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Dive into the research topics where Naka Sakamoto is active.

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Featured researches published by Naka Sakamoto.


Journal of Cardiovascular Electrophysiology | 2012

Enhanced transmural dispersion of repolarization in patients with J wave syndromes.

Ahmed Karim Talib; Nobuyuki Sato; Naka Sakamoto; Yasuko Tanabe; Toshiharu Takeuchi; Yasuaki Saijo; Yuichiro Kawamura; Naoyuki Hasebe

J Wave Syndromes. Introduction: Recently, great attention has been paid to the risk stratification of asymptomatic patients with an electrocardiographic early repolarization (ER) pattern. We investigated several repolarization parameters including the Tpeak‐Tend interval and Tpeak‐Tend/QT ratio in healthy individuals and patients with J wave syndrome who were aborted from sudden cardiac death.


Heart Rhythm | 2015

Late gadolinium enhancement on cardiac magnetic resonance represents the depolarizing and repolarizing electrically damaged foci causing malignant ventricular arrhythmia in hypertrophic cardiomyopathy

Naka Sakamoto; Yuichiro Kawamura; Nobuyuki Sato; Asami Nimura; Motoki Matsuki; Atsushi Yamauchi; Takayasu Kanno; Yasuko Tanabe; Toshiharu Takeuchi; Shunsuke Natori; Yasuaki Saijo; Tamio Aburano; Naoyuki Hasebe

BACKGROUND The presence of a myocardial scar detected by late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) has been described as a predictor of all-cause mortality in hypertrophic cardiomyopathy (HCM). However, the detailed spatial relationship between LGE site and electrical abnormality is unclear in high-risk HCM with malignant arrhythmia. OBJECTIVE The purpose of this study was to elucidate the detailed relationship between the site on CMR imaging and the electrically damaged site, a potential origin of ventricular arrhythmias in patients with HCM. METHODS Fifty consecutive HCM patients underwent contrast-enhanced CMR. Of those patients, 18 patients with ventricular tachycardia underwent electrophysiology study including endocardial mapping of the left ventricle (LV). The LGE area was calculated at 12 different LV sites: anterior, lateral, posterior, and septal segments of the basal, middle, and apical portions. At each LV site, the bipolar electrogram, effective refractory period (ERP), and monophasic action potential were recorded. RESULTS LGE-positive segments demonstrated a significantly lower amplitude (4.0 ± 2.8 mV vs 7.3 ± 3.6 mV; P < .001), longer duration (54.7 ± 17.8 vs 40.6 ± 7.8 ms; P < .001), longer ERP (320 ± 42 ms vs 284 ± 37 ms; P = .001), and longer monophasic action potential duration measured at 90% repolarization (321 ± 19 ms vs 283 ± 25 ms; P < .001) than did LGE-negative segments. The LGE area negatively correlated with the amplitude (r = -0.59; P < .001) and positively correlated with the duration (r = 0.64; P < .001), ERP (r = 0.44; P < .001), and action potential duration measured at 90% repolarization (r = 0.63; P < .001). All the observed VTs originated from LGE-positive segments. CONCLUSION The spatial distribution of LGE significantly correlates with depolarizing and repolarizing electrical damage in high-risk HCM with malignant ventricular arrhythmia.


Heart Rhythm | 2015

Late gadolinium enhancement of cardiac magnetic resonance imaging indicates abnormalities of time-domain T-wave alternans in hypertrophic cardiomyopathy with ventricular tachycardia

Naka Sakamoto; Nobuyuki Sato; Kensuke Oikawa; Ahmed Karim Talib; Eitaro Sugiyama; Akiho Minoshima; Yasuko Tanabe; Toshiharu Takeuchi; Kazumi Akasaka; Yasuaki Saijo; Yuichiro Kawamura; Naoyuki Hasebe

BACKGROUND The presence of myocardial scar detected by late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) imaging has been described as a good independent predictor of mortality in patients with hypertrophic cardiomyopathy (HCM). Time-domain T-wave alternans (TWA) is also a potential predictor of cardiac mortality in patients with left ventricular dysfunction. OBJECTIVE The purpose of this study was to elucidate the relationship between LGE distribution and TWA in patients with HCM. METHODS CMR and TWA analyses using Holter monitoring were performed in 42 patients with HCM. The average transmural extent of LGE was scored as 1-4 in each segment, and the sum of the LGE scores (total LGE score) was calculated for each patient. The correlation between the maximal time-domain TWA voltage and LGE findings was analyzed, and the differences in time-domain TWA voltage, total LGE score, and cardiac function assessed by CMR imaging in the presence or absence of ventricular tachycardia (VT) were also compared. RESULTS The total LGE score was significantly and positively correlated with the maximal time-domain TWA voltage (r = 0.59; P < .001). Furthermore, the total LGE score and maximal time-domain TWA voltage were significantly greater in patients who had episodes of VT (n = 21) than in those without VT (23 ± 7 vs. 10 ± 8; P < .001 and 87 ± 26 μV vs. 62 ± 12 μV; P < .001, respectively). However, the left ventricular ejection fraction did not statistically differ between patients with VT and those without VT (56% ± 14% vs. 61% ± 7%; P = .102). CONCLUSION The magnitude of the localized LGE was significantly correlated with abnormalities in ventricular repolarization as assessed by TWA and QT dispersion.


Heart and Vessels | 2014

Three cases of corticosteroid therapy triggering ventricular fibrillation in J-wave syndromes

Naka Sakamoto; Nobuyuki Sato; Masahide Goto; Motoi Kobayashi; Naofumi Takehara; Toshiharu Takeuchi; Ahmed Karim Talib; Eitaro Sugiyama; Akiho Minoshima; Yasuko Tanabe; Kazumi Akasaka; Jun-ichi Kawabe; Yuichiro Kawamura; Atsushi Doi; Naoyuki Hasebe

We describe three cases of J-wave syndrome in which ventricular fibrillation (VF) was probably induced by corticosteroid therapy. The patients involved were being treated with prednisolone for concomitant bronchial asthma. One of the three patients had only one episode of VF during her long follow-up period (14 years). Two patients had hypokalemia during their VF episodes. Corticosteroids have been shown to induce various types of arrhythmia and to modify cardiac potassium channels. We discuss the possible association between corticosteroid therapy and VF in J-wave syndrome based on the cases we have encountered.


Journal of Arrhythmia | 2018

Japanese Antibacterial Drug Management for Cardiac Sarcoidosis (J-ACNES): A multicenter, open-label, randomized, controlled study

Kohei Ishibashi; Yoshinobu Eishi; Nobuhiro Tahara; Masanori Asakura; Naka Sakamoto; Kazufumi Nakamura; Yoichi Takaya; Tomohisa Nakamura; Yoshikazu Yazaki; Tetsuo Yamaguchi; Koko Asakura; Toshihisa Anzai; Teruo Noguchi; Satoshi Yasuda; Fumio Terasaki; Toshimitsu Hamasaki; Kengo Kusano

Cardiac sarcoidosis (CS) is a noncaseating granulomatous disease of unknown etiology. Lifelong immunosuppressive therapy, most frequently using corticosteroids, is a standard therapy to control hypersensitivity of immune reactions and prevent inflammation. However, it sometimes causes various systemic adverse effects and requires dose escalation. Thus, additional therapy may be required for the treatment of this disease. Recently, Propionibacterium acnes (P. acnes) was reported as one of the etiologic agents of CS, indicating that antibacterial drugs (ABD) may be effective for the treatment of CS. The objective of this study was to investigate the effect of ABD treatment, in addition to standard corticosteroid therapy, in patients with CS.


Magnesium Research | 2015

The relationship between repolarization parameters and serum electrolyte levels in patients with J wave syndromes

Nobuyuki Sato; Rie Sasaki; Marina Imahashi; Eisuke Ito; Kumiko Saito; Haruyo Kubota; Ahmed Karim Talib; Naka Sakamoto; Kazumi Akasaka; Yasuaki Saijo; Yuichiro Kawamura; Satoshi Fujii; Naoyuki Hasebe

BACKGROUND Intravenous administration of magnesium (Mg(2+)) is effective for polymorphic ventricular tachycardia via homogenization of transmural ventricular repolarization. Mg(2+) likely plays some role in the heterogeneity of repolarization in J wave syndromes. OBJECTIVE To investigate the relationship between the repolarization parameters and serum Mg(2+), potassium (K(+)), and calcium (Ca(2+)) levels in J wave syndromes. METHODS Thirteen J-wave syndrome patients (Brugada and early repolarization [ER] syndromes), with documented episodes of ventricular fibrillation (VF), and 13 ER pattern (ERP) or Brugada type ECG patients were enrolled (25 males, mean age 48 ± 15 years). The 12-lead ECG-derived parameters including the QT, QT dispersion (QTd), Tpeak-Tend (Tp-e) interval, Tp-e dispersion (Tp-ed), Tp-e/QT ratio, and activation recovery interval (ARI) dispersion were calculated; the correlations between these parameters and electrolytes including Mg(2+), K(+), and Ca(2+) were analyzed. RESULTS Although there was no association between serum K(+) or Ca(2+) and QTd, there was a strong negative correlation between serum Mg(2+) and QTd in J wave syndrome patients with a history of VF (r = -0.715, p = 0.006). Also, there was a tendency for a negative correlation between Mg(2+) and Tp-ed or ARI dispersion in J wave syndrome patients with a history of VF (r = -0.513, p = 0.072 and r = -0.53, p = 0.063, respectively). On the other hand, in 13 patients with a Brugada type ECG or ERP, no correlation was observed between serum Mg(2+) and the QTd, Tp-ed or ARI dispersion. CONCLUSION Serum Mg(2+) may play an important role in the cardiac repolarization process in J wave syndromes.


Journal of the American College of Cardiology | 2015

A COMBINATION OF 123I-BMIPP SPECT AND STRESS 201TL MYOCARDIAL PERFUSION SPECT AS A USEFUL PROGNOSTIC MARKER OF ASYMPTOMATIC PATIENTS WITH NON-OBSTRUCTIVE HYPERTROPHIC CARDIOMYOPATHY

Toshiharu Takeuchi; Masahide Goto; Makoto Aita; Ayumi Date; Eitaro Sugiyama; Akiho Minoshima; Naka Sakamoto; Yasuko Tanabe; Nobuyuki Sato; Naoyuki Hasebe

Reduced coronary flow reserve (CFR) indicates adverse clinical outcome in hypertrophic cardiomyopathy (HCM). 123I-BMIPP (BMIPP) SPECT and stress 201Tl (TL) SPECT has been used to evaluate coronary microvascular dysfunction in HCM. We investigated the long-term prognostic value of BMIPP and stress TL


Angiology | 1999

Characteristics of Intracardiac Potentials at Successful Ablation Sites in Concealed Wolff-Parkinson-White Syndrome

Yuichiro Kawamura; Nobuyuki Sato; Naka Sakamoto; Ayumi Yokoyama; Shinsuke Kamada; Hiroyuki Kakuchi; Yasuhito Iida; Kenjiro Kikuchi

The authors investigated bipolar electrograms recorded from the catheter tip at the actual successful ablation sites in 22 consecutive patients with concealed Wolff-Parkinson-White syndrome to clarify the characteristics of the potentials indicating the optimal site for catheter ablation. In all patients the retrograde transaortic approach to their left-sided accessory pathways, and a temperature-controlled (60°C) energy delivery, were performed. The authors assumed that a shorter dissociation time (time from energy delivery to ventriculoatrial conduction dissociation) indicated more accurate catheter mapping. A significant negative correlation (r = 0.527, p < 0.05) between the AV ratio (ratio of the amplitudes of the atrial to ventricular potentials) recorded at the ablation catheter tip and the dissociation time was observed. When the AV ratio and the dissoci ation time were compared among the groups classified according to the corresponding Npeak (the number of positive potential peaks in the electrogram obtained from the ablation catheter tip during right ventricular apical pacing) value, they differed signifi cantly (p < 0.05 and p < 0.01, respectively), ie, a higher AV ratio and a shorter dissocia tion time related to a multipeak electrogram from the ablation catheter tip. The authors conclude that the atrial insertion site of the accessory pathway, exhibiting a multipeak complex electrogram that may represent nonuniform anisotropic characteristics, is an adequate ablation site.


International Heart Journal | 2010

Possible Contribution of Ischemia of the Conus Branch to Induction or Augmentation of Brugada Type Electrocardiographic Changes in Patients With Coronary Artery Disease

Masaru Yamaki; Nobuyuki Sato; Takuya Myojo; Takeshi Nishiura; Masato Nishimura; Hideki Nakamura; Motoi Okada; Satoshi Fujita; Kazutomo Go; Naka Sakamoto; Yasuko Tanabe; Toshiharu Takeuchi; Yuichiro Kawamura; Naoyuki Hasebe


Internal Medicine | 2011

A Case of Idiopathic Systemic Capillary Leak Syndrome with High Serum Levels of G-CSF on Exacerbation

Naoki Nakagawa; Hisanobu Ota; Yasuko Tanabe; Maki Kabara; Motoki Matsuki; Junko Chinda; Naka Sakamoto; Takayuki Fujino; Naofumi Takehara; Toshiharu Takeuchi; Jun-ichi Kawabe; Nobuyuki Sato; Yuichiro Kawamura; Takashi Fukuhara; Katsuya Ikuta; Kenjiro Kikuchi; Naoyuki Hasebe

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Naoyuki Hasebe

Asahikawa Medical University

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Yasuko Tanabe

Asahikawa Medical University

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Yuichiro Kawamura

Asahikawa Medical University

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Nobuyuki Sato

Asahikawa Medical University

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Toshiharu Takeuchi

Asahikawa Medical University

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Kenjiro Kikuchi

Asahikawa Medical College

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Masaru Yamaki

Asahikawa Medical College

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Motoki Matsuki

Asahikawa Medical University

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Takayasu Kanno

Asahikawa Medical University

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