4.2 AF rotors and the PV antrum
Guillem et al. reported that rotors could be initiated by a focal
ectopic discharge and wavefront break.11 The other
previous studies demonstrated that the sleeve of the PV was thickest at
the venoatrial junction and often consisted of 2 or more
layers.12,13 Those anatomical findings indicated the
presence of thick and anisotropic myocardial structures in the PV
antrum. Thicker parts of the PVs with anisotropic properties may provide
the substrate for a functional line of block during rotor activation. In
this study, the NPAs were mostly found around the PV antrum, which was
completely consistent with the previous study.10Furthermore, the tissue properties of the NPAs around the PV antrum also
predominantly consisted of G2 and subsequently G1. The tissue properties
of G1 indicated heterogenous and healthy tissue and this heterogeneity
might have been caused by the wall thickness and anisotropic myocardial
structures but not myocardial fibrosis.