Figure 1.

(A) Hierarchical stages of the ANS from the central to the peripheral system. First, a mapping catheter is used to pace in the endocardium of the left atrium for four beats to ensure that there is no ventricular capture. HFS is then delivered at 20 Hz, 12 V. Asystole occurs almost immediately after starting HFS. This is due to direct AV dissociation or via stimulation of the RLGP acting as the common “gateway” to the AV node. During HFS and AV dissociation, there is continued atrial activity as observed in CS 3 to 4. Due to the high voltage output, the Map electrogram only shows output signals during pacing and HFS. The RR interval recovers following cessation of HFS. This site was determined as an A‐AVD‐GP site. (B) An intracardiac recording of determination of a B‐AVD‐GP site. We have performed HFS with the same parameters as (A) but for 10 seconds. The mean of 10 RR intervals preceding HFS was 952 milliseconds. We then measured the total time duration between the first R after starting HFS and the first R after cessation of HFS (HFSRR) and averaged this to calculate the mean RR interval (1610 milliseconds). There was increase in more than 50% of the RR interval during HFS from the baseline that determined it as an AVD‐GP site. However, there was no asystole like in A‐AVD‐GP. This was therefore determined as a B‐AVD‐GP site. A‐AVD‐GP, asystole atrioventricular dissociating ganglionated plexus; ANS, autonomic nervous system; AV, atrioventricular node; AVD‐GP, atrioventricular dissociating ganglionated plexus; B‐AVD‐GP, bradycardia atrioventricular dissociating ganglionated plexus; BP, blood pressure; CS, coronary sinus; HFS, high frequency stimulation; GP, ganglionated plexus; LA, left atrium; RLGP, right lower ganglionated plexus [Color figure can be viewed at wileyonlinelibrary.com]