Myocardial performance index following electrically induced or ischemically induced cardiac arrest

We sought to investigate the echocardiographic myocardial performance index (MPI) to assess post-resuscitation myocardial function following electrically and ischemically induced ventricular fibrillation (VF).

VF was induced in fourteen anesthetized pigs weighing 38+/-4 kg. VF was induced electrically in seven animals and ischemically, following transient occlusion of the left anterior descending coronary artery (LAD), in the remaining seven animals. VF was untreated for 7 min after which CPR, including precordial compression and mechanical ventilation was begun. Defibrillation was attempted after 5 min of CPR. MPI, ejection fraction (EF) and fractional area change (FAC) were measured hourly during the following 4 h interval post-resuscitation.

Five of seven animals were resuscitated in the electrically induced VF group, and four of seven animals in the ischemically induced VF group. No difference in EF and FAC were observed between the two groups. The MPI, however, was significantly greater at 60 min and 120 min post-resuscitation in animals after ischemically induced VF (p<0.05).

In this model, left ventricular (LV) MPI was a more sensitive and useful quantitative parameter to assess the LV function than the EF and FAC measurements used routinely. MPI measurements indicated that post-resuscitation myocardial dysfunction may be more severe after ischemically induced VF compared to the electrically induced VF.