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Biomedical subjects

I Sotobata

Publications and source records attributed to I Sotobata.

At least 91 records · Page 5Linked to original sources
PubMed1984

Correlation between the direction of the interventricular septum estimated with transmission computed tomography and the initial QRS vectors.

A correlative study was performed to relate the interventricular septal angle (As degrees) evaluated by transmission computed tomography to the azimuth of initial QRS vectors in 52 patients. Patients were divided into five groups: RV volume overloading (RVO), RV pressure overloading (RSO), LV volume overloading (LVO), LV pressure overloading (LSO), and normal control with no cardiopulmonary disease. For measurement of As degrees, the leftward and forward directions were designated as zero and 90 degrees, respectively. The mean value of As degrees was significantly smaller in RVO (14.4 degrees) and RSO (41.1 degrees) than in normal controls (50.4 degrees) and in LVO (53.2 degrees). The mean value of the azimuth of the initial 12-msec instantaneous QRS vectors (H 12 degrees) was significantly smaller in RVO (80.5 degrees), RSO (81.7 degrees), and LSO (81.3 degrees) than in normal controls (113.8 degrees and in LVO (113.7 degrees). A significant linear correlation was shown between As degrees and H12 degrees in a combined group consisting of RVO, LVO, and normal controls (r = 0.70, p less than 0.001), and also in another combined group consisting of RSO, LSO, and normal controls (r = 0.52, p less than 0.01). It was concluded that the orientation of the interventricular septum was one of the major determinants of the direction of initial QRS vectors, especially in patients with ventricular volume overload or without cardiopulmonary disease.

Adolescent↗
PubMed1984

Effects of treadmill exercise on platelet functions and blood coagulating activities in healthy men.

The effects of treadmill exercise (up to 85% of the predicted maximum heart rate) on platelet functions and coagulating activities were studied in 26 normal men. Blood sampling for the measurements were performed from the antecubital vein at rest, at 3, 6, 9, and 12 min during exercise, immediately postexercise, and at 6 and 30 min after exercise. Measurements for blood analysis included the following: platelet sensitivity and percent aggregation to ADP, platelet counts, plasma thromboxane B2 and 6-keto-prostaglandin F1 alpha levels, plasma epinephrine and norepinephrine levels, plasma fibrinogen level, activity of plasma antithrombin III, and of plasma factors VIII, IX, XI, and XII. No significant changes were induced by dynamic leg exercise in platelet sensitivities and the maximum and 3-min percent aggregation. The platelet counts increased during exercise in platelet-rich plasma without a significant change in that in whole blood. During exercise, plasma thromboxane B2 levels showed a tendency to increase, while plasma 6-keto-prostaglandin F1 alpha levels to decrease. Plasma epinephrine levels showed a tendency to increase and norepinephrine levels increased during exercise. Among coagulating factors, factor VIII activities and fibrinogen levels increased without altering activities of factors IX, XI, and XII. Antithrombin III activities also increased during exercise. In spite of significant changes in several coagulating factors, prothrombin time and partial thromboplastin time were not influenced by exercise. In conclusion, dynamic leg exercise of a moderate to high intensity produced a significantly elevated plasma level of factor VIII, fibrinogen, antithrombin III, and catecholamines without affecting the hemostatic balance in normal subjects.

Adult↗
PubMed1984

Changes in the effects of clonidine on left atrium and hindlimb vasculature of rats in various thyroid states. A study of the responsiveness of alpha 2-adrenoceptors in the cardiovascular system.

Postsynaptic alpha 2-adrenoceptors have been reported to exist in various tissues, including vascular smooth muscle. In order to investigate the possibility of their mediating a positive inotropic change and clarify the influence of the thyroid on their responsiveness, we examined the effects of clonidine, a known alpha 2-agonist, on the isolated left atria and femoral vascular beds of rats which were made hypo-, hyper- or euthyroid. Clonidine caused a dose-dependent positive inotropic change in the hypothyroid rat atrium, which was thought to be due to its alpha 1-stimulating action because of the antagonistic effect exerted by either phentolamine (10(-6) M) or prazosin (10(-7) M), but not by yohimbine (10(-7) M) or cimetidine (10(-5) M). In the hyperthyroid rat atrium, clonidine exerted a negative inotropic effect at high concentrations, which was thought to be due to its direct action on the cardiac muscle. Clonidine did not cause any inotropic change in the euthyroid rat atrium. Thus, an inotropic change mediated by the postsynaptic alpha 2-adrenoceptors could not be demonstrated in the rat heart. In the experiment involving hindlimb perfusion, clonidine caused vasoconstriction which was antagonized by yohimbine (10 micrograms/min). This effect was significantly augmented in the hypothyroid rats but not changed in the hyperthyroid ones. The vasoconstrictive effect of phenylephrine was found to be reduced in both hypo- and hyperthyroid rats. These results suggest that, in the peripheral vascular system, thyroid function also influences the postsynaptic alpha 2-adrenoceptors, but not in the same way as it affects the alpha 1-adrenoceptors.

Animals↗
PubMed1984

[Quantitative correlation between thallium-201 myocardial emission computed tomography and left ventriculography in old myocardial infarction].

We evaluated a clinical usefulness of quantitative analysis of myocardial emission computed tomographic (ECT) images in 28 patients with old myocardial infarction and 10 healthy volunteers. Circumferential profile analysis was performed in five or six short-axial images of the left ventricle reconstructed from ECT. Mean regional anterior, inferoposterior, lateral and septal percent thallium uptakes were calculated from three short-axial (basal, central and apical) images. The percent infarct size was evaluated as a percentage of the thallium perfusion defect volume to the total left ventricular myocardial volume. Left ventricular hemiaxis shortening was calculated at three ventricular levels corresponding to the three short-axial ECT images. Mean value of all hemiaxis shortening in RAO and LAO projections (total hemiaxis shortening) and left ventricular ejection fraction (EF) were obtained. There was a significant correlation between mean percent thallium uptake and percent hemiaxis shortening in the left ventricular anterior and inferoposterior segments. On the contrary, no statistically significant correlation was shown between these two parameters in the left ventricular lateral and septal segments. Percent infarct size obtained with ECT significantly correlated with total hemiaxis shortening and EF (r = -0.63 and -0.60, respectively). It was concluded that there is a close relationship between the size of infarcted myocardium evaluated by ECT and either of the regional or global left ventricular dysfunction assessed by LVG.

Adult↗
PubMed1984

[Quantitative analysis of exercise 201Tl myocardial emission CT in patients with coronary artery disease].

The clinical usefulness of quantitative analysis of exercise thallium-201 myocardial emission computed tomography (ECT) was evaluated in coronary artery disease (CAD). The subjects consisted of 20 CAD patients and five normal controls. All CAD patients underwent coronary angiography. Tomographic thallium-201 myocardial imaging was performed with a rotating gamma camera, and long-axial and short-axial myocardial images of the left ventricle were reconstructed. The tomographic images were interpreted quantitatively using circumferential profile analysis. Based on features of regional myocardial thallium-201 kinetics, two types of abnormalities were studied: diminished initial distribution (stress defect) and slow washout of thallium-201, as evidenced by patients' initial thallium-201 uptake and 3-hour washout rate profiles which fell below the normal limits, respectively. Two diagnostic criteria including the stress defect and a combination of the stress defect and slow washout were used to detect coronary artery lesions of significance (greater than or equal to 75% luminal narrowing). The ischemic volumes were also evaluated by quantitative analysis using thallium-201 ECT. The diagnostic accuracy of the stress defect criterion was 95% for left anterior descending, 90% for right, and 70% for left circumflex coronary artery lesions. The combined criteria of the stress defect and slow washout increased detection sensitivity with a moderate loss of specificity for identifying individual coronary artery lesion. A relatively high diagnostic accuracy was obtained using the stress defect criterion for multiple vessel disease (75%). Ischemic myocardial volume was significantly larger in triple vessel than in single vessel disease (p less than 0.05) using the combined criteria.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

[Effects of heart rate on body surface potential distribution in patients with atrial pacemaker].

Nine patients of sick sinus syndrome with atrial programmable pacemaker (3 males and 6 females, aged from 53 to 72 years) were studied to assess the effect of heart rate on the body surface potential distribution. Body surface maps (87 lead points) and M-mode echocardiograms were recorded at 20-beat increments of heart rate from 60 to 140 beats/min during atrial pacing. The potential changes of R and S voltages were evaluated quantitatively and were correlated with the changes of echocardiographically measured left ventricular dimension. As the heart rate increased, left ventricular dimension in end-diastole (LVDd) decreased gradually (Table 1), and a significant decrease was observed when the heart rate increased from 80 to 100 beats/min and from 100 to 120 beats/min, respectively, (p less than 0.05). With a decrease in LVDd, the distance between the left ventricular posterior wall and the anterior chest wall decreased and the left ventricular wall increased in its thickness. These changes, however, were not statistically significant. With an increase in the heart rate, R voltages decreased gradually in the left lateral chest and the sum of R voltages (sigma R) of six lead points in the left lateral chest including leads V5-6 decreased significantly when the heart rate increased from 60 to 100 beats/min and from 80 to 120 beats/min, respectively (p less than 0.02) (Table 2). On the other hand, R voltages remained unchanged in the left anterior chest during atrial pacing, then the sum of R voltages of six lead points in the left anterior chest including leads V2-4 and the sum of R voltages of 87 lead points did not show any significant changes (Table 2). An increase in the absolute value of S voltages was observed in the left anterior chest and the sum of S voltages of six lead points in the left anterior chest including leads V2-4 increased when the heart rate increased from 60 to 100 beats/min and from 80 to 120 beats/min, respectively (p less than 0.1) (Table 3) A decrease of R voltages in the left lateral chest was consistent with the reduction in LVDd (p less than 0.005). It is concluded that the changes in body surface QRS amplitudes during atrial pacing are related to those in the left ventricular dimension and that R voltages in the left lateral chest are fairly sensitive to see the changes in LVDd in cases with no abnormal wall motion of the left ventricle.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1983

A two-dimensional analysis of regional myocardial function in the dog.

The pattern of left ventricular contraction or relaxation is not uniform and also changes depending on hemodynamic states. Accordingly, the measurement of myocardial segment length only may have limitations for the analysis of regional myocardial function, and a two-dimensional analysis of regional myocardial function was developed and characterized by utilizing measurement of regional myocardial surface area on the epicardial surface. In eight anesthetized open-chest dogs, the relationship between regional myocardial function and total cardiac function was examined. The extent of the reduction of regional myocardial surface area during the ejection phase or during the systolic phase correlated more closely with stroke volume over wide ranges of left ventricular end-diastolic pressure, aortic pressure, left ventricular contractility, and heart rate (r = 0.75 - 0.96) than the shortening of myocardial segment length alone. Thus, the results demonstrated that regional myocardial function estimated by the measurement of regional myocardial surface area represents total cardiac function more accurately than myocardial segment length over wide ranges of hemodynamic states despite the changes in the left ventricular contraction and relaxation pattern.

Animals↗
PubMed1983

Distribution of abnormal Q waves on body surface in relation to left ventricular wall motion abnormalities in myocardial infarction.

This study was undertaken to determine the possible one-to-one relationship between each site of asynergy of the left ventricle and the body surface area to which ensuing abnormal electrical phenomena are reflected. In 140 post-myocardial infarction (MI) patients, distribution of abnormal Q waves on the body surface was correlated with the abnormal segments of LV wall motion identified by left ventriculography (LVG). Unipolar lead electrocardiograms (ECGs) were recorded from 87 lead points over the precordium and the back with Wilson's central terminal as the reference point. Data acquisition and mapping was accomplished through a mapping system HPM 5100 microcomputer. In all cases, coronary arteriography (CAG) and LVG were performed at least 2 months after the acute episode of MI. The LVG findings were evaluated separately in seven wall segments in accordance with the American Heart Association (AHA) reporting system. Sensitivity, specificity, diagnostic accuracy, positive predictive value, and negative predictive value of the abnormal Q wave in each lead point were obtained in cases with abnormal wall motion in segments 2, 3, and 6, respectively, and in infero-posterior segments 4 or 5. Statistical analysis was performed by comparing two groups of patients with or without asynergy of each wall segment concerned. Results of the study revealed some abnormal Q areas of high diagnostic accuracy that correlated highly with the site of abnormal contractility.

Journal Article↗