A comparison of myocardial function after primary cardiac and primary asphyxial cardiac arrest

Although myocardial dysfunction after resuscitation from ventricular fibril lation (VF) has been extensively investigated, less is known of the functio n of the myocardium after asphyxial cardiac arrest. The present experimenta l study was designed to compare postresuscitation left ventricular (LV) fun ction after cardiac arrest caused by asphyxia with that of cardiac arrest i nduced by dysrhythmia. Four groups of Sprague-Dawley rats, which included e ight animals in each group, were investigated. In the first two groups, car diac arrest followed asphyxia produced by neuromuscular blockade with and w ithout airway obstruction. In a third group, cardiac arrest was induced by electrical fibrillation of the ventricle. The fourth group represented anim als in which the duration of asphyxial cardiac arrest was maintained for a time interval corresponding to that of the VF group. The fourth group recei ved approximately the same number of electrical shocks as the third (VF) gr oup. All animals were successfully resuscitated with precordial compression and mechanical ventilation. Postresuscitation measurements, including card iac output, LV end-diastolic pressure (LVEDP), rate of pressure rise at LV pressure of 40 mm Hg (LV dP/dt(40)), and negative LV dP/dt, demonstrated de creased myocardial function in each group. No differences in cardiac functi on were observed between the animals with primary respiratory arrest whethe r or not the airway was obstructed. However, disproportionate and consisten tly greater impairment in myocardial function followed primary cardiac arre st due to VF when compared with equal duration of asphyxial cardiac arrest. We conclude that in this healthy animal model, asphyxial cardiac arrest re sulted in significantly lesser impairment of postresuscitation myocardial f unction when compared with cardiac arrest caused by VF.