[Computer analysis of wo-dimensional echocardiogram for the quantitative evaluation of left ventricular asynergy in myocardial infarction].

Quantitative assessment of left ventricular asynergy in myocardial infarction was made by computer analysis of the two-dimensional echocardiogram. Short-axis cross-sectional images of the left ventricle at the levels of the mitral valve, papillary muscle and apex were recorded by a phased array sector scanner in 20 patients with myocardial infarction and ten normal controls. End cardial and epicardial outlines at end-diastole and end-systole were traced and analyzed by a computer system. Short-axis cross-sectional images of the left ventricle were divided equally into octants and analyzed with a fixed external reference system, using the center of gravity of end-diastolic left ventricular cavity and the axis intersecting this and the right side of the posterior interventricular septum as the reference point and line. Segmental hemiaxis, area, wall thickness and those changes during cardiac cycle were measured and calculated in each octants. Regional contractility of the left ventricle was evaluated by systolic percent change of segmental hemiaxis, area and wall thickness. These parameters were significantly reduced in the infarcted segments documented by left ventriculography and electrocardiography. The area method is better than the hemiaxis system in both reproducibility and variability. The center of gravity of the left ventricular cavity determined by the computer shifted slightly towards the anterior wall during systole in normal subjects, possibly reflecting anterior swinging motion of the entire heart. The center of the gravity of the left ventricular cavity in myocardial infarction showed the tendency to shift towards the infarcted region, suggesting the possibility that the location of asynergic area can be detected by determining the direction of the gravity center shift during systole in patients with a single infarction. This finding gives a basis of using the fixed reference system for the detection of asynergy. The use of computers for the analysis of short-axis two-dimensional echocardiographic images is very useful for the quantification of regional contractility of the left ventricle in a clinical setting.