19

Abstract

Introduction: Post-resuscitation myocardial dysfunction is one of leading causes of death after resuscitation from cardiac arrest. It is generally considered as a reversible myocardial stunning. However, its mechanism and especially whether there is myocardial tissue damage after global ischemia of cardiac arrest remain unclear. In the present study, we investigated the relationship between the severity of post-resuscitation myocardial dysfunction and myocardial injury biomarkers. Methods: Thirty-six male Sprague-Dawley rats weighing between 450-550g were randomized into 6 groups: 1) placebo; 2) epinephrine; 3) epinephrine with α1- blocker; 4) epinephrine with α2- blocker; 5) epinephrine with β- blocker and; 6) epinephrine with β- and α1- blocker. Ventricular fibrillation (VF) was electrically induced. CPR was initiated after 8 mins of untreated VF and continued for 8 mins. Defibrillation was then attempted. Ejection fraction (EF) and myocardial performance index (MPI) were measured by echocardiography at baseline and hourly interval for 4 hrs after resuscitation. The serum concentrations of Troponin I (Tn I) and N-terminal pro-brain natriuretic peptide (NT-pro BNP) were measured at baseline, 1 and 4 hrs after resuscitation by the ELISA kits. Results: All animals except for one in the placebo group were resuscitated. The post-resuscitation myocardial function measured by EF and MPI were significantly impaired after resuscitation in all animals. The most severe impairment was observed in epinephrine with α2- blocker and epinephrine treated animals. The impairment of myocardial mechanical function was parallel with myocardial injury biomarkers measured by Tn I and NT-pro BNP (EF and Tn I: r = -0.639, p < 0.01, EF and NT-pro BNP: r = -0.729, p < 0.01 and MPI and Tn I: r =-0.604, p < 0.01, MPI and NT-pro BNP: r = -0.649, p < 0.01, respectively). Conclusions: The severity of post-resuscitation myocardial dysfunction was closely related to myocardial injury biomarkers which indicate that post-resuscitation myocardial dysfunction is associated with myocardial tissue injury.