Abstract 41: Signal Characteristics of 2-d Epicardial Surface and Lead-II ECG During Untreated Ventricular Fibrillation and Cardiopulmonary Bypass Resuscitation
Background: Quantitative waveform measures (QWM) of the ventricular fibrillation (VF) electrocardiogram (ECG) are descriptors of electrical activity of the heart during VF. The correspondence between QWM and the electrophysiology of the myocardium is not fully understood.
Objective: To investigate how the signal characteristics of the chest-surface ECG waveform describe electrical activity of the heart at the epicardial level.
Methods: Six domestic, mixed breed swine were sedated, anesthetized and paralyzed. Mechanical ventilation with room air was provided. Prior to induction of VF, a left-side thoracotomy was performed, the pericardium was excised, and the heart was delivered. Surface ECG was monitored continuously via Lead II ECG. Cardiac arrest was induced with a 3-second 100mA transthoracic shock. A custom-built 9-electrode array with common ground was placed to 1 cm to the right of the LAD approximately 1cm above the apex and manually held in continuous contact with constant pressure. Signal from the Lead II ECG and the 9 epicardial channels were recorded continuously for 15 minutes of untreated VF. After 15 minutes of VF, cardiopulmonary bypass (CPB) was initiated in 2 animals, and signals from the Lead II ECG and the epicardial array were continuously recorded for up to 10 minutes. Frequency spectra were calculated for 8-second data epochs. AMSA, an established QWM, was then calculated from these spectra. AMSA values were compared between Lead II and epicardial channels during the untreated and resuscitation phases.
Results: The trajectory of AMSA versus time was similar between Lead II and epicardial array signals during untreated VF, with AMSA decreasing over time. Reperfusion with CPB resulted in similar recovery of AMSA in both signals. Results are shown in Figure 1.
Conclusion: During untreated VF and subsequent reperfusion, the trajectory of at least one QWM applied at the surface level correlates with activity at the localized epicardial level.
- © 2010 by American Heart Association, Inc.