Antiarrhythmic drug

Antiarrhythmic drugs are a group of pharmaceuticals that are used to suppress abnormal rhythms of the heart, such as atrial fibrillation, atrial flutter, ventricular tachycardia, and ventricular fibrillation.

Classification

Antiarrhythmic drugs are classified into four main classes (I, II, III, IV) based on the Vaughan Williams classification system. This system was designed by Miles Vaughan Williams in 1970.

Class I

Class I antiarrhythmic drugs interfere with the sodium (Na+) channel. They are subdivided into three categories: Ia, Ib, and Ic, which have different effects on the action potential.

Class II

Class II antiarrhythmic drugs are anti-sympathetic nervous system agents. Most agents in this class are beta blockers.

Class III

Class III antiarrhythmic drugs affect potassium (K+) efflux. They prolong repolarization and increase the duration of action potentials.

Class IV

Class IV antiarrhythmic drugs affect calcium channels and the AV node. Most agents in this class are calcium channel blockers.

Mechanism of action

Antiarrhythmic drugs work by altering the conduction of electrical impulses in the heart. They achieve this by blocking ion channels, inhibiting sympathetic stimulation of the heart, and prolonging repolarization.

Side effects

Like all drugs, antiarrhythmic drugs can have side effects. These can include dizziness, nausea, shortness of breath, and heart failure. It is important for patients to discuss these potential side effects with their healthcare provider before starting treatment.

See also

• Cardiac arrhythmia
• Cardiovascular disease
• Pharmacology