Endocardial activation during ventricular fibrillation in normal and failing canine hearts

Abstract

Because congestive heart failure (CHF) promotes ventricular fibrillation (VF), we compared VF in seven dogs with CHF induced by combined myocardial infarction and rapid ventricular pacing to VF in six normal dogs. A noncontact, multielectrode array balloon catheter provided full-surface real-time left ventricular (LV) endocardial electrograms and a dynamic color-coded display of endocardial activation projected onto a three-dimensional model of the LV. Fast Fourier transform (FFT) analysis of virtual electrograms showed no difference in peak or centroid frequency in CHF dogs compared with normals. The average number of simultaneous noncontiguous wavefronts present during 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 "turnover" 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. Thus the fundamental frequency characteristics of VF are unaltered by CHF, but dilated abnormal ventricles sustain fewer active wavefronts than do normal ventricles.

Mechanisms of Ventricular Fibrillation in Canine Models of Congestive Heart Failure and Ischemia Assessed by In Vivo Noncontact Mapping

“…When the heart failure dog model also included a healed myocardial infarction, the DFs during VF were similar to those of controls, but the heart failure model had a decreased number of wave fronts as observed with noncontact mapping. 37 The present study shows data that supports the finding by Huang et al and Moreno et al by also showing a slower activation rate in the heart failure animals because, on average, the DFs were lower than in the control or ischemia animals. However, the present study also showed that a stable mechanism can exist in the CHF dogs of either reentry or focal.…”

Effect of remodelling, stretch and ischaemia on ventricular fibrillation frequency and dynamics in a heart failure model

“…Previous experimental studies in the open-chest dog showed that VF in HF is associated with a significantly lower number of wavefronts and reentrant circuits than in normal hearts [2,7]. Our data showing decrease in the density of SPs and rotors in the ovine model of HF confirm those results.…”

“…During virtual endocardial mapping, Pierpont et al [7] showed no difference in peak frequency between HF and normal hearts. In contrast, Huang et al [2], using an epicardial multi-electrode plaque reported a 27% reduction in activation rate in HF.…”

“…In addition, in failing hearts, passive electrical properties may be impaired as gap junction density is reduced [6]. Whole animal studies designed to evaluate effects of HF remodelling on VF dynamics showed a significant decrease in the number of fibrillating waves in HF animals with conflicting results regarding VF frequencies [2,7].…”

The Mechanisms of an Increased Dominant Frequency in the Left Atrial Posterior Wall During Atrial Fibrillation in Acute Atrial Dilatation

“…When two wavefronts collided and fused, they were then counted as one. Conversely, when a wavefront bifurcated, two wavefronts were present from then on 20,21 . To quantify the number of distinct wavefronts present at any time on the endocardial surface of the atrium, color potentials projected onto the electroanatomic map of the atrium were set such that white represented a small range of amplitudes indicative of the most negative potentials present, and a rainbow spectrum represented progressively more positive potentials.…”