Some anesthetic agents administered during general anesthesia can cause heart rhythm disorders, mainly associated with autonomic imbalance. Off-target cardiac sodium channel blockade is considered the canonical mechanism behind cardiotoxicity.

Lidocaine, the most common local anesthetic, produces a transient loss of sensory, motor, and autonomic function when the drug is injected or applied close to neural tissues; furthermore, it has a good safety margin before reaching toxic blood levels. However, care must be taken to keep track of the total dose given to minimize its systemic toxicity. In addition to direct nerve toxicity, systemic toxicity affecting the brain and/or cardiac muscle can also occur. Cardiovascular toxicity usually appears as tachycardia and hypertension; however, with increasing toxicity, bradycardia and hypotension can occur. Ventricular arrhythmias and cardiac arrest also have been described. Because of its potential effects upon the heart, it is also commonly used as an antiarrhythmic agent to depress ventricular arrhythmias in controlled doses.

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