Pranav Bhagirath

102 Chapter 5 by a recent simulation study on the effects of mechanical deformation on cardiac bioelectrical activity where myocardial stretch resulted in an increased dispersion of repolarization time and action potential duration (18) . In addition, clinical observations have also described a relation between increased arrhythmogenicity of the LA with increasing stretch between the LA and PV junction (19) . In line with these findings it can also be hypothesized that larger positive remodeling (reduction in LASP) leads to better connectivity between the applied ablation lesions (‘closing of the remaining gaps’). Due to more complete and gap free isolation lines, the ectopic foci localized in the pulmonary veins are unable to initiate and maintain AF ( figure 5 ). This is supported by the observation that pulmonary vein isolation during the acute phase is caused due to a combination of necrosis and edema (20) . The resolution of edema may lead to reconnection of the PV’s and could result in recurrence of AF. The results of the current study underline the importance of including the LASP as a parameter for selection of candidates suitable for a repeat ablation procedure. Ablation Post-procedural Low LASP (reversed remodeling) High LASP (no remodeling or increase) = fibrosis = edema Resolution of edema increased distance Figure5. Schematic representation of the potential mechanismrelated to LASP and successfully isolated PV’s. The left panel of figures depicts the sites of ablation lesions (orange and green dots) on the pulmonary vein (blue cylinder). The right panel depicts the change in PV size due to reverse remodeling and its impact on the proximity of ablation lesions following the resolution of ablation induced edema. The PV’s of patients with a higher LASP retain their original size or may undergo an increase in size (dotted semi-circle) which, due to increased distance between ablation lesions, may be an additional factor that contributes to incomplete electrical isolation (gaps) (star indicates PV ectopy; arrows indicate electrical leaks).