Abstract
Radiofrequency catheter ablation of inferior atrial ganglionic plexi frequently results in vagal denervation of the atrioventricular (AV) node. The effective sites are, however, considerably variable.
We prospectively sought the left atrial (LA) ablation site with the maximum effect on AV nodal modulation.
The study included 16 patients (age: 46±14 years, 56% males) who underwent cardioneuroablation for recurrent reflex cardioinhibitory syncope in general anesthesia. After targeting the superior paraseptal ganglionic plexi and achieving the denervation of the sinus node, study ablations were performed at the bottom of the LA to accomplish the AV nodal denervation (Figure). Five equidistantly distributed ablation lesions (30W / 30s / 20ml/min) were created on the virtual line connecting inferior ostium of right inferior pulmonary vein (RIPV) and inferior mitral annulus (MA). Lesions were centered symmetrically relative to the posterior mid-left-atrial line. They were numbered in ascending order from #1 (more septal, closer to the RIPV) to #5 (more lateral, closer to the MA). Patients were randomly (1:1) assigned to mutually opposite direction of ablation (from site #1 to #5 or from site #5 to #1). The response of heart rhythm to extracardiac vagal nerve high-frequency stimulation (50Hz/0.05ms/1V/kg [<70V]/5s) were recorded at baseline and after each radiofrequency energy delivery.
Study protocol ablations overall resulted in elimination or attenuation of inducible AV block (maximum R-R interval: 2.9±2.8 vs. 5.2±2.4s, P<0.001). Temporal development of effect with the progression of ablation is shown in the Figure indicating that the most lateral lesion alone produces the maximum effect. The AV nodal denervation was incomplete after per-protocol ablations in 7/16 patients. In the majority of them, the final success was achieved by extension of ablation lesion toward the inferior mitral annulus either endocardially or via the proximal coronary sinus.
Ablation of perimitral region of the inferior LA conveyed the maximum effect in terms of AV nodal denervation.
Type of funding source: None
