Assessment of left ventricle myocardial deformation in a hemorrhagic shock swine model by two-dimensional speckle tracking echocardiography

BACKGROUND Trauma-induced secondary cardiac injury has been associated with significant adverse cardiovascular events. Speckle tracking echocardiography is a novel technology that allows an accurate and reproducible cardiac structure and function assessment. We evaluated the left ventricle (LV) myocardial deformation by speckle tracking echocardiography in a hemorrhagic shock (HS) swine model. METHODS Seven healthy male Landrace pigs were included in this study. Severe HS was reached through three sequentially blood withdraws of 20% of estimated blood volume, and it was maintained for 60 minutes. Volume resuscitation was performed using all precollected blood volume. A 1.8- to 4.2-MHz phased-array transducer was used to acquire the two-dimensional echocardiography images. Strain measurements were obtained semiautomatically by wall motion tracking software. Results are presented as medians and interquartile ranges and compared using Wilcoxon rank-sum test. A p value of <0.05 was considered statistically significant. RESULTS The median weight was 32 (26.1-33) kg, and the median total blood volume withdrawn was 1,100 (1,080-1,190) mL. During the severe HS period, the median arterial systemic pressure was 39 (36-46) mm Hg, and the cardiac index was 1.7 (1.6-2.0) L/min/m2. There was statistically significant absolute decrease in the global longitudinal strain 2 hours postresuscitation comparing with the basal measurements (-9.6% [-10.7 to -8.0%] vs. -7.9% [-8.1 to -7.4%], p = 0.03). There were no statistically significant differences between the basal and 2 hours postresuscitation assessments in the invasive/noninvasive hemodynamic, other two-dimensional echocardiogram (LV ejection fraction, 49.2% [44-54.3%] vs. 53.2% [51.5-55%]; p = 0.09), and circumferential strain (-10.6% [-14.4 to -9.0%] vs. -8.5% [-8.6 to -5.2%], p = 0.06) parameters. CONCLUSION In this experimental swine model of controlled HS, LV global longitudinal strain analysis accurately characterizes the timing and magnitude of subclinical cardiac dysfunction associated with trauma-induced secondary cardiac injury.