Abstract

It has been proposed that ventricular fibrillation (VF) waves emanate from stable localized sources, often called ‘mother rotors’. However, evidence for the existence of these rotors is conflicting. Using a new panoramic optical mapping system that can image nearly the entire ventricular epicardium, we recently excluded epicardial mother rotors as the drivers of Wiggers' stage II VF in the isolated swine heart. Furthermore, we were unable to find evidence that VF requires sustained intramural sources. The present study was designed to test the following hypotheses: (i) VF is driven by a specific region, and (ii) rotors that are long-lived, though not necessarily permanent, are the primary generators of VF wavefronts. Using panoramic optical mapping, we mapped VF wavefronts from six isolated swine hearts. Wavefronts were tracked to characterize their activation pathways and to locate their originating sources. We found that the wavefronts that participate in epicardial re-entry were not confined to a compact region; rather they activated the entire epicardial surface. New wavefronts feeding into the epicardial activation pattern were generated over the majority of the epicardium and almost all of them were associated with rotors or repetitive breakthrough patterns that lasted for less than 2 s. These findings indicate that epicardial wavefronts in this model are generated by many transitory epicardial sources distributed over the entire surface of the heart.

Highlights

  • During ventricular fibrillation, the myocardium is activated by a multitude of complexly interacting electrical wavefronts

  • We studied a total of 17 VF episodes from 6 animals

  • The dominant component persisted from the beginning to the end of the mapped interval, indicating that complete reentrant pathways were continuously present on the epicardium [12] —even though these pathways were not organized as epicardial rotors [10]

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Summary

Introduction

The myocardium is activated by a multitude of complexly interacting electrical wavefronts. A question that has received considerable recent attention is whether the sources of these wavefronts are short lived and widely distributed [1], or whether they are generated by one—or possibly a few—persistent localized sources [2,3,4]. The former scenario is the classic multiple wavelet mechanism and the latter is often called the mother rotor mechanism because permanent rotors are the putative driving sources. The term phase singularity is often used interchangeably with wavebreak [8]

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