Low frequency spectral analysis of ventricular fibrillation

Is the frequency of ventricular fibrillation (VF) in the human the same as in the dog, and does the dominant frequency of VF depend on the aetiology of this arrhythmia?  In 4 groups of 4 dogs the dominant frequency of the first 40 seconds of VF was measured using a Bruel and Kjaer spectrum analyzer {0-100 Hz).  For spontaneous VF following coronary artery occlusion (snare technique), the mean dominant frequency was 12.3 ±SEM 0.5 Hz. In reperfusion VF after coronary artery occlusion for 1 hour, the dominant frequency was 11.9±0.5 Hz.  The frequency of VF induced electrically after coronary artery occlusion for 1 hour was 11.4±0.4 Hz (no significant difference between the 3 groups). The frequency of glycoside-induced VF was 6.8±1.4 Hz which was significantly lower than that for the first 3 groups (p<0.02). In all 4 groups the frequency of VF fell significantly over 3 minutes (p<0.02).  The mean dominant frequency of the first 8 seconds of VF did not differ significantly in 13 patients with inferior infarction {6.5±0.2 Hz) from that in 7 patients with anterior infarction (6.5±0.3 Hz), nor did it vary significantly with time from the onset of symptoms of acute ischaemia to VF. In 1 patient, the frequency of VF fell from 6.0 Hz to 3.8 Hz after 90 seconds.  In 2 patients where VF followed directly periods of ventricular tachycardia, low frequencies of VF were recorded (3.75, 4.25 Hz).  The electro- physiological mechanisms of a dominant frequency in VF are not known.  Spectral analysis of VF in the dog does not differentiate myocardial ischaemia from reperfusion or electrically induced VF, but may in cardiac glycoside intoxication.  The higher dominant frequency of VF in the dog than in the human points to limitations of the use of this animal model in the study of VF.