Aims: Radiofrequency ablation at the posterior papillary muscle (PM) significantly reduced ventricular fibrillation (VF) inducibility in rabbits and dogs, suggesting that PM may be involved in the generation of VF. However, the effect of ablation at the PM on VF inducibility remains unknown in normal intact swine hearts because in this species radiofrequency energy delivered at PM provoked incessant VF.
Methods and results: Twelve anesthetized swine underwent median sternotomy. Under the ultrasonographic guidance, chemical ablation was performed via injection of dehydrated alcohol into the base of the posterior PM (group PM, n = 6) or anterior wall (control group, n = 6) in the left ventricle. Ventricular fibrillation inducibility and mitral valve function were measured pre- and post-ablation. Hearts were explanted and the ablated myocardium was stained with haematoxylin and eosin. Ventricular fibrillation inducibility was significantly decreased from 100 ± 0% pre-ablation to 11.9 ± 7.8% post-ablation in group PM (P = 0.001), whereas it was not statistically different in the control group (100 ± 0 vs. 92.9 ± 7.1%, pre-ablation vs. post-ablation). Haemorrhage and cellular necrosis was observed in the centre of ablated myocardium and no significant mitral regurgitation was observed following ablation at the posterior PM.
Conclusion: Alcohol ablation of the left posterior PM reduced VF inducibility in normal intact swine hearts, with no significant mitral regurgitation. This suggests that the posterior PM may be involved in the generation of VF, and the recurrence of VF may be prevented by chemical ablation at the posterior PM.