Gen Shinohara

The Jikei University School of Medicine, Tokyo, Tokyo-to, Japan

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Publications (11)13.96 Total impact

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    ABSTRACT: A patient with multiple leaks caused by active mitral prosthetic valve endocarditis with an annular abscess underwent repeat mitral valve replacement. To secure the new mitral prosthesis, sutures were placed through the healthy interatrial septal wall from right to left at the posteromedial region and then to the new prosthetic valve sewing cuff. In the anterolateral region, sutures were placed through the reconstructed annulus after debridement of the abscess and then reinforced with a pericardial xenograft patch. Postoperatively, the perivalvular leakage stopped and the patient recovered uneventfully.
    General Thoracic and Cardiovascular Surgery 06/2012;
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    ABSTRACT: The benefit of terminal blood cardioplegia (TWBCP) is insufficient after prolonged ischemia associated with inevitable oxidant-mediated injury by this modality alone. We tested the effects of TWBCP supplemented with high-dose olprinone, which is a phosphodiesterase III inhibitor, a clinically available compound with the potential to reduce oxidant stress and calcium overload. We evaluated the effects with respect to avoiding oxidant-mediated myocardial reperfusion injury and prompt functional recovery after prolonged single-dose crystalloid cardioplegic arrest in a infantile piglet cardiopulmonary bypass (CPB) model. Fifteen piglets were subjected to 90 min of cardioplegic arrest on CPB, followed by 30 min of reperfusion. In group I, uncontrolled reperfusion was applied without receiving TWBCP; in group II, TWBCP was given; in group III, TWBCP was supplemented with olprinone (3 μg/ml). Myocardial performance was evaluated before and after CPB by a left ventricular (LV) function curve and pressure-volume loop analyses. Biochemical injury was determined by measurements of troponin-T and lipid peroxide (LPO) in coronary sinus blood. Group III showed significant LV performance recovery (group I, 26.5% ± 5.1%; group II, 42.9% ± 10.8%; group III, 81.9% ± 24.5%, P < 0.01 vs. groups I and II), associated with significant reduction of troponin-T and LPO at the reperfusion phase. No piglets in group III needed electrical cardioversion. We concluded that TWBCP with olprinone reduces myocardial reperfusion injury by reducing oxidant-mediated lipid peroxidation, and it accelerates prompt and persistent LV functional recovery with suppression of reperfusion arrhythmia.
    General Thoracic and Cardiovascular Surgery 02/2012; 60(2):73-81.
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    ABSTRACT: An in vivo study of piglets on cardiopulmonary bypass was performed to determine whether postconditioning has a cardioprotective effect after cardioplegic arrest in large animals. Eighteen piglets were subjected to 90 minutes of cardioplegic arrest followed by 30 minutes of reperfusion. In 6 animals (control), there was no intervention at reperfusion. In 6 other animals, 6 cycles of unclamping and reclamping for 10 seconds each were done before reperfusion (postconditioning 10), whereas 3 cycles of unclamping and reclamping for 30 seconds each were performed in another 6 piglets (postconditioning 30). Recovery of left ventricular contractility and diastolic function (percent of preischemic value) was significantly better in both postconditioning groups (contractility: 89.2% and 118.2; diastolic function: 142.3% and 120.4; in the postconditioning 10 and 30 groups, respectively) compared with the control (contractility: 46.1%; diastolic function: 218.5%). Recovery of global cardiac function (ventricular function curve analysis) was improved only in the postconditioning 30 group. Troponin-T release during reperfusion was significantly reduced in the postconditioning 10 group compared with all groups (plasma troponin-T was 0.58 ng/mL in postconditioning 10, 1.85 in postconditioning 30, and 2.54 in control). The myocardial lipid peroxide was significantly higher in the control group than in both postconditioning groups after reperfusion (199% vs 112% and 131%). Both postconditioning algorisms promoted functional recovery after cardioplegic arrest in a large animal model along with the limitation of lipid peroxidation with or without the reduction of troponin-T release.
    The Journal of thoracic and cardiovascular surgery 02/2011; 142(4):926-32. · 3.41 Impact Factor
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    ABSTRACT: First-stage palliation of hypoplastic left heart syndrome has been revolutionized by the recent introduction of a right ventricle-to-pulmonary artery (RV-PA) conduit as an alternative to a systemic-to-pulmonary shunt. However, most conduits are unvalved, and the use of valved xenografts was abandoned during the early era of this operation. We performed a successful modified Norwood operation in a 2-month-old infant with aortic atresia and ventricular and atrial septal defects using a hand-made down-sizing valved graft as an RV-PA conduit. The postoperative course was uneventful with well-balanced pulmonary and arterial perfusion. We believe that minimization of the regurgitant volume from an unvalved prosthetic conduit by utilizing this modification might be of benefit in this particular group of patients.
    General Thoracic and Cardiovascular Surgery 01/2011; 59(1):30-3.
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    ABSTRACT: A 5-month-old boy was presented for surgical repair of scimitar syndrome associated with right lung hyperplasia, severe pulmonary hypertension, ventricular septal defect (VSD), and atrial septal defect. The calculated shunt fraction (Qp/Qs) was 3.1:1.0, pulmonary vascular resistance was 4.6, and the perfusion lung scan showed a marked decrease (11%) in right pulmonary blood flow. Surgical repair was performed through the right fourth intercostal space with the patient supine. The anomalous vein was divided and interposed with a short azygos vein graft, followed by closure of the VSD. Finally, the interposed azygos vein was anastomosed to the left atrium. Although pulmonary artery pressure was normalized at the 2-year follow-up, cardiac catheterization 6 months after the operation demonstrated right pulmonary vein obstruction.
    General Thoracic and Cardiovascular Surgery 10/2010; 58(10):524-7.
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    ABSTRACT: Pulmonary ischemia and reperfusion during routine open heart surgery with cardiopulmonary bypass can lead to pulmonary dysfunction and vasoconstriction, resulting in a high morbidity and mortality. We investigated whether ischemia/reperfusion-induced pulmonary dysfunction after full-flow cardiopulmonary bypass could be prevented by the infusion of leukocyte-depleted hypoxemic blood during the early phase of reperfusion (terminal leukocyte-depleted lung reperfusion) and whether the benefits of this method were nullified by using hyperoxemic blood for reperfusion. Twenty-one neonatal piglets underwent 180 minutes of full-flow cardiopulmonary bypass with pulmonary artery occlusion, followed by reperfusion. The piglets were divided into 3 groups of 7 animals. In group I, uncontrolled reperfusion was achieved by unclamping the pulmonary artery. In contrast, pulmonary reperfusion was done with leukocyte-depleted hyperoxemic blood in group II or with leukocyte-depleted hypoxemic blood in group III for 15 minutes at a flow rate of 10 mL/min/kg before pulmonary artery unclamping. Then the animals were monitored for 120 minutes to evaluate post-cardiopulmonary bypass pulmonary function. Group I developed pulmonary dysfunction that was characterized by an increased alveolar-arterial oxygen difference (204 + or - 57.7 mm Hg), pulmonary vasoconstriction, and decreased static lung compliance. Terminal leukocyte-depleted lung reperfusion attenuated post-cardiopulmonary bypass pulmonary dysfunction and vasoconstriction when hypoxemic blood was used for reperfusion (alveolar-arterial oxygen difference, 162 + or - 61.0 mm Hg). In contrast, no benefit of terminal leukocyte-depleted lung reperfusion was detected after reperfusion with hyperoxemic blood (alveolar-arterial oxygen difference, 207 + or - 60.8 mm Hg). Reperfusion with leukocyte-depleted hypoxemic blood has a protective effect against ischemia/reperfusion-induced pulmonary dysfunction by reducing endothelial damage, cytokine release, and leukocyte activation.
    The Journal of thoracic and cardiovascular surgery 11/2009; 139(1):174-80. · 3.41 Impact Factor
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    ABSTRACT: Phosphodiesterase (PDE) III inhibitors have been reported in various cellular protective activities via the cyclic adenosine monophosphate (cAMP) pathway. We investigated the effects of amrinone on ischemia/reperfusion injury and intracellular calcium (Ca2+) handling if utilized as a component of terminal warm blood cardioplegia (TWBCP). Anesthetized pig hearts were subjected to 90-min global ischemia with single-dose crystalloid cardioplegia, followed by 30-min reperfusion under cardiopulmonary bypass. The animals were divided into three groups according to the contents of TWBCP (n = 5 each): Control, no TWBCP; TWBCP, no additive; Amrinone, TWBCP with amrinone. The time course of cardiac function and biochemical samples were measured. Further, coronary perfusion and ventricular arrhythmia were evaluated during reperfusion. Cardiac function improved with amrinone. Specifically, the amrinone group showed an increase of myocardial cAMP (p <0.05) and a suppression of creatine kinase, troponin-T, and lipid peroxide after reperfusion (p <0.05); many cases also showed much improvement of coronary perfusion and spontaneous resuscitation after global ischemia. Ischemia and/or reperfusion deplete myocardial cAMP, leading to impaired Ca2+ handling and further to cardiac dysfunction. High-dose PDEIII inhibitor in TWBCP may replenish myocardial cAMP and promote rapid and sustained cardiac functional recovery with various cellular protective effects after open-heart surgery.
    Annals of thoracic and cardiovascular surgery : official journal of the Association of Thoracic and Cardiovascular Surgeons of Asia. 10/2009; 15(5):311-7.
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    ABSTRACT: This study was performed to identify risk factors for hospital death in patients with acute and active infective endocarditis (AAIE) after surgical intervention. From 1980 to 2004, 94 patients underwent surgery for AAIE (age range, 3-77 years; 76% males). Congestive heart failure (CHF) was present in 44 patients, as well as vegetations in 64, septicemia in 16, abscesses in 17, and emboli in 22; 16 patients had prosthetic valve endocarditis. Streptococci were the most common bacteria (34 patients), followed by staphylococci (17 patients). Mechanical valves were selected for 73 patients and bioprosthetic valves for 16. Mitral valve plasty was performed in 4 patients. Aortic root or aorto-mitral discontinuity was repaired in 17 patients, including Manouguian's double valve replacement in 6 and aortic root replacement in 4. Overall hospital mortality was 15% (14 patients). Univariate analysis identified CHF (p=0.016), abscess (p=0.014), and prosthetic valve endocarditis (p=0.043) as risk factors. However, multivariate analysis only identified CHF (p=0.019) as an independent risk factor. In AAIE, early surgical intervention is advisable before the occurrence of complications such as root abscess and CHF, particularly before the onset of CHF.
    Circulation Journal 01/2009; 72(12):2062-8. · 3.69 Impact Factor
  • Japanese Journal of Cardiovascular Surgery. 01/2009; 38(2):156-159.
  • Gen Shinohara, Kazuaki Shiratori
    Japanese Journal of Cardiovascular Surgery. 01/2006; 35(5):299-303.
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    ABSTRACT: The procedure of quadrangular resection and suture for prolapsed posterior leaflet of the mitral valve is a reliable and reproducible method that achieves excellent long-term results. However, triangular resection and suture of a prolapsed anterior leaflet is not widely supported and different techniques have been advocated. The aim of this study was to review our experience of mitral valve repair in which resection of the anterior and/or posterior leaflets was performed. Between October 1991 and September 2003, 105 patients with mitral regurgitation underwent mitral valve reconstruction with leaflet resection, including 55 patients with quadrangular resection of the posterior leaflet (P), 32 patients with triangular resection of the anterior leaflet (A), and 18 patients with resection of both leaflets (A+P). The mean follow-up period was 63.6 (1 to 139) months. Reoperation was required in 2 patients, each after resection of the anterior or posterior leaflet. The freedom from reoperation rates at 10 years in 93% +/- 5% of patients after triangular resection of the anterior leaflet, 96% +/- 3% after quadrangular resection of the posterior leaflet, and 100% after resection of both leaflets. There were no significant differences of survival or risk of reoperation among these three groups. The postoperative mitral valve area was significantly smaller than the preoperative area in all three groups, but remained large enough (A: 2.84 +/- 1.07; P: 2.6 +/- 0.87; A+P: 3.09 +/- 1.20 cm2) for adequate valve function. Triangular resection of a prolapsed anterior mitral leaflet is a reliable, reproducible, and durable procedure, like quadrangular resection of a prolapsed posterior leaflet.
    The Annals of thoracic surgery 03/2005; 79(2):475-9. · 3.45 Impact Factor