Final answer:
Atropine is used to counteract bradycardia resulting from a severe vagal reaction to iodinated contrast material.
Step-by-step explanation:
A patient experiencing a severe vagal reaction to iodinated contrast material that includes bradycardia as a symptom may be treated initially with atropine. Atropine is an anticholinergic drug that acts as an antagonist to muscarinic acetylcholine receptors, thus blocking the effects of excess acetylcholine that can lead to a reduction in heart rate. This makes atropine the standard treatment to counteract the effects of bradycardia due to vagal reactions.