Evaluation of left ventricular myocardial regional function in normal and myocardial infarction of mongrel dogs with displacement curve

Objective To study the features of normal and infracted left ventricular regional wall motion of mongrel dogs with displacement curve, to investigate its suitable and quantitative standards of evaluating myocardial function in physiological and pathophysiological conditions. Methods Twenty-seven of the left anterior descending coronary arteries of mongrel dogs were ligated with opened chest surgery under systemic anesthesia. Activity Doppler tissue images of three cardiac cycles were obtained on apical views (2-chamber, 4-chamber, 5-chamber) before and after myocardial infarction. EchoPAC PC off-line digital ultrasound workstation was used to analyze the displacement curve at different myocardial segments of the left ventricle. All of displacement curve peaks on long axis and the time to peak were recorded. The time of starting isovolumic relaxation, and the duration of isovolumic contraction and relaxation were calculated. Results Displacement curve showed regularity in normal subjects. In myocardial infarction, peaks of all segments of anterior septum, anterior wall, apex and posterior septum were significantly lower than that in healthy subjects (P≤0.001). The duration of isovolumic relaxation was prolonged than that in healthy subjects (P0.05). Conclusion Regional wall motion abnormalities in myocardial infarction were able to be evaluated with displacement curve. The descended peak of displacement and/ or the prolonged duration of isovolumic diastole may be the early sensitive indicators of regional wall motion abnormalities in myocardial infarction.