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Biomedical subjects

Yoshiyuki Furuse

Publications and source records attributed to Yoshiyuki Furuse.

8 recordsLinked to original sources

Transient left ventricular apical ballooning in a patient with bicuspid aortic valve created a left ventricular thrombus leading to acute renal infarction.

A 44-year-old woman had tako-tsubo-like ventricular dysfunction with chest pain and ST segment elevation on the ECG. Echocardiography revealed a bicuspid aortic valve with moderate to severe aortic regurgitation. She developed mild heart failure during the clinical course, but the medication (furosemide, enalapril, and asprin) had to be stopped because of skin eruptions. Four weeks after ceasing the antiplatelet agent, she was re-admitted with acute renal infarction. Enhanced chest computed tomography revealed a filling defect in the left ventricle and echocardiography showed a high echogenic mass in the left ventricular apical wall. These findings strongly suggested that the renal infarction was caused by an embolism derived from a left ventricular thrombus that formed during the clinical course of the transient left ventricular apical ballooning. Anticoagulation therapy with urokinase and warfarin successfully lysed the thrombus. Left ventricular thrombus should be considered a complication of transient left ventricular apical ballooning, especially in patients with organic heart disease.

Acute Disease↗

Neurohumoral profiles in patients with hypertrophic cardiomyopathy: differences to hypertensive left ventricular hypertrophy.

BACKGROUND: Patients with hypertrophic cardiomyopathy (HCM) or hypertensive heart disease (HHD) have increased concentrations of various neurohumoral factors. Thus, the aim of the present study was to evaluate the differences in the neurohumoral profiles of HCM and HHD. METHODS AND RESULTS: Plasma concentrations of epinephrine, norepinephrine, atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), angiotensin II and endothelin-1 were measured in 40 patients with HCM, 35 with HHD, and 15 controls. Additionally, the concentrations of these neurohumoral factors in the coronary sinus and aortic root were measured in 12 HCM patients and 10 controls. Plasma concentrations of norepinephrine, ANP and BNP were significantly higher in HCM than HHD and controls. In HCM, there was no significant correlation between the left ventricular mass index and any neurohumoral factor. The plasma BNP concentration significantly correlated with left intraventricular pressure gradient in HCM. There were significant differences in the plasma concentrations of ANP and BNP between HCM with and without left ventricular diastolic dysfunction. Transcardiac production of BNP was significantly higher in patients with obstructive HCM than in those with non-obstructive HCM. CONCLUSIONS: The significant neurohumoral differences between HCM and HHD were the plasma concentrations of norepinephrine, ANP and BNP. In HCM patients, the plasma BNP concentration may reflect the intraventricular pressure gradient and left ventricular diastolic dysfunction whereas the plasma ANP concentration reflects only the left ventricular diastolic dysfunction.

Aged↗

[Clinical features of coronary artery ectasia].

OBJECTIVES: To investigate the clinical significance of coronary artery ectasia in Japanese patients. METHODS: Coronary artery ectasia was found in 54 of 3,778 (1.4%) consecutive patients who underwent coronary angiography. The clinical characteristics and the coronary angiographic findings of these patients were studied. Follow-up data were obtained for 49 patients, who were separated into two groups: Group A subsequently suffered a follow-up major cardiac event, and Group B did not develop such an event. RESULTS: Among the coronary artery ectasia patients, 65% had myocardial infarction, 91% had coronary artery disease, and 48% had single-vessel disease. Seventy-six percent had single-vessel involvement with coronary artery ectasia. Eighteen patients (37%) suffered 22 follow-up major events. Seventy-two percent of the first follow-up event cases occurred within 4 years after the first cardiac event. The follow-up event in 78% of cases was acute coronary syndrome. There were no significant differences in age and prevalence of each coronary artery risk factor between Groups A and B. There were no significant differences in the incidence of follow-up event between the patients with single-vessel disease and the patients with multi-vessel disease, nor between the patients with single-vessel involvement with coronary artery ectasia and the patients with multi-vessel involvement with coronary artery ectasia. There was no significant difference in the percentage of patients in whom the culprit vessel of the cardiac event was the same as the ectatic vessel between the first cardiac event and follow-up cardiac events (41% vs 62%). CONCLUSIONS: Coronary artery ectasia is not benign and must be carefully monitored. Coronary atherosclerosis may contribute to the occurrence of subsequent cardiac events.

Coronary Artery Disease↗

Allopurinol improves cardiac dysfunction after ischemia-reperfusion via reduction of oxidative stress in isolated perfused rat hearts.

It has been reported that the xanthine oxidase inhibitor, allopurinol, has a protective effect on ischemia - reperfusion injury, but the precise mechanism of its action is still unclear. Therefore, in the present study the mechanisms of the myocardial protection of allopurinol were evaluated in isolated perfused rat hearts. Allopurinol significantly inhibited myocardial xanthine oxidase activity, and improved left ventricular dysfunction after ischemia - reperfusion. In addition, the lactate dehydrogenase content in the coronary effluent obtained after reperfusion was significantly decreased. ATP, ADP, AMP and IMP significantly decreased, whereas inosine, hypoxanthine and xanthine significantly increased after ischemia in both the control and allopurinol groups. The concentration of xanthine was significantly decreased after ischemia - reperfusion in the allopurinol group; however, allopurinol did not affect the other purine metabolites. To evaluate the accumulation of oxidative stress, thiobarbituric acid reactive substances (TBARS) production in myocardial tissue was measured and allopurinol significantly decreased TBARS formation after ischemia - reperfusion. Finally, myocardial hydroxyl radicals were directly measured by electron spin resonance spectroscopy with the nitroxide radical 4-hydroxy-2, 2,6,6-tetramethyl-piperidine-N-oxyl. Hydroxyl radicals significantly increased immediately after reperfusion, but were significantly decreased in the allopurinol group. In conclusion, allopurinol reduced myocardial injury after ischemia-reperfusion by suppressing oxidative stress, but not by salvage of ATP. These findings may lead to the development of new therapeutic strategies for myocardial ischemia - reperfusion injury.

Adenine Nucleotides↗

Analysis of moricizine block of sodium current in isolated guinea-pig atrial myocytes. Atrioventricular difference of moricizine block.

The effects of moricizine on Na+ channel currents (INa) were investigated in guinea-pig atrial myocytes and its effects on INa in ventricular myocytes and on cloned hH1 current were compared using the whole-cell, patch-clamp technique. Moricizine induced the tonic block of INa with the apparent dissociation constant (Kd,app) of 6.3 microM at -100 mV and 99.3 microM at -140 mV. Moricizine at 30 microM shifted the h infinity curve to the hyperpolarizing direction by 8.6 +/- 2.4 mV. Moricizine also produced the phasic block of INa, which was enhanced with the increase in the duration of train pulses, and was more prominent with a holding potential (HP) of -100 mV than with an HP of -140 mV. The onset block of INa induced by moricizine during depolarization to -20 mV was continuously increased with increasing the pulse duration, and was enhanced at the less negative HP. The slower component of recovery of the moricizine-induced INa block was relatively slow, with a time constant of 4.2 +/- 2.0 s at -100 mV and 3.0 +/- 1.2 s at -140 mV. Since moricizine induced the tonic block of ventricular INa with Kd,app of 3.1 +/- 0.8 microM at HP = -100 mV and 30.2 +/- 6.8 microM at HP = -140 mV, and cloned hH1 with Kd,app of 3.0 +/- 0.5 microM at HP = -100 mV and 22.0 +/- 3.2 microM at HP = -140 mV, respectively, either ventricular INa or cloned hH1 had significantly higher sensitivity to moricizine than atrial INa. The h infinity curve of ventricular INa was shifted by 10.5 +/- 3.5 mV by 3 microM moricizine and that of hH1 was shifted by 5.0 +/- 2.3 mV by 30 microM moricizine. From the modulated receptor theory, we have estimated the dissociation constants for the resting and inactivated state to be 99.3 and 1.2 microM in atrial myocytes, 30 and 0.17 microM in ventricular myocytes, and 22 and 0.2 microM in cloned hH1, respectively. We conclude that moricizine has a higher affinity for the inactivated Na+ channel than for the resting state channel in atrial myocytes, and moricizine showed the significant atrioventricular difference of moricizine block on INa. Moricizine would exert an antiarrhythmic action on atrial myocytes, as well as on ventricular myocytes, by blocking Na+ channels with a high affinity to the inactivated state and a slow dissociation kinetics.

Animals↗

Troglitazone improves cardiac function in patients with congestive heart failure.

Troglitazone increased cardiac output and stroke volume, as a result of decreased peripheral resistance, in diabetic patients with normal cardiac function. The cardiovascular effects of troglitazone in patients with heart failure are unknown. The aim of the study was to evaluate the cardiovascular effects of troglitazone in patients with heart failure. Blood pressure and echocardiographic findings were evaluated before and 1, 2, 3 and 4 hours after a single dose of troglitazone (400 mg) or placebo, in eight type II diabetic patients with congestive heart failure. The plasma catecholamines and coefficient of variance of RR intervals (CVRR) were also measured. Neither heart rate nor blood pressure changed after the administration of troglitazone. Left ventricular (LV) end-diastolic dimension did not change either, however, the LV end-systolic dimension significantly decreased compared with its baseline value and with that of the placebo group. On the other hand, the % fractional shortening and the E/A ratio increased significantly after troglitazone. The LV end-diastolic volume did not change, whereas the LV end-systolic volume significantly decreased. The stroke volume and the LV ejection fraction significantly increased compared with its baseline value and with that of the placebo group. The peripheral vascular resistance did not change after the administration of troglitazone, whereas plasma catecholamines significantly decreased, and CVRR remained unchanged in both groups. These hemodynamic changes suggest that a single oral dose of troglitazone induced inotropy without activation of the sympathetic nervous system.

Blood Pressure↗

Parathyroid hormone-related protein is produced in the myocardium and increased in patients with congestive heart failure.

PTHrP is produced in a wide variety of different cells, including cardiomyocytes. Its production is augmented by mechanical and neurohumoral stimulation, and PTHrP has positive chronotropic and vasodilatory effects. Thus, in the heart, PTHrP has the potential to serve as a mechano-sensitive regulatory molecule. We evaluated peripheral and central levels of PTHrP in patients with congestive heart failure (CHF) and tested the hypothesis that PTHrP is released from the heart in patients with CHF. Intact full-length PTHrP (i-PTHrP) and C-terminal PTHrP (c-PTHrP) levels were measured in the plasma of 64 patients with CHF and 12 controls. Plasma PTHrP concentrations in the coronary sinus and aortic root were also measured in 18 CHF patients and 10 controls. Both plasma i-PTHrP and c-PTHrP levels in CHF patients were significantly higher than control levels and increased as a function of New York Heart Association classification. There were significant correlations between c-PTHrP levels and plasma norepinephrine, brain natriuretic peptide, angiotensin II, and endothelin-1 levels. Plasma i-PTHrP was significantly correlated with left ventricular ejection fraction and end-diastolic and end-systolic dimensions. Plasma i-PTHrP levels were significantly higher in the coronary sinus than in the aortic root in CHF patients, but among controls concentrations of i-PTHrP were indistinguishable at these two sites. This is the first report demonstrating that PTHrP is produced in the myocardium and is increased in CHF; these findings suggest that PTHrPs levels might be modulated by cardiac performance in patients with CHF.

Adult↗