Takashi Kido

The administration of high-mobility group box 1 fragment prevents deterioration of cardiac performance by enhancement of bone marrow mesenchymal stem cell homing in the delta-sarcoglycan-deficient hamster

Objectives We hypothesized that systemic administration of high-mobility group box 1 fragment attenuates the progression of myocardial fibrosis and cardiac dysfunction in a hamster model of dilated cardiomyopathy by recruiting bone marrow mesenchymal stem cells thus causing enhancement of a self-regeneration system. Methods Twenty-week-old J2N-k hamsters, which are δ-sarcoglycan-deficient, were treated with systemic injection of high-mobility group box 1 fragment (HMGB1, n=15) or phosphate buffered saline (control, n=11). Echocardiography for left ventricular function, cardiac histology, and molecular biology were analyzed. The life-prolonging effect was assessed separately using the HMGB1 and control groups, in addition to a monthly HMGB1 group which received monthly systemic injections of high-mobility group box 1 fragment, 3 times (HMGB1, n=11, control, n=9, monthly HMGB1, n=9). Results The HMGB1 group showed improved left ventricular ejection fraction, reduced myocardial fibrosis, and increased capillary density. The number of platelet-derived growth factor receptor-alpha and CD106 positive mesenchymal stem cells detected in the myocardium was significantly increased, and intra-myocardial expression of tumor necrosis factor α stimulating gene 6, hepatic growth factor, and vascular endothelial growth factor were significantly upregulated after high-mobility group box 1 fragment administration. Improved survival was observed in the monthly HMGB1 group compared with the control group. Conclusions Systemic high-mobility group box 1 fragment administration attenuates the progression of left ventricular remodeling in a hamster model of dilated cardiomyopathy by enhanced homing of bone marrow mesenchymal stem cells into damaged myocardium, suggesting that high-mobility group box 1 fragment could be a new treatment for dilated cardiomyopathy.

Impact of Hybrid Stage 1 Palliation for Hypoplastic Left Heart Syndrome: Histopathological Findings

The purpose of the study is to analyze the impact of hybrid stage 1 palliation on right ventricular myocardial pathology in hypoplastic left heart syndrome. Sufficient amount of right ventricular biopsies could be obtained from 16 of 32 patients who underwent Norwood operation between 2007 and 2013. Histopathological findings of right ventricle in patients who underwent primary Norwood operation (primary group, n = 5), patients with aortic atresia (HS1P AA group, n = 6) or aortic stenosis (HS1P AS group, n = 5) who underwent staged Norwood palliation following hybrid stage 1 palliation were compared. To eliminate the influence of right ventricular pressure afterload, right ventricular biopsies were obtained from patients with truncus arteriosus communis (TAC group, n = 6) at total correction. The percentage of myocardial fibrosis was significantly higher in both HS1P groups than in TAC group; moreover, it was significantly higher in HS1P AA group than in primary group. Capillary vascular density was significantly lower in all hypoplastic left heart syndrome groups than in TAC group. At the sub-endocardial layer, collagen type I/III ratios were higher in HS1P AA group than in other hypoplastic left heart syndrome groups. The proportions of N-cadherin immunolocalized to myocyte termini were lower in all hypoplastic left heart syndrome groups than in TAC group. Right ventricle in hypoplastic left heart syndrome showed more significant ischemic change and myocardial immaturity than that in truncus arteriosus communis. Hybrid stage 1 palliation for aortic atresia would be a risk factor for further right ventricular myocardial ischemia.

Clinical Predictors of Right Ventricular Myocardial Fibrosis in Patients With Repaired Tetralogy of Fallot

BACKGROUND This study aimed to identify the clinical predictors of the degree of right ventricular (RV) myocardial fibrosis in patients with repaired tetralogy of Fallot (TOF) with special focus on the RV pressure load.Methods and Results:From April 2004 to March 2017, 30 patients with repaired TOF underwent pulmonary valve replacement and concomitant RV myocardial biopsy. The stroke volume ratio (RV stroke volume/left ventricular stroke volume), RV end-diastolic volume index, and right-to-left ventricular systolic pressure ratio were evaluated with respect to their prognostic value for the degree of RV myocardial fibrosis. Significant positive linear correlations were detected between the stroke volume ratio and the degree of RV myocardial fibrosis (P=0.003, r=0.52). Patients with a right-to-left ventricular systolic pressure ratio >0.45 showed a significantly greater degree of RV myocardial fibrosis under an equivalent stroke volume ratio. CONCLUSIONS Under conditions of RV volume overload, a right-to-left ventricular systolic pressure ratio >0.45 was a predisposing factor for progression of RV myocardial fibrosis in patients with repaired TOF.

Clinical standard for valve area after common atrioventricular valve plasty for a single ventricle

OBJECTIVES To determine a clinical standard for post-repair common atrioventricular valve orifice area based on mid- to long-term valve function in patients with a functional single ventricle. METHODS The medical records of 19 single-ventricle patients who underwent common atrioventricular valve plasty from July 1988 to January 2013 were retrospectively reviewed. Bivalvation valvuloplasty was performed in 7 patients with relatively hypoplastic leaflets. The relationship between the orifice area of the repaired common atrioventricular valve measured intraoperatively and valve function and ventricular volume in the early postoperative period (median, 9.5 months) and at mid- to long-term follow-up (median, 4 years) were analysed. RESULTS Post-repair valve area was significantly positively correlated with valve regurgitation severity in the early postoperative period (P = 0.001, r = 0.69) and at mid- to long-term follow-up (P = 0.02, r = 0.57). Patients who did not undergo bivalvation had favourable valve function at mid- to long-term follow-up and in the early postoperative period when the post-repair valve area was 96-136% of the normal mitral valve area. Bivalvation patients had significantly more valve regurgitation in the early postoperative period than patients without bivalvation, despite equivalent repaired valve area (P = 0.02). CONCLUSIONS The post-repair orifice area of the common atrioventricular valve is significantly related to postoperative valve function. The clinical standard of post-repair valve orifice area might be 96-136% of the normal mitral valve area in patients undergoing repair without bivalvation. Patients undergoing bivalvation require greater reduction to obtain favourable mid- to long-term valve function.

Staged repair of hemitruncus without prosthetic material.

Right pulmonary artery banding was performed in a patient with right hemitruncus at 17 days of age, due to severe hypertension in both pulmonary arteries and severely reduced right ventricular contraction. Following the procedure, the pulmonary hypertension and right ventricular contraction gradually improved with pulmonary vasodilator administration, and total correction was achieved two months later. A cardiac catheter examination at the 1-year follow-up showed normal pressure in both pulmonary arteries and good right ventricular contraction.