Role of intra-ventricular vortex in left ventricular ejection elucidated by echo-dynamography.

Purpose: From the correlation between the blood flow dynamics and wall dynamics in the left ventriocle (LV) analyzed using echo-dynamography, the ejection mechanisms and role of the intra-ventricular vortex in the LV were elucidated in detail during the pre-ejection transitional period (pre-ETP), the very short period preceding LV ejection.

Methods: The study included 10 healthy volunteers. Flow structure was analyzed using echo-dynamography, and LV wall dynamics were measured using both high-frame-rate two-dimensional echocardiography and a phase difference tracking method we developed.

Deformability of the pulsating left ventricular wall: A new aspect elucidated by high resolution ultrasonic methods.

Background: Although the deformability of the left ventricular (LV) wall appears to be important in maintaining effective cardiac performance, this has not been debated by anyone, probably owing to the difficulties of the investigation.

Objectives: This study applies a new technology to demonstrate how the LV wall deforms so as to adjust for optimum cardiac performance.

Subjects And Methods: Ten healthy volunteers were the subjects.

Non-uniform distribution of the contraction/extension (C-E) in the left ventricular myocardium related to the myocardial function.

Objective: We attempted to disclose the microscopic characteristics of the non-uniform distribution of the contraction and extension (C-E) of the left ventricular (LV) myocardium using a new methodology (echo-dynamography).

Methods: The distributions of the "axial strain rate" (aSR) and the intra-mural velocity in the local areas of the free wall including the posterior wall (PW) and interventricular septum (IVS) were microscopically obtained using echo-dynamography with a high accuracy of 821 μm in the spatial resolution. The results were shown by the color M-mode echocardiogram or curvilinear graph.

New concept of the contraction-extension property of the left ventricular myocardium.

Objectives: Using newly developed ultrasonic technology, we attempted to disclose the characteristics of the left ventricular (LV) contraction-extension (C-E) property, which has an important relationship to LV function.

Methods: Strain rate (SR) distribution within the posterior wall and interventricular septum was microscopically measured with a high accuracy of 821μm in spatial resolution by using the phase difference tracking method. The subjects were 10 healthy men (aged 30-50 years).

Physiological basis and clinical significance of left ventricular suction studied using echo-dynamography.

Background: The existence as well as the exact genesis of left ventricular suction during rapid filling phase have been controversial. In the present study, we aimed at resolution of this problem using noninvasive and sophisticated ultrasonic methods. The clinical meaning was also documented.

Spiral systolic blood flow in the ascending aorta and aortic arch analyzed by echo-dynamography.

Using echo-dynamography, systolic blood flow structure in the ascending aorta and aortic arch was investigated in 10 healthy volunteers. The blood flow structure was analyzed based on the two-dimensional (2D) and 1D velocity vector distributions, changing acceleration of flow direction (CAFD), vorticity distribution, and Doppler pressure distribution. To justify the results obtained in humans, in vitro experiments were done using straight and curved tube models of 20mm diameter.

Blood flow structure and dynamics, and ejection mechanism in the left ventricle: analysis using echo-dynamography.

Using our "echo-dynamography", blood flow structure and flow dynamics during ventricular systole were investigated in 10 normal volunteers. The velocity vector distribution demonstrated blood flow during ejection was laminar along the ventricular septum. The characteristic flow structure was observed in each cardiac phases, early, mid- and late systole and was generated depending on the wall dynamic events such as peristaltic squeezing, hinge-like movement of the mitral ring plane, bellows action of the ventricle and dimensional changes in the funnel shape of the basal part of the ventricle, which were disclosed macroscopically by using the new technology of high speed scanning echo-tomography and microscopically by the strain rate distribution measured by phase tracking method.

Effects of Dobutamine Infusion on Mitral Regurgitation.

Both intensity of mitral regurgitant murmur and color-coded Doppler regurgitant signal area have been reported to correlate with the degree of regurgitation. To evaluate the relationship between the intensity of regurgitant murmur and severity of mitral regurgitation, phonocardiography, echocardiography, and Doppler ultrasound were performed in 18 patients with mitral regurgitation before and during dobutamine infusion. Mitral regurgitation was due to mitral valve prolapse with ruptured chordae tendineae in 8 patients, rheumatic change in 5 patients, and dilated cardiomyopathy in 5 patients.