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Biomedical subjects

M Yotsukura

Publications and source records attributed to M Yotsukura.

At least 19 recordsLinked to original sources
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↗
PubMed1992

The prevalence and prognostic significance of arrhythmias in Duchenne type muscular dystrophy.

To investigate the prevalence and prognostic significance of cardiac arrhythmias in Duchenne type muscular dystrophy 24-hour ambulatory ECG was performed in 80 patients with Duchenne type muscular dystrophy, and they were followed up for 5 years. Various arrhythmias were observed in 63.8% (51 of 80) of the patients. Ventricular premature beats were found in 30% (24 of 80), and the incidence of ventricular premature beats increased as the clinical severity of skeletal muscle involvement advanced. Forty-seven patients survived for 5 years, but the incidence of arrhythmias increased from 38.3% (18 of 47) to 74.5% (35 of 47) (p < 0.001). During the 5-year period, four of 33 deaths were sudden. Malignant ventricular premature beats (ventricular couplets, ventricular tachycardia, and R-on-T-type ventricular premature beats) were observed in three of these four patients. It appears that cardiac arrhythmias are a common complication of Duchenne type muscular dystrophy and that the incidence of ventricular arrhythmias increases with the progression of myocardial involvement. There is an association between ventricular arrhythmias and sudden death, but the reduction of ventricular arrhythmias may not reduce the incidence of episodes of sudden death.

Adolescent↗
PubMed1992

A 10-year follow-up study by orthogonal Frank lead ECG on patients with progressive muscular dystrophy of the Duchenne type.

A 10-year follow-up study by orthogonal Frank lead electrocardiography was performed on 25 patients with progressive muscular dystrophy of the Duchenne type (DMD). With advancing age, no apparent changes were observed in the duration and amplitude of the P wave or in the PR interval, whereas the duration of the QRS complex tended to increase. The amplitudes of the R wave in lead X (Rx) and lead Y (Ry) tended to decrease from 1.75 +/- 0.90 and 1.96 +/- 0.59 mV to 0.80 +/- 0.63 and 1.39 +/- 0.62 mV (p < 0.01), whereas the amplitude of the S wave in lead X tended to increase from 0.24 +/- 0.23 mV to 0.53 +/- 0.36 mV in 10 years after initiation of the study (p < 0.01). It is noteworthy that the Ry amplitude began to decrease markedly from the seventh year after the initiation of this study, whereas the Rx amplitude showed a gradual and unceasing decline through the 10-year period. Observation of the sequential changes of the QRS loops in three planes clearly demonstrated that the electrical force tended to decrease in the leftward and inferior directions and increase in the rightward direction. It is of interest that the frequency of occurrence of the deep Q wave was found to be quite high even in the early stages of DMD and that it did not display a direct relation to the sequential evolution of this disease. It can be concluded that observation of the sequential changes in the QRS complex allows estimation of the extent and direction of myocardial involvement in DMD.

Adolescent↗
PubMed1991

Late potentials in progressive muscular dystrophy of the Duchenne type.

This study describes the late potentials (LPs) obtained by signal-averaged electrocardiography (SAECG) in 66 patients with Duchenne's progressive muscular dystrophy (DMD). It also assesses the possible relationships between LPs and the severity of DMD, and the findings of two-dimensional echocardiography, as well as ventricular arrhythmias examined with the Holter system. SAECGs were performed with a Marquette MAC-1 unit. Based on Swinyard-Deaver's system of stages, ranging from the mildest, S1, to the most severe, S8, one patient each could be assigned to S2 and S4, 6 to S5, 20 to S6, 21 to S7, and 17 to S8. LPs were observed in 21 of the 66 patients (32%), including 3 of the 20 assigned to S6 (15%), 10 of the 21 in S7 (48%), and 8 of the 17 in S8 (47%). The total wall motion index evaluated by the method of Hegar was significantly greater in the patients with LPs (8.4 +/- 4.4) than in those without LPs (5.8 +/- 3.1) (p less than 0.05). The incidence of LPs was found to be higher in the dilated cardiomyopathy (DCM) type (8 of 12;67%) than in the normal type (9 of 41;22%) (p less than 0.01). The incidence of ventricular premature complexes (VPCs) was significantly higher in patients with LPs (13 of 21;62%) than in those without LPs (13 of 45;29%) (p less than 0.05). No sustained ventricular tachycardia (VT) was observed, although nonsustained VT was noted in three patients with LPs. The LPs in patients with DMD were thus associated with left ventricular dysfunction, and the presence of LPs might be correlated with the extent of myocardial derangement in DMD.

Adolescent↗
PubMed1991

Review of a case of tsutsugamushi disease showing myocarditis and confirmation of Rickettsia by endomyocardial biopsy.

A patient suffering from tsutsugamushi disease underwent endomyocardial biopsy for the purpose of diagnosis of myocarditis. Proliferation of Rickettsia tsutsugamushi was observed in the vascular endothelial cells of the myocardium. There have been no reports describing the identification of Rickettsia tsutsugamushi endomyocardial biopsy. This report indicates that endomyocardial biopsy may be a useful adjunct to the clarification of myocardial involvement of Rickettsia tsutsugamushi.

Adult↗
PubMed1988

Pulmonary hypertension in progressive muscular dystrophy of the Duchenne type.

Right heart catheterization was performed in 8 patients with progressive muscular dystrophy of the Duchenne type (DMD) at the advanced stage. A mean pulmonary arterial pressure in excess of 20 mmHg was observed in all cases. Five of them showed severe pulmonary hypertension with a mean pressure above 40 mmHg. Since pulmonary hypertension was relieved by correction of hypoxemia, this represented a precapillary pulmonary hypertension caused by constriction of the pulmonary artery. Furthermore, elevation of the mean right atrial pressure above 5 mmHg was observed in 6 of the 8 cases, indicating the possible presence of right ventricular failure. Despite the presence of left ventricular dysfunction as assessed by echocardiogram, no manifestations of left ventricular failure, such as dyspnea and pulmonary rales, were noted in any of the patients. In conclusion, it can be said that even in the terminal stage of DMD, the left ventricular function may, in fact, still remain not markedly involved, and that respiratory failure, as well as right ventricular failure caused by precapillary pulmonary hypertension, will tend to occur frequently and may play a determinant role in prognosis of the advanced DMD patient.

Adolescent↗
PubMed1986

Influence of peripheral intravenous contrast injection on the QRS complex in healthy men.

The influence of acute plasma expansion induced by the administration of sodium containing hyperosmolar contrast medium on Frank lead electrocardiograms was investigated in 10 healthy male volunteers. The major electrocardiographic changes after injection of the contrast medium were a significant decrease in the amplitudes of Rx, Ry, and Qz and the maximal spatial QRS voltage, and a significant increase in the amplitude of Sx. The echocardiographic left ventricular end diastolic dimension tended to be larger after the injection, whereas no significant change occurred in the left ventricular systolic dimension. The electrocardiographic changes in this study were the opposite of those expected with the Brody effect. Although the precise mechanism underlying these findings is unclear, the increased intracardiac blood volume may have caused a decrease in the QRS voltage by a short circuiting effect. Alternatively if the activation in the left ventricle is assumed to be predominantly tangential the QRS voltage should have decreased with the Brody effect. The Brody effect may lead to an erroneous interpretation of electrocardiograms in certain clinical settings.

Adult↗