Fast Fourier Transform Analysis of Ventricular Fibrillation Intervals to Predict Ventricular Refractoriness and Its Spatial Dispersion

Abstract

A technique of fast Fourier transform analysis has been used to derive mean ventricular fibrillation (VF) intervals, and to confirm that these VF intervals predict ventricular refractory periods. Twenty episodes of VF were induced by a rapid ventricular pacing in 12 sheep. VF activations in a 10-second period were simultaneously acquired from 64 epicardial sites with an electrode sock. The VF electrograms were analyzed by a fast Fourier transform analysis. The dominant peak frequency of the VF spectrum in each epicardial site was converted into milliseconds and served as a mean VF interval. The dominant peak frequency of VF electrograms ranged from 8.1 to 11.5 Hz, and the corresponding mean VF intervals were 87 to 124 ms. In five sheep, the mean VF intervals and the effective refractory periods were determined by the extrastimulus technique obtained from 29 epicardial sites. There was a very good correlation between the two parameters when the effective refractory periods were determined at a basic cycle length of 300 ms (r = 0.89, P < 0.001) and 400 ms (r = 0.87, P < 0.001), respectively. VF was induced twice in eight sheep. The maximum difference in the mean VF intervals between the two VF episodes in the same sheep was 3 ms (P > 0.05). In conclusion, mean VF intervals determined by the fast Fourier transform analysis have a good reproducibility and a good correlation with ventricular refractory periods measured by the classic extrastimulus technique. The mean VF intervals could serve as an index of ventricular refractoriness.

Non-invasive evaluation of ventricular refractoriness and its dispersion during ventricular fibrillation in patients with implantable cardioverter defibrillator

“…The significance of disparity in refractoriness in the genesis of tachyarrhythmias has been emphasized by several experimental studies [6,8,9]. In the present study, the dispersion of the 10th percentile VF intervals between the RV apex and posterior LV is markedly larger than the previously reported dispersion of repolarization in patients without malignant ventricular arrhythmias [14,15].…”

“…However, the VERP during VF could not be tested using this technique. Fibrillation intervals have been used as an index of local refractoriness and shown to correlate well with the local atrial and ventricular refractoriness determined using extrastimulus technique in animal [4,6-8] and human subjects [5,9] in serval previous studies. This method is based on the assumption that during fibrillation, cells are reexcited by one of many multiple wavelet as soon as their refractoriness ends and recovers their excitablity.…”

Life Span of Ventricular Fibrillation Frequencies

“…Alternatively, frequency blobs can be due to a complex meandering reentrant circuit. Previous studies 5,7,23,35 indicated that the action potential duration (APD) and refractory period at each site influences the VF frequencies and activation intervals recorded from the same site. Hence, conditions that reduce the dispersion of APDs are expected to depress the number of VF frequency blobs because either a single dominant rotor is formed or multiple rotors in different location share the same frequency.…”

Characteristics of Induced Ventricular Fibrillation Cycle Length in Symptomatic Brugada Syndrome Patients

“…30 The local refractory period influences VF dynamics by limiting the range of VF frequency. 31 The DF of short intervals of induced VF is highly reproducible.…”