Pacemaker ECG with the Littmann sign.

Severe hyperkalemia may be concealed in the electrocardiogram (ECG). We present the case of a critically ill patient with severe bradycardia and the BRASH syndrome. In critically ill patients, double counting of the heart rate is frequently a marker of severe hyperkalemia (Littmann sign). In our case, hyperkalemic double counting only appeared in the ECG performed during percutaneous pacing. The Littmann sign helped with the early recognition of hyperkalemia and the BRASH syndrome.