• ablation;
  • pulmonary vein isolation;
  • atrial fibrillation;
  • Marshall bundle

The muscular sleeve contained within the ligament of Marshall (Marshall Bundle, MB) has been implicated in triggering and/or maintaining atrial fibrillation. Its connections may form a conduit between the left atrium (LA) and the left pulmonary veins (PVs) and challenge PV isolation attempts. In this case, radiofrequency (RF) ablation at antra of both left PVs failed to affect venous electrical activity. However, isolation of both PVs occurred simultaneously with a single, short (14 seconds) RF energy application at the mitral isthmus. This was delivered at a site recording a complex continuous electrogram (duration 100 ms), interpreted as the site of a single connection between LA and MB. (PACE 2012; 35:e325–e329)