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Biomedical subjects

Y Nimura

Publications and source records attributed to Y Nimura.

At least 379 records · Page 21Linked to original sources
PubMed1984

Augmentation of atrial contribution to left ventricular inflow with aging as assessed by intracardiac Doppler flowmetry.

The influence of aging on the left ventricular (LV) function in diastole was investigated from the aspect of the mitral inflow pattern using 2-dimensional Doppler echocardiography. The subjects for the investigation were 69 persons who were diagnosed as healthy by a checkup examination. The peak velocity in the rapid filling phase and that in the atrial contraction phase tended to decrease and to increase with aging, respectively. However, these tendencies were not statistically significant. However, the ratio of the atrial contraction phase to the rapid filling phase showed a significant increase with aging (r = 0.82, p less than 0.001). Therefore, it is considered that the mitral flow conditions are influenced by aging. The result obtained is also interpreted to mean that the LV distensibility in early diastole is impaired with aging and that the contribution of the atrial contraction to LV filling is compensatorily augmented.

Adult↗
PubMed1984

3-(p-hydroxyphenyl)propionic acid as a new fluorogenic reagent for amine oxidase assays.

A detailed procedure of a new and extremely sensitive fluorometric assay for amine oxidases is presented. Hydrogen peroxide, produced by the oxidase reaction, reacted with 3-(p-hydroxyphenyl)propionic acid in the presence of peroxidase to yield a fluorescent compound by which enzyme activity could be determined. The enzyme reaction was terminated by NaOH solution, which increased the fluorescence intensity three- to fivefold. The detection limit thus obtained was as little as 0.02 nmol. The alkalinization also contributed to stopping the enzyme reaction and to the clarification of assay mixtures containing turbid enzyme preparations.

Amine Oxidase (Copper-Containing)↗
PubMed1984

Echocardiographic features of bioprosthetic valve endocarditis.

Abnormal echocardiographic findings in seven cases of bioprosthetic valve endocarditis were confirmed in six at operation. The echocardiograms showed three cases with thickening and increased echo intensity (group 1) and four (group 2) in which vegetations were seen initially without either of the two features in group 1. Two patients in group 1 had vegetations, the causative organism being a streptococcus. Staphylococcus epidermidis was the causative organism in three of the four cases in group 2; in two of these rapidly growing vegetations were detected. The large vegetations obstructed the ostium of the bioprosthetic valve. Thus if vegetations are detected in cases in which staphylococci are the causative bacteria surgery should be performed as soon as possible. In patients who develop a fever after bioprosthetic valve replacement and especially in those with evident bacteraemia echocardiography should be repeated frequently so that lesions may be detected early.

Adult↗
PubMed1984

Analysis of blood flow in pulmonary hypertension with the pulsed Doppler flowmeter combined with cross sectional echocardiography.

Blood flow patterns were analysed at nine points in the pulmonary area using the pulsed Doppler technique combined with cross-sectional echocardiography in 53 patients with heart disease and 10 healthy subjects. In subjects with a normal pulmonary artery pressure the blood flow pattern in systole showed a gradual acceleration and deceleration with a rounded summit in mid systole, designated the round type. In patients with pulmonary hypertension it showed a rapid acceleration and early deceleration with a sharp peak in early systole, designated the triangular type. The acceleration time index, defined as the ratio of the time interval from the beginning to the peak of ejection to the ejection time, showed a significant inverse correlation with mean pulmonary artery pressure. In pulmonary hypertension a prominent reverse flow occurred in the right posterior part of the pulmonary trunk during mid-systole and early diastole, indicating the presence of a vortex. Similar flow patterns were also seen in patients with idiopathic pulmonary artery dilatation. The factors responsible for the triangular type were principally the reduced capacitance and increased impedance of the pulmonary vascular tree. Those responsible for the reverse flow were the curved path of the blood flow and dilatation of the pulmonary artery.

Adult↗
PubMed1984

Doppler echocardiographic features of coronary arteriovenous fistula. Complementary roles of cross sectional echocardiography and the Doppler technique.

The Doppler echocardiographic features of coronary arteriovenous fistula were investigated in eight patients with left or right coronary arteriovenous fistulas who had a continuous heart murmur in the upper precordial area and whose diagnoses were confirmed by coronary angiography. In four patients the dilated lumen of the coronary arteriovenous fistula was visualised by cross sectional echocardiography. Of these, three showed abnormal unidirectional continuous flow signals with broad velocity spectra in the fistula. Abnormal, powerful, unidirectional or bidirectional continuous Doppler signals were detected in part of the pulmonary artery in two of the eight patients, in part of the right ventricle in two, and in part of the right atrium in one; these signals were interpreted as indicating shunt flow. Although the opening of the fistula was difficult to visualise by cross sectional echocardiography, the pulsed Doppler technique helped identify the site in patients with dilatation of the coronary artery. In the remaining three patients with a small shunt no abnormal findings were obtained with cross sectional echocardiography or the Doppler technique. The size of the fistula below which no abnormal findings may be obtained by Doppler echocardiography still needs to be determined.

Adult↗
PubMed1984

Mitral valve abnormalities in patients with right ventricular pressure overload. Analysis by real time cross sectional echocardiography.

Abnormalities of the mitral valve in patients with pulmonary stenosis, tetralogy of Fallot, and pulmonary hypertension with right ventricular pressure overload were studied by real time cross sectional echocardiography. Dislocation of the anterior and posterior mitral leaflets at the coaptation zone in systole was present in 16 of 46 cases: nine of 11 (82%) cases of pulmonary hypertension, four of 20 (20%) cases of tetralogy of Fallot, and three of 15 (20%) cases of pulmonary stenosis. The incidence was highest in patients with pulmonary hypertension. In eight of the 16 patients with mitral valve lesions, mitral regurgitation was seen on left ventriculograms or cross sectional Doppler echocardiograms. The dislocation was located near the posteromedial commissure of the anterior mitral leaflet in all cases. These findings are similar to the mitral valve abnormalities seen in patients with secundum atrial septal defect, and therefore may be due to a common cause. No relation could be found between the left ventricular deformity index and the incidence of dislocation of the mitral leaflets. Thus, the reason why this mitral valve abnormality occurs in conditions with right ventricular pressure overload could not be established.

Adolescent↗
PubMed1984

Clinical features of intracardiac thrombosis based on echocardiographic observation.

The nature of intracardiac thrombi were studied, which were the clinical underlying conditions, relation to systemic embolism, growth of thrombus and effect of anticoagulant therapy on the size of the thrombi, in 818 patients with mitral valve disease and 1000 patients with myocardial infarction by two-dimensional echocardiography. (1) Common underlying conditions were atrial fibrillation, enlarged left atrial cavity and predominance of mitral stenosis in cases with left atrial thrombi, and apical asynergy and low ejection fraction in cases with ventricular thrombi. The blood stasis should be the major factor in the formation of intracardiac thrombi. In a condition of blood stasis, dynamic intracavitary echoes which may represent erythrocyte aggregation were observed. (2) The incidence of systemic embolism in patients with thrombi was higher than that in patients without thrombi in cardiac disease. (3) The intracardiac thrombi were living. They grew and/or reduced their size spontaneously and sometimes became detached from the cardiac wall in the form of ball thrombi. (4) The effect of anticoagulant therapy on the regression of thrombi depends on its age.

Adult↗
PubMed1984

[Noninvasive determination of the ratio of pulmonary to systemic blood flow with two-dimensional Doppler echocardiography: efficacy and limitation].

Noninvasive determination of the ratio of the pulmonary to systemic blood flow (Qp/Qs) was attempted in 31 cases with intracardiac shunt using two-dimensional pulsed Doppler echocardiography. The Qp/Qs of these cases was ranged from 0.99 to 4.55 with an average of 2.63 by cardiac catheterization. Technical problems in the measurement were also studied. Seventeen cases with no shunt were served as controls. Systemic and pulmonary flow volumes, Qp and Qs (ml/min), were calculated by the following equation: Q (ml/min) = mean flow velocity (cm/sec) X cross sectional area of the semilunar valve ring (cm2) X 60 Here, the sample volume was set in the center of the valve ring at the phase when the flow velocity attained its peak in a pulse period. The mean velocity was obtained by dividing the integration of instantaneous mean frequency in the sample volume for a pulse period by RR interval. The ultrasonic incident angle was measured on the echocardiogram. The velocity profile at the valve ring was assumed to be a plane wave. The diameter (D) of the valve ring was measured on the echocardiograms of the long-axis view of the outflow tract. To make a correction referring to the value obtained by angiocardiography, 0.22 cm was added to the value obtained on the echocardiogram (D). The cross sectional area of the valve ring was calculated according to the following formula: Cross sectional area (cm2) = pi X [(D + 0.22/2)]2 The Qp/Qs ratio by the Doppler method in the cases with no intracardiac shunt was 1.11 (S.D. = 0.21) on an average and the Qp/Qs in the cases with an intracardiac shunt was well correlated with that by catheterization (r = 0.82). These results suggested the feasibility of the clinical application of the Doppler method for noninvasive determination of Qp/Qs. In 17 cases, pulmonary and systemic flow volumes measured by the direct Fick method were compared with those by the Doppler method, respectively. Considerable differences were observed between them. There was a tendency that both pulmonary and systemic flow volumes were under-estimated by the Doppler method in cases with a large shunt.(ABSTRACT TRUNCATED AT 400 WORDS)

Blood Circulation↗
PubMed1984

[Mitral valve lesions in patients with right ventricular pressure overload: analysis using realtime, two-dimensional echocardiography].

Mitral valve lesions in patients with right ventricular pressure overload, such as pulmonary stenosis, tetralogy of Fallot, and pulmonary hypertension, were studied by real-time, two-dimensional echocardiography, and the following results were obtained. The abnormality observed in the mitral valve was a systolic dislocation of the anterior and posterior mitral leaflets at the coaptation zone. Mitral valve lesions were noted in 16 of 46 cases, i.e. nine of 11 with pulmonary hypertension (82%), four of 20 with tetralogy of Fallot (20%), and three of 15 with pulmonary stenosis (20%). The incidence was highest in patients with pulmonary hypertension. In eight of 16 cases with mitral valve lesions, mitral regurgitation was observed by either left ventriculography or two-dimensional Doppler echocardiography. Mitral valve lesions were always located at the posteromedial commissure of the anterior mitral leaflet. Considering the previous similar reports in secundum atrial septal defect, we attributed the cause of the mitral valve lesions to the same mechanism. No clear relation could be found between the left ventricular deformity index and the incidence of mitral valve lesion. Therefore, we could not conclude about the mode of production of mitral valve lesions occurring in the diseases with right ventricular pressure overload.

Adolescent↗
PubMed1984

[Ventricular interdependence reflected in interventricular septal motion: with special reference to right ventricular pressure overload].

The dynamic features of the interventricular septum were studied with two-dimensional echocardiography with special reference to the influence of right ventricular (RV) pressure overload. The subjects were 52 patients, including 30 with atrial septal defect (ASD), 14 with rheumatic mitral valvular disease and 8 with pulmonary hypertension (PH) due to cor pulmonale, pulmonary embolism, or primary PH. To assess septal motion, the configuration of the left ventricle (LV) in the short-axis view was quantified as the deformity index, and characterized as the distortion from right circle. As an accurate short axis was required to assess the deformity of the cavity, the transducer was attached to the guide arm, providing comparable positions and directions. The deformity index was highest at the chordal level among other levels in the same cardiac phase. In ASD without PH, the deformity was minimal in end systole and maximal in early diastole. The index curve showed two peaks in early diastole and these times coincided with those of the minute backward notches on the ventricular septal echogram. In ASD with PH, the deformity was minimal in early systole and became greater during systole. The maximum deformity was shown in early diastole, corresponding to the momentary retracting motion of the septum by M-mode echocardiography. At that moment, the septum became convex to the LV. In patients with RV pressure overload, the systolic peak of the RV pressure was delayed and the decrease in pressure became sluggish, resulting in the RV pressure exceeding that of the LV transiently in early diastole. This was the reason for the septum becoming convex to the LV in this phase. Among the patients, the bi-ventricular systolic pressure ratio correlated not only with the index in end systole but also with that in early diastole. Good correlation between systolic pressure ratio and early diastolic deformity index seemed to be attributable to the fact that the higher the RV systolic pressure, the larger the reversed pressure gradient between both ventricles in early diastole.(ABSTRACT TRUNCATED AT 400 WORDS)

Diastole↗