Epicardial mapping of ventricular fibrillation in the human heart during ischaemia and reperfusion

The aim of this study was to map electrical activity over the ventricular epicardial surface during ventricular fibrillation (VF) in the human heart, and to document changes associated with ischaemia and reperfusion. In 5 patients undergoing cardiopulmonary bypass VF was induced by burst pacing, and three 30 s episodes of epicardial activity were recorded at 1 kHz using an epicardial sock with 256 unipolar contact electrodes. The first episode of activity was recorded at the start of VF, the second after 2 minutes of ischaemia, and the third during coronary reperfusion. Following 2 minutes of ischaemia the mean dominant frequency (DF) of the epicardial signals fell from 5.6 Hz to 4.5 Hz, and the mean number of epicardial phase singularities increased from 7.8 to 10.5. Following coronary reperfusion the mean DF increased to 6.5 Hz, but there was no significant change in the mean number of epicardial phase singularities.