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The role of speckle tracking echocardiography in assessment of lipopolysaccharide-induced myocardial dysfunction in mice.

BACKGROUND
Sepsis-induced myocardial dysfunction is a common and severe complication of septic shock. Conventional echocardiography often fails to reveal myocardial depression in severe sepsis due to hemodynamic changes; in contrast, decline of strain measurements by speckle tracking echocardiography (STE) may indicate impaired cardiac function. This study investigates the role of STE in detecting lipopolysaccharide (LPS)-induced cardiac dysfunction with mouse models.


METHODS
We evaluated cardiac function in 20 mice at baseline, 6 h (n=10) and 20 h (n=10) after LPS injection to monitor the development of heart failure induced by severe sepsis using 2-D and M-mode echocardiography. Ejection fraction (EF) and fractional shortening (FS) were measured with standard M-mode tracings, whereas circumferential and radial strain was derived from STE. Serum biochemical and cardiac histopathological examinations were performed to determine sepsis-induced myocardial injury.


RESULTS
Left ventricular (LV) myocardial function was significantly reduced at 6 h after LPS treatment assessed by circumferential strain (-14.65%±3.00% to -8.48%±1.72%, P=0.006), whereas there were no significant differences between 6 and 20 h group. Conversely, EF and FS were significantly increased at 20 h when comparing to 6 h (P<0.05) accompanied with marked decreases in EF and FS 6 h following LPS administration. Consistent with strain echocardiographic results, we showed that LPS injection leaded to elevated serum level of cardiac Troponin-T (cTnT), CK-MB and rising leucocytes infiltration into myocardium within 20 h.


CONCLUSIONS
Altogether, these results demonstrate that, circumferential strain by STE is a specific and reliable value for evaluating LPS-induced cardiac dysfunction in mice.