Myocardial Dysfunction Contributes to Irreversible Hemorrhagic Shock

We have performed a study of the effects of different time periods of hemorrhagic shock on isolated heart function of guinea pigs. In vivo hemodynamics were monitored during hemorrhage, shock and resuscitation and then intrinsic function of the heart was assessed. Three time periods were studied - 1, 2 or 3 hours of shock. In some animals shock lasted for 1 hour and then guinea pigs were resuscitated with whole blood or dextran 70,000 MW (same volume as the blood that was removed). The data collected from the isolated heart indicated that hemorrhagic shock lasting I, 2 or 3 hours by itself did not cause major dysfunction or the heart. The only change in heart function that seemed to occur was in the 3 hour shock group in which the left ventricular compliance was slightly depressed. In annals that had been resuscitated with whole blood or with 6% dextran, ventricular performance was depressed compared to control hearts and compared to hearts from animals in hemorrhagic shock suggesting that reperfusion contributed significantly to myocardial dysfunction resulting from hemorrhagic shock.