71 下列何種抗心律不整藥物是屬於Class IB，適用於ventricular tachyarrhythmias病人？

Propranolol Mexiletine Propafenone Amiodarone

answer mexiletine

There are five main classes in the Singh Vaughan Williams classification of antiarrhythmic agents:

• Class I agents interfere with the sodium (Na⁺) channel.
• Class II agents are anti-sympathetic nervous system agents. Most agents in this class are beta blockers.
• Class III agents affect potassium (K⁺) efflux.
• Class IV agents affect calcium channels and the AV node.
• Class V agents work by other or unknown mechanisms.

[edit]Overview table

Class	Known as	Examples	Mechanism	Clinical uses [5]
Ia	fast-channel blockers	Quinidine Procainamide Disopyramide	(Na+) channel block (intermediate association/dissociation)	Ventricular arrhythmias prevention of paroxysmal recurrent atrial fibrillation (triggered by vagaloveractivity), *procainamide in Wolff-Parkinson-White syndrome
Ib		Lidocaine Phenytoin Mexiletine	(Na+) channel block (fast association/dissociation)	treatment and prevention during and immediately after myocardial infarction, though this practice is now discouraged given the increased risk of asystole ventricular tachycardia atrial fibrillation
Ic		Flecainide Propafenone Moricizine	(Na+) channel block (slow association/dissociation)	prevents paroxysmal atrial fibrillation treats recurrent tachyarrhythmias of abnormal conduction system. contraindicated immediately post-myocardial infarction.
II	Beta-blockers	Propranolol Esmolol Timolol Metoprolol Atenolol Bisoprolol	beta blocking Propranolol also shows some class I action	decrease myocardial infarction mortality prevent recurrence of tachyarrhythmias
III		Amiodarone Sotalol Ibutilide Dofetilide E-4031	K+ channel blocker Sotalol is also a beta blocker[6]	In Wolff-Parkinson-White syndrome (sotalol:) ventricular tachycardias and atrial fibrillation (Ibutilide:) atrial flutter and atrial fibrillation
IV	slow-channel blockers	Verapamil Diltiazem	Ca2+ channel blocker	prevent recurrence of paroxysmal supraventricular tachycardia reduce ventricular rate in patients with atrial fibrillation
V		Adenosine Digoxin	Work by other or unknown mechanisms (Direct nodal inhibition).	Used in supraventricular arrhythmias, especially in Heart Failure with Atrial Fibrillation, contraindicated in ventricular arrhythmias.