Verapamil belong to which class of antiarrythmic
**Core Concept**
Verapamil is a calcium channel blocker that affects the L-type calcium channels in the heart, leading to a reduction in the influx of calcium ions during cardiac depolarization. This results in a decrease in the contractility of the heart and a prolongation of the atrioventricular (AV) node conduction time.
**Why the Correct Answer is Right**
Verapamil belongs to the class of antiarrhythmic drugs known as Class IV antiarrhythmics. These drugs work by blocking the L-type calcium channels in the heart, which leads to a decrease in the contractility of the heart and a prolongation of the AV node conduction time. This action helps to slow the heart rate and reduce the frequency of arrhythmias. Verapamil's mechanism of action is similar to that of other Class IV antiarrhythmics, such as diltiazem and bepridil.
**Why Each Wrong Option is Incorrect**
**Option A:** Verapamil is not a Class I antiarrhythmic, as it does not work by blocking sodium channels in the heart.
**Option B:** Verapamil is not a Class II antiarrhythmic, as it does not work by increasing the expression of beta-adrenergic receptors in the heart.
**Option C:** Verapamil is not a Class III antiarrhythmic, as it does not work by prolonging the action potential duration in the heart.
**Clinical Pearl / High-Yield Fact**
Verapamil can cause significant hypotension and bradycardia due to its effects on the AV node and calcium channels, so it should be used with caution in patients with heart failure or other cardiovascular diseases.
**Correct Answer:** C. Class IV antiarrhythmic.