Tissue Doppler imaging differentiates transmural from nontransmural acute myocardial infarction after reperfusion therapy

Background-The evaluation of transmural extent of necrosis after acute myoc ardial infarction remains a major problem in clinical practice. We sought t o determine whether color M-mode tissue Doppler imaging (TDI) could differe ntiate transmural from nontransmural myocardial infarction. Methods and Results-Twenty-one anesthetized open-chest dogs underwent 90 or 120 minutes of left anterior descending coronary artery occlusion followed by 180 minutes of reperfusion, The transmural extension of infarct was mea sured by triphenyltetrazolium chloride (TTC) staining. Segment shortening i n the endocardium and epicardium of the anterior and posterior walls was as sessed by sonomicrometry. Regional myocardial blood flow was measured by ra dioactive microspheres. TDT was obtained from an epicardial short-axis view . We calculated systolic and diastolic velocities within the endocardium an d epicardium of myocardial walls and the subsequent myocardial velocity gra dient (MVG). TTC staining could identify 2 groups according to the transmur al extent of necrosis: 15 dogs had a nontransmural (NT) necrosis (42+/-3% o f wall thickness), and 6 dogs developed a transmural (T) infarct (81+/-4% o f wall thickness). In both groups, ischemia resulted in a significant and s imilar reduction in endocardial and epicardial velocities, with a resulting low systolic MVG in the anterior wall (0.10+/-0.07 in NT and 0.10+/-0.08 s (-1) in T). At 60 minutes of reperfusion, systolic MVG failed to change sig nificantly in the transmural group (-0.20+/-0.09 s(-1)). In contrast, it in creased significantly after reflow in the NT group compared with ischemic v alues (-0.99+/-0.20 versus 0.10+/-0.07 s(-1), P<0.05). Conclusions-TDI can differentiate transmural from nontransmural myocardial infarction early after reperfusion.