The effects of remodeling with heart failure on mode of initiation of ventricular fibrillation and its spatiotemporal organization

Abstract

Introduction The effect of the heart failure substrate on the initiation of ventricular fibrillation (VF), and its resulting mechanism is not known. The objective of this study was to determine the effects of substrate on VF initiation and its spatiotemporal organization in the heart failure model. Methods Optical action potentials were recorded from LV wedge preparations from either structurally normal hearts (control, n=11) or from congestive heart failure (CHF, n=7), at the epicardial surface, endocardial surface which included a papillary muscle, and a transmural cross section. Action potential duration (APD80) was determined, and VF was initiated. A fast Fourier-transform was calculated, and the dominant frequency (DF) was determined. Results The CHF group showed increased VF vulnerability (69% vs 26%, p<0.03), and every mapped surface showed an APD80 gradient which included islands of higher APDs on the transmural surface (M-cells) which was not observed in controls. VF in the CHF group was characterized by stable, discrete high DF areas that correlated to either foci or spiral waves located on the transmural surface at the site of the papillary muscle. Overall the top 10% of DFs correlated to an APD of 101 ms while the bottom 10% of DFs correlated to an APD of 126 ms (p<0.01). Conclusion In the CHF model, APD gradients correlated with an increased vulnerability to VF, and the highest stable DFs were located on the transmural surface which was not seen in Controls. This indicates that the CHF substrate creates unique APD and DF characteristics.

Role of Apamin-Sensitive Calcium-Activated Small-Conductance Potassium Currents on the Mechanisms of Ventricular Fibrillation in Pacing-Induced Failing Rabbit Hearts

“…16 Recently optical mapping of the epicardial, endocardial, and transmural surfaces in a canine heart failure model showed that stable, high DF areas that correlated with spiral waves or focal activation was observed on the transmural surface at the site of the papillary muscle. 5 The control group showed significantly fewer stable, high DF areas. Non-contact mapping also showed stable reentrant rotors or focal activation in the heart failure model, while unstable rotors characterized the VF in structurally normal hearts.…”

“…The structural and electrical remodeling that occur within the heart failure substrate can lead to an increase in arrhythmogenicity and ventricular fibrillation (VF) 5, 18 . Previous studies have shown that this substrate can have a significant effect on the resulting VF characteristics.…”

“…Previous studies have shown that this substrate can have a significant effect on the resulting VF characteristics. 4, 5 Huang et al showed that with epicardial plaque mapping, VF in heart failure was more organized with a slower activation rate, increased incidence of block, and less reentrant wavefronts compared to structurally normal hearts. 19 Optical mapping of the epicardial surface in sheep hearts with heart failure showed a decrease in DFs and number of rotors as compared to control.…”

“…The mechanisms of VF within the HF substrate have been shown to be dominated by either stable reentrant spiral waves or focal activity, 4 correlating to stable high dominant frequency (DF) areas. 5 This is in contrast to structurally normal hearts which have VF characterized by unstable reentrant spiral waves or multiple waves and transient high DF areas. 4, 5 The underlying mechanisms that support the stability of the reentrant spiral waves within the HF substrate is still unknown.…”

“…5 This is in contrast to structurally normal hearts which have VF characterized by unstable reentrant spiral waves or multiple waves and transient high DF areas. 4, 5 The underlying mechanisms that support the stability of the reentrant spiral waves within the HF substrate is still unknown.…”