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

由于许多心脏病是由左心室的局部而非整体异常构成的，并且由于心脏病患者的左心室舒张功能先于收缩功能受损，因此，如果可能的话，局部左心室功能障碍的测量应提供对所涉及区域的最敏感的评估。我们将高帧频二维超声心动图与数字减影图像处理技术相结合，建立了一种新的系统，以显示左心室的局部异常，并探讨该技术是否为缺血性心脏病患者冠状动脉受累区域的无创评估提供了一种方法。以60帧/秒的速率获得的二维超声心动图在线提供用于数字减影分析，其中数字化图像在逐帧的基础上连续减影。分析减影图像，以确定每个受试者16个节段中每一个节段的左室壁在早期舒张期的节段性向外运动的开始。舒张指数（从第二心音到各节段室壁运动开始的时间）在冠状动脉病变节段较正常节段显著延长（P<0.01）。舒张指数延长与心室造影局部舒张指数相关（r=0.61，P<0.01）。因此，数字减影高帧率超声心动图可以半定量地用于评估患者左心室舒张的局部异常。从第二心音到左室壁节段性向外运动开始的时间间隔（舒张指数），用这种技术获得，为评估冠状动脉受累区域提供了无创和准确的测量。

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.