Modeling Cardiac Dysfunction Following Traumatic Hemorrhage Injury: Impact on Myocardial Integrity

Abstract

Cardiac dysfunction (CD) importantly contributes to mortality in trauma patients, who survive their initial injuries following successful hemostatic resuscitation. This poor outcome has been correlated with elevated biomarkers of myocardial injury, but the pathophysiology triggering this CD remains unknown. We investigated the pathophysiology of acute CD after trauma using a mouse model of trauma hemorrhage shock (THS)-induced CD with echocardiographic guidance of fluid resuscitation, to assess the THS impact on myocardial integrity and function. Mice were subjected to trauma (soft tissue and bone fracture) and different degrees of hemorrhage severity (pressure controlled ~MABP < 35 mmHg or <65 mmHg) for 1 h, to characterize the acute impact on cardiac function. In a second study, mice were subjected to trauma and hemorrhage (MABP < 35 mmHg) for 1 h, then underwent two echocardiographic-guided resuscitations to baseline stroke volume at 60 and 120 min, and were monitored up to 180 min to study the longer impact of THS following resuscitation. Naïve and sham animals were used as controls. At 60 min post-THS injury, animals showed a lower cardiac output (CO) and stroke volume (SV) and an early rise of heart fatty acid-binding protein (H-FABP = 167 ± 38 ng/ml; 90% increase from shams, 3.54 ± 3.06 ng/ml), when subjected to severe hemorrhage and injury. Despite resuscitation, these animals maintained lower CO (6 ml/min vs. 23 ml/min), lower SV (10 μl vs. 46 μl; both ~75% decreased), and higher H-FABP (levels (340 ± 115 ng/ml vs. 10.3 ± 0.2 ng/ml; all THS vs. shams, P < 0.001) at 180 min post-THS injury. Histopathological and flow-cytometry analysis of the heart confirmed an influx of circulatory leukocytes, compared to non-injured hearts. Myocardial injury was supported by an increase of troponin I and h-FABP and the widespread ultrastructural disorganization of the morphology of sarcomeres and mitochondria. DNA fragmentation and chromatin condensation driven by leakage of apoptosis-inducing factor (AIF) may suggest a mitochondria-driven progressive cell death. THS modeling in the mouse results in cardiomyocyte damage and reduced myocardial function, which mimics the cardiac dysfunction seen in trauma patients. This CD model may, therefore, provide further understanding to the mechanisms underlying CD and act as a tool for developing cardioprotective therapeutics to improve survival after injury.

Exploratory Investigation of the Plasma Proteome Associated with the Endotheliopathy of Trauma

“…Histologic changes in cardiomyocytes identified in trauma patients upon autopsy include congestion, interstitial edema, and myofibril degeneration [ 175 , 176 ]. Similar sarcomere disorganization has been observed in murine models of hemorrhagic shock [ 177 ].…”

Effects of Trauma-Related Shock on Myocardial Function in the Early Period Using Transthoracic Echocardiography

“…several animal experimental studies, traumatic hemorrhagic shock has been proven to cause cardiac injury and dysfunction as an indirect consequence of trauma and hemorrhage [6,21,22]. There are several studies about the impact of DAMPs on myocardial function in non-traumatic cases.…”

Sex as Biological Variable in Cardiac Mitochondrial Bioenergetic Responses to Acute Stress

“…Cardiac damage and dysfunction following trauma, sepsis, and heart surgery (having myocardial ischemia) largely impact clinical outcomes [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. Over 50% of all critically injured trauma patients requiring intensive care unit (ICU) treatment develop cardiovascular dysfunction, which contributes to 20% mortality [ 5 , 8 ]. Septic patients with cardiovascular dysfunction are three to four times more likely to die than those without cardiac damage [ 6 , 7 ].…”

“…TNFα and ROS significantly increase preceding cardiac damage and dysfunction following trauma, sepsis, and myocardial ischemia [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. Local cardiac inflammatory response and oxidative stress have been demonstrated as the primary driving force for cardiomyocyte impairment and functional damage following these injuries [ 8 , 19 , 21 , 22 , 23 , 24 , 25 , 26 ]. On the other hand, sex dimorphism impacts consequences after trauma, sepsis, or myocardial ischemia [ 27 , 28 , 29 , 30 , 31 , 32 ].…”