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Biomedical subjects

Toshiaki Ebina

Publications and source records attributed to Toshiaki Ebina.

At least 19 recordsLinked to original sources
PubMed2006

Combined prognostic utility of ST segment in lead aVR and troponin T on admission in non-ST-segment elevation acute coronary syndromes.

Many studies have shown that ST-segment depression is a strong predictor of poor outcomes in patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACSs); however, lead aVR was not considered in these studies. The present study examined the prognostic usefulness of the 12-lead electrocardiogram in combination with biochemical markers in 333 patients with NSTE-ACS. ST-segment deviation of > or =0.5 mm was considered clinically significant. Coronary angiography was performed a median of 3 days after admission in all patients. The primary end point was the composite of death, myocardial infarction, and urgent revascularization at 90 days. ST-segment elevation in lead aVR (odds ratio 13.8, 95% confidence interval 1.43 to 100.9, p = 0.03) and increased troponin T (odds ratio 7.9, 95% confidence interval 1.22 to 123.8, p = 0.04) were the only independent predictors of restricted events (death or myocardial infarction) at 90 days. ST-segment elevation in lead aVR (odds ratio 12.8, 95% confidence interval 4.80 to 33.9, p < 0.0001) and increased troponin T (odds ratio 2.03, 95% confidence interval 1.20 to 4.29, p = 0.04) were also the only independent predictors of adverse events (death, myocardial infarction, or urgent revascularization) at 90 days. When ST-segment status in lead aVR was combined with troponin T, patients with ST-segment elevation in lead aVR and increased troponin T had the highest rates of left main or 3-vessel coronary disease (62%) and 90-day adverse outcomes (47%). In conclusion, our findings suggest that ST-segment status in lead aVR combined with troponin T on admission is a simple and useful clinical tool for early risk stratification in patients with NSTE-ACS.

Aged↗
PubMed2006

Adenosine concentration in great cardiac vein is increased in non-ventricular fibrillation dogs.

This study was conducted to clarify the relationship between myocardial endogenous adenosine concentration in the great cardiac vein during ischemia and reperfusion-induced ventricular fibrillation (VF) and the occurrence rate of ischemia and reperfusion-induced VF. Sixty anesthetized mongrel dogs were subjected to 10-min left anterior descending artery occlusion and reperfusion. Blood from the great cardiac vein was sampled for the determination of adenosine and catecholamine concentrations. Hemodynamic parameters (blood pressure, lift ventricular dp/dt, left ventricular end-diastolic pressure, and cardiac output) were monitored throughout the experimental period. During coronary occlusion and reperfusion, VF occurred in 25 dogs (VF group). Ventricular fibrillation did not occur in 35 other dogs (non-VF group). Adenosine concentration in the great cardiac vein before the coronary occlusion did not differ between the two groups. However, the adenosine concentration in the great cardiac vein of the non-VF group significantly increased compared with that of the VF group (2,343 vs 65 pmol/ml, P = 0.026) during coronary occlusion and reperfusion. In contrast, hemodynamic parameters did not differ between the two groups. The study results demonstrated that adenosine concentration in the great cardiac vein was higher in the non-VF group than in the VF group, suggesting that myocardial endogenous adenosine may have a role in the suppression of ischemia and reperfusion-induced VF in dogs.

Adenosine↗
PubMed2006

Differences between men and women in terms of clinical features of ST-segment elevation acute myocardial infarction.

BACKGROUND: Many studies have examined sex-related differences in the clinical features of acute myocardial infarction (AMI). However, prospective studies are scant, and sex-related differences in symptoms of AMI remain unclear. We examined differences between men and women in terms of the clinical features of ST-segment elevation AMI. METHODS AND RESULTS: We studied 457 patients (106 women and 351 men) with ST-segment elevation AMI who were admitted within 24 h after symptom onset. The same cardiologist interviewed all patients within 48 h after admission. Women were older than men (72 vs 62 years, p<0.001) and had higher rates of hypertension (70 vs 56%, p=0.010), diabetes mellitus (36 vs 26%, p=0.047), and hyperlipidemia (51 vs 38%, p=0.019). Women were more likely than men to have non-specific symptoms (45 vs 34%, p=0.033), non-chest pain (pain in the jaw, throat, neck, shoulder, arm, hand, and back), mild pain (20 vs 7%, p<0.001), and nausea (49 vs 36%, p=0.013). On coronary angiography, the severity of coronary-artery lesions was similar in both sexes. In-hospital mortality was significantly higher in women than in men (6.6 vs 1.4%, p=0.003). CONCLUSIONS: Clinical profiles and presentations differ between women and men with AMI. Women have less typical symptoms of AMI than men.

Acute Disease↗
PubMed2006

Comparison of nifekalant and lidocaine for the treatment of shock-refractory ventricular fibrillation.

BACKGROUND: Although nifekalant is a class III antiarrhythmic agent without negative inotropic activity, its effect in patients with shock-refractory ventricular fibrillation remains unclear. METHODS AND RESULTS: Patients who had an out-of-hospital cardiac arrest with ventricular fibrillation that persisted after 3 shocks from an external defibrillator, intravenous epinephrine, and another shock were retrospectively studied. The patients received lidocaine from January 1997 through June 2001 and nifekalant from July 2001 through December 2004. Short-term survival rates (survival to hospital admission and 24-h survival) were compared between the groups. The study group comprised 120 patients (mean age: 62+/-16 years): 55 received nifekalant and 65 received lidocaine. Age, sex, history of ischemic heart disease, whether arrest was witnessed or not and time to arrival at the hospital did not differ significantly between the groups. As compared with lidocaine, nifekalant was associated with significantly higher rates of survival to hospital admission (67% vs 37%, p<0.001) and 24-h survival (53% vs 31%, p=0.01). Multivariate analysis showed that treatment with nifekalant and early initiation of cardiopulmonary resuscitation were independent predictors of 24-h survival. CONCLUSIONS: As compared with lidocaine, nifekalant may improve short-term survival in patients with out-of-hospital cardiac arrest due to shock-refractory ventricular fibrillation.

Aged↗
PubMed2006

Prognostic significance of inverted T waves in patients with acute pulmonary embolism.

BACKGROUND: The significance of inverted T waves remains unclear in patients with acute pulmonary embolism (PE). METHODS AND RESULTS: The relationship of the number of leads with inverted T waves to the severity of PE in 40 patients with acute PE was studied. Patients were classified into 3 groups according to the number of leads with inverted T waves on the admission electrocardiogram (ECG): 15 patients, or=7 leads (group H). In groups L, M and H, the rates of right ventricular dysfunction on echocardiography were 47%, 92% and 100% (p<0.01), respectively, and the rates of in-hospital complicated events (including death or the need for catecholamine support, cardiopulmonary resuscitation or mechanical cardiovascular support because of hemodynamic instability) were 0%, 8% and 46% (p=0.004), respectively. On multivariate analysis, arterial hypotension at presentation (odds ratio (OR) 8.96, p=0.049) and inverted T waves in >or=7 leads on the admission ECG (OR 16.8, p=0.037) were the only independent predictors of in-hospital complicated events. CONCLUSIONS: The number of leads with inverted T waves may be a useful and simple marker of increased risk for early complications in patients with acute PE.

Acute Disease↗
PubMed2005

Predictors of left main or three-vessel disease in patients who have acute coronary syndromes with non-ST-segment elevation.

To identify an early, simple, noninvasive predictor of left main (LM) or 3-vessel disease (3-VD), we retrospectively studied clinical variables on admission in 310 patients with acute coronary syndromes with non-ST-segment elevation. Univariate analysis indicated that many factors were related to LM/3-VD. Multivariate analysis showed that ST-segment elevation in lead aVR of >/=0.5 mm was the strongest predictor of LM/3-VD, followed by positive troponin T (odds ratio 19.7, p <0.001, and odds ratio 3.08, p = 0.048, respectively). ST-segment elevation in lead aVR of >/=0.5 mm and positive troponin T identified LM/3-VD with sensitivities of 78% and 62%, specificities of 86% and 59%, positive predictive values of 57% and 26%, and negative predictive values of 95% and 87%, respectively (p <0.05). Our findings suggest that in patients with non-ST-segment elevation acute coronary syndromes, ST-segment elevation in lead aVR of >/=0.5 mm and positive troponin T on admission (especially the former) are useful predictors of LM/3-VD.

Adult↗
PubMed2005

ST-segment depression in lead aVR: a useful predictor of impaired myocardial reperfusion in patients with inferior acute myocardial infarction.

STUDY OBJECTIVE: During inferior acute myocardial infarction (AMI), the ECG lead aVR is frequently ignored, and therefore its clinical significance remains unclear. We examined the relation between ST-segment deviation seen in lead aVR on ECGs obtained at hospital admission and myocardial reperfusion in patients who have experienced recanalized inferior AMIs. DESIGN AND SETTING: Retrospective study. PATIENTS: A total of 225 patients with inferior AMIs in whom Thrombolysis in Myocardial Infarction grade 3 flow was achieved within 6 h after symptom onset. MEASUREMENTS AND RESULTS: Patients were classified as follows according to ST-segment deviation in lead aVR on an ECG obtained at hospital admission: group A, 103 patients with no ST-segment depression; group B, 80 patients with ST-segment depression of < or = 1.0 mm; and group C, 42 patients with ST-segment depression of > 1.0 mm. There were no differences in time from symptom onset to hospital admission or in the culprit lesion among the three groups. The degree of ST-segment elevation in leads II, III, aVF, V5, or V6, the degree of ST-segment depression in leads V1 to V4, and the sum of ST-segment deviation in these leads were lowest in group A and highest in group C. In groups A, B, and C, the incidence of impaired myocardial reperfusion, defined as myocardial blush grade 0/1, was 2%, 23%, and 67%, respectively (p < 0.001). The sensitivity and negative predictive values of ST-segment depression in lead aVR for impaired myocardial reperfusion were higher than those based on other ECG variables. Multivariate analysis showed that the degree of ST-segment depression in lead aVR was an independent predictor of impaired myocardial reperfusion (odds ratio 8.41; 95% confidence interval, 2.96 to 23.9; p < 0.001). CONCLUSIONS: We conclude that the degree of ST-segment depression in lead aVR is a useful predictor of impaired myocardial reperfusion in patients who have experienced inferior AMIs.

Electrocardiography↗
PubMed2004

Clinical usefulness of ECG-gated 18F-FDG PET combined with 99mTC-MIBI gated SPECT for evaluating myocardial viability and function.

OBJECTIVES: This study sought to evaluate an imaging approach using gated 99mTc-MIBI (MIBI) SPECT and gated 18F-FDG (FDG) PET for assessment of myocardial viability and cardiac function. METHODS: Forty-eight patients (38 men, mean age 68.1 +/- 9.6 years) underwent ECG-gated FDG PET and MIBI SPECT within a week. The baseline diagnoses were coronary artery disease (31), mitral regurgitation (1), paroxysmal arrhythmia (10), and dilated cardiomyopathy (6). The gated FDG PET data were analyzed using pFAST software, and the gated MIBI SPECT data were analyzed using QGS software. Fifteen patients were diagnosed with myocardial infarction, and follow-up study was performed to assess the functional outcome four months later. An improvement in LVEF of >5% was defined as significant. The LV myocardium was divided into 17 segments, and regional defect scores were visually assessed using a 4-point scale for each segment (0 = normal, 1 = mildly reduced, 2 = moderately reduced, 3 = absent). A segment with a greater defect score on MIBI SPECT than on FDG PET was defined as a mismatch. The patients were divided into two groups: those with at least two mismatched segments (MM-group), and those with none or one (M-group). RESULTS: LVEF, EDV and ESV measured by gated FDG PET were highly correlated with those obtained by gated MIBI SPECT (r = 0.848, 0.855 and 0.911, p < 0.0001, respectively). The mean values of LVEF did not differ significantly, but EDV and ESV obtained by gated FDG PET were significantly grater than those obtained by gated MIBI SPECT (p < 0.0001). In 15 patients diagnosed with myocardial infarction, a significant association (p < 0.05) was found between the relative uptake of FDG PET and MIBI SPECT and the functional outcome 4 months later. Global LV function improved in 6 of the 8 patients showing mismatch but in only 1 of the 7 patients with matched defects, resulting in a sensitivity of 86% and specificity of 75%. The overall accuracy to predict global functional outcome was high (80%). CONCLUSION: This imaging approach allows accurate evaluation of myocardial viability. Furthermore, the high correlations of gated FDG PET and gated MIBI SPECT measurements hold promise for the assessment of left ventricular function using gated FDG PET.

Aged↗
PubMed2004

Double-counting of intracardiac electrogram during biatrial pacing.

BACKGROUND: Biatrial pacing has a significant problem with memory function that misinterprets normal sinus rhythm as atrial tachyarrhythmias and in addition estimation of the atrial pacing thresholds (biatrial and uniatrial pacing thresholds) is sometimes difficult because of small P waves. METHODS AND RESULTS: The intracardiac electrograms recorded by a pacemaker in 10 patients (age, 66.7+/-10.7 (SD) years) with implanted biatrial pacemakers were analyzed. Atrial sensing within the atrial refractory period after atrial pacing was counted in 6 of the 10 patients (timing of the double counting was 143+/-64 ms) when pacing failed in the left or right atrium. Atrial sensing within the atrial refractory period after atrial pacing disappeared when biatrial pacing was successfully performed. Atrial double-counts depend on interatrial conduction delay. The memory function of implanted pacemaker devices misinterpreted normal sinus rhythm as atrial tachyarrhythmias because of atrial double-counts. On the other hand, the biatrial pacing threshold was easily recognized using this phenomenon. CONCLUSIONS: The memory function of pacemaker devices is unreliable because of atrial double-counting during sinus rhythm in patients with biatrial pacing. However, the biatrial pacing threshold is easily checked using this phenomenon.

Aged↗
PubMed2004

Prevalence of right bundle-branch block and right precordial ST-segment elevation (Brugada-type electrocardiogram) in Japanese children.

BACKGROUND: The prevalence of Brugada-type electrocardiogram (ECG) in schoolchildren remains unclear. This study aimed to further investigate this condition. METHODS AND RESULTS: We studied the prevalence of Brugada-type ECG in 20,387 children (10,434 males and 9,953 females, 9.7 +/- 3.2 [SD] years old) during a school health examination in Kanagawa Prefecture, Japan, in 2002. We considered right bundle-branch block and ST-segment elevation of the J point of > or =0.1 mV in leads V1 through V3 as Brugada-like ECG, and an ECG was considered to be Brugada-type when the 12-lead ECG fully meet the criteria for the Brugada syndrome as recently published in a consensus report. Only 2 children (0.0098%, 95% confidence interval (CI): 0 to 0.023%) completely conformed to the criteria for Brugada-type ECG. Brugada-like ECG was found in 11 (10 male) of 20,387 children (0.054%, 95% CI: 0.022 to 0.086%). The prevalence in males was significantly higher than that in females, even in children (0.096% vs 0.010%, p=0.012). Stratified according to age, there was tendency for the prevalence of Brugada-like ECG to increase up to puberty (first graders, 0.01%; fourth graders, 0.05%; seventh graders, 0.08%; tenth graders, 0.23%; p=0.068). CONCLUSION: The prevalence of Brugada-type ECG in Japanese children was much lower than that reported in the adult population.

Adolescent↗
PubMed2003

Ischemic preconditioning prevents ischemia-induced beta-adrenergic receptor sequestration.

Preconditioning enables endogenous protection to repeated myocardial ischemia. However, the effect of preconditioning on beta1 adrenergic receptor (AR) signal remains controversial. We have recently developed receptor assay system using whole cells, in which overexpressed cell surface beta ARs can be readily quantitated without disrupting the cell. Using this technique, we examined the effects of chemical/metabolic ischemia on the beta1 AR sequestration and adenylyl cyclase activity. Isoproterenol treatment, but not forskolin treatment, of HEK293T cells overexpressing beta1 ARs led to a rapid decrease (within 2 hours) in the number of the cell surface receptor, which was negated in the presence of concanavalin A. Similarly, treatment of cells with potassium cyanide and 2-deoxy-D-glucose (chemical/metabolic ischemia) induced similar receptor sequestration. When isoproterenol was superimposed on chemical/metabolic ischemia, the degree of sequestration became greater. However, when cells were pre-exposed to potassium cyanide on the preceding day (chemical preconditioning), the sequestration induced by either isoproterenol or chemical/metabolic ischemia was attenuated. Adenylyl cyclase catalytic activity as assessed by stimulation with forskolin was decreased by chemical/metabolic ischemia but fully recovered after 24 hours, suggesting that chemical/metabolic ischemia treatment did not alter cell viability. Putting together, chemical/metabolic ischemia induced beta1 AR sequestration in a similar manner to isoproterenol. In addition, preconditioning prevented the beta1 AR sequestration induced by both isoproterenol and chemical/metabolic ischemia. Pre-conditioning may play a role in preserving the cell surface beta ARs by inhibiting the sequestration that is usually induced by an ischemic event or beta adrenergic stimulation.

Adenylyl Cyclases↗
PubMed2003

Polymorphism of the type 6 adenylyl cyclase gene and cardiac hypertrophy.

We investigated whether polymorphism of the type 6 adenylyl cyclase gene influences the occurrence of left ventricular hypertrophy in a Japanese population. Type 6 adenylyl cyclase is a major cardiac adenylyl cyclase isoform and plays an important role in regulating cardiac function. We examined the type 6 adenylyl cyclase gene for single nucleotide polymorphism by heteroduplex analysis and found a mutation (T11215A) in intron 17. We genotyped the single nucleotide polymorphism (TT/TA/AA groups) by the mutagenically separated polymerase chain reaction method in 2068 subjects who underwent health screening for cardiovascular disease. Genetic variation was in the Hardy-Weinberg equilibrium. We found no significant association between the frequency of left ventricular hypertrophy and any of the genotype groups. In the TT and the TA genotype group, however, left ventricular hypertrophy was associated with increased blood pressure, while no association with increased blood pressure was found in the AA genotype group. It was concluded that the AA group may be at risk of developing left ventricular hypertrophy independent of increased blood pressure.

Adenylyl Cyclases↗
PubMed2003

Characterization of beta-adrenergic receptor sequestration by newly developed whole cell binding assays.

Upon agonist binding, beta-adrenergic receptors sequestrate from the cell surface plasma membrane to cytosol. In the present study, we examine the kinetics of sequestration of beta1-adrenergic receptor and beta3-adrenergic receptor subtypes by radioligand binding assays using whole cells ('whole cell binding assays'). We found that HEK293T cells, but not COS1 cells, were readily and uniformly detached from the culture dish upon exposure to ice-cold phosphate-buffered saline. Using this property of HEK293T cells, we conducted whole cell binding assays using a hydrophilic antagonist ([3H]CGP-12177) and HEK293T cells transiently overexpressing human beta1-adrenergic receptor or beta3-adrenergic receptor. The Bmax and Kd values were 5.96 +/- 0.97 pmol/mg protein and 1 +/- 0.23 nM for the beta1-adrenergic receptor, and were 1.84 +/- 0.13 pmol/mg protein and 44.7 +/- 2.5 nM for the beta3-adrenergic receptor, respectively. Isoproterenol treatment, but not 6-[3-(dimethylamino)propionyl]forskolin treatment, for 2 h resulted in a dose-dependent loss of the number of the cell surface beta1-adrenergic receptor. At 100 microM, 36.6 +/- 5.7% of the cell surface beta1-adrenergic receptor was lost. In contrast, the cell surface beta3-adrenergic receptor number remained unchanged with isoproterenol treatment. Thus, beta1-adrenergic receptor sequestrates upon agonist stimulation but the same agonist stimulation does not induce beta3-adrenergic receptor sequestration, as demonstrated by our whole cell binding assays.

Animals↗