SERIAL ECHOCARDIOGRAPHIC ASSESSMENT OF LEFT VENTRICULAR DIMENSION AND FUNCTION IN MOUSE WITH MYOCARDIAL INFARCTION

X.M. Gao, A. Dart, E. Dewar, X-J Du.

Baker Medical Research Institute and Alfred Heart Centre, Melbourne, Victoria.

Numerous gene targeted mouse models provide powerful tools for study on the mechanism of heart failure (HF). This calls for establishing and characterising murine HF models.  We studied the time course of the left ventricle (LV) remodelling and function following myocardial infarction (MI) in C57 mice.  Mice underwent open-chest surgery to ligate the left coronary artery or sham-operation (SH).  Echocardiography was performed, using a HP5500 echo machine with 12MHz transducer, before and 1, 2.5, 6 and 9 weeks after surgery.  From 2-D guided M-mode traces, we measured LV diastolic and systolic dimension (LVDd, LVDs) and fractional shortening (FS%).  Finally, haemodynamics was determined by LV catheterisation and hearts examined morphologically.  Post-infarct death, due to HF or LV rupture, was 46%.  LVD and FS remained stable in SH mice (n = 10) during the study period.  In MI mice (n = 12), no changes in LVD and FS were observed at week 1.  During 2.5~9 week period, progressive increase in LVDd and LVDs, and decline in FS occurred vs SH (Table).  MI mice had lower LVSP (77±4 vs 95±3 mmHg), dP/dt_max (3455±209 vs 4889±339 mmHg/s), dP/dt_min (-2236±219 vs -4067±310 mmHg/s, all P<0.01), and suppressed inotropic response to i.v. dobutamine.  LVSP and dP/dt correlated well with echo parameters (r = 0.58~0.75).

Conclusion:  Echocardiography provides a reliable means for serial assessment of cardiac function in mice with MI.  LV remodelling and dysfunction in mice with MI are time-dependent processes.  Our findings provide baseline description on this murine model.

Serial changes in LVDd and FS.  *P<0.01 vs SH

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