Fibrillation frequency and ventricular defibrillation

In a clinical study of 49 patients with acute ischemie heart disease poor success rates from ventricular defubrillation were associated with a low dominant frequency of ventricular fibrillation (generally < 5 Hz) as determined by Fast Fourier Transform analysis of the body surface ECG. Experimental studies in the dog and pig are in accord with these observations, and indicate that the dominant frequency of ventricular fibrillation is reduced both by a long duration of fibrillation in a normal heart, and by some causes of ventricular fibrillation (ouabain or potassium toxicity in the dog, secondary fibrillation in man).