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植田 典浩ウエダ ノリヒロ

所属部署医学研究科医学・医療教育学分野
職名講師
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Last Updated :2020/07/04

研究者基本情報

所属学協会

  • 日本不整脈心電学会
  • 日本循環器学会
  • 日本内科学会
  • 日本医学教育学会

研究活動情報

研究分野

  • ライフサイエンス, 自然人類学

論文

  • Optimal length of R-R interval segment window for Lorenz plot detection of paroxysmal atrial fibrillation by machine learning., Masaya Kisohara, Yuto Masuda, Emi Yuda, Norihiro Ueda, Junichiro Hayano, Biomedical engineering online, 19, (1) 49 - 49,   2020年06月16日, 査読有り, BACKGROUND: Heartbeat interval Lorenz plot (LP) imaging is a promising method for detecting atrial fibrillation (AF) in long-term monitoring, but the optimal segment window length for the LP images is unknown. We examined the performance of AF detection by LP images with different segment window lengths by machine learning with convolutional neural network (CNN). LP images with a 32 × 32-pixel resolution of non-overlapping segments with lengths between 10 and 500 beats were created from R-R intervals of 24-h ECG in 52 patients with chronic AF and 58 non-AF controls as training data and in 53 patients with paroxysmal AF and 52 non-AF controls as test data. For each segment window length, discriminant models were made by fivefold cross-validation subsets of the training data and its classification performance was examined with the test data. RESULTS: In machine learning with the training data, the averages of cross-validation scores were 0.995 and 0.999 for 10 and 20-beat LP images, respectively, and > 0.999 for 50 to 500-beat images. The classification of test data showed good performance for all segment window lengths with an accuracy from 0.970 to 0.988. Positive likelihood ratio for detecting AF segments, however, showed a convex parabolic curve linear relationship to log segment window length and peaked at 85 beats, while negative likelihood ratio showed monotonous increase with increasing segment window length. CONCLUSIONS: This study suggests that the optimal segment window length that maximizes the positive likelihood ratio for detecting paroxysmal AF with 32 × 32-pixel LP image is 85 beats.
  • Non-REM Sleep Marker for Wearable Monitoring: Power Concentration of Respiratory Heart Rate Fluctuation, Junichiro Hayano, Norihiro Ueda, Masaya Kisohara, Yutaka Yoshida, Haruhito Tanaka, Emi Yuda, Applied Sciences, 10, (9) 3336 - 3336,   2020年05月11日, 査読有り, A variety of heart rate variability (HRV) indices have been reported to estimate sleep stages, but the associations are modest and lacking solid physiological basis. Non-REM (NREM) sleep is associated with increased regularity of respiratory frequency, which results in the concentration of high frequency (HF) HRV power into a narrow frequency range. Using this physiological feature, we developed a new HRV sleep index named Hsi to quantify the degree of HF power concentration. We analyzed 11,636 consecutive 5-min segments of electrocardiographic (ECG) signal of polysomnographic data in 141 subjects and calculated Hsi and conventional HRV indices for each segment. Hsi was greater during NREM (mean [SD], 75.1 [8.3]%) than wake (61.0 [10.3]%) and REM (62.0 [8.4]%) stages. Receiver-operating characteristic curve analysis revealed that Hsi discriminated NREM from wake and REM segments with an area under the curve of 0.86, which was greater than those of heart rate (0.642), peak HF power (0.75), low-to-high frequency ratio (0.77), and scaling exponent α (0.77). With a cutoff >70%, Hsi detected NREM segments with 77% sensitivity, 80% specificity, and a Cohen’s kappa coefficient of 0.57. Hsi may provide an accurate NREM sleep maker for ECG and pulse wave signals obtained from wearable sensors.
  • Impact of Heart Rate Fragmentation on the Assessment of Heart Rate Variability, Junichiro Hayano, Masaya Kisohara, Norihiro Ueda, Emi Yuda, Applied Sciences, 10, (9) 3314 - 3314,   2020年05月10日, 査読有り, Heart rate fragmentation (HRF) is a type of sinoatrial instability characterized by frequent (often every beat) appearance of inflection in the R-R interval time series, despite the electrocardiograms appearing to be sinus rhythm. Because the assessment of parasympathetic function by heart rate variability (HRV) analysis depends on the assumption that the high-frequency component (HF, 0.15–0.4 Hz) of HRV is mediated solely by the cardiac parasympathetic nerve, HRF that is measured as a part of HF power confounds the parasympathetic functional assessment by HRV. In this study, we analyzed HRF in a 24-h electrocardiogram big data and investigated the changes in HRF with age and sex and its influence on the assessment of HRV. We observed that HRF is often observed during childhoods (0–20 year) and increased after 75 year, but it has a large impact on individual differences in HF power at ages 60–90.
  • Difference in autonomic nervous effect of blue light depending on the angle of incidence on the eye., Emi Yuda, Yutaka Yoshida, Norihiro Ueda, Junichiro Hayano, BMC research notes, 13, (1) 141 - 141,   2020年03月10日, 査読有り, OBJECTIVE: Blue light has been attributed to the adverse biological effects caused by the use of smartphones and tablet devices at night. However, it is not realistic to immediately avoid nighttime exposure to blue light in the lifestyle of modern society, so other effective methods should be investigated. Earlier studies reported that inferior retinal light exposure causes greater melatonin suppression than superior retinal exposure. We examined whether the autonomic responses to blue light depends on the angle of incidence to the eye. RESULTS: In eight healthy subjects, blue light from organic electroluminescent lighting device (15.4 lx at subjects' eye) was exposed from 6 angles (0º, 30º, 45º, 135º, 150º, and 180º) for 5 min each with a 10-min interval of darkness. After adjusting the order effect of angles, however, no significant difference in heart rate or autonomic indices of heart rate variability with the angle of incidence was detected in this study.
  • Association between PM2.5 exposure and heart rate variability for the patients with cardiac problems in Japan, Kanawat Paoin, Kayo Ueda, Xerxes Tesoro Seposo, Junichiro Hayano, Ken Kiyono, Norihiro Ueda, Takashi Kawamura, Akiko Honda, Hirohisa Takano, AIR QUALITY ATMOSPHERE AND HEALTH, 13, (3) 339 - 347,   2020年03月, 査読有り, A reduction in heart rate variability (HRV) is reportedly associated with an increased risk of cardiovascular mortality and morbidity. In previous studies, an inverse association was noted between HRV and particulate air pollution, but the sample populations were small and most consisted only of elderly individuals. We examined the association between 24-h HRV and fine particulate matter (PM2.5) in a large study population spanning 7 prefectures in Japan from April 2010 through March 2013. Meta-analysis was also performed. In total, 59,493 records of 24-h HRV for patients aged 20-90 years with symptoms/signs suggestive of heart disease were included in this analysis. Air pollution data were obtained from the National Institute for Environmental Studies. Regression models were used to examine the association between daily concentration of PM2.5 and HRV indices (e.g., standard deviation of normal-to-normal (SDNN), SD of average NN internals calculated over short periods (SDANN), very low frequency (VLF), and ultra-low frequency (ULF)). The model was adjusted for age, sex, temperature, and relative humidity. We examined the lagged association for single (up to lag3) and moving average (up to lag03). We found that decreases in HRV indices, especially for SDNN, SDANN, VLF, and ULF, were associated with PM2.5 in Hokkaido, Chiba, Tokyo, and Kanagawa. In contrast, there was no clear association between HRV with PM2.5 in Saitama and Aichi. Meta-analysis revealed significant decreases in SDNN, SDANN, VLF, and ULF were associated with PM2.5. Short-term exposure to PM2.5 was associated with lower 24-h HRV in patients with symptoms/signs suggestive of heart disease.
  • Effects of aging on foot pedal responses to visual stimuli., Emi Yuda, Yutaka Yoshida, Norihiro Ueda, Itaru Kaneko, Yutaka Miura, Junichiro Hayano, Journal of physiological anthropology, 39, (1) 3 - 3,   2020年02月14日, 査読有り, BACKGROUND: Car accidents due to unexpected forward or backward runaway by older drivers are a serious social problem. Although the cause of these accidents is often attributed to stepping on the accelerator instead of the brake, it is difficult to induce such pedal application errors systematically with usual drive simulators. We developed a simple personal computer system that induces the pedal errors, and investigate the effects of age on the error behaviors. METHODS: The system consisted of a laptop computer and a three-pedal foot mouse. It measured response time, accuracy, and flexibility of pedal operation to visual stimuli. The system displayed two open circles on the computer display, lighting one of the circles in a random order and interval. Subjects were instructed to press the foot pedal with their right foot as quickly as possible when the circle was lit; the ipsilateral pedal to the lit circle in a parallel mode and the contralateral pedal in a cross mode. When the correct pedal was pressed, the light went off immediately, but when the wrong pedal was pressed, the buzzer sounded and the light remained on until the correct pedal was pressed. During a 6-min trial, the mode was switched between parallel and cross every 2 min. During the cross mode, a cross mark appears on the display. The pedal responses were evaluated in 52 subjects divided into young (20-29 years), middle-aged (30-64 years), and older (65-84 years) groups. Additionally, the repeatability of the pedal response characteristic indicators was examined in 14 subjects who performed this test twice. RESULTS: The mean response time was 95 ms (17%) longer in the older group than in the young group. More characteristically, however, the older group showed 2.1 times more frequent pedal errors, fell into long hesitations (response freezing > 3 s) 16 times more often, and took 1.8 times longer period to correct the wrong pedal than the young groups. The indicators of pedal response characteristics showed within-individual repeatability to the extent that can identify the age-dependent changes. CONCLUSIONS: Hesitations and extended error correction time can be associated with increased crash risk due to unexpected runaway by older drivers. The system we have developed may help to uncover and evaluate physiological characteristics related to crash risk in the elderly population.
  • Inter-arm difference of systolic blood pressure measured by automated double-cuff device is associated with arterial stiffness in patients with hypertension., Masato Iida, Yuko Ishiguro, Norihiro Ueda, Haruo Honjo, Blood pressure monitoring, 25, (1) 26 - 33,   2020年02月, 査読有り, PURPOSE: Inter-arm differences of SBP ≧5 mmHg have been associated with all-cause and cardiovascular mortalities in hypertensive subjects. Inter-arm differences of SBP appears to be mediated by arterial stiffness. We hypothesized inter-arm differences of SBP ≧5 mmHg may be related to higher pulse pressure/stroke volume index, a surrogate marker of arterial stiffness. MATERIALS AND METHODS: To obtain inter-arm differences of SBP (the absolute difference of right and left arm) and ankle-brachial index, bilateral blood pressures were measured simultaneously at the four limbs using an automated oscillometric device in patients with treated hypertension (n = 234) and in normotensive subjects (n = 40). Pulse pressure was calculated as SBP-DBP. Stroke volume was obtained by time-velocity integral method using echocardiography. Left ventricular mass and relative wall thickness were calculated by the conventional methods. RESULTS: All hypertensive patients were medically treated and had average blood pressure levels of 135/85 mmHg. Inter-arm differences of SBP ≧5 mmHg was detected in 26.5% of hypertensive patients. Hypertensive patients with inter-arm differences of SBP ≧5 mmHg had higher pulse pressure/stroke volume index, lower ankle-brachial index, higher BMI, and higher relative wall thickness, higher prevalence of female than those with inter-arm differences of SBP <5 mmHg. Multiple linear regression analysis confirmed inter-arm differences of SBP ≧5 mmHg was associated with higher pulse pressure/stroke volume index, higher relative wall thickness, and lower ankle-brachial index. CONCLUSION: Inter-arm difference of SBP measured by automated double-cuff device was related to large artery stiffness in patients with hypertension.
  • Association of left atrial phasic volumes with systemic arterial stiffness and ankle-brachial index in hypertensive patients, M. Iida, M. Yamamoto, Y. Ishiguro, M. Yamazaki, N. Ueda, H. Honjo, K. Kamiya, Journal of Human Hypertension, 31, (4) 270 - 277,   2017年04月, 査読有り, © 2017 Macmillan Publishers Limited, part of Springer Nature. Left atrial (LA) phasic volumes consist of reservoir, conduit and booster pump volumes. Arterial stiffness is linked to lower systemic arterial compliance (SAC) contributing to cardiac afterload. Arterial stiffness may be a modulator of LA phasic volumes. Echocardiography was performed in 161 hypertensive patients and in 50 normotensive subjects in order to assess biplane LA volumes (maximum, before atrial contraction, minimum), early and late diastolic mitral annular velocity (e′ and a′), and LV stroke volume. LA emptying volumes (total, passive, active) were calculated from these LA volumes. Blood pressures were measured using an automated oscillometric device simultaneously at the four limbs for evaluating pulse pressure (PP) and ankle-brachial index (ABI). SAC was estimated by the ratio of LV stroke volume indexed by body surface area (BSA) divided by PP. All three LA volumes, LA total volume and LA active emptying volume were greater in hypertensive patients than in normotensive subjects. A multiple linear regression analysis indicated that LA passive emptying volume (reservoir=early diastole)/BSA correlated positively with ABI after being adjusted for age, gender, BSA, LV mass, max LA volume, e′ and SAC in hypertensive patients. LA active emptying volume (booster=late diastole)/BSA correlated positively with SAC after being adjusted for age, gender, BSA, LV mass, LA volume before atrial contraction, a′ and ABI. LA reservoir volume was associated with ABI, and LA booster volume was related to systemic arterial stiffness in hypertensive patients, suggesting the LA-arterial coupling in this clinical setting.
  • The role of gap junctions in stretch-induced atrial fibrillation, Norihiro Ueda, Mitsuru Yamamoto, Haruo Honjo, Itsuo Kodama, Kaichiro Kamiya, Cardiovascular Research, 104, (2) 364 - 370,   2014年11月01日, 査読有り, © 2014 The Author. Aims The aim of this study was to investigate the role of gap junctions in atrial fibrillation (AF) by analysing the effects of a gap junction enhancer and blocker on AF vulnerability and electrophysiological properties of isolated hearts. Methods and results The acute atrial stretch model of AF in the isolated rabbit heart was used. Sustained AF (SAF) was induced by a burst of high-frequency stimulation of the Bachmann's bundle. The effective refractory period (ERP) was measured, and the total conduction time (TCT) and the pattern of conduction of the anterior surface of the left atrium were monitored by using an optical mapping system. The effect of enhancing gap junction function by 100-1000 nM rotigaptide (ZP123) and block by 30 μM carbenoxolone on these parameters was measured. SAF inducibility was increased with an elevation of intra-atrial pressure. Enhanced gap junction conductance induced by treatment with 100-1000 nM rotigaptide reduced SAF inducibility, and the gap junction blocker carbenoxolone increased SAF inducibility. In the absence of gap junction enhancer or blocker, normal conduction was observed at 0 cmH2O. When intra-atrial pressure was raised to 12 cmH2O, the conduction pattern was changed to a heterogeneous zig-zag pattern and TCT was prolonged. Conduction pattern was not affected by either agent. Rotigaptide shortened TCT, whereas carbenoxolone prolonged TCT. ERP was significantly shortened with an increase in intra-atrial pressure, but ERP was unaffected by either agent. Conclusion Gap junction modulators changed AF inducibility through their effects on atrial conduction, not by altering ERP.
  • Urinary type IV collagen is related to left ventricular diastolic function and brain natriuretic peptide in hypertensive patients with prediabetes, Masato Iida, Mitsuru Yamamoto, Yuko S. Ishiguro, Masatoshi Yamazaki, Norihiro Ueda, Haruo Honjo, Kaichirou Kamiya, Journal of Diabetes and its Complications, 28, (6) 824 - 830,   2014年11月01日, 査読有り, © 2014 Elsevier Inc. All rights reserved. Aim: Urinary type IV collagen is an early biomarker of diabetic nephropathy. Concomitant prediabetes (the early stage of diabetes) was associated with left ventricular (LV) diastolic dysfunction and increased brain natriuretic peptide (BNP) in hypertensive patients. We hypothesized that urinary type IV collagen may be related to these cardiac dysfunctions.Methods: We studied hypertensive patients with early prediabetes (HbA1c < 5.7% and fasting glucose > 110, n = 18), those with prediabetes (HbA1c 5.7-6.4, n = 98), and those with diabetes (HbA1c > 6.5 or on diabetes medications, n = 92). The participants underwent echocardiography to assess left atrial volume/body surface area (BSA) and the ratio of early mitral flow velocity to mitral annular velocity (E/e'). Left ventricular diastolic dysfunction (LVDD) was defined if patients had E/e' ≥ 15, or E/e' = 9-14 accompanied by left atrial volume/BSA ≥ 32 ml/mm2. Urinary samples were collected for type IV collagen and albumin, and blood samples were taken for BNP and HbA1c.Results: Urinary type IV collagen and albumin increased in parallel with the deterioration of glycemic status. In hypertensive patients with prediabetes, subjects with LVDD had higher levels of BNP and urinary type IV collagen than those without LVDD. In contrast, in hypertensive patients with diabetes, subjects with LVDD had higher urinary albumin and BNP than those without LVDD. Urinary type IV collagen correlated positively with BNP in hypertensive patients with prediabetes, whereas it correlated with HbA1c in those with diabetes.Conclusions: In hypertensive patients with prediabetes, urinary type IV collagen was associated with LV diastolic dysfunction and BNP.
  • Utility of cystatin C as a marker for the severity of aortic regurgitation in hypertensive patients, Masato Iida, Mitsuru Yamamoto, Yuko S. Ishiguro, Masatoshi Yamazaki, Norihiro Ueda, Haruo Honjo, Kaichirou Kamiya, Clinica Chimica Acta, 425, 259 - 264,   2013年10月21日, 査読有り, Background: Cystatin C, a cathepsin inhibitor, is involved in the remodeling of human aortic valve and left ventricle (LV). Objective: Cystatin C may be related to the severity of aortic regurgitation (AR). Methods: We measured cystatin C and CRP in hypertensive patients with mild-to-moderate AR (n = 120) and in those without AR (n = 128). Echocardiography was performed to assess the vena contracta width (the narrowest region of regurgitant jet, VCW) as a marker of the severity of AR, relative wall thickness as a marker of LV concentric remodeling, and the ratio of early peak mitral flow to early diastolic mitral annular velocity (E/e') as an index of LV diastolic function. Glomerular filtration rate (GFR) was estimated using the MDRD methods. Results: Cystatin C levels were greater in hypertensive patients with AR than in those without AR. A multiple linear regression analysis indicated cystatin C levels correlated with the VCW independent of GFR, body mass index, CRP, relative wall thickness, and E/e' in hypertensive patients with AR. Conclusions: Cystatin C was associated with the severity of regurgitation independent of renal function body composition chronic inflammation LV remodeling and diastolic function in hypertensive patients with mild-to-moderate AR. © 2013 Elsevier B.V.
  • Atrial selectivity in Na channel blockade by acute amiodarone, Tomoyuki Suzuki, Mikio Morishima, Sara Kato, Norihiro Ueda, Haruo Honjo, Kaichiro Kamiya, Cardiovascular Research, 98, (1) 136 - 144,   2013年04月, 査読有り, Aims Na channel blockers are often used to treat atrial fibrillation (AF), but may sometimes cause ventricular contractile dysfunction. However, amiodarone, a multi-channel blocker with Na channel block, causes less contractile dysfunction. In this study, we tested the hypothesis that Na channel block by amiodarone is selective in atrial myocytes (AM) compared with ventricular myocytes (VM).Methods and resultsNa currents (INa) were measured using whole-cell patch-clamp technique in isolated rabbit AM and VM. Amiodarone inhibited INa in AM (IC50: 1.8 ± 1.1 μM; n 8) much more than in VM (40.4 ± 11.9 μM; n 7, P < 0.01). Amiodarone at 10 μM shifted the steady-state inactivation relationship in AM (-16.2 ± 1.7 mV shift, n 12) compared with VM (-5.9 ± 0.7 mV shift; n 13; P < 0.01). For mexiletine, the inhibition of INa and inactivation curve shifts were comparable for AM and VM. The effects of amiodarone and mexiletine on conduction velocity (CV) in Langendorff-perfused rabbit hearts were evaluated using an optical mapping system. The decrease of CV by 3 μM amiodarone was significantly larger in the atrium (-18.9 ± 3.8 change; n 5) compared with the ventricle (-3.7 ± 3.7; n 5; P < 0.01). In contrast, mexiletine reduced CV equally in the atrium and the ventricle.ConclusionAmiodarone preferentially inhibits INa of AM compared with VM. Atrial selective Na channel block by amiodarone may contribute to treating AF with less effect on ventricular contractility than other Na channel blockers. © The Author 2012.
  • Detection of QT prolongation through approximation of the T wave on Gaussian mixture modeling., Shin Hibino, Norihiro Ueda, Mitsuru Horiba, Kenji Yasui, Yuusuke Kagamihara, Shuji Funahashi, Kaichiro Kamiya, Hiroyuki Honda, Circulation journal : official journal of the Japanese Circulation Society, 77, (11) 2728 - 35,   2013年, 査読有り, BACKGROUND: To establish a simple and accurate method for the automated identification of the end of a T wave, we approximated electrocardiograph (ECG) traces using a Gaussian mixture model in conjunction with a split-and-merge expectation-maximization algorithm. METHODS AND RESULTS: A total of 286 ECG traces of heart beats of 50 healthy men were used as control data and ECGs from 15 subjects recorded before and after 400mg oral moxifloxacin as positive controls. An experienced cardiologist determined the reference points by visual inspection of the original ECGs. The primary estimated point for the end of the T wave was selected as the point 2 ms before the point at which the gradient of the approximated wave was not steeper than the common threshold value. This point was then adjusted by applying modification rules proposed by an experienced cardiologist. The absolute value of the average interval between the resulting final estimated point and the manually selected reference point was 1.8±7.7 ms for the control data. After treatment with moxifloxacin, the average QT interval, corrected by Bazett's formula, showed a 17.2±27.1 ms prolongation with a lower bound of the 95% confidence interval of 4.9 ms. CONCLUSIONS: When the modification rules were applied, the accuracy of QT measurement was improved, and the present system was capable of detecting QT prolongation correctly.
  • Inhibition of intercellular coupling stabilizes spiral-wave reentry, whereas enhancement of the coupling destabilizes the reentry in favor of early termination, Yoshio Takemoto, Hiroki Takanari, Haruo Honjo, Norihiro Ueda, Masahide Harada, Sara Kato, Masatoshi Yamazaki, Ichiro Sakuma, Tobias Opthof, Itsuo Kodama, Kaichiro Kamiya, AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY, 303, (5) H578 - H586,   2012年09月, 査読有り, Takemoto Y, Takanari H, Honjo H, Ueda N, Harada M, Kato S, Yamazaki M, Sakuma I, Opthof T, Kodama I, Kamiya K. Inhibition of intercellular coupling stabilizes spiral-wave reentry, whereas enhancement of the coupling destabilizes the reentry in favor of early termination. Am J Physiol Heart Circ Physiol 303: H578-H586, 2012. First published June 15, 2012; doi:10.1152/ajpheart.00355.2012.-Spiral-wave (SW) reentry is a major organizing principle of ventricular tachycardia/fibrillation (VT/VF). We tested a hypothesis that pharmacological modification of gap junction (GJ) conductance affects the stability of SW reentry in a two-dimensional (2D) epicardial ventricular muscle layer prepared by endocardial cryoablation of Langendorff-perfused rabbit hearts. Action potential signals were recorded and analyzed by high-resolution optical mapping. Carbenoxolone (CBX; 30 mu M) and rotigaptide (RG, 0.1 mu M) were used to inhibit and enhance GJ coupling, respectively. CBX decreased the space constant (lambda) by 36%, whereas RG increased it by 22-24% (n = 5; P < 0.01). During centrifugal propagation, there was a linear relationship between the wavefront curvature (kappa) and local conduction velocity (LCV): LCV = LCV0 - D . kappa (D, diffusion coefficient; LCV0, LCV at kappa = 0). CBX decreased LCV0 and D by 27 +/- 3 and 57 +/- 3%, respectively (n = 5; P < 0.01). RG increased LCV0 and D by 18 +/- 3 and 54 +/- 5%, respectively (n = 5, P < 0.01). The regression lines with and without RG crossed, resulting in a paradoxical decrease of LCV with RG at kappa > similar to 60 cm(-1). SW reentry induced after CBX was stable, and the incidence of sustained VTs (>30 s) increased from 38 +/- 4 to 85 +/- 4% after CBX (n = 18; P < 0.01). SW reentry induced after RG was characterized by decremental conduction near the rotation center, prominent drift and self-termination by collision with the anatomical boundaries, and the incidence of sustained VTs decreased from 40 +/- 5 to 17 +/- 6% after RG (n = 13; P < 0.05). These results suggest that decreased intercellular coupling stabilizes SW reentry in 2D cardiac muscle, whereas increased coupling facilitates its early self-termination.
  • Excitation Wave Detachment from Structural Discontinuities Leading to Generation of Rotors by Enhancement of Gap Junctional Coupling in Rabbit Ventricles, Yoshio Takemoto, Haruo Honjo, Takanari Hiroki, Sara Kato, Tomoyuki Suzuki, Yasunori Kushiyama, Norihiro Ueda, Itsuo Kodama, Ichiro Sakuma, Kaichiro Kamiya, journal of arrhythmia, 27, (4) ,   2011年, 査読有り, Introduction: We have reported that enhancement of gap junctional (GJ) coupling destabilizes 2-D spiral-wave reentry and facilitate its termination through the inhibition of wavefront propagation with high curvature. However the effect of GJ enhancement on excitation waves in ventricles with structural discontinuities is unknown. Methods: 2-D ventricular myocardium of perfused rabbit hearts (n=9) was prepared, and a linear cryolesion was made parallel to the fiber orientation. Electrical stimulation was applied next to the lesion (2.5-12 Hz) and the dynamics of U-turning excitation waves were analyzed by high-resolution optical mapping. Results: Rotigaptide (RG, 0.1 μM) significantly increased conduction velocity (by 12 ±3 % and 13 ±6 % along and across the fiber direction at 6.7 Hz, n=10) in ventricles without cryolesion. In the presence of RG, high frequent stimulation (8-12Hz) increased the incidence of wavefront-detachments from the edge of the incision compared to controls (5/9 hearts vs. 2/9 hearts) and rotors were formed behind the barrier. Conclusions: The enhancement of GJ coupling facilitates detachment of excitation waves from structural discontinuities and creates rotors. Wavefront detachment may help termination of anatomical reentry, whereas rotor generation may initiate functional reentry. © 2011, Japanese Heart Rhythm Society. All rights reserved.
  • 混合正規分布による心電図T波の近似とQT間隔の自動計測への応用, 日比野 新, 中杤 昌弘, 植田 典浩, 堀場 充, 安井 健二, 鏡原 有祐, 寺澤 敏昭, 神谷 香一郎, 児玉 逸雄, 松原 充隆, 本多 裕之, 生体医工学, 48, (4) 359 - 367,   2010年08月, 査読有り, 音声認識で用いられるEM(Expectation Maximization)アルゴリズムを使用し、複数の正規分布を組み合わせた混合正規分布で心電図波形を近似することで、より簡便で精度の高いT波終点の自動決定法を確立し、医師の診断支援システムを構築した。健常男性50例を対象に安静時心電図を記録し、得られたの135例の心電図データを採用した。T波の波形は全例において陽性波で、平低化しているものや陰性波、二相性波などはみられなかった。T波の波高は88〜610μVで、平均307.7±133.6μVであった。閾値を元に各サンプルの近似曲線からT波終点の初期推定点を決定し、初期推定点と専門医の計測位置との誤差は絶対値で5.4±43ms、最大で20msの誤差が存在した。重回帰分析で推定された最終推定点と専門医の計測による終点との平均絶対誤差は5.0±3.8msとなり、最大誤差は17.4msまで減少した。
  • Midkine gene transfer after myocardial infarction in rats prevents remodelling and ameliorates cardiac dysfunction, Arihiro Sumida, Mitsuru Horiba, Hisaaki Ishiguro, Hiroharu Takenaka, Norihiro Ueda, Hiroaki Ooboshi, Tobias Opthof, Kenji Kadomatsu, Itsuo Kodama, CARDIOVASCULAR RESEARCH, 86, (1) 113 - 121,   2010年04月, 査読有り, We have previously reported that therapy with midkine (MK) has a protective effect in mouse models of myocardial infarction (MI) and ischemia/reperfusion. The underlying mechanism was proved to be anti-apoptosis and prevention of left ventricular (LV) remodelling following angiogenesis. Here we investigated the effects of overexpression of MK by adenoviral gene transfer on cardiac function and remodelling in an experimental rat MI model.MI was created in male Wistar rats. Adenoviral vectors encoding mouse MK (AdMK) or beta-galactosidase (AdLacZ; as controls) were injected in myocardium at the onset of MI. One week after injection, in vivo adenoviral gene expression was assessed by western blot and histological analysis. After echocardiographic analysis at 4 weeks and haemodynamic analysis at 6 weeks after MI, AdMK animals had better cardiac function compared with AdLacZ animals. Heart weight (HW) and relative HW of AdMK animals were not different from sham-operated animals after 6 weeks, pointing to a very potent effect in the prevention of ischemic cardiomyopathy. In histological studies at 6 weeks after MI, AdMK animals had less fibrosis in the non-infarcted myocardium and higher vascular density in the border-zone area compared with AdLacZ animals. AdMK animals had strongly upregulated levels of phosphorylated extracellular signal-regulated kinase, Akt, PI 3-kinase, and Bcl-2, whereas the level of Bax was downregulated compared with AdLacZ animals.Overexpression of MK prevents LV remodelling and ameliorates LV dysfunction by anti-apoptotic and pro-angiogenic effects. MK gene transfer may provide a new therapeutic modality in ischemic cardiomyopathy and ischemic heart failure.
  • Approximation of ECG T wave by using Gaussian mixtures and automatic measurement of QT interval, Shin Hibino, Masahiro Nakatochi, Norihiro Ueda, Mitsuru Horiba, Kenji Yasui, Yuusuke Kagamihara, Toshiaki Terazawa, Kaichiro Kamiya, Itsuo Kodama, Michitaka Matsubara, Hiroyuki Honda, Transactions of Japanese Society for Medical and Biological Engineering, 48, (4) 359 - 368,   2010年, 査読有り, The purpose of this study is to establish the accurate automated QT measurement system for detecting drug-induces QT interval prolongation. One hundred and thirty five electrocardiograms (ECGs) were recorded from fifty healthy men. We applied Gaussian mixture model to approximate the ECG trace with split and merge expectation maximization (SMEM) algorithm for optimal model parameters. Lead II ECG trace from the beginning of a T wave to the end of subsequent beats P wave was approximated by six Gaussian functions with SMEM algorithm. The end of T wave from original ECG was registered by an experienced cardiologist and corresponding point on the approximated ECG trace was defined as a reference point. A primary estimated point for the end of T wave was selected by using a threshold that was the averaged height differences between the reference point and the 2 ms preceding point. The averaged interval in absolute value between the estimated point and the reference point was 5.4 ± 4.3 ms. Furthermore, it was diminished to 5.0 ± 3.8 ms by multiple regression model analysis (Dependent variable: the reference point as the end of T wave. Independent variables: the primary estimated point as the end of T wave and the each height associated with the fourth and the sixth Gaussian function). The final estimated QT interval and the reference QT interval were 399.2 ± 27.2 ms and 399.2 ± 28.0 ms, respectively. We conclude that our system is able to measure QT interval correctly.
  • T-type Ca2+ channel blockers prevent cardiac cell hypertrophy through an inhibition of calcineurin-NFAT3 activation as well as L-type Ca2+ channel blockers, Mitsuru Horiba, Takao Muto, Norihiro Ueda, Tobias Opthof, Keiko Miwa, Mayumi Hojo, Jong Kook Lee, Kaichiro Kamiya, Itsuo Kodama, Kenji Yasui, Life Sciences, 82, (11-12) 554 - 560,   2008年03月12日, 査読有り, T-type Ca2+ channels (TCCs) are involved in cardiac cell growth and proliferation in cultured cardiomyocytes. Underlying molecular mechanisms are not well understood. In this study, we investigated the role of TCCs in signal transduction in cardiac hypertrophy compared with L-type Ca2+ channels (LCCs). Cardiomyocytes dissociated from neonatal mouse ventricles were cultured until stabilization. Cell hypertrophy was induced by reapplication of 1% fatal bovine serum (FBS) following a period (24 h) of FBS depletion. Cell surface area increased from 862 ± 73 μm2 to 2153 ± 131 μm2 by FBS stimulation in control (250 ± 1.8%). T-type Ca2+ current (ICaT) was inhibited dose-dependently by kurtoxin (KT) and efonidipine (ED) with IC50 0.07 μM and 3.2 μM, respectively in whole-cell voltage clamp. On the other hand, 1 μM KT which inhibits ICaT over 90% did not effect on L-type Ca2+ current (ICaL). 10 μM ED had the ability of ICaL blockade as well as that of ICaT blockade. 3 μM nisoldipine (ND) suppressed ICaL by over 80%. The increase in cell surface area following reapplication of FBS as observed in control (250 ± 1.8%) was significantly reduced in the presence of 1 μM KT (216 ± 1.2%) and virtually abolished in the presence of 10 μM ED (97 ± 0.8%) and 3 μM ND (80 ± 1.1%). Hypertrophy was associated with an increase in BNP mRNA of 316 ± 3.6% in control and this increase was reduced as well in the presence of 1 μM KT (254 ± 1.8%) and almost abolished in the presence of 10 μM ED (116 ± 1.1%) and 3 μM ND (93 ± 0.8%). Immunolabeling showed that translocation of nuclear factor of activated T cells (NFAT3) into the nucleus in response to FBS stimulation was markedly inhibited by either KT or ED as well as ND. Calcineurin phosphatase activity was upregulated 2.2-fold by FBS, but KT, ED and ND decreased this upregulation (1.7-fold, 0.8-fold, and 0.7-fold with KT, ED and ND respectively). These results suggest that blockade of Ca2+ entry into cardiomyocytes via TCCs may block pathophysiological signaling pathways leading to hypertrophy as well as via LCCs. The mechanism may be the inhibition of calcineurin-mediated NFAT3 activation resulting in prevention of its translocation into the nucleus. © 2007 Elsevier Inc. All rights reserved.
  • Aldosterone modulates If current through gene expression in cultured neonatal rat ventricular myocytes, Takao Muto, Norihiro Ueda, Tobias Opthof, Tomoko Ohkusa, Kohzo Nagata, Shinsuke Suzuki, Yukiomi Tsuji, Mitsuru Horiba, Jong Kook Lee, Haruo Honjo, Kaichiro Kamiya, Itsuo Kodama, Kenji Yasui, American Journal of Physiology - Heart and Circulatory Physiology, 293, (5) H2710 - H2718,   2007年11月, 査読有り, Mineralocorticoid receptor (MR) antagonists decrease the incidence of sudden cardiac death in patients with heart failure, as has been reported in two clinical trials (Randomized Aldactone Evaluation Study and Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study). Aldosterone has been shown to increase the propensity to arrhythmias by changing the expression or function of various ion channels. In this study, we investigate the effect of aldosterone on the expression of hyperpolarization- activated current (If) channels in cultured neonatal rat ventricular myocytes, using the whole cell patch-clamp technique, real-time PCR, and Western blotting. Incubation with 10 nM aldosterone for 17-24 h significantly accelerates the rate of spontaneous beating by increasing diastolic depolarization. If current elicited by hyperpolarization from -50 to -130 mV significantly increases aldosterone by 10 nM (by 1.9-fold). Exposure to aldosterone for 1.5 h increases hyperpolarization-activated cyclic nucleotide-gated (HCN) 2 mRNA by 26.3% and HCN4 mRNA by 47.2%, whereas HCN1 mRNA expression remains unaffected. Aldosterone (24-h incubation) increases the expression of HCN2 protein (by 60.0%) and HCN4 protein (by 84.8%), but not HCN1 protein. MR antagonists (1 μM eplerenone or 0.1 μM spironolactone) abolish the increase of If channel expression (currents, mRNA, and protein levels) by 10 nM aldosterone. In contrast, 1 μM aldosterone downregulated If channel gene expression. Glucocorticoid receptor antagonist (100 nM RU-38486) did not affect the increase of If current by 10 nM aldosterone. These findings suggest that aldosterone in physiological concentrations upregulates If channel gene expression by MR activation in cardiac myocytes and may increase excitability, which may have a potential proarrhythmic bearing under pathophysiological conditions. Copyright © 2007 the American Physiological Society.
  • ICH-E14に基づいた心毒性治験のためのQT計測システム, 武藤 貴雄, 安井 健二, 植田 典浩, 堀場 充, 神谷 香一郎, 児玉 逸雄, 心電図, 27, (1) 83 - 92,   2007年01月, 査読有り, 近年、薬剤誘発性QT延長症候群による突然死が社会的問題となっている。すべての新薬の安全性を確保するために、開発段階で心電図QT間隔を計測する国際的なガイドライン(ICH-E14)が提案されている。われわれはICH-E14に基づいた新しいQT計測システムを開発した。このシステムは、はじめにコンピュータ上で2名の臨床検査技師がQT間隔を判読した後、医師が適切な数値を決定する。このシステムを用いて、健康な男性50名の心電図データを解析し、その有用性を検証した。最終判読者である医師2名のばらつきは0.34msで、同一判読者のばらつきは-0.25msと-0.29msであった。次に、塩酸モキシフロキサシン400mgまたはスパルフロキサシン200mgを内服した健常人男性のQTcを計測したところ、それぞれ8.3±14.5ms,13.0±15.0msと有意なQT延長を示したため、本システムが薬剤によるQT延長評価に有用であると考える。(著者抄録)
  • Coronary occlusion and reperfusion promote early afterdepolarizations and ventricular tachycardia in a canine tissue model of type 3 long QT syndrome, Norihiro Ueda, Douglas P. Zipes, Jiashin Wu, American Journal of Physiology - Heart and Circulatory Physiology, 290, (2) H607 - 12,   2006年02月, 査読有り, Although long QT syndrome (LQTS) and coronary occlusion-reperfusion (O/R) are arrhythmogenic, they affect ventricular action potential duration (APD) differently. In contrast to the prolonged APD in LQTS, ischemia abbreviates APD after a transient prolongation. Thus we hypothesized that the dynamic interactive effects of ischemia and LQTS on APD and its dispersion would affect ventricular arrhythmogenicity. We mapped transmural distribution of action potentials in 6 groups of 10 isolated wedges of canine ventricular walls: LQTS-O/R, LQTS only, and O/R only, with separate groups for pacing cycle lengths (PCL) of 1,000 and 2,000 ms. We created type 3 LQTS with anemone toxin (ATX) II followed >30 min later by arterial occlusion (40 min) and reperfusion (>100 min). Arterial occlusion initially (first 4 min) prolonged and then shortened APD. Early afterdepolarizations (EADs) occurred during the initial 4 min of occlusion in 4 of the 10 LQTS-O/R wedges at PCL of 2,000 ms but not in the other groups. Reperfusion restored APD in the O/R-only groups but caused APD to overshoot its original duration, indicating depressed repolarization reserve, in the LQTS-O/R group. Reperfusion increased the dispersion of APDs and initiated ventricular tachycardia-fibrillation in 7 of 10 and 6 of 10 LQTS-O/R wedges and in 2 of 10 and 1 of 10 O/R-only wedges at PCLs of 1,000 and 2,000 ms, respectively. The LQTS-only wedges exhibited neither EADs nor ventricular tachycardia. We conclude that coronary O/R increased the arrhythmogenicity of LQTS via cumulative prolongation of APD, increase in repolarization dispersion, and suppression of repolarization reserve. Copyright © 2006 the American Physiological Society.
  • Pathophysiological basis for monitoring of whole heart conductance by 2-lead system, Yuichiro Yasuda, Toru Maruyama, Hirofumi Nakamura, Takeshi Arita, Norihiro Ueda, Mine Harada, Circulation Journal, 70, (4) 495 - 501,   2006年, 査読有り, Background: The defibrillation threshold (DFT) is elevated during myocardial ischemia, but the underlying mechanism remains to be elucidated. The hypothesis tested by the present study was that whole heart conductance (WHC) is a determinant of DFT. Methods and Results: WHC was monitored across the longest diameter of the isolated perfused rat heart, using a 2-electrode instrument under various conditions including ischemia-reperfusion (IR). In the control study, WHC was influenced by the conductivity and flow rate of the solution. In IR, WHC decreased immediately after the onset of perfusion arrest in a single exponential manner, then declined again gradually. The second decrease was augmented and accelerated by pretreatment with 1.0 mmol/L heptanol (p<0.005) or high-[Ca2+]e (p<0.001), and was attenuated and delayed by pretreatment with 1.0 μmol/L verapamil (p<0.01). WHC after reperfusion was greater than the pre ischemic level. The postischemic increase in WHC was proportional to the ischemic interval and tissue water content as assessed by desiccation method. Conclusion: Although time-dependent alterations in DFT in ischemic hearts may be attributable at least in part to dynamic changes in WHC, WHC should be interpreted carefully because it reflects many physiological factors such as coronary perfusion, electrical coupling of cardiac myocytes and tissue edema.
  • Effects of ultrasound energy application on cardiac performance in open-chest guinea pigs - An in vivo pilot study, Fumiaki Kuma, Norihiro Ueda, Hiroyuki Ito, Toru Maruyama, Yoshikazu Kaji, Takehiko Fujino, Mine Harada, Circulation Journal, 70, (10) 1356 - 1361,   2006年, 査読有り, Background: Although ultrasound (US) is widely used in cardiology, little is known about the effects of US energy on cardiac performance. This study aimed to investigate the mechanical effects of high-intensity continuous US energy (1.0 MHz with 3 different intensities) on cardiac performance. Methods and Results: Either left ventricular (LV) pressure or aortic blood flow (ABF) was evaluated in open-chest guinea pigs (n=30) under surface ECG monitoring. LV systolic pressure and ABF increased significantly (ie, maximum percent increases in these parameters were 2.5%, 3.1% and 7.1% for LV systolic pressure and 9.4%, 4.9% and 8.8% for mean ABF at intensities of 0.06, 0.67 and 2.90 W/cm 2, respectively). LV end-diastolic pressure was reduced significantly by US (5.3±0.9 to 4.8±0.8, 5.5±1.3 to 4.8±1.0 and 5.8±2.0 to 5.0±1.2 mmHg, respectively), indicating positive inotropic and lusitropic effects and resultant ABF augmentation. Local temperature was not significantly changed. ECG showed neither chronotropic action nor arrhythmogenesis. Conclusions: Although the basic mechanisms of these phenomena remain unclear, this pilot study of the short-term effects of US energy on cardiac performance suggests the possibility of physical therapy for heart failure.
  • A unipolar coronary sinus mapping study of patients with left-sided atrioventricular accessory pathways, Satoko Kubota, Kazuta Nakasuga, Toru Maruyama, Norihiro Ueda, Hiroyuki Ito, Yoshikazu Kaji, Mine Harada, International Heart Journal, 46, (4) 657 - 667,   2005年09月13日, 査読有り, So-called unipolar 'PQS pattern' is widely accepted as a hallmark of successful catheter ablation of the left-sided atrioventricular accessory pathway. However, the unipolar nature of the electrogram and the site-dependent appearance of this characteristic pattern are poorly understood. Therefore, unipolar coronary sinus (CS) mapping was performed using a multipolar fine electrode in patients with Wolff-Parkinson-White (WPW) syndrome associated with an antegrade left-sided accessory pathway (case group) and those with a concealed left-sided accessory pathway or atrioventricular nodal reentrant tachycardia (control group) under sinus rhythm and fixed high right atrial, CS ostial, and distal pacing. In both groups, the unipolar CS atrial electrogram showed intrinsic negative deflection (initial positive followed by negative parts) with considerable variation depending on the recording site. This unipolar configuration of the atrial electrogram was not influenced by different activation sequences during pacing at various sites. The case group exhibited a unipolar 'PQS pattern' at successful ablation sites for the left lateral to anterolateral accessory pathway. However, this was not true for the left posteroseptal accessory pathway, possibly because the negative part of the atrial electrogram distorted the 'PQS pattern' as an intervening dip. In conclusion, the site-dependent variations of the unipolar CS atrial electrogram underlie the limited usefulness of the 'PQS pattern' in left posteroseptal accessory pathway localization. Copyright © 2005 by the International Heart Journal Association.
  • Epicardial but not endocardial premature stimulation initiates ventricular tachyarrhythmia in canine in vitro model of long QT syndrome, Norihiro Ueda, Douglas P. Zipes, Jiashin Wu, Heart Rhythm, 1, (6) 684 - 694,   2004年12月, 査読有り, Objectives: To explore the mechanism, we tested the hypothesis that premature epicardial stimulation transiently increased the dispersion of repolarization leading to VT. Background: Premature stimulation initiated ventricular tachycardia (VT) when applied to the epicardium but not to the endocardium in a canine model of long QT syndrome (LOTS). Methods: We optically mapped action potentials (APs) on the cut-exposed transmural surfaces of isolated wedges of canine ventricular walls perfused with anemone toxin II (ATX-II), which produced type 3 LQTS with an asymmetrical transmural profile of repolarization that was earliest in the epicardium and latest in deep subendocardium. Results: Earliest excitable epicardial stimulation triggered VT in 5 of 18 wedges receiving >5 nmol/L ATX-II by direct activation of epicardium, which delayed repolarization in the still refractory midmyocardium and further enhanced the dispersion of repolarization. These VTs were initiated 197 ± 72 ms (n = 10) after the premature stimulation, from focal regions of earliest repolarization downstream to the steepest local spatial gradients of repolarization, a maintained by new focal activation and reentry. Transmural differences in the cycle lengths of activations altered conduction pathways and resulted in torsades de pointes-like polymorphic VT. In contrast, VTs were not initiated by endocardial stimulation at the same premature intervals or when ATX-II was ≤2.5 nmol/L. Failed VT initiation was associated with significantly lower maximum local gradient of repolarization. Conclusions: Heterogeneic repolarization in LQTS provides a transmural asymmetrical substrate for the earliest excitable epicardial, but not endocardial, stimulation to further delay midmyocardial repolarization and produce a steep spatial gradient of repolarization potential initiating torsades de pointes-like polymorphic VT. © 2004 Heart Rhythm Society. All rights reserved.
  • Functional and transmural modulation of M cell behavior in canine ventricular wall, Norihiro Ueda, Douglas P. Zipes, Jiashin Wu, American Journal of Physiology - Heart and Circulatory Physiology, 287, (6 56-6) H2569 - 75,   2004年12月, 査読有り, Previous studies have demonstrated a discrete population of midmyocardial (M) cells in the ventricular myocardium having excessive action potential duration (APD) prolongation during long activation cycle lengths (CL) and under the influence of APD-prolonging agents. However, M cells have not been found in other studies. Existing explanations for the discrepancies appear inadequate. We hypothesized that instead of being a discrete group, M cell behavior is functional and conditionally expressed. We mapped APDs on the cut-exposed transmural surfaces of arterially perfused ventricular wedges from 26 dogs during Na+ current modification with anemone toxin II (ATX-II). Compared with the endocardium, APDs were not statistically different in the parallel layer having the longest mean APD (APDL) and were significantly shorter in the epicardium in the 26 wedges before ATX-II. ATX-II (>5 nmol/l) prolonged APD heterogeneously (midmyocardium > endocardium > epicardium). The differences increased at longer CLs. ATX-II (20.0 nmol/l) shifted the APDL layer to 32 ± 6.2% (6 wedges, CL: 4,000 ms) of the transmural thickness from the (sub)endocardium (8.6 ± 7.2%, 26 wedges, ATX-II free). We detected the presence of M cell behavior (significantly longer APDs in the APDL layer than in the endocardium and epicardium, P ≤ 0.04, CL: 4,000 ms) in the 18 wedges having ≥ 5 nmol/l ATX-II but not (P > 0.36) in the other 18 wedges having ≤ 2.5 nmol/l ATX-II. Both the position of the APDL layer and presence of M cell-like behavior were modulated by ATX-II. The dynamic spatial modulation indicates that M cell behavior is functional and only becomes manifest under suitable conditions.
  • Prior ischemia enhances arrhythmogenicity in isolated canine ventricular wedge model of long QT 3, Norihiro Ueda, Douglas P. Zipes, Jiashin Wu, Cardiovascular Research, 63, (1) 69 - 76,   2004年07月01日, 査読有り, Objective: Ventricular tachyarrhythmias (VTs) occur frequently in patients having long QT syndrome (LQTS) or after acute myocardial ischemia. However, the synergistic effects of ischemia and LQTS on arrhythmia development are unclear. We evaluated the contribution of a prior episode of ischemia on the arrhythmogenicity of the LQTS. Methods: Using a 256-channel optical mapping system, we mapped action potentials on the cut-exposed transmural surfaces of perfused and preconditioned muscle wedges isolated from canine left ventricular walls and recorded their transmural electrocardiogram (ECG). Results: We observed that 40 min of global ischemia followed by 60 min of reperfusion, at which time action potential duration (APD) and conduction velocity had recovered, significantly enhanced the APD prolongation produced by 20 nmol/l anemone toxin II (ATX-II). Wedges after the above ischemia, reperfusion, and ATX-II procedures had 100% (8/8) occurrences of early afterdepolarizations (EADs) and 87.5% (7/8) occurrences of spontaneous VTs and reentry. We observed epicardial, midmyocardial, and endocardial occurrences of EADs in one, seven, and four wedges, respectively. Focal EADs and reentry were responsible for 73% and 18% of the repetitive activations in the VTs. In contrast, neither EADs nor VTs occurred in eight control wedges following identical procedures except without ischemia, and VT occurred in 20% wedges (2/10) after ischemia and reperfusion but before ATX-II. Conclusion: A prior episode of acute ischemia, even after apparent electrophysiologic recovery, enhances the arrhythmogenicity of LQTS induced by ATX-II through the development of EADs and reentry. © 2004 European Society of Cardiology. Published by Elsevier B.V. All rights reserved.
  • Reentrant atrial tachycardia originating from the superior vena cava, Kazuhiko Okamoto, Hiroyuki Ito, Fumiaki Kuma, Akihiro Koike, Eimei Shimoike, Norihiro Ueda, Toru Maruyama, Yoshikazu Kaji, Takehiko Fujino, Journal of Interventional Cardiac Electrophysiology, 8, (3) 203 - 208,   2003年06月, 査読有り, A 52-years old man with a previous pericardiotomy for idiopathic constrictive pericarditis underwent catheter ablation for drug-resistant atrial tachycardia (AT). The mechanism of the AT was considered as reentry because of resetting response and the entrainment phenomenon during AT. We introduced a 64-electrode basket catheter into the superior vena cava (SVC) during AT to obtain precise mapping. A fractionated potential preceding local atrial electrogram was recorded in the SVC. The earliest activation site of the potential was located at the anterior aspect of the SVC, 2 cm above the SVC-right atrium junction determined fluoroscopically. The fractionated potential at this site preceded the onset of the P wave by 115 msec. Radiofrequency catheter ablation at this site eliminated the tachycardia. At 6 months follow-up, the patient is free of AT. Reentrant AT involving the SVC is a candidate of RF ablation. Multielectrode basket catheter is useful for a detailed mapping of the SVC.
  • 心臓カテーテル検査後に発症したコレステロール塞栓症の1例, 安田 雄一郎, 柳 統仁, 下池 英明, 小池 明広, 大西 康, 植田 典浩, 丸山 徹, 加治 良一, 心臓, 33, (Suppl.3) 30 - 34,   2001年11月, 査読有り, 70歳男.10年前に下壁心筋梗塞を発症,冠動脈造影で左回旋枝に病変を認め内科的に加療された.労作時胸痛が再発し,心臓カテーテル検査で三枝病変への進行を認めた.腎機能低下のため一時的人工透析後,両側足背動脈を触知するが両側先端に紫斑を認めた.好酸球増多と合わせてコレステロール塞栓症を疑い,人工透析と人工呼吸管理を実施した.経過中に播種性血管内凝固症候群を併発し1ヵ月後に死亡した.剖検で大動脈は潰瘍を伴い,粥状硬化,腎・脾・膵・胃にコレステロール塞栓を認め,コレステロール塞栓症と診断した.また,心臓は線維化し,好中球浸潤を認めた
  • シロスタゾールの徐脈性不整脈に対する有効性と安全性, 中須賀 一太, 下池 英明, 植田 典浩, 丸山 徹, 加治 良一, 藤野 武彦, 石原 保之, 馬場 祐三, Therapeutic Research, 22, (4) 787 - 789,   2001年04月, 査読有り, 徐脈性不整脈により意識消失やふらつき,著明な徐脈を認め入院となった10例についてシロスタゾールの有効性と安全性を検討した.保存的治療として本剤は有効であるが,重篤な不整脈を合併することがあるため使用上は注意が必要であると考察した
  • Entrapment of a guide wire by the Chiari network in a patient with ablated idiopathic ventricular tachycardia, Eimei Shimoike, Norihiro Ueda, Toru Maruyama, Yoshikazu Kaji, Yoshiyuki Niho, Journal of Interventional Cardiac Electrophysiology, 5, (2) 219 - 222,   2001年, 査読有り, Using a guide wire before insertion of a sheath is a common procedure with infrequent complications. We report an unusual case of a guide wire having been entrapped by the Chiari network prior to an intended radiofrequency ablation procedure, and which could be observed using intracardiac echocardiography. Using transthoracic echocardiography prior to ablation, this patient had been shown to have a relatively large Chiari network. We caution against using a long guide wire in patients with a large Chiari network.
  • Subthreshold stimulation in three types of reentrant supraventricular tachycardia: Correlation with the results of catheter ablation, N. Ueda, Y. Kaji, T. Maruyama, E. Shimoike, H. Ito, T. Fujino, Y. Niho, M. Harada, Japanese Circulation Journal, 65, (12) 1057 - 1063,   2001年, 査読有り, The effects of subthreshold stimulation (STS) by direct current were investigated in 20 patients with atrioventricular nodal reentrant tachycardia (AVNRT), 27 with atrioventricular reentrant tachycardia (AVRT) and 3 with idiopathic atrial reentrant tachycardia (IART) STS was delivered to each eligible site for ablation prior to radiofrequency application. STS was defined as 'positive' if it could terminate the tachycardia or disrupt the conduction of accessory pathways without myocardial capture and defined as 'negative' if it could not. Radiofrequency ablation was performed irrespective of a positive or negative result from STS and was successful in all 50 patients. Among the 50 successful ablation sites, STS was positive at 26 sites (11 sites in AVNRT, 12 in AVRT and 3 in IART). STS was positive at 4 sites where ablation failed in 3 patients with AVRT and was negative at 8 sites where ablation was successful in 4 patients with AVNRT and 4 with AVRT. The positive and negative predictive value of STS for the detection of the optimal ablation site were, respectively, 100% and 74% in AVNRT, 73% and 72% in AVRT, and both 100% in IART STS-guided mapping is a specific method to predict the successful catheter ablation of reentrant supraventricular tachycardia.
  • ペースメーカー,ICDへの電磁障害 放射線治療におけるペースメーカーと植込み型除細動器への影響について, 植田 典浩, 岡本 和彦, 久間 文明, 小池 明広, 丸山 徹, 加治 良一, 藤野 武彦, 吉中 正則, 泉 隆, 城戸 五郎, 河野 博之, 不整脈, 16, (5) 547 - 551,   2000年12月, 査読有り, ペースメーカー(PM)と植込み型除細動器(ICD)に対する放射線治療の影響について検討すると共に,放射線による障害の予防法についても考察した.PMにおいては放射線照射により様々な影響がみられ,恒久的な障害もみられた.PMが照射野に含まれる場合にはファントムを用いた線量計算により照射野をカットする必要がある.ICDには放射線照射による影響はみられなかったが,高周波によると考えられる誤認識がみられた
  • 第4世代植込み型除細動器(ICD)の短期追跡でみられた問題点, 小池 明広, 中須賀 一太, 吉松 卓也, 久間 文明, 岡本 和彦, 下池 英明, 大西 康, 植田 典浩, 丸山 徹, 加治 良一, 金谷 庄藏, 藤野 武彦, 仁保 喜之, 冨田 幸裕, 安井 久喬, 諸江 一男, 心臓, 32, (Suppl.5) 158 - 164,   2000年12月, 査読有り, 患者は8例(男6,女2).基礎疾患は陳旧性心筋梗塞,心筋症であり,持続性心室頻拍及び心室細動の為にICDが植え込まれた.心機能及びICD作動状況について評価した.その結果,1例は左胸部のペースメーカのため右胸部にICDを植え込んだが,経静脈リードのみでは除細動できず皮下パッチ植込み術を必要とした.本症例以後は左胸部植込み例においても電極を2ヶ所に有する経静脈リードを使用した.フォローアップ期間中に5例で誤作動を認めた.1例で抗頻拍ペーシングによる心室頻拍のaccelerationを認めたが,死亡例はなく心機能にも有意な変化は認められなかった
  • 電極カテーテルの機械的刺激による一過性デルタ波消失と房室ブロックを生じた中中隔副伝導路の1例, 久間 文明, 岡本 和彦, 中須賀 一太, 吉松 卓也, 小池 明広, 下池 英明, 大西 康, 植田 典浩, 丸山 徹, 加治 良一, 仁保 喜之, 金谷 庄藏, 藤野 武彦, 不整脈, 16, (4) 481 - 487,   2000年10月, 査読有り, 症例は15歳男子で発作性上室性頻拍(PSVT)を指摘された.頻拍はベラパミル静注で洞調律に復帰するものの薬物療法で十分な効果が得られずカテーテル・アブレーション(CA)治療のため入院した.12誘導心電図でWPW症候群タイプCと診断された.右大腿静脈と右内頸静脈から挿入したカテーテルを高位右房,ヒス束電位記録部(HBE),右室心尖部および冠静脈洞(CS)に留置し電気生理学的検査を施行した.PSVTは中隔側の副伝導路(AP)を介する房室回帰性頻拍(AVRT)と診断した
  • 閾値下直流刺激を用いた房室結節リエントリー性頻拍のカテーテル・アブレーション至適部位の同定 WPW症候群との比較, 植田 典浩, 下池 英明, 丸山 徹, 加治 良一, 金谷 庄藏, 藤野 武彦, 仁保 喜之, 不整脈, 16, (4) 446 - 452,   2000年10月, 査読有り, 房室結節リエントリー性頻拍(AVNRT)の高周波カテーテル・アブレーション(RFCA)の至適部位を同定する際の閾値下刺激(STS)の有用性について検討した.通常型AVNRT中に直流刺激による検討を行い,RFCAを施行した.WPW症候群(WPWS)に対しても同様の検討を行った.通常型AVNRTの連続15例(男4例・女11例,28〜65歳)を対象とした.同様に房室リエントリー性頻拍(AVRT)中に直流刺激による検討を行いRFCAを施行したWPWSの連続8例(男女各4例,16〜66歳)を対象とした.STSによるRFCA至適部位同定法は不整脈の惹起もみられず安全に施行できた.AVNRTの場合は特異度が非常に高く有用である.しかしWPWSではAVRTを誘発した場合には十分な結果が得られなかった
  • In vivo and in vitro study of radio-frequency application with a new long linear probe: Implication for the maze operation, Eimei Shimoike, Yoshikazu Kaji, Norihiro Ueda, Toru Maruyama, Shozo Kanaya, Yoshiyuki Niho, Journal of Thoracic and Cardiovascular Surgery, 120, (1) 164 - 172,   2000年07月, 査読有り, Background: The maze operation for atrial fibrillation is effective but highly invasive. We tested, both in vitro and in vivo, a new technique for creating long linear atrial lesions with a custom-made, 25-mm long, stainless-steel, linear probe and a corresponding 500-kHz generator for assistance in the maze operation. Methods: In the in vitro study with the isolated canine atria, the power of the delivered radio-frequency energy and the saline irrigating flow rate were changed independently, and the sizes of the lesions were measured. In the in vivo study radio-frequency energy was delivered to 4 portions (ie, the smooth and trabeculated portions of the right and left atria). The sizes of the lesions were measured, and the histologic features of the lesions were examined. Electrical isolation of the right atrial appendage from the remaining right atrium was attempted by using this linear probe. Results: In the in vitro study the size of the lesion became larger as the delivered power was increased, although the lesion was limited when the flow rate was high. In the in vivo study the size of the lesion was equal at the 4 different sites. Histologic examinations demonstrated linear and transmural lesions, and electrophysiologic examinations revealed conduction block between the right atrial appendage and the remaining right atrium. Conclusions: The new original long linear probe was effective for creating transmural linear atrial lesions with the irrigation method, presenting the possibility of an intraoperative technique that mimics the maze procedure.
  • 発作性心房細動に対するDisopyramide反復経口投与の試み, 岡本 和彦, 岸川 敏介, 丸山 徹, 植田 典浩, 加治 良一, 金谷 庄蔵, 藤野 武彦, 仁保 喜之, 石原 保之, Therapeutic Research, 21, (4) 869 - 872,   2000年05月, 査読有り, 発作性心房細動に対するdisopyramideの経口反復投与は重篤な副作用の出現もなく,有効であると考えられた
  • Radiofrequency catheter ablation of upper septal idiopathic left ventricular tachycardia exhibiting left bundle branch block morphology, Eimei Shimoike, Norihiro Ueda, Toru Maruyama, Yoshikazu Kaji, Journal of Cardiovascular Electrophysiology, 11, (2) 203 - 207,   2000年, 査読有り, Idiopathic left ventricular (LV) tachycardia usually exhibits right bundle branch block morphology. There are only a few sporadic cases that exhibit left bundle branch block (LBBB) morphology. We report a patient whose QRS complex during ventricular tachycardia (VT) was relatively narrow (100 msec) and exhibited LBBB (precordial R wave transition between V3 and V4) and a normal frontal plane axis. This VT was ablated successfully by radiofrequency current applied to the LV upper septum, where the earliest endocardial activation was recorded.
  • Influence of right atrial structure on outcome of radiofrequency catheter ablation for common atrial flutter, Y. Ohba, E. Shimoike, N. Ueda, T. Maruyama, Y. Kaji, T. Fujino, Y. Niho, Japanese Circulation Journal, 64, (10) 741 - 744,   2000年, 査読有り, Radiofrequency catheter ablation (RFCA) targeting the cavotricuspid isthmus is usually an effective treatment for common atrial flutter (AFL), except in a small subset of patients and the reason for this has yet to be elucidated. The present study investigated the relationship between the outcome of RFCA for common AFL and the anatomy of the right atrium as seen on angiography. Twenty consecutive patients who underwent RFCA for common AFL were divided into 2 groups according to the results of RFCA. Group A comprised 13 patients whose AFL was abolished, fulfilling the criteria of success by the conventional catheter approach, and group B comprised 7 patients whose AFL could not be abolished according to the criteria for success (n=4) or was abolished following an additional superior vena cava approach (n=3). On angiography, the cavotricuspid isthmus was longer (3.5 ± 0.5 vs 2.2 ± 0.6 cm) and deeper (0.94 ± 0.35 vs 0.49 ± 0.19 cm) in group B than in group A (both p<0.01). The height of the eustachian valve was also greater in group B than in group A (1.4 ± 1.1 vs 0.48 ± 0.48 cm, p<0.02). These results suggest that the anatomical structure of the cavotricuspid isthmus affects the outcome of RFCA for common AFL.
  • Atriofascicular connectionが考えられた後中隔潜在性副伝導路による発作性上室性頻拍の1例, 小池 明広, 金谷 英樹, 岡 素雅子, 大庭 百合賀, 下池 英明, 柳 統仁, 大塚 祥司, 大西 康, 植田 典浩, 野崎 雅彦, 丸山 徹, 加治 良一, 仁保 喜之, 金谷 庄藏, 藤野 武彦, 不整脈, 15, (4) 428 - 432,   1999年10月, 査読有り, 発作性上室性頻拍の25歳男.電気生理学的検査では,房室伝導にjump-upなく非減衰性の室房伝導がみられた.頻拍中は冠状静脈洞入口部に最早期逆行性心房興奮を認め,atrial preexcitation phenomenonが得られたため,後中隔副伝導路の房室回帰性頻拍と診断.しかし傍ヒス束ペーシングに対する刺激-心房伝導時間は,低出力170ms,高出力(ヒス束捕捉時)120msと通常の副伝導路と異なる反応を示した.右後中隔三尖弁輪部の高周波通電より室房伝導は途絶し頻拍誘発不能となった
  • 当教室における高周波カテーテルアブレーション導入以後の心房粗動に対する薬物療法, 丸山 徹, 植田 典浩, 大庭 百合賀, 下池 英明, 金谷 英樹, 久間 文明, 小池 明広, 加治 良一, 仁保 喜之, 循環器科, 46, (2) 227 - 232,   1999年08月, 査読有り, 高周波カテーテルアブレーションが主な治療法として確立しつつある心房粗動においても,高周波カテーテルアブレーション施行後に生じた異なる種類の心房粗動や心房細動,更には上室性期外収縮に対して,薬物療法は依然として重要な役割を担っているといえる
  • Heart rate variability analysis of patients with idiopathic left ventricular outflow tract tachycardia - Role of triggered activity, Eimei Shimoike, Norihiro Ueda, Toru Maruyama, Yoshikazu Kaji, Shozo Kanaya, Takehiko Fujino, Yoshiyuki Niho, Japanese Circulation Journal, 63, (8) 629 - 635,   1999年08月, 査読有り, There have been several reports with respect to idiopathic ventricular tachycardias (VTs) originating from the left ventricular outflow tract (LVOT). A previous report suggested that triggered activity plays a partial role in idiopathic LVOT tachycardia from the electrophysiological as well as the electropharmacological viewpoint. However, the exact role of triggered activity in this type of VT remains unknown. In the present study the relationship of the frequency of premature ventricular contractions (PVCs) and heart rate was examined and heart rate variability (HRV) was analyzed in 2 cases of LVOT tachycardia using 24-h Holter electrocardiographic (ECG) monitoring. The relation between the PVCs frequency and heart rate showed a persistently positive correlation, indicating frequent PVCs as heart rate increased. In HRV analysis, NN50 (%), a time-domain variable of parasympathetic activity, showed no change prior to ventricular arrhythmias. In frequency-domain analysis of HRV, the high frequency (HF) component tended to fall prior to repetitive PVCs and VTs. The ratio of the low frequency to high frequency (LF/HF) components increased prior to single PVCs, repetitive PVCs and VTs. Sympathetic predominance predisposes the genesis of these kinds of arrhythmias originating from the LVOT and it is suggested that triggered activity plays an important role in LVOT tachycardia, at least in its initiation.
  • 弁組織を介した高周波通電による心筋焼灼巣の基礎的検討, 下池 英明, 大庭 百合賀, 植田 典浩, 丸山 徹, 加治 良一, 金谷 庄藏, 藤野 武彦, 仁保 喜之, 不整脈, 15, (3) 324 - 328,   1999年07月, 査読有り, 先端4mmカテーテルを用いて37℃に保たれたTyrode液に浸された状態の摘出ブタ心の僧帽弁近傍の心室筋の比較的平滑な部分について,出力・押し付け圧等の条件を一定にして直接通電と僧帽弁を介した通電を行い焼灼巣の大きさ及び弁に与える影響を検討した.僧帽弁を介しての高周波通電でも心筋焼灼は可能であったが焼灼巣の大きさは直接通電に比べて有意に(p<0.05)小さかった.弁を介する通電においては通電エネルギーを上げると弁の変型を認めた.バルサルバ洞や冠状静脈洞などからの組織を介した通電も有効な場合があると考えられた.WPW症候群において,通電が不成功に終わる可能性として,弁を介して通電している為に十分な焼灼が得られていないことも原因の一つと考えられた
  • ホルター心電図からみた右室流出路起源の心室性不整脈の発生機序の検討, 大庭 百合賀, 下池 英明, 久間 文明, 小池 明広, 金谷 英樹, 柳 統仁, 大塚 祥司, 大西 康, 植田 典浩, 野崎 雅彦, 丸山 徹, 加治 良一, 金谷 庄藏, 藤野 武彦, 仁保 喜之, 心電図, 19, (4) 344 - 350,   1999年07月, 査読有り, 右室流出路に起源を有する単形性心室性不整脈に対して高周波カテーテルアブレーションを施行した10例を対象として,施行前に記録したホルター心電図よりVPC-HR関係を解析した.心拍数の増加と共にVPCが増加する場合を促進型,この正相関関係がみられない場合を非促進型とした.右室流出路中隔側に起源を有するVPCは8例中7例で非促進型,逆に右室流出路自由壁側に起源を有するVPCは2例とも促進型で,中隔側起源より自由壁側起源のVPCの方が有意に高頻度に促進型を呈した.これらの所見は臨床上高頻度にみられる右室流出路起源の心室性不整脈でもその発生機序は単一でなく,中隔側と自由壁側でその発生機序が異なる可能性を示している
  • ヒス束近傍の特発性心室頻拍に対するカテーテルアブレーション, 下池 英明, 大庭 百合賀, 柳 統仁, 大塚 祥司, 大西 康, 植田 典浩, 野崎 雅彦, 丸山 徹, 加治 良一, 高橋 尚彦, 仁保 喜之, 福岡医学雑誌, 90, (4) 132 - 139,   1999年04月, 査読有り, 27歳女.23歳時の検診にて心室頻拍を認め,電気生理学的検査にてイソプロテレノールで誘発される右室流出路起源非持続性心室頻拍と診断された.抗不整脈剤無効のため,平成10年2月アブレーション目的で入院となる.入院時現症,検査所見には異常を認めなかった.心電図・運動負荷心電図にて,左脚ブロック・下方軸の心室性期外収縮と非持続性心室頻拍を認めた.カテーテルアブレーション目的で心室性期外収縮を標的としたペースマッピングを行ったところ,ヒス束電位記録部近傍にて良好なペースマッピングが得られ,同部位での高周波通電により心室性期外収縮は消失した.その後運動・薬剤負荷によっても心室性不整脈は誘発不能となった
  • Radiofrequency catheter ablation of idiopathic right ventricular tachycardia near the His bundle., E. Shimoike, Y. Ohba, N. Yanagi, S. Ohtsuka, Y. Ohnishi, N. Ueda, M. Nozaki, T. Maruyama, Y. Kaji, N. Takahashi, Y. Niho, Fukuoka igaku zasshi = Hukuoka acta medica, 90, (4) 132 - 139,   1999年04月, 査読有り, There are only a few reports on successful radiofrequency catheter ablation of idiopathic right ventricular tachycardia (VT) originating from other sites than right ventricular outflow tract. We report here a case of VT which exhibited an inferior-axis and a left bundle branch block pattern and originated near the His bundle. Using the temperature-controlled ablation catheter, prudent observation of the fluoroscopy and intracardiac electrograms during pacemapping, we successfully ablated the origin of the VT without any conduction disturbance. However, further study is required to determine the effectiveness of catheter ablation and the long term prognosis for this type of VT.
  • 民間航空機搭乗中の機内圧変化と乗客の病態生理学的変化に関する研究(第5報) 動脈血酸素飽和度と自律神経系の変動, 金谷 庄藏, 植田 典浩, 車 忠雄, 大柿 哲朗, 丸山 徹, 加治 良一, 藤野 武彦, 健康科学, 21, 121 - 125,   1999年03月, 査読有り
  • Experimental ablation study using a new long linear probe in isolated porcine hearts, Eimei Shimoike, Norihiro Ueda, Toru Maruyama, Yoshikazu Kaji, Shozo Kanaya, Takehiko Fujino, Yoshiyuki Niho, Japanese Heart Journal, 40, (2) 189 - 197,   1999年03月, 査読有り, We studied a new technique for creating long linear lesions in hearts using a custom-made linear probe. Radiofrequency (RF) energy applications using a 25-mm long stainless steel linear probe and a corresponding 500-kHz energy generator were tested, creating 90 lesions in isolated porcine hearts. The RF current was applied between the linear probe and a large patch electrode attached to the back of the specimen. Three parameters, comprising the power of the delivered energy, the pressure of contact between the probe and the specimen, and the duration of energy delivery were changed independently and the size of the resulting lesions was measured. All 90 lesions were transmural, well demarcated and created by a single stationary RF application. Lesion length and width increased with: 1) increasing power, when the other two parameters were maintained at constant levels, 2) increasing contact pressure, when the other two parameters were maintained at constant levels, and 3) increasing duration of energy delivery when the other two paramaters were maintained at constant levels. The maximum width of the lesions was 3.7 mm. No overheating of any of the specimens was observed. In conclusion, the new original long linear probe used in this study was effective for creating transmural linear lesions, presenting the possibility of a worthwhile contribution to the maze surgical procedure applied to atrial fibrillation.
  • Echocardiographic observation before and after rupture of an aneurysm of the sinus of valsalva associated with ventricular septal defect, E. Shimoike, N. Yanagi, N. Ueda, T. Maruyama, Y. Kaji, T. Fujino, R. Masaki, Y. Niho, S. Kanaya, Journal of Medical Ultrasonics, 26, (11) 1111 - 1117,   1999年, 査読有り, A 22-year-old man was admitted for the evaluation of ventricular septal defect (VSD) associated with aneurysm of the sinus of Valsalva. The diagnosis of an unruptured aneurysm of the right sinus of Valsalva associated with high VSD was confirmed by echocardiography and cineangiography. The patient felt palpitation while awaiting surgery on the outpatient bases 3 weeks after he had been discharged. Echocardiography and ECG monitoring confirmed rupture of the aneurysm of the sinus of Valsalva associated with ventricular arrhythmia. This case demonstrates the usefulness of transthoracic as well as transesophageal echocardiography associated with Doppler color flow mapping in detecting aneurysm of the sinus of Valsalva, and, further, that incidental aneurysm of the sinus of Valsalva is a candidate for emergent open-heart surgery.
  • Radiofrequency catheter ablation of left ventricular outflow tract tachycardia from the coronary cusp: A new approach to the tachycardia focus, Eimei Shimoike, Yasushi Ohnishi, Norihiro Ueda, Toru Maruyama, Yoshikazu Kaji, Journal of Cardiovascular Electrophysiology, 10, (7) 1005 - 1009,   1999年, 査読有り, Introduction: Idiopathic ventricular tachycardia (VT) originating from the left ventricular outflow tract (LVOT) is rare. Previously reported were two cases of LVOT tachycardia which were treated with radiofrequency (RF) catheter ablation through endocardial aortomitral continuity. We report here a case of a repetitive LVOT tachycardia in which the QRS morphology during VT exhibited an atypical left bundle branch block and inferior axis. Pace mapping revealed that the origin of this VT was very close to the left sinus of Valsalva. Transcoronary cusp RF catheter ablation abolished the VT in this patient and is a new approach for the treatment of this kind of VT. The application of this approach to the other types of VT has yet to be determined.
  • Na+-K+ pump inhibition caused by chronic amiodarone in guinea pig myocardium, Toru Maruyama, Norihiro Ueda, Yoshikazu Kaji, Shozo Kanaya, Takehiko Fujino, Yoshiyuki Niho, Heart and Vessels, 14, (5) 216 - 223,   1999年, 査読有り, Although it is known that amiodarone inhibits myocardial Na+-K+ pump activity, the potency and the time course of this inhibition are unknown. The aim of this study was to investigate these aspects with reference to digoxin, using guinea pigs treated with either intraperitoneal amiodarone (20 mg/kg per week, up to 12 weeks, n = 26) or the same amount of vehicle as a control (n = 24). ECG recording and microelectrode experiments were conducted every 2 weeks. QT interval corrected by heart rate and action potential duration were prolonged as a function of the time of exposure to amiodarone. Hyperpolarization observed immediately after the overdrive (1.0 Hz) termination or K+-replenishment following K+-depletion in the presence of 0.1 mM Ba2+ was compared in the amiodarone-treated and untreated groups, as an index of the Na+-K+ pump activity. The resting membrane potential recovery from overdrive-induced depolarization was slower and the amplitude of K+-induced hyperpolarization was smaller in the amiodarone-treated group than in the untreated group. These changes were evident as the chronic amiodarone treatment progressed, although the changes in these parameters were greater in the case of acute application of 50 μM digoxin. In conclusion, this study indicates that treatment with amiodarone for longer than several weeks moderately inhibits the myocardial Na+-K+ pump.
  • 撃発活動によると考えられた左室起源の特発性心室頻拍, 下池 英明, 大庭 百合賀, 柳 統仁, 大塚 祥司, 大西 康, 平松 伸一, 岸川 敏介, 植田 典浩, 野崎 雅彦, 丸山 徹, 加治 良一, 仁保 喜之, 金谷 庄藏, 藤野 武彦, 不整脈, 14, (3) 344 - 348,   1998年08月, 査読有り, 症例1は59歳男で49歳時に持続性の心室頻拍(VT)と診断.VTは下方軸,全胸部誘導でR型の心電図でベラパミルとATPが有効,左室流出路での高周波通電にて消失.症例2は64歳男で近医の心電図にて非持続性VTと診断.VT中の心電図は症例1と同じでイソプロテレノール投与下での心房頻回刺激にて誘発された.症例1と同部位での高周波通電にてVTの頻度は劇的に減少した.この2症例はVT中は共通の心電図所見を呈し,左室流出路(左線維三角)に最早期興奮部位を認め,同部位での高周波通電が有効であった.また電気生理学的,薬理学的所見から機序として撃発活動が考えられた
  • 心筋梗塞・拡張型心筋症以外の基礎心疾患による心室性不整脈に対するアミオダロンの使用経験, 丸山 徹, 平松 伸一, 植田 典浩, Progress in Medicine, 18, (Suppl.1) 599 - 602,   1998年04月, 査読有り
  • Radiofrequency catheter ablation of left ventricular outflow tract tachycardia: Report of two cases, Eimei Shimoike, Yurika Ohba, Nobuhito Yanagi, Shin Ichi Hiramatsu, Norihiro Ueda, Toru Maruyama, Yoshikazu Kaji, Shozo Kanaya, Takehiko Fujino, Yoshiyuki Niho, Journal of Cardiovascular Electrophysiology, 9, (2) 196 - 202,   1998年, 査読有り, Idiopathic ventricular tachycardia (VT) originating from the left ventricular outflow tract (LVOT) is rare. We report two patients whose QRS configuration during VT commonly showed an inferior axis and monophasic R waves in all the precordial leads. The mechanism of these VTs appeared to be triggered activity. From mapping and ablation, the origin of these VTs was determined to be in the most posterior LVOT, corresponding to the aortomitral continuity (left fibrous trigone).

MISC

  • エキスパートコンセンサスステートメント 心電図自動診断の精度評価ならびに有用性向上へのアプローチ(第1報) 心電図自動診断に用いられている診断名・所見名の検討, 加藤 貴雄, 八島 正明, 高橋 尚彦, 渡邉 英一, 池田 隆徳, 笠巻 祐二, 住友 直方, 植田 典浩, 森田 宏, 平岡 昌和, 心電図自動診断を考える会, 心電図, 39, (1) 69 - 84,   2019年03月
  • Roles of late INa-mediated focal electorical activities in ventricular tachyarrhythmia associated with acute myocardial ischemia, T. Ogawa, H. Honjo, M. Yamazaki, R. Niwa, N. Ueda, K. Kamiya, EUROPEAN HEART JOURNAL, 37,   2016年08月
  • Atrial Selectivity in Sodium Channel Block by Amiodarone, Tomoyuki Suzuki, Mikio Morishima, Sara Kato, Yoshio Takemoto, Hiroki Takanari, Norihiro Ueda, Yukiomi Tsuji, Haruo Honjo, Kaichiro Kamiya, BIOPHYSICAL JOURNAL, 104, (2) 133A - 133A,   2013年01月
  • Atrial selectivity in sodium channel block by amiodarone, T. Suzuki, M. Morishima, Y. Kushiyama, S. Kato, Y. Takemoto, H. Takanari, N. Ueda, Y. Tsuji, H. Honjo, K. Kamiya, EUROPEAN HEART JOURNAL, 32,   2011年08月


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