Organized Structure of Ventricular Fibrillation during Prolonged Heart Perfusion in Dogs.

The aim of the study was to identify the organized ventricular fibrillation (VF) activity in the dog heart and characterize its quantitative parameters during prolonged heart perfusion. MATERIALS AND METHODS: A total of four experiments on isolated dog's hearts perfused with the blood of a supporting dog were performed. Episodes of VF were recorded in the form of an electrogram followed by a spectral analysis by the fast Fourier transform in the range of 0.5-15 Hz. The frequency, spectral power (amplitude), and relative weight (%) of the 1st, 2nd, and 3rd highest amplitude oscillations were determined (frequency - mode; amplitude, relative weight - M±SEM; n=120). RESULTS: In the perfused dog heart, VF was characterized by an organized activity, as evidenced by the dominant structure of the oscillation frequencies. Oscillations with a frequency of 9-10 Hz (occurring in 1/10 of the 0.5-15 Hz range) represent 42-44% of the spectral power and dominate the structure of the oscillation frequencies. The frequency and spectral power of the dominating oscillations proved to be stable thus indicating that under perfusion, VF did not cause disturbances in the heart organized activity. CONCLUSION: Our experimentation with isolated perfused hearts revealed the patterns of VF that could not be revealed in situ under conditions complicated by nerve factors and ischemia in VF. The results of the work are protected with a patent which is applicable for VF diagnosis in implantable defibrillators.

Dominant and Non-Dominant Frequency Structure of Evoked Ventricular Fibrillation in Dogs with Myocardial Ischemia.

The first 10 min of electrically provoked ventricular fibrillation in dogs with ischemic heart disease were characterized by organized myocardial activity evidenced by the dominant ECG frequency structure. During the first 2 min of ventricular fibrillation, low-frequency oscillations (4-7 Hz) dominated, while on min 3 to 10 after the onset of fibrillation, the dominant frequencies were low and medium (4-12 Hz). After 10-min fibrillation, the oscillations became non-dominant. Thus, ischemic myocardium maintains the organized structure of ventricular fibrillation for the first 10 min, which is important for the development of automatic diagnostics of abnormal cardiac activity in humans.

Dominant and Non-Dominant Structure of Ventricular Fibrillation in Canine Heart.

Organized activity of the myocardium manifested in dominant frequency structure of EСG was typical of the first 10 min of ventricular fibrillation in canine heart. The first minute of fibrillation was characterized by the most pronounced changes in the structure of oscillation frequency and transition from domination of high frequency oscillations (13-17 Hz) to domination of medium (8-12 Hz) and then low frequency (4-7 Hz) oscillations. The second minute was characterized by transition from domination of low frequency oscillations to domination of low and medium frequency oscillations; minutes 3-10 were characterized by domination of low and medium frequency oscillations; after 10 min, non-dominant ventricular oscillations were recorded.