Endocardial activation during ventricular fibrillation in normal and failing canine hearts

Because congestive heart failure (CHF) promotes ventricular fibrillation (V F), we compared VF in seven dogs with CHF induced by combined myocardial in farction and rapid ventricular pacing to VF in six normal dogs. A noncontac t, multielectrode array balloon catheter provided full-surface real-time le ft ventricular (LV) endocardial electrograms and a dynamic color-coded disp lay of endocardial activation projected onto a three-dimensional model of t he LV. Fast Fourier transform (FFT) analysis of virtual electrograms showed no difference in peak or centroid frequency in CHF dogs compared with norm als. The average number of simultaneous noncontiguous wavefronts present du ring VF was higher in normals (2.4 +/- 1.0 at 10 s of VF) than in CHF dogs (1.3 +/- 1.0, P < 0.005) and decreased in both over time. The wavefront "tu rnover" rate, estimated using FFT of the noncontiguous wavefront data, did not differ between normals and CHF and did not change over 5 min of VF. Thu s the fundamental frequency characteristics of VF are unaltered by CHF, but dilated abnormal ventricles sustain fewer active wavefronts than do normal ventricles.