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Biomedical subjects

S Yasui

Publications and source records attributed to S Yasui.

At least 199 records · Page 11Linked to original sources
PubMed1982

Treadmill stress test using body surface mapping in coronary artery disease--the clinical significance of ST depression.

In this study we assessed in 27 patients with coronary artery disease whether the size of the ST-depression area, which was measured by body surface maps recorded before and after treadmill exercise, could be a useful indicator for evaluating coronary artery disease (CAD) quantitatively. The patients were divided into 3 groups on the basis of the findings of the left ventriculograms: patients with anterior asynergy (n = 6), those with inferior asynergy (n = 6) and those with no asynergy (n = 15). Coronary arteriograms were evaluated according to Pujadas, and epsilon Grade, as an index of the severity of CAD, was developed by adding the grade numbers of the 4 main coronary stems (right coronary artery, main trunk of the left coronary artery, left anterior descending artery and left circumflex artery). Patients with inferior asynergy and with no asynergy have ST-depression areas in proportion to their epsilon Grade (r = 0.845, p less than 0.001), whereas none of the patients with anterior asynergy showed ST-depression areas regardless of their epsilon Grade. Of 6 patients who had anterior asynergy, 5 (83%) had pathologic Q waves in the left anterior chest leads. These findings emphasize the clinical value of the ST-depression are for the quantitative and non-invasive diagnosis of CAD, especially in patients without pathologic Q waves in the left anterior chest leads.

Adult↗
PubMed1982

Influences of the alteration in aortic pressure on regional myocardial function and regional myocardial blood flow in partial coronary artery occlusion.

This study was designed to simultaneously evaluate the effects of alterations in aortic pressure (AoP) on regional myocardial function and regional myocardial blood flow (MBF) in anesthetized dogs with partial coronary occlusion. Regional myocardial function was assessed by both segment-length and tension gauges. The left circumflex coronary artery flow was reduced to 50 to 70% by a constrictor. When systolic aortic pressure (AoPS) fell from 103.6 +/- 7.4 to 72.5 +/- 4.9 mmHg following nitroprusside infusion, systolic shortening (SS) markedly depressed from 0.63 +/- 0.17 to 0.09 +/- 0.20 mm (p less than 0.01), developed tension (DT) decreased by 30% (p less than 0.01), and MBF assessed with tracer microspheres decreased from 0.61 +/- 0.13 to 0.36 +/- 0.11 ml/min/Gm (p less than 0.01) in ischemic regions. In non-ischemic regions SS was enhanced from 0.78 +/- 0.16 to 0.89 +/- 0.15 mm (p less than 0.05), but DT and MBF showed no changes. An elevation of AoPS from 106.4 +/- 5.6 to 143.3 +/- 6.9 mmHg following methoxamine infusion brought about enhanced SS from 0.42 +/- 0.15 to 0.48 +/- 0.09 mm (p less than 0.05), a 50%-increase in DT (p less than 0.01), and was associated with an increase in MBF from 0.66 +/- 0.03 to 1.19 +/- 0.07 ml/min/Gm (p less than 0.01) in ischemic regions. These results indicate that, in partial coronary occlusion, a fall of AoP induces redistribution of blood flow away from ischemic regions and aggravates the function of the ischemic myocardium, while an elevation of AoP may produce beneficial effects upon the ischemic myocardium.

Animals↗
PubMed1982

The beneficial effect of diltiazem on exercise-induced ST depression, measured by body surface mapping, in stable effort angina pectoris.

The effect of diltiazem, a calcium antagonist, was examined in eight male patients with stable effort angina pectoris by means of multistage treadmill testing using body surface mapping. The area and severity of exercise-induced ST depression after 90 mg of diltiazem administered orally three hours before exercise were compared with those without diltiazem. Although the same workload was performed, the area and severity of exercise-induced ST depression were significantly diminished (P less than 0.005) after diltiazem. The reproducibility of these observations was confirmed in two of the eight patients studied and in three other patients. Because exercise-induced ST depression in patients with coronary artery disease is generally believed to reflect myocardial ischemia, our results provide objective evidence that diltiazem is able to reduce the exercise-induced myocardial ischemia in effort angina pectoris.

Aged↗
PubMed1981

Quantitative evaluation of treadmill test induced ST-T changes using body surface mapping.

Using the ST difference map after the treadmill exercise test, the 26 patients with coronary artery disease were studied. 1) The extent and the speed of complete recovery of ST depression or negative area were well correlated with the severity of coronary artery disease. 2) ST elevation or positive area was correlated with regional asynergies. 3) ST elevation area disclosed regional defect of 201 T1 scintigram at rest, while ST depression area could disclose it infrequently.

Adult↗
PubMed1981

The quantitative diagnosis of thallium-201 myocardial perfusion images and vectorcardiograms in myocardial infarction and hypertrophic cardiomyopathy.

Correlation studies were carried out between thallium-201 myocardial perfusion images and vectorcardiograms in 77 patients with myocardial infarction (48 anterior and 29 inferior infarctions) and 30 patients with hypertrophic cardiomyopathy. A quantitative method was developed; myocardial 201Tl uptake index (a relative myocardial activity to background, MUI) and myocardial 201Tl uptake ratio (a ratio of regional myocardial counts to maximal myocardial counts, MUR) were utilized to differentiate myocardial infarction from hypertrophic cardiomyopathy, and evaluate them. A fairly good agreement between left ventriculograms and myocardial perfusion images was obtained in myocardial infarction (diagnostic accuracy 95.1% in anterior and 75.6% in inferior infarction). In anterior infarction the linear relationship of r = -0.58 (p < 0.001) was obtained between asynergy index and mean anterior MUR. A highly significant correlation was observed between anterior MUR and the instantaneous 24 msec Z component (r = -0.80, p < 0.001). In inferior infarction, Qy/Ry was correlated to inferior MUR (r = -0.58, p < 0.001). In hypertrophic cardiomyopathy, four types of hypertrophic sites were classified with 201Tl images (septal, apical and anterior, apical and septal, and anterior dominant types). Azimuth angles of instantaneous 10 msec vector were directed right-anteriorly (mean 114.5 degrees) in septal hypertrophy, and left-anteriorly (mean 84.9 degrees) in apical and anterior hypertrophy. Elevation angle of maximal T vector in apical hypertrophy was deviated superiorly (mean 102.6 degrees). There was a good correlation (r = 0.60, p < 0.001) between the magnitude of spatial maximal QRS vector and lateral wall MUR.

Adolescent↗
PubMed1981

Treadmill exercise test using body surface mapping. A quantitative diagnostic method for coronary artery disease.

In order to evaluate coronary artery disease quantitatively we recorded body surface maps before and after treadmill exercise in 27 patients suspected of having coronary artery disease. Electrocardiograms were recorded from 87 points on the anterior and posterior chest wall. The pre-exercise ST level was subtracted from post-exercise ST level at each lead point and an ST difference MAP was constructed. The ST level at 60 msec from J point was used for the construction of the ST difference MAP. By means of ST difference MAP, the area with ST changes which was induced by treadmill exercise could be evaluated. the size of the ST-depression area in the ST difference MAP was considered to be proportional to the severity of the coronary artery disease and the ST-elevation area was closely correlated to the motion abnormality of the corresponding left ventricular wall. Treadmill exercise test using body surface mapping has provided a measure of quantitative diagnosis of coronary artery disease especially in symptomatic patients.

Adult↗
PubMed1980

Effects of niludipine on regional myocardial blood flow and regional myocardial function in the dog with partial occlusion of the coronary artery.

The effects of bis(2-propoxyethyl)-1,4-dihydro-2,6-dimethyl-4-*3-nitrophenyl)-3,5-pyridine dicarboxylate (niludipine), a newly-synthesized calcium antagonist related in chestical structure to nifedipine, on the ischemic myocardium were studied in eight anesthetized, open-chest dogs, mainly by the simultaneous measurement of regional myocardial blood flow (MBF) and regional myocardial function. The ischemic myocardium was prepared by partial occlusion of the left circumflex coronary artery, and niludipine was given i.v. at a dose of 5 micrograms/kg. MBF was measured by the radioactive microsphere method and regional myocardial function was assessed by measurement of myocardial segment length. Measurements were also taken of aortic pressure, left ventricular pressure, ascending aortic blood flow, and left circumflex coronary blood flow. Niludipine decreased left ventricular contractility, dilated resistance vessels and reduced heart rate. MBF, measured 5 min after the drug was administered, increased in both the ischemic and the non-ischemic myocardium. Improvement in regional myocardial function was observed in the ischemic myocardium 5 min later, when aortic pressure had returned to nearly the pre-administration level. Thus, the results of the study suggest that niludipine improves the balance between myocardial energy supply and demand in the ischemic myocardium when there is little change in aortic pressure, and we concluded that niludipine exerts a beneficial effect on the ischemic myocardium

Animals↗
PubMed1979

Effect of the autonomic blockade on the automaticity of the A-V junctional pacemaker in awake dogs.

The effect of the autonomic blockade on the automaticity of the A-V junctional pacemaker was evaluated in 15 awake dogs with experimentally induced A-V junctional rhythm. The duration of asystole after overdrive (D.A.O.) in these dogs was prolonged significantly in accordance with increase in the drive rate, and the mean +/- SD of the D.A.O. reached 4.7 +/- 1.1 seconds (N = 15) after overdrive at 2.5 times the spontaneous heart rate. After administration of atropine (0.4 mg/kg; i.v.) to eight dogs, the mean +/- SD of the D.A.O. at the same rate decreased from 4.5 +/- 0.9 to 3.4 +/- 1.2 seconds. After administration of practolol (0.5 mg/kg; i.v.) to the seven other dogs, the mean +/- SD of the D.A.O. at the same rate increased remarkably from 4.9 +/- 1.3 to 9.4 +/- 3.0 seconds. Intravenous injection of practolol (0.5 mg/kg) had no effect upon the D.A.O. in the five dogs with sinus rhythm. Thus, it is suggested that (1) the sympathetic nerve might play a more important role in regulating the automaticity of the A-V junctional pacemaker than the vagus and (2) it physiologically might take over 5.0 seconds for the A-V junctional pacemaker to initiate an escape beat during longstanding sinus arrest, if a marked dysfunction of the A-V junctional pacemaker occurs due to a decrease in tension of the sympathetic nerve.

Animals↗