Class Ia antiarrhythmic

Definition

Class Ia antiarrhythmics are a subclass of sodium channel blockers used to treat certain types of cardiac arrhythmias. They work by slowing down the conduction of electrical impulses in the heart and elongating the action potential duration.

5 Must Know Facts For Your Next Test

1. Class Ia antiarrhythmics, such as quinidine, procainamide, and disopyramide, are used to treat atrial fibrillation and ventricular tachycardia.
2. They work by blocking sodium channels during phase 0 of the cardiac action potential, which slows conduction velocity.
3. These drugs also have a moderate effect on potassium channels, leading to an increased refractory period.
4. Common side effects include hypotension, torsades de pointes (a specific type of polymorphic ventricular tachycardia), and anticholinergic effects.
5. Monitoring is essential when administering Class Ia antiarrhythmics due to their narrow therapeutic index and risk of proarrhythmia.

Review Questions

• What are the primary mechanisms by which Class Ia antiarrhythmics affect cardiac cells?
• Name three common medications classified as Class Ia antiarrhythmics.
• What are some potential side effects associated with Class Ia antiarrhythmics?

Related terms

Class Ib antiarrhythmic: A subclass that shortens the action potential duration and is primarily used for ventricular arrhythmias.

Class Ic antiarrhythmic: A subclass that markedly slows conduction without significantly affecting the action potential duration.

Torsades de Pointes: A specific type of life-threatening polymorphic ventricular tachycardia often associated with prolonged QT interval.