Experiment Of Assessing Dog Acute Ischemic Myocardium Area By Strain Rate Imaging

Objective To assess ischemic myocardium area by strain rate imaging (SRI).Methods 11 dogs were subjected to LAD coronary artery occlusion for acute ischemia. M-mode of strain-rate defined the cut-off value of ischemic myocardium, and marked in anterior and inferior in 2D images, respectively. Ischemic area was curved and compared with pathologic result. SR was compared with non-ischemic, the cut-off value and adjacent ischemic segments. Results Linear correlation existed between pathology and strain rate ischemic area (r=0.884, P<0.001). The SR parameters were lower in ischemic and the cut-off than in non-ischemic segments. Peak SR of systole (S_sr), early diastole (E_sr), and late diastole (A_Sr) in cut-off segments lowered (P<0.05). Time to onset of regional relaxation (T_r) was prolonged (P=0.012). IVR_sr/S_sr significantly increased in cut-off and ischemia segments. Among SR parameters, IVR_sr/S_sr and Tr had 88%, 83% sensitivity, and 93%, 80% specificity respectively to detect acute ischemia. Conclusion Strain rate imaging can accurately assess ischemic myocardium area, IVR_sr/S_sr and T_r are the most sensitive parameters identifying ischemic myocardium among SR parameters.