A Computational Study of the Electrophysiological Substrate in Patients Suffering From Atrial Fibrillation

Figure 1. Overview of AF mechanisms generated by the interplay between functional (electrical remodeling and triggering) and structural factors (structural remodeling generated by the hemodynamics and mechanics dysfunction). We refer to Schotten et al. (2011) for the details of those mechanisms.

Figure 2. CV vector approximation procedure based on a least-squares approach.

Figure 3. Hexahedral meshes with different levels of refinement. The geometry was obtained from Zygote solid 3D heart model (Zygote Media Group Inc., 2014).

Figure 4. Feeding the model with data: numerical approximation of CV field from patient activation map and its projection onto the computational geometry.

Figure 5. LDRBM fibers distribution and projected CV field for the two patients considered in this work.

Figure 6. Comparison of activation maps numerically approximated using different space and time discretizations.

Figure 7. Persistent AF: examples of two localized reentries with different anchoring sites. An anchor point, located in an area of severe slow conduction, allows rotor's stabilization (top). Tissue heterogeneity, instead, force the rotor to travel along a functional line of block (bottom) .

Figure 8. Role of the electrical and structural remodeling in the formation of localized reentries. The formation of functional lines of block occurs in areas of heterogeneous tissue, where the wavefront is likely to meet its tail due to conduction and APD heterogeneity. In areas of severe slow conduction, the rotor stabilize thanks to the low wavefront's speed and the short APD.

Figure 9. Anchor points stabilization in area of severe slow conduction and enhanced electrical remodeling.

Figure 10. Position of localized reentry anchor points or functional lines of block in the analyzed cases generated from the CV field of the persistent patient. The progression of the disease (bottom) generates more anchor points, which sustain the localized reentries.

Figure 11. Non sustained localized reentry in paroxysmal AF.

Figure 12. Effect of a stimulus delivered before (left), after (center) or in the vulnerable window (right). Only in the latter case, the instability creates rotors that might form reentrant circuits.