Ventricular remodeling in a mouse model of myocardial infarction

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Abstract
We investigated the suitability of studying ventricular remodeling in a mouse model of myocardial infarction (MI). We performed left coronary ligation (n = 22) or a sham procedure (n = 21) on normal C57BL/6J mice. Six weeks later, animals underwent echocardiography and hemodynamic evaluation. Left ventricular (LV) volume at a common distending pressure was calculated from passive pressure-volume curves. The MI group exhibited lower systolic blood pressure (P < 0.05), higher LV end-diastolic pressure (P < 0.05), and lower peak first derivative of LV pressure (dP/dt,P < 0.05) than the sham group. Mice with moderate (n = 11) and large (≥40%, n = 11) MIs displayed increased LV mass-to-body weight ratio (P < 0.02 andP < 0.01, respectively, vs. sham group), whereas only the large-MI group exhibited increased right ventricular mass-to-body weight ratio (P < 0.01). LV volumes were increased in the moderate-MI group (P= 0.059 vs. sham group) and to a much greater extent in the large-MI group (P < 0.0001 vs. sham group). The moderate- and large-MI groups also exhibited increases in LV end-diastolic diameter (P < 0.03 andP < 0.0001, respectively, vs. sham group) and LV end-systolic diameter (P< 0.01 and P < 0.0001, respectively, vs. sham group) with decreased fractional shortening (P < 0.01 for both). These data demonstrate ventricular remodeling in a mouse model of MI and confirm the feasibility of quantifying indexes of remodeling in vivo and postmortem. This model will be of particular usefulness when applied to transgenic strains.