A rare cause of sinus node dysfunction: Neuromyelitis optica spectrum disorder with area postrema syndrome

Sinus node dysfunction (SND) or sick sinus syndrome (SSS) is a condition in which there is a disorder of the sinoatrial (SA) node resulting in impaired pacemaker function and cardiac electrical impulse transmission, leading to a variety of abnormal bradyarrhythmia and atrial arrhythmias. There are many causes of SND, of which the most common is age-related degeneration of the SA node. Other common causes include cardiac infiltrative disease, electrolyte and metabolic derangements, and drug-related causes.