Group IV antiarrhythmics

What are Group IV antiarrhythmics?

Group IV antiarrhythmics: Calcium-channel blockers, which inhibit the calcium channels reducing the movement of calcium ions in the cells during action potentials.

Class IV agents are slow non-dihydropyridine calcium channel blockers. They decrease conduction through the AV node, and shorten phase two (the plateau) of the cardiac action potential. They thus reduce the contractility of the heart, so may be inappropriate in heart failure.

Amiodarone is the most common antiarrhythmic medication used to suppress ventricular arrhythmia. In patients with hemodynamically unstable persistent VA after defibrillation, intravenous amiodarone should be administered to achieve a stable rhythm.

Class IV antidysrhythmic medications, also known as calcium channel blockers, are a class of medications that help control dysrhythmias. Verapamil and diltiazem are the two calcium channel blockers used to treat dysrhythmias and are classified as nondihydropyridines.

Class IV antidysrhythmic drugs inhibit the slow calcium channel inward current. They decrease the slop of phases 0 and 4 and prolong phase 2 of the cardiac action potential. They reduce the conduction velocity and increase the effective refractory period (resting state in a depolarized cardiac cell) and prolong atrioventricular node repolarization and P-R interval.