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Biomedical subjects

Fumihiko Miyake

Publications and source records attributed to Fumihiko Miyake.

At least 19 recordsLinked to original sources
PubMed2006

Population pharmacokinetic and pharmacodynamic analysis of a class IC antiarrhythmic, pilsicainide, in patients with cardiac arrhythmias.

Population pharmacokinetics (PK) of a sodium channel-blocking antiarrhythmic, pilsicainide, was studied using the nonlinear mixed-effects modeling technique in 91 patients with cardiac arrhythmias (80 suspected Brugada syndrome [BrS] and 11 with atrial fibrillation) who received an intravenous infusion of 10 mg of the drug. Population pharmacodynamic (PD) analysis was also performed using an effect compartment model. PD responses were assessed by changes in electrocardiogram (ECG) pattern (BrS-like elevation of ST-segment) and conduction parameters. The final PK model showed that gender (values were 50% lower in women than in men) and creatinine clearance were significant (P < .01) covariates of weight-normalized systemic clearance of pilsicainide. Patients who showed a BrS-like ECG pattern after the drug administration also showed a significantly (P < .01) greater prolongation in His-Purkinje conduction compared to the remaining patients. In conclusion, female gender, renal dysfunction, and the drug-induced BrS-like ECG morphology may be associated with augmented ECG responses to pilsicainide.

Adult↗
PubMed2006

Functional capacity, skeletal muscle strength, and skeletal muscle volume in patients with myocardial infarction.

Previous studies have reported that skeletal muscle strength is closely related to exercise capacity in patients with myocardial infarction (MI). However, none of the previous studies have fully investigated the correlation between exercise capacity and the skeletal muscle volume (MV). Seventy patients with MI underwent symptom-limited cardiopulmonary exercise testing using a treadmill. The MV was evaluated by electrical impedance analysis and the maximal knee extension strength (Peak torque: PT) was measured by a Biodex. The subjects were divided into 2 groups according to the MV (group L, MV < 22 kg; group H, MV > or = 22 kg). The PT was positively and significantly correlated with the peak V(.)O(2) in both the L and H groups (r = 0.70 versus r = 0.71). The MV of the lower limbs was positively correlated with the peak V(.)O(2) in the L group (r = 0.57), but not in the H group. The lower limb MV was positively and significantly correlated with PT in the L group (r = 0.48), but not in the H group. The exercise capacity of patients with MI is thought to depend on both the strength and volume of the skeletal muscle. In MI patients with high muscle volume, exercise capacity was determined by skeletal muscle strength alone.

Electric Impedance↗
PubMed2005

Reversible ventricular dysfunction takotsubo cardiomyopathy.

BACKGROUND: Recently, many cardiologists have recognized the existence of a rapidly reversible form of heart failure of unknown origin characterized by a takotsubo-shaped, dyskinetic left ventricle on left ventriculography. AIM: To determine the detailed clinical features of takotsubo cardiomyopathy. METHODS: Thirteen elderly patients (11 women and 2 men with a mean age of 75.3 years) who had normal coronary arteries and takotsubo-like left ventricular dysfunction were prospectively enrolled in this study. RESULTS: Cardiac enzymes did not increase significantly, but the mean plasma norepinephrine level was very high on admission (0.98 microg/l). Coronary angiography revealed normal coronary arteries in all patients, but left ventriculography showed apical akinesis combined with basal hyperkinesis, i.e., a takotsubo (Japanese octopus fishing pot)-shaped ventricle. Left ventricular wall motion normalized within a mean of 16.9 hospital days in 12 patients, but 1 patient died of acute renal failure on hospital day 7. Cardiac events did not recur during a follow-up period of 0.5 to 5 years. CONCLUSION: Takotsubo cardiomyopathy seems to be a new type of acute heart failure, which generally has a good prognosis and does not recur. Myocardial damage by catecholamine overload, adrenoceptor hypersensitivity, and changes of catecholamine dynamics due to stress may cause this condition.

Aged↗
PubMed2005

Automated detection of Brugada-type electrocardiogram using diagnostic criteria of the European Society of Cardiology and the American Heart Association.

The diagnostic criteria of Brugada syndrome were reported from the European Society of Cardiology (ESC) and the American Heart Association in 2002. We examined the automated detection of Brugada-type electrocardiogram (ECG) on 12-lead ECG analysis program by modifying ESC criteria and evaluated it. In ESC criteria, Brugada-type ECG was classified into 3 types of ST-segment abnormalities of V1 to V3 leads. We modified these criteria and determined automated detection criteria as follows: type 1: STj>or=0.2 mV and STj>ST1>ST2 and T<0 mV; type 2: STj>or=0.2 mV and STj>STmin>or=0.1 mV and T>0 mV and T<1.8xR' and S or=0.2 mV and 0.1 mV>STmin>0 mV and T>0 mV and T<1.8xR' and S>or=3.0 mV; STj, ST1, and ST2 are amplitude of the ST segment (STj: J point, ST1: J point +40 milliseconds, ST2: J point +80 milliseconds). We evaluated these criteria with 97 ECGs from 27 patients, which are diagnosed as Brugada syndrome in university hospital. Brugada-type ECGs were detected correctly in 85 of total 97 ECGs (sensitivity, 88.7%, type 1: 32/32, type 2: 50/61, type 3: 4/4). As compared with 5 cardiologists interpretation of Brugada-type ECGs, computer classified incorrectly in 20 ECGs (type 1: 2, type 2: 17, type 3: 1) in 21,524 cases.

American Heart Association↗
PubMed2005

Preload-adjusted 2 wave-intensity peaks reflect simultaneous assessment of left ventricular contractility and relaxation.

BACKGROUND: The magnitudes of the first (WI1) and the second wave-intensity peak (WI2) during the ejection period can be used as indices of left ventricular (LV) contractility and relaxation, respectively. However, use of WI to characterize LV dp/dt and the end-diastolic volume (V ed) relationship may be more problematic, as WI may be affected by changes in preload. METHODS AND RESULTS: The LV pressure-volume data sets, consisting of 23 recordings obtained by the conductance method from 12 heart disease patients, were studied. End-systolic elastance (E es) and volume-axis-intercept (V0) were calculated with varying preload. Time constant of LV relaxation (tau), V ed, and WI were calculated from steady-state averaged data. The E es showed a weak correlation with WI1 (r = 0.46, p < 0.05) but a better correlation with preload-adjusted WI1 [WI1/V ed; r=0.86, WI1/V(ed)2; r = 0.92, WI1/(V ed - V0)2; r = 0.89, all p < 0.01]. Similarly, tau did not correlate with WI2 but did correlate with preload-adjusted WI2 [WI2/V ed; r = -0.73, WI2/V(ed) 2; r = -0.63, WI2/(V ed - V0)2; r = -0.78, all p < 0.01]. CONCLUSIONS: These data demonstrate the importance of preload-adjustment when using the WI index for simultaneous assessment of LV contractility and relaxation.

Diastole↗
PubMed2005

Relationship between exercise intolerance and levels of neurohormonal factors and proinflammatory cytokines in patients with stable chronic heart failure.

We investigated the correlations between exercise intolerance and the plasma levels of neurohormonal factors and proinflammatory cytokines in chronic heart failure (CHF) patients. Sixty-two CHF patients who underwent cardiopulmonary exercise testing (CPX) were enrolled in this study. Peak oxygen uptake (peak VO2) and the plasma concentrations of noradrenaline (NA), brain natriuretic peptide (BNP), and soluble tumor necrosis factor receptors I and II (TNFR-I and -II) were all measured during the CPX. The patients were divided into three groups according to their peak VO2; a severe exercise intolerance group (severe group; peak VO2 < 18 mL/min/kg), moderate exercise intolerance group (moderate group; 18 24). There were no significant differences in left ventricular ejection fraction (EF) among the three groups. NA and BNP both increased gradually in parallel with the worsening of exercise intolerance (NA, 211.5 +/- 75.7 pg/mL, 331.8 +/- 163.7, 441.9 +/- 202.9, respectively; BNP, 37.9 +/- 25.4 pg/mL, 148.9 +/- 117.1, 247.9 +/- 150.0, respectively). TNFR-I and II were significantly higher in the severe group than in the moderate group (1746.1 +/- 950.7 versus 1085.2 +/- 370.5 pg/mL and 2855.3 +/- 1550.9 versus 2047.7 +/- 648.7 pg/mL, respectively), while the values in the moderate group were not significantly different from those in the mild group. EF showed no significant correlations with NA, BNP, TNFR-I, or TNFR-II, whereas peak VO2 exhibited significant negative correlations with NA (r = -0.50, P < 0.0001), BNP (r = -0.53, P < 0.0001), TNFR-I (r = -0.50, P < 0.0001), and TNFR-II (r = -0.45, P < 0.0001). It is concluded that NA and BNP rise in parallel with the degree of exercise intolerance, while TNFR-I and -II rise only when exercise intolerance reaches severe levels.

Aged↗
PubMed2004

Clinical significance of electrocardiography recordings from a higher intercostal space for detection of the brugada sign.

BACKGROUND: The significance of higher intercostal space electrocardiography (HICS ECG) for the detection of the Brugada sign was investigated. METHODS AND RESULTS: The subjects consisted of 113 cases (108 males, 5 females; mean age, 57+/-17 years) with incomplete right bundle branch block type QRS morphology and ST-segment elevation (>0.10 mV) in the right precordial leads. Obvious structural heart disease was not observed in any of the subjects. The V(1-3) leads of the standard 12-lead ECG and the HICS ECG were recorded in the supine position, and the amplitude of the terminal portion of the QRS (J-point) and ST-segment (80 ms from the J-point) were measured. In the HICS ECG, there was an increase in the area in which the Brugada sign was detectable (47 leads to 66 leads), and in cases with the Brugada sign, the amplitude of the J-point increased. CONCLUSIONS: The HICS ECG may be helpful for the detection of the Brugada sign.

Adult↗
PubMed2004

Brugada syndrome-like ST-segment elevation increase exacerbated by vomiting.

The patient was a 53 year-old male who had 3 syncopal episodes over a 6-month period. In the electrophysiological study, ventricular fibrillation (VF) was repeatedly induced by the ventricular extrastimulus method. Intravenous pilsicainide was administered, and the J-point and ST-segment in the right precordial leads became slightly elevated just following drug administration. Five min later, the patient experienced severe nausea and then vomited twice, at which point the electrocardiogram (ECG) showed increased elevation of the J-point and ST-segment. These ECG changes recovered to normal 30 min later. The cause of his syncope was strongly suspected to be related to the VF associated with Brugada syndrome. An interesting aspect of this case was the particular type of J-point and ST-segment elevation that was induced when the patient experienced nausea and vomiting. It is proposed that this phenomenon originated from the vagal stimulation associated with the nausea and vomiting.

Acetylcholine↗
PubMed2004

New holter monitoring analysis system: a calculation of the lead vectors.

BACKGROUND: A new system of synthesizing a 12-lead electrocardiogram (Syn-ECG) with practically identical waveforms to the standard 12-lead ECG (Stn-ECG) from 3-channel ECGs recorded by Holter monitoring has been developed. METHODS AND RESULTS: The study group comprised 16 healthy individuals and 13 patients with abnormal ECGs. The bipolar eV1, eV5 and eVF leads were recorded using digital Holter monitoring and nine Syn-ECGs, corresponding to each lead of the Stn-ECG, were synthesized. The 9 ECGs consisted of a theoretical Syn-ECG and 8 Syn-ECGs positioned around the theoretical Syn-ECG at 3 cm intervals on the Frank's image surface. Of the 9 ECGs, the Syn-ECG with the maximum product of the cross-correlation coefficient of the QRS wave and that of the T wave, was automatically selected as the optimal Syn-ECG. The amplitude data from the QRS wave, R wave, T wave, and ST level, and also the amplitude ratio of the R wave, T wave to the QRS wave, were significantly well correlated between the Syn-ECG and Stn-ECG. CONCLUSIONS: A practically identical ECG morphology, comparable with a Stn-ECG, was successfully created using this system.

Adult↗
PubMed2004

Congenital absence of the left circumflex coronary artery associated with acute myocardial infarction: a case report.

Among the congenital anomalies of the coronary arteries, a left circumflex artery (LCX) defect is extremely rare. A 49-year-old man who developed an acute anterior infarction underwent coronary angiography, which revealed complete occlusion of the left main trunk, but the territory usually supplied by the LCX had been perfused by the superdominant right coronary artery. Treatment of the left main trunk by percutaneous coronary intervention produced a favorable result. Accurate evaluation of the principal vessels and the extent of compensatory perfusion is important when diagnosing ischemic heart disease accompanied by anomalous coronary arteries and for choosing the best treatment modality.

Arteries↗
PubMed2004

Efficacy of steroid therapy for pacing failure in a patient with chronic myocarditis.

A 66-year-old man had a progressive increase in the pacing threshold over a one-year period, resulting from chronic myocarditis. Following steroid therapy, the pacing threshold decreased and became stabilized, and was accompanied by a decrease in the serum creatine kinase, cardiac myosin light chains and pro-collagen III peptide values, but cardiac function did not improve. Endocardial biopsy showed that there was no progression in the fibrosis. The pacing failure improved, but the cardiac function did not. It was believed that the steroid therapy suppressed the progression of the inflammation and fibrosis caused by the chronic myocarditis.

Aged↗
PubMed2004

An atypical case of "Takotsubo cardiomyopathy" during alcohol withdrawal: abnormality in the transient left ventricular wall motion and a remarkable elevation in the ST segment.

A 64-year-old man was admitted due to hypokalemia-related myopathy. He was heavy drinker. He felt the stress of alcohol withdrawal during his hospitalization. The patient suffered a cardiopulmonary arrest lasting approximately 5 minutes on the fifth hospital day. One day later, ST-segment elevation was observed in leads I, aV(L), and V(2-6). Emergent cardiac catheterization was performed for suspicion of acute myocardial infarction. Normal coronary arteries with anterior akinesis of the left ventricle were revealed during the procedure. The present case may be an atypical form of "Takotsubo cardiomyopathy" in which the left ventricular contraction is due to focal anterior wall motion abnormalities.

Cardiomyopathies↗
PubMed2004

Left ventricular rupture associated with Takotsubo cardiomyopathy.

A 70-year-old woman was admitted to the hospital with chest discomfort after quarreling with her neighbors. Electrocardiography revealed ST-segment elevation in leads I, II, III, aVL, aVF, and V2 through V6. Coronary angiography demonstrated normal arteries, but left ventriculography showed apical akinesis and basal hyperkinesis. Takotsubo cardiomyopathy was diagnosed on the basis of these characteristic findings. The creatine kinase and creatine kinase-MB concentrations were elevated at admission and reached maximum levels 6 hours after admission. The plasma level of brain natriuretic peptide was 10.7 pg/mL (reference range, <18.4 pg/mL) on the first hospital day. ST-segment elevation in leads I, II, III, aVL, aVF, and V2 through V6 persisted at 72 hours after admission. On the third hospital day, sudden rupture of the left ventricle occurred, and despite extensive resuscitation efforts, the patient died. Takotsubo cardiomyopathy presents in a manner similar to that of acute myocardial infarction, but ventricular systolic function usually returns to normal within a few weeks. To our knowledge, this is the first reported case of fatal left ventricular rupture associated with takotsubo cardiomyopathy. We suggest that takotsubo cardiomyopathy may be a newly recognized cause of sudden cardiac death.

Aged↗
PubMed2004

Relations between strength and endurance of leg skeletal muscle and cardiopulmonary exercise testing parameters in patients with chronic heart failure.

OBJECTIVES: The relations between muscle strength, muscle endurance, and cardiopulmonary parameters were investigated in patients with chronic heart failure. METHODS: The subjects comprised 33 outpatients with stable chronic heart failure (27 men, 6 women, mean age 60.3 +/- 12.7 years). A pedal-type isokinetic device was used throughout the study. The safety of the study protocol was examined first. Maximum muscle power (peak power), an index of muscle strength, was measured for 6 consecutive revolutions(3 revolutions of each leg). The strength decrement index (SDI) was measured for 20 consecutive maximal revolutions (10 revolutions in each leg). The SDI is an index of muscle endurance and compares the mean power for revolutions 9 and 10 with that for revolutions 2 and 3. Each subjects underwent symptom-limited cardiopulmonary exercise testing with a cycle ergometer on another day. RESULTS: No subject experienced continuous abnormal heart rate or blood pressure response, chest pain, ischemic ST-T change, or severe arrhythmia. The peak power and the SDI were correlated with the anaerobic threshold (r = 0.42, 0.52, respectively), with peak oxygen uptake (r = 0.66, 0.61), and with the increase in oxygen uptake per unit increase in work rate (r = 0.43, 0.63). However, the slope of the ventilation equivalent to carbon dioxide output was correlated only with the SDI (r = -0.54) and the time constant for the oxygen uptake decrease was correlated only with the peak power (r = -0.46). CONCLUSIONS: Peak functional capacity depends on both muscle strength and endurance, and subjective symptoms in daily activity, especially dyspnea on exertion, depend mainly on muscle endurance in patients with chronic heart failure.

Aged↗
PubMed2004

123I-MIBG myocardial scintigraphy in patients with "takotsubo" cardiomyopathy.

UNLABELLED: The clinical characteristics of reversible left ventricular dysfunction due to "takotsubo" cardiomyopathy have been described, but the origin of this condition remains unclear. This study investigated (123)I-metaiodobenzlguanidine ((123)I-MIBG) myocardial scintigraphy in patients with takotsubo cardiomyopathy. METHODS: Eight consecutive patients with takotsubo cardiomyopathy were studied. Left ventricular wall motion was monitored by echocardiography until wall motion normalized. (123)I-MIBG myocardial scintigrams were performed within 3 d of admission (0 mo) and after the improvement of left ventricular dysfunction (3 mo). Early images were obtained at 30 min after radioisotope injection and delayed images were obtained after 4 h. The heart-to-mediastinum ratio (H/M ratio) and the washout rate were calculated. RESULTS: The mean left ventricular ejection fraction improved significantly (from 42.8% +/- 8.7% to 66.5% +/- 7.9%; P < 0.0001) and normalized after 19.4 +/- 5.4 hospital days. The early H/M ratio was significantly higher than the late ratio at 0 mo (2.16 +/- 0.25 vs. 1.89 +/- 0.24, respectively; P < 0.05), but not at 3 mo. The washout rate was significantly greater at 0 mo than at 3 mo (39.1% +/- 10.2% vs. 25.4% +/- 6.3%, respectively; P < 0.05). CONCLUSION: In patients with takotsubo cardiomyopathy, initial (123)I-MIBG myocardial scintigraphy depicted a unique pattern of ventricular asynergy and indicated the existence of cardiac sympathetic hyperactivity, although coronary blood flow was maintained. These findings strongly suggest that takotsubo cardiomyopathy could be caused by neurogenic myocardial stunning.

3-Iodobenzylguanidine↗
PubMed2003

Reversible ventricular dysfunction (takotsubo cardiomyopathy) following polymorphic ventricular tachycardia.

A 67-year-old female with recurrent syncope and no obvious heart disease developed ventricular dysfunction, known as takotsubo cardiomyopathy, following a 90 s episode of polymorphic ventricular tachycardia originating from a ventricular extrasystole with a short coupling interval. Cardiac catheterization performed 30 min after the arrhythmic event revealed angiographically normal coronary arteries, and left ventricular apical akinesis and basal hyperkinesis. An intracoronary injection of acetylcholine revealed no inducible coronary spasm, and an electrophysiological study revealed normal atrioventricular conduction and no inducible ventricular arrhythmia. Thirty hours after the arrhythmic event, electrocardiography revealed deeply inverted T waves in leads V3 to V6, I, and aVL, which continued for more than a week. Although no treatment was given to maintain hemodynamic stability, echocardiography revealed normal left ventricular contraction 14 days after the onset of the ventricular dysfunction. The reversible ventricular dysfunction might have been induced by altered catecholamine dynamics due to the persistent syncope during the occurrence of tachycardia.

Aged↗
PubMed2003

Influence of mobile magnetic resonance imaging on implanted pacemakers.

PURPOSE: Mobile magnetic resonance imaging (MRI) systems will be widely used in Japan. When traveling, mobile MRI generate alternating electromagnetic waves which may cause electromagnetic interference (EMI). This study was designed to determine whether this may influence the function of implanted pacemakers (PM). METHODS AND RESULTS: The influence of the static magnetic fields was tested in the first method using a PM-human model (Phantom). Magnetic force was simultaneously measured. The PM was switched to the magnet mode within 90 cm from the vehicle, where the magnetic force was = 2 mT. In the second method, six phantoms were placed on the side of the road, facing in three different directions in X-Y-Z axis orientations, at 1.3 m and 2.0 m above the ground. The mobile MRI passed by at a distance of 1 m from the phantoms at the speed of 20 or 40 km/h. In these experiments, magnet mode switch of the PM was observed for 2 seconds when the vehicle passed close to the phantoms, though no electrical noise was recorded. CONCLUSION: Mobile MRI vehicles can switch a PM to magnet mode when the distance between patient and vehicle is < 90 cm, regardless of whether the vehicle is moving or at a stop. Patients with implanted PM should not approach within < 1 m of a mobile MRI. No other EMI-induced PM dysfunction was detected.

Electromagnetic Fields↗