Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Naohiko Nemoto is active.

Publication


Featured researches published by Naohiko Nemoto.


American Journal of Cardiology | 2014

Impact of Continuous Deterioration of Kidney Function 6 to 8 Months After Percutaneous Coronary Intervention for Acute Coronary Syndrome

Naohiko Nemoto; Masaki Iwasaki; Mami Nakanishi; Tadashi Araki; Makoto Utsunomiya; Masaki Hori; Nobutaka Ikeda; Kunihiko Makino; Hideki Itaya; Raisuke Iijima; Hidehiko Hara; Takuro Takagi; Nobuhiko Joki; Kaoru Sugi; Masato Nakamura

Preprocedural chronic kidney disease and contrast-induced acute kidney injury are predictors of in-hospital death and long-term mortality. However, neither the time course of kidney function after percutaneous coronary intervention (PCI) nor the relation between the time course of kidney function and prognosis has been adequately studied. We studied 531 patients who underwent PCI for acute coronary syndrome. The continuous deterioration of kidney function (CDKF) was defined as a >25% increase in serum creatinine level or serum creatinine >0.5 mg/dl above baseline at 6 to 8 months after PCI. CDKF was observed in 87 patients (16.4%). Independent risk factors for CDKF were contrast-induced acute kidney injury, preprocedural hemoglobin level, and proteinuria. Patients with CDKF exhibited significant higher 5-year mortality rate than patients without CDKF (25% vs 9.4%, log-rank p = 0.0006). Independent risk factors for 5-year mortality were age >75 year, anemia, New York Heart Association class III or IV, low ejection fraction, and CDKF. CDKF is associated with an increased risk of all-cause mortality of 5 years in patients with acute coronary syndrome undergoing PCI.


Therapeutic Advances in Cardiovascular Disease | 2009

Aggressive statin therapy in multicenter and effectiveness for the reduction of intra-myocardial damage caused by non-ST elevation acute coronary syndrome: AMERICA study

Hidehiko Hara; Masato Nakamura; Itaru Yokouchi; Keiko Kimura; Naohiko Nemoto; Shingo Ito; Tsuyoshi Ono; Hideki Itaya; Masanori Shiba; Masamichi Wada; Raisuke Iijima; Masaya Yamamoto; Masato Yamamoto; Hisao Hara; Takuro Takagi; Toshiyuki Asahara; Kazuhisa Mitsuo; Nobuyuki Kobayashi; Kaoru Sugi

Background: While preprocedural statin treatment for acute coronary syndrome (ACS) is widely regarded as beneficial, there has been no prospective randomized multicenter trial of patients with non-ST elevation ACS in the Japanese population to examine the efficacy of preprocedural aggressive statin use. The aim of this study was to confirm this effect by prospective randomized multicenter design. Methods: Fifty patients who presented with non-ST elevation ACS were enrolled, and randomly assigned to aggressive statin administration before percutaneous coronary intervention (PCI). Troponin-T (TnT), creatine phosphokinase (CK), CK-myocardial band (CK-MB), high-sense C-reactive protein (hs-CRP), and brain natriuretic peptide (BNP) were measured at baseline and/ or after procedure. Results: Three days after PCI, the statin group had significantly less CK elevation compared with the nonstatin group (84±17 IU/l versus 180±68 IU/l, respectively, p = 0.02). CK-MB elevation also tended to be lower in the statin group than in the nonstatin group (3.2±1.9 versus. 7.0±3.0, respectively, p = 0.07), as was BNP level (3.2±1.9 versus 7.0±3.0 pg/ml, respectively, p = 0.07). The change of serum LDL cholesterol was significantly correlated with CK (p = 0.01) and TnT (p = 0.02) at 1 day after PCI. Conclusions: Aggressive statin usage before PCI to Japanese patients with non-ST elevation ACS appears to reduce myocardial damage after procedure. The degree of serum lipid level reduction may reflect the vulnerability of atheromatous plaques that could cause cardiac damage after PCI.


Cardiovascular Ultrasound | 2008

Distribution of ultrasonic radiofrequency signal amplitude detects lipids in atherosclerotic plaque of coronary arteries: an ex-vivo study

Hisao Hara; Taro Tsunoda; Naohiko Nemoto; Itaru Yokouchi; Masaya Yamamoto; Tsuyoshi Ono; Masao Moroi; Makoto Suzuki; Kaoru Sugi; Masato Nakamura

BackgroundAccumulation of lipids within coronary plaques is an important process in disease progression. However, gray-scale intravascular ultrasound images cannot detect plaque lipids effectively. Radiofrequency signal analysis could provide more accurate information on preclinical coronary plaques.MethodsWe analyzed 29 zones of mild atheroma in human coronary arteries acquired at autopsy. Two histologic groups, i.e., plaques with a lipid core (group L) and plaques without a lipid core (group N), were analyzed by automatic calculation of integrated backscatter. One hundred regions of interest were set on the target zone. Radiofrequency signals from a 50 MHz transducer were digitized at 240 MHz with 12-bit resolution. The intensity of integrated backscatter and its distribution within each plaque were compared between the two groups.ResultsAlthough the mean backscatter was similar between the groups, intraplaque variation of backscatter and backscatter in the axial direction were larger in group L than in group N (p = 0.02). Conventional intravascular ultrasound showed extremely low sensitivity for lipid detection, despite a high specificity. In contrast, a cut-off value>32 for the total variance of integrated backscatter identified lipid-containing plaque with a high sensitivity (85%) and specificity (75%).ConclusionCompared with conventional imaging, assessment of the intraplaque distribution of integrated backscatter is more effective for detecting lipid. As coronary atheroma progresses, its composition becomes heterogeneous and multi-layered. This radiofrequency technique can portray complex plaque histology and can detect the early stage of plaque progression.


Journal of Cardiology Cases | 2011

Bilateral spontaneous renal artery dissection

Tadashi Araki; Masato Nakamura; Takaaki Imamura; Makoto Utsunomiya; Maki Hori; Nobutaka Ikeda; Hideki Itaya; Kunihiko Makino; Naohiko Nemoto; Raisuke Iijima; Hidehiko Hara; Takuro Takagi; Kaoru Sugi

Spontaneous renal artery dissection is a rare condition that precedes renal infarction. We describe a 48-year-old, normotensive healthy woman presenting with left flank pain of sudden onset. Enhanced abdominal computed tomography demonstrated a dissecting intimal flap of the left renal artery complicating renal infarction. Doppler ultrasonography, selective angiography, and intravascular ultrasound revealed a dissecting intimal flap, with a large false lumen and narrow true lumen, of the renal artery bilaterally. Conservative management was undertaken with anticoagulant and analgesic therapy, and the patient was discharged after an uneventful clinical course.


International Journal of Cardiology | 2017

The right atrium and tricuspid annulus are cardinal structures in tricuspid regurgitation with or without pulmonary hypertension

Naohiko Nemoto; Jonathan G. Schwartz; John R. Lesser; Wesley Pedersen; Paul Sorajja; Ross Garberich; Erin M. Spinner; Robert S. Schwartz

BACKGROUND Right heart structural abnormalities occur in both tricuspid regurgitation (TR) and pulmonary hypertension (PH). They may occur independently or together, but their joint effects on cardiac structure are incompletely described. This study examined the interactions of TR severity and PH on right heart structural changes. METHODS The study evaluated 455 patients undergoing both echocardiography and CT angiography (CTA). Cases were divided into 3 groups by TR severity: trace (n=217), mild (n=174), and significant (moderate or severe, n=64). Each TR level was subdivided into two groups by PH absent or present. Cardiac structural measurements included tricuspid annulus area (TAA), right atrial (RA) and right ventricular volume (RV) indexed to body surface area. RESULTS Analysis by TR and PH showed that indexed RA Volume and TAA were very sensitive to TR severity. RA volume was most affected by pulmonary hypertension when TR was trace or mild, while PH had less effect on TAA. In significant TR, neither RA volume nor TAA were changed by PH. Indexed RV volume was insensitive to trace and mild TR, and PH similarly had little effect. CONCLUSIONS RA volume and tricuspid annulus area enlarge in proportion to TR severity, trace through significant. PH impacts RA volume but only in trace and mild TR. RA volume best reflects TR impact on right heart structure, both with and without PH. Right atrial volume and tricuspid annulus area are the cardinal indices of TR-induced right heart structural disease et al.l severities. ULTRAMINI ABSTRACT Right heart structural effects of TR and PH were examined in this study. Patients were evaluated by echo and CTA, and grouped by TR severity as trace, mild, and significant, and were subdivided by PH absence/presence. Analysis by TR severity and PH showed that Indexed RA volume is the parameter most sensitive to TR severity, and PH causes incremental RA volume increases in trace/mild TR. Indexed tricuspid annulus area (TAA) similarly increases with TR severity, but was unaffected by PH at any TR severity. RV volume is insensitive to TR severity and PH. Indexed right atrial volume and tricuspid annulus area are cardinal indices for TR-induced right heart structural disease and increase proportionally to TR severity. RA volume is more sensitive to PH than is tricuspid annular area. TR severity may be more accurately assessed by increased RA volume and annulus area. PERSPECTIVE STATEMENT The right atrium (RA) and tricuspid annulus (TA) are the cardinal cardiac structures affected by tricuspid regurgitation (TR). They each enlarge with TR severity. The right ventricle exhibits minimal change across TR severity. Pulmonary hypertension (PH) enhances TR-mediated RA and TA dilation, but only in trace and mild TR. PH has no effect on RA, TA, or RV size in significant TR. CENTRAL MESSAGE Right atrial volume and tricuspid annulus area are the most sensitive to TR severity, and are also sensitive to pulmonary hypertension.


Journal of the American College of Cardiology | 2016

TCT-376 The relationship between continuous deterioration of renal function in contrast induced acute kidney injury and long term outcome among patients with acute coronary syndrome. -Multicenter study-

Naohiko Nemoto; Hitoshi Anzai; Nobuyuki Kobayashi; Masato Nakamura

Washington Hospital Center, Falls Church, Virginia, United States; MedStar Washington Hospital Center, Washington, District of Columbia, United States; Washington Hospital Center, WHEATON, Maryland, United States; medstar washington hospital center, north bethesda, Maryland, United States; Washington Hospital Center, Washington, District of Columbia, United States; Washington Hospital Center, Washington, District of Columbia, United States; Washington Hospital Center, Washington, District of Columbia, United States; Washongton Hospital Center, Washington, District of Columbia, United States; Medstar Heart Institute, Washington, District of Columbia, United States


Journal of Clinical Cardiology | 2015

Relationship between Insulin Levels and Coronary Atherosclerosis in Newly Diagnosed Diabetes Mellitus and Impaired Glucose Tolerance

Naohiko Nemoto; Rintarou Nakajima; Kennji Ymazaki; Makoto Utsunomiya; Masaki Hori; Shingo Ito; Itaru Yokouchi; Masamichi Wada; Masanori Shiba; Hisao Hara; Hidehiko Hara; Takuro Takagi; Kaoru Sugi; Masato Nakamura

Background: While some therapies implemented for newly diagnosed Diabetes Mellitus (DM) or impaired Glucose Tolerance (IGT) are effective in preventing cardiovascular events, investigations of coronary plaque in patients with newly diagnosed DM or IGT are lacking. Methods: We evaluated 96 patients with acute coronary syndrome. The External Elastic Membrane (EEM), Lumen Cross-Sectional Area (CSA), plaque CSA, and plaque burden in the Left Anterior Descending (LAD) artery proximal to the lesion, diagnosed as normal by Coronary Angiography (CAG), were measured using Intravascular Ultrasound (IVUS). Patients were divided according to DM status (DM=35, non-DM=61). Non-DM patients underwent a 75g Oral Glucose Tolerance Test (OGTT) and were further divided into abnormal glucose tolerance (AGT; n=29) and Normal Glucose Tolerance (NGT) groups (n=32). Results: Quantitative Coronary Angiography (QCA) showed no significant differences in EEM or vessel diameter between groups. However, the lumen CSA was significantly smaller in the DM group than in the NGT group. The plaque CSA and plaque burden were significantly greater in the DM and AGT groups than in the NGT group. Total insulin and glucose values and insulin and glucose values at 120 min after the OGTT correlated with plaque CSA; insulin values at 120 min after the OGTT showed the strongest correlation (R=0.505, P<0.01). Conclusions: Coronary plaque was identified among newly diagnosed DM or IGT patients even when the CAG appeared normal, suggesting that preventive measures against atherosclerosis should be initiated prior to DM development.


Journal of the American College of Cardiology | 2011

COLOR CODED TISSUE CHARACTERIZATION BY 40 MHZ INTRAVASCULAR ULTRASOUND RELIABLY IDENTIFIES PLAQUE COMPOSITION COMPARISON WITH 64 SLICE COMPUTED TOMOGRAPHY

Makoto Utsunomiya; Masato Nakamura; Mami Nakanishi; Tadashi Araki; Masaki Hori; Nobutaka Ikeda; Kunihiko Makino; Hideki Itaya; Naohiko Nemoto; Raisuke Iijima; Hidehiko Hara; Takuro Takagi; Kaoru Sugi

Background: Identification of coronary plaque composition is important for selecting the treatment strategy, and 64-slice computed tomography (CT) is a noninvasive method of characterizing atherosclerotic plaques. However, the correlation between plaque characteristics detected by CT and intravascular ultrasound (IVUS) is not clear. A 40 MHz IVUS imaging system (iMap-IVUS) has recently been developed to evaluate plaque composition. The aim of this study was to compare iMap-IVUS with 64-slice CT angiography for the characterization of noncalcified coronary plaques.


Heart and Vessels | 2011

Higher body mass index at the time of acute myocardial infarction is associated with a favorable long-term prognosis (8-year follow-up)

Nobutaka Ikeda; Rintaro Nakajima; Makoto Utsunomiya; Masaki Hori; Hideki Itaya; Kunihiko Makino; Tsuyoshi Ono; Masaya Yamamoto; Naohiko Nemoto; Raisuke Iijima; Hidehiko Hara; Takuro Takagi; Hisao Hara; Masato Nakamura; Kaoru Sugi


Internal Medicine | 2011

Internal Jugular Thrombophlebitis Caused by Dermal Infection

Hisao Yoshikawa; Makoto Suzuki; Naohiko Nemoto; Hidehiko Hara; Go Hashimoto; Takenori Otsuka; Masao Moroi; Masato Nakamura; Kaoru Sugi

Collaboration


Dive into the Naohiko Nemoto's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge