Organized Frequency Structure of Electrocardiogram During Long-Duration Ventricular Fibrillation Under Experimental Conditions
Sovremennye tehnologii v medicine
The aim of the investigation is to study the frequency structure of electrocardiogram (ECG) during long-duration ventricular fibrillation (VF) in the canine heart using fast Fourier transform in the frequency range of 1-40 Hz. Materials and Methods. ECG has been recorded in 10 dogs before VF and during VF. No pathological changes were revealed on ECGs before VF. The VF was induced by a brief (2 s) application of alternating current (30 V; 50 Hz) to the heart region. Spectral analysis of ECG in
... analysis of ECG in VF was carried out using fast Fourier transform in five frequency bands: very low frequencies (1-3 Hz), low (4-7 Hz), middle (8-12 Hz), high (13-17 Hz), and very high frequencies (18-40 Hz). Spectral power (amplitude) and specific gravity of oscillations were determined in all five frequency bands. Results. ECG in VF is characterized by dominant frequency structure. At minute 1 of VF the most significant changes have been observed in the frequency structure with transition from domination of high frequency oscillations (13-17 Hz) to domination of middle frequency oscillations (8-12 Hz) and after that to domination of low frequency oscillations (4-7 Hz). At minutes 2-10 of VF domination of low frequency oscillations is replaced by domination of low and middle frequency ones. Total spectral power of oscillations in the range of 1-40 Hz shows insignificant changes at minute 1 of VF and significantly decreases at minutes 12-10 of VF. Conclusion. Dominant frequency structure points to indicates electrical activity in VF. The results of the paper can be used in algorithms for automatic detection of VF with dominant frequency structure. Organized activity in VF provides a good theoretical framework to search for a new method of sequential rhythmic defibrillation using a series of relatively weak but rhythmic organized stimuli.