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

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).