K Matsuo

Nagasaki University, Nagasaki-shi, Nagasaki-ken, Japan

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Publications (34)174.26 Total impact

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    ABSTRACT: Early repolarization pattern is a common ECG finding characterized by J-point elevation and QRS notching or slurring in the inferior and/or lateral leads, yet little is known about its incidence and long-term prognosis in Asian populations. We reviewed all the ECG records of the 5976 atomic-bomb survivors who were examined at least once during our biennial health examination in Nagasaki, Japan, between July 1958 and December 2004. We defined early repolarization pattern as ≥0.1-mV elevation of the J point or ST segment, with notching or slurring in at least 2 inferior and/or lateral leads. We assessed unexpected, cardiac, and all-cause death risk by Cox analysis. We identified 1429 early repolarization pattern cases (779 incident cases) during follow-up, yielding a positive rate of 23.9% and an incidence rate of 715 per 100 000 person-years. Early repolarization pattern had an elevated risk of unexpected death (hazard ratio, 1.83; 95% confidence interval, 1.12 to 2.97; P=0.02) and a decreased risk of cardiac (hazard ratio, 0.75; 95% confidence interval, 0.60 to 0.93; P<0.01) and all-cause (hazard ratio, 0.85; 95% confidence interval, 0.78 to 0.93; P<0.01) death. In addition, both slurring and notching were related to higher risk of unexpected death (hazard ratio, 2.09; 95% confidence interval, 1.06 to 4.12; P=0.03), as was early repolarization pattern manifestation in both inferior and lateral leads (hazard ratio, 2.50; 95% confidence interval, 1.29 to 4.83; P<0.01). Early repolarization pattern is associated with an elevated risk of unexpected death and a decreased risk of cardiac and all-cause death. Specific early repolarization pattern morphologies and location are associated with an adverse prognosis.
    Circulation 06/2011; 123(25):2931-7. · 15.20 Impact Factor
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    ABSTRACT: Elevated plasma testosterone levels are thought to play a role in the male preponderance of cases of Brugada syndrome (BS) and the development of prostate cancer. The 34 Brugada-like electrocardiogram (ECG) cases were identified among 2,681 male survivors of the atomic bomb who had undergone at least 1 biennial health examination between July 1958 and December 1999 in Nagasaki, Japan. They were followed for incident prostate cancer from July 1958 through December 2004, and the risk of prostate cancer for Brugada-like ECG, age, smoking habit, and radiation exposure was analyzed using Cox proportional hazards analysis. Among the men with or without Brugada-like ECG there were 4 (11.8%) and 54 (2.0%) cases of prostate cancer, respectively. With age adjustment there was a higher risk of prostate cancer for Brugada-like ECG (relative risk (RR): 5.42, 95% confidence interval (CI) 1.96-15.00, P=0.001). With further adjustment for smoking habit and radiation dose, Brugada-like ECG remained a significant risk factor for prostate cancer (RR: 6.47, 95%CI 1.97-21.21, P=0.002). Brugada-like ECG confers a higher risk of prostate cancer independent of age, smoking habit, and radiation exposure. Men with a Brugada-like ECG should be regularly examined for prostate cancer and vice versa, especially elderly subjects.
    Circulation Journal 12/2008; 73(1):63-8. · 3.58 Impact Factor
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    ABSTRACT: Although prolonged and fractionated right atrial electrograms have been reported as predictors of the development of chronic atrial fibrillation in patients with paroxysmal atrial fibrillation (PAF), the effects of angiotensin-converting enzyme inhibitor (ACEI) on these electrophysiologic abnormalities remain unknown. The purpose of this study was to evaluate whether ACEI influences these electrophysiologic abnormalities of atrial muscle in patients with PAF. While taking oral ACEI for hypertension, 12 patients (ACEI group) with PAF underwent electrophysiologic study (EPS). Catheter mapping of 12 right atrial sites and right atrial extrastimulation were performed during sinus rhythm. Twenty-four age-matched patients with PAF but not taking oral ACEI were included as a control group. The longest duration of the right atrial electrogram was significantly shorter and the maximum number of fragmented deflections per patient was significantly lower in the ACEI group than in the control group (79 +/- 15 ms vs 100 +/- 15 ms, P < 0.005; 5.5 +/- 1.9 vs 7.9 +/- 2.4, P < 0.001, respectively). The number of abnormal atrial electrograms per patient was significantly lower in the ACEI group than in the control group (0.5 +/- 1.4 vs 2.1 +/- 1.8, P < 0.05). The percentage of patients with at least one abnormal atrial electrogram was significantly lower in the ACEI group than in the control group (16.7% vs 79.2%, P < 0.0005). ACEI use is associated with a decrease in the incidence of prolonged and fractionated right atrial electrograms in patients with PAF. In addition, we suggest that ACEI may help prevent PAF from becoming chronic.
    Pacing and Clinical Electrophysiology 02/2006; 29(2):164-70. · 1.75 Impact Factor
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    ABSTRACT: The Brugada-type ECG, a terminal r' wave accompanied by ST segment elevation in the right precordial leads, is not a very rare condition. Most of the cases are men in Japan and elsewhere; however, information about the clinical features of these cases is lacking. The aim of this study was to determine the clinical characteristics of subjects with the Brugada-type ECG, specifically Japanese men. We extracted male Brugada-type ECG cases from 3,374 men followed biennially from 1958 through 2001 in Nagasaki, Japan, and compared the clinical characteristics at diagnosis between these cases and four age-matched male controls for each case. A total of 34 cases with the Brugada-type ECG were observed during follow-up. Body mass index (BMI) at diagnosis was significantly lower in Brugada-type ECG cases than in 136 controls (20.2 +/- 2.1 kg/m(2) vs 21.8 +/- 2.8 kg/m(2), P = 0.003). The BMI trend in cases was always lower than that in controls throughout the 8-year observation period (from 4 years before diagnosis to 4 years after diagnosis). Pulse rate at diagnosis was also somewhat lower in Brugada-type ECG cases than in controls (68.9 +/- 7.7 beats/min vs 72.7 +/- 11.1 beats/min, P = 0.038). The significance disappeared after controlling for BMI (P = 0.131) or body weight (P = 0.153). The cases with the Brugada-type ECG had lower BMI than controls, leading to a clue to possible basic mechanisms of the Brugada-type ECG with a focus on this association.
    Journal of Cardiovascular Electrophysiology 07/2004; 15(6):653-7. · 3.48 Impact Factor
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    ABSTRACT: Although pacing therapy for sick sinus syndrome (SSS) is established, the risk of developing chronic atrial fibrillation (CAF) makes pacing therapy infeasible in some patients. We evaluated whether electrophysiological characteristics of atrial muscle can serve as predictors of the transition to CAF after pacemaker implantation in patients with SSS. Eighty-nine patients with SSS underwent electrophysiological study before pacing therapy. Catheter mapping of 12 right atrial sites was performed during sinus rhythm during electrophysiological. An abnormal atrial electrogram was defined as having a duration of 100 ms or longer, or eight or more fragmented deflections, or both. Right atrial extrastimulation was also performed for atrial vulnerability. After electrophysiological study, all patients underwent pacemaker implantation and were followed up. During the follow-up period of 85 +/- 50 months, development of CAF was observed in 12 patients (group A). The remaining 77 patients remained in sinus rhythm (group B). There were significantly more abnormal atrial electrograms in group A than group B (2.7 +/- 2.3 vs 0.8 +/- 1.2; P < 0.001). The distribution of abnormal atrial electrograms was also greater in group A; patients in group A had more abnormal atrial electrograms than patients in group B in both the high and middle right atrium (P < 0.005 and P < 0.01, respectively). Kaplan-Meier analysis showed that almost 50% of the paced patients with abnormal atrial electrograms (n = 42) developed CAF (P < 0.005). Our data suggest that the existence of abnormal atrial electrograms is predictive of the transition to CAF in paced patients with SSS.
    Pacing and Clinical Electrophysiology 06/2004; 27(5):644-50. · 1.75 Impact Factor
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    ABSTRACT: We describe two cases of asymptomatic Brugada syndrome that displayed a persistent ECG manifestation, but in which the typical ECG pattern disappeared following surgical castration for prostate cancer. These facts suggest a possible association between manifestation of the Brugada-type ECG pattern and testosterone.
    Pacing and Clinical Electrophysiology 08/2003; 26(7 Pt 1):1551-3. · 1.75 Impact Factor
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    ABSTRACT: Ogawa, M., et al.: Acute Effects of Different Atrial Pacing Sites in Patients with Atrial Fibrillation: Comparison of Single site and Biabrial Pacing. It has been reported that atrial single site or biatrial pacing can suppress the occurrence of AF. However, its mechanism remains unclear. The study population included 32 patients with AF (n = 20: AF group), or without paroxysmal AF (n = 12: control group). The mechanism and efficacy of atrial pacing were investigated by electrophysiological studies to determine which was more effective for suppressing AF induction; single site pacing of the right atrial appendage (RAA) or distal coronary sinus (CS–d), or biatrial (simultaneous RAA and CS–d) pacing. In the AF group, AF inducibility was significantly higher with RAA extrastimulus during RAA (12/20; P < 0.0001) or biatrial paced drive (7/20; P < 0.01) than during CS–d paced drive (0/20). In the control group, AF was not induced at any site paced. In the AF group, the conduction delay and other parameters of atrial vulnerability significantly improved during CS–d paced drive. The atrial recovery time (ART) at RAA and CS–d was measured during each basic pacing mode. ART was defined as the sum of the activation time and refractory period, and the difference between ARTs at RAA and CS–d was calculated as the ART difference (ARTD). The ARTD was significantly longer during RAA pacing in the AF group than in control group (155.0 ± 32.8 vs 128.8 ± 32.9 ms, P < 0.05). In the AF group, ARTDs during biatrial (52.0 ± 24.2 ms) and CS–d pacing (51.7 ± 26.0 ms) were significantly shorter than ARTD during RAA pacing. The CS–d paced drive was more effective for suppressing AF induction than biatrial or RAA paced drive by alleviating conduction delay. CS–d and biatrial pacing significantly reduced ARTD compared with RAA pacing.
    Pacing and Clinical Electrophysiology 07/2003; 24(10):1470 - 1478. · 1.75 Impact Factor
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    ABSTRACT: We describe two cases of asymptomatic Brugada syndrome that displayed a persistent ECG manifestation, but in which the typical ECG pattern disappeared following surgical castration for prostate cancer. These facts suggest a possible association between manifestation of the Brugada-type ECG pattern and testosterone. (PACE 2003; 26[Pt. I]:1551–1553)
    Pacing and Clinical Electrophysiology 07/2003; 26(7p1). · 1.75 Impact Factor
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    ABSTRACT: A 62-year-old woman with Wolff-Parkinson-White syndrome had two types of tachycardia; ectopic AT and orthodromic-type AVRT. A radiofrequency application 2 cm inside the coronary sinus ostium eliminated ectopic AT and accessory pathway conduction at once.
    Pacing and Clinical Electrophysiology 02/2003; 26(1 Pt 1):108-9. · 1.75 Impact Factor
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    ABSTRACT: This study evaluates whether electrophysiologic abnormalities in patients with idiopathic paroxysmal atrial fibrillation (PAF) predict the transition to chronic atrial fibrillation (CAF). Ninety-six patients with idiopathic PAF underwent electrophysiologic study and were followed up. During electrophysiologic study, endocardial mapping was performed at 12 sites in the right atrium (four aspects of the high, middle, and low right atrium). During follow-up of 60 to 130 months, conversion from PAF to CAF was observed in 17 patients (CAF group). The remaining 79 patients remained in sinus rhythm (PAF group). Although a high frequency of abnormal atrial electrograms was observed in the high right atrium in both groups, the frequency of those recorded from the middle right atrium was significantly higher in the CAF group than in the PAF group (70.6% vs 13.9%, P < 0.0005). Kaplan-Meier analysis showed that >50% of the patients with abnormal atrial electrograms in the middle right atrium developed CAF after 10 years, whereas only 7% of patients without those developed CAF (P < 0.0001). Our data suggest that extended distribution of abnormal atrial electrograms from the high to middle right atrium is predictive of the development of CAF in patients with idiopathic PAF.
    Journal of Cardiovascular Electrophysiology 11/2002; 13(10):996-1002. · 3.48 Impact Factor
  • Kiyotaka Matsuo, Katsusuke Yano
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    ABSTRACT: Brugada syndrome is characterized by an ECG pattern of right bundle branch block and ST-segment elevation in right precordial leads, and sudden death caused by ventricular fibrillation(VF). The cellular basis for the syndrome is thought to be due to an outward shift in the ionic current active during phase 1 of the right ventricular epicardial action potential. Mutations of the cardiac sodium channel gene, SCN5A, have been identified as the genesis of the syndrome. This ECG pattern, which appears intermittently in most patients, is accentuated just before and after episodes of VF and is unmasked by class IA and IC antiarrhythmic agents. Development of VF is associated with an increase in vagal activity, and it occurs frequently during sleep. Implantable-cardioverter defibrillator is the effective therapy for prevention from sudden death.
    Nippon rinsho. Japanese journal of clinical medicine 08/2002; 60(7):1408-14.
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    ABSTRACT: The study examined the electrocardiographic and electrophysiologic characteristics in relation to programmed ventricular stimulation (PVS)-induced ventricular fibrillation (VF), as well as the implications of PVS-induced VF on the recurrence of cardiac events in symptomatic Brugada syndrome. Brugada syndrome is characterized by ST-segment elevation in the right precordial leads (V(1)-V(3)) and an episode of VF. Thirty-four symptomatic patients with Brugada syndrome (33 men and 1 woman; 44 +/- 12 years old) were classified into two groups according to the inducibility of VF with PVS: 22 patients with induced VF requiring direct cardioversion for termination (Induced VF group) and 12 patients without induced VF (Noninduced VF group). The induced VF group showed a longer QRS duration, a higher incidence of right bundle branch block and late potentials detected on the signal-averaged electrocardiogram, longer His-ventricular intervals and a longer conduction time from the RVOT to the left ventricle at extrastimulation than those in the non-induced VF group. However, there was no significant difference in the recurrence of cardiac events (VF documented by an implantable cardioverter-defibrillator and sudden cardiac death) between the two groups (8 [36%] of 22 patients vs. 7 [58%] of 12 patients) during long-term follow-up (range 1 to 149 months; mean 38). Our data suggest that induction of VF by PVS depends on the severity of depolarization abnormalities but does not predict the recurrence of cardiac events in symptomatic Brugada syndrome, indicating that both depolarization and repolarization abnormalities are important in the development of VF.
    Journal of the American College of Cardiology 07/2002; 39(11):1799-805. · 14.09 Impact Factor
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    ABSTRACT: Several local electrogram characteristics have been proposed as criteria to predict successful ablation. However, poor specificity due to obscuration of the retrograde atrial electrogram by the ventricular electrogram is problematic. The aim of this study was to analyze local electrograms obtained by simultaneous pacing to identify quantitative criteria that may predict successful ablation sites for concealed left free-wall accessory pathways. Twenty-four local electrograms from 10 successful and 14 unsuccessful ablation sites in ten patients were analyzed. Retrograde atrial electrograms were confirmed by the simultaneous pacing method. The intervals between the retrograde atrial electrogram of the coronary sinus and the ablation site, the initiation of the ventricular electrogram and the retrograde atrial electrogram, and the stimulus and retrograde atrial electrogram were analyzed. All retrograde atrial electrograms could be confirmed clearly by the simultaneous pacing method. The interval between the retrograde atrial electrogram of the coronary sinus and that of the ablation site was shorter at successful sites than at unsuccessful sites (-7.0 +/- 9.2 ms vs 5.7 +/- 2.7 ms; 95% confidence interval, -18 to -7; P < 0.0001). An interval of < or = 0 ms resulted in 100% sensitivity and 92.7% specificity for success. The other two interval measurements at successful sites did not differ significantly from those at unsuccessful sites. The authors propose an interval of < or = 0 ms between the retrograde atrial electrogram of the coronary sinus and that of the ablation site confirmed by the simultaneous pacing method as a quantitative criterion to identify the successful ablation site for concealed left free-wall accessory pathways. Application of this criterion may reduce the number of unnecessary ablations.
    Pacing and Clinical Electrophysiology 06/2002; 25(6):922-8. · 1.75 Impact Factor
  • K Matsuo, M Akahoshi, E Nakashima
    ACC Current Journal Review 01/2002; 11(1):65–66.
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    Journal of The American College of Cardiology - J AMER COLL CARDIOL. 01/2002; 39:94-95.
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    ABSTRACT: A 41-year-old woman with arrhythmogenic right ventricular dysplasia (ARVD) underwent the implantation of an implantable cardioverter-defibrillator (ICD), in which the defibrillator electrode was unusually located in the right ventricular (RV) outflow tract. Although fractionated electrograms were demonstrated in the RV apex, which is the usual site for ICD electrodes, normal electrograms were recorded in the RV outflow tract during an electrophysiologic study. An electrode with a screw-in tip was used to fix the implant in the RV outflow tract and obtain successful defibrillation. If normal electrograms are recorded in the RV outflow tract, the site may prove to be an alternative location for an ICD electrode even for ARVD patients.
    Japanese Circulation Journal 12/2001; 65(11):994-6.
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    ABSTRACT: It has been reported that a trial single site or biatrial pacing can suppress the occurrence of AF. However, its mechanism remains unclear. The study population included 32 patients with AF (n = 20: AF group), or without paroxysmal AF (n = 12: control group). The mechanism and efficacy of atrial pacing were investigated by electrophysiological studies to determine which was more effective for suppressing AF induction; single site pacing of the right atrial appendage (RAA) or distal coronary sinus (CS-d), or biatrial (simultaneous BAA and CS-d) pacing. In the AF group, AF inducibility was significantly higher with BAA extrastimulus during RAA (12/20; P < 0.0001) or biatrial paced drive (7/20; P < 0.01) than during CS-d paced drive (0/20). In the control group, AF was not induced at any site paced. In the AF group, the conduction delay and other parameters of atrial vulnerability significantly improved during CS-d paced drive. The atrial recovery time (ART) at RAA and CS-d was measured during each basic pacing mode. ART was defined as the sum of the activation time and refractory period, and the difference between ARTs at RAA and CS-d was calculated as the ART difference (ARTD). The ARTD was significantly longer during BAA pacing in the AF group than in control group (155.0 +/- 32.8 vs 128.8 +/- 32.9 ms, P < 0.05). In the AFgroup, ARTDs during biatrial (52.0 +/- 24.2 ms) and CS-d pacing (51.7 +/- 26.0 ms) were significantly shorter than ARTD during RAA pacing. The CS-d paced drive was more effective for suppressing AF induction than biatrial or RAA paced drive by alleviating conduction delay. CS-d and biatrial pacing significantly reduced ARTD compared with RAA pacing.
    Pacing and Clinical Electrophysiology 11/2001; 24(10):1470-8. · 1.75 Impact Factor
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    ABSTRACT: We sought to demonstrate the prevalence, incidence and prognostic value of the Brugada-type electrocardiogram (ECG) in a general population. The Brugada syndrome is characterized by evidence of right bundle branch block and ST segment elevation in the right precordial leads, as well as sudden death caused by ventricular fibrillation. However, the natural history of the Brugada-type ECG remains unclear. We investigated 4,788 subjects (1,956 men and 2,832 women) who were <50 years old in 1958 and had undergone biennial health examinations, including electrocardiography, through 1999. The Brugada-type ECG was defined as a terminal r' wave in lead V(1) and ST segment elevation > or =0.1 mV in leads V(1) and V(2). Unexpected death was defined as sudden death or unexplained accidental death. There were a total of 32 Brugada-type ECG cases; the prevalence and incidence were 146.2 in 100,000 persons and 14.2 persons per 100,000 person-years, respectively. The incidence was nine times higher among men than women, and the average age at presentation was 45 +/- 10.5 years. The Brugada-type ECG appeared intermittently in most cases and was found in 26% of subjects who died unexpectedly. Cox survival analysis revealed that mortality from unexpected death was significantly higher in subjects with a Brugada-type ECG than in control subjects (p < 0.01). Unexpected deaths were more frequent among subjects with the Brugada-type ECG who had a history of syncope (p < 0.05). The Brugada-type ECG is not a very rare condition in the adult Japanese population. Subjects with a Brugada-type ECG have an increased risk of unexpected death.
    Journal of the American College of Cardiology 10/2001; 38(3):765-70. · 14.09 Impact Factor
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    ABSTRACT: We report a patient with a complex nonreentrant supraventricular tachycardia because of double ventricular response resulting from antegrade dual atrioventricular (AV) nodal pathways. We could induce double ventricular response and confirm dual AV nodal pathways by AV simultaneous pacing during basic stimulation proceeding with programmed atrial single extrastimulation. As far as we know, it is the first report about the application of the AV simultaneous basic stimulation to prove the sustained nonreentrant tachycardia because of simultaneous conduction over dual AV nodal pathways. This was also confirmed by absence of the arrhythmia immediately after the elimination of the slow pathway conduction by radiofrequency ablation.
    Journal of Electrocardiology 02/2001; 34(1):59-63. · 1.09 Impact Factor
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    ABSTRACT: OBJECTIVESWe sought to demonstrate the mode of spontaneous onset of ventricular fibrillation (VF) in patients with Brugada syndrome.BACKGROUNDThe electrophysiologic mechanisms of VF in Brugada syndrome have not been fully investigated.METHODSNineteen patients (all male, mean age 47 ± 12 years) with Brugada syndrome were treated with an implantable cardioverter defibrillator (ICD). The implanted devices were capable of storing electrograms during an arrhythmic event. We investigated the mode of spontaneous onset of VF according to the electrocardiographic features during the episode of VF, which were obtained from stored electrograms of ICDs and/or electrocardiographic (ECG) monitoring.RESULTSDuring a follow-up of 34.7 ± 19.4 months (range 14 to 81 months), 46 episodes of spontaneous VF attacks were documented in 7/19 (37%) patients. The event-free period between ICD implantation and the first spontaneous occurrence of VF was 14.6 ± 12.1 months (range 3.7 to 27.4 months). We investigated 33/46 episodes of VF, for which electrocardiographic features (10 to 20 s before and during VF) were obtained from ICDs and/or ECG monitoring in five patients. A total of 22/33 episodes of VF were preceded by premature ventricular contractions (PVCs), which were almost identical to the initiating PVCs of VF. Furthermore, in three patients who had multiple VF episodes, VF attacks were always initiated by the same respective PVC. The coupling interval of the initiating PVCs of VF was 388 ± 28 ms.CONCLUSIONSSpontaneous episodes of VF in patients with Brugada syndrome were triggered by specific PVCs. These findings may provide important insights into the pathophysiological mechanisms causing VF in Brugada syndrome.
    Journal of the American College of Cardiology 12/2000; · 14.09 Impact Factor

Publication Stats

832 Citations
174.26 Total Impact Points

Institutions

  • 2000–2006
    • Nagasaki University
      • • Department of Cardiovascular Medicine
      • • Department of Internal Medicine
      Nagasaki-shi, Nagasaki-ken, Japan
  • 2003–2004
    • Radiation Effects Research Foundation
      Hirosima, Hiroshima, Japan
  • 1994–2003
    • Nagasaki University Hospital
      Nagasaki, Nagasaki, Japan
  • 1998–2001
    • National Cerebral and Cardiovascular Center
      • Department of Cardiovascular Medicine
      Ōsaka-shi, Osaka-fu, Japan
  • 1995
    • Teikyo University
      Edo, Tōkyō, Japan