Abstract
BackgroundSepsis-induced myocardial dysfunction is a common and severe complication of septic shock. However, conventional echocardiography often fails to reveal myocardial depression in severe sepsis. Recently, strain measurements based on speckle tracking echocardiography (STE) have been used to evaluate cardiac function.AimsTo investigate the role of STE in detecting lipopolysaccharide (LPS)-induced cardiac dysfunction, M-mode and 2-D echocardiography were used in LPS-treated mice.MethodsThe mice were treated with a 10mg/kg (n = 10), 20mg/kg (n = 10) or 25mg/kg LPS (n = 30) to induce cardiac dysfunction. Subsequently, the ejection fraction (EF) and fractional shortening (FS) were measured with standard M-mode tracings, whereas the circumferential (Scirc) and radial strain (Srad) were measured with STE. Serum biochemical and cardiac histopathological examinations were performed to assess sepsis-induced myocardial injury.Results20mg/kg LPS resulted in more deterioration, myocardial damage and cardiac contractile dysfunction based on serum biochemical and histological examinations. The mice that were subjected to 20mg/kg LPS exhibited reduced Scirc but no reduction in Srad, whereas on conventional echocardiography, the ejection fraction (EF) and fractional shortening (FS) were similar in the 10mg/kg and 20mg/kg groups. Moreover, Scirc was positively correlated with body temperature in the mice at 20 h after LPS injection (r = 0.746, p = 0.001), but no significant correlation was observed between Srad and body temperature (r = 0.356, p = 0.123). Moreover, the mice with high Scirc (-5.9% to -10.4%) exhibited reduced mortality following the administration of 25mg/kg LPS (p = 0.03) compared with the low-strain group (-2% to -5.9%).ConclusionsTaken together, our findings indicate that circumferential strain is a specific and reliable indicator for evaluating LPS-induced cardiac dysfunction in mice.
Highlights
Sepsis is responsible for millions of deaths worldwide each year and is a frequent cause of death among people who have been hospitalized
Our findings indicate that circumferential strain is a specific and reliable indicator for evaluating LPS-induced cardiac dysfunction in mice
Conventional echocardiography revealed no difference in global cardiac function between the 10mg/kg and 20mg/kg groups (Fig 1)
Summary
Sepsis is responsible for millions of deaths worldwide each year and is a frequent cause of death among people who have been hospitalized. Septic cardiomyopathy is a well-described complication of severe sepsis and septic shock[1]. Increasing evidence suggests that enhanced production of a large number of inflammatory cytokines can directly or indirectly cause cardiac dysfunction, the precise mechanisms for myocardial dysfunction in sepsis remain undefined[1,3,4]. There are controversies regarding the pathophysiology of sepsis-induced myocardial depression and its treatment strategies, many of which are still in the experimental phase. The administration of lipopolysaccharide (LPS) to laboratory animals, especially mice, has been widely used to study the mechanisms of septic cardiomyopathy[5]. Sepsis-induced myocardial dysfunction is a common and severe complication of septic shock. Conventional echocardiography often fails to reveal myocardial depression in severe sepsis. Strain measurements based on speckle tracking echocardiography (STE) have been used to evaluate cardiac function
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