Dear Sir,
We thank Dr Pachon for his interest in our manuscript.1 While we acknowledge that the concept of autonomic ablation for treatment of bradyarrhythmias was first proposed by Dr Pachon’s group,2,3 we would like to draw the reader’s attention to the methods of identifying the ganglionated plexi (GP). The original description by Dr Pachon’s group was based on Fast-Fourier Transform (FFT) analysis of the endocardial atrial electrograms, with GP sites showing fractionated signals and shift of the FFT spectrum to the right. In contrast, the study by Yao et al.4 used high-frequency stimulation to identify the GP sites. The actual sites and extent of ablation also differed between the two studies. As the two techniques have not been compared with each other, it remains unclear which is the preferred technique. These differences highlight the need for more research to understand the intricacies of the cardiac autonomic nervous system and how its manipulation can be used to treat vexing cardiovascular diseases, such as neurocardiogenic syncope.