RESUMEN
Acute changes in mechanical performance [spontaneous rate and contractile force of the hearts] were followed after blunt cardiac trauma, ethanol infusion, and ethanol infusion with blunt cardiac trauma in 40 anesthetized male rabbits. Impact was delivered to the whole anterior pericardium by a single blow with a weighted pendulum. Energy delivered, which was calculated as kinetic energy, was 67 +/- 7 m Joules/g. Impact alone caused complete cardiac arrest, followed by sequential ventricular recovery, atrial recovery with atrioventricular [A-V] block, transient normal sinus rhythm, tachycardia and normal sinus rhythm. These transient cardiac dysfunctions were accompanied with significant reductions in the spontaneous rate and contractile force, except the height of auricular contraction during A-V block which showed a significant rise. All animals survived impact and regained nearly normal mechanical performance within 10 minutes after impact. Intravenous infusion of ethanol [average blood alcohol concentration, 65 +/- 1 mg%], resulted in nonsignificant decrease in the mechanical performance, but, when combined with trauma, caused a mortality rate of 75%. All animals died from complete and persistent cardiac arrest after marked slowdown in the spontaneous rate and severe weakness in the contractile force. It is concluded that even low blood alcohol concentrations can significantly reduce cardiac performance in the presence of otherwise nonfatal cardiac injury