11B-2 Temporal and Spatial Analysis of Cardiac Contractile Dyssynchrony in Mouse Left Ventricle Post Myocardial Infarction Using High Resolution Ultrasound

Left ventricular (LV) contractile dyssynchrony in murine hearts late (>=28 days) after reperfused myocardial infarction (post-MI) was assessed using high frequency 30 MHz B-Mode ultrasound imaging. Nine post-MI C57BL/6 mice were analyzed in both the short- and long-axis views for cardiac dyssynchrony, and six normal mice were examined for controls. Regional time to peak displacement (T_{peak_d}) and time to peak strain (T_{peak_s}) were calculated in 36 sectors along the myocardial circumference. The standard deviations (SD_T_{peak_d} and SD_T_{peak_s}) were computed among non-infarcted myocardial regions for each mouse, and were compared between the normal and post-MI mouse groups with student´s t test. The comparison revealed that SD_Tpeakd and SD_Tpeaks were significantly larger in the post-MI hearts than in the normal hearts. The displacement uniformity ratio was determined to be 0.97 plusmn 0.01 and 0.85 plusmn 0.07 for radial and circumferential displacements in the normal hearts, respectively, and 0.59 plusmn 0.17 and 0.64 plusmn 0.24 in the post- Mi hearts.