LAUSR

Introduction Atrial standstill (AS), a rare arrhythmogenic condition, is defined by (1) the absence of P waves in surface and intracavitary electrocardiograms (ECGs), (2) the absence of A waves in jugular venous pulse and right atrial pressure tracings, (3) the presence of a supraventricular type QRS complex, (4) the immobility of the atria on fluoroscopy, and (5) the inability to stimulate the atria electrically. Several etiologies have been identified including metabolic derangements, ischemia, drug intoxication, amyloidosis, and muscular dystrophies. The discovery of familial AS leads to the identification of channelopathies involved, particularly SCN5A mutations leading to Nav1.5 sodium channel dysfunction. AS is rarely reported in pediatric patients. An 11-year-old with permanent AS was found to have an SCN5A mutation; a 3-year-old developed AS transiently after dexmedetomidine infusion; and systemic illness was implicated in an 8-year-old with thiamine-responsive megaloblastic anemia. Here we present a unique case of AS, possibly due to novel caveolin-3 (CAV3) mutation, in a pediatric patient whose clinical presentation and progression were unusual.