The vagus reaction as a possible cause of severe complications of radiological procedures.

Six severe reactions which appeared to be mediated via the vagus nerve were encountered in the course of various radiological procedures. Four patients were treated with intravenous atropine and responded successfully. The vagus reaction is proposed as a possible mechanism of death in the "allergic" reaction to contrast media seen during radiological procedures. This phenomenon and its treatment and prevention are discussed, as is its difference from the histamine effect.