Transient Trifascicular Block in Severe Hyperkalemia.

Hyperkalemia is a commonly encountered electrolyte abnormality that can significantly alter normal cardiac conduction. Potentially lethal dysrhythmias associated with hyperkalemia include complete heart block and Mobitz Type II second-degree AV block. We report a case of trifascicular block, due to hyperkalemia. The patient's symptoms and electrocardiogram (ECG) evidence of trifascicular block resolved with lowering of serum potassium levels, with subsequent ECG showing left anterior hemiblock. This paper highlights an infrequently reported dysrhythmia associated with hyperkalemia that emergency physicians should be familiar with.