Which medication can be used as both a local anesthetic and an antiarrhythmic for treating acute life-threatening ventricular arrhythmias?

Lidocaine is the correct answer because it possesses dual properties as both a local anesthetic and an antiarrhythmic agent. As a local anesthetic, lidocaine works by blocking sodium channels, which prevents the generation and transmission of nerve impulses, resulting in numbness in a localized area. This property makes it useful in procedures requiring localized pain management.

In the context of antiarrhythmic therapy, lidocaine is particularly effective for treating acute life-threatening ventricular arrhythmias, especially after myocardial infarction. It works by stabilizing the cardiac cell membrane and suppressing ectopic foci, which helps restore a normal rhythm in the heart. Its rapid onset and short duration of action make it a preferred choice in emergency settings for managing arrhythmias.

Other medications listed, such as propranolol, atenolol, and sotalol, are primarily beta-blockers or antiarrhythmic agents with different mechanisms, but they do not serve the role of a local anesthetic. This differentiates lidocaine as the only medication in the options given that can effectively fulfill both roles.