Antidysrhythmic drugs

Definition

Antidysrhythmic drugs are medications used to treat abnormal heart rhythms. They work by modifying the electrical impulses within the heart to maintain a normal rhythm.

5 Must Know Facts For Your Next Test

1. Class I antidysrhythmic drugs are sodium channel blockers.
2. Sodium channel blockers are further subdivided into Class IA, IB, and IC based on their effects on the cardiac action potential.
3. Class IA drugs (e.g., quinidine, procainamide) prolong the action potential duration and refractory period.
4. Class IB drugs (e.g., lidocaine, phenytoin) shorten the action potential duration and are particularly effective in treating ventricular arrhythmias.
5. Class IC drugs (e.g., flecainide, propafenone) have minimal effect on the action potential duration but significantly slow conduction.

Review Questions

• What distinguishes Class IA, IB, and IC antiarrhythmic drugs?
• Which class of sodium channel blockers is most effective for treating ventricular arrhythmias?
• How do Class IA antidysrhythmic drugs affect the cardiac action potential?

Related terms

Arrhythmia: An irregular or abnormal heart rhythm.

Action Potential: The change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell.

Refractory Period: The period during which a nerve or muscle is unresponsive to further stimulation.