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Biomedical subjects

A Kitabatake

Publications and source records attributed to A Kitabatake.

At least 289 records · Page 16Linked to original sources
PubMed1979

A new modulation method with range resolution for ultrasonic Doppler flow sensing.

This paper proposes a new pair of sequences whose cross-correlation values are zero except for the peak value and presents a new modulation method for an ultrasonic Doppler flowmeter with high sensitivity utilizing these sequences. In this method, transmitted and received waves are modulated and demodulated, respectively, by the specified new sequences. Since ulfavourable reflected waves can be almost completely eliminated by this proposed modulation method, a high signal-to-noise ratio is easily achieved. Elementary experimental results are also given.

Doppler Effect↗
PubMed1978

Diastolic stress-strain relation of nonexcised blood-perfused canine papillary muscle.

We studied diastolic stiffness of 10 coronary-perfused twitching papillary muscles of the canine right ventricle. The muscle beat at a regular sinus rhythm of 122 +/- 20 (SD) beats/min at 37 degrees C. They were stretched slowly at a constant rate. Diastolic force increased exponentially with the stretch. Calculating Lagrangian stress (sigma) and strain (epsilon) from diastolic force and length, we found a linear relationship between ln sigma and epsilon within the physiological range of strain (0.025 less than epsilon less than 0.4). This indicates that the diastolic stress-strain relationship of the canine papillary muscle can be approximated by a single exponential curve: sigma = a.exp(b.epsilon). The mean +/- SD of the stiffness constant b was 18.0 +/- 3.2 (dimensionless). Our b values are comparable to those of dogs and human subjects, either indirectly assessed from the ventricular pressure-volume relationship or directly obtained in excised quiescent muscle specimens. Different coronary perfusion pressures (75-125 mmHg) in 10 muscles showed a statistically significant positive correlation to b values.

Animals↗
PubMed1977

Intracardiac flow dynamics with bi-directional ultrasonic pulsed Doppler technique.

1) Intracardiac flows were investigated by bi-directional pulsed Doppler technique with a combined use of the two-dimensional echocardiography. The flow at sampling sites in the heat and great vessels were correctly identified on the two-dimensional echocardiograms. 2) Soundspectrographic analysis of the flow Doppler signals was useful in obtaining information about flow modes and in differentiating flow signals from those of valves. 3) In healthy subjects, intracardiac flow revealed a laminar mode. As a matter of interest, a flow toward the aorta, which is a cranially turned flow, was found at the center and at the outflow tract of the left ventricle from mid to late diastole. 4) In mitral stenosis, the central stream at the stenotic portion exhibited an almost laminar and rapid flow. A good coincidence in flow mode was observed between clinical cases of mitral stenosis and experimental stenosis. 5) Disturbed flows were observed in the following diseased conditions. The diastolic regurgitant flow in the left ventricular outflow tract and mitral inflow in aortic regurgitation, the regurgitant flow into the left atrium and the diastolic mitral inflow in mitral regurgitation, the ejection flow in hypertrophic cardiomyopathy with outflow tract obstruction, and the tricuspid inflow in atrial septal defect. 6) Mechanisms of intracardiac flow dynamics were also discussed.

Adolescent↗