chemical compounds that boost tumor-infiltrating lymphocyte (TIL) numbers. We performed immunohistochemical detection and clinicopathological analysis of VCAM-1 on TECs, which is essential for lymphocyte trafficking. We characterized the gene expression profiles of TECs from fresh PDAC tissues. We isolated compounds that upregulated VCAM-1 and E-selectin expression in TECs and examined their biological activities. Compared to endothelial cells from chronic pancreatitis tissue, TECs showed significantly lower VCAM-1 and E-selectin expression and significant weaknesses in lymphocyte adhesion and transmigration, resulting in decreased T cell infiltration around vessels. Patients with a relatively high percentage of VCAM-1⁺ vessels among all vessels in PDAC tissue had an improved prognosis. A bioinformatics survey demonstrated that TNFR1 signaling was involved in abnormal VCAM-1 and E-selectin expression in TECs. We screened compounds affecting TNFR1 signaling, and the IAP inhibitor, Embelin, induced these molecules on TECs and enhanced T cell adhesion to TECs and transmigration. Furthermore, in vivo, Embelin enhanced tumor-infiltrating T cell numbers, leading to an antitumor immune response. Embelin accelerates TIL infiltration and the antitumor immune response by recovering VCAM-1 expression in TECs. Our strategy may be a therapeutic approach for accelerating the immunotherapeutic response in immune-quiescent tumors, leading to clinical trials’ success.

Amplification of autocrine motility factor and its receptor in multiple myeloma and other musculoskeletal tumors

•

This study is a large scale cohort of the patients with malignant musculoskeletal tumors to determine the expression levels of Autocrine Motility factor (AMF) and its receptor (AMFR).

•

We Visualization of amplified Autocrine motility factor (AMF) and its receptor (AMFR) in musculoskeletal tumors.

•

A novel software aimed at analyzing numerous cell-to-cell and ligand-to-receptor interactions was developed, which lead to visualization of bone tumor microenvironment.

Autocrine motility factor (AMF: GPI) and its receptor AMFR (AMF Receptor: gp78) regulate the metastatic process. Here, we have tested the expression levels of AMF, AMFR, and AMF × AMFR in 1348 patients with musculoskeletal tumor. The results depicted here identified that multiple myeloma highly express AMF × AMFR value as compared with normal bone samples (p < 0.00001). To visualize the AMF × AMFR autocrine amplification in multiple myeloma microenvironment, we have developed a novel software aimed at analyzing numerous cell-to-cell and ligand-to-receptor interactions, i.e., Environmentome. It has led to the identification that myeloma-associated interactions with normal bone cells including osteoblast, osteoclast, immunological components, and others in a paracrine manner. In conclusion, the data showed that AMF × AMFR amplification is a clinical manifestation in bone microenvironment of multiple myeloma.

Motion tracking of 80-nm-size skyrmions upon directional current injections

Nanometer-scale skyrmions are prospective candidates for information bits in low-power consumption devices owing to their topological nature and controllability with low current density. Studies on skyrmion dynamics in different classes of materials have exploited the topological Hall effect and current-driven fast motion of skyrmionic bubbles. However, the small current track motion of a single skyrmion and few-skyrmion aggregates remains elusive. Here, we report the tracking of creation and extinction and motion of 80-nm-size skyrmions upon directional one-current pulse excitations at low current density of the order of 109 A m-2 in designed devices with the notched hole. The Hall motion of a single skyrmion and the torque motions of few-skyrmion aggregates have been directly revealed. The results exemplify low-current density controls of skyrmions, which will pave the way for the application of skyrmions.

AB1031 DYSKERATOTIC CELLS IN PERSISTENT PRURITIC SKIN LESIONS AS A PROGNOSTIC FACTOR IN ADULT-ONSET STILL’S DISEASE

Background:

Adult-onset Still’s disease (AOSD), a systemic inflammatory disorder, is characterized by high fever, evanescent rash, arthritis, and hyperferritinaemia. AOSD is also reported to be associated with other skin lesions, including persistent pruritic papules and plaques.

Objectives:

This study aimed to assess the significance of dyskeratotic skin lesions in Japanese AOSD patients.

Methods:

We retrospectively assessed the histology of persistent pruritic skin lesions and evanescent rashes and the relationship between dyskeratotic cells, serum markers, and outcomes in 20 Japanese AOSD patients, comparing AOSD histology with that of dermatomyositis (DM), drug eruptions, and graft-versus-host disease (GVHD).

Results:

Persistent pruritic lesions were characterized by scattered single keratinocytes with an apoptotic appearance confined to the upper layer of the epidermis and horny layer without inflammatory infiltrate. In contrast to AOSD, the histology of DM, drug eruption, and GVHD demonstrated dyskeratotic cells in all layers of the epidermis with inflammatory infiltrate. AOSD with evanescent rash showed no dyskeratotic cells. The dyskeratotic cells in pruritic AOSD lesions stained positive for ssDNA and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling, indicating apoptosis. Serum IL-18 was significantly higher in AOSD patients with dyskeratotic cells than those without, and generally required higher doses of glucocorticoids, immunosuppressants, and biologic agents. Two of ten AOSD patients with dyskeratotic cells died from haemophagocytic lymphohistiocytosis.

Conclusion:

Persistent pruritic AOSD skin lesions are characterized by dyskeratotic cells with apoptotic features, involving the upper layers of the epidermis. There may be a link to elevated IL-18. This dyskeratosis may be a negative prognostic indicator.

Disclosure of Interests:

None declared

Flightless anchors IQGAP1 and R-ras to mediate cell extension formation and matrix remodeling

Tractional remodeling of collagen fibrils by fibroblasts requires long cell extensions that mediate fibril alignment. The formation of these cell extensions involves flightless I (FliI), an actin-binding protein that contains a leucine-rich-repeat (LRR), which binds R-ras and may regulate cdc42. We considered that FliI interacts with small GTPases and their regulators to mediate assembly of cell extensions. Mass spectrometry analyses of FliI immunoprecipitates showed abundant Ras GTPase-activating-like protein (IQGAP1), which in immunostained samples colocalized with FliI at cell adhesions. Knockdown of IQGAP1 reduced the numbers of cell extensions and the alignment of collagen fibrils. In experiments using dominant negative mutants, cdc42 activity was required for the formation of short extensions while R-ras was required for the formation of long extensions. Immunoprecipitation of wild-type and mutant constructs showed that IQGAP1 associated with cdc42 and R-ras; this association required the GAP-related domain (1004–1237 aa) of IQGAP1. In cells transfected with FliI mutants, the LRR of FliI, but not its gelsolin-like domains, mediated association with cdc42, R-ras, and IQGAP1. We conclude that FliI interacts with IQGAP1 and co-ordinates with cdc42 and R-ras to control the formation of cell extensions that enable collagen tractional remodeling.

Multielectron-Ion Coincidence Spectroscopy of Xe in Extreme Ultraviolet Laser Fields: Nonlinear Multiple Ionization via Double Core-Hole States

Ultrafast multiphoton ionization of Xe in strong extreme ultraviolet free-electron laser (FEL) fields (91 eV, 30 fs, 1.6×10^{12}  W/cm^{2}) has been investigated by multielectron-ion coincidence spectroscopy. The electron spectra recorded in coincidence with Xe^{4+} show characteristic features associated with two-photon absorption to the 4d^{-2} double core-hole (DCH) states and subsequent Auger decay. It is found that the pathway via the DCH states, which has eluded clear identification in previous studies, makes a large contribution to the multiple ionization, despite the long FEL pulse duration compared with the lifetime of the 4d core-hole states.

Bone strength of the proximal femur in healthy subjects with ossification of the posterior longitudinal ligament

We compared the bone strength measured via quantitative computed tomography-based finite element method (QCT/FEM) between healthy adults with and without ossification of the posterior longitudinal ligament (OPLL). No statistically significant difference was observed in the bone strength between healthy adults with and without OPLL. Hyperostosis of the posterior longitudinal ligament in OPLL may not be associated with the systemic bone strength.

INTRODUCTION

Although patients with OPLL have been reportedly associated with increased level of bone mineral density (BMD) using dual-energy X-ray absorptiometry (DXA), little is known about the bone strength in OPLL subjects. The aim of this study is to investigate the bone strength measured via QCT/FEM in healthy subjects with OPLL using the medical check-up data, including whole-body CT scans.

METHODS

We examined 796 participants (529 men and 267 women) who underwent CT scans in a single health center between January 2008 and May 2009. We identified OPLL in whole spine and divided the subjects into two groups: non-OPLL and OPLL groups. We calculated the predicted bone strength (PBS) of the proximal femur using QCT/FEM and examined the bone mineral status of the calcaneus using quantitative ultrasound (QUS). We compared the PBS and the QUS parameters between the non-OPLL and OPLL groups.

RESULTS

Seventy-four subjects (9.3%; 57 men and 17 women) were diagnosed with OPLL in the whole spine. The OPLL group was significantly older than the non-OPLL group. No statistically significant difference was observed in the PBS and the QUS parameters between the non-OPLL and OPLL groups in both sexes. Furthermore, no statistically significant difference was noted in the PBS and the QUS parameters between two groups in age- and gender-matched analysis.

CONCLUSIONS

Our results suggest that hyperostosis of the posterior longitudinal ligament in OPLL may not be associated with bone strength and bone mineral status at the extremities.

Analysis of volume-phase-grating characteristics that a variety of refractive index distributions influence. Part 2: Analysis of spectral bandwidths and angular bandwidths, and the derivation of these equations

To expand the spectral bandwidths with high diffraction efficiency of volume phase (VP) gratings, it is important to know the influence of a variety of refractive index distributions (RIDs) inside the recording material on the bandwidths. The influence of various graded types of RIDs on the full width at half the maximum of the spectral bandwidth (${\lambda _{\rm FWHM}}$λ_FWHM) and the angular bandwidth (${\theta _{\rm FWHM}}$θ_FWHM) is investigated in the Bragg regime. It becomes clear that various graded types of RIDs influence their bandwidths and the characteristics, and the combination of the RIDs and refractive index modulation (${{ n}_m}$n_m) is the most important factor for obtaining the large bandwidths of VP gratings. Theoretically, the ${\lambda _{\rm FWHM}}$λ_FWHM are obtained as the values of 149.7 nm and 257.6 nm (${{ n}_m} = {0.045}$n_m=0.045) for the wavelengths of 900 nm and 1550 nm, respectively. Furthermore, I have succeeded in developing the expression for ${\lambda _{\rm FWHM}}$λ_FWHM and ${\theta _{\rm FWHM}}$θ_FWHM, using the proportional characteristics of VP gratings investigated in this work. The correlative coupling-length coefficients "G-factors" devised as a variety of RID functions in the previous paper are introduced into them. It is apparent that the derived equations of the bandwidths can be adapted to any graded type of RID that changes continuously from a triangular type to a rectangular type of VP grating, which has not been reported yet. The equations have made it easy to design ${\lambda _{\rm FWHM}}$λ_FWHM and ${\theta _{\rm FWHM}}$θ_FWHM of VP gratings.

Analysis of volume-phase-grating characteristics that a variety of refractive index distributions influence. Part 1: derivation of coupling coefficients and grating thickness, and characteristics of the G-factors

The equations for the coupling coefficient and the grating thickness of volume phase gratings are derived from Maxwell's equations in this work. The equations cover all graded types of refractive index distributions (RIDs) which change continuously from a triangular type to a rectangular type. The functions expressed as various graded types of RIDs, which are proposed in this work, are used among them. Furthermore, the new idea, which is the correlative coupling-length coefficient, is devised for the first time as a variety of RID function, "G-factor." The results based on the coupled mode theory in this work show a very close agreement under 0.2% with the results of the rigorous coupled-wave analysis method. The values of the grating thickness and the G-factor are confirmed with validity. By means of this new method, not only can the grating thickness of any graded type of VP grating which is under the Bragg condition be obtained very easily, but the spectral bandwidths and the angular bandwidths which are not under the Bragg condition can be controlled very easily and the configurations of RIDs can be estimated as well.

P5655Efficacy of new-generation atrial antitachycardia pacing for atrial tachyarrhythmias in patients with left ventricular dysfunction

Background

The progression to persistent atrial fibrillation (AF) is associated with a worse clinical outcome in patients with previous atrial tachyarrhythmias. New-generation atrial antitachycardia pacing (ATP) (Reactive ATP) reduced the progression to persistent AF in patients with pacemaker and preserved left ventricular (LV) function. However, little is known about the efficacy of Reactive ATP in patients with cardiac implantable electronic devices (CIED) and LV dysfunction.

Purpose

We aimed to investigate the efficacy of Reactive ATP for atrial tachyarrhythmias in patients with LV dysfunction (LV ejection fraction [LVEF] <40%).

Methods

This study included 423 patients with CIED and previous atrial tachyarrthythmias. Reactive ATP was programmed in 284 patients (ATP group) and 139 were implanted with a dual-chamber device without ATP function (control group). The differences in the success rate of ATP and incidence of progression to persistent AF (≥7 days) between the ATP and control groups were evaluated in 108 patients with LVEF <40% (reduced LVEF) and 315 with LVEF ≥40% (preserved LVEF). Patients with persistent AF were excluded from this study.

Results

During 710±337 days of follow-up period, 16 patients (15%) with reduced LVEF and 51 (16%) with preserved LVEF progressed to persistent AF (p=0.88). The mean ATP success rate was lower in patients with reduced LVEF than in those with preserved LVEF, although not statistically significant (reduced LVEF: 27.2±19.4% and preserved LVEF: 35.1±29.2%, p=0.12). The incidence of progression to persistent AF was significantly lower in the ATP group than in the control group both in patients with reduced and preserved LVEF (log-rank, reduced LVEF: p=0.0070 and preserved LVEF: p<0.0001) (Figure). Multivariate analysis showed that use of Reactive ATP and smaller left atrium were associated with lower incidences of persistent AF, while LVEF was not predictive of progression to persistent AF (Reactive ATP: hazard ratio [HR] 0.28, 95% confidence interval [CI] 0.17–0.46, p<0.0001, left atrium diameter: HR 1.03, 95% CI 1.00–1.07, p=0.030).

Figure 1

Conclusions

Reactive ATP was effective in preventing AF progression in patients with LV dysfunction.