Heat Stroke–Induced Sinoatrial Node Dysfunction

BackgroundHeat stroke has been associated with stress-induced cardiomyopathy and electrocardiogram ST segment elevation and depression. Laboratory studies with dogs have demonstrated heat stroke–induced sinoatrial node dysfunction in the setting of hyperkalemia. No prior case report has described heat stroke–induced complete sinoatrial node dysfunction that resolved in the emergency department.Case ReportAn 87-year-old female presented to the emergency department with heat stroke and severe bradycardia. Initial electrocardiogram demonstrated complete sinoatrial node dysfunction. The bradycardia responded to external cardiac pacing and the sinoatrial node dysfunction resolved with aggressive cooling. Emergency physicians should be aware that heat stroke can cause complete sinoatrial node dysfunction and that this bradydysthrmia can be treated with aggressive cooling.