Anti-arrhythmic drugs refer to drugs that can prevent and control tachycardia, bradycardia or arrhythmia. The second class of anti-arrhythmic drugs mainly include beta-blockers, including metoprolol tartrate, bisoprolol fumarate, atenolol, aurolol hydrochloride, esmolol hydrochloride, etc. Beta-blockers can slow down the heart rate and reduce sympathetic excitability, thus having an anti-arrhythmic effect, and are more effective for controlling sinus It is more effective in controlling sinus tachycardia, or rapid atrial fibrillation or atrial flutter. Anti-arrhythmic drugs, in addition to class II anti-arrhythmic drugs β-blockers, there are also sodium channel blockers, which are more commonly used in clinical practice, including propafenone hydrochloride, mexiletine hydrochloride, lidocaine hydrochloride, etc., which can block the sodium channels in the myocardium and cardiac conduction system to prevent tachycardia and some arrhythmias. As well as potassium channel blockers, representative drugs include amiodarone hydrochloride, sotalol hydrochloride, etc., and calcium channel blockers, common drugs include nifedipine, amlodipine besylate, felodipine, verapamil hydrochloride, etc. Class II antiarrhythmic drugs are widely used in clinical practice. In addition to antiarrhythmic effects, they also have anti-anginal and blood pressure-lowering effects, but they should be used with caution or under the guidance of a medical professional in patients with heart failure. If dizziness, headache, drowsiness, nausea, vomiting, etc. occur when applying class II antiarrhythmic drugs, they are common adverse reactions. If the symptoms are severe, go to the hospital promptly and follow the doctor’s instructions to change the drug or reduce the dosage.