Biomedical subjects
Publications and source records attributed to M Akisada.
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The relationship between magnetic resonance (MR) relaxation times and muscle fiber composition was investigated in 16 men, and a high positive correlation was found. Higher proportions of fast-twitch fiber were associated with longer relaxation times, indicating that fast-twitch fiber has a longer relaxation time than slow-twitch fiber. Multiple regression analysis, conducted to investigate the suitability of relaxation time as a model of estimating muscle fiber composition, revealed that T1 and T2 were significantly related to muscle fiber composition. These results indicate that MR relaxation time may be used to estimate muscle fiber composition.
In spite of numerous available diagnostic methods, controversies concerning the precise diagnosis of tricuspid regurgitation (TR) still remain. In right ventriculography, catheter placement may modify tricuspid valvular function. Though noninvasive Doppler echocardiography is a useful method, it is sometimes too sensitive for clinical use. Furthermore, it is not applicable to cases in which ultrasound penetration is limited. In this study, we evaluated TR using intravenous digital subtraction angiography (DSA), which can provide good images even in cases with poorly recorded echocardiograms. For this study, we placed a catheter in the superior vena cava. Cardiac DSA examinations were performed in one hundred and one patients with heart disease. We injected 35 ml of contrast medium at a speed of 18 ml/sec via a catheter introduced in the superior vena cava. DSA images by continuous mode were obtained in the RAO projection for 15-20 sec. Sequential DSA images were observed and analyzed by time-density curves of the regions of interest (ROI) which were placed in the right ventricle (RV) and inferior vena cava (IVC). Doppler echocardiography was performed for 16 cases in which TR was suspected. Of these, phonocardiography with jugular pulse tracing was recorded for 14 and contrast echocardiography were performed for six, respectively. In cases without evidence of TR, regurgitation of contrast medium into the IVC during RV systole was not recorded by the DSA method. In cases of clinically-proven TR, regurgitation into the IVC during RV systole was observed. Thus, this was considered a diagnostic feature of positive TR using the DSA method, and 13 of the 16 cases undergoing Doppler echocardiography were diagnosed as having TR using the DSA method. The severity of TR was categorized as mild, moderate and severe according to analyses of time-density curves. The severity established by the DSA method showed a close correlation with the clinical severity of TR. Doppler echocardiography was negative for TR in two of the 13 cases, but positive for TR in two of the 16 suspected cases only by the Doppler method. In cases of moderate to severe TR diagnosed by the DSA method, jugular pulse tracings showed a regurgitant wave. By contrast echocardiography, TR was evident only in cases of severe TR diagnosed by the DSA method. In conclusion, the DSA method proved useful for diagnosing TR.
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To assess neurohumoral and hemodynamic responses to exercise in patients with exertional angina, we measured plasma norepinephrine (NE) concentrations in 23 patients with exertional angina (with no heart failure) and compared the results with their coronary arteriographic findings. The 23 patients were divided into two groups: 14 cases with multiple vessel disease (MVD) and 9 cases with one-vessel disease. At resting state there were no significant differences between the two groups in levels of NE. At maximal exercise there were no significant differences between the groups in increases of heart rate, blood pressure, and rate-pressure product, but exercise-induced increase of plasma NE (%) was significantly larger in MVD (131.6 +/- 95.4%) (mean +/- SD) than in one-vessel disease (69.0 +/- 45.3%) (p less than 0.01). In conclusion, plasma NE responses to exercise differ between patients with multiple vessel disease and patients with one-vessel disease.
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The purpose of this study was to evaluate the acute effects of sublingual nifedipine (10 mg) on left ventricular systolic function (ejection fraction, peak ejection rate, time to peak ejection rate) and diastolic function (peak filling rate, time to peak filling rate, filling fraction during rapid filling) at rest and during exercise using radionuclide angiography in 17 patients with ischemic heart disease. The results of the study were as follows. Diastolic indexes in the patient group were significantly different from the values in the control group at rest and during exercise. Peak filling rate and filling fraction improved significantly after nifedipine administration. These values did not show significant differences from the values in normal subjects which were obtained before nifedipine administration. The peak filling rate during exercise after nifedipine administration increased significantly, although the value was lower than that in the control group. At rest, systolic indexes in the patient group showed abnormal values, although the differences from the control values were not significant. Ejection fraction and peak ejection rate were significantly lower than those in the control group during exercise. After nifedipine administration, peak ejection rate at rest and during exercise, and ejection fraction at rest in the patient group improved significantly. Seven of 17 achieved the same exercise workloads as control conditions without symptoms or ECG changes. These data suggest that nifedipine improved left ventricular systolic and diastolic dysfunction, as well as exercise tolerance in patients with ischemic heart disease.
The comparative sensitivities of exercise (supine ergometer), isoproterenol (ISP) infusion and cold pressor test (CPT) for detecting myocardial ischemia in patients with effort angina (45 cases) and vasospastic angina (16 cases) were investigated. Twenty-three patients with atypical chest pain served as normal controls. Left ventricular function was evaluated by computerized quantitative analysis using the following three graphic methods: 1) radionuclide angiography during exercise (EX-RI) and ISP infusion (ISP-RI), 2) two-dimensional echocardiography during ISP infusion (ISP-2DE) and CPT (CP-2DE) and 3) digital subtraction angiography during CPT (CP-DSA). The incidence of regional wall motion abnormalities (WMA) induced by these three stress tests in patients with effort angina were as follows: 83% in EX-RI, 80% in ISP-2DE, 80% in ISP-RI, 75% in CP-2DE and 86% in CP-DSA. In patients with vasospatic angina, the WMA were as follows: 40% in EX-RI, 0% in ISP-RI and 71% in CP-DSA. In patients with atypical chest pain, the WMA were 0% in EX-RI, 0% in ISP-RI, 8% in ISP-2DE, 13% in CP-2DE and 13% in CP-DSA. The left ventricular ejection fraction (EF) was unchanged during ISP (from 65 +/- 11% to 68 +/- 12%) and it decreased both during exercise (from 64 +/- 10% to 58 +/- 9%, p less than 0.05) and during CPT (from 69 +/- 10% to 65 +/- 9%, p less than 0.05) in patients with effort angina. In patients with vasospastic angina, the EF was unchanged both during exercise (from 70 +/- 7% to 68 +/- 13%) and during the CPT (from 76 +/- 5% to 75 +/- 4%), while it increased during ISP infusion (from 63 +/- 8% to 79 +/- 7%, p less than 0.01). In patients with atypical chest pain, the EF was increased both during exercise (from 72 +/- 7% to 79 +/- 5%, p less than 0.01) and during ISP infusion (from 67 +/- 5% to 78 +/- 7%, p less than 0.01), while it was unchanged during CPT (from 77 +/- 7% to 76 +/- 8%). In exercise and in ISP infusion tests, WMA were provoked concomitantly with ST segment deviations in nearly all patients. However, during CPT, WMA were produced without the occurrence of ST segment deviations. Myocardial ischemia due to organic coronary artery stenosis was difficult to distinguish from coronary artery spasm by exercise test. However, the susceptibility to ISP infusion and CPT differed in producing WMA in patients with vasospastic angina.(ABSTRACT TRUNCATED AT 400 WORDS)
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Eighty-nine patients with carcinoma of the cervix received radical radiation therapy from May 1981 through 1983 at the hospital of the National Institute of Radiological Sciences. After a 2 to 4 year follow-up, primary cancer was found to be controlled in 59 patients, a recurrence was noted in 16 patients but 12 patients had died without precise information concerning recurrence. We examined the correlation between recurrence and seven prognostic factors. Among these factors, the tumor volume, age, and the red blood corpuscle sedimentation rate showed a relatively strong correlation. A multivariable analysis (quantification methods II) was undertaken in order to integrate these prognostic factors and the score that was calculated from this analysis showed a strong correlation to local control. We believe that this score can be used for predicting recurrences and can be applied to the selection of patients for new treatments like hyperthermia or high LET irradiation.
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In 21 patients with typical exercise-induced anginal pain but normal coronary arteriograms (group N) and in 14 patients with angiographically proved coronary stenosis (group C), symptom-limited ergometer exercise ECG and radionuclide angiocardiography were performed twice on two different days. Exercise-induced ST changes showed larger variations between the two exercise tests in group N than in group C ([delta ST1-delta ST2]: 0.07 +/- 0.06 mV in group N, 0.03 +/- 0.03 mV in group C, p less than 0.05). Rate pressure product and left ventricular ejection fraction at exercise also showed larger variations between the two tests in group N than in group C (p less than 0.001, p less than 0.05, respectively). However, substantial overlaps existed in some cases in the two groups. In conclusion, some of the patients with exercise-induced anginal pain but normal coronary arteriograms may have a variable threshold of exertional chest pain probably caused by variation in coronary vascular tone, and the other patients may have a fixed threshold of chest pain caused by other mechanisms.
Since a dynamic exercise stress test cannot always be performed adequately in elderly patients, an alternative method is needed for evaluation of coronary reserve. We studied two-dimensional echocardiographic (2-DE) and electrocardiographic (ECG) responses to infusion of isoproterenol (ISP) at a rate of 0.02 micrograms/Kg/min in 40 elderly patients with chest pain. The results were compared with exercise ECG (EX-ECG) tests and exercise radionuclide angiocardiography (EX-RNA) in 13 of these patients. No serious complications were encountered in the ISP test. The diagnostic sensitivity for coronary artery disease (CAD) was 71% for ISP-2-DE, 71% for ISP-ECG, 86% for EX-ECG and 71% for EX-RNA. The specificity for CAD was 83% for ISP-2-DE, 33% for ISP-ECG, 50% for EX-ECG and 100% for EX-RNA. In conclusion, the ISP-2-DE test is a safe, easily available and useful method for the assessment of coronary artery disease in elderly patients.