Okay, let's tackle this question. The question is asking which local anesthetic is also used as an antiarrhythmic agent. Hmm. I remember that local anesthetics work by blocking sodium channels, which is why they numb areas. But some of them have other uses in cardiology.

Wait, the options aren't given, but the correct answer is supposed to be one of them. Let me think. Common local anesthetics include lidocaine, bupivacaine, procaine, and maybe tetracaine. Now, which of these are used as antiarrhythmics? Lidocaine is a classic one. I think it's a class 1b antiarrhythmic. It's used in treating ventricular arrhythmias, right? Like after a myocardial infarction.

So the core concept here is the dual use of local anesthetics as antiarrhythmics. The mechanism would involve sodium channel blockade, stabilizing the cardiac cell membrane. Now, why would other options be wrong? Bupivacaine is a local anesthetic, but I don't think it's used for arrhythmias. Procaine is another local anesthetic, but it's not used in cardiac arrhythmias. Tetracaine is a long-acting local anesthetic, again not used for arrhythmias.

The clinical pearl here is to remember that lidocaine is the local anesthetic with antiarrhythmic properties. The exam might try to trick you with other local anesthetics that aren't used for this purpose. Also, know the classification of antiarrhythmics—lidocaine is class 1b, which is sodium channel blockers with intermediate duration.

Putting this all together, the correct answer should be lidocaine. The options would be other local anesthetics that don't have this use. So if the options included lidocaine, that's the right one. The explanation should highlight the sodium channel blockade and the specific use in arrhythmias. The other options are incorrect because they don't have established antiarrhythmic use. The clinical pearl reinforces the key point that lidocaine is the local anesthetic used in this context.

**Core Concept**
Local anesthetics block voltage-gated sodium channels (Naᵥ1.5 in cardiac tissue), reducing action potential duration. Lidocaine, a class 1b antiarrhythmic, exploits this mechanism to stabilize cardiac membranes and suppress ventricular arrhythmias.

**Why the Correct Answer is Right**
Lidocaine inhibits cardiac sodium channels, slowing phase 0 depolarization in Purkinje fibers and ventricular myocytes. It preferentially acts on ischemic or injured tissue, reducing automaticity and conduction velocity. This makes it ideal for acute arrhythmias like ventricular tachycardia or post-MI management.

**Why Each Wrong Option is Incorrect**
**Option A:** Bupivacaine is a local anesthetic with prolonged cardiac toxicity at high doses, but it’s not used as an antiarrhythmic. **Option B:** Procaine lacks cardiostable properties and is not indicated for arrhythmias. **Option C:** Tetracaine is a long-acting local anesthetic with no role in antiarrhythmic therapy.

**Clinical Pearl / High-Yield Fact**
Lidocaine is

✓ Correct Answer: B. Lignocaine