Second-degree heart block associated with envenomation by Vipera berus.

Evenomation by the common European adder (Vipera berus) is well known for its significant morbidity but low mortality. Cardiac complications tend to take second place to the systemic upset and usually only comprise non-specific ECG changes. This case illustrates many of the classical features of adder bite but it is also the first account of heart block as a complication.