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Biomedical subjects

M Yotsukura

Publications and source records attributed to M Yotsukura.

At least 19 recordsLinked to original sources
PubMed2000

Value of QT dispersion in the interpretation of treadmill exercise electrocardiograms of patients without exercise-induced chest pain or ST-segment depression.

It has recently been reported that increased QT dispersion seen on standard 12-lead electrocardiograms (ECGs) reflects transient myocardial ischemia. The present study investigates whether increased QT dispersion induced by exercise is a useful indicator for detecting significant coronary stenosis in patients who do not have chest pain or significant ST-segment depression in response to exercise. We studied 135 consecutive patients (mean age +/- SD, 55 +/- 9 years; 97 men and 38 women) who complained of anginal chest pain and who did not have exercise-induced chest pain or significant ST-segment depression during treadmill exercise electrocardiography. Coronary angiography was performed in all of patients. Of the 135 patients, 97 had no significant coronary stenosis, 25 had 1-vessel coronary artery disease (CAD), and 13 had multivessel CAD. QT dispersion immediately after exercise was significantly greater in the group with significant coronary stenosis than without significant coronary stenosis (62 +/- 13 vs 40 +/- 14 ms, p <0.0001). When QT dispersion >/=60 ms immediately after exercise was considered a positive result, this indicator had a sensitivity of 74%, a specificity of 85%, and an accuracy of 81% for the diagnosis of significant coronary stenosis. In conclusion, we have shown that QT dispersion immediately after exercise is useful for detecting significant CAD in patients who do not have exercise-induced chest pain or significant ST-segment depression.

Aged↗
PubMed2000

Enhanced detection of ischemic but viable myocardium by QT interval dispersion on treadmill exercise electrocardiograms of patients with healed anterior wall myocardial infarcts.

BACKGROUND: The presence of ischemic but viable myocardium in infarcted areas is an important indication for coronary revascularization, but is often difficult to detect with the use of treadmill exercise electrocardiography (ECG). HYPOTHESIS: QT interval dispersion (QTd) is a sensitive method for detecting myocardial ischemia and may improve the accuracy of treadmill exercise ECG testing for detecting ischemic but viable myocardium in infarcted areas. METHODS: Forty-five patients with Q-wave anterior wall myocardial infarctions who underwent treadmill exercise ECG, exercise reinjection thallium-201 (201Tl) scintigraphy, radionuclide angiocardiography, and coronary angiography 1 month after infarction were enrolled in this study. The presence of viable myocardium in the infarct area was determined by exercise reinjection 201Tl scintigraphy. Patients who had no redistribution in the infarct area after reinjection were included in Group 1, and those with redistribution were included in Group 2. RESULTS: QTd immediately after exercise, and the difference between QTd before and immediately after exercise, were significantly greater in Group 2 than in Group 1. The sensitivity, specificity, and accuracy of conventional ST-segment depression criteria for detecting viable myocardium in the infarct area were 48, 64, and 56%, respectively. The measurement of QTd immediately after exercise (abnormal: > or = 70 ms; normal: < 70 ms) improved the sensitivity, specificity, and accuracy to 78, 82, and 80%, respectively. CONCLUSIONS: This novel diagnostic method using QTd-based criteria significantly improves the clinical usefulness of treadmill exercise ECG testing for detecting ischemic but viable myocardium in infarct areas in patients with healed Q-wave anterior wall myocardial infarctions.

Coronary Angiography↗
PubMed2000

Cardiac rupture and admission electrocardiography in acute anterior myocardial infarction: implication of ST elevation in aVL.

This study determines the usefulness of electrocardiography in the emergency room for assessing the risk of cardiac rupture after acute anterior myocardial infarction (MI). The presence of ST segment elevation on the admission 12-lead electrocardiography was evaluated in 325 consecutive anterior MI patients. A forward-stepwise logistic regression analysis for cardiac rupture was performed with the covariates of age, gender, hypertension, history of MI, reperfusion therapy by coronary angioplasty, and ST segment elevations in leads I, aVL, V1-V6. Cardiac rupture occurred in 16 patients, including 7 with left ventricular free wall rupture (FWR) and 9 with ventricular septal perforation (VSP). For FWR, ST elevation in lead aVL was the only independent predictor (odds ratio = 12.1, P = .0215). For VSP, female gender (odds ratio = 5.32, P = .0201) was the independent predictor. In conclusion, in patients with acute anterior MI, ST segment elevation in lead aVL on the admission electrocardiography is a significant risk factor for left ventricular FWR.

Adult↗
PubMed2000

[A case of Down's syndrome associated with testicular seminoma].

Down's syndrome is an inherited disorder caused by trisomy of chromosome 21. In patients with Down's syndrome, an increased risk of leukemia has been observed. Recently, the coincidence of testicular cancer with this syndrome has been also emphasized. We present a case of Down's syndrome associated with testicular seminoma. This is the 19th case of Down's syndrome associated with testicular tumor in Japan.

Adult↗
PubMed1999

Use of QT dispersion measured on treadmill exercise electrocardiograms for detecting restenosis after percutaneous transluminal coronary angioplasty.

BACKGROUND: Treadmill exercise electrocardiography (ECG) has been used to detect restenosis in patients following percutaneous transluminal coronary angioplasty (PTCA). However, the level of sensitivity achieved using conventional criteria of ST-segment depression is too low to be clinically useful in this population. HYPOTHESIS: QT dispersion is a sensitive method for detecting myocardial ischemia and may improve the accuracy of treadmill exercise ECG testing for detecting restenosis after PTCA. METHODS: We evaluated 104 patients who underwent PTCA for the treatment of single-vessel coronary artery disease and who had no history of myocardial infarction. Treadmill exercise ECG and coronary angiograms were performed 3 months after PTCA to determine the accuracy of diagnosis restenosis based on standard ST-segment depression and QT dispersion criteria. RESULTS: Restenosis was observed in 37 of the 104 patients (36%) 3 months after PTCA. QT dispersion immediately after exercise was significantly greater in patients with than in those without restenosis, as was the difference in QT dispersion before and immediately after exercise. The sensitivity, specificity, and accuracy of ST-segment depression criteria were 59, 64, and 63%, respectively. Measurements of QT dispersion immediately after exercise (> or = 50 ms: positive, < 50 ms: negative) improved the sensitivity, specificity, and accuracy of treadmill ECG for predicting restenosis to 81, 87, and 85%, respectively. CONCLUSIONS: This novel diagnostic method using QT dispersion-based criteria significantly improves the clinical usefulness of treadmill exercise ECG for detecting the presence of restenosis after PTCA.

Aged↗
PubMed1999

QT dispersion in patients with Duchenne-type progressive muscular dystrophy.

BACKGROUND: A high degree of QT dispersion is a risk factor for arrhythmic sudden death in patients with myocardial infarction and cardiomyopathy. Duchenne-type progressive muscular dystrophy (DMD) is also associated with the development of ventricular arrhythmias. The purpose of this study was to determine the relationship between QT interval dispersion and ventricular arrhythmias in patients with DMD. METHODS: Sixty-seven patients with DMD were studied. Standard 12-lead electrocardiograms and 24-hour Holter electrocardiograms were recorded, and the QT interval was determined in every lead of the standard electrocardiogram to determine the QT dispersion. QT dispersion was compared with the frequency of ventricular arrhythmias and the severity of skeletal muscle damage on the basis of the Swinyard and Deaver 8-stage scale. RESULTS: QT dispersion in all 67 patients averaged 54 +/- 18 ms. The QT dispersion was 49 +/- 16 ms in stage 5 patients, 61 +/- 22 ms in stage 6 patients, 52 +/- 17 ms in stage 7 patients, and 56 +/- 17 ms in stage 8 patients. Ventricular arrhythmias of Lown grade III or higher were observed in 3 of 35 patients with QT dispersion <60 ms and in 14 of 32 patients with QT dispersion >/=60 ms. Logistic regression analysis demonstrated that QT dispersion is an independent risk factor for ventricular arrhythmias of grade III or higher in patients with DMD. CONCLUSIONS: The incidence of ventricular arrhythmias of Lown grade III or higher was greater in patients with QT dispersion >/=60 ms than in patients with QT dispersion >60 ms. QT dispersion therefore is a risk factor for serious ventricular arrhythmias in patients with DMD.

Adolescent↗
PubMed1999

Clinical significance of the disappearance of septal Q waves after the onset of myocardial infarction: correlation with location of responsible coronary lesions.

We investigated the relationship between the disappearance of septal Q waves after myocardial infarction (MI) and the location of the culprit lesion. We studied 82 patients following their first anteroseptal MI who had an electrocardiogram performed before the MI. Septal Q waves were detectable before MI in 56 patients and disappeared after MI in 17 of those patients. The culprit lesion was located proximal to the origin of the first septal branch (S1) in 13 patients (76%). Disappearance of septal Q waves following MI predicted that the culprit lesion was proximal to the origin of S1 (sensitivity, 42%; specificity, 84%; predictive value, 76%; and accuracy, 61%). If septal Q waves that were detected before MI disappeared after MI, the culprit lesion was located proximal to the origin of S1 in 76% of the patients. This finding may be clinically useful in caring for patients following MI.

Adult↗
PubMed1998

Heart rate variability during the first month of smoking cessation.

BACKGROUND: Heart rate variability (HRV) is known to increase after smoking cessation. However, no work has been performed concerning HRV immediately after smoking cessation. METHODS AND RESULTS: We studied HRV before and from 1 day to 1 month after smoking cessation and also determined whether there is a relation between HRV and the withdrawal syndrome immediately after smoking cessation. We determined HRV by using a two-channel 24-hour ambulatory ECG system before and 1, 2, 3, 7, 14, 21, and 28 days after smoking cessation in 20 healthy male volunteers who had smoked one or more packs per day for 2 or more years. One day after smoking cessation, heart rate decreased significantly, and all 24-hour time and frequency domain indices of HRV increased except the standard deviations of the normal R-R intervals and the 5-minute mean R-R. The magnitude of increase in these indices peaked 2 to 7 days after smoking cessation and gradually decreased thereafter. The increase in HRV persisted 1 month after smoking cessation. In the 16 subjects with signs of withdrawal syndrome and in the four subjects without evidence of withdrawal before and immediately and 1 month after smoking cessation, HRV increased immediately after smoking cessation and remained elevated after 1 month. CONCLUSIONS: HRV increases immediately after smoking cessation and gradually declines thereafter, which suggests that the effect of smoking on autonomic activity rapidly disappears immediately after smoking cessation. HRV remained unaffected by the presence or absence of the withdrawal syndrome.

Adult↗
PubMed1998

Prognosis following acute myocardial infarction in patients with ECG evidence of left ventricular hypertrophy prior to infarction.

This study was designed to determine the relationship between prognosis after myocardial infarction (MI) and left ventricular hypertrophy (LVH). Left ventricular hypertrophy diagnosed by electrocardiography according to the criteria of Sokolow and Lyon was noted in 57 of 223 patients (25.6%) on the pre-MI electrocardiogram (ECG), in 11.2% on an early post-MI ECG, and in 11.3% on the discharge ECG. In-hospital and 1-year postdischarge mortalities were significantly greater in patients with LVH noted on pre-MI ECG than in patients without prior LVH. There was no relationship between the presence of LVH on early post-MI ECGs and in-hospital or postdischarge 1-year mortality. Multivariate analysis revealed that evidence of LVH on a pre-MI ECG and acute congestive heart failure were independent predictors of cardiac death within 1 year of MI in patients over 70 years old. It is concluded that in patients over 70 years of age, the presence of LVH on a pre-MI ECG is a reliable predictor of post-MI prognosis.

Cause of Death↗
PubMed1998

Nine-year follow-up study of heart rate variability in patients with Duchenne-type progressive muscular dystrophy.

OBJECTIVES: The purpose of this study was to investigate the progression of autonomic dysfunction in patients with Duchenne-type progressive muscular dystrophy (DMD) over time by using heart rate variability. BACKGROUND: Although previous studies suggest the presence of autonomic dysfunction in patients with DMD, the precise cause is not known. On the other hand, it is well known that analysis of heart rate variability provides a useful, noninvasive means of quantifying autonomic activity. High frequency power is determined predominantly by the parasympathetic nervous system, whereas low frequency power is determined by both the parasympathetic and sympathetic nervous systems. METHODS AND RESULTS: Frequency and time domain analyses of heart rate variability during ambulatory electrocardiographic monitoring were performed in 17 patients with DMD over a 9-year period. At the time of entry, the mean patient age was 11 years and the mean Swinyard-Deaver stage was 4. In the first year, high frequency power was significantly lower and the ratio of low frequency to high frequency was significantly higher in patients with DMD than in the normal control subjects. These differences become significantly greater as the disease progressed. At the time of entry, low and high frequency powers increased at night in both groups. However, over time, high and low frequency powers at night tended to decrease. All of the time domain parameters were significantly lower in the patients with DMD at all time points compared with the normal control subjects. CONCLUSIONS: We concluded that DMD patients have either a decrease in parasympathetic activity, an increase in sympathetic activity, or both as their disease progresses.

Adolescent↗
PubMed1997

Accuracy of treadmill exercise electrocardiography in detecting restenosis following single-vessel percutaneous transluminal coronary angioplasty.

To develop an improved method for diagnosing restenosis using treadmill exercise electrocardiography (ECG) following percutaneous transluminal coronary angioplasty (PTCA), we prospectively evaluated 46 patients who underwent PTCA for the treatment of single-vessel coronary artery disease and who did not have a history of myocardial infarction. Treadmill exercise ECG and coronary angiography were performed 3 months after PTCA to determine their accuracy in diagnosing restenosis based on standard ST-segment depression criteria, the difference between the maximum ST-segment depression before and 3 months after PTCA (< or =0.5 mm: positive; >0.5 mm: negative), and the difference between sigmaST-segment depression before PTCA and 3 months after PTCA (< or = 1.5 mm: positive; > 1.5 mm: negative). The sensitivity, specificity, and diagnostic accuracy of standard ST-segment depression criteria were 65%, 66%, and 65%, respectively. The sensitivity, specificity, and accuracy for the difference in maximum ST-segment depression were 77%, 76%, and 76%, respectively, whereas the values for the difference in sigmaST-segment depression were 77%, 83%, and 80%, respectively. Based on these results, we conclude that using the difference between ST-segment depression before and after PTCA improves the accuracy of treadmill exercise ECG for diagnosing restenosis.

Aged↗
PubMed1997

Giant negative U waves during acute myocardial infarction and ischemia.

Giant negative U waves transiently appeared in a patient with acute myocardial infarction (AMI). During hospitalization, these giant negative U waves (0.3-0.5 mV) were observed in leads V2 through V4 of the electrocardiogram (ECG). The waves disappeared 10 days after hospitalization, but reappeared during a treadmill exercise test 3 weeks after the onset of AMI. The same waves were detected again when the patient was admitted for angina pectoris 3 months later. Since these giant negative U waves appeared concomitant with myocardial ischemia, ischemia seems to be their cause. To our knowledge, there are no previous reports on reproducible U waves like those seen in this patient.

Aged↗
PubMed1996

[Arrhythmias in patients with metabolic disease].

Ventricular arrhythmias are frequently observed in patients with diabetes mellitus. On the other hand, diabetes mellitus has been associated with sudden death. Malignant ventricular arrhythmias might be one of the possible causes of sudden death. Prevalence of ventricular arrhythmias was increased with advancing severity of diabetes mellitus. The incidence of ventricular arrhythmias is closely related to occurrence of the disturbance of autonomic nervous system or the ischemic heart disease. Some papers and our present study indicate that the incidence of ventricular arrhythmias was associated with the decrease of the heart rate variability and the increase of QTc dispersion. Heart rate variability and QTc dispersion might be a good indicator of ventricular arrhythmias in patients with diabetes mellitus.

Amyloidosis↗
PubMed1995

Circadian rhythm and variability of heart rate in Duchenne-type progressive muscular dystrophy.

Using 24-hour Holter monitoring and time domain and power spectral measurements, we evaluated the variability of the heart rate and its circadian rhythm in 55 male patients with Duchenne-type progressive muscular dystrophy (DMD) to characterize their autonomic function versus findings in 20 normal controls. Comparisons were also made in patients with mild, moderate, and severe stages of DMD. The percent difference between successive RR intervals that exceeded 50 ms, a measure of parasympathetic tone, was significantly lower even in patients with early stage of DMD than in controls (p < 0.01). This trend became marked with disease progression. Power in the high-frequency (HF) range (0.15 to 0.40 Hz), a measure of parasympathetic tone, was lower (p < 0.01), and the ratio of the power in the low-frequency (LF) range (0.04 to 0.15 Hz) and that of HF range (LF/HF ratio), a measure of sympathetic tone, was higher in DMD patients versus controls (p < 0.01). This trend was also marked with disease progression. Patients with mild or moderate disease had a slight circadian alteration in HF and LF/HF ratio. Patients with severe disease had virtually no circadian rhythm in HF. Their LF/HF ratio was higher at night (p < 0.01), lower in the morning (p < 0.01), and still lower during the day (p < 0.01), the opposite of control findings. The autonomic abnormalities in DMD were thus characterized by a significant increase in sympathetic activity and a significant decrease in parasympathetic activity. Thus, heart rate variability and circadian rhythm were useful in assessing autonomic dysfunction in DMD.

Adolescent↗
PubMed1995

Transient disappearance of complete right bundle branch block during exercise in a patient with old inferior wall myocardial infarction.

To date, there has been no report of temporary disappearance of right bundle branch block (RBBB) during exercise. A patient with old infero-posterior myocardial infarction is described in whom complete RBBB disappeared transiently during treadmill exercise testing. No chest pain or significant ST-T changes occurred during and after the exercise periods. Any of the following mechanisms could have been involved: (1) the patient's complete RBBB might have been bradycardia-dependent, (2) an exercise-induced increase of sympathetic tone might have produced a temporary improvement of the conduction disturbances, or (3) the exercise might have elicited conduction disturbances in the main left bundle branch, which could have concealed a conduction delay in the main trunk of the right bundle branch.

Bundle-Branch Block↗
PubMed1994

Clinical implications of isolated T wave inversion in adults: electrocardiographic differentiation of the underlying causes of this phenomenon.

OBJECTIVES: This study aimed to assess the causes and clinical implications of isolated T wave inversion in adults and to evaluate electrocardiographic (ECG) differentiation of these causes. BACKGROUND: There are few previous reports on isolated T wave inversion in adults, which is a paradoxic observation in normal adults and in those with severe coronary artery disease. METHODS: We used echocardiography, stress thallium-201 scintigraphy and coronary angiography to determine the underlying causes and then used conventional electrocardiography and precordial ECG mapping to differentiate them. Eighty-six consecutive patients with isolated T wave inversion were classified as follows: group A included 23 asymptomatic patients; group B included 63 patients with chest pain. RESULTS: In group A, isolated T wave inversion was found as a normal variant in 20 patients and was due to hypertrophic cardiomyopathy in 3. In group B, the cause was hypertrophic cardiomyopathy in 3 patients, pericarditis in 2, coronary artery disease (lesions of the proximal left anterior descending coronary artery) in 39 and a normal variant in 19. The causes of isolated T wave inversion were difficult to determine from 12-lead ECG findings alone. However, when the inverted T wave region extended into the upper part of the precordium, precordial ECG mapping demonstrated excellent detection of coronary artery disease, with a sensitivity, specificity and overall accuracy of 88%, 93% and 91%, respectively. CONCLUSIONS: Isolated T wave inversion in asymptomatic adults is usually a normal variant. In patients with chest pain, isolated T wave inversions can develop in two different situations: a normal variant and severe coronary artery disease; these can be easily differentiated by precordial ECG mapping using conventional electrocardiography.

Adult↗
PubMed1994

Epidemiology of sudden infant death syndrome in Japan.

An epidemiological survey was carried out to examine the present situation with respect to sudden infant death syndrome (SIDS) in Kanagawa Prefecture. Questionnaires on sudden unexpected death of infants aged < 1 year in 1990-91 were sent to the hospitals and clinics in Kanagawa Prefecture which may take care of such infants. By analysing information from 10,485 replies, 48 out of 73 reported sudden infant deaths were confirmed to be SIDS, although autopsy was not performed in 13 cases (27%). The incidence of SIDS per 1000 live births in Kanagawa Prefecture was 0.29 in 1990 and 0.31 in 1991; and if limited to autopsy cases 0.19 and 0.25, respectively. Sudden infant death syndrome cases in Japan were found to occur more frequently when infants were < 6 months old, at home and sleeping alone, but less in the winter and between midnight and early morning. There was little difference between the numbers in prone and supine sleeping positions at discovery. It was not clear whether SIDS occurred more often to babies sleeping prone than supine, because there were no controls matched with the SIDS cases. In future, continuous epidemiological surveys of SIDS in Japan should be carried out.

Age Factors↗