Postpartum Transient Hypervagotonic Sinus Node Dysfunction Leading to Sinus Bradycardia: A Case Report

Abstract

Sinus bradycardia is common in children and adults, especially during sleep. The heart rate can drop below 30 beats per minute. Up to 35% of healthy individuals below 25 years of age, trained athletes, and those with a rare form of the familial syndrome with potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel 4 (HCN4) mutation may have asymptomatic sinus bradycardia without any heart diseases. The increased vagal tone has been associated with profound bradycardia in various pathophysiologic settings including pain. Herein, we report the first case of a young Caucasian female with transient symptomatic bradycardia due to postpartum hypervagotonic sinus node dysfunction (SND).

Cardioneuroablation for the Treatment of Hypervagotonic Sinus Node Dysfunction

“…HV-SND is a rare form of SND that manifests as symptomatic sinus bradycardia, particularly in young patients. 1 , 2 The diagnosis is based on clinical history and can be confirmed by evaluating the sinus rate response to atropine infusion. In the case of SND induced by an HV state (as opposed to SND caused by intrinsic disease of the sinus node), atropine infusion results in resolution of the bradycardia.…”

“…This type of response to atropine was consistent with hypervagotonic sinus node dysfunction (HV-SND). 1 , 2 A single-chamber atrial pacemaker was considered to treat her symptomatic HV-SND; however, given her age and history of intravenous drug misuse, this was not optimal because of increased infection risk. Cardioneuroablation (CNA) was attempted to effectively remove vagal efferent input to the sinus node.…”

Managing a Pseudo-Mobitz Type II Atrioventricular (AV) Block Intrapartum: A Case Report

“…Several causes of AV block need to be looked at in young patients such as congenital heart block, cardiomyopathy, rheumatic fever, infective endocarditis, infiltrative heart disease, drugs, or vagal tone [ 8 ]. Our patient did not have any suggestive history as such, which was excluded by blood investigation and echocardiography.…”

Advanced atrioventricular block due to hypervagotonia: Treatment with hyoscyamine

“…Hypervagotonia is an unusual cause for bradycardia that has been more commonly reported in younger patients, particularly athletes, and often in the setting of pain (4,5,6).…”

“…Hypervagotonia is an unusual cause for bradycardia that has been more commonly reported in younger patients, particularly athletes, and often in the setting of pain. 4 , 5 , 6 Sinus node dysfunction manifested by sinus bradycardia and sinus pauses are the usual arrhythmias precipitated by hypervagotonia. 4 Theophylline has been used for the treatment of hypervagotonia and in 1 study was 70% effective for eliminating symptoms associated with hypervagotonia, although permanent pacing was required in 1 patient with continued symptoms despite theophylline.…”