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Biomedical subjects

M Teragaki

Publications and source records attributed to M Teragaki.

69 records · Page 4Linked to original sources
PubMed1988

Relationship between cardiac function and the sympathetic nervous system during exercise in patients with essential hypertension.

The relationship between echographical cardiac function and sympathetic nerve activity during dynamic exercise was examined in patients with essential hypertension. Nine normotensives (Group N), 11 hypertensive patients without cardiac hypertrophy (Group NH) and 13 hypertensive patients with cardiac hypertrophy (Group HH) were studied during multistage exercise using a supine bicycle ergometer. The shortening fraction (SF) and the peak negative dD/dt in Group HH, being within the normal range, tended to be smaller than those in Group N at the 75-watt load. The mean value of the peak positive dD/dt (+dD/dt) in Group HH was significantly smaller than that in Group N at rest and during the 75-watt load. The percent increase of plasma norepinephrine (NE) levels (% delta NE) at the 75-watt load was significantly greater in Group HH than in Group N. Plasma NE, in some patients with cardiac hypertrophy and compromised cardiac function, markedly increased (% delta NE greater than or equal to 186) during exercise. % delta NE was directly related to the left ventricular mass index among all of the groups, but it was inversely related to the SF, -dD/dt, and to +dD/dt at the 75-watt load. We conclude that the augmented sympathetic nerve activity may contribute to preserving left ventricular systolic function during exercise within the normal range in hypertensive patients with cardiac hypertrophy.

Adult↗
PubMed1988

Physiological significance of atrial natriuretic peptides in essential hypertension.

To investigate the significance of atrial natriuretic peptides (ANP) in essential hypertension, plasma ANP concentrations in 43 essential hypertensives, 16 borderline hypertensives and 17 normotensive controls were measured. Furthermore, effects of high-sodium and low-sodium intakes on plasma ANP concentration were examined in "salt-sensitive" [SS] and "nonsalt-sensitive" [NSS] patients with essential hypertension. Plasma ANP concentration was significantly higher in hypertensives than in borderline hypertensives and in normotensive controls. No significant difference in plasma ANP concentration was observed between borderline hypertensives and normotensive controls. Plasma ANP concentration increased with the high-sodium diet in both the SS and NSS patients, but the mean increment was significantly greater in the SS than the NSS patients. Urinary excretion of sodium was lower in the SS patients taking the high-sodium diet than the corresponding value in the NSS patients. These findings suggest that an increased level of circulating ANP in hypertensive patients represents a compensatory mechanism to offset further elevation of blood pressure and sodium retention.

Atrial Natriuretic Factor↗
PubMed1988

[Regional left ventricular diastolic dysfunction in patients with apical hypertrophy].

Differences in cardiac function between the apical and the chordal parts of the left ventricle in apical hypertrophy (APH) were investigated by M-mode echocardiography. The subjects consisted of 10 patients with APH (APH Group) and 10 normal controls (N Group). The M-mode echocardiograms of the interventricular septum (IVS) and left ventricular posterior wall (LVPW), both in the apical and chordal parts were simultaneously recorded with the electrocardiogram and phonocardiogram. There were no significant differences in the blood pressures, heart rates, left ventricular end-diastolic internal diameters, and left ventricular end-systolic internal diameters between the APH Group and the N Group. The hypertrophy was localized to the IVS and LVPW of the apical part in the APH Group. In the chordal part, there were no significant differences in the peak negative dD/dt (-dD/dt) and the time to the peak filling rate (TPFR) between the APH Group and N Group. In the apical part, -dD/dt of the APH Group tended to increase compared with that of the N Group. The TPFR of the APH Group was significantly longer than that of the N Group (APH Group: 167 +- 33 msec and N Group: 126 +- 19 msec, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[Detection of left ventricular thrombi after acute myocardial infarction using Ga-67-DFO-DAS-fibrinogen].

Ga-67-DFO-DAS-fibrinogen (Ga-fbg) scintigraphy, a new radiopharmaceutical method, was performed for detecting intraventricular thrombi following acute myocardial infarction in five patients. The thrombi in four of them were detected by two-dimensional echocardiography (2DE) and that in the fifth patient was suspected during magnetic resonance imaging. Imaging of the heart was performed using a scinticamera with a medium energy collimator and multiple views (anterior, LAO 30 degrees, LAO 45 degrees, and lateral) three and four days after the intravenous administration of Ga-fbg. By Ga-fbg scintigraphy, intraventricular thrombi were detected in four patients. The size of the thrombi visualized by Ga-fbg appeared larger than those by 2DE. In one patient examined again after anticoagulant therapy, a thrombus was missed by 2-DE, but it was detected by Ga-fbg, though the radioactivity of the thrombus decreased. We concluded that Ga-fbg scintigraphy is a very simple method and sufficiently useful for detecting active left ventricular thrombi and for monitoring the effect of anticoagulant therapy. It could be more sensitive than 2DE for determining the extent of an active intraventricular thrombus.

Adult↗
PubMed1986

Histopathological study on the effects of aging in myocardium of hypertrophied hearts.

To clarify the effects of aging in myocardium of hypertrophied hearts, 555 autopsied hearts were studied histopathologically. Degrees of myocyte hypertrophy, disarrangement and fibrosis and lipofuscin deposits were estimated light-microscopically in tissue specimens taken from the anterior wall of the left ventricle. Myocyte hypertrophy was assigned to one of four classes from 0 to 3+ according to size. Other findings were estimated using the conventional three classes. All cases were divided according to heart weight, into the following groups: severe hypertrophy (Group I; more than 450 g for males and 400 g for females), mild hypertrophy (Group II; 450 greater than HW greater than 350 g for males and 400 greater than HW greater than 300 g for females) and no hypertrophy (Group III: less than 350 g for males and 300 g for females). Lipofuscin deposits increased with aging, but in Group I the increase was delayed in comparison to that in other groups. As a rule, myocyte size in the outer layer was equal to or smaller than that in the inner layer (outer-layer-selective atrophy). This was particularly true in pressure-overloaded hypertrophy and less so in volume-overloaded hypertrophy. Myocyte disarrangement was observed in the inner and median layers in the oldest group. Peri-vascular fibrosis became thick with aging, and perimysial fibrosis increased with age. The fibrotic process was accelerated in hypertrophied myocardium. As to the mode of hypertrophy, aging appears to result in a kind of myocardial asymmetry of layer-selective atrophy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Circulating atrial natriuretic polypeptide during exercise in patients with essential hypertension.

We studied the relationship between haemodynamic measurements and plasma atrial natriuretic peptide (ANP) levels during exercise in patients with essential hypertension. The exercise protocol consisted of three fixed work loads (25, 50 and 75 W) using a supine bicycle ergometer. Plasma ANP levels and haemodynamic indices were measured before and during each stage of exercise. Plasma ANP levels and pulmonary artery wedge pressure (PAWP) significantly increased at the maximum work load. Significant correlations of PAWP and mean arterial pressure (MAP) to plasma ANP levels were observed at four points obtained before and during each stage of exercise (PAWP, r = 0.83, P less than 0.001; MAP, r = 0.48, P less than 0.01). Furthermore, a significant inverse correlation between shortening fraction (SF), estimated by M-mode echocardiography, and plasma ANP levels at 75 W work load was also observed (r = -0.66, P less than 0.01). These results suggest that the increase of circulating ANP levels during exercise in essential hypertensive subjects may be associated with elevated left atrial pressure and arterial pressure, or left ventricular systolic dysfunction.

Adult↗
PubMed1985

An adult case of arrhythmogenic right ventricular dysplasia.

A forty-year-old man was admitted to our hospital because of dizziness, palpitations and an oppressive feeling in the precordium. Physical examination was normal. A chest roentgenogram revealed mild cardiomegaly and the electrocardiogram showed ventricular tachycardia of a left bundle branch block configuration which was terminated by the intravenous injection of procainamide. During sinus rhythm the electrocardiogram showed incomplete right bundle branch block, PQ prolongation and inverted T waves in leads V1 through V3. Two-dimensional echocardiography revealed only moderate right ventricular dilatation. Right ventricular angiography showed severe right ventricular dilatation and hypokinesis of the right ventricular apex and pulmonary artery infundibulum. From these characteristics signs we concluded that this adult patient had arrhythmogenic right ventricular dysplasia (ARVD), suggesting that this condition is not confined to children but may occur in adults as well.

Adult↗
PubMed1983

[Significance of the fourth heart sound in patients with angina pectoris].

To determine the physiological significance of the fourth heart sound at rest in patients with angina pectoris without previous myocardial infarction, the tension time index (TTI) and the ratio of the diastolic pressure time index (DPTI) to (DPTI/TTI) were calculated from the recordings of the left ventricular and aortic pressure curves. Thirty patients were subjected to the study and they were classified into two groups: Group A consisted of 15 patients with the fourth heart sound and Group B of 15 patients without it. Nine cases of atypical chest pain without the fourth heart sound served as control group. TTI was significantly higher in Group A than in Group B (p less than 0.01) and control group (p less than 0.01) (2,552 +/- 489 mmHg X sec/min in Group A, 2,024 +/- 425 mmHg X sec/min in Group B, and 2,023 +/- 209 mmHg X sec/min in control group). DPTI/TTI was significantly lower in Group A than in Group B (p less than 0.01) and control group p less than 0.001) (1.16 +/- 0.19 in Group A, 1.55 +/- 0.39 in Group B, and 1.45 +/- 0.15 in control group). Left ventricular systolic pressure tended to be higher in Group A than in Group B and control group. There was no significant difference in left ventricular end-diastolic pressure, left ventricular ejection fraction and cardiac index among three groups and there was no difference in the prevalence of left ventricular asynergy on left ventriculography between Group A and Group B.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Dobutamine-stress electrocardiographically gated positron emission tomography for detection of viable but dysfunctional myocardium.

PURPOSE: This study was performed to determine whether low-dose dobutamine stress electrocardiography (ECG)-gated fluorine-18 fluorodeoxyglucose (FDG)-positron emission tomography (PET) can assess wall motion and identify myocardium without contractile reserve despite preserved FDG uptake. METHODS: Fifty-three patients with myocardial infarction and normal sinus rhythm underwent ECG-gated FDG-PET and transthoracic echocardiography. Wall motion of 10 segments of the left ventricle was graded as normal, hypokinetic, or akinetic/dyskinetic. RESULTS: In 365 (76%) of 480 segments, assessment of wall motion was concordant between the 2 modalities. In 30 patients dobutamine-stress ECG-gated FDG-PET was performed. In 13 (50%) of 26 dysfunctional segments with normal FDG uptake, 16 (36%) of 44 dysfunctional segments with mildly reduced FDG uptake and 12 (25%) of 48 dysfunctional segments with moderately reduced FDG uptake, wall motion was improved by dobutamine infusion. CONCLUSION: Assessment of left ventricular wall motion with ECG-gated FDG-PET is feasible, and dobutamine stress ECG-gated FDG-PET can simultaneously identify metabolic viability and contractile reserve.

Adult↗
PubMedDate not supplied

Dobutamine stress electrocardiography-gated Tc-99m tetrofosmin SPECT for detection of viable but dysfunctional myocardium.

BACKGROUND: Technetium-99m-labeled myocardial perfusion tracers allow simultaneous assessment of myocardial perfusion and left ventricular function by electrocardiography-gated scan. This study was performed to determine whether dobutamine stress electrocardiography-gated tetrofosmin single photon emission computed tomography (SPECT) can identify viable (as defined by positron emission tomography [PET]) but dysfunctional myocardium with contractile reserve. METHODS AND RESULTS: Thirty-five patients with myocardial infarction underwent resting electrocardiography-gated SPECT and fluorodeoxyglucose (FDG) PET. The relative uptakes of tetrofosmin (%tetrofosmin) and FDG (%FDG) were calculated. Wall motion in 9 left ventricular segments was assessed at rest and during dobutamine stress on a 3-dimensional cine-mode display created with automatic left ventricular function analysis software. A total of 129 dysfunctional segments were analyzed. Forty-five (48.9%) of 92 segments with %tetrofosmin of 50% or greater and only 4 (10.8%) of 37 segments with %tetrofosmin less than 50% had contractile reserves (P <.0001). The sensitivity, specificity, and predictive accuracy of %tetrofosmin of 50% or greater for detecting %FDG of 50% or greater were 85.7%, 74%, and 82.9%, respectively. The incidence of the presence of contractile reserve rose with increasing magnitude of %FDG. The sensitivity, specificity, and predictive accuracy of the presence of contractile reserve for detecting %FDG of 50% or greater were 43.9%, 80.6%, and 52.7%, respectively. CONCLUSIONS: Dobutamine stress electrocardiography-gated SPECT can identify viable (as defined by PET) but dysfunctional myocardium with contractile reserve.

Adult↗