Abstract
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.
Highlights
Unlike coordinated heart contractions that support hemodynamics, ventricular fibrillation (VF) is characterized by uncoordinated contractions of individual myocardial fibers which unable to maintain hemodynamics and lead to death [1, 2]
VF in the isolated dog heart is characterized by the dominant structure of oscillation frequencies, which indicates an organized myocardial activity
The dominance of VF oscillations with a frequency of 9–10 Hz reflects, apparently, the synchronized activity of cardiomyocytes generating action potentials with a frequency of 9–10 Hz. This hypothesis is supported by the observation that cardiomyocytes generated action potentials with a frequency of 9–10 Hz in the first seconds of the VF [11, 12]; in this first short period, the myocardium is not ischemic yet, thanks to resources of ATP and oxygen [22, 28]
Summary
Unlike coordinated heart contractions that support hemodynamics, ventricular fibrillation (VF) is characterized by uncoordinated contractions of individual myocardial fibers which unable to maintain hemodynamics and lead to death [1, 2]. VF-associated sudden heart death contributes to 15–20% of deaths worldwide [3,4,5]. Ventricular fibrillation is traditionally considered to be a disorganized process [6,7,8,9], organized activity in VF have been recently found [10,11,12]. This activity decreases during the first 8–10 min of VF, and VF becomes disorganized [13,14,15]. It has been found that this decrease in the organized activity is
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