Assessment of left ventricular systolic function using contrast two-dimensional echocardiography with a high-frequency transducer in the awake murine model of myocardial infarction

The estimation of global left ventricular function using M-mode echocardiography has technical limitations in the murine model of myocardial infarction (MI), but the recent improvements in 2-dimensional (2-D) echocardiography using a high-frequency transducer provide more accessible images. Furthermore, intravenous injection of contrast agent has the additional benefit of enhancing the endocardial border in the murine heart. The present study was designed to evaluate the value of 2-D echocardiography with intravenous injection of contrast agent in the assessment of global systolic function of the murine heart with MI. Two-dimensional and M-mode echocardiography without and with intravenous injection of contrast agent (Optison, 0.1-0.15 ml) were performed in 76 awake mice 2 days before and 2 days after left coronary artery ligation. Fractional shortening (FS) was calculated from the end-diastolic and end-systolic diameters on M-mode echocardiography, and fractional area change (FAC) from the end-diastolic and end-systolic areas on 2-D echocardiography. Both FS and FAC were compared with the areas of hypoperfusion observed in the pathological samples. The use of contrast agent improved the number of hearts that could be evaluated by both the M-mode and 2-D method (M-mode: non-contrast 87% vs contrast 99%, p<0.01; 2-D: non-contrast 26% vs contrast 89%, p<0.001). FAC from the 2-D method correlated better with the region of hypoperfusion in the pathological samples than did FS from the M-mode method (FAC: r=0.84 vs FS: r=0.51). In conclusion, FAC obtained from 2-D contrast echocardiography is useful for noninvasive assessment of global systolic function in infarcted murine hearts and can be used to serially assess systolic function in various models of the murine heart.