Taizo Matsuyama

Three-dimensional reconstruction of echocardiograms based on orthogonal sections

Abstract In order to obtain three-dimensional ultrasound images of the heart, a scanner with easy operation is required. This paper describes a three-dimensional cardiac imaging method with motion based on orthogonal sectional images. These original sectional images may be taken by a transesophageal approach using two miniature phased array transducers mounted on the tip of a gastroscope or simultaneous bi-frequency method using two mechanical scanning transducers set on the thorax. The latter scanner is now commercially available. Images are recorded on video tapes. Contour curves of 2-D echocardiograms are extracted and reconstructed as a 3-D moving heart image. The cardiac volume curve vs. time is also evaluated based on these three-dimensional data.

Plan-based boundary extraction and 3-D reconstruction for orthogonal 2-D echocardiography

Abstract This paper describes an automatic boundary extraction method from 2-D echocardiograms and 3-D reconstruction based on the extracted boundary lines. We use an orthogonal 2-D echocardiography which has two probes with different frequencies and can take two sectional cardiac ultrasound images simultaneously. When we extract the boundary lines, we use plans to reduce the processing time and to interpolate the boundary of no echo area.

Predominantβ-adrenoceptor blocking effect of xamoterol averaged over the day in patients with mild to moderate heart failure: insight into the mechanism of its long-term clinical efficacy

SummaryXamoterol acts as aβ1-adrenoceptor agonist at low sympathetic activity and as an antagonist at high activity. Although its long-term efficacy has been proven in patients with mild to moderate heart failure, it remains unclear which effect, agonism or antagonism, accounts for its long-term activity.To clarify the effect of xamoterol on cardiac sympathetic activity in daily life, 24-h R-R interval histograms were obtained during administration of xamoterol 100 mg b. d. for 1 week to 10 patients with mild to moderate heart failure. Eight normal subjects were also studied as controls. To examine the relation between the effect of xamoterol and sympathetic activity, plasma noradrenaline (NA) levels were measured under 5 graded conditions simulating daily living.Xamoterol administration significantly decreased the standard deviation of the R-R interval, both in patients with heart failure and in normal subjects. The mean R-R interval, however, was increased in patients with heart failure, relative to normal subjects.In both groups, the R-R interval histograms had two peaks, i. e. a short daytime peak and a long night-time peak. Xamoterol decreased the median of the night-time peak without changing the daytime peak in normal subjects. In contrast, it increased the median of the daytime peak without producing a significant change in the nighttime peak in patients with heart failure. Levels of plasma NA were significantly higher in patients than in normal subjects under all conditions.Thus, in normal subjects xamoterol predominantly increased the slower heart rate at night with only a minor effect on the higher heart rate in the daytime, whereas it predominantly attenuated the daytime tachycardia induced by sympathetic stimulation in patients with heart failure.It is concluded that xamoterol tends overall to act as aβ-adrenoceptor antagonist during the day, especially in the daytime in patients with mild to moderate heart failure. Its antagonist rather than its agonist effect may account for the long-term efficacy of xamoterol in patients with mild to moderate heart failure.