Abstract P27: Recovery of Electrocardiogram Organization After Prolonged Ventricular Fibrillation and Cardiopulmonary Bypass
Background: During prolonged ventricular fibrillation (VF), the electrocardiographic (ECG) waveform undergoes a progressive deterioration in organization that can be quantified. Metrics of VF ECG organization, including the Scaling Exponent (ScE), have been correlated with defibrillation success.
Purpose: We sought to examine the effect of reperfusion on the VF ECG waveform after varying lengths of prolonged, untreated cardiac arrest under optimal perfusing conditions created by administration of cardiopulmonary bypass (CPB).
Methods: Twelve domestic mixed breed swine were sedated, anaesthetized and paralyzed. Mechanical ventilation with room air was provided. Large diameter bypass catheters were placed in the right external jugular vein and right femoral artery for CPB. VF was induced with a 3-second 100mA transthoracic shock and left untreated for 15, 20, 25, or 30 minutes, followed by 10 minutes of centrifugal pump CPB (Bard CPS). Continuous Lead II ECG was recorded with an electronic data acquisition system (Power Lab, ADInstruments). A quantitative measure of the VF ECG waveform, ScE, was calculated continuously for the untreated VF and bypass periods.
Results: Three animals were assigned to each VF duration group. The mean ScE at start of VF were similar across all groups (1.32 +/− 0.02). Figure 1⇓ shows the progression of the ScE by group from the start of untreated VF to the end of CPB. ScE recovered to VF starting values in the 15 and 20 minute groups but remained high in the 25 and 30 minute groups.
Conclusion: ECG organization is more responsive to reperfusion after shorter durations of VF. ECG may be useful for titrating CPB duration before defibrillation.