Development of the method quantitatively to assess regional left ventricular function using high-frame-rate echocardiography.

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Because many heart diseases are constituted regional rather than global abnormalities of the left ventricle and because left ventricular diastolic function is impaired prior to systolic function in patients with heart diseases, measures of regional left ventricular dysfunction, if possible, should provide most sensitive assessment of the involved region. We made a new system by combining high frame rate two-dimensional echocardiography with a digital subtraction image processing to visualize regional abnormalities of the left ventricle and examined whether this technique provides a measure for the noninvasive assessment of coronary involved region in patients with ischemic heart disease. Two-dimensional echocardiograms obtained at a rate of 60 frames/sec were provided on line for digital subtraction analysis with which digitized images were continuously subtracted on the frame-by-frame basis. The subtracted images were analyzed to determine the onset of the segmental outward motion of the left ventricular wall in early diastole in each of 16 segments per subject. Relaxation index, which was defined as the interval from the second heart sound to the onset of outward wall motion in each segment, was significantly prolonged in the coronary involved segments as compared to the normal segments (P<0.01). The prolongation in the relaxation index was associated with ventriculographic index of regional relaxation (r=0.61, P<0.01). Thus, digital subtraction high frame rate echocardiography may be used semi-quantitatively to assess regional abnormalities of left ventricular relaxation in patients. Time interval from the second heart sound to the onset of the segmental outward motion of the left ventricular wall (relaxation index), obtained with this technique, provides a noninvasive and accurate measure for assessing coronary involved regions.