Abstract 524: Stretching Motion Characterized by Circumferential Strain by Speckle Tracking is a Specific Marker of Myocardial Ischemia
Purpose: Early systolic stretching myocardial motion and post systolic shortening has been reported as early markers of myocardial ischemia. Along with these findings, post systolic shortening has been investigated as a potential marker of viability and myocardial dysfunction, while few data had addressed stretching motion for identifying myocardial ischemia. The present experimental study reported the features of stretching motion during induced ischemia.
Methods: The study was conducted in 15 anesthetized pigs who underwent acute myocardial ischemia induced by balloon coronary occlusion (left coronary descending artery, n =6). Stretching motion was quantified using circumferential strain by speckle tracking computed from short axis view (closed chest) before and during myocardial early (5–15′) and late (60′) ischemia. Stretching motion was defined as positive strain during the systolic period and the stretching index was expressed the ratio of stretching magnitude over peak systolic circumferential strain.
Results: At baseline, stretching motion was observed in normal contractile segment with a relatively low stretching index (0.18 ±0.19). During coronary artery occlusion, stretching index remained low in remote segment (see Figure⇓ early and late ischemia. In contrast, in ischemic segments stretching index dramatically increased during the coronary occlusion. Importantly, stretching index >0.4 used to defined a stretching motion, specifically identified (89.6%) early and late ischemic segments.
Conclusions: Stretching motion characterized by circumferential strain by speckle tracking appears as a specific marker to identify ischemic segments.