Yuji Miyamoto

Hyogo College of Medicine, Nishinomiya, Hyōgo, Japan

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Publications (128)300.25 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: An 81-year-old woman developed severe hemolytic anemia after aortic valve replacement. The anemia was not caused by paravalvular leakage, as in most cases. Instead, it occurred secondary to left ventricular outflow tract obstruction that had not been seen preoperatively and was induced by afterload reduction following aortic valve replacement. The hemolytic anemia was drug-refractory and finally treated with dual-chamber pacing, as for hypertrophic cardiomyopathy.
    General Thoracic and Cardiovascular Surgery 09/2015; DOI:10.1007/s11748-015-0586-z
  • International journal of cardiology 06/2015; 195:281-282. DOI:10.1016/j.ijcard.2015.05.177 · 4.04 Impact Factor
  • Journal of Vascular Surgery 06/2015; 61(6):170S. DOI:10.1016/j.jvs.2015.04.323 · 3.02 Impact Factor
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    ABSTRACT: Although iron is an essential element for maintaining physiological function, excess iron leads to tissue damage caused by oxidative stress and inflammation. Oxidative stress and inflammation play critical roles for the development of abdominal aortic aneurysm (AAA). However, it has not been investigated whether iron plays a role in AAA formation through oxidative stress and inflammation. We, therefore, examined whether iron is involved in the pathophysiology of AAA formation using human AAA walls and murine AAA models. Human aortic walls were collected from 53 patients who underwent cardiovascular surgery (non-AAA=34; AAA=19). Murine AAA was induced by infusion of angiotensin II to apolipoprotein E knockout mice. Iron was accumulated in human and murine AAA walls compared with non-AAA walls. Immunohistochemistry showed that both 8-hydroxy-2'-deoxyguanosine and CD68-positive areas were increased in AAA walls compared with non-AAA walls. The extent of iron accumulated area positively correlated with that of 8-hydroxy-2'-deoxyguanosine expression area and macrophage infiltration area in human and murine AAA walls. We next investigated the effects of dietary iron restriction on AAA formation in mice. Iron restriction reduced the incidence of AAA formation with attenuation of oxidative stress and inflammation. Aortic expression of transferrin receptor 1, intracellular iron transport protein, was increased in human and murine AAA walls, and transferrin receptor 1-positive area was similar to areas where iron accumulated and F4/80 were positive. Iron is involved in the pathophysiology of AAA formation with oxidative stress and inflammation. Dietary iron restriction could be a new therapeutic strategy for AAA progression. © 2015 American Heart Association, Inc.
    Arteriosclerosis Thrombosis and Vascular Biology 04/2015; 35(6). DOI:10.1161/ATVBAHA.115.305586 · 6.00 Impact Factor
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    ABSTRACT: Left atrial (LA) dimension can predict atrial fibrillation (AF) recurrence after catheter-based or surgical ablation. Pulmonary vein isolation (PVI) may be a surgical option during aortic valve replacement (AVR) and/or coronary artery bypass grafting (CABG), though consensus regarding patient selection and late outcome is lacking. We studied 160 patients (mean age 70 ± 9 years) with paroxysmal AF who underwent radiofrequency-based PVI during AVR and/or CABG, and were followed up postoperatively for at least 6 months. Mean preoperative LA dimension was 44 ± 7 mm. Serial echocardiography was performed to evaluate left ventricular (LV) and LA dimensions, E/e', estimated systolic pulmonary artery (PA) pressure and degree of valvular regurgitation. Follow-up was completed with a mean duration of 47 ± 25 months. At the latest follow-up, 133 patients (83%) remained in sinus rhythm. Preoperative LA dimension was independently associated with increased risk of AF recurrence at 6 months after surgery [adjusted odds ratio 1.3 per 1-mm increase in LA dimension, 95% confidence interval (CI) 1.1-1.6, P < 0.001]. Receiver-operating characteristic curve analysis demonstrated an optimal cut-off value for preoperative LA dimension of 45 mm to predict sinus rhythm restoration (98% for <45 mm vs 55% for ≥45 mm, P < 0.001). Patients with LA dimension ≥45 mm had a significantly lower 5-year survival rate (62 ± 7 vs 82 ± 7%, P = 0.025) and freedom from adverse events defined as cerebral infarction/haemorrhage, admission for heart failure, catheter ablation and permanent pacemaker implantation (58 ± 7 vs 91 ± 4%, P < 0.001). Multivariate analysis showed that preoperative LA dimension ≥45 mm was independently associated with adverse events (adjusted hazards ratio 2.4, 95% CI 1.2-5.1, P = 0.019). Serial echocardiography demonstrated improvement in LV systolic function irrespective of LA dimension, whereas patients with LA dimension ≥45 mm showed less improvement in LA dimension and systolic PA pressure (interaction effect P < 0.001) and persistent higher E/e' (group effect P < 0.001), along with aggravated tricuspid regurgitation. In patients with paroxysmal AF related to aortic valve disease and/or coronary artery disease, a dilated left atrium (≥45 mm) was associated with inferior AF- and event-free survival after PVI, accompanied by persistent abnormalities in cardiac and haemodynamic function. These findings may assist patient selection for PVI during AVR and/or CABG. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
    European journal of cardio-thoracic surgery: official journal of the European Association for Cardio-thoracic Surgery 01/2015; DOI:10.1093/ejcts/ezu532 · 3.30 Impact Factor
  • 01/2015; 44(4):241-244. DOI:10.4326/jjcvs.44.241
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    ABSTRACT: We treated a 57-year-old female patient with an atrial tumor that was widely attached to the atrial septum. The tumor was diagnosed as a cystic tumor of the atrioventricular node (CTAVN). This type of tumor is rare, and its antemortem diagnosis is difficult because it is usually asymptomatic. This tumor may cause sudden death; thus surgical resection is recommended. We performed partial resection instead of total resection to avoid pacemaker implantation. Copyright © 2014 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.
    The Annals of Thoracic Surgery 12/2014; 98(6):2223-6. DOI:10.1016/j.athoracsur.2014.02.061 · 3.85 Impact Factor
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    ABSTRACT: The purpose of this study was to evaluate whether edaravone (Radicut(®), Mitsubishi Tanabe Pharma Co., Osaka, Japan) injected at the start of reperfusion can suppress myonephropathic-metabolic syndrome (MNMS). MNMS models were made by clamping the bilateral common femoral arteries for 5 hours. At de-clamping (at the start of reperfusion), they were intra-peritoneal injected with 9.0 mg/kg of edaravone (the edaravone group, n = 5) or an equal volume of saline (the control group, n = 5). At five hours after de-clamping, the lower extremity muscles were stained with hematoxylin & eosin (H&E) to count the viable cells, and periodic acid- Schiff (PAS) to assess the glycogen storage. The lungs were also stained with H&E to expresse the alveolar wall thickness, and naphthol AS-D chloroacetate esterase to label infiltrating active neutrophils. The viable muscle cells in the edaravone group was significantly greater than that of the control group (593 ± 60 vs. 258 ± 31 cells/mm(2), p < 0.01). The PAS-positive area in the edaravone group was also significantly higher than that in the control group (30.1 ± 6.9 vs. 7.3 ± 2.1%, p < 0.001). The alveolar wall thickness in the edaravone group was significantly lower than that in the control group (63.6 ± 5.6 vs. 17.2 ± 5.2%, p < 0.001). The active neutrophil infiltration in the edaravone group was also significantly lower than that in the control group (249 ± 59 vs. 68 ± 8 cells/mm(2), p < 0.001). We conclude that edaravone injected at the start of reperfusion can suppress not only muscle reperfusion injury but also lung damage.
    International Journal of Angiology 09/2014; 23(3):193-6. DOI:10.1055/s-0034-1387825
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    ABSTRACT: Valvular calcification is a prominent feature of aortic valve stenosis (AS), and calcified aortic valves share several features with bone tissue. Hypoxia-inducible factor-2 (HIF-2) is activated by nuclear factor-κB (NF-κB) and plays a critical role in an osteoblastic differentiation. The study aim was to determine whether the NF-κB-HIF-2 pathway is involved in the pathophysiology of calcified aortic valve disease. A total of 50 specimens of aortic valve leaflets obtained from patients who had undergone aortic valve replacement for AS was examined. The aortic valve leaflets from 10 patients with annulo-aortic ectasia (AAE) served as controls. The stenotic valve leaflets were examined using immunohistochemistry to detect NF-κB, HIF-2α, vascular endothelial growth factor (VEGF), vascular endothelial cells, and collagen X. The calcification area was measured and any correlation between the calcification area and NF-κB-HIF-2 pathway was assessed. NF-κB and HIF-2α were expressed in the leaflets from patients with AS, but not in those from AAE controls. Both factors were expressed around massive calcified lesions, and HIF-2α was co-localized with NF-κB. VEGF, neoangiogenesis and collagen X were located in the area where HIF-2α was expressed, and correlated positively with HIF-2α expression. The calcification area correlated positively with collagen X expression. The NF-κB-HIF-2 pathway was expressed in calcified aortic valves and associated with an increased expression of VEGF and collagen X. This signaling pathway may play important roles in the pathophysiology of AS.
    The Journal of heart valve disease 09/2014; 23(5):558-66. · 0.75 Impact Factor
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    Journal of the American College of Cardiology 04/2014; 63(12):A2109. DOI:10.1016/S0735-1097(14)62112-4 · 16.50 Impact Factor
  • 01/2014; 43(3):158-161. DOI:10.4326/jjcvs.43.158
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    ABSTRACT: It is well known that free radicals cause reperfusion injury following leg ischemia. We showed that the free radical scavenger, edaravone (Radicut, Mitsubishi Tanabe Pharma Co., Osaka, Japan), might suppress reperfusion injury in rat. In this study, we used transmission electron microscope (TEM) to investigate how edaravone suppresses reperfusion injury by focusing on glycogen granules in the lower extremity muscles. Male Lewis rats (582 ± 35 g) were intraperitoneally injected with edaravone (3.0 mg/kg, edaravone group, n = 5) or the same dose of saline (control group, n = 5). The rat reperfusion injury models were induced by clamping the bilateral common femoral arteries for 5 hours and then declamping. The muscles were harvested at 5 hours after the start of reperfusion. Under a TEM (JEM-1220, Nippon Denshi Co., Tokyo, Japan), we counted the number of glycogen granules at ×50,000 magnification on each five different fields. The TEM sections from the control group showed a marked loss of glycogen granules and swollen mitochondria. In contrast, the TEM sections from the edaravone group showed numerous glycogen granules and normal mitochondria. The mean density of glycogen granules in the edaravone group was significantly higher than that in the control group (88.5 ± 5.3 vs. 16.4 ± 3.1 particles/µm(2), p < 0.001). Our TEM results confirmed that edaravone suppresses reperfusion injury following leg ischemia by maintaining the glycogen granules in muscles.
    International Journal of Angiology 12/2013; 22(4):267-70. DOI:10.1055/s-0033-1357261
  • Shinya Fukui · Yuji Miyamoto
    Kyobu geka. The Japanese journal of thoracic surgery 12/2013; 66(13):1175-7.
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    ABSTRACT: Various rings are available to achieve more physiologic mitral valve repair from viewpoints of physiologic mitral annular structure or dynamics. We evaluated preoperative and postoperative mitral annular structures and dynamics. Thirty-six patients underwent mitral valve repair for degenerative mitral insufficiency. Carpentier-Edwards Physio II ring (semirigid [Edwards Lifesciences, Irvine, CA]), St. Jude Medical Rigid Saddle Ring (RSR [St. Jude Medical, St. Paul, MN]), and MEMO 3D ring (semirigid [Sorin SpA, Milan, Italy]) were implanted in 13, 12, and 11 patients, respectively. Intraoperative real-time three-dimensional transesophageal echocardiography was performed before and after repair. The postoperative anteroposterior diameter reduction rate from end diastole to end systole was significantly (p < 0.0001) larger in MEMO (9.58% ± 2.91%) than in Physio II (0.98% ± 1.04%) and RSR (1.94% ± 1.95%). There were no significant differences in the commissure-to-commissure diameter reduction rates among the groups: 0.81% ± 1.98% for Physio II, 0.12% ± 0.53% for RSR, and 0.51% ± 1.98% for MEMO. The postoperative end-systolic annular height commissure width ratio was significantly (p < 0.0001) larger in both Physio II (17.9% ± 3.0%) and RSR (18.5% ± 1.6%) than in MEMO (13.6% ± 3.0%). The postoperative annular height commissure width ratio increase rate from end diastole to end systole was significantly larger in MEMO (5.1% ± 2.3%) than in Physio II (0.1% ± 0.6%) and RSR (0.3% ± 0.5%). Physio II and RSR could restore the physiologic three-dimensional annular shape, but the annular motion was diminished. Conversely, MEMO could preserve both the anteroposterior movement and folding dynamics, but no three-dimensional restoration of the mitral annulus was obtained.
    The Annals of thoracic surgery 11/2013; 97(2). DOI:10.1016/j.athoracsur.2013.09.077 · 3.85 Impact Factor
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    ABSTRACT: We treated a 21-year-old man with right ventricular thrombus caused by nephrotic syndrome. The right ventricular thrombus was safely removed and his postoperative course was uneventful. Peri- and postoperative management after surgery for the worsened nephrotic syndrome was relatively unique and difficult, and critical care was essential for saving the patient's life and protecting renal function.
    General Thoracic and Cardiovascular Surgery 10/2013; 63(9). DOI:10.1007/s11748-013-0314-5
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    ABSTRACT: Aim: to evaluate the strategy for open heart surgery after renal transplantation performed in a single institution in Japan. Methods: we reviewed 6 open heart surgeries after renal transplantation in 5 patients, performed between January 1992 and December 2012. The patients were 3 men and 2 women with a mean age of 60 ± 11 years (range 46-68 years). They had old myocardial infarction and unstable angina, aortic and mitral stenosis, left arterial myxoma, aortic stenosis, and native valve endocarditis followed by prosthetic valve endocarditis. Operative procedures included coronary artery bypass grafting, double-valve replacement, resection of left arterial myxoma, 2 aortic valve replacements, and a double-valve replacement. Renal protection consisted of steroid cover (hydrocortisone 100-500 mg or methylprednisolone 1000 mg) and intravenous immunosuppressant infusion (cyclosporine 30-40 mg day(-1) or tacrolimus 1.0 mg day(-1)). Results: 5 cases were uneventful and good renal graft function was maintained at discharge (serum creatinine 2.1 ± 0.5 mg dL(-1)). There was one operative death after emergency double-valve replacement for methicillin-resistant Staphylococcus aureus-associated prosthetic valve endocarditis. Although the endocarditis improved after valve replacement, the patient died of postoperative pneumonia on postoperative day 45. Conclusions: careful perioperative management can allow successful open heart surgery after renal transplantation. However, severe complications, especially methicillin-resistant Staphylococcus aureus infection, may cause renal graft loss.
    Asian cardiovascular & thoracic annals 10/2013; 22(7). DOI:10.1177/0218492313507784
  • Yuji Miyamoto
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    ABSTRACT: The original elephant trunk technique was developed by Borst in 1983 for the treatment of aortic arch aneurysms. This technique reduced operative risks, but was associated with cumulative mortality rates of 6.9 % for the first stage and 7.5 % for the second stage. Patients also waited a long time between two major surgical procedures. Only 50.4 % of patients underwent the second-stage surgery, and there was a significant interval mortality rate of 10.7 %. With the advent of stent-graft techniques, two different hybrid elephant trunk techniques were developed. One technique is first-stage elephant trunk graft placement followed by second-stage endovascular completion. The conventional elephant trunk graft provides a good landing zone for the stent-graft, and endovascular completion is a useful alternative to conventional second-stage surgery. This method has few major complications, and a postoperative paraplegia rate of 1.1 %. The other technique is the frozen elephant trunk technique. This technique eliminates the need for subsequent endovascular completion, and is particularly useful for the treatment of acute type A dissection because it can achieve a secure seal. However, it is associated with a higher rate of spinal cord ischemia than other methods such as the original elephant trunk technique. The left subclavian artery (LSA) is often lost when performing a hybrid elephant trunk procedure. Revascularization of the LSA should be performed to prevent arm ischemia and neurological complications such as paraplegia or stroke, although the level of evidence for this recommendation is low.
    General Thoracic and Cardiovascular Surgery 08/2013; 62(3). DOI:10.1007/s11748-013-0299-0
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    Journal of the American College of Cardiology 03/2013; 61(10):E309. DOI:10.1016/S0735-1097(13)60309-5 · 16.50 Impact Factor
  • International journal of cardiology 01/2013; 168(1). DOI:10.1016/j.ijcard.2012.12.059 · 4.04 Impact Factor
  • 01/2013; 42(2):89-93. DOI:10.4326/jjcvs.42.89

Publication Stats

489 Citations
300.25 Total Impact Points


  • 2005–2015
    • Hyogo College of Medicine
      • Department of Cardiovascular Surgery
      Nishinomiya, Hyōgo, Japan
  • 2002–2006
    • Osaka City University
      • Department of Cardiovascular Surgery
      Ōsaka, Ōsaka, Japan
  • 1997–2006
    • Sakurabashi Watanabe Hospital
      Ōsaka, Ōsaka, Japan
  • 2004
    • Osaka University
      • Department of Surgery
      Suika, Ōsaka, Japan
  • 1996
    • Yao Municipal Hospital
      Yaochō, Ōsaka, Japan
  • 1995
    • Texas Heart Institute
      Houston, Texas, United States