Atropine-resistant bradycardia due to hyperkalaemia.

Symptomatic sinus bradycardia is routinely treated in the emergency department with atropine and pacing. Two cases are presented that illustrate the importance of considering hyperkalaemia, particularly in the presence of atropine-resistant symptomatic bradycardia. The administration of calcium in such cases acts to stabilise the myocardium and resolve the bradycardia. Blood gas analysis provides a rapid estimate of serum potassium concentrations, facilitating timely treatment.