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Search Results: 1 - 10 of 4576 matches for " Keiji Tanaka "
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Morbidity of Open Saphenous Vein Harvesting after Preoperative Ultrasonic Mapping  [PDF]
Susumu Isoda, Tamizo Kimura, Katsunori Tanaka, Kenji Nishimura, Nozomu Yamanaka, Shin-ichi Taguchi, Keiji Uchida, Norihisa Karube, Kiyotaka Imoto
Open Journal of Thoracic Surgery (OJTS) , 2015, DOI: 10.4236/ojts.2015.51002
Abstract: Preoperative echography of a saphenous vein graft (SVG) was studied. In 58 cases of consecutive coronary artery bypass grafting, 31 patients underwent SVG echography. Preoperative assessment revealed vein caliber, branching, or varicose saphenous veins. The location of the saphenous vein was marked. Saphenous veins were harvested by the open harvest technique, and the caliber of the veins and the availability of the anastomosis device were recorded. Postoperative morbidity was recorded. Preoperative findings revealed that four (6.5%) of 62 femoral saphenous veins were estimated as “not graftable” because of being a varicose vein or having a small caliber. Seven of 32 lower saphenous veins were estimated as “not graftable”. The mean discrepancy of the caliber was 0.6 mm undersized with preoperative estimation. During harvesting, one of 31 patients had a wrong marking. We were able to use all harvested veins. The morbidity of saphenous harvesting was observed in two (6.5%) of 31 patients. One patient whose marking was wrong had minor skin necrosis. Another patient experienced a hematoma because of the excess effect of warfarin. Preoperative ultrasonic mapping of the saphenous vein reduced useless harvesting, provided information concerning anastomosis device availability, and seemed to reduce morbidity because dissection can be minimal.
Fibrin Sealant Patch to Treat Dialysis-Associated Hemorrhagic Pericarditis  [PDF]
Susumu Isoda, Tamizo Kimura, Katsunori Tanaka, Kenji Nishimura, Nozomu Yamanaka, Shin-ichi Taguchi, Norihisa Karube, Keiji Uchida, Kiyotaka Imoto
Open Journal of Thoracic Surgery (OJTS) , 2015, DOI: 10.4236/ojts.2015.51001
Abstract: A 73-year-old male patient with a 3-year history of hemodialysis was admitted for the treatment of pericardial effusion. Echocardiography suggested a diagnosis of effusive pericarditis. Pericardiocentesis was performed several times. Six weeks after the admission, the patient developed cardiac tamponade. Surgical pericardiotomy showed the epicardium had a diffuse shaggy and hemorrhagic surface. To control diffuse oozing, fibrin sealant patches (Tachosil; CSL Behring, Tokyo, Japan) were attached to the epicardium. Oozing was then controlled.
Off-Pump Multilayered Sutureless Repair for a Left Ventricular Blowout Rupture after Aortic Dissection Repair  [PDF]
Susumu Isoda, Tamizo Kimura, Katsunori Tanaka, Kenji Nishimura, Nozomu Yamanaka, Shin-ichi Taguchi, Keiji Uchida, Norihisa Karube, Kiyotaka Imoto
Open Journal of Thoracic Surgery (OJTS) , 2015, DOI: 10.4236/ojts.2015.51003
Abstract: A left ventricular (LV) free wall rupture is a highly lethal condition. A 75-year-old female who experienced chest pain was diagnosed as having an acute aortic dissection Stanford type A and underwent emergent surgery. Under cardiopulmonary bypass with LV venting through the right superior pulmonary vein, a proximal aortic stamp was formed. The patient was cooled, selective antegrade brain perfusion was performed, and a hemiarch repair was performed. After the patient was transferred to the intensive care unit, her blood pressure suddenly fell to 50 mmHg. She had a blowout rupture in the left ventricular anterolateral free wall. Since the bleeding hall was not large and the damage to the surrounding left ventricular tissue was not very wide, an off-pump multilayered sutureless repair was performed by using three layers of collagen fleece squares with fibrinogen-based impregnation (TachoComb; CSL Behring, Tokyo, Japan) and three layers of gelatin-resorcin-formalin glue reinforced by an equine pericardial patch (Xenomedica; Edwards Lifesciences, LLC, Irvine, CA). The blow-out rupture seemed to be caused by perioperative myocardial infarction generated by the compression of the left ventricular vent to the LV lateral wall. The patient was free from re-rupture or aneurysm enlargement. The thickness of the hemostatic material seemed to help control the bulging of the aneurysm and to prevent further LV aneurysm enlargement and re-rupture.
Aggressive treatment with noninvasive ventilation for mild acute hypoxemic respiratory failure after cardiovascular surgery: Retrospective observational study
Keiko Nakazato, Shinhiro Takeda, Keiji Tanaka, Atsuhiro Sakamoto
Journal of Cardiothoracic Surgery , 2012, DOI: 10.1186/1749-8090-7-41
Abstract: We retrospectively analyzed all patients admitted to the intensive care unit after cardiovascular surgery, whose oxygenation transfer (PaO2/FIO2) deteriorated mildly after extubation, and in whom NIV was initiated. A two-way analysis of variance and the Bonferroni multiple comparisons procedure, the Mann–Whitney test, Fisher’s exact test or the χ2test was performed.A total of 94 patients with AHRF received NIV, of whom 89 patients (94%) successfully avoided endotracheal intubation (successful group) and five patients required reintubation (reintubation group). All patients, including the reintubated patients, were successfully weaned from mechanical ventilation and discharged from the intensive care unit. In the successful group, PaO2/FIO2 improved and the respiratory rate decreased significantly within 1?h after the start of NIV, and the improvement in PaO2/FIO2 remained during the whole NIV period.We conclude that NIV is beneficial for mild AHRF after cardiovascular surgery when it is started within 3?h after mild deterioration of PaO2/FIO2. We also think that it is important not to hesitate before performing reintubation when NIV is judged to be ineffective.
Odd-frequency Superconductivity on a Quasi-one-dimensional Triangular Lattice in the Hubbard Model
Keisuke Shigeta,Seiichiro Onari,Keiji Yada,Yukio Tanaka
Physics , 2008, DOI: 10.1103/PhysRevB.79.174507
Abstract: In order to clarify whether the odd-frequency superconductivity can be realized or not, we study a quasi-one-dimensional triangular lattice in the Hubbard model using the random phase approximation (RPA) and the fluctuation exchange (FLEX) approximation. We find that odd-frequency spin-singlet p-wave pairing can be enhanced on a quasi-one-dimensional isosceles triangular lattice.
Theory of tunneling spectroscopy for chiral topological superconductors
Akihiro Ii,Ai Yamakage,Keiji Yada,Masatoshi Sato,Yukio Tanaka
Physics , 2012, DOI: 10.1103/PhysRevB.86.174512
Abstract: We study the charge conductance of an interface between a normal metal and a superconducting quantum anomalous Hall system, based on the recursive Green's function. The angle resolved conductance gamma(ky, eV) with the momentum ky parallel to the interface and the bias voltage V shows a rich structure depending on the Chern number N of the system. We find that when the bias voltage is tuned to the energy dispersion of the edge mode, eV = Eedge(ky), the angle resolved conductance gamma(ky,Eedge(ky)) shows a pronounced even-odd effect; the conductance vanishes for N = 0 or 2 while it takes a universal value 2e^2/h for N = 1. In particular, in N = 2 phase, we find that the conductance gamma(ky,Eedge(ky)) becomes zero due to interference of two degenerate Majorana edge modes, although the corresponding surface spectral weight remains non-zero.
A Microscopic Theory of Odd-freqeuncy Pairing in the Two-dimensional Extended Hubbard Model
Keiji Yada,Seiichiro Onari,Yukio Tanaka,Kazumasa Miyake
Physics , 2008,
Abstract: We present a microscopic theory of fluctuation-mediated pairing mechanism in a two-dimensional extended Hubbard model. In contrast to conventional wisdom, odd-frequency spin-triplet pairing can be stabilized near the spin-density-wave critical point. Favorable conditions for the odd-frequency pairing are the presence of geometrical frustration and off-site Coulomb interaction.
Topology of Andreev Bound States with Flat Dispersion
Masatoshi Sato,Yukio Tanaka,Keiji Yada,Takehito Yokoyama
Physics , 2011, DOI: 10.1103/PhysRevB.83.224511
Abstract: A theory of dispersionless Andreev bound states on surfaces of time-reversal invariant unconventional superconductors is presented. The generalized criterion for the dispersionless Andreev bound state is derived from the bulk-edge correspondence, and the chiral spin structure of the dispersionless Andreev bound states is argued from which the Andreev bound state is stabilized. Then we summarize the criterion in a form of index theorems. The index theorems are proved in a general framework to certify the bulk-edge correspondence. As concrete examples, we discuss (i) dxy-wave superconductor (ii) px-wave superconductor, and (iii) noncentrosymmetric superconductors. In the last example, we find a peculiar time-reversal invariant Majorana fermion. The time-reversal invariant Majorana fermion shows an unusual response to the Zeeman magnetic field, which can be used to identify it experimentally.
Finite Size Effects of the Surface States in a Lattice Model of Topological Insulator
Kazuto Ebihara,Keiji Yada,Ai Yamakage,Yukio Tanaka
Physics , 2011, DOI: 10.1016/j.physe.2011.12.008
Abstract: Energy gap and wave function in thin films of topological insulator is studied, based on tight--binding model. It is revealed that thickness dependence of the magnitude of energy gap is composed of damping and oscillation. The damped behavior originates from the presence of gapless surface Dirac cone in the infinite thickness limit. On the other hand, the oscillatory behavior stems from electronic properties in the thin thickness limit.
Odd-frequency pair in topological superconductivity of 1D magnetic chain
Hiromi Ebisu,Keiji Yada,Hideaki Kasai,Yukio Tanaka
Physics , 2014, DOI: 10.1103/PhysRevB.91.054518
Abstract: A chain of magnetic atoms with non-collinear spin configuration on a superconductor is a promising new system that can host Majorana Fermions (MFs). In this study, we clarify that in the presence of MFs, an odd-frequency Cooper pair is generated at the edge of the chain. Furthermore, it is revealed that this feature is robust against the distance between magnetic atoms. We also elucidate the close relationship between the pair amplitude of the odd-frequency pair, the parity of the wave function, and the direction of the MF spin. If Rashba-type spin-orbit coupling is included, MFs can be realized even in a collinear alignment of magnetic atoms, $i.e.$, in a ferromagnetic or anti-ferromagnetic chain on a superconductor. Then, the odd-frequency pairing is generated at the edge, similar to the non-collinear case. Based on our results, it can be concluded that the detection of the zero energy peak of the local density of states by scanning tunneling microscopy at the edge of the magnetic chain is strong evidence for the generation of odd-frequency pairing.
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