QUANTIFICATION OF CARDIAC DYSSYNCHRONY IN MICE AFTER MYOCARDIAL INFARCTION USING HIGH RESOLUTION ULTRASOUND
Contractile dyssynchrony in the left ventricles (LVs) of murine hearts post myocardial infarction (MI) was assessed using high resolution 30 MHz ultrasound. Long axis and mid-ventricular short axis image sequences were obtained from six post-Mi C57B1/6 mice. Two normal C57B1/6 mice were also scanned as non-infarcted controls. The ultrasound images had an axial resolution of approximately 50 mum, a lateral resolution of approximately 100 mum, and a temporal resolution of 1000 frames/s (achieved via retrospective compilation of LCG-gated acquisitions). Myocardial tissue displacement was measured using a 2D image tracking algorithm with sub-pixel resolution. Regional myocardial displacement analyses revealed prolonged regional systole and delay to peak displacement, as well as reduced displacement, in regions adjacent to infarcted zones. The regional delays in time to peak displacement ranged from 12 to 20 ms in mouse hearts with large MI. Thus, high resolution 2D ultrasound imaging followed by 2D image tracking analysis provides an efficient and cost-effective method for characterizing LV dyssynchrony in murine hearts post-MI