Abstract 15939: Correlation between Defibrillation Threshold and Dominant Frequency of Ventricular Fibrillation
Aims. The dominant frequency (DF) in frequency analysis has been considered to represent the objective cycle length and the complexity of the activation during VF. However, knowledge of the mechanisms determining DF is limited, especially in human VF. Thus we studied the character DF of human VF and the relation between DF and the defibrillation threshold (DFT).
Methods. Seventy-two implantable cardioverter-defibrillatior (ICD) patients (46 with structural heart disease (SHD)) and 211 VF were studied. With defibrillation tests, we performed frequency analysis using fast Fourier transformation. Lead II body surface ECG recordings were digitized at a sampling rate of 1,000 Hz by an analog-to-digital converter and stored in a personal computer for off-line analysis. DFT was measured using an up-down algorithm. The correlation between DF and clinical characteristics including DFT was studied.
Results. The mean DF of all induced VFs was 5.2 ± 0.8 Hz. All patients were divided into two groups according to DF: low-DF (DF<5.2 Hz, n=32) and high-DF (DF≥5.2 Hz, n=40). The incidence of SHD was significantly higher in the low-DF group. QRS duration, QT interval and effective refractory period of the right ventricle (RV-ERP) were significantly longer in the low-DF group. Multivariate analysis showed RV-ERP to be the only independent predictor of DF (p=0.002). Excluding patients on group III anti-arrhythmic drugs, which are known to have potent DFT effects, DFT was significantly lower in the low-DF than in the high-DF group (10.5 ± 1.5 J vs. 13.2 ± 5.3 J, p=0.026)
Conclusions. DF was affected by underlying heart diseases, cardiac function, conduction velocity and action potential duration. Among these factors, action potential duration was the only independent predictor of DF. VF with high DF tends to require greater energy to achieve defibrillation.
- © 2012 by American Heart Association, Inc.