Regional myocardium function in rabbit with acute myocardial ischemia assessed by velocity vector imaging

Objective To utilize velocity vector imaging (VVI) in analyzing regional myocardium function within 30 minutes before and after myocardial ischemia induced by occlusion of coronary artery in New Zealand white rabbits and to evaluate the changes of longitudinal and brachydiagonal segmental left ventricular(LV) systolic function in rabbits with acute myocardial ischemia. Methods Thirty New Zealand white rabbits were divided into groups of myocardial ischemia and sham operation. All rabbits were performed by echocardiography before the operation and after the operation within 30 minutes and dynamic cardiac images were collected. All of these images were analyzed off-line using VVI software. These LV myocardium longitudinal and brachydiagonal VVI parameters:systolic velocity(Vs),systolic strain(Ss) and systolic strain rate (SRs) were assessed and analyzed. Results Compared with those before operation and sham operation group in ischemia condition,the longitudinal Vs were lower in the apical segments of anteroseptum and posterior wall (P0.05); the longitudinal Ss,SRs were lower in the middle and apical segments of anteroseptum wall,the apical segment of posterior wall (P0.05); the radial Vs were lower in the basal segments of anterior and lateral wall,the middle segments of anteroseptum,anterior and lateral wall,all apical segments(P0.05); the circumferential Ss and SRs were lower in the basal segments of anteroseptum,anterior and lateral wall,the middle segment of anteroseptum,anterior,lateral and posterior wall and all apical segments(P0.05). Conclusions The regional LV myocardial systolic function decrease after acute myocardial ischemia in longitudinal and brachydiagonal directions. The VVI is a novel noninvasive tool to quantitatively and objectively assess LV regional myocardial systolic function,which could provide another useful method for early diagnosis of acute myocardial ischemia.