In vivo and ex vivo functional characterization of left ventricular remodelling after myocardial infarction in mice

AIMS: The interest in cardiac remodelling (REM) has steadily increased during recent years. The aim of this study was to functionally characterize REM following myocardial infarction (MI) in mice using high‐end in vivo and ex vivo methods. METHODS AND RESULTS: Myocardial infarction or sham operation was induced in A/J mice. Six weeks later, mice underwent cardiac magnetic resonance imaging and were subsequently sacrificed for ex vivo measurements on the isolated heart. Thereafter, hearts were trichrome stained for infarction size calculation. Magnetic resonance imaging showed significantly reduced ejection fraction (P < 0.01) as well as increased end‐systolic and end‐diastolic volumes (P < 0.01) after MI. The mean infarct size was 48.8 ± 6.9% of left ventricle. In the isolated working heart coronary flow (time point 20′: 6.6 ± 0.9 vs. 13.9 ± 1.6 mL/min, P < 0.01), cardiac output (time point 20′: 17.5 ± 2.6 vs. 36.1 ± 4.3 mL/min, P < 0.01) and pump function (80 mmHg: 2.15 ± 0.88 vs. 4.83 ± 0.76, P < 0.05) were significantly attenuated in MI hearts during all measurements. Systolic and diastolic wall stress were significantly elevated in MI animals. CONCLUSION: This two‐step approach is reasonable, since data quality increases while animals are not exposed to major additional interventions. Both the working heart and magnetic resonance imaging offer a reliable characterization of the functional changes that go along with the development of post‐MI REM. By combining these two techniques, additional information such as wall stress can be evaluated.