Background and Purpose. It is not easy to evaluate blood inflow into the myocardial microvasculature. The purposes of this study were to visualize inflow to the microvasculature using real-time myocardial contrast echocardiography (MCE) and to examine the effects of cardiac phase on the replenishment curve. Methods and Results. Real-time MCE was performed during Definity® infusion in 6 open- canines. The timing of termination for the burst technique was set at end-diastolic or end-systolic phase, and the initial inflow of contrast after destruction of bubbles into the myocardium was evaluated. The video intensity at ventricular septum was also measured until myocardial opacification reached a plateau after the burst technique and was fitted to the replenishment curve: y=A(1-e -βt). Results. Myocardial opacification at diastolic phase just after destruction of bubbles significantly increased, however, it did not increase in the initial systolic phase. The A value did not change regardless of timing of termination to burst bubbles. The β value at diastolic phase was lower than that at systolic phase (0.91±:0.18 vs. 0.67±0.14). Conclusions. The flow into coronary arterioles is dominant at diastolic phase similar to epicardial coronary flow. Timing of termination to burst bubbles influences parameters of replenishment curve.
Background. It is reported that hyperlipidemia may deteriorate the coronary circulation by itself. The aim is to examine the effect of acute hypertriglyceridemia on myocardial perfusion using real-time myocardial contrast echocardiography (MCE). Methods. Hypertriglyceridemia was induced by infusion of fat emulsion (Intralipos) in 7 open-chest dogs. The coronary flow was measured by a flow meter, and its reserve (CFR) was determined by adenosine triphosphate (ATP) injection. MCE was examined using SIEMENS Sequoia-512 during infusion of Definity®. The replenishment curve was obtained to measure the A and β value in the equation of y=A(1-e-βt). Results. The β value did not change by hyperlipidemia, however, its increment by ATP decreased significantly at hyperlipidemia. The β value after ATP decreased concomitantly with the increase of both serum triglyceride level and blood viscosity. However, the A value was not affected by either serum triglyceride or viscosity. Conclusions. Hypertriglyceridemia makes blood viscous followed by high shear stress in the resistant vessels. Although myocardial resistant vessels are dilated for its compensatory response, exaggeration of blood flow speed in the capillaries after ATP is impaired due to high viscosity of hyperlipidemia.
Objectives. The purpose of this study was to determine whether the assessment of mitral annulus displacement (MAD) using Doppler-tissue image (DTI) could provide a useful marker of heart failure severity. [Methods] In seventy-five subjects with heart diseases, we measured MAD by tissue-tracking method with DTI. MAD was evaluated in both septal and lateral corners of the mitral annulus in the apical 4-chamber view, and the degree of MAD in postsystolic phase was estimated as a ratio of displacement at aortic valve closure and peak point (P/A ratio). We divided subjects into three groups (group A: subjects with preserved MAD, group B: subjects with reduced MAD without increasing P/A ratio, group C: subjects with reduced MAD with increasing P/A ratio) and compared NYHA functional class and left ventricular ejection fraction (LVEF). Results. NYHA functional class and LVEF were significantly different among the three groups (NYHA functional class; group A: 1.2±0.4, group B: 2.3±0.9, group C: 3.1±0.8, LVEF; group A: 58±12 %, group B: 42±15 %, group C: 25±8 %). These results indicated that MAD which represents mainly LV longitudinal function is decreased in the first place, and then, post-systolic displacement is exaggerated according to the severity of heart failure. Conclusions. The classification of the degree and timing of peak MAD (P/A ratio) is well correlated with NYHA functional class and LVEF and becomes one of the useful indexes of heart failure severity.
Background. Mitral valve prolapse is defined by two-dimensional (2D) echocardiography as an existence when the leaflet exceeds the annular level. However, the annular level set by 2D echocardiography differs in each view because of the "saddle-shape" of the annulus. In this study, we sought to investigate the degree of mitral valve prolapse from the three-dimensional (3D) dataset, which was created by the newly developed quantitative software system with transthoracic real-time 3D echocardiography, and then compare the data with normal subjects. Methods. Thirteen patients with mitral valve prolapse who were planned to have mitral valve repair (anterior leaflet, 6 patients; posterior leaflet, 7) and 21 healthy subjects were studied. Echocardiographic exams were performed by SONOS 7500 with X4 probe before surgery. Transthoracic volumetric images (full-volume mode) were obtained from the apical view. A newly developed software was used to crop the 3D data, and the mitral annulus and leaflets were traced in each cropped image. 3D images of the mitral leaflets and annulus were then automatically reconstructed for 3D quantitation. Prolapsed leaflet area was defined as the region that exceeded estimated 3D mitral annular level into the left atrium. We analyzed the % prolapsed area (ratio of the prolapsed leaflet area to the mitral annular area), and the maximum prolapse height from the 3D annular level to the maximum prolapsed site. Results. In patients with mitral valve prolapse, % prolapsed area was 20.9±5.8% (anterior 22.5±7.3%, posterior 19.4±4.0%). Maximum prolapse height was 8.4±5.8mm (anterior5.7±2.7mm, posterior10.7±6.9mm). In 16 of 21 healthy subjects, a small degree of prolapse was seen in the middle portion of the anterior scallop (% prolapsed area was 7.96±6.94%, p<0.001, maximum prolapse height was 1.8±1.7mm, p<0.001 vs. mitral valve prolapse). Conclusions. Mitral valve prolapse could be quantitatively assessed by newly developed software system with real-time 3D echocardiography. Investigation of new standard of mitral valve prolapse in 3D insights would be required.
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