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Dive into the research topics where Yuji Hamazaki is active.

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Featured researches published by Yuji Hamazaki.


Circulation-cardiovascular Imaging | 2011

Association Between Left and Right Atrial Remodeling With Atrial Fibrillation Recurrence After Pulmonary Vein Catheter Ablation in Patients With Paroxysmal Atrial Fibrillation A Pilot Study

Yasushi Akutsu; Kyouichi Kaneko; Yusuke Kodama; Jumpei Suyama; Hui-Ling Li; Yuji Hamazaki; Kaoru Tanno; Takehiko Gokan; Youichi Kobayashi

Background— Left atrial (LA) remodeling is a factor in atrial fibrillation (AF) recurrence after pulmonary vein catheter ablation (CA), but right atrium (RA) remodeling has not been investigated for possible associations to AF recurrence. Methods and Results— Using 64-slice multidetector computed tomography, RA and LA volumes were measured 3-dimensionally before CA in 65 patients with initially proven idiopathic paroxysmal AF (mean age, 60±10 years, 81.5% men). The CA procedure was guided by CARTO Merge atrial electroanatomic mapping. Sixteen patients (24.6%) had AF recurrence within the 6-month period after the CA. The recurrence was associated with a large RA volume [odds ratio, 1.04; 95% confidence interval (CI), 1.02 to 1.07, P<0.0001], a large LA volume with 1.04 [95% CI, 1.01 to 1.06, P=0.002], and low LA mean voltage with 1.03 [95% CI, 1.01 to 1.05, P=0.002]. After adjustment for potential confounding variables, RA and LA volumes remained predictive of AF recurrence. Large atrial volumes (mL) (RA ≥87 or LA ≥99) predicted AF recurrence (sensitivity of RA volume: 81.3% in 13 of 16 patients with AF recurrence; specificity: 75.5% in 37 of 49 patients without AF recurrence; sensitivity of LA volume: 81.3% in 13 of 16 patients with AF recurrence; specificity: 69.4% in 34 of 49 patients without AF recurrence), and the combined estimate of both atrial volumes was incremental and additive prognostic power (sensitivity: 75% in 12 of 16 patients with AF recurrence; specificity: 93.9% in 46 of 49 patients without AF recurrence). Conclusions— Both LA and RA remodeling are equally associated with post-CA AF recurrence.


Jacc-cardiovascular Imaging | 2011

Iodine-123 mIBG Imaging for Predicting the Development of Atrial Fibrillation

Yasushi Akutsu; Kyouichi Kaneko; Yusuke Kodama; Hui-Ling Li; Jumpei Suyama; Akira Shinozuka; Takehiko Gokan; Yuji Hamazaki; Kaoru Tanno; Youichi Kobayashi

OBJECTIVES we investigated whether cardiac sympathetic nervous system (SNS) activity measured by iodine-123 meta-iodobenzylguanidine ((123)I-mIBG) imaging would be associated with both the occurrence of heart failure (HF) and the transit to permanent atrial fibrillation (AF) in patients with paroxysmal AF. BACKGROUND atrial fibrillation occurs suddenly and transiently and can persist, and results in the occurrence of HF. An important feature of AF and HF is their propensity to coexist not only because they share antecedent risk factors, but also because the one may directly predispose the heart to the other. However, a useful modality for predicting the occurrences of both those has not been established in patients with paroxysmal AF. METHODS the (123)I-mIBG scintigraphy was performed to evaluate cardiac SNS activity presented as the heart/mediastinum ratio in 98 consecutive patients (age 66 ± 13 years, 63.3% male) with idiopathic paroxysmal AF and preserved left ventricular ejection fraction (≥ 50%). RESULTS during 4 ± 3.6 years of follow-up, the transit to permanent AF was associated with the occurrence of HF (34.3% in 12 of 35 patients with permanent AF vs. 6.3% in 4 of 63 patients without, p < 0.0001). Lower heart/mediastinum ratio and lower left ventricular ejection fraction were the independent predictors of the transit to permanent AF with adjusted hazard ratios of 3.44 (95% confidence interval [CI]: 1.9 to 6.2, p < 0.0001) and 1.04 (95% CI: 1.01 to 1.08, p = 0.014). Further, these factors and higher plasma brain natriuretic peptide concentration were the independent predictors of the occurrence of HF with permanent AF, with adjusted hazard ratios of 5.08 (95% CI: 1.5 to 17.5, p = 0.011), 1.11 (95% CI: 1.03 to 1.19, p = 0.004), and 1.004 (95% CI: 1.001 to 1.008, p = 0.014). CONCLUSIONS cardiac SNS abnormality was associated with the occurrence of both HF and permanent AF in paroxysmal AF patients, and (123)I-mIBG imaging may be a useful modality for predicting the development of AF.


Coronary Artery Disease | 2003

Hepatocyte growth factor and vascular endothelial growth factor in ischaemic heart disease

Hiroshi Suzuki; Mikitaka Murakami; Makoto Shoji; Yoshitaka Iso; Takeshi Kondo; Masayuki Shibata; Hitoshi Ezumi; Yuji Hamazaki; Shinji Koba; Takashi Katagiri

Background Hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) are endothelial cellspecific growth factors, but the production of these growth factors in cardiomyocytes has also been demonstrated. However, there have been no reports focusing their attention on the changes in these growth factors after coronary intervention. We investigated the time‐course changes of the serum VEGF and HGF levels in angina pectoris (AP) and acute myocardial infarction (AMI). Methods The serum HGF and VEGF levels were measured in 60 patients with AP, in 62 patients with AMI (AP, before heparin administration, and at 24 and 48 hours, and one week after intervention; AMI, before heparin, and at 48 and 72 hours, and one, two, three and four weeks) and in 56 patients with neurocirculatory asthenia as controls. We defined the patients with remodelling who showed an increase in left ventricular end‐diastolic volume index (LVEDVI) in the sub‐acute phase of AMI. Results Hepatocyte growth factor levels in the AP and AMI were significantly higher than that in the control (p<0.0001). The AMI level was also significantly higher than AP (p<0.001). In the AMI and AP, HGF peaked at 48 hours. Vascular endothelial growth factor level in the AMI was significantly higher than that in the control and AP (p<0.0001). In the AMI, VEGF peaked at two weeks. There was a significant positive correlation between the peak VEGF and LVEDVI in the sub‐acute phase of AMI (p = 0.0089, r=0.436). Peak VEGF in the remodelling ( + ) group was significantly higher than that in the remodelling (−) group (p<0.001). In the AP, VEGF was unchanged. Conclusion While both myocardial and vascular damage contribute to an increase in HGF level, vascular damage is not associated with the increase in VEGF. Vascular endothelial growth factor might be related to left ventricular remodelling in the sub‐acute phase of myocardial infarction. Coron Artery Dis 14:301‐307


Thrombosis Research | 2011

Activated inflammatory cells participate in thrombus size through tissue factor and plasminogen activator inhibitor-1 in acute coronary syndrome: Immunohistochemical analysis

Tetsuo Sakai; Shin Inoue; Masatoshi Takei; Genyo Ogawa; Yuji Hamazaki; Hidekazu Ota; Youichi Koboyashi

INTRODUCTION Recent studies have suggested that circulating inflammatory cells augment the growth of thrombus in acute coronary syndrome (ACS). We therefore immunohistochemically analyzed thrombi in aspirates obtained from patients immediately after the onset of ACS. MATERIALS AND METHODS Two hundred twenty samples were studied. Total thrombus area, white thrombus area, and red thrombus area were measured. As antibodies in immunohistochemical staining, myeloperoxidase (MPO), CD66b, CD68, p-selectin, tissue factor (TF) and PAI-1 were employed respectively. RESULTS The ratios of areas of red and white thrombi correlated with whole sample areas of enlarged thrombi (r = 0.48, p < 0.001). The immunohistochemical findings revealed granulocytes and macrophages aggregated around p-selectin-positive platelets that shared the boundary between white and red thrombi, a region where MPO and CD66b expression was abundant in neutrophils. The ratios (%) of MPO- and CD66b-positive cells significantly correlated with whole sample areas (r = 0.50; p < 0.001 and r = 0.49; p < 0.001, respectively). Neutrophils and macrophages within thrombi were positive for TF and PAI-1. Along the boundary between red and white thrombi, TF and PAI-1 positivity coincided with MPO-, CD66b- and CD68-positive cells. The ratios of cells positive for both TF and PAI-1 in this area significantly correlated with the whole sample area (r = 0.43, p < 0.001 and r = 0.60, p < 0.001, respectively). CONCLUSIONS These results suggested that enhanced activation of peripheral neutrophils together with increased TF and PAI-1 expression might comprise a considerable portion of thrombus enlargement.


Coronary Artery Disease | 2014

Five-year follow-up of a giant coronary aneurysm using virtual coronary angioscopy.

Yasushi Akutsu; Youichi Kobayashi; Takehiko Sambe; Toshikazu Kurihara; Kyouichi Kaneko; Yusuke Kodama; Hui-Ling Li; Jumpei Suyama; Yuji Hamazaki; Junya Iwasaki; Takehiko Gokan; Kazuo Itabashi; Katsuji Oguchi; Naoki Uchida; Shin-ichi Kobayashi

Yasushi Akutsu, Youichi Kobayashi, Takehiko Sambe, Toshikazu Kurihara, Kyouichi Kaneko, Yusuke Kodama, Hui-Ling Li, Jumpei Suyama, Yuji Hamazaki, Junya Iwasaki, Takehiko Gokan, Kazuo Itabashi, Katsuji Oguchi, Naoki Uchida and Shinichi Kobayashi, Department of Internal Medicine (Cardiology), Clinical Research Institute for Clinical Pharmacology & Therapeutics, Showa University Karasuyama Hospital, Department of Medicine, Division of Cardiology, Departments of Pediatrics, Radiology and Pharmacology, Showa University School of Medicine, Tokyo, Japan


Circulation | 2011

Pulmonary Vein Obstruction After Catheter Ablation Following Atrial Fibrillation

Yasushi Akutsu; Kyouichi Kaneko; Yusuke Kodama; Hui-Ling Li; Jumpei Suyama; Akira Shinozuka; Takehiko Gokan; Yuji Hamazaki; Kaoru Tanno; Youichi Kobayashi

The patient was 68-year-old man with highly symptomatic paroxysmal atrial fibrillation. Transoesophageal echocardiography was performed to confirm no left atrial embolism, and contrast-enhanced 64-row multidetector computed tomography (MDCT) was performed to clarify the anatomic forms and routes of pulmonary veins (PV) before ablation (Figure 1A). The circumferential ablation procedure was performed using electroanatomical mapping (Figure 1B). Radiofrequency catheter energy was delivered with a closed irrigation cool-tip ablation catheter. The patient was kept on oral anticoagulation with a controlled international normalized ratio between 2 and …


Data in Brief | 2016

Dataset of calcified plaque condition in the stenotic coronary artery lesion obtained using multidetector computed tomography to indicate the addition of rotational atherectomy during percutaneous coronary intervention.

Yasushi Akutsu; Yuji Hamazaki; Teruo Sekimoto; Kyouichi Kaneko; Yusuke Kodama; Hui-Ling Li; Jumpei Suyama; Takehiko Gokan; Koshiro Sakai; Ryota Kosaki; Hiroyuki Yokota; Hiroaki Tsujita; Shigeto Tsukamoto; Masayuki Sakurai; Takehiko Sambe; Katsuji Oguchi; Naoki Uchida; Shinichi Kobayashi; Atsushi Aoki; Youichi Kobayashi

Our data shows the regional coronary artery calcium scores (lesion CAC) on multidetector computed tomography (MDCT) and the cross-section imaging on MDCT angiography (CTA) in the target lesion of the patients with stable angina pectoris who were scheduled for percutaneous coronary intervention (PCI). CAC and CTA data were measured using a 128-slice scanner (Somatom Definition AS+; Siemens Medical Solutions, Forchheim, Germany) before PCI. CAC was measured in a non-contrast-enhanced scan and was quantified using the Calcium Score module of SYNAPSE VINCENT software (Fujifilm Co. Tokyo, Japan) and expressed in Agatston units. CTA were then continued with a contrast-enhanced ECG gating to measure the severity of the calcified plaque condition. We present that both CAC and CTA data are used as a benchmark to consider the addition of rotational atherectomy during PCI to severely calcified plaque lesions.


Clinical Nuclear Medicine | 2009

Thallium-201 and I-123 beta-methyl iodophenyl-pentadecanoic acid dual isotope single photon emission computed tomography for evaluating reperfusion injury after successful reperfusion therapy.

Yasushi Akutsu; Hideyuki Yamanaka; Hideki Nishimura; Yuji Hamazaki; Kyouichi Kaneko; Yusuke Kodama; Hui-Ling Li; Jumpei Suyama; Akira Shinozuka; Takehiko Gokan; Youichi Kobayashi

We report a reperfusion injury after rotational coronary atherectomy (RA) in a 66-year-old man with coronary artery disease. Submaximal exercise with thallium-201 single photon emission computed tomography (SPECT) imaging before reperfusion showed partially reversible perfusion defects in the apex and reversible perfusion defects in the anteroseptal area. Thallium-201 and I-123 beta-methyl iodophenyl-pentadecanoic acid (BMIPP) dual isotope SPECT was performed 5 days before and 1 hour after RA, and 1 month after RA. SPECT images at 1 hour after recovery of no reflow phenomenon after RA revealed enlargement of the defect sizes on thallium-201 and BMIPP uptakes in the anteroseptal area including the apex compared with those before RA. The defect size of thallium-201 uptake was progressively improved on 5 hour delayed redistribution imaging and 1 month after reperfusion compared with that of BMIPP uptake. In conclusion, the changes for the worse of thallium-201 uptake and fatty acid metabolism immediately after the no reflow phenomenon may indicate an injured membrane integrity with altered myocardial metabolism rather than myocardial ischemia. Thallium-201 and I-123 BMIPP dual isotope SPECT is useful for evaluating reperfusion injury after successful reperfusion therapy in a patient with acute coronary syndrome.


Journal of Cardiology | 2018

Thrombomodulin can predict the incidence of second events in patients with acute coronary syndrome: Single-center, retrospective cohort study

Ryota Kosaki; Yoshino Minoura; Kunihiro Ogura; Yosuke Oishi; Lisa Tanaka; Ken Arai; Kosuke Nomura; Koshiro Sakai; Teruo Sekimoto; Tenjin Nisikura; Hiroaki Tsujita; Seita Kondo; Shigeto Tsukamoto; Yuji Hamazaki; Youichi Kobayashi

BACKGROUND Plasma levels of atherothrombosis-related markers such as endothelial biomarkers have been reported to predict the risk of first acute coronary syndrome (ACS) events. Percutaneous coronary intervention (PCI) by balloon angioplasty and stenting established as a treatment for ACS enabled early discharge and early clinic care. The procedure of PCI, however, may itself be associated with arterial injury with endothelial dysfunction. The clinical significance of those biomarkers for second events in patients after PCI has not yet been completely understood to identify patients who need strict follow-up. METHODS After the exclusion of 100 patients (60 deaths during hospitalization, 40 severe renal failure), 400 ACS patients (291 males, 71.1±13.0 years) who had undergone successful PCI followed by biomarker assessment within the first postoperative hour were enrolled. We evaluated atherothrombosis-related biomarkers: thrombomodulin (TM), C-reactive protein (CRP), and D-dimer, prothrombin fragment F1+2, and plasminogen activator inhibitor-1, other than those assessed by routine biochemical tests. The outcome after PCI in ACS patients was assessed by the incidence of major adverse cardiovascular events (MACEs). RESULTS MACEs occurred in 112 patients during the follow-up period (813.9±474.8 days). As in previous reports, patients with MACEs showed decreased left ventricular ejection fraction (LVEF) by echocardiography, elevated brain natriuretic peptide and HbA1c than patients without MACEs. Not only these markers but also TM were significantly associated with MACEs in multivariate analysis. There were no significant correlations between MACEs and CRP. The association between TM and MACEs was especially high (odds ratio 2.73) and unaffected by the stage of cardiac (≤40, 40<LVEF≤55, 55<%) or renal function (≤40, 40<creatinine clearance≤75, 75<ml/min). CONCLUSIONS TM is independently associated with MACEs and may be predictive of second events in patients after PCI for ACS. ACS patients with high TM value need strict follow up.


Geriatrics & Gerontology International | 2018

Small dense low-density lipoprotein cholesterol is a promising biomarker for secondary prevention in older men with stable coronary artery disease: sdLDL for secondary prevention in men

Koshiro Sakai; Shinji Koba; Yuya Nakamura; Yuya Yokota; Fumiyoshi Tsunoda; Makoto Shoji; Yasuki Itoh; Yuji Hamazaki; Youichi Kobayashi

The study objective was to investigate whether small dense low‐density lipoprotein cholesterol (sdLDL‐C) is superior to low‐density lipoprotein cholesterol (LDL‐C) and other biomarkers to predict future cardiovascular events (CE) in secondary prevention.

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