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

Abstract

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 RESULTS:The median weight was 32 (26.1-33) kg, and the median total blood volume withdrawn was 1,100 (1,080-1,190) mL.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/m 2 . 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 (LVejection 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.