Researchers presented the case report of a boy with Prader-Willi syndrome (PWS) who developed vagal asystole in Pediatrics

PWS is a hormonal disorder of the hypothalamic-pituitary-axis caused by microdeletions within chromosome 15. Despite advancements in care, patients with PWS still have greater morbidity and mortality compared with the general population. Although severe cardiological malformations are not typically associated with pediatric PWS, studies suggest that children with PWS may still be at risk of structural and/or functional cardiac alterations unrelated to obesity. 

A 10-year-old boy with PWS presented with recurrent episodes of arrhythmias and was evaluated for the possibility of pacemaker therapy. His arrhythmias were noted during an inpatient admission for pneumonia, which was confirmed with subsequent outpatient electrocardiogram (ECG) monitoring. He was found to have episodes of bradycardia (approximately 30 beats/min) and sinus arrests lasting up to 6 seconds in the absence of syncope, dizziness, or palpitations. 

Upon presentation, the boy was found to be moderately obese (body mass index, 24.2; 97th to 99th percentile). Blood investigations were normal. Structural heart disease was excluded. Inpatient monitoring over 24 hours revealed various bradycardias and asystoles of up to 6 seconds. These arrhythmias were found to be provoked via vagal stimulation by drinking large quantities of fluid. 

Read more about PWS etiology 

Subsequent ambulatory 9-day Holter ECG found multiple asystoles of 5 seconds or less with missing P-waves, followed by conversions to normal sinus rhythm. This occurred when drinking large boluses of liquid. Further investigations were carried out, with vagal-induced atrioventricular block found to be the most likely diagnosis. The patient was not fitted with a pacemaker because he was asymptomatic. 

Three months later, the patient presented with an unobserved syncope in school; 24-hour monitoring once again showed multiple asystoles, now lasting up to 7 seconds. As such, he was fitted with a ventricle-ventricle-inhibition pacemaker with a backup rate of 50 beats/min. This allowed the patient to recover quickly and he was discharged 2 days later. 

Subsequent follow-ups at 1 and 4 months postimplantation showed adequate functioning of the pacemaker. He no longer reports of any syncopal or near-syncopal events. 

“In addition to early and aggressive therapy of known cardiovascular risk factors including obesity and diabetes mellitus, we suggest that screening of children with PWS for risk of significant arrhythmias using noninvasive and cost-efficient diagnostic tools (Holter monitoring, vagal provocation and stimulation) should be evaluated,” the authors concluded. 


Thomas C, Mandilaras G, Rabenhorst D, et al. Vagal asystoles in a boy with Prader-Willi syndromePediatrics. Published online August 4, 2023. doi:10.1542/peds.2022-058216