The Effect of Decreases in Left Ventricle Volume and Area During Ventricular Fibrillation on Resuscitation Outcomes

ABSTRACT

PURPOSE: Dynamic changes in the dimensions of the left ventricle (LV) during cardiac arrest might influence the efficacy of CPR. However, the relationship between change in LV dimensions during cardiac arrest and CPR hemodynamics and outcomes have not yet been addressed. In the present study, we investigated changes in left ventricular volume and area during prolonged, untreated ventricular fibrillation (VF); we related those change to coronary perfusion pressure (CPP) during CPR and resuscitation outcomes. METHODS: In 12 domestic male pigs weighing 40+/-3 kg, VF was electrically induced and left untreated for 15 min. CPR was performed for 5 min prior to defibrillation. CPR was continued until the return of spontaneous circulation (ROSC) or for a maximum of 15 minutes. Mean aortic pressure and right atrial pressures were measured and CPP was calculated. LV dimensions were continuously assessed by echocardiographic measurement during the 15 minutes of interval VF. RESULTS: Six animals were successfully resuscitated. During the 15 minute interval of VF, LV area and volume were reduced in all animals. In animals that were not resuscitated, LV dimensions were significantly lower than those in resuscitated animals (p<0.01). These differences were observed after 10 minutes of VF. The animals with greater reduction in LV dimension during VF achieved significantly lower CPP during CPR in contrast to animals with larger LVs during VF. CONCLUSION: Greater decreases in LV volume and area during cardiac arrest are associated with low CPP during CPR and poor resuscitation outcomes. LV dimensions prior to starting CPR might therefore modulate the effectiveness of resuscitation interventions.