Myocardial performance after contusion with concurrent hypovolemia

Myocardial contusion may present as a benign nonclinical event or a life-threatening emergency. Although cardiac output is recognized to be decreased with major contusion, the contribution of hypovolemic shock to myocardial dysfunction is unclear. This study was designed to evaluate the relationship between myocardial contusion and hypovolemic shock. After Sprague-Dawley rats were anesthetized, contusions were administered at either 80 psi or 120 psi. Half of each group then underwent hypovolemic shock. After 24 hours of recovery, cardiac hemodynamics were studied in each subgroup using the Neely-Langendorff apparatus. Isoenzymes and histology were evaluated as well. The data showed that rats undergoing hypovolemic shock in each subgroup had a significant decrease in cardiac output when compared with their controls. This decrease was more pronounced in the 120-psi group. Cardiac isoenzyme levels were elevated in all groups. Microscopic evaluations showed contusion in the controls and necrosis in the shock groups. Patients whose injuries are compatible with myocardial contusion and hypovolemic shock should be resuscitated quickly and evaluated for myocardial dysfunction secondary to infarction.