Abstract 92: Outcomes of CPR in a Rat Model of Chronic Myocardial Ischemia
Introduction: A majority of sudden cardiac deaths occur in victims who have ischemic heart disease. In such patients, lesser success of CPR and lower likely ultimate survival are assumed. In the present study, we investigated this issue in a model of chronic myocardial ischemia in Sprague-Dawley rats.
Methods: The LAD was partially constricted to 350 μm in open chest male breeder rats weighing 500±50g. Global cardiac performance prior to and 4 weeks after ligation was measured with a Sonos 2500 echocardiographic system utilizing a 7.5 Hz transducer (Model 21363A, Hewlett-Packard Co., Medical Products Group, Andover, MA). VF was electrically induced. After 6 min of untreated VF, mechanical ventilation and precordial compression were started and continued for 6 min. Defibrillation was attempted with a 2 J precordial biphasic shock. Identical procedures were followed in sham-operated animals.
Results: Significant decreases in ejection fraction (EF), increases in left ventricular end-diastolic volume (LVEDV), and increases in left ventricular end-systolic volume (LVESV) were documented in LAD constricted animals. Surprisingly, no differences in outcome with respect to return of spontaneous circulation (ROSC), nor duration of 72 hour survival were observed. Numerically but non-significantly greater numbers of shocks were required for defibrillation in animals with heart failure (Table⇓).
Conclusion: In this experimental model, the outcomes of CPR were not compromised by preexisting myocardial ischemia.