Discussion

The anatomy of the vagus nerves as they course through the thorax, as well as the cardiac autonomic nervous system anatomy, is germane to the pathophysiology and treatment described. Within the chest, the right vagus nerve runs posterior to the superior vena cava and right mainstem bronchus and then innervates cardiac and oesophageal plexuses, providing parasympathetic input to the heart and efferent (smooth muscle) and afferent (sensory) fibres to the oesophagus. ^{Reference Kenny and Bordoni1} The left vagus nerve descends into the thorax between the left common carotid and subclavian arteries, gives rise to the left recurrent laryngeal nerve, and then provides innervation to both cardiac and oesophageal plexuses. ^{Reference Kenny and Bordoni1} Thus, there is anatomic basis for parasympathetic reflex activation in response to strong afferent signalling from the oesophagus, i.e. significant visceral distension or an underlying pathologic process. ^{Reference Moore, Lee, Garcia and Krantz2} The intrinsic cardiac nervous system includes ganglionated plexi, which exert preferential control over specific areas within the heart. ^{Reference Giannino, Braia and Griffith Brookles3} The left atrial ganglia (near the pulmonary veins) primarily affect atrioventricular node function and thus are interventional targets in patients with inducible heart block. ^{Reference Stavrakis, Nakagawa, Po, Scherlag, Lazzara and Jackman4}

Although deglutition (swallow) syncope in adults was first described in the 18th century, ^{Reference Spens5} the first case report in paediatrics was not published until 1986. ^{Reference Woody and Kiel6} The relative paucity of data in children likely has to do with increased symptom burden in adults, due in turn to a higher prevalence of contributing baseline cardiac and oesophageal disease. While a “cornucopia” of treatment options has been proposed for adults, including diet modification, ^{Reference Patsilinakos, Antonatos and Spanodimos7} medications, ^{Reference Patsilinakos, Antonatos and Spanodimos7} cardioneural ablation, ^{Reference Yoneda, Shizuta, Makiyama, Masunaga, Hoshida and Kimura8} and pacing, ^{Reference Garg, Girotra, Glasser and Dutta9} treatment proposals for children are sparse. In the most recent paediatric case report on the subject, the authors utilised a transvenous pacemaker ^{Reference Manu and Aziz10} and commented on only 3 weeks of follow-up. Much has been learned from the adult experience since that time and deserves discussion.

Cardioneural ablation for parasympathetically induced bradyarrhythmias, including atrioventricular block, was first reported in 2005. ^{Reference Pachon, Pachon, Lobo, Pachon, Vargas and Jatene11} Over time, the importance of the posteromedial left ganglionic plexus in patients with AV block has been emphasised; while the superior right plexus principally modulates the sinus node, this leftward plexus in close anatomic proximity to the AV node is thought to be its final direct parasympathetic input. ^{Reference Stavrakis, Nakagawa, Po, Scherlag, Lazzara and Jackman4} Aksu et al. reported a case series of 31 patients with successful treatment of functional atrioventricular block via ablation targeting the posteromedial left ganglionic plexus. ^{Reference Aksu, Gopinathannair, Bozyel, Yalin and Gupta12} Furthermore, results from a recently published multicenter trial, encompassing 15 centres and 205 adult patients (mean age 47 ± 17 years), are encouraging, with less than 5% minor complication rate, 78% of patients free of syncope at over 1 year of follow-up, and 97% freedom from pacemaker implantation. ^{Reference Tung, Pujol-Lopez and Locke13} By contrast, there are only a few reports of the use of cardioneural ablation in children, with a recent single-centre series describing only six patients with excellent results at 6-month follow-up. ^{Reference Choi, Hong and Moak14} Complications and long-term maladaptive effects are also a concern in paediatric patients, with recent reports of post-ablation inappropriate sinus tachycardia hopefully not foretelling of further complications from attenuated parasympathetic tone on the young heart. ^{Reference Chelikam, Katapadi and Pothineni15,Reference Kulakowski and Piotrowski16}

Compared to the “slim-pickings” of data on paediatric cardioneural ablation, a “smorgasbord” of reports on ventricular pacing for inducible atrioventricular block has been presented. ^{Reference Mitra, Ludka, Rezkalla, Sharma and Luo17–Reference Morita, Kasai, Kitai, Fujita and Kondo21} Even in clinical trials, however, pacing is often reported to incompletely treat syncope. ^{Reference Behnoush, Yazdani and Khalaji22} Hemodynamically this would be expected, as a vasodepressor component to symptoms (vasovagal syncope) often is present instead of pure cardioinhibition. ^{Reference Gopinathannair, Salgado and Olshansky23} Furthermore, implantation of a conventional transvenous pacemaker in a young patient places them at risk for long-term device-related complications (Figure 3). ^{Reference Takeuchi, Toyohara and Yagishita24} Therefore, a leadless system, especially in a patient such as ours with the primary conduction problem of AV block, is enticing. The Medtronic Micra™ leadless pacemaker was approved for use in the United States in 2016 ^{Reference El-Chami, Merchant and Leon25} and has shown excellent short-term success. ^{Reference El-Chami, Al-Samadi and Clementy26} In paediatrics, small series with relatively short-term follow-up have been published. ^{Reference Shah, Borquez and Cortez27,Reference Wong, Yeh, Davidson, Sunderji, Dayan and Cortez28} Use of leadless pacing specifically for deglutition syncope has been described in adults, ^{Reference Brieger, Tofler and Chia29} but not in paediatrics to date. Finally, when considering pacing, sensor-based systems such as closed-loop stimulation (Biotronik, Berlin, Germany) are a consideration. ^{Reference Occhetta, Bortnik and Audoglio30} Closed-loop stimulation has the potential to provide improved rate support during vagally mediated syncope, as it adjusts heart rate via sensing intracardiac impedance (reflecting myocardial contractility and autonomic tone), and thus potentially provides earlier chronotropic support than standard activity or ventilation-based sensors. For our patient, we ultimately favoured cardioneural ablation due to patient factors (young age) and the potential to directly attenuate the excessive parasympathetic input mediating syncope rather than merely compensate for the downstream effect.

Figure 3. Leadless pacemaker device deployed within the right ventricle. Generated by Austin Kane utilising OpenAI, ChatGPT, October 2025.