Serial Echocardiographic Assessment of Left Ventricular Dimensions and Function After Myocardial Infarction in Mice

Objective: To test the usage of serial echocardiography in mice with induced myocardial infarct (MI) and to characterize the mouse model of MI.

Methods: C57 mice underwent open-chest surgery to induce left coronary artery occlusion or sham-operation (SH). Echocardiography was performed before and at 1, 2.5, 6 and 9 weeks after surgery. Left ventricular end diastolic and end systolic dimensions (LVEDd, LVESd) and fractional shortening (FS) were measured. Haemodynamics was determined at week 9 by LV catheterization and hearts were examined morphologically.

Results: Post-infarct mortality was 46% (10/22), of which, 70% died of acute heart failure or LV rupture within the first week. LV dimensions and FS remained stable in SH group (n = 10) during the study period. In surviving MI mice (n = 12), there was modest LV dilatation and fall in FS at week 1. Compared with week 0 values, there were progressive increase in LVEDd (+50(-)+66%) and LVESd (+124(-)+171%), and decline in FS (-53(-)-73%) during the 2.5-9 week period. Infarcted mice also had lower LV systolic pressure (LVSP), dP/dtmax and dP/dtmin (all P < 0.01 vs. SH group). Infarct size, LVSP and dP/dt significantly correlated with FS and LV dimensions (r = 0.61-0.80, all P < 0.01).

Conclusions: LV remodeling and dysfunction in mice with MI are time-dependent processes and early remodeling seems associated with high risk of rupture and acute pump failure. Our findings provide a baseline description of this murine model and confirm echocardiography as a reliable means to serially assess changes of cardiac structure and function after MI.