Differentiation between acute and healed myocardial infarction by signal averaging and color encoding two-dimensional echocardiography

Abstract

To evaluate the ability of a system developed in our laboratory to differentiate between acute and healed myocardial infarction (MI), gated 2-dimensional echocardiography was performed in 10 patients with recent MI (within 48 hours) and 10 patients with healed MI (later than 4 weeks). The 2-dimensional echocardiographic images were digitized using a Datacube VG-120 videoframe digitizer and each digitized videoframe (320 × 240 matrix) was transmitted using a high-speed serial data link to a second computer and stored on floppy disc. Five gated video frames of each patient were time-averaged to give a smoothed digitized image. This image was displayed on high-resolution color monitor connected to a color graphic subsystem. Sixty-four colors indicated pixel intensity. The exact pixel value at any given location was determined using a high-resolution light pen. Color or pixel values were not significantly different between the area of acute MI (pixel intensity 23 ± 3, mean ± standard deviation) identified by a regional wall motion abnormality, and the adjacent normal muscle (23 ± 4). In each patient with healed MI, an increase in color intensity and pixel value (43 ± 6) was seen in the area of MI (i.e., area of regional wall motion abnormality) compared with adjacent normal muscle (23 ± 2) (p < 0.001). These preliminary data in selected patients indicate that this technique enables differentiation between acute and healed MI. It could be of value in management of patients with suspected MI.