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Biomedical subjects

R Ajisaka

Publications and source records attributed to R Ajisaka.

At least 55 records · Page 3Linked to original sources
PubMed1989

Evaluation of myocardial perfusion abnormality by profile analysis for digital subtraction angiogram.

For quantitative estimation of ischemia, ECG-synchronized digital subtraction angiography was performed for selective coronary arteriography. The authors obtained sequential myocardial perfusion images at the arterial, capillary, and venous phases. Profile densitometry was performed along the cross section perpendicular to the long axis of the left ventricle to assess regional myocardial perfusion at the capillary phase quantitatively. By this densitometry, the volumes of vascular bed perfused by the left coronary artery could be estimated, and further, nontransmural myocardial infarction could be differentiated from transmural myocardial infarction through the profile of its density curve. This method appears to be useful for the analysis of myocardial perfusion of ischemic heart disease.

Adult↗
PubMed1989

Effect of nifedipine on left ventricular function during exercise in patients with stable effort angina. Relation of its efficacy to the severity of coronary artery disease.

To evaluate whether the effect of nifedipine on left ventricular function relates to the severity of coronary artery disease (CAD) or not, supine graded ergometer exercise testing was performed before and after sublingual administration of 10 mg nifedipine in 24 patients with stable effort angina. To minimize the effect of nifedipine on myocardial oxygen consumption, exercise before and after nifedipine was discontinued at the same target rate pressure product. Percent (%) left ventricular ejection fraction (EF) [EF during exercise/EF at rest.100] was measured before and after nifedipine by radionuclide angiocardiography. The angiographic degree of CAD was defined by Gensini's CAD scoring as follows: severe CAD: greater than or equal to 50, moderate: less than 50 greater than 20 and mild: less than or equal to 20. After nifedipine, left ventricular function (%EF) was improved in all 6 patients with mild CAD, but was worsened in all 9 patients with severe CAD. Maximal ST segment depression during exercise was improved in 5 of 6 patients with mild CAD, while improvement was induced in 5 of 9 patients with moderate CAD and in 3 of 9 patients with severe CAD. Jeopardy of coronary collateral vessels may have an influence on the effect of nifedipine. It is suggested that the effect of nifedipine on left ventricular function is influenced by the severity of CAD when most of its effect on myocardial oxygen consumption is eliminated.

Adult↗
PubMed1989

The significance of abnormal systolic blood pressure response during supine ergometer exercise and postexercise in ischemic heart disease, studied by exercise radionuclide ventriculography.

The prognostic value of abnormal postexercise systolic blood pressure (BP) response has not been investigated. Therefore, the significance of abnormal BP response during exercise and postexercise was examined in 169 patients with ischemic heart disease subjected to supine ergometer exercise gated equilibrium radionuclide ventriculography, coronary arteriography, and follow up averaging 3.6 years. Abnormal BP response during exercise (exertional "hypotension") was defined as 1) a failure of BP to rise by at least 11 mmHg or 2) an initial rise in BP but subsequent fall by more than 10 mmHg during exercise. Abnormal BP response during postexercise (postexercise "hypertension") was defined as an increase of more than 10 mmHg above the peak exercise BP. Of 169 patients, 51 (30%) had an abnormal BP response. Four types of BP response were identified: exertional "hypotension" (group 1a, n = 11), postexercise "hypertension" (group 1b, n = 30), exertional "hypotension" with postexercise "hypertension" (group 1c, n = 10) and normal BP response (group 2, n = 118). Both average exercise duration and peak heart rate were significantly lower in groups 1a, 1b and 1c than in group 2. The severity of exercise ST-segment depression was greater in groups 1b and 1c than in group 2. However, there was no significant difference in the severity of exercise ST-segment depression between group 1a and group 2. A decline in ejection fraction occurred more frequently in groups 1b and 1c than in group 2. Patients in groups 1a, 1b and 1c had more extensive coronary artery disease (CAD) than did patients in group 2. Medically treated patients with an abnormal BP response (groups 1a, 1b and 1c) had a poorer prognosis than did those with a normal BP response (group 2). These findings suggest that an abnormal BP response during supine exercise is infrequent, but is usually associated with impaired exercise tolerance and severe CAD. An abnormal postexercise BP response is also infrequent, but is more closely associated with evidence of myocardial ischemia and global left ventricular dysfunction than exertional "hypotension". In conclusion, postexercise "hypertension" has the same value as exertional "hypotension" as a predictor of poor prognosis.

Angina Pectoris↗
PubMed1989

Isoproterenol stress thallium scintigraphy for detecting coronary artery disease.

The value of exercise thallium scintigraphy in detecting coronary artery disease is well established. However, there are at times situations in which the exercise test cannot be readily used. Isoproterenol (ISP) stress ECG (ISP-ECG) is reportedly a useful method in diagnosing coronary artery disease. In the present study, we assessed the diagnostic value of ISP thallium scintigraphy, comparing it with those of ISP-ECG and exercise thallium scintigraphy. The study population consisted of 24 patients who had histories of chest pain without previous myocardial infarction. ISP was given at increasing doses of 0.02, 0.04, 0.08 micrograms/kg/min at 3-minute intervals, and was terminated for any of the following reasons: angina, significant arrhythmia, significant ST segment depression (greater than or equal to 0.1 mV) or target heart rate. Thallium scintigrams were obtained immediately after terminating ISP infusion, and after a 3-hour delay, redistribution scans were obtained. Scintigrams were considered positive when a reversible defect was present. In nine patients who underwent exercise tests, exercise thallium scintigraphy was also performed. After the stress tests, coronary angiography was performed. According to the presence or absence of significant coronary artery stenosis (greater than or equal to 75%), all subjects were divided into two groups: coronary artery disease (CAD) group (n = 12) and so-called normal coronary (NC) group (n = 12). 1. Among 12 patients in the CAD group, ISP induced anginal pain in six (50%), and ISP-ECG and ISP thallium scintigraphy were positive in 10 (83%) and in 11 (92%), compared with four (33%), four (33%) and two (17%) in the NC group.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

[New trends in diagnostic examinations in clinical cardiology].

There are various kinds of diagnostic examinations in the field of clinical cardiology. In this field, information concerning cardiac structure, dimensions (hypertrophy and dilatation) and cardiac functions are inevitably important. Noninvasive methods are desirable. Except for radiological examinations, electrocardiography and ultrasonic echocardiography are 2 main examinations in cardiology. Holter monitoring is one of the recent topics in clinical electro-cardiology. It is useful for the detection of rest angina or variant angina. Recently "silent myocardial ischemia" has been studied by using this method. This method is also useful for the study of arrhythmia, which is a major cause of sudden death. Quantitative analysis of arrhythmia in the studies of antiarrhythmic drugs can also be done by Holter monitoring. Late potential is also a topic in electro-cardiology. Ultrasonic echocardiography can detect the changes of cardiac structure and function. Doppler echocardiography, developed recently, has made it possible to estimate intracardiac pressure (especially pulmonary arterial pressure) noninvasively. With esophageal echocardiography findings in left atrium, such as thrombus or myxoma in left atrium can be obtained. The most appropriate tool must be selected from the many kinds of diagnostic examinations for efficient clinical diagnosis and therapy.

Echocardiography↗
PubMed1988

Tricuspid regurgitation diagnosed by intravenous digital subtraction angiography.

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.

Adult↗
PubMed1988

Sudden death in hypertrophic cardiomyopathy, a guideline to prevention in daily life.

To establish guidelines for individuals with hypertrophic cardiomyopathy (HCM) to follow in their daily lives and minimize the chance of sudden death (SD), circumstances of SD in 24 autopsied definite HCM cases were compared with those with 905 autopsied cases of other heart diseases. Circumstances of symptoms experienced in daily activities of 35 age-matched surviving HCM cases were also studied. In the autopsied HCM cases, SD occurred during exertion more frequently (79.2%) than in the other autopsied cardiac patients (22.7%). Sudden changes in pace or movement accompanied by mental excitement, such as hurrying to board a train, were more frequent causes of SD in HCM (47.4%) than in other cardiac patients (8.3%). In the surviving HCM cases, symptoms of distress occurred frequently during very hard work or with sudden rapid movement. Thus, one probable daily guideline for HCM sufferers would appear to be not only to eliminate very hard work but also to lead mentally and physically quiet and relaxed life.

Adolescent↗
PubMed1987

Variable neurohumoral and hemodynamic responses to exercise in patients with exertional angina: influence of the severity of coronary artery disease.

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.

Angina Pectoris↗
PubMed1987

Effects of nifedipine on left ventricular systolic and diastolic function in patients with ischemic heart disease. Radionuclide angiocardiographic studies at rest and during exercise.

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.

Coronary Disease↗
PubMed1987

[Comparative sensitivities of exercise, isoproterenol infusion and cold pressor tests for detecting myocardial ischemia].

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)

Cold Temperature↗
PubMed1986

Difference in the response to isoproterenol between asymmetric septal hypertrophy and symmetric hypertrophy in patients with hypertrophic cardiomyopathy.

The response to isoproterenol was studied in 9 patients with hypertrophic cardiomyopathy (HCM) and asymmetric septal hypertrophy (ASH), 9 patients with HCM and symmetric hypertrophy (SH), and 9 normal controls (NC), using digitized M-mode echocardiography. There was no significant difference in fractional shortening (FS) between ASH and SH, nor between SH and NC before isoproterenol infusion. During isoproterenol infusion, however, FS was significantly greater in ASH (60 +/- 6%) than in SH (53 +/- 7%) and NC (49 +/- 5%) (p less than 0.05, p less than 0.01, respectively), and normalized peak rate of change of left ventricular dimension during systole (pVs) was greater in ASH (7.7 +/- 1.5/s) than in SH (5.2 +/- 0.8/s) and in NC (4.9 +/- 0.8/s) (p less than 0.001, p less than 0.001, respectively). This study shows that the response to isoproterenol of ASH differs from those of SH and of NC and suggests hypersensitivity of the beta-adrenergic receptor system in ASH and the possibility that ASH is a different clinical entity than SH.

Cardiomyopathy, Hypertrophic↗
PubMed1986

Daily variations of ECG and left ventricular parameters at exercise in patients with anginal attacks but normal coronary arteriograms.

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.

Adult↗
PubMed1986

Isoproterenol infusion stress two-dimensional echocardiography in diagnosis of coronary artery disease in elderly patients. Comparison with the other stress testing methods.

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.

Aged↗
PubMed1986

Quantitative analysis of left ventricular function by cold pressor two-dimensional echocardiography in patients with coronary artery disease.

Quantitative assessment of left ventricular function in patients with coronary artery disease was made by computer analysis of two-dimensional echocardiography performed during a cold pressor test. Short-axis cross-sectional images of the left ventricle at the levels of the mitral valve and chordae tendineae were recorded by a phase array sector scanner in 12 patients with coronary artery disease and 11 normal controls. Endocardial outlines at end-diastole and end-systole were traced and analyzed by a computer system. The short-axis cross-sectional images were divided into octants and were analyzed. The segmental area and its changes during the cardiac cycle were measured and calculated for each octant. Regional function of the left ventricle was evaluated by percent changes of segmental area. The regional segmental area changes in patients with coronary artery disease were compared with those in normal controls. Similar increments were achieved in rate pressure product in the 2 groups. In relation to the perfusing coronary arteries, 8 segments were integrated arbitrarily into 3 walls (anteroseptal wall, lateral wall, and posterior wall and posterior septum). The cold pressor test induced wall motion abnormalities in 12 of 16 walls which were supplied by stenosed coronary arteries. In contrast, wall motion abnormalities were detected in only 5 of 38 walls which were supplied by coronary arteries without significant stenotic lesions. The sensitivity of cold pressor test-induced wall motion abnormalities in detecting coronary artery disease was 75% and the specificity was 87%. No serious complications were encountered in this study. In conclusion, computer-aided cold pressor two-dimensional echocardiography is a safe and sensitive method for the assessment of left ventricular function and diagnosis of coronary artery disease.

Adult↗
PubMed1986

Clinical validity of washout time constant images obtained by digital subtraction angiography.

Functional images of left ventricular myocardial perfusion were obtained using the washout time constant obtained from the analysis of digital subtraction angiograms (DSA). The results were compared with those of left ventriculography to evaluate its clinical validity. DSA examinations were performed in eight patients with old anterior myocardial infarction and in 10 control subjects. Washout time constant images of the left ventricular wall were nearly homogeneous in normal cases. On the contrary, regional heterogeneity on the washout time constant images was observed in cases of anterior infarction. The abnormal region in the washout time constant image corresponded well to the area of abnormal percent wall thickening, whereas the extent of the abnormal wall motion area tended to be broader than that of the abnormal washout time constant area or area of abnormal percent wall thickening. Thus, the washout time constant images obtained by DSA may comprise a reliable means of estimating the extent of ischemia in the myocardium.

Aged↗