Quantitative tissue velocity imaging for the evaluation of regional diastolic function of left ventricle in dogs with acute myocardial infarction

Objective To evaluate the characteristics of the regional wall longitudinal motion of the left ventricle during isovolumic relaxation phase and rapid filling phase in dogs with acute myocardial infarc- tion,and to analyze their significance.Methods We studied 24 dogs in healthy and after acute myocardial infarction with quantitative tissue velocity imaging(QTVI).The apical four chamber,five chamber and two chamber views were used and sample volumes were within endocardium.Myocardial velocity profiles were taken at the basal,mid and apical segments,including anterior,inferior,lateral and posterior walls of the left ventricle,and posterior and anterior septum.Segmental velocity patterns during normal status were com- pared with abnormal segments in the dogs during ischemia.Peak myocardial velocity and time of LV seg- ments during early diastole time(Ve)and isovolumic relaxation time(Vivrpl,Vivrp2)as well as corre- sponding time(T1,T2)were measured.The mean acceleration(a)was calculated during isovolumic relax- ation.Results The Ve and Vivrpl were significantly reduced in the abnormal segments in the dogs during ischemia(P＜0.05);whereas the Vivrp2 had no significant(P＞0.05).But the acceleration increased in the infarct anterior wall and anterior septum of the apical segment(P＜0.05 or P＜0.01),and decreased in the lateral wall,posterior septum and inferior wall,posterior wall(P＜0.01).The acceleration also in- creased in the infarct anterior wall and anterior septum of the medial segment(P＞0.05)and decreased in the posterior septum(P＜0.01).And in the posterior septum,anterior septum and anterior wall of the basal segment,the acceleration decreased(P＜0.05 or P＜0.01).Conclusions QTVI is useful in evaluating regional myocardial diastolic function of the left ventricle,and it may play an important role in the detection of early myocardial ischemia.