Po-05-236 atrial non-capture at ganglion plexi site during cardioneuroablation

Cardioneuroablation (CNA), identification and radiofrequency ablation of ganglionated plexi (GP), has emerged as a viable treatment modality for hypervagal mediated disorders such as cardioinhibitory syncope. CNA is under active investigation and much remains to be learned. We present the observation of atrial non-capture at a GP site with vagal stimulation during a CNA procedure N/A The patient is a 12-year-old female with a history of focal seizures admitted for worsening seizure burden despite escalation of her medical therapies. During hospitalization, bedside monitoring recorded multiple episodes of heart block (ventricular rates in the 20's) and two episodes of ictal high-grade AV block, resulting in 7-10 seconds of asystole. To expand therapy options, including the potential for a vagal nerve stimulator, she was recommended for CNA. The patient was placed under general anesthesia and access obtained via the right femoral vein. Baseline electrophysiology findings were as follows: RR 649 ms, PR 135 ms, AH 58 ms, HV 58 ms, and QT 353 ms. The IVC, SVC, right atrial and left atrial geometry shell was drawn using the EnSite NavX precision cardiac mapping system. The mapping catheter was then advanced into the internal jugular vein to the level of the carotid bifurcation and the vagus nerve stimulated at 50 Hz, easily inducing AV block resulting in more than 8 seconds of asystole. Utilizing complex, fractionated atrial bipolar electrograms (CFAE), the GP sites were identified. While pacing at the left inferior GP site, vagal stimulation resulted in expected transient asystole. Interestingly, there was corresponding, transient atrial noncapture during vagal stimulation (Figure 1). Thereafter, the aortic-SVC and left inferior GP sites were successfully ablated. Post ablation, vagal stimulation resulted in only mild sinus slowing and the longest induceable pause was one second. The patient tolerated the procedure well with no complications. The entire procedure was performed without fluoroscopy. Cardioneuroablation is an emerging treatment modality for hypervagal cardioinhibitory syndromes. Identification of GP sites is critical for success. We speculate that vagal stimulation raises the capture threshold of atrial tissue at GP sites. This may be useful in fine tuning ablation sites during CNA. It is curious if this phenomenon is specific to GP sites. Beyond CNA, this finding may have implications for lead placement during pacemaker implantation.