Atrioventricular block: an unusual complication of Graves' disease.

We report the case of a 10-year-old girl treated with atenolol and carbimazole for tachycardia and hypertension associated with Graves' disease who developed symptomatic 2:1 heart block. 2:1 heart block resolved following cessation of atenolol, reduction in carbimazole dose and treatment of suspected tonsillitis. First-degree atrioventricular block persisted, but gradually normalised following improvement in thyroid status.