Organized structure of ventricular fibrillation in dogs with myocardial ischaemia.

Abstract

The purpose of the investigation: To reveal and study the organized activity of ventricular fibrillation (VF) in dogs with myocardial ischaemia before VF using the spectral analysis of electrocardiogram (ECG) in VF by the method of Fast Fourie Transform (FFT).

Methods: Four experiments was carried on dogs with myocardial ischaemia before VF. The ECG in dogs was recorded during 2 minutes before VF and within the first 10 minutes of VF, which was caused under stimulation the chest of the dog by alternating current (50 Hz; 30 V) within 2-3 seconds. The spectral analysis of ECG in VF was carried using the method of FFT in 5 frequency bands: very low frequencies (1-3 Hz), low (4-7 Hz), medium (8-12 Hz), high (13-17 Hz) and very high frequencies (18-40 Hz). The spectral power (mV) and proportion (%) of oscillations was determined in five-second intervals of ECG during VF in the range of the very low frequencies, low, medium, high and the very high frequencies.

Results: The low frequency oscillations of 4-7 Hz dominated during the first minute of VF in dogs with myocardial ischaemia before VF. Domination of the low frequency oscillations was replaced by domination of the low and medium frequency oscillations of 4-12 Hz during the second and third minutes of VF. The low and medium frequency oscillations dominated at 4-10-th minutes of VF

Conclusion: The first 10 minutes of VF in dogs with myocardial ischaemia before VF are characterized by an organized activity that confirmed by dominant frequency structure of the ECG oscillations. Organized structure of VF is resistant to ischaemia: an organized structure persisted under the influence of 10 minutes of myocardiual ischaemia during VF.