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Biomedical subjects

Tomoaki Nakata

Publications and source records attributed to Tomoaki Nakata.

At least 19 recordsLinked to original sources
PubMed2006

Assessment of left ventricular ejection fraction using long-axis systolic function is independent of image quality: a study of tissue Doppler imaging and m-mode echocardiography.

BACKGROUND: Quantitative assessment of left ventricular ejection fraction (LVEF) is technically difficult in patients with poor image quality (IQ). Mitral annulus velocity assessed by pulsed tissue Doppler imaging (TDI) and mitral annulus motion assessed by M-mode echocardiography has been shown to correlate with LVEF. Furthermore, mitral annulus sites are easy to identify even in patients with poor IQ. The purpose of this study was to determine whether these methods are useful for estimating LVEF in patients with poor IQ. METHODS: One hundred ten patients underwent TDI and M-mode echocardiography simultaneously. Mitral annulus velocity and mitral annulus motion were obtained from each of the four mitral annulus sites. Mean mitral annular peak systolic velocities (Sm) and mean mitral annular motions (MAM) were calculated by averaging at each site. IQ was defined according to a previous report. RESULTS: Both Sm and MAM were successfully measured in all patients. Mean Sm and mean MAM correlated with LVEF. These correlations were observed not only in patients with good IQ (p < 0.001, r = 0.61 for mean Sm; p < 0.001, r = 0.61 for mean MAM) or fair IQ (p < 0.001, r = 0.58 for mean Sm; p < 0.001, r = 0.68 for mean MAM) but also in patients with poor IQ (p < 0.05, r = 0.42 for mean Sm, p < 0.001, r = 0.61 for mean MAM). Using optimal cutoff values of mean Sm and mean MAM in each IQ group, sensitivity and specificity for identifying LVEF < 50% were comparable among three IQ groups. CONCLUSIONS: Assessment of long-axis systolic function by TDI and M-mode echocardiography enables estimation of LVEF even in patients with poor IQ.

Aged↗
PubMed2006

Persistent insulin-sensitizing effects of sarpogrelate hydrochloride, a serotonin 2A receptor antagonist, in patients with peripheral arterial disease.

BACKGROUND: There is considerable interest in the pleiotropic pharmacological action of sarpogrelate hydrochloride, a novel selective serotonin 2A receptor antagonist. In the present study the persistent insulin-sensitizing effects of sarpogrelate were investigated in non-diabetic and non-medicated diabetic patients with peripheral artery disease (PAD). METHODS AND RESULTS: Indices of insulin resistance (IR) (fasting immunoreactive insulin (IRI) and calculated homeostasis model assessment (HOMA-R)) and adiponectin were measured before and after 2 weeks of sarpogrelate administration (300 mg/day) in 24 patients (19 men, 76+/-9 years) with PAD. Sixteen of the 24 patients were examined after 3 months of treatment for assessment of the chronic effect of sarpogrelate on IR. After 2 weeks of treatment, significant decreases in fasting IRI (p=0.03) and HOMA-R (p=0.024), but not in adiponectin, were observed. After 3 months of treatment, significant decreases in fasting IRI (16.0+/-10.3 vs 9.2+/-2.0 microU/ml, p=0.03) and HOMA-R (4.30+/-2.83 vs 2.40+/-0.74, p=0.025) were maintained. Furthermore, adiponectin was significantly increased (8.11+/-4.13 vs 9.64+/-4.37 microg/ml, p=0.027). All of the examined HOMA-R had a significant correlation with all of the examined adiponectin (p<0.001, r=-0.441). CONCLUSIONS: Sarpogrelate has a persistent insulin-sensitizing effect through adiponectin modification and might be beneficial for anti-atherosclerotic therapy, at least, in non-diabetic and non-medicated diabetic patients with PAD.

Adiponectin↗
PubMed2006

Serial alterations and prognostic implications of myocardial perfusion and fatty acid metabolism in patients with acute myocardial infarction.

BACKGROUND: Impaired fatty acid metabolism the myocardial infarction (MI)-related area has prognostic value, but can alter over time. The aim of this study was to correlate alterations in myocardial fatty acid uptake and perfusion assessed by serial imaging with future outcomes in post-MI patients. METHODS AND RESULTS: Following 2 imaging procedures using 15-4-iodophenyl-3-(R,S)-methylpentadecanoic acid (BMIPP) and perfusion tracers at an 11-month interval, 97 patients with acute MI were followed up for 33 months with respect to the primary endpoints of death, non-fatal MI and heart failure. Regional tracer uptake was semi-quantified for both the MI-related and remote coronary territories. A large BMIPP defect relative to a perfusion defect appeared on MI-related coronary territories. Thirteen patients with cardiac events had a greater prevalence of large BMIPP and perfusion defect scores for the MI-related areas on the first scan, previous MI, diabetes mellitus, and worsening of perfusion tracer uptake in the MI-related area than those without cardiac events. Multivariate analysis identified worsening perfusion in the MI-related area on the second scan, a large BMIPP defect in the same area on the first scan and previous MI as significant predictors with chi-square values of 3.48, 6.41 and 6.84, respectively. A combination of 3 predictors significantly (p<0.05) increased the global chi-square value to 15.45 compared with each chi-square value. CONCLUSIONS: The size of the infarct-related risk area assessed by early cardiac BMIPP imaging and deterioration of perfusion tracer uptake in the compromised area for the first 12 months following acute MI are related to future cardiac events, indicating a rationale for identifying metabolically damaged but viable myocardium for further risk stratification of post-MI patients.

Acute Disease↗
PubMed2006

Early positive biomarker in relation to myocardial necrosis and impaired fatty acid metabolism in patients presenting with acute chest pain at an emergency room.

BACKGROUND: Measurement of circulating biomarkers has enabled early diagnosis and risk assessment of acute coronary syndrome. This study sought diagnostic values of the first single-point data of biomarkers obtained soon after patient arrival by comparing with scintigraphically quantified myocardial injury in patients presenting with acute chest pain at an emergency room. METHODS AND RESULTS: Serial blood samples were taken soon after arrival in an emergency department in 74 patients with suspected acute coronary syndrome to quantify blood levels of troponin-T (TnT), heart-type fatty acid-binding protein (H-FABP), myocardial-bound creatine kinase (CK-MB), and myoglobin. Myocardial perfusion and metabolic defects were scintigraphically quantified. The first single-point data had high positive predictive values for detecting the defects (80-100%) but low negative predictive values (15-41%). CK-MB and TnT had higher specificities (73-100%) but significantly lower positive rates (22-27%) than the others (61-68%), resulting in greater sensitivities of H-FABP and myoglobin (75-80%) than those of CK-MB and TnT (29-35%). Among biomarkers, TnT peak concentrations most closely correlated with scintigraphic abnormalities. CONCLUSION: H-FABP can contribute to early detection of myocardial injury and TnT is most likely to correlate with injured myocardial mass. The differential features of biomarkers are complementary in patients with acute chest pain presenting at an emergency room.

Acute Disease↗
PubMed2005

Strain rate imaging for noninvasive functional quantification of the left atrium: comparative studies in controls and patients with atrial fibrillation.

Strain rate (SR) imaging enables quantitative measurement of left ventricular (LV) function independent of cardiac translation. However, whether SR imaging is applicable for detection of left atrial (LA) dysfunction remains unknown. The purpose of this study was to assess the feasibility of measuring LA function by SR imaging, focusing on the effects of aging and LA dilatation during atrial fibrillation (AF). Echocardiographic evaluation including SR imaging was performed in 50 controls (29 males and 21 females; mean age, 41 +/- 14 years) and in 27 patients with AF (15 males and 12 females; mean age, 62 +/- 12 years; 8 with persistent AF and 19 with paroxysmal AF) from 3 apical views and analyzed off-line. Peak SR was measured at each LA segment (septum, lateral, posterior, anterior, and inferior), and mean peak systolic SR (SR-LAs), early diastolic SR (SR-LAe), and late diastolic SR (SR-LAa) were calculated by averaging the results for each segment. LA dimension, peak mitral and pulmonary velocities at late diastole, LA fractional shortening, and atrial filling fraction were calculated as parameters of LA function. Normal values for mean SR-LAs, SR-LAe, and SR-LAa were 3.4 +/- 1.0 s -1 , -3.9 +/- 1.7 s -1 , and -3.1 +/- 1.0 s -1 , respectively, and they were successfully measured in more than 95% of the LA segments. In controls, both mean SR-LAs and mean SR-LAe correlated with age, LA dimension, and early to late diastolic mitral flow velocity ratio. Conversely, mean SR-LAa did not show significant correlation with age or parameters of LA function. In AF patients, mean SR-LAs was correlated inversely with age. The mean SR-LAs was significantly lower in persistent AF patients than in age-matched controls (1.7 +/- 0.8 vs 2.9 +/- 0.9 s -1 ; P < .01). Based on our findings, we conclude that noninvasive quantification of LA function using SR imaging enables evaluation of LA dysfunction due to aging and LA dilatation.

Adult↗
PubMed2004

Cardiac metaiodobenzylguanidine activity can predict the long-term efficacy of angiotensin-converting enzyme inhibitors and/or beta-adrenoceptor blockers in patients with heart failure.

PURPOSE: Although the benefits of treatment with angiotensin-converting enzyme (ACE) inhibitors and beta-blockers are well known, no method has as yet been established to predict the efficacy of drug therapy. This study tested whether cardiac 123I-metaiodobenzylguanidine (MIBG) activity is of prognostic value and can predict the improvement in heart failure patients resulting from treatment with ACE inhibitors and/or beta-blockers. METHODS: Following quantification of the heart-to-mediastinum ratio (HMR) of MIBG activity, 88 patients with heart failure who were treated with ACE inhibitors and/or beta-blockers (treated group) and 79 patients with heart failure who were treated conventionally without the aforementioned agents, and who served as controls, were followed up for 43 months with a primary endpoint of cardiac death. RESULTS: The treated group had a significantly lower prevalence of cardiac death and a significantly lower mortality at 5 years compared with the control group (15% vs 37% and 21% vs 42%, p<0.05, respectively). Multivariate analysis revealed that significant predictors were HMR, age, nitrate use and ventricular tachycardia for the treated group, and HMR, nitrate use and NYHA class for the control group. The drug treatment significantly reduced mortality from 36% to 12% when HMR was 1.53 or more and from 53% to 37% when HMR was less than 1.53. The reduction in risk of mortality within 5 years in patients without a severe MIBG defect (67%) was twice that in patients with such a defect (32%) (p<0.05). CONCLUSION: The reduction in mortality risk achieved by using ACE inhibitors and/or beta-blockers is associated with the severity of impairment of cardiac MIBG uptake. Cardiac MIBG activity can consequently be of long-term prognostic value in predicting the effectiveness of such treatment in patients with heart failure.

3-Iodobenzylguanidine↗
PubMed2004

Prognostic value of fatty acid imaging in patients with angina pectoris without prior myocardial infarction: comparison with stress thallium imaging.

A fatty acid analogue, 123I-labelled beta-methyl iodophenyl pentadecanoic acid (BMIPP), has been used to identify ischaemic and metabolically impaired myocardium. However, the prognostic value of BMIPP imaging, particularly in relation to stress myocardial perfusion imaging, remains unclear. Data from 167 consecutive patients with angina pectoris but without prior myocardial infarction (MI) who had undergone both BMIPP and stress 201Tl (sTL) imaging were analysed. Tracer uptake was graded using a 13-segment, 4-point scoring model. Patients were followed up for 48 months with primary end points (cardiac death, non-fatal MI) as hard cardiac events and with secondary end points (late revascularisation, recurrent angina and heart failure) as soft events. For overall cardiac events (5 hard and 29 soft events), Kaplan-Meier analysis revealed significantly lower event rates in subgroups with normal BMIPP uptake, a summed difference score of sTL (SDS) of <3 or absence of diabetes mellitus when compared to each counterpart. Multivariate Cox's analysis revealed reduced BMIPP uptake, SDS > or =3, diabetes and reduced ejection fraction to be significant predictors. Negative predictive values of normal BMIPP and SDS <3 for all events were 91% and 84%, respectively. No hard event occurred in 66 patients with normal BMIPP uptake, whereas two patients with SDS <3 but impaired BMIPP uptake had hard events. In conclusion, normal BMIPP imaging is an excellent prognostic sign, independently of stress myocardial perfusion imaging, in patients with angina pectoris without prior MI.

Adult↗
PubMed2004

Utility of serum ratio of heart-type fatty acid-binding protein to myoglobin for cardiac damage regardless of renal dysfunction.

BACKGROUND: The serum ratio of heart-type fatty acid-binding protein to myoglobin (F/M) has been shown to be a new marker for cardiac damage and volume overload in hemodialysis patients. We evaluated the utility of F/M in hemodialysis patients compared to control subjects. METHODS AND RESULTS: Twenty-one hemodialysis patients and 17 control subjects with normal renal function were investigated. Using a cutoff point of mean + 2SD of the F/M in the controls (value: 0.147), the hemodialysis patients were divided into 2 groups. The concentrations of atrial natriuretic peptide (ANP) and brain natriuretic peptide after hemodialysis in the high F/M group were higher than those in the low F/M group. The mean level of ANP in the low F/M group was almost the upper limit of normal range. The values of left ventricular end-diastolic dimension and left ventricular mass index in the high F/M group were higher than those in the low F/M group, and the mean levels of those in the low F/M group were almost the same as those in the controls. CONCLUSIONS: The F/M can be evaluated by the absolute value regardless of renal dysfunction, and the value of 0.147 might be useful for determining the cutoff level of cardiac involvement.

Aged↗
PubMed2004

Incremental prognostic implications of brain natriuretic peptide, cardiac sympathetic nerve innervation, and noncardiac disorders in patients with heart failure.

UNLABELLED: Plasma brain natriuretic peptide (BNP) level and cardiac autonomic function are closely related to prognosis in patients with heart failure. However, their correlation and incremental prognostic values in human heart failure are unclear. We sought to evaluate the correlation between BNP level and cardiac sympathetic innervation assessed by (123)I-metaiodobenzylguanidine ((123)I-MIBG) and the prognostic value of combined assessment of risk factors for mortality in patients with heart failure. METHODS: After conventional examinations and measurements of plasma BNP level and heart-to-mediastinum ratio (HMR) of cardiac (123)I-MIBG activity, 158 patients with heart failure were prospectively followed with an endpoint of cardiac death for 16 mo. RESULTS: Fifteen deaths due to pump failure and 2 sudden cardiac deaths were documented. Plasma BNP level correlated with HMR significantly but not so tightly (r = 0.330, P < 0.0001). Univariate analysis identified plasma BNP level, HMR, chronic renal dysfunction, diabetes mellitus, age, and use of nitrates as significant predictors of fatal pump failure, and multivariate Cox analysis showed that plasma BNP level was the most powerful predictor of cardiac death. Patients with both plasma BNP level of > or = 172 pg/mL and late HMR of < or =1.74 had a greater annual rate of fatal pump failure than did those without (17.5%/y vs. 0%-3.9%/y, respectively). The hazard ratio of plasma BNP level (7.2) or cardiac (123)I-MIBG activity (10.1) increased to 34.4 when both variables were used, and prevalence of fatal pump failure significantly increased from 22% to 62.5% when diabetes mellitus and chronic renal dysfunction were present with a higher plasma BNP level and low cardiac (123)I-MIBG activity. CONCLUSION: Plasma BNP level is a stronger predictor than other risk factors for mortality in heart failure patients and is statistically significantly, but roughly, related to cardiac sympathetic nerve innervation. Impaired cardiac sympathetic nerve innervation and the presence of diabetes mellitus and chronic renal dysfunction, however, improve risk stratification of patients with heart failure and increased plasma BNP concentration.

3-Iodobenzylguanidine↗
PubMed2003

Prognostic implications of an initial loss of cardiac metaiodobenzylguanidine uptake and diabetes mellitus in patients with left ventricular dysfunction.

BACKGROUND: Although altered cardiac sympathetic innervation is related to fatal outcome, the mechanisms and prognostic value of an initial cardiac metaiodobenzylguanidine (MIBG) defect are not known. METHODS AND RESULTS: After quantitative cardiac MIBG imaging, 205 patients with left ventricular ejection fraction <50% were prospectively followed up with a primary end-point of cardiac death for 35 months. In regard to 38 cardiac deaths, consisting of 25 pump failure deaths, 11 sudden deaths, and 2 fatal acute myocardial infarctions, multivariate analysis identified diabetes mellitus as a significant independent predictor as well as reduced cardiac MIBG activity, use of nitrate, and New York Heart Association functional status. Independent of washout kinetics and cardiac function, patients with profound loss of initial MIBG uptake and those with late-phase MIBG activity of 1.74 or less had significantly greater mortality rates than did their counterparts. Initial cardiac MIBG activity closely correlated inversely with annual cardiac death rate. CONCLUSIONS: An initial cardiac MIBG defect and presence of diabetes mellitus indicate a low probability of long-term survival. The profound loss of initial MIBG activity is likely to be due to structural deficit of sympathetic neurons themselves, rather than accelerated sympathetic function, suggesting that denervation is one of mechanisms of cardiac sympathetic dysfunction leading to lethal clinical outcomes.

3-Iodobenzylguanidine↗
PubMed2003

Serum ratio of heart-type fatty acid-binding protein to myoglobin. A novel marker of cardiac damage and volume overload in hemodialysis patients.

BACKGROUND: The concentration of heart-type fatty acid-binding protein (hFABP), a promising novel marker for detection of acute or persistent myocardial damage, is significantly influenced by renal clearance and thus has limitations to its usefulness in patients with renal dysfunction. We evaluated whether the serum ratio of hFABP to myoglobin (F/M) might be a useful marker for assessing cardiac damage in hemodialysis patients. METHODS: Serum hFABP and myoglobin were measured, and the value of F/M was calculated in 21 hemodialysis patients. Cardiac markers (cardiac troponin T [cTnT], atrial natriuretic peptide [ANP], and brain natriuretic peptide [BNP]) and echocardiographic indices (left ventricular end-diastolic dimension [LVDd], left ventricular mass index [LVMI], and inferior vena cava [IVC] dimension) were examined and compared with hFABP, myoglobin, and F/M ratios. RESULTS: Serum hFABP and myoglobin levels were significantly elevated in hemodialysis patients and reduced by 30-40% during hemodialysis. The value of F/M after hemodialysis, but not the concentration of hFABP or myoglobin, had significant linear correlations with ANP, BNP, cTnT, LVDd, LVMI, and IVC. CONCLUSION: The value of F/M after hemodialysis, but not the concentration of hFABP itself, might be a newly useful marker for estimation of cardiac damage and volume overload in hemodialysis patients.

Adult↗
PubMed2003

Human heart-type fatty acid-binding protein as an early diagnostic and prognostic marker in acute coronary syndrome.

Although heart-type fatty acid-binding protein (H-FABP) can be a marker of sarcolemmal injury due to acute myocardial ischemia, the diagnostic or prognostic value is not established in patients with acute chest pain. This multicenter prospective study aimed to determine the diagnostic and prognostic values of H-FABP in 133 patients presenting to an emergency room with suspected acute coronary syndrome (ACS) by comparing with those of conventional biomarkers. H-FABP and myoglobin had greater positive results than did creatine kinase-MB or troponin T. Receiver operating characteristics analysis revealed that H-FABP was the most reliable for detection of ACS and that H-FABP had the greatest sensitivities for identification of patients requiring emergency hospitalization, coronary angiography, and interventional therapy within 7 days among the biomarkers. Thus, H-FABP can be an early diagnostic and prognostic biochemical marker, particularly within the first 6 h from the onset of chest symptoms, in patients with chest pain at an emergency department.

Acute Disease↗
PubMed2003

Insulin sensitivity and lipid metabolism in human CD36 deficiency.

OBJECTIVE: CD36 has been proposed as a fatty acid translocase and a receptor for HDL and oxidized LDL. The association between CD36 deficiency and insulin resistance remains controversial. We investigated glucose and lipid metabolism in human CD36 deficiency. RESEARCH DESIGN AND METHODS: A total of 61 type I CD36-deficient patients and 25 control subjects were examined. Diabetes was defined as fasting glucose level > or =7 mmol/l or use of hypoglycemic agents. A homeostasis model assessment (HOMA) index was evaluated in patients without diabetes. Insulin resistance was defined as a HOMA index > or =1.73 (sensitivity 64.3%, specificity 78.9%; J Japan Diab Soc, 2000). RESULTS: Diabetes was identified in 12 (20%) of the 61 CD36-deficient patients. Fasting glucose, HbA(1c), and total cholesterol levels in the diabetic CD36-deficient patients were significantly higher than in the control subjects and the nondiabetic CD36-deficient patients. Regardless of diabetes, HDL cholesterol concentrations in the CD36-deficient patients were significantly higher than in the control subjects. The nondiabetic CD36-deficient patients had higher triglyceride concentrations than the control subjects, and triglyceride concentrations were higher in the diabetic CD36-deficient patients than in the nondiabetic CD36-deficient patients. The prevalence of insulin resistance in the nondiabetic CD36-deficient patients was similar to that in the control subjects. CONCLUSIONS: Human CD36 deficiency is not necessarily responsible for insulin resistance. Lipid abnormalities in CD36 deficiency may partly depend on the presence of diabetes, and increased levels of triglyceride and HDL cholesterol may be due to impaired binding of fatty acids and HDL to CD36 and subsequent clearance.

Aged↗
PubMed2002

Effect of intravenous propranolol on left ventricular apical ballooning without coronary artery stenosis (ampulla cardiomyopathy): three cases.

The precise etiological basis of transient left ventricular apical ballooning without coronary artery stenosis (ampulla or so-called 'takotsubo' cardiomyopathy) remains unknown, so the present study examined the acute effects of intravenous propranolol (2-4 mg) in 3 female patients (age range, 61-76 years) with the condition. Although one patient who did not have any intraventricular pressure gradients showed no improvement in the electrocardiographic and left ventricular wall motion abnormalities, the other 2 patients, who had significant intraventricular pressure gradients, did show improvement. Dynamic intraventricular obstruction might play a role in maintaining apical ballooning, at least, in patients exhibiting an intraventricular pressure gradient.

Adrenergic beta-Antagonists↗