Provocative Cases -> Teaching Case Reports D-PO03 - Poster Session III (ID 48) Poster

D-PO03-056 - Direct Epicardial Recordings Of Bachmann Bundle During Refractory Mitral Flutter With Endocardial Block (ID 299)

 L. Yu: Nothing relevant to disclose.


Background: Nontransmural lesions sets are common causes of recurrent peri-mitral atrial flutter (PMAFL). Direct epicardial recordings of Bachmann’s bundle (BB) may provide mechanistic evidence for the difficulties associated with creating durable anterior block.
Objective: To report a case of PMAFL with BB serving as an epicardial bridge over a prior blocked endocardial anterior linear lesion set.
Results: A 67-year-old man presented with atrial tachycardia recurrence despite three prior procedures of pulmonary vein isolation and linear ablations. PMAFL has been previously detected with a termination at the anterior deceleration zone. In the present procedure, an activation mapping was performed for the on-going atrial flutter and indicated a recovered PMAFL. However, the prior anterior linear lesion was blocked with extensive low voltage scar (<0.1mV). Therefore, an epicardial breakthrough was suspected. A Decapolar catheter (Deca) navigating to the epicardial BB via a percutaneous epicardial approach exhibited a deceleration zone, which bridged the flutter propagation following the opposite endocardial surface. The fragmented electrogram (EGM) on Deca (3,4) was captured by pacing with 350ms, which demonstrated a concealed entrainment, suggesting that the epicardial BB was “in” the flutter circuit. Ablation targeting the fragmented epicardial EGM prolonged the CL immediately, with subsequent flutter termination to sinus rhythm lateral to this site.
Conclusion: BB may serve as an epicardial bridge across the anterior left atrium, which highlights the need to consider 3-D activation in refractory cases of atrial flutter with prior endocardial block.