Time-frequency analysis of ventricular fibrillation and the effects of amiodarone / 生物医学工程学杂志

This study is to quantify time-varying dominant frequencies in electrocardiogram (ECG) during the ventricular fibrillation (VF). Orthogonal ECG (sagittal, x; transverse, y; and longitudinal, z) and the transvenous two-leads defibrillation systems were set in 19 dogs. Time-frequency analysis was used to assess changes in the dominant frequency within ECG recorded in dogs during trials of 10-30 s of VF. In 4 additional dogs, the dominant frequencies were compared during 10 s of VF before and after administration of amiodarone. Results showed that in the 427 trials of 10 s VF and 335 trials of 30 s VF, average variation in the dominant frequency was considerable, between +/- 12%-18%. The frequencies orthogonal ECG during 10 s VF were distributed symmetrically above and below the mean frequency like a normal distribution. In the 79 trials with administration of amiodarone during 10 s VF in all three ECG, the mean frequencies decreased from 6.5 (x), 7.4 (y) and 7.0 Hz (z) to 6.1, 6.4 and 6.3 Hz (P < 0.01), respectively, and the variation in dominant frequencies decreased from 1.18, 1.38 and 1.19 to 0.98, 1.11 and 1.02 Hz (P < 0.05) respectively. The results confirmed that the frequencies of 10-30 s VF in ECG vary considerably and continuously, and amiodarone decreases this variation.

Hilbert transform analysis of the relation between ventricular fibrillation voltage and the outcome of defibrillation shocks / 生物医学工程学杂志

The objective of this study is to evaluate the correlation between the absolute ventricular fibrillation voltage (AVFV) computed from electrocardiogram (ECG) and the outcome of defibrillation shocks. Orthogonal ECG (sagittal, x; transverse, y; and longitudinal, z) was recorded from 11 dogs during 10 seconds of electrically induced ventricular fibrillation followed by defibrillation shocks with 50% probability of success. The transvenous two-leads defibrillation system was used to deliver defibrillation shocks. The envelope voltage was estimated by using the Hilbert transform. The comparison of the envelope voltages between 236 successful trials and 249 unsuccessful trials did not show any consistent and statistically significant differences. In contrast with the previously reported correlation, the moving average of AVFV was not higher in the successful trials. In the Z direction, the successful trials had lower voltage than did the unsuccessful trials (P < 0.05). These results suggest that the absolute voltage of ECG during ventricular fibrillation is not robustly correlated with the outcome of defibrillation shocks.