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Biomedical subjects

Minoru Yoshiyama

Publications and source records attributed to Minoru Yoshiyama.

At least 55 records · Page 3Linked to original sources
PubMed2005

Prevalence and clinical course of the juveniles with Brugada-type ECG in Japanese population.

BACKGROUND: Although many studies on Brugada syndrome have been done, with many reports of genetic findings and clinical features, little evidence exists to support the role of this syndrome in sudden cardiac death in a juvenile population. We sought to determine the prevalence and clinical course in children exhibiting Brugada-type ECG in a community-based population. METHODS: Our study population comprised 21,944 subjects (11,282 boys and 10,662 girls) who underwent ECG during their first-year elementary school health examinations between 1992 and 2001 in Izumi City, Osaka. Brugada-type ECG was defined as demonstrating ST-segment elevation (coved or saddle-back type, J wave amplitude > or =0.2 mV) in the right precordial leads. We also divided Brugada-type ECGs into three types according to a consensus report. Type 1: coved ST-segment elevation displaying high J wave amplitude followed by a negative T wave; Type 2: high take-off and gradually descending ST-segment elevation (remaining > or =1 mm) followed by a positive or biphasic T wave; and Type 3: ST-segment elevation of <1 mm of both types. RESULTS: Four subjects showed Brugada-type ECG (0.02%) (2 boys and 2 girls). Only one subject, a girl, met Type 1 criteria (0.005%). No history of structural heart disease was documented in these four subjects. During 6.8 +/- 1.0 years of follow-up, no episode of unexpected sudden death, syncopal attack, and fatal arrhythmia occurred. CONCLUSIONS: The prevalence of Brugada-type ECG in a juvenile population was extremely low. To investigate when the typical Brugada-type ECG might be manifested, it could be necessary to check ECGs after adolescence.

Bundle-Branch Block↗
PubMed2005

Impaired coronary circulation in patients with apical hypertrophic cardiomyopathy: noninvasive analysis by transthoracic Doppler echocardiography.

OBJECTIVES: We designed this study to examine the characteristics of coronary circulation in patients with apical hypertrophic cardiomyopathy (ApHCM) using noninvasive transthoracic Doppler echocardiography (TTDE). BACKGROUND: Recent advances in TTDE have allowed noninvasive assessment of coronary circulation by the measurement of coronary flow velocity (CFV) patterns and coronary flow velocity reserve (CFVR). However, there have been no previous studies evaluating coronary circulation in ApHCM. METHODS: We analyzed CFV and CFVR in the left anterior descending coronary artery (LAD), and apical wall thickness in the left ventricle, in 10 ApHCM subjects and 10 control subjects. Mean diastolic velocity (MDV) and time from the beginning of diastole to peak velocity (TPV), and CFVR, defined as a ratio of drug-induced hyperemic to basal MDV, were measured. RESULTS: At baseline, MDV was higher, and TPV was longer, in ApHCM subjects than in control subjects (29 +/- 5.7 versus 19 +/- 6.5 cm/sec; p < 0.01 and 5.2 +/- 1.0 versus 3.5 +/- 0.6 msec; p < 0.005, respectively). CFVR in ApHCM subjects was significantly lower than in control subjects (1.9 +/- 0.4 versus 3.1 +/- 0.8; p < 0.005). CFVR and basal MDV in ApHCM subjects showed significant correlations with apical/posterior wall thickness ratio [CFVR; r =-0.84, p < 0.01 and MDV; r = 0.74, p < 0.05, respectively]. CONCLUSION: Noninvasive coronary flow assessment by TTDE revealed an impaired coronary circulation with reduced CFVR, high MDV at baseline and prolonged TPV. These results suggest that these characteristics of coronary circulation may provide an additional index for the assessment of ApHCM.

Adenosine Triphosphate↗
PubMed2005

Selective endothelin ET(B) receptor antagonist improves left ventricular function but exaggerates degeneration of cardiomyocytes in J2N-k hamsters.

BACKGROUND: Endothelin-1 (ET-1) receptor antagonist is expected to improve the prognosis of patients with heart failure, but the role of the ET(B) receptor in cardiac function and structure is complicated. In the present study the NADPH diaphorase activity and ET-1 content in the failing heart treated with ET(A) or ET(B) receptor antagonist were evaluated in a model of dilated cardiomyopathy. METHODS AND RESULTS: Selective ET(A) receptor antagonist, ABT-627 (10 mg/kg per day), or selective ET(B) antagonist, A-192621 (30 mg/kg per day), was given to 22-week-old J2N-k cardiomyopathic hamsters for 8 weeks. The effects of ABT-627 and A-192621 on cardiac function, left ventricular (LV) histology, ET-1 content and NADPH diaphorase activity in the LV were evaluated. Treatment with ABT-627, but not A-192621, significantly decreased ET-1 content and NADPH diaphorase activity. Although the improvement of LV function was modest, ABT-627 prevented tissue damage in J2N-k hamsters. In contrast, A-192621 worsened the degeneration of cardiomyocytes despite improving hemodynamic parameters. CONCLUSIONS: Selective ET(A) antagonist, but not ET(B) antagonist, reduced the ET-1 content as well as the NADPH diaphorase activity, and preserved the fine structure of LV myocardium in cardiomyopathic hamsters. Long-term blockade of ET(B) receptor might worsen the degeneration of cardiomyocytes through the ET-1/ET(A) system even if LV function could be improved.

Animals↗
PubMed2005

Mechanisms of combined treatment with celiprolol and candesartan for ventricular remodeling in experimental heart failure.

BACKGROUND: Both beta-adrenergic blockers and angiotensin-II receptor blockers were reported to improve the prognosis of patients with heart failure, but the efficacy of combination therapy with these agents has not been fully elucidated. Also the efficacy of celiprolol, a beta1-selective adrenoceptor antagonist with partial beta2-agonist properties, for heart failure treatment is still controversial. We examined the cardioprotective effects and mechanisms of the therapy with celiprolol or candesartan, an angiotensin-II receptor blockers and their combination in heart failure induced by isoproterenol (ISO). METHODS AND RESULTS: ISO 300 mg/kg was injected in rats to produce heart failure. Two months after the injection, the ISO-injected rats were divided into 4 groups (8 rats each) and treated for 4 weeks as follows: (a) vehicle; (b) celiprolol 10 mg/kg per day (BB); (c) candesartan 0.2 mg/kg per day (ARB); and (d) their combination BB+ARB. ISO significantly elevated left ventricular (LV) end-diastolic pressure, decreased peak-negative dP/dt and LV ejection fraction. BB and ARB similarly ameliorated cardiac dysfunction due to ISO, but BB+ARB were more potent than the individual therapies. Separately, ARB preserved the histological structure in LV myocardium. In contrast, BB ameliorated calcium handling, as shown by the increased ratio of SERCA2 to phospholamban protein, despite having little effect on the histology. CONCLUSION: Both celiprolol and candesartan showed cardioprotective effects in this heart failure model. The potential use of the combination treatment in heart failure might result in a synergistic effect through the different cardioprotective mechanisms of celiprolol and candesartan.

Animals↗
PubMed2005

Left ventricular remodeling after myocardial infarction in antecedent hypertensive patients.

Antecedent hypertension adversely affects mortality and heart failure after myocardial infarction (MI). In addition, accelerated ventricular remodeling is a contributor to the increased mortality observed after MI. The purpose of this study was to assess the relationship of antecedent hypertension to ventricular remodeling after MI. Ninety-four patients presenting with a first acute MI who were treated with reperfusion therapy within 12 h of their symptom onset were enrolled in this study. All of them underwent left ventriculography immediately after reperfusion therapy and again at 6 months after the occurrence of MI. Patients were divided into two groups: a hypertensive group and a normotensive group. End-diastolic volume index (EDVI), end-systolic volume index (ESVI), and ejection fraction (EF) values in the acute phase were compared to those at 6 months after acute MI in either group. The hypertensive group showed a significant increase in both EDVI and ESVI after 6 months, whereas the normotensive group did not. In addition, there was no change in EF in the hypertensive group, whereas EF increased significantly after 6 months in the normotensive group. As a result, the percent changes in ESVI and EF were significantly different between the hypertensive group and normotensive group. The results demonstrated that antecedent hypertension interacts with ventricular cavity dilatation after MI.

Aged↗
PubMed2005

Excess aldosterone under normal salt diet induces cardiac hypertrophy and infiltration via oxidative stress.

Aldosterone is known to play a role in the pathophysiology of some cardiovascular diseases. However, previous studies on aldosterone infusion have been mostly performed in animals receiving sodium loading and uninephrectomy, and thus the cardiac action of aldosterone alone remains to be fully clarified. The present study was undertaken to investigate the direct cardiac action of aldosterone infusion alone in rats not subjected to salt loading and uninephrectomy. Aldosterone (0.75 microg/h) was subcutaneously infused into rats via an osmotic minipump for 14 days. Aldosterone infusion, under a normal salt diet, induced only a slight increase in the blood pressure of normal rats throughout the infusion. However, aldosterone significantly induced cardiac hypertrophy, as shown by echocardiography and measurement of cardiomyocyte cross-sectional area. Furthermore, aldosterone caused not only cardiac interstitial macrophage infiltration but also cardiac focal inflammatory lesions, which were associated with an increase in cardiac monocyte chemoattractant protein-1 (MCP-1) and osteopontin mRNA. The slight elevation of blood pressure by aldosterone infusion was completely prevented by tempol, the superoxide dismutase mimetic. However, tempol failed to suppress cardiac hypertrophy, the formation of inflammatory lesions, and upregulation of cardiac MCP-1 and osteopontin by aldosterone, while N-acetylcysteine could inhibit all of them. Our data provide evidence that aldosterone alone can induce cardiac hypertrophy and severe inflammatory response in the heart, independently of blood pressure, even in the absence of salt loading or nephrectomy. Aldosterone seems to induce cardiac inflammation and gene expression via oxidative stress that is inhibited by N-acetylcysteine but not by tempol.

Acetylcysteine↗
PubMed2005

Effects of granulocyte-colony stimulating factor on cardiac remodeling after myocardial infarction.

BACKGROUND: Recent studies suggest that granulocyte colony-stimulating factor (G-CSF) may be beneficial in the treatment of myocardial infarction (MI). However, the effects of G-CSF on MI are still controversial and the molecular mechanism of G-CSF treatment for repair of the infarcted heart is not fully understood. METHODS: Mice were divided into three groups: Control, MI and MI treated with G-CSF. Four weeks after MI, we examined cardiac function by Doppler echocardiography and measured non-infarcted myocardial mRNA expression by northern blot analysis. RESULTS: Cardiac function decreased significantly in the MI groups compared with the sham-operated groups. Additionally, the ratios of E wave to A wave peak velocity (E/A) in the MI groups were higher than in the control group. E/A in G-CSF MI mice was significantly lower than in control MI mice (p<0.01). Matrix metalloproteinase-2 (MMP-2) mRNA expression was significantly increased in the MI groups compared with the control group (p<0.01). Furthermore, mRNA expression in the G-CSF MI group was significantly higher than in the Control MI group (p<0.05). CONCLUSIONS: G-CSF can prevent the LV remodeling process after MI that accompanies progressive cardiac dysfunction. One of the mechanisms of G-CSF treatment for cardiac remodeling after MI may be overexpression of MMP-2 in non-infarcted myocardium.

Animals↗
PubMed2004

Core protein of hepatitis C virus induces cardiomyopathy.

Hepatitis C virus (HCV) has been reported to be associated with cardiomyopathy. However, the mechanism of cardiomyopathy in chronic HCV infection is still unclear. Therefore, we investigate the development of cardiomyopathy in mice transgenic for the HCV-core gene. After the age of 12 months, mice developed cardiomyopathy that appeared as left ventricular dilatation, and systolic and diastolic dysfunction assessed by Doppler echocardiography. Histologically, hypertrophy of cardiomyocytes, cardiac fibrosis, disarray and scarcity of myofibrils, vacuolization and deformity of nuclei, myofibrillar lysis, streaming of Z-bands, and an increased number of bizarre-shaped mitochondria were found in HCV-core transgenic mice. These histological changes are just consistent with cardiomyopathy. In conclusion, the HCV-core protein directly plays an important role in the development of cardiomyopathy.

Actin Cytoskeleton↗
PubMed2004

Effect of azithromycin therapy on coronary circulation in patients with coronary artery disease.

This study examined the effect of azithromycin therapy on the coronary microcirculation using measurement of coronary flow velocity reserve (CFVR) by transthoracic Doppler echocardiography in 35 patients with coronary artery disease. CFVR increased significantly after azithromycin therapy (3.0 +/- 0.7 vs 3.5 +/- 0.7, p <0.001). The changes in CFVR were negatively correlated with changes in high-sensitivity C-reactive protein levels in patients receiving azithromycin.

Aged↗
PubMed2004

Spotty calcification typifies the culprit plaque in patients with acute myocardial infarction: an intravascular ultrasound study.

BACKGROUND: Calcification is a common finding in human coronary arteries; however, the relationship between calcification patterns, plaque morphology, and patterns of remodeling of culprit lesions in a comparison of patients with acute coronary syndromes (ACS) and those with stable conditions has not been documented. METHODS AND RESULTS: Preinterventional intravascular ultrasound (IVUS) images of 178 patients were studied, 61 with acute myocardial infarction (AMI), 70 with unstable angina pectoris (UAP), and 47 with stable angina pectoris (SAP). The frequency of calcium deposits within an arc of less than 90 degrees for all calcium deposits was significantly different in culprit lesions of patients with AMI, UAP, and SAP (P<0.0001). Moreover, the average number of calcium deposits within an arc of <90 degrees per patient was significantly higher in AMI than in SAP (P<0.0005; mean+/-SD, AMI 1.4+/-1.3, SAP 0.5+/-0.8). Conversely, calcium deposits were significantly longer in SAP patients (P<0.0001; mean+/-SD, AMI 2.2+/-1.6, UAP 1.9+/-1.8, and SAP 4.3+/-3.2 mm). In AMI patients, the typical pattern was spotty calcification, associated with a fibrofatty plaque and positive remodeling. In ACS patients showing negative remodeling, no calcification was the most frequent observation. Conversely, SAP patients had the highest frequency of extensive calcification. CONCLUSIONS: Our observations show that IVUS allows the identification of vulnerable plaques in coronary arteries, not only by identifying a fibrofatty plaque and positive remodeling, but also by identifying a spotty pattern of calcification.

Aged↗
PubMed2004

Accuracy of measurement of left ventricular volume and ejection fraction by new real-time three-dimensional echocardiography in patients with wall motion abnormalities secondary to myocardial infarction.

Three-dimensional echocardiography is an ideal tool for the measurement of left ventricular (LV) volume because no geometric assumptions about LV shape are needed. The introduction of new real-time 3-dimensional echocardiography (RT3DE) has allowed rapid acquisition of a 3-dimensional dataset with good image quality. The purpose of this study was to examine the accuracy of RT3DE for the measurement of LV volume and ejection fraction in patients with wall motion abnormalities by using quantitative gated single-photon emission computed tomography (QGSPECT) as a reference standard. The study population consisted of 25 consecutive patients with wall motion abnormalities who underwent LV volume measurement by 2-dimensional echocardiography and by QGSPECT. LV volume and ejection fraction by RT3DE were measured offline by using the average rotation method. In 23 of 25 patients (92%), it was possible to measure 3-dimensional volume with RT3DE. RT3DE correlated well with QGSPECT in the measurement of end-diastolic volume and end-systolic volume (r = 0.97, mean difference 3.4 ml; r = 0.98, mean difference 2.0 ml, respectively), 2-dimensional echocardiography also correlated with QGSPECT but underestimated LV volume (r = 0.98, mean difference 21.1 ml; r = 0.98, mean difference 15.6 ml, respectively). Ejection fraction obtained by RT3DE had better agreement with that obtained by QGSPECT than that obtained by 2-dimensional echocardiography (r = 0.92, mean difference -0.2%; r = 0.89, mean difference -2.7%, respectively). RT3DE allows convenient and accurate estimation of LV volume and ejection fraction in patients with wall motion abnormalities.

Adult↗
PubMed2004

Black tea increases coronary flow velocity reserve in healthy male subjects.

Epidemiologic studies suggest that tea consumption decreases the risk for cardiovascular events. However, there has been no clinical report examining the effects of tea consumption on coronary circulation. The purpose of this study was to evaluate the effects of black tea on coronary flow velocity reserve (CFVR) using transthoracic Doppler echocardiography (TTDE). This was a double-blind crossover study of 10 healthy male volunteers conducted to compare the effects of black tea and caffeine on coronary circulation. The coronary flow velocity of the left anterior descending coronary artery was measured at baseline and at hyperemia during adenosine triphosphate infusion by TTDE to determine CFVR. The CFVR ratio was defined as the ratio of CFVR after beverage consumption to CFVR before beverage consumption. All data were divided into 2 groups according to beverage type: group T (black tea) and group C (caffeine). Two-way analysis of variance showed a significant group effect and interaction in CFVR before and after beverage consumption (p = 0.001). CFVR significantly increased after tea consumption in group T (4.5 +/- 0.9 vs 5.2 +/- 0.9, p <0.0001). The CFVR ratio of group T was larger than that of group C (1.18 +/- 0.07 vs 1.04 +/- 0.08, p = 0.002). Acute black tea consumption improves coronary vessel function, as determined by CFVR.

Adult↗
PubMed2004

Circulating monocytes and in-stent neointima after coronary stent implantation.

OBJECTIVES: The aim of this study was to investigate the relationship between circulating monocytes and in-stent neointimal volume at six-month follow-up. BACKGROUND: In-stent neointimal hyperplasia is the main contributing factor to in-stent restenosis. There is increasing evidence that white blood cells (WBCs), especially monocytes, play a central role in restenosis after stent implantation. METHODS: We performed coronary stent implantation in 107 patients (107 lesions). Peripheral blood was obtained from all patients immediately before coronary angiography and every day for seven days after the intervention, and each WBC fraction count was analyzed. At scheduled six-month follow-up, all patients received angiographic and volumetric intravascular ultrasound analysis. RESULTS: The circulating monocyte count increased and reached its peak two days after stent implantation (from 350 +/- 167 to 515 +/- 149/mm3, p < 0.01). The maximum monocyte count after stent implantation showed a significant positive correlation with in-stent neointimal volume at six-month follow-up (r = 0.44, p < 0.0001). Other fractions showed neither significant serial changes nor a correlation with in-stent neointimal volume. Multiple regression analysis revealed that in-stent neointimal volume was independently correlated with stent volume immediately after implantation (r = 0.45, p < 0.0001) and maximum monocyte count (r = 0.35, p < 0.001). Angiographic restenosis, defined as percent diameter stenosis >50%, was observed in 22 patients (21%), and these patients showed a significantly larger maximum monocyte count than patients without restenosis (642 +/- 110 vs. 529 +/- 77/mm3, p < 0.01). CONCLUSIONS: Circulating monocytes increased after coronary stent implantation, and the peak monocyte count related to in-stent neointimal volume. Our results suggest that circulating monocytes play a role in the process of in-stent neointimal hyperplasia.

Angioplasty, Balloon, Coronary↗
PubMed2004

Oolong tea increases plasma adiponectin levels and low-density lipoprotein particle size in patients with coronary artery disease.

BACKGROUND: Oolong tea has been studied for its effect on cardiovascular disease and obesity. Plasma adiponectin levels are reduced in obesity, in patients with type 2 diabetes mellitus and in coronary artery disease (CAD). OBJECTIVE: To investigate prospectively, whether intake of Oolong tea influences plasma adiponectin levels, low-density lipoprotein (LDL) particle size, total cholesterol, high-density lipoprotein (HDL) cholesterol, LDL cholesterol, serum triglyceride and plasma glucose levels in patients with CAD. METHODS: Twenty two patients in our study consumed Oolong tea (1000 ml) or water for 1 month in our randomized cross-over study design. RESULTS: There was a significant difference in plasma adiponectin levels before and after 1 month intake of Oolong tea (6.26 +/- 3.26 microg/ml versus 6.88 +/- 3.28 microg/ml, P < 0.05), and in plasma level LDL particle size (25.02+/-0.67 nm versus 25.31+/-0.60 nm, P < 0.01). The water-consuming control group showed no changes (6.28+/-3.28 microg/ml versus 6.23+/-3.21 microg/ml) in adiponectin levels or LDL particle sizes (25.03+/-0.70 nm versus 25.02+/-0.72 nm). We also observed a significant difference in hemoglobin A1c levels (7.23 +/- 4.45% versus 6.99 +/- 4.30%, P < 0.05) before and after intake of Oolong tea. CONCLUSION: Oolong tea may have beneficial effects on the progression of atherosclerosis in patients with CAD.

Adiponectin↗
PubMed2004

Simple detection of occluded coronary artery using retrograde flow in septal branch and left anterior descending coronary artery by transthoracic Doppler echocardiography at rest.

BACKGROUND: We hypothesized that coronary flow assessment by transthoracic Doppler echocardiography (TTDE) for both intramyocardial collateral channel and epicardial channels would be useful for identifying occluded left anterior descending coronary artery (LAD). METHODS: We assessed flow direction in the LAD and the septal branch (SEP) by TTDE in 302 consecutive patients who were suggested to have ischemic heart disease. We defined antegrade LAD flow as a direction from the base to the apex of the left ventricle in the anterior groove area, and antegrade SEP flow as a direction from anterior to inferior in the anterior interventricular septum. By contrast, we defined retrograde LAD and SEP flow as an inverse direction. We performed angiography on all patients. RESULTS: Retrograde flow was detected in 22 (LAD, 16 patients; SEP, 6 patients) of 23 patients with occluded LAD, and antegrade flow was detected in all patients without occluded LAD. The sensitivity and specificity for identification of occluded LAD by TTDE were 96% and 100%, respectively. CONCLUSIONS: Assessment of flow direction in both LAD and SEP by TTDE is a useful method in identification of occluded LAD.

Aged↗
PubMed2004

Quantitative intravenous myocardial contrast echocardiography predicts recovery of left ventricular function after revascularization in chronic coronary artery disease.

BACKGROUND: Quantitative intravenous myocardial contrast echocardiography (MCE) has been shown to measure regional myocardial blood flow velocity noninvasively. PURPOSE: To determine whether quantitative intravenous MCE could be used clinically to predict functional recovery after revascularization in patients with chronic coronary artery disease. METHODS: Twenty-eight patients with chronic stable coronary artery disease and resting regional left ventricular dysfunction were included in this study. The study permits myocardial perfusion analysis by intravenous MCE before revascularization with continuous infusion of Levovist and intermittent ultrasonic exposure. Wall motion assessment by echocardiography at rest was repeated after long-term follow-up period (7 +/- 2 months). In dysfunctional segments, we analyzed myocardial perfusion quantitatively by fitting to an exponential function, Y = A(1 - e-betat) to obtain the rate of rise (beta) of background-subtracted intensity, which represented myocardial blood flow velocity. RESULTS: Of the 101 revascularized dysfunctional segments, MCE was adequately visualized in 91 (90%) segments, and wall motion was recovered in 45 (49%) segments. The value of beta in the recovery segments was significantly higher than that in nonrecovery segments (0.80 +/- 0.50 vs 0.39 +/- 0.24, P < 0.001). The value of beta > 0.5 predicted recovery of segmental function with a sensitivity of 71%, specificity of 78%. CONCLUSION: Quantitative intravenous MCE can predict functional recovery after revascularization in patients with chronic coronary artery disease.

Aged↗