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Biomedical subjects

K Miyatake

Publications and source records attributed to K Miyatake.

At least 55 records · Page 3Linked to original sources
PubMed2000

Usefulness of the subendocardial myocardial velocity gradient in low-dose dobutamine stress echocardiography.

The subendocardial side of myocardium makes a major contribution to left ventricular (LV) contraction and is very susceptible to ischemia. In this study we sought to quantify regional wall motion during low-dose dobutamine stress echocardiography (DSE) by using the myocardial velocity gradient (MVG) derived from tissue Doppler imaging (TDI). We then compared the usefulness of subendocardial MVG with that of transmural MVG in detecting subtle wall motion abnormalities. Fourteen patients (single vessel disease = 6; normal coronary arteries = 8) underwent low-dose DSE (10 microg/ kg per min). M-Mode TDI of the LV posterior wall was recorded using a Toshiba SSA-380A combined with custom computer software, and analyzed for both subendocardial and transmural MVG. Visual estimation and transmural MVG failed to clearly demonstrate the differing responses between the nonischemic (systole: 3.0 +/- 0.8/s to 4.9 +/- 1.9/s, not significant; diastole: -4.3 +/- 1.3/s to -5.7 +/- 1.4/s, not significant; mean +/- SD, P versus ischemic segments) and ischemic (systole: 3.3 +/- 1.2/s to 3.8 +/- 1.0/s; diastole: -5.4 +/- 2.0/s to -5.3 +/- 1.1/s) segments during low-dose DSE. Subendocardial MVG demonstrated a significant change in the nonischemic segments (systole: 4.1 +/- 1.0/s to 7.7 +/- 2.2/s, P = 0.012; diastole: -6.5 +/-1.8/s to -11.3 +/- 2.2/s, P = 0.001), whereas the response remained unchanged in the ischemic segments (systole: 4.6 +/-2.4/s to 4.8 +/- 1.2/s; diastole: -7.0 +/- 1.9/s to -7.3 +/- 1.1/s). Subendocardial MVG, particularly diastolic subendocardial MVG, may serve as a useful indicator of subtle ischemic changes in wall motion induced by low-dose DSE.

Aged↗
PubMed2000

Early changes in left ventricular function in chronic asymptomatic alcoholics: relation to the duration of heavy drinking.

OBJECTIVES: This study sought to assess preclinical cardiac abnormalities in chronic alcoholic patients and possible differences among alcoholics related to the duration of heavy drinking. BACKGROUND: Chronic excessive alcohol intake has been reported as a possible cause of dilated cardiomyopathy. However, before the appearance of severe cardiac dysfunction, subtle signs of cardiac abnormalities may be identified. METHODS: We studied 30 healthy subjects (age 44 +/- 8 years) and 89 asymptomatic alcoholics (age 45 +/- 8 years, p = NS) divided into three groups, with short (S, 5-9 years, n = 31), intermediate (I, 10-15 years, n = 31) and long (L, 16-28 years, n = 27) duration of alcoholism. Transmitral early (E) and late (A) Doppler flow velocities, E/A ratio, deceleration time of E (DT) and isovolumic relaxation time (IVRT) were obtained. Left ventricular (LV) wall thickness and volumes were also determined by echocardiography, and LV mass and ejection fraction (EF) were calculated. RESULTS: The alcoholics had prolonged IVRT (92 +/- 11 vs. 83 +/- 7 ms, p < 0.001), longer DT (180 +/- 20 vs. 170 +/- 10 ms, p < 0.01), smaller E/A (1.25 +/- 0.34 vs. 1.40 +/- 0.32, p < 0.05), larger LV volumes (73 +/- 8 vs. 65 +/- 7 ml/m2, p < 0.001 for end-diastolic volume index; 25 +/- 4 vs. 21 +/- 2 ml/m2, p < 0.001 for end-systolic volume index), higher LV mass index (92 +/- 14 vs. 78 +/- 8 g/m2, p < 0.001) and thicker posterior wall (9 +/- 1 vs. 8 +/- 1 mm, p < 0.001). Ejection fraction did not differ between the two groups (66 +/- 4 vs. 67 +/- 2%). Deceleration time of the early transmitral flow velocity was longer in groups L (187 +/- 18 ms) and I (185 +/- 16 ms) compared with group S (168 +/- 17 ms, p < 0.001 for L and I vs. S), whereas A was higher in group L compared with S (43 +/- 10 vs. 51 +/- 10 cm/s, p < 0.005). Multiple regression analysis identified duration of heavy drinking as the most important variable affecting DT and A. CONCLUSIONS: Left ventricular dilation with preserved EF and impaired LV relaxation characterized LV function in chronic asymptomatic alcoholic patients. It appeared that the progression of abnormalities in LV diastolic filling related to the duration of alcoholism.

Adult↗
PubMed2000

Morphology of vulnerable coronary plaque: insights from follow-up of patients examined by intravascular ultrasound before an acute coronary syndrome.

OBJECTIVES: To determine the morphologic features of coronary plaques associated with acute coronary syndrome, we prospectively followed patients with atherosclerotic disease identified by intravascular ultrasound (IVUS). BACKGROUND: Although clinical evaluation of the vulnerable atherosclerotic plaque is important, few data exist regarding the morphology of the vulnerable plaque in clinical settings. METHODS: We examined 114 coronary sites without significant stenosis by angiography (<50% diameter stenosis) in 106 patients. All the sites exhibited atherosclerotic lesions by IVUS. These lesions consisted of 22 concentric and 92 eccentric plaques with a percent plaque area averaging 59 +/- 12%. RESULTS: During the follow-up period of 21.8 +/- 6.4 months (range 1 to 24), 12 patients had an acute coronary event at a previously examined coronary site at an average of 4.0 +/- 3.4 months after the initial IVUS study. All the preexisting plaques related to the acute events exhibited an eccentric pattern and the mean percent plaque area was 67 +/- 9%, which was greater than plaque area in the other 90 patients without acute events (57 +/- 12%, p < 0.05). There was no statistically significant difference in lumen area between two patient groups (6.7 +/- 3.0 vs. 7.5 +/- 3.7 mm2). Among 12 coronary sites with an acute occlusion, 10 sites contained the echolucent zones, eight of these shallow and two deep, likely representing a lipid-rich core. In 90 sites without acute events, an echolucent zone in the shallow portion was seen at only four sites (p < 0.05). CONCLUSIONS: Large eccentric plaque containing an echolucent zone by IVUS can be at increased risk for instability even though the lumen area is preserved at the time of initial study. Compensatory enlargement of vessel wall due to remodeling may contribute to the relatively small degree of stenosis by angiography.

Angina Pectoris↗
PubMed2000

Improvement in left ventricular function in response to carvedilol is accompanied by attenuation of neurohumoral activation in patients with dilated cardiomyopathy.

BACKGROUND: We sought to evaluate whether improvement in ejection fraction (EF) with carvedilol therapy is accompanied by improvement in neurohumoral factors. METHODS AND RESULTS: Forty-two patients with dilated cardiomyopathy were given carvedilol for 3 to 5 months. Changes in EF, plasma atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and norepinephrine levels were determined. Iodine-123 metaiodobenzylguanidine (MIBG) images were also obtained before and after carvedilol therapy. Myocardial uptake of MIBG was calculated as the heart to mediastinal activity ratio (H/M). Storage and release of MIBG was calculated as percent myocardial MIBG washout rate (WR). We divided patients into 2 groups: 27 responders whose EF increased by more than 5% and 15 nonresponders whose EF increased by 5% or less. EF of responders increased by 15 +/- 5% and that of nonresponders by 1 +/- 4%. Although MIBG image-derived indexes of nonresponders remained unchanged, the delayed H/M (1.91 +/- 0.34 v 2.24 +/- 0.53, P < .01) and WR (49 +/- 11 v 39 +/- 9%, P < .01) of responders improved, respectively. The plasma ANP (51 +/- 50 v 27 +/- 24 pg/mL, P < .01) and BNP (194 +/- 197 v 49 +/- 62 pg/mL, P < .01) levels of responders decreased. The degree of changes in the plasma BNP level correlated with changes in EF (r = -.698, P < .01). CONCLUSION: The improvement in EF with carvedilol therapy was proved to be accompanied by an improvement in neurohumoral factors.

3-Iodobenzylguanidine↗
PubMed2000

Enhanced methods for visualizing myocardial perfusion with peripheral venous injection of levovist: application of triggered harmonic imaging and triggered harmonic power Doppler imaging techniques.

OBJECTIVES: The purpose of this study was to determine whether triggered harmonic imaging (THI) or triggered harmonic power Doppler imaging (THPDI) could obtain the myocardial contrast enhancement using peripheral venous injection of a first generation echocardiographic contrast agent, Levovist. METHODS: In a phantom model, we examined the influence of an acoustic power, harmonic filters, transmitted frequencies and focus positions of transducer on Levovist. Then fundamental, harmonic or harmonic power Doppler imaging were performed with ECG-triggered imaging in eight closed-chest dogs using bolus injection of Levovist. RESULTS: In a phantom model, the highest transmission power (Mechanical index 1.6), a medium harmonic filter and a focus position (6 cm) resulted in the best enhanced contrast in both THI and THPDI. Furthermore, higher pulse repetition frequency (5500 Hz) of harmonic power Doppler made clearer enhancement. In animal models, we could not observe the apparent myocardial contrast using triggered fundamental imaging, and the intensity of each region of interest (ROI) of myocardium had not changed significantly. However, homogeneous myocardial contrast could be obtained using THI, which was conditioned on the highest transmission power, a medium harmonic filter same as the phantom model, at a lower transmitted frequency (1.8 MHz) and a focus position, which were located in the middle portion of the left ventricle. The peak intensity of each ROI increased significantly in a gray level. Furthermore, THPDI caused emphasized myocardial contrast visually. CONCLUSIONS: These results indicate that THI and THPDI produce obvious MCE using peripheral venous injection of Levovist.

Animals↗
PubMed2000

Validity and reproducibility of echocardiographic measurement of left ventricular ejection fraction by acoustic quantification with tissue harmonic imaging technique.

The tissue harmonic imaging technique can enhance detection of the cardiac endocardial border. When combined with an acoustic quantification (AQ) method, an improvement of accuracy and reproducibility of real-time measurement of left ventricular (LV) function might be expected. However, few data exist regarding the measurement of LV function by AQ with the harmonic imaging technique. Therefore, we evaluated the validity and reproducibility of AQ measurement of LV ejection fraction with or without harmonic imaging technique. A total of 50 patients (mean age 58 +/- 10 years) who underwent left ventriculography were included in our study. The LV end-diastolic and end-systolic volumes by ventriculography were 131 +/- 52 mL and 72 +/- 43 mL, respectively, and were underestimated by both conventional (70 +/- 32 mL and 36 +/- 25 mL) and harmonic (67 +/- 30 mL and 34 +/- 22 mL) AQ obtained in the apical 4-chamber view. The calculated ejection fraction by ventriculography was 0.49 +/- 0. 11 and correlated with that by conventional AQ (0.51 +/- 0.11; y = 0. 72x + 0.152; r = 0.73). This was a marked improvement when compared with the ejection fraction by harmonic AQ (0.50 +/- 0.11; y = 0.89x + 0.065; r = 0.91). Interestingly, interobserver and intraobserver variabilities of conventional AQ, which were 15.6% and 8.6%, respectively, were much improved by harmonic AQ (8.9% and 4.5%, respectively). These results indicate the feasibility of real-time measurement of LV ejection fraction by harmonic imaging, although absolute LV volume can be underestimated even by this technique.

Aged↗
PubMed2000

[Pacemaker infection caused by Staphylococcus schleiferi].

Pacemaker infection is one of the severe complication of pacemaker implantation. We report a case of pacemaker infection caused by Staphylococcus schleiferi which is a coagulase-negative staphylococcus, and its relation with human infection is not well characterized. In 1994, a 80-year-old male presented with a pacemaker pocket infection, cutaneous inflammation but no fever 2 months after insertion of a pacemaker. S. schleiferi was isolated from the pus. The patient was given cefazolin for 5 days. One month later he was readmitted because of cutaneous inflammation and the extruded generator was removed. S. schleiferi was isolated from the generator. After the patient was treated with cefazolin for 3 weeks, four consecutive wound cultures were all negative. A new generator was inserted on the same side. One month after re-insertion, the patient again presented a cutaneous inflammation, and S. schleiferi was isolated from the pus as well as the generator and the leads on their removal. Twenty-six days later, a new pacing system was inserted on the other side. There was no further recurrence of the infection. Removal of the entire pacing system was necessary to cure the infection. We expect further information of human infections caused by S. schleiferi.

Aged↗
PubMed2000

Haemodynamic correlates and prognostic significance of serum uric acid in adult patients with Eisenmenger syndrome.

OBJECTIVE: To assess haemodynamic correlates and prognostic significance of serum uric acid in adult patients with Eisenmenger syndrome. DESIGN: Retrospective observational study. SETTING: Tertiary referral centre. PATIENTS: 94 adult patients with Eisenmenger syndrome who were diagnosed between September 1982 and July 1998. MAIN OUTCOME MEASURES: Serum uric acid was measured in all patients, together with clinical and haemodynamic variables related to mortality. RESULTS: Serum uric acid was raised in patients with Eisenmenger syndrome compared with age and sex matched control subjects (7.0 v 4.7 mg/dl, p < 0.0001) and increased in proportion to the severity of New York Heart Association functional class. Serum uric acid was positively correlated with mean pulmonary arterial pressure (r = 0.30, p = 0.0052) and total pulmonary resistance index (r = 0.55, p < 0.0001), and negatively correlated with cardiac index (r = -0.50, p < 0.0001). During a mean follow up period of 97 months, 38 patients died of cardiopulmonary causes. Among various clinical, echocardiographic, and laboratory variables, serum uric acid remained predictive in multivariate analysis. Kaplan-Meier survival curves based on median serum uric acid showed that patients with high values had a significantly worse survival rate than those with low values (log-lank test: p = 0.0014 in male patients, p = 0.0034 in female patients). CONCLUSIONS: Serum uric acid increases in proportion to haemodynamic severity in adult patients with Eisenmenger syndrome and is independently associated with long term mortality.

Adolescent↗
PubMed2000

Haemodynamic and hormonal effects of adrenomedullin in patients with pulmonary hypertension.

OBJECTIVE: To investigate whether infusion of adrenomedullin, a potent vasorelaxant peptide, has beneficial haemodynamic and hormonal effects in patients with pulmonary hypertension. PATIENTS AND DESIGN: The haemodynamic and hormonal responses to intravenous infusion of adrenomedullin (0.05 microgram/kg/min) or placebo were examined in 13 patients with precapillary pulmonary hypertension. RESULTS: Infusion of adrenomedullin produced a 44% increase in cardiac index (mean (SD) 1.8 (0.2) to 2.6 (0.3) l/min/m(2), p < 0. 05) and a 32% decrease in pulmonary vascular resistance (19.7 (1.4) to 13.4 (1.3) units, p < 0.05), with a 4% reduction in mean pulmonary arterial pressure (62 (4) to 59 (4) mm Hg, NS). Adrenomedullin also decreased mean systemic arterial pressure (81 (3) to 72 (4) mm Hg, p < 0.05) and increased heart rate (73 (4) to 79 (4) beats/min, p < 0.05). Adrenomedullin decreased plasma aldosterone (9.8 (2.5) to 7.1 (1.5) ng/dl, p < 0.05) without significant changes in plasma renin activity. Plasma atrial and brain natriuretic peptides tended to decrease with adrenomedullin, although these changes did not reach significance. The haemodynamic and hormonal variables remained unchanged during placebo infusion. CONCLUSIONS: Intravenous adrenomedullin has beneficial haemodynamic and hormonal effects in patients with precapillary pulmonary hypertension.

Adrenomedullin↗
PubMed2000

Intravascular free tissue factor pathway inhibitor is inversely correlated with HDL cholesterol and postheparin lipoprotein lipase but proportional to apolipoprotein A-II.

To elucidate the distribution and clinical implications of tissue factor pathway inhibitor (TFPI) concentrations, we measured TFPI levels consisting of preheparin free, lipoprotein-bound (Lp-bound), and endothelial cell-anchor pools in 156 patients with coronary artery disease (average age, 61.2+/-9.1 years; range, 32 to 78 years) by heparin infusion (50 IU/kg) and compared them with the preheparin TFPI levels of 229 healthy subjects (average age, 59. 6+/-9.4 years; range, 41 to 80 years). The patients had lower preheparin free TFPI and lower HDL cholesterol (HDL-C) levels than the healthy subjects with equivalent Lp-bound forms (free TFPI, 15. 9+/-6.5 versus 19.2+/-8.1 ng/mL). In a partial correlation analysis, the preheparin free TFPI levels were shown to be inversely correlated with the HDL-C concentrations in both the patients (r=-0. 454, P<0.001) and the healthy subjects (r=-0.136, P<0.05). As determined by comparison of preheparin and postheparin plasma, the patients generally showed preheparin free TFPI <10%, Lp-bound TFPI at 30%, and endothelial cell-anchor TFPI at 60%. When the patients were divided into 4 categories by their LDL cholesterol (LDL-C, 130 mg/dL) and HDL-C (40 mg/dL) levels to specify their coronary risks, the low-HDL-C groups had significantly increased preheparin and postheparin free TFPI levels and decreased postheparin LPL levels, whereas the high-LDL-C groups showed increased levels of Lp-bound TFPI. In a partial correlation analysis, we found a proportional relation between postheparin free TFPI and apolipoprotein A-II (r=0. 5327) and between HDL-C and LPL (r=0.4906), whereas postheparin free TFPI was inversely correlated with HDL-C (r=-0.4280) and postheparin LPL (r=-0.4791). The inverse relationship between TFPI and LPL suggests that increased free TFPI concentrations as a compensatory response of the endothelium to prevent atherothrombotic processes compete with and displace LPL on endothelial surface, resulting in reduced LPL and low HDL-C.

Adult↗
PubMed2000

Clinical correlates and prognostic significance of six-minute walk test in patients with primary pulmonary hypertension. Comparison with cardiopulmonary exercise testing.

The six-minute walk test is a submaximal exercise test that can be performed even by a patient with heart failure not tolerating maximal exercise testing. To elucidate the clinical significance and prognostic value of the six-minute walk test in patients with primary pulmonary hypertension (PPH), we sought (1) to assess the relation between distance walked during the six-minute walk test and exercise capacity determined by maximal cardiopulmonary exercise testing, and (2) to investigate the prognostic value of the six-minute walk test in comparison with other noninvasive parameters. The six-minute walk test was performed in 43 patients with PPH, together with echocardiography, right heart catheterization, and measurement of plasma epinephrine and norepinephrine. Symptom-limited cardiopulmonary exercise testing was performed in a subsample of patients (n = 27). Distance walked in 6 min was significantly shorter in patients with PPH than in age- and sex-matched healthy subjects (297 +/- 188 versus 655 +/- 91 m, p < 0. 001). The distance significantly decreased in proportion to the severity of New York Heart Association functional class. The distance walked correlated modestly with baseline cardiac output (r = 0.48, p < 0.05) and total pulmonary resistance (r = -0.49, p < 0. 05), but not significantly with mean pulmonary arterial pressure. In contrast, the distance walked correlated strongly with peak V O(2) (r = 0.70, p < 0.001), oxygen pulse (r = 0.57, p < 0.01), and V E-VCO(2) slope (r = -0.66, p < 0.001) determined by cardiopulmonary exercise testing. During a mean follow-up period of 21 +/- 16 mo, 12 patients died of cardiopulmonary causes. Among noninvasive parameters including clinical, echocardiographic, and neurohumoral parameters, only the distance walked in 6 min was independently related to mortality in PPH by multivariate analysis. Patients walking < 332 m had a significantly lower survival rate than those walking farther, assessed by Kaplan-Meier survival curves (log-rank test, p < 0.01). These results suggest that the six-minute walk test, a submaximal exercise test, reflects exercise capacity determined by maximal cardiopulmonary exercise testing in patients with PPH, and it is the distance walked in 6 min that has a strong, independent association with mortality.

Adolescent↗
PubMed2000

Cardiac transplantation under new legislation for organ transplantation in Japan: report of two cases.

During the past 2 years since new legislation for organ transplantation from brain-dead donors came into effect in Japan, 3 cardiac transplants have been carried out, 2 of which were performed at the National Cardiovascular Center (NCVC). The recipient cases were 46- and 25-year-old male patients who suffered from end-stage dilated cardiomyopathy and had been listed for cardiac transplantation in the Japan Organ Transplantation Network as status I candidates. The first patient was supported by the use of a paracorporeal air-driven left ventricular assist device of the NCVC type, and had a moderate degree of renal and hepatic dysfunction at the time of transplantation. Donor hearts were transported from distant hospitals (Tokyo and Miyagi prefecture) and the transportation time was 1 h 33 min and 2h 4 min, respectively. The operation was performed by the standard technique (Lower-Shumway) in the first patient and by the bicaval anastomosis technique in the second patient. Reperfusion of the transplanted heart was performed retrogradely through the coronary sinus utilizing leukocyte-depleted blood with a gradual increase in temperature. Total ischemic time was 3 h 34 min and 3 h 35 min, respectively. Weaning from the cardiopulmonary bypass was easy and uneventful in each patient. Immunosuppressive therapy was conducted with OKT-3 induction in the first patient because of the coexisting renal dysfunction and with a triple immunosuppressive regimen for both patients. Routine endomyocardial biopsy showed acute rejection of less than grade Ib, and the patients were discharged on the 65th and 46th postoperative day, respectively. At present, both patients are in the NYHA class I state and are ready to return to work. The uneventful recovery seen in these patients shows the advances made in transplant medicine, including the progress and improvement of immunosuppressive therapy, surgical techniques, myocardial protection, and detection and treatment of infection. Further efforts are required to fully establish the cardiac transplantation program in Japan.

Adult↗
PubMed2000

Improvement in cardiac function and free fatty acid metabolism in a case of dilated cardiomyopathy with CD36 deficiency.

A 27-year-old man diagnosed as having dilated cardiomyopathy (DCM) without myocardial accumulation of 123I-beta-methyl-iodophenylpentadecanoic acid, and he was found to have type I CD36 deficiency. This abnormality of cardiac free fatty acid metabolism was also confirmed by other methods: 18F-fluoro-2-deoxyglucose positron emission tomography, measurements of myocardial respiratory quotient and cardiac fatty acid uptake. Although the type I CD36 deficiency was reconfirmed after 3 months, the abnormal free fatty acid metabolism improved after carvedilol therapy and was accompanied by improved cardiac function. Apart from a cause-and-effect relationship, carvedilol can improve cardiac function and increase free fatty acid metabolism in patients with both DCM and CD36 deficiency.

Adrenergic beta-Antagonists↗
PubMed2000

Increases in gastric histidine decarboxylase activity and plasma gastrin level in streptozotocin-induced type 1 diabetic rats.

When type 1 diabetes mellitus was induced in rats by injecting streptozotocin, histidine decarboxylase expression was abnormally up-regulated in a transcriptional level, and 7 d after the injection, the enzyme activity was increased about 3-fold over the control (p < 0.05). When the diabetic rats were administered with insulin for 3 d, the increased histidine decarboxylase activity returned to a normal level in addition to normalization of the plasma glucose level. The plasma gastrin level in the fasting state was also significantly elevated in the diabetic rats, and the insulin treatment normalized the level. In the diabetic rats, fasting gastric acid output increased significantly and gastric pH was lowered. These results suggest that the gastric histidine decarboxylase activity and plasma gastrin level are increased in connection with the depletion of insulin in streptozotocin-induced diabetic rats, and gastric acid secretion is stimulated at a basal level, presumably due to increases in the concentrations of histamine and gastrin in oxyntic mucosa.

Animals↗
PubMed2000

[Echocardiography of idiopathic cardiomyopathies].

Echocardiography is useful to demonstrate cardiac abnormalities seen in idiopathic cardiomyopathies. Dilated cardiomyopathy is characterized by dilated cardiac chambers and diffusely hypokinetic wall motion. Hypertrophic cardiomyopathy is characterized by left ventricular hypertrophy with no known cause. Restrictive cardiomyopathy has diastolic failure with preserved systolic function. Echocardiography demonstrates the normal sized ventricles and the dilated atria. Recent advances in echocardiography include second harmonic imaging and tissue Doppler echocardiography. Second harmonic imaging can produce good quality images with high S/N ratio and is useful to delineate the endocardial border clearly and to show smoke-like echo in cardiac chambers. Tissue Doppler echocardiography can measure wall motion velocity. One of the potential application of this method would be to differentiate constrictive pericarditis from restrictive cardiomyopathy.

Cardiomyopathy, Dilated↗