Myocardial strain map of remodeling

Objective: Long term sequelae of myocardial infarction remains a major cause of morbidity and mortality. We hypothesize that we can map infarct expansion and hypocontractility that occurs during remodeling with regional myocardial strain data. Methods: Using an ovine model (n =5), an MI was created by ligation of two LAD diagonal branches. Sixteen sonomicrometry transducers were placed into the left ventricle. Progression was monitored with sonomicrometry, hemodynamic, and echo at 2, 4 and 8 weeks post MI. Using sonomicrometry array localization (SAL), a 3D coordinate was constructed to calculate regional motion of the LV free wall over a cardiac cycle. An areal strain map was created by analysis of transducer displacement over time and normalized to respective baseline values and computed as a percentage. Results: The regional strain is expressed as a percent change from baseline ([S-Sb]/ Sb × 100). Therefore, the most positive areas of strain (red) indicate the most dyskinetic regions of the myocardium. The infarct zone corresponded to a strain area of 55–75, adjacent zone = 10–20, and remote zone = -10 to 5. Infarct expansion was confirmed by echocardiogram. Conclusions: By using SAL we can construct a regional strain map of the LV that corresponds to the degree of infarct expansion and LV dilation.Figure