Key result
Rapid pacing from the septum captured up to 80% of the atrial surface in a homogeneous substrate, but heterogeneities in vagal activation or repolarization degraded the ability to capture AF.
Why the study?
Does atrial substrate influence the ability to capture atrial fibrillation during rapid pacing from the septum in biophysical models?
Does atrial substrate influence the ability to capture atrial fibrillation during rapid pacing from the septum in biophysical models?
Computational modeling demonstrates that atrial fibrillation substrate significantly affects the efficacy of rapid pacing, indicating that therapeutic pacing responses may be highly patient-specific.
Substrate heterogeneities may limit septal pacing for AF capture in models; leaves open patient-specific therapeutic translation.
AIMS: Preliminary studies showed that the septum area was the only location allowing local capture of both the atria during rapid pacing of atrial fibrillation (AF) from a single site. The present model-based study investigated the influence of atrial substrate on the ability to capture AF when pacing the septum. METHODS AND RESULTS: Three biophysical models of AF with an identical anatomy from human atria but with different AF substrates were used: (i) AF based on multiple wavelets, (ii) AF based on heterogeneities in vagal activation, (iii) AF based on heterogeneities in repolarization. A fourth anatomical model without Bachmann's bundle (BB) was also implemented. Rapid pacing was applied from the septum at pacing cycle lengths in the range of 50-100% of AF cycle length. Local capture was automatically assessed with 24 pairs of electrodes evenly distributed on the atrial surface. The results were averaged over 16 AF simulations. In the homogeneous substrate, AF capture could reach 80% of the atrial surface. Heterogeneities degraded the ability to capture during AF. In the vagal substrate, the capture tended to be more regular and the degradation of the capture was not directly related to the spatial extent of the heterogeneities. In the third substrate, heterogeneities induced wave anchorings and wavebreaks even in areas close to the pacing site, with a more dramatic effect on AF capture. Finally, BB did not significantly affect the ability to capture. CONCLUSION: Atrial fibrillation substrate had a significant effect on rapid pacing outcomes. The response to therapeutic pacing may therefore be specific to each patient.
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Rusu et al. (2014) studied Atrial fibrillation. Rapid pacing from the septum vs. Different AF substrates was evaluated on Local capture of atrial fibrillation. Rapid pacing from the septum captured up to 80% of the atrial surface in a homogeneous substrate, but heterogeneities in vagal activation or repolarization degraded the ability to capture AF.
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